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  • 1. Aguilar, Luis T.
    et al.
    Boiko, Igor M.
    Fridman, Leonid M.
    Freidovich, Leonid B.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Generating oscillations in inertia wheel pendulum via two-relay controller2012Ingår i: International Journal of Robust and Nonlinear Control, ISSN 1049-8923, E-ISSN 1099-1239, Vol. 22, nr 3, s. 318-330Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The problem of generating oscillations of the inertia wheel pendulum is considered. We combine exact feedback linearization with two-relay controller, tuned using frequency-domain tools, such as computing the locus of a perturbed relay system. Explicit expressions for the parameters of the controller in terms of the desired frequency and amplitude are derived. Sufficient conditions for orbital asymptotic stability of the closed-loop system are obtained with the help of the Poincare map. Performance is validated via experiments. The approach can be easily applied for a minimum phase system, provided the behavior of the states of the zero dynamics is of no concern. Copyright (C) 2011 John Wiley & Sons, Ltd.

  • 2.
    Aguilar, Luis T.
    et al.
    CITEDI, National Polytechnic Institute, Tijuana, BC, Mexico.
    Freidovich, Leonid
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Orlov, Yury
    CICESE Research Center, Ensenada, Baja California, Mexico.
    Merida, Jovan
    CITEDI, National Polytechnic Institute, Tijuana, BC, Mexico.
    Performance Analysis of Relay Feedback Position Regulators for Manipulators with Coulomb Friction2013Ingår i: Proc. 12th European Control Conference, NEW YORK, NY 10017 USA: IEEE , 2013, s. 3754-3759Konferensbidrag (Refereegranskat)
    Abstract [en]

    The purpose of the paper is to analyze the performance of several global position regulators for robot manipulators with Coulomb friction. All the controllers include a proportional-differential part and a switched part whereas the difference between the controllers is in the way of compensation of the gravitational forces. Stability analysis is also revisited within the nonsmooth Lyapunov function framework for the controllers with and without gravity pre-compensation. Performance issues of the proposed controllers are evaluated in an experimental study of a five degrees-of-freedom robot manipulator. In the experiments, we choose two criteria for performance analysis. In the first set of experiments, we set the same gains to all the controllers. In the second set of experiments, the gains of the controller were chosen such that the work done by the manipulator is similar.

  • 3.
    Asaro, Peter M.
    Umeå universitet, Humanistiska fakulteten, Humlab.
    A Body to Kick, but Still No Soul to Damn: Legal Perspectives on Robotics2012Ingår i: Robot Ethics: The Ethical and Social Implications of Robotics / [ed] Patrick Lin, Keith Abney and George A. Bekey, CAMBRIDGE: MIT Press, 2012, s. 169-186Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 4.
    Augustian, Midhumol
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    ur Réhman, Shafiq
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Sandvig, Axel
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap. Norwegian University of Science and Technology (NTNU), Norway.
    Kotikawatte, Thivra
    Umeå universitet, Medicinska fakulteten, Institutionen för farmakologi och klinisk neurovetenskap.
    Yongcui, Mi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Evensmoen, Hallvard Røe
    Norwegian University of Science and Technology (NTNU), Norway.
    EEG Analysis from Motor Imagery to Control a Forestry Crane2018Ingår i: Intelligent Human Systems Integration (IHSI 2018) / [ed] Karwowski, Waldemar, Ahram, Tareq, 2018, Vol. 722, s. 281-286Konferensbidrag (Refereegranskat)
    Abstract [en]

    Brain-computer interface (BCI) systems can provide people with ability to communicate and control real world systems using neural activities. Therefore, it makes sense to develop an assistive framework for command and control of a future robotic system which can assist the human robot collaboration. In this paper, we have employed electroencephalographic (EEG) signals recorded by electrodes placed over the scalp. The human-hand movement based motor imagery mentalization is used to collect brain signals over the motor cortex area. The collected µ-wave (8–13 Hz) EEG signals were analyzed with event-related desynchronization/synchronization (ERD/ERS) quantification to extract a threshold between hand grip and release movement and this information can be used to control forestry crane grasping and release functionality. The experiment was performed with four healthy persons to demonstrate the proof-of concept BCI system. From this study, it is demonstrated that the proposed method has potential to assist the manual operation of crane operators performing advanced task with heavy cognitive work load.

  • 5.
    Bagheri, Shahriar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Modeling, Simulation and Control System Design for Civil Unmanned Aerial Vehicle (UAV)2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Unmanned aerial systems have been widely used for variety of civilian applications over the past few years. Some of these applications require accurate guidance and control. Consequently, Unmanned Aerial Vehicle (UAV) guidance and control attracted many researchers in both control theory and aerospace engineering. Flying wings, as a particular type of UAV, are considered to have one of the most efficient aerodynamic structures. It is however difficult to design robust controller for such systems. This is due to the fact that flying wings are highly sensitive to control inputs.

    The focus of this thesis is on modeling and control design for a UAV system. The platform understudy is a flying wing developed by SmartPlanes Co. located in Skellefteå, Sweden. This UAV is particularly used for topological mapping and aerial photography.

    The novel approach suggested in this thesis is to use two controllers in sequence. More precisely, Linear Quadratic Regulator (LQR) is suggested to provide robust stability, and Proportional, Integral, Derivative (PID) controller is suggested to provide reference signal regulation. The idea behind this approach is that with LQR in the loop, the system becomes more stable and less sensitive to control signals. Thus, PID controller has an easier task to do, and is only used to provide the required transient response.

    The closed-loop system containing the developed controller and a UAV non-linear dynamic model was simulated in Simulink. Simulated controller was then tested for stability and robustness with respect to some parametric uncertainty. Obtained results revealed that the LQR successfully managed to provide robust stability, and PID provided reference signal regulation.

  • 6.
    Baranwal, Neha
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Singh, Avinash
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Bensch, Suna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Extracting Primary Objects and Spatial Relations from Sentences2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    In verbal human-robot interaction natural language utterances have to be grounded in visual scenes by the robot. Visual language grounding is a challenging task that includes identifying a primary object among several objects, together with the object properties and spatial relations among the objects. In this paper we focus on extracting this information from sentences only. We propose two language modelling techniques, one uses regular expressions and the other one utilizes Euclidian distance. We compare these two proposed techniques with two other techniques that utilize tree structures, namely an extended Hobb’s algorithm and an algorithm that utilizes a Stanford parse tree. A comparative analysis between all language modelling techniques shows that our proposed two approaches require less computational time than the tree-based approaches. All approaches perform good identifying the primary object and its property, but for spatial relation extraction the Stanford parse tree algorithm performs better than the other language modelling techniques. Time elapsed for the Stanford parse tree algorithm is higher than for the other techniques.

  • 7.
    Barth, Ruud
    et al.
    Greenhouse Horticulture, Wageningen University & Research Center.
    Baur, Jörg
    Institute of Applied Mechanics, Technische Universität München.
    Buschmann, Thomas
    Institute of Applied Mechanics, Technische Universität München.
    Edan, Yael
    Department of Industrial Engineering and Management, Ben-Gurion University of the Negev.
    Hellström, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Nguyen, Thanh
    KU Leuven, Department of Biosystems.
    Ringdahl, Ola
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Saeys, Wouter
    KU Leuven, Department of Biosystems.
    Salinas, Carlota
    Centre for Automation and Robotics UPM-CSIC.
    Vitzrabin, Efi
    Department of Industrial Engineering and Management, Ben-Gurion University of the Negev.
    Using ROS for agricultural robotics: design considerations and experiences2014Ingår i: RHEA-2014 / [ed] Pablo Gonzalez-de-Santos and Angela Ribeiro, 2014, s. 509-518Konferensbidrag (Refereegranskat)
    Abstract [en]

    We report on experiences of using the ROS middleware for developmentof agricultural robots. We describe software related design considerations for all maincomponents in developed subsystems as well as drawbacks and advantages with thechosen approaches. This work was partly funded by the European Commission(CROPS GA no 246252).

  • 8.
    Bensch, Suna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap. Department of Computing Science.
    Jevtic, Aleksandar
    Institut de Robotica i Informatica Industrial, Technical University of Catalonia, Spain.
    Hellström, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    On Interaction Quality in Human-Robot Interaction2017Ingår i: Proceedings of the 9th International Conference on Agents and Artificial Intelligence / [ed] H. Jaap van den Herik, Ana Paula Rocha, Joaquim Filipe, Setúbal: SciTePress, 2017, Vol. 1, s. 182-189Konferensbidrag (Refereegranskat)
    Abstract [en]

    In many complex robotics systems, interaction takes place in all directions between human, robot, and environment. Performance of such a system depends on this interaction, and a proper evaluation of a system must build on a proper modeling of interaction, a relevant set of performance metrics, and a methodology to combine metrics into a single performance value. In this paper, existing models of human-robot interaction are adapted to fit complex scenarios with one or several humans and robots. The interaction and the evaluation process is formalized, and a general method to fuse performance values over time and for several performance metrics is presented. The resulting value, denoted interaction quality, adds a dimension to ordinary performance metrics by being explicit about the interplay between performance metrics, and thereby provides a formal framework to understand, model, and address complex aspects of evaluation of human-robot interaction. 

  • 9.
    Billing, Erik
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Hellström, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Janlert, Lars Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Simultaneous control and recognition of demonstrated behavior2011Rapport (Övrigt vetenskapligt)
    Abstract [en]

    A method for Learning from Demonstration (LFD) is presented and evaluated on a simulated Robosoft Kompai robot. The presented algorithm, called Predictive Sequence Learning (PSL), builds fuzzy rules describing temporal relations between sensory-motor events recorded while a human operator is tele-operating the robot. The generated rule base can be used to control the robot and to predict expected sensor events in response to executed actions. The rule base can be trained under different contexts, represented as fuzzy sets. In the present work, contexts are used to represent different behaviors. Several behaviors can in this way be stored in the same rule base and partly share information. The context that best matches present circumstances can be identified using the predictive model and the robot can in this way automatically identify the most suitable behavior for precent circumstances. The performance of PSL as a method for LFD is evaluated with, and without, contextual information. The results indicate that PSL without contexts can learn and reproduce simple behaviors. The system also successfully identifies the most suitable context in almost all test cases. The robot's ability to reproduce more complex behaviors, with partly overlapping and conflicting information, significantly increases with the use of contexts. The results support a further development of PSL as a component of a dynamic hierarchical system performing control and predictions on several levels of abstraction. 

  • 10. Bontsema, J.
    et al.
    Hemming, J.
    Pekkeriet, E.
    Saeys, W.
    Edan, Y.
    Shapiro, A.
    Hočevar, M.
    Hellström, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Oberti, R.
    Armada, M.
    Ulbrich, H.
    Baur, J.
    Debilde, B.
    Best, S.
    Evain, S.
    Gauchel, W.
    Ringdahl, Ola
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    CROPS: high tech agricultural robots2014Konferensbidrag (Övrigt vetenskapligt)
  • 11. Eriksson, Lennart
    et al.
    Trygg, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wold, Svante
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Umetrics Inc., 42 Pine Hill Rd, Hollis, NH 03049, USA.
    PLS-trees (R), a top-down clustering approach2009Ingår i: Journal of Chemometrics, ISSN 0886-9383, E-ISSN 1099-128X, Vol. 23, nr 11, s. 569-580Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A hierarchical clustering approach based on a set of PLS models is presented. Called PLS-Trees (R), this approach is analogous to classification and regression trees (CART), but uses the scores of PLS regression models as the basis for splitting the clusters, instead of the individual X-variables. The split of one cluster into two is made along the sorted first X-score (t(1)) of a PLS model of the cluster, but may potentially be made along a direction corresponding to a combination of scores. The position of the split is selected according to the improvement of a weighted combination of (a) the variance of the X-score, (b) the variance of Y and (c) a penalty function discouraging an unbalanced split with very different numbers of observations. Cross-validation is used to terminate the branches of the tree, and to determine the number of components of each cluster PLS model. Some obvious extensions of the approach to OPLS-Trees and trees based on hierarchical PLS or OPLS models with the variables divided in blocks depending on their type, are also mentioned. The possibility to greatly reduce the number of variables in each PLS model on the basis of their PLS w-coefficients is also pointed out. The approach is illustrated by means of three examples. The first two examples are quantitative structure-activity relationship (QSAR) data sets, while the third is based on hyperspectral images of liver tissue for identifying different sources of variability in the liver samples.

  • 12.
    Fodor, Szabolcs
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Towards semi-automation of forestry cranes: automated trajectory planning and active vibration damping2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Forests represent one of the biggest terrestrial ecosystems of Earth, that can produce important raw renewable materials such as wood with the help of sun, air and water. To efficiently extract these raw materials, the tree harvesting process is highly mechanized in developed countries, meaning that advanced forestry machines are continuously used to fell, to process and to transport the logs and biomass obtained from the forests. However, working with these machines is demanding both mentally and physically, which are known factors to negatively affect operator productivity. Mental fatigue is mostly due to the manual operation of the on-board knuckleboom crane, which requires advanced cognitive work with two joystick levers, while the most serious physical strains arise from cabin vibrations. These vibrations are generated from knuckleboom crane vibrations as a result of aggressive manual operation.

    To enhance operator workload, well-being, and to increase productivity of the logging process, semi-automation functions are suggested, which are supervised automatic executions of specific work elements. Some of the related issues are addressed in the current thesis. Therefore, the content is divided into: (1) the design and development of a semi-automation function focused only on the base joint actuator (slewing actuator) of a knuckleboom crane, and (2) active vibration damping solutions to treat crane structure vibrations induced by the main lift cylinder (inner boom actuator). The considered reference machine is a downsized knuckleboom crane of a forwarder machine, which is used to pick up log assortments from a harvesting site.

    The proposed semi-automation function presented in the first part could be beneficial for operators to use during log loading/unloading scenarios. It consists from a closed-loop position control architecture, to which smooth reference slewing trajectories are provided by a trajectory planner that is automated via operator commands. The used trajectory generation algorithms are taken from conventional robotics and adapted to semi-automation context with proposed modifications that can be customizable by operators.

    Further, the proposed active vibration damping solutions are aimed to reduce vibrations of the knuckleboom crane excited by the inner boom actuator due to aggressive manual commands. First, a popular input shaping control technique combined with a practical switching logic was investigated to deal with the excited payload oscillations. This technique proved to be useful with a fixed crane pose, however it did not provide much robustness in terms of different link configurations. To tackle this problem an H2-optimal controller is developed, which is active in the pressure feedback-loop and its solely purpose is to damp the same payload oscillations. During the design process, operator commands are treated and explained from input disturbance viewpoint.

    All of the hypothesis throughout this thesis were verified with extensive experimental studies using the reference machine.

  • 13.
    Fodor, Szabolcs
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Freidovich, Leonid
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Active vibration damping using H2-optimal feedback control design for forestry cranesManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Nowadays, forest harvesting is highly mechanized. The commercially available forestry machines are equipped with knuckleboom cranes that are hydraulically actuated, and manually controlled through a set of joysticks and buttons. A common problem that human operators face during manipulation of such knuckleboom cranes, are the crane structure oscillations created by non-smooth or too aggressive manual joystick-based commands. These oscillations not only contribute to actuator wear, but are also dangerous for operators and the environment as well. The current paper investigates the oscillation attenuation induced by the motion of the inner boom actuator and is based on H2-optimal controller synthesis active in the pressure feedback loop. Furthermore, the controller robustness is verified experimentally considering different working conditions of the reference machine, which also verifies the effectiveness of the approach. 

  • 14.
    Fodor, Szabolcs
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Freidovich, Leonid
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Vázquez, Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Practical trajectory designs for semi-automation of forestry cranes2016Ingår i: Proceedings of  ISR 2016: 47th International Symposium on Robotics, VDE Verlag GmbH, 2016, s. 1-8Konferensbidrag (Refereegranskat)
    Abstract [en]

    Simplifying the operation of forestry machines with operator-centered semi-automation is needed in the modern timber harvesting industry in order to increase operator productivity and comfort, to reduce learning time of novice operators and to ensure safer manipulation of the cranes. In this paper, useful tools towards operator-centered semi-automation of the base joint actuator of a forwarder crane are proposed. The main goal is to allow comfortable automated motions that do not excite dangerous oscillations of the freely-hanging grapple. Moreover, operator commands are used interactively with a closed-loop position control scheme to assure automated slewing motions. Smooth reference trajectories are provided for the position controller with an on-line trajectory generation algorithm that is developed by combining properties of two standard trajectory generation methods. A practical algorithm based on experiments is introduced to find the trajectory that guaranties minimal grapple oscillations within a set of relatively fast trajectories. Further on, the log loading/unloading tasks are discussed and verified experimentally using the proposed approach on a forwarder crane prototype.

  • 15.
    Fodor, Szabolcs
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Vázquez, Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Freidovich, Leonid
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Automation of slewing motions for forestry cranes2015Ingår i: 2015 15th International Conference on Control, Automation and Systems (ICCAS), IEEE, 2015, s. 796-801Konferensbidrag (Refereegranskat)
    Abstract [en]

    The modern timber harvesting industry would be ineffective without heavy duty advanced machinery used for logging. However, with benefits of mechanization comes the operation complexity. Introducing automation is expected to reduce the mental and physical load on the operator and improve the machine use efficiency. Nonetheless, with current technology fully autonomous timber harvesting is impossible. In this paper a semi-automation scenario is presented using the base joint actuator of a forestry forwarder crane taking into consideration the need to attenuate unwanted oscillations of its hanging grapple. We address the necessary motion planning and motion stabilization tasks. To reduce oscillations along a nominal trajectory, we design smooth reference profiles based on experiments. Meanwhile, a practical structure for a feedback controller is proposed and tested. In this process, actuator nonlinearities are dealt with feasible identification and compensation techniques.

  • 16.
    Fodor, Szabolcs
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Vázquez, Carlos
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Freidovich, Leonid
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Interactive on-line trajectories for semi-automation: case study of a forwarder crane2016Ingår i: Proceedings of 2016 IEEE International Conference on Automation Science and Engineering (CASE), IEEE, 2016, s. 928-933Konferensbidrag (Refereegranskat)
    Abstract [en]

    Working with forestry cranes is not easy due to their complex mechanical structure, non-linear behavior of the hydraulic actuation system, and non-intuitive joint-based control; however, with automation, the level of manipulation difficulty can be reduced. This is potentially useful for the operators since they are prone to be more productive if semi-automation functions are introduced to a certain level. In this paper, a semi-automation function for the base joint actuator of a forestry forwarder crane is proposed. The semi-automation function is based on a design of an interactive on-line trajectory generation algorithm with variable final time that acts as a reference signal to a closed-loop position controller. Moreover, the advantage of this scheme is that the operators are kept in the loop by directly being in charge of controlling the final time for the on-line trajectory generation algorithm. Experiments with a downsized industry-standard forwarder crane verify the applicability and advantage of the proposed scheme.

  • 17.
    Fodor, Szabolcs
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Vázquez, Carlos
    Ålö AB, Umeå, Sweden.
    Freidovich, Leonid
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Sepehri, Nariman
    Towards oscillation reduction in forestry cranes2016Ingår i: Proceedings of the Bath/ASME 2016 Symposium on Fluid Power and Motion Control, ASME Press, 2016, artikel-id V001T01A049Konferensbidrag (Refereegranskat)
    Abstract [en]

    Smooth operation of heavy-duty forestry cranes is not an easy task for the operators with the current joystick-based control method that is complex and non-intuitive. Moreover, abrupt movements of the same joysticks provoke aggressive signals that can lead to oscillatory motions in the actuators and in the entire crane. These oscillations, not only contribute to wear of the joint actuators but also can cause damage to both the operators and the environment; therefore, they must be attenuated. The proposed approach in this paper uses the popular input shaping control technique combined with a practical switching logic to deal with different frequency payload oscillations induced by the motion of the inner boom actuator of a forwarder crane. The results show a significant improvement in terms of visible oscillation reduction monitored through their appearance in the torque signal computed from pressure measurements. Experiments performed on a down-sized forestry crane verifies the effectiveness of the approach.

  • 18.
    Fonooni, Benjamin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Cognitive Interactive Robot Learning2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Att bygga autonoma robotar som passar ett stort antal olika användardefinierade applikationer kräver ett språng från dagens specialiserade maskiner till mer flexibla lösningar. För att nå detta mål, bör man övergå från traditionella förprogrammerade robotar till robotar som själva kan lära sig nya färdigheter. Learning from Demonstration (LfD) och Imitation Learning (IL), där roboten lär sig genom att observera en människa eller en annan robot, är bland de mest populära inlärningsteknikerna. Att visa roboten hur den ska utföra en uppgift är ofta mer naturligt och intuitivt än att modifiera ett komplicerat styrprogram. Men att lära robotar nya färdigheter så att de kan reproducera dem under nya yttre förhållanden, på rätt tid och på ett lämpligt sätt, kräver god förståelse för alla utmaningar inom området. Studier av LfD och IL hos människor och djur visar att flera kognitiva förmågor är inblandade för att lära sig nya färdigheter på rätt sätt. De mest anmärkningsvärda är förmågan att rikta uppmärksamheten på de relevanta aspekterna i en demonstration, och förmågan att anpassa observerade rörelser till robotens egen kropp. Dessutom är det viktigt att ha en klar förståelse av lärarens avsikter, och att ha förmågan att kunna generalisera dem till nya situationer. När en inlärningsfas är slutförd kan stimuli trigga det kognitiva systemet att utföra de nya färdigheter som blivit en del av robotens repertoar. Målet med denna avhandling är att utveckla metoder för LfD som huvudsakligen fokuserar på att förstå lärarens intentioner, och vilka delar av en demonstration som ska ha robotens uppmärksamhet. Den föreslagna arkitekturen innehåller de kognitiva funktioner som behövs för lärande och återgivning av högnivåaspekter av demonstrationer. Flera inlärningsmetoder för att rikta robotens uppmärksamhet och identifiera relevant information föreslås. Arkitekturen integrerar motorkommandon med begrepp, föremål och omgivningens tillstånd för att säkerställa korrekt återgivning av beteenden. Ett annat huvudresultat i denna avhandling rör metoder för att lösa tvetydigheter i demonstrationer, där lärarens intentioner inte är klart uttryckta och flera demonstrationer är nödvändiga för att kunna förutsäga intentioner på ett korrekt sätt. De utvecklade lösningarna är inspirerade av modeller av människors minne, och en primingmekanism används för att ge roboten ledtrådar som kan öka sannolikheten för att intentioner förutsägs på ett korrekt sätt. De utvecklade teknikerna har, i tillägg till robotinlärning, använts i ett halvautomatiskt system (shared control) baserat på visuellt guidade beteenden och primingmekanismer. Arkitekturen och inlärningsteknikerna tillämpas och utvärderas i flera verkliga scenarion som kräver en tydlig förståelse av mänskliga intentioner i demonstrationerna. Slutligen jämförs de utvecklade inlärningsmetoderna, och deras applicerbarhet under olika förhållanden diskuteras.

  • 19.
    Fonooni, Benjamin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Robot Learning and Reproduction of High-Level Behaviors2013Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Learning techniques are drawing extensive attention in the robotics community. Some reasons behind moving from traditional preprogrammed robots to more advanced human fashioned techniques are to save time and energy, and allow non-technical users to easily work with robots. Learning from Demonstration (LfD) and Imitation Learning (IL) are among the most popular learning techniques to teach robots new skills by observing a human or robot tutor.

    Flawlessly teaching robots new skills by LfD requires good understanding of all challenges in the field. Studies of imitation learning in humans and animals show that several cognitive abilities are engaged to correctly learn new skills. The most remarkable ones are the ability to direct attention to important aspects of demonstrations, and adapting observed actions to the agents own body. Moreover, a clear understanding of the demonstrator's intentions is essential for correctly and completely replicating the behavior with the same effects on the world. Once learning is accomplished, various stimuli may trigger the cognitive system to execute new skills that have become part of the repertoire.

    Considering identified main challenges, the current thesis attempts to model imitation learning in robots, mainly focusing on understanding the tutor's intentions and recognizing what elements of the demonstration need the robot's attention. Thereby, an architecture containing required cognitive functions for learning and reproducing high-level aspects of demonstrations is proposed. Several learning methods for directing the robot's attention and identifying relevant information are introduced. The architecture integrates motor actions with concepts, objects and environmental states to ensure correct reproduction of skills. This is further applied in learning object affordances, behavior arbitration and goal emulation.

    The architecture and learning methods are applied and evaluated in several real world scenarios that require clear understanding of goals and what to look for in the demonstrations. Finally, the developed learning methods are compared, and conditions where each of them has better applicability is specified.

  • 20.
    Fonooni, Benjamin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Sequential Learning From Demonstration Based On Semantic Networks2012Ingår i: Proceedings of Umeå's 15th Student Conference in Computing Science (USCCS 2012) / [ed] Suna Bensch, Frank Drewes, Håkan Gulliksson and Thomas Mejtoft, Umeå: Umeå University , 2012, s. 39-47Konferensbidrag (Refereegranskat)
    Abstract [en]

    Most of the humans day to day tasks include sequences ofactions that lead to a desired goal. In domains which humans are replacedby robots, the ability of learning new skills easy and fast plays animportant role. The aim of this research paper is to incorporate sequentiallearning into Learning from Demonstration (LfD) in an architecturewhich mainly focuses on high-level representation of behaviors. The primarygoal of the research is to investigate the possibility of utilizingSemantic Networks in order to enable the robot to learn new skills insequences.

  • 21.
    Fonooni, Benjamin
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Hellström, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Janlert, Lars-Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Learning High-Level Behaviors From Demonstration Through Semantic Networks2012Ingår i: Proceedings of 4th International Conference on Agents and Artificial Intelligence, 2012, s. 419-426Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we present an approach for high-level behavior recognition and selection integrated with alow-level controller to help the robot to learn new skills from demonstrations. By means of SemanticNetwork as the core of the method, the robot gains the ability to model the world with concepts and relatethem to low-level sensory-motor states. We also show how the generalization ability of Semantic Networkscan be used to extend learned skills to new situations.

  • 22.
    Fonooni, Benjamin
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Hellström, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Janlert, Lars-Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Towards Goal Based Architecture Design for Learning High-Level Representation of Behaviors from Demonstration2013Ingår i: 2013 IEEE International Multi-Disciplinary Conference on Cognitive Methods in Situation Awareness and Decision Support (CogSIMA), 2013, s. 67-74Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper gives a brief overview of challenges indesigning cognitive architectures for Learning fromDemonstration. By investigating features and functionality ofsome related architectures, we propose a modular architectureparticularly suited for sequential learning high-levelrepresentations of behaviors. We head towards designing andimplementing goal based imitation learning that not only allowsthe robot to learn necessary conditions for executing particularbehaviors, but also to understand the intents of the tutor andreproduce the same behaviors accordingly.

  • 23.
    Fonooni, Benjamin
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Thomas, Hellström
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Applying a Priming Mechanism for Intention Recognition in Shared Control2015Ingår i: 2015 IEEE INTERNATIONAL MULTI-DISCIPLINARY CONFERENCE ON COGNITIVE METHODS IN SITUATION AWARENESS AND DECISION SUPPORT (COGSIMA), 2015, s. 35-41Konferensbidrag (Refereegranskat)
    Abstract [en]

    In many robotics shared control applications, users are forced to focus hard on the robot due to the task’s high sensitivity or the robot’s misunderstanding of the user’s intention. This brings frustration and dissatisfaction to the user and reduces overall efficiency. The user’s intention is sometimes unclear and hard to identify without some kind of bias in the identification process. In this paper, we present a solution in which an attentional mechanism helps the robot to recognize the user’s intention. The solution uses a priming mechanism and parameterized behavior primitives to support intention recognition and improve shared control for teleoperation tasks.

  • 24.
    Fonooni, Benjamin
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Thomas, Hellström
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    On the Similarities Between Control Based and Behavior Based Visual Servoing2015Ingår i: Proceedings of the 30th Annual ACM Symposium on Applied Computing, New York: Association for Computing Machinery (ACM), 2015, s. 320-326Konferensbidrag (Refereegranskat)
    Abstract [en]

    Abstract Robotics is tightly connected to both artificial intelligence (AI) and control theory. Both AI and control based robotics are active and successful research areas, but research is often conducted by well separated communities. In this paper, we compare the two approaches in a case study for the design of a robot that should move its arm towards an object with the help of camera data. The control based approach is a model-free version of Image Based Visual Servoing (IBVS), which is based on mathematical modeling of the sensing and motion task. The AI approach, here denoted Behavior-Based Visual Servoing (BBVS), contains elements that are biologically plausible and inspired by schema-theory. We show how the two approaches lead to very similar solutions, even identical given a few simplifying assumptions. This similarity is shown both analytically and numerically. However, in a simple picking task with a 3 DoF robot arm, BBVS shows significantly higher performance than the IBVS approach, partly because it contains more manually tuned parameters. While the results obviously do not apply to all tasks and solutions, it illustrates both strengths and weaknesses with both approaches, and how they are tightly connected and share many similarities despite very different starting points and methodologies.

  • 25.
    Fonooni, Benjamin
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Thomas, Hellström
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Janlert, Lars-Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Priming as a means to reduce ambiguity in learning from demonstration2016Ingår i: International Journal of Social Robotics, ISSN 1875-4791, E-ISSN 1875-4805, Vol. 8, nr 1, s. 5-19Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Learning from Demonstration (LfD) is an established robot learning technique by which a robot acquires a skill by observing a human or robot teacher demonstrating the skill. In this paper we address the ambiguity involved in inferring the intention with one or several demonstrations. We suggest a method based on priming, and a memory model with similarities to human learning. Conducted experiments show that the developed method leads to faster and improved understanding of the intention with a demonstration by reducing ambiguity.

  • 26.
    Freidovich, Leonid
    Michigan State University.
    Constrained joint PD plus controller for flexible link robots2000Konferensbidrag (Refereegranskat)
    Abstract [en]

    A class of globally asymptotically stable regulators for a finite-dimensional model of robot arm with flexible links under gravity is presented. The control law is formed as the sum of static compensation of gravity at the desired position and constrained state feedback. Only some of generalized coordinates (joint positions and velocities) are assumed available for measurement and saturation in amplifier characteristic curves is taken into account. Copyright (C) 2000 IFAC.

  • 27.
    Freidovich, Leonid
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Control methods for robotic applications: lecture notes2013Bok (Övrigt vetenskapligt)
  • 28.
    Freidovich, Leonid
    et al.
    Michigan State University.
    Khalil, Hassan K.
    Michigan State University.
    Universal integral controllers for robotic manipulators2002Ingår i: Nonlinear control systems 2001: (NOLCOS2001) : a proceeding volume from the 5th IFAC Symposium, St. Petersburg, Russia, 4-6 July 2001, Oxford: Pergamon Press, 2002, s. 351-356Konferensbidrag (Refereegranskat)
    Abstract [en]

    As a standard model for a rigid multilink robotic manipulator, we consider a MIMO nonlinear system of uniform vector relative degree {2,...,2}, which has a globally defined normal form with no zero dynamics. We consider a trajectory-following problem for a class of smooth bounded time-varying vector reference signals. We design an output feedback integral controller that ensures ultimately bounded tracking error which could be made as small as required. In addition, if the reference signal has a constant limit, the output approaches this limit. The controller is robust with respect to parameter uncertainties, decentralized, saturated, and simple to implement. Locally, it is a PID regulator with derivatives estimated via a linear high-gain observer. Regional (and semiglobal) practical (and asymptotic) stability is shown with the help of a vector Lyapunov function and a technique, typical for "continuous" sliding mode control. Copyright (C) 2001 IFAC.

  • 29.
    Freidovich, Leonid
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Shiriaev, Anton
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Gomez-Estern, Fabio
    Gordillo, Francisco
    Aracil, Javier
    Modification via averaging of partial-energy-shaping control for orbital stabilization: cart-pendulum example2006Ingår i: Proceedings of the 45th IEEE conference on decision and control, vols 1-14, New York: IEEE Press, 2006, s. 6150-6155Konferensbidrag (Refereegranskat)
    Abstract [en]

    We consider the problem of creating oscillations with respect to a part of state variables in underactuated mechanical systems. The main contribution is a modification of a recently proposed control strategy, exploiting passivity to shape the energy of the system with respect to a subset of the state variables and neglecting the dynamics of the other ones. We propose a way to design an additional control action, which guarantees boundedness of the motion of these other degrees of freedom, which otherwise almost always evolve without any bound. The idea is presented on the well-known two-degrees-of-freedom benchmark example of inverted pendulum on a cart.

  • 30.
    Grönskog, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Designhögskolan vid Umeå universitet.
    Tangible toolkit for process industry2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The process industry is the subject of increasing automation. As a step in this direction, the control of whole industrial plants has been centralized into small rooms. Here the process can be monitored and manually controlled if needed. The few operators still employed are expressing boredom due to everything being automated and feeling disconnected from the industrial environment where the work is carried out.

    By introducing tangibles into the control environment, that gap between factory floor and control room can be breached. Through simulating the rich experience of the production process, the operators could be engaged to work together with the automation software.

    Field research was done together with the project partners ABB and Swedish ICT. It provided a first hand experience of the context, the users and their problems. Working with a HCD approach, quickly prototyped solutions were discussed with users and stakeholders in the project.

    The result is a number of tangibles that utilizes their physical form and contemporary research in the field. This creates a stronger relationship between the operators and their equipment, gaining both an intuitive understanding and a tool for directly manipulating the equipment they control. The result cannot be discussed in greater detail due to patenting inquiries. 

  • 31. Gusev, Sergei V.
    et al.
    Shiriaev, Anton S.
    Freidovich, Leonid B.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    SDP-based approximation of stabilising solutions for periodic matrix Riccati differential equations2016Ingår i: International Journal of Control, ISSN 0020-7179, E-ISSN 1366-5820, Vol. 89, nr 7, s. 1396-1405Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Numerically finding stabilising feedback control laws for linear systems of periodic differential equations is a nontrivial task with no known reliable solutions. The most successful method requires solving matrix differential Riccati equations with periodic coefficients. All previously proposed techniques for solving such equations involve numerical integration of unstable differential equations and consequently fail whenever the period is too large or the coefficients vary too much. Here, a new method for numerical computation of stabilising solutions for matrix differential Riccati equations with periodic coefficients is proposed. Our approach does not involve numerical solution of any differential equations. The approximation for a stabilising solution is found in the form of a trigonometric polynomial, matrix coefficients of which are found solving a specially constructed finite-dimensional semidefinite programming (SDP) problem. This problem is obtained using maximality property of the stabilising solution of the Riccati equation for the associated Riccati inequality and sampling technique. Our previously published numerical comparisons with other methods shows that for a class of problems only this technique provides a working solution. Asymptotic convergence of the computed approximations to the stabilising solution is proved below under the assumption that certain combinations of the key parameters are sufficiently large. Although the rate of convergence is not analysed, it appeared to be exponential in our numerical studies.

  • 32.
    Hallén, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Comminution control using reinforcement learning: Comparing control strategies for size reduction in mineral processing2018Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In mineral processing the grinding comminution process is an integral part since it is often the bottleneck of the concentrating process, thus small improvements may lead to large savings. By implementing a Reinforcement Learning controller this thesis aims to investigate if it is possible to control the grinding process more efficiently compared to traditional control strategies. Based on a calibrated plant simulation we compare existing control strategies with Proximal Policy Optimization and show possible increase in profitability under certain conditions.

  • 33.
    Hallén, Mattias
    et al.
    ABB Corporate Research.
    Åstrand, Max
    ABB Corporate Research.
    Sikström, Johannes
    Boliden.
    Servin, Martin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Reinforcement Learning for Grinding Circuit Control in Mineral Processing2019Konferensbidrag (Refereegranskat)
    Abstract [en]

    Grinding, i.e. reducing the particle size of mined ore, is often the bottleneck of the mining concentrating process. Thus, even small improvements may lead to large increases in profit. The goal of the grinding circuit is two-sided; to maximize the throughput of ore, and minimize the resulting particle size of the ground ore within some acceptable range. In this work we study the control of a two-stage grinding circuit using reinforcement learning. To this end, we present a solution for integrating industrial simulation models into the reinforcement learning framework OpenAI Gym. We compare an existing PID controller, based on vast domain knowledge and years of hand-tuning, with a black-box algorithm called Proximal Policy Optimization on a calibrated grinding circuit simulation model. The comparison show that it is possible to control the grinding circuit using reinforcement learning. In addition, contrasting reinforcement learning from the existing PID control, the algorithm is able tomaximize an abstract control goal: maximizing profit as defined by a profit function given by our industrial collaborator. In some operating cases the algorithm is able to control the plant more efficiently compared to existing control.

  • 34.
    Hellman, David
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Managing the Expectations of Voice-Controlled Access Solutions2019Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Röst är den primära kommunikationskällan för de flesta människorna på jorden. Förmågan att bearbeta tal är något människor föds med, vilket gör att interaktion genom röst kräver liten kognitiv ansträngning. Framsteg inom röstteknologi under de senaste 20 åren har lett till ett ökat utbud av röststyrda applikationer. För många av dessa röststyrda applikationer existerar en risk att falska förväntningar leder till avsevärt försämrad interaktion. Ett av många applikationsområden där röst börjar framträda är accesslösningar såsom smarta lås. Med sitt fundamentala värde att hålla människor och deras tillgångar trygga och säkra utan att kompromissa enkelheten, kräver utformningen av accesslösningar flera delikata beslut. Därmed har studien ämnat att utvärdera hur användares förväntningar på röststyrda accesslösningar påverkas av röstattribut. För att undersöka och öka förståelsen av röstteknologi och de psykologiska effekterna av tal, genomfördes en litteraturstudie av existerande forskning initialt. Baserat på fynden i litteraturstudien startades sedan en designprocess för utveckling av ett röstgränssnitt. Erkända metoder användes för framtagandet av ett användarvänligt gränssnitt. Designprocessen låg till grund för ett Wizard of Oz test där olika konversationsstrategier och röster påverkade förväntningar av och uppfattningen av ett röststyrt smart lås. Resultaten visar att det är fundamentalt att välja en passande konversationsstil för att ge användare en känsla av kontroll. Studien påvisade även hur tidigare erfarenheter av röststyrda applikationer påverkar förväntningar av andra röststyrda applikationer och gör dem mer eller mindre personliga. Vidare diskuteras etiska avvägningar som måste göras när man designar röstgränssnitt som ska medföra användarvärde och inte inskränka användarnas integritet.

  • 35.
    Hellström, Thomas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    An intelligent rollator with steering by braking2012Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Walking aids such as rollators help a lot of individuals to maintain mobility and independence. While these devices clearly improve balance and mobility they also lead to increased risk of falling accidents. With an increasing proportion of elderly in the population, there is a clear need for improving these devices. This paper describes ongoing work on the development of ROAR - an intelligent rollator that can help users with limited vision, cognition or motoric abilities. Automatic detection and avoidance of obstacles such as furniture and doorposts simplify usage in cluttered indoor environments. For outdoors usage, the design includes a function to avoid curbs and other holes that may otherwise cause serious accidents. Ongoing work includes a novel approach to compensate for sideway drift that occur both indoors and outdoors for users with certain types of cognitive or motoric disabilities. Also the control mechanism differs from other similar designs. Steering is achieved by activating electrical brakes instead of turning the front wheels. Furthermore, cheap infrared sensors are used instead of a laser scanner for detection of objects.  Altogether, the design is believed to lead to increased acceptability, lower price and safer operation.

  • 36.
    Hellström, Thomas
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Bensch, Suna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för datavetenskap.
    Modeling Interaction for Understanding in HRI2018Ingår i: Proceedings of Explainable Robotic Systems Workshop at HRI 2018, Chicago, USA, March 2018, 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    As robots become more and more capable and autonomous, there is an increased need for humans to understand what the robots do and think. In this paper we investigate what such understanding means and includes, and how robots are and can be designed to support understanding. We present a model of interaction for understanding. The aim is to provide a uniform formal understanding of the large body of existing work, and also to support continued work in the area.

  • 37.
    Khan, Muhammad Sikandar Lal
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Li, Haibo
    KTH.
    Réhman, Shafiq ur
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Embodied tele-presence system (ETS): designing tele-presence for video teleconferencing2014Ingår i: Design, user experience, and usability: User experience design for diverse interaction platforms and environments / [ed] Aaron Marcus, Springer International Publishing Switzerland, 2014, Vol. 8518, s. 574-585Konferensbidrag (Refereegranskat)
    Abstract [en]

    In spite of the progress made in tele conferencing over the last decades, however, it is still far from a resolved issue. In this work, we present an intuitive video teleconferencing system, namely - Embodied Tele-Presence System (ETS) which is based on embodied interaction concept. This work proposes the results of a user study considering the hypothesis: “ Embodied interaction based video conferencing system performs better than the standard video conferencing system in representing nonverbal behaviors, thus creating a ‘feeling of presence’ of a remote person among his/her local collaborators”. Our ETS integrates standard audio-video conferencing with mechanical embodiment of head gestures of a remote person (as nonverbal behavior) to enhance the level of interaction. To highlight the technical challenges and design principles behind such tele-presence systems, we have also performed a system evaluation which shows the accuracy and efficiency of our ETS design. The paper further provides an overview of our case study and an analysis of our user evaluation. The user study shows that the proposed embodied interaction approach in video teleconferencing increases ‘in-meeting interaction’ and enhance a ‘feeling of presence’ among remote participant and his collaborators.

  • 38.
    Khan, Muhammad Sikandar Lal
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Li, Haibo
    ur Réhman, Shafiq
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Gaze perception and awareness in smart devices2016Ingår i: International journal of human-computer studies, ISSN 1071-5819, E-ISSN 1095-9300, Vol. 92-93, s. 55-65Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Eye contact and gaze awareness play a significant role for conveying emotions and intentions duringface-to-face conversation. Humans can perceive each other's gaze quite naturally and accurately. However,the gaze awareness/perception are ambiguous during video teleconferencing performed by computer-based devices (such as laptops, tablet, and smart-phones). The reasons for this ambiguity are the(i) camera position relative to the screen and (ii) 2D rendition of 3D human face i.e., the 2D screen isunable to deliver an accurate gaze during video teleconferencing. To solve this problem, researchers haveproposed different hardware setups with complex software algorithms. The most recent solution foraccurate gaze perception employs 3D interfaces, such as 3D screens and 3D face-masks. However, todaycommonly used video teleconferencing devices are smart devices with 2D screens. Therefore, there is aneed to improve gaze awareness/perception in these smart devices. In this work, we have revisited thequestion; how to improve a remote user's gaze awareness among his/her collaborators. Our hypothesis isthat ‘an accurate gaze perception can be achieved by the ‘3D embodiment’ of a remote user's head gestureduring video teleconferencing’. We have prototyped an embodied telepresence system (ETS) for the 3Dembodiment of a remote user's head. Our ETS is based on a 3-DOF neck robot with a mounted smartdevice (tablet PC). The electromechanical platform in combination with a smart device is a novel setupthat is used for studying gaze awareness/perception in 2D screen-based smart devices during videoteleconferencing. Two important gaze-related issues are considered in this work; namely (i) ‘Mona-LisaGaze Effect’ – the gaze is always directed at the person independent of his position in the room, and (ii)‘Gaze Awareness/Faithfulness’ – the ability to perceive an accurate spatial relationship between theobserving person and the object by an actor. Our results confirm that the 3D embodiment of a remoteuser head not only mitigates the Mona Lisa gaze effect but also supports three levels of gaze faithfulness,hence, accurately projecting the human gaze in distant space.

  • 39.
    Khan, Muhammad Sikandar Lal
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Li, Haibo
    ur Réhman, Shafiq
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Telepresence Mechatronic Robot (TEBoT): Towards the design and control of socially interactive bio-inspired system2016Ingår i: Journal of Intelligent & Fuzzy Systems, ISSN 1064-1246, E-ISSN 1875-8967, Vol. 31, nr 5, s. 2597-2610Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Socially interactive systems are embodied agents that engage in social interactions with humans. From a design perspective, these systems are built by considering a biologically inspired design (Bio-inspired) that can mimic and simulate human-like communication cues and gestures. The design of a bio-inspired system usually consists of (i) studying biological characteristics, (ii) designing a similar biological robot, and (iii) motion planning, that can mimic the biological counterpart. In this article, we present a design, development, control-strategy and verification of our socially interactive bio-inspired robot, namely - Telepresence Mechatronic Robot (TEBoT). The key contribution of our work is an embodiment of a real human-neck movements by, i) designing a mechatronic platform based on the dynamics of a real human neck and ii) capturing the real head movements through our novel single-camera based vision algorithm. Our socially interactive bio-inspired system is based on an intuitive integration-design strategy that combines computer vision based geometric head pose estimation algorithm, model based design (MBD) approach and real-time motion planning techniques. We have conducted an extensive testing to demonstrate effectiveness and robustness of our proposed system.

  • 40.
    Khan, Muhammad Sikandar Lal
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    ur Réhman, Shafiq
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Embodied head gesture and distance education2015Ingår i: 6th International Conference on Applied Human Factors and Ergonomics (AHFE 2015) and the Affiliated Conferences, 2015, Vol. 3, s. 2034-2041Konferensbidrag (Refereegranskat)
    Abstract [en]

    Traditional distance education settings are usually based on video teleconferencing scenarios where human emotions and social presence are only expressed by the facial and vocal expressions which are not enough for complete presence; our bodily gestures and actions play a vital role in understanding exact meaning of communication patterns; especially in teaching-learning scenarios. The bodily gestures especially head movements offer cues to understand contextual knowledge during conversational dialogue. In this work, we have considered the tutor’s head gesture embodiment for educational assistive robot and compared the results with the standard audio-video tele-conferencing scenarios used in online education. We have used Embodied Telepresence System (ETS) to investigate the distance communication for online education setting. Our ETS emulates the head gestures of the human tutor for distance education scenario. Our experimental study includes ten able-bodied subjects (5 male and 5 female) from various countries. These participants were asked to participate in online education scenario through i) a traditional video conferencing tool, i.e. Skype and ii) an extended setup based on ETS. The statistical analysis is done on the results which indicates the effectiveness of our novel embodied head gesture based approach in distance education setting. Our experimental studies show that the proposed design of embodied head gesture based ETS is able to improve the user engagement in distance education.

  • 41.
    Khan, Muhammad Sikandar Lal
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    ur Réhman, Shafiq
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    La Hera, Pedro
    Liu, Feng
    Li, Haibo
    A pilot user's prospective in mobile robotic telepresence system2014Ingår i: 2014 Asia-Pacific Signal and Information Processing Association Annual Summit and Conference (APSIPA 2014), IEEE, 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this work we present an interactive video conferencing system specifically designed for enhancing the experience of video teleconferencing for a pilot user. We have used an Embodied Telepresence System (ETS) which was previously designed to enhance the experience of video teleconferencing for the collaborators. In this work we have deployed an ETS in a novel scenario to improve the experience of pilot user during distance communication. The ETS is used to adjust the view of the pilot user at the distance location (e.g. distance located conference/meeting). The velocity profile control for the ETS is developed which is implicitly controlled by the head of the pilot user. The experiment was conducted to test whether the view adjustment capability of an ETS increases the collaboration experience of video conferencing for the pilot user or not. The user study was conducted in which participants (pilot users) performed interaction using ETS and with traditional computer based video conferencing tool. Overall, the user study suggests the effectiveness of our approach and hence results in enhancing the experience of video conferencing for the pilot user.

  • 42.
    Källman, Axel
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Go & Grab: Flexibel robotarm med ballistiskt gripdon2018Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta projekt agerar som ett test av en prototyp av en robot med en ny utformning, med fokus på accessoarer till denna robot. Denna robot mobila robot är en differentialstyrd robot med en vagn, fast släpet är framtill på roboten. Detta projekt innehåller konstruktion, implementation och test av två gripdon som monteras på vagnen. En lift konstrueras och monteras på vagnen som gripdonen i sin tur monteras på för att kunna vara flexibel i vilka höjder den kan gripa objekt på. Utöver liften och gripdonen så görs även vagnen som detta monteras på tillsammans med leden som håller ihop vagnen och roboten.

    Detta projekt genomfördes med en divide and conquer metodik som delar upp ett problem i mindre projekt och angriper dem ett i taget i en ordning för vilket som prioriterades högst. Leden var den första delen att tillverkas, följt av två gripdon och sist liften. Efter att dessa delar var tillverkade och monterade så testades roboten ihop med vagnen att köras och den fick utföra en del olika tester. Därefter utvärderades resultaten.

    Testresultaten var positiva och lovande. Leden och liften går till viss del att förbättra men det fungerade alldeles perfekt för denna implementation av roboten. Gripdonen funkar fast med vissa svårigheter, de behöver lite förbättringar på roboten som gör att den har lite mer precision och hastighet. Resultaten för gripdonen är varierande beroende på vad gripobjektet var.

  • 43.
    La Hera, Pedro M
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Mettin, Uwe
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Westerberg, Simon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Shiriaev, Anton S
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Modeling and control of hydraulic rotary actuators used in forestry cranes2009Ingår i: ICRA: 2009 IEEE international conference on robotics and automation, vols 1-7, 2009, s. 2161-2166Konferensbidrag (Refereegranskat)
    Abstract [en]

    The steps for modeling and control of a hydraulic rotary actuator are discussed. Our aim is to present experimental results working with a particular sensing device for angular position as a complement to pressure sensing devices. We provide the steps in experimental system identification used for modeling the system dynamics. The cascade controller designed contains an inner loop for an accurate tracking of torque while stabilizing position reference trajectories. The performance of this design is experimentally verified.

  • 44. La Hera, Pedro
    et al.
    Morales, Daniel Ortiz
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Model-Based Development of Control Systems for Forestry Cranes2015Ingår i: Journal of Control Science and Engineering, ISSN 1687-5249, E-ISSN 1687-5257, Vol. 2015, artikel-id 256951Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Model-based methods are used in industry for prototyping concepts based on mathematical models. With our forest industry partners, we have established a model-based workflow for rapid development of motion control systems for forestry cranes. Applying this working method, we can verify control algorithms, both theoretically and practically. This paper is an example of this workflow and presents four topics related to the application of nonlinear control theory. The first topic presents the system of differential equations describing the motion dynamics. The second topic presents nonlinear control laws formulated according to sliding mode control theory. The third topic presents a procedure for model calibration and control tuning that are a prerequisite to realize experimental tests. The fourth topic presents the results of tests performed on an experimental crane specifically equipped for these tasks. Results of these studies show the advantages and disadvantages of these control algorithms, and they highlight their performance in terms of robustness and smoothness.

  • 45.
    La Hera, Pedro
    et al.
    Sveriges lantbruksuniversitet .
    Ortiz Morales, Daniel
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Designing and testing control systems for forestry cranesManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Motivated by the interest, and in collaboration of forestry machine manufacturers, a number of motion control algorithms have been designed, implemented, and tested in a forwarder crane. The aim has been to achieve the robust tracking of reference link motion trajectories based on sensory feedback coming from pressure and angular displacement sensors mounted in the manipulator. To this end, a procedure employing computer aided model-based methods and simulation technology have been suggested, in order to produce systematical tools for model analysis, tuning of controllers, and rapid prototyping for hardware-in-the-loop testing. The controllers derived have the objective to form the background of a new generation of crane control modes, which will be subsequently designed by the use of different motion planning techniques. We present results of experimental studies carried out on a medium-size crane, which has been properly equipped for the task of rapid-prototyping.

  • 46.
    La Hera, Pedro
    et al.
    Sveriges lantbruksuniversitet .
    Ortiz Morales, Daniel
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Non-linear dynamics modelling description for simulating the behavior of forestry cranes2014Ingår i: International journal of Modeling, identification and control, ISSN 1746-6172, E-ISSN 1746-6180, Vol. 21, nr 2, s. 125-138Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Model-based design is a standard framework widely adopted in modern industry. It is used for designing multi-domain engineering solutions based on computer-aided simulation technology. Currently, this approach is also being viewed as a tentative method for designing modern heavy-duty machine technology. Under this motivation, our aim is to present how modeling techniques can be used for simulating dynamics of forestry machines. To this end, we consider a forestry crane, and propose mathematical models and calibration techniques, such that model-based methods can subsequently be applied. The complexity of the machine is represented by first principle laws, in which the mechanical system is modeled by Euler-Lagrange formulations, and the hydraulic system is modeled by principles of fluid dynamics. The calibration algorithms are performed by statistical algorithms based on linear and nonlinear least-squares methods. The results of simulation show a significant correspondence between the simulated and observed variables, validating our procedures.

  • 47.
    La Hera, Pedro
    et al.
    Swedish University of Agricultural Sciences, Umeå, Sweden.
    Rehman, Bilal Ur
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Morales, Daniel Ortiz
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Electro-hydraulically actuated forestry manipulator: Modeling and Identification2012Ingår i: 2012 IEEE/RSJ Iinternational Conference on Intelligent Robots and Systems (IROS), New York: IEEE conference proceedings, 2012, s. 3399-3404Konferensbidrag (Refereegranskat)
    Abstract [en]

    We present results of modeling dynamics of a forestry manipulator, in which we consider its mechanics, as well as its hydraulic actuation system. The mathematical model of its mechanics is formulated by Euler-Lagrange equations, for which the addition of friction forces is straightforward. Dynamics of the hydraulic system is modeled upon first principle laws, which concern flow through orifices and fluid compressibility. These models lead to a set of equations with various unknown parameters, which are related to the inertias, masses, location of center of masses, friction forces, and valve coefficients. The numerical values of these parameters are estimated by the use of least-square methods, which is made feasible by transforming the models into linear representations. The results of simulation tests show a significant correspondence between measured and estimated variables, validating our modeling and identification approach.

  • 48.
    La Hera, Pedro
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. SLU, Dept Forestry Technol, Umeå, Sweden and Swedish Cluster Forest Technol, Vindeln, Sweden.
    Shiriaev, Anton S.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Norwegian Univ Sci & Technol, Dept Engn Cybernet, Trondheim, Norway.
    Freidovich, Leonid B
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Mettin, Uwe
    Gusev, Sergey V.
    Stable walking gaits for a three-link planar biped robot with one actuator2013Ingår i: IEEE Transactions on robotics, ISSN 1552-3098, E-ISSN 1941-0468, IEEE transactions on robotics, Vol. 29, nr 3, s. 589-601Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We consider a benchmark example of a three-link planar biped walker with torso, which is actuated in between the legs. The torso is thought to be kept upright by two identical torsional springs. The mathematical model reflects a three-degree-of-freedom mechanical system with impulse effects, which describe the impacts of the swing leg with the ground, and the aim is to induce stable limit-cycle walking on level ground. The main contribution is a novel systematic trajectory planning procedure for solving the problem of gait synthesis. The key idea is to find a system of ordinary differential equations for the functions describing a synchronization pattern for the time evolution of the generalized coordinates along a periodic motion. These functions, which are known as virtual holonomic constraints, are also used to compute an impulsive linear system that approximates the time evolution of the subset of coordinates that are transverse to the orbit of the continuous part of the periodic solution. This auxiliary system, which is known as transverse linearization, is used to design a nonlinear exponentially orbitally stabilizing feedback controller. The performance of the closed-loop system and its robustness with respect to various perturbations and uncertainties are illustrated via numerical simulations.

  • 49.
    La Hera, Pedro X
    et al.
    Swedish University of Agricultural Sciences.
    Ortíz Morales, Daniel
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Modeling dynamics of an electro-hydraulic servo actuated manipulator: A case study of a forestry forwarder crane2012Ingår i: World Automation Congress (WAC), 2012, 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    System modeling and parameters estimation are key elements to realize model-based control. Here, we present a discussion of modeling dynamics of a forestry forwarder crane, for which standard Euler-Lagrange formulations are used to describe its equations of motion. To calibrate this model according to experimental data, we perform parameter estimation based on the method of least squares. This procedure allows identifying various unknown parameters, which are related to the inertias, masses, location of center of masses, and friction forces coefficients. The results of simulation tests show a significant correspondence between measured and estimated variables, validating our modeling approach.

  • 50.
    Li, Songyu
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    A NEW HANDS-FREE FACETO FACE VIDEOCOMMUNICATION METHOD: Profile based frontal face videoreconstruction2018Självständigt arbete på avancerad nivå (masterexamen), 80 poäng / 120 hpStudentuppsats (Examensarbete)
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