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  • 1. 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.

  • 2.
    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.

  • 3.
    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.

  • 4.
    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.

  • 5.
    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.

  • 6.
    Mettin, Uwe
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    La Hera, Pedro X.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Ortiz Morales, Daniel
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Shiriaev, Anton
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Freidovich, Leonid
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Westerberg, Simon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Trajectory planning and time-independent motion control for a kinematically redundant hydraulic manipulator2009Ingår i: Advanced Robotics, 2009. ICAR 2009. International Conference on, IEEE conference proceedings, 2009, s. 1-6Konferensbidrag (Refereegranskat)
    Abstract [en]

    In this paper we consider the problem of motion planning and control of a kinematically redundant manipulator, which is used on forestry machines for logging. Once a desired path is specified in the 3D world frame, a trajectory can be planned and executed such that all joints are synchronized and constrained to the Cartesian path. We introduce an optimization procedure that takes advantage of the kinematic redundancy so that time-efficient joint and velocity profiles along the path can be obtained. Differential constraints imposed by the manipulator dynamics are accounted for by employing a phase-plane technique for admissible path timings. In hydraulic manipulators, such as considered here, the velocity constraints of the individual joints are particularly restrictive. We suggest a time-independent control scheme for the planned trajectory which is built upon the standard reference tracking controllers. Experimental tests underline the benefits and efficiency of the model-based trajectory planning and show success of the proposed control strategy.

  • 7.
    Ortiz Morales, Daniel
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Virtual Holonomic Constraints: from academic to industrial applications2015Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Whether it is a car, a mobile phone, or a computer, we are noticing how automation and production with robots plays an important role in the industry of our modern world. We find it in factories, manufacturing products, automotive cruise control, construction equipment, autopilot on airplanes, and countless other industrial applications.

            Automation technology can vary greatly depending on the field of application. On one end, we have systems that are operated by the user and rely fully on human ability. Examples of these are heavy-mobile equipment, remote controlled systems, helicopters, and many more. On the other end, we have autonomous systems that are able to make algorithmic decisions independently of the user.

            Society has always envisioned robots with the full capabilities of humans. However, we should envision applications that will help us increase productivity and improve our quality of life through human-robot collaboration. The questions we should be asking are: “What tasks should be automated?'', and “How can we combine the best of both humans and automation?”. This thinking leads to the idea of developing systems with some level of autonomy, where the intelligence is shared between the user and the system. Reasonably, the computerized intelligence and decision making would be designed according to mathematical algorithms and control rules.

            This thesis considers these topics and shows the importance of fundamental mathematics and control design to develop automated systems that can execute desired tasks. All of this work is based on some of the most modern concepts in the subjects of robotics and control, which are synthesized by a method known as the Virtual Holonomic Constraints Approach. This method has been useful to tackle some of the most complex problems of nonlinear control, and has enabled the possibility to approach challenging academic and industrial problems. This thesis shows concepts of system modeling, control design, motion analysis, motion planning, and many other interesting subjects, which can be treated effectively through analytical methods. The use of mathematical approaches allows performing computer simulations that also lead to direct practical implementations.

  • 8.
    Ortiz Morales, Daniel
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    La Hera, Pedro
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Mettin, Uwe
    Department of Engineering Cybernetics, Norwegian University of Science and Technology.
    Freidovich, Leonid
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Shiriaev, Anton
    Department of Engineering Cybernetics, Norwegian University of Science and Technology.
    Westerberg, Simon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Steps in trajectory planning and controller design for a hydraulically driven crane with limited sensing2010Ingår i: IEEE International Conference on Intelligent Robots and Systems, IEEE conference proceedings, 2010, s. 3836-3841Konferensbidrag (Refereegranskat)
    Abstract [en]

    In the forest industry, trees are logged and harvested by human-operated hydraulic manipulators. Eventually, these tasks are expected to be automated with optimal performance. However, with todays technology the main problem is implementation. While prototypes may have rich sensing information, real cranes lack certain sensing devices, such as encoders for position sensing. Automating these machines requires unconventional solutions. In this paper, we consider the motion planning problem, which involves a redesign of optimal trajectories, so that open loop control strategies can be applied using feed-forward control signals whenever sensing information is not available.

  • 9.
    Ortiz Morales, Daniel
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    La Hera, Pedro
    Sveriges lantbruksuniversitet .
    Ur Rehman, Shafiq
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Generating Periodic Motions for the Butterfly Robot2013Ingår i: Intelligent Robots and Systems (IROS), 2013 IEEE/RSJ International Conference on / [ed] Amato, N., IEEE conference proceedings, 2013, s. 2527-2532Konferensbidrag (Refereegranskat)
    Abstract [en]

    We analyze the problem of dynamic non-prehensile manipulation by considering the example of thebutterfly robot. Our main objective is to study the problem of stabilizing periodic motions, which resemble some form of juggling acrobatics. To this end, we approach the problem by considering theframework of virtual holonomic constraints. Under this basis, we provide an analytical and systematic solution to the problems of trajectory planning and design of feedback controllers to guarantee orbital exponential stability. Results are presented in the form of simulation tests.

  • 10.
    Ortiz Morales, Daniel
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    La Hera, Pedro
    Sveriges lantbruksuniversitet .
    Westerberg, Simon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Freidovich, Leonid
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Shiriaev, Anton
    Norwegian University of Science and Technology.
    Path-constrained motion analysis: an algorithm to understand human performance on hydraulic manipulators2015Ingår i: IEEE Transactions on Human-Machine Systems, ISSN 2168-2291, Vol. 45, nr 2, s. 187-199Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We propose a novel method to analyze how human operators use hydraulic manipulators of heavy-duty equipment. The approach is novel in the sense that it applies knowledge of motion planning and optimization techniques used in robotics. As an example, we consider the case of operating a forestry crane. To that end, we use motion data that has been recorded during standard operation with the help of sensors and a data acquisition unit. The data backs up the notion that operators work by performing repeatable patterns observed in the trajectories of the manipulator's joints. We show how this nominal behavior is computed, and consequently this allow us to present the following: 1) an analytical procedure to analyze motions, 2) how to represent the "performance" of the operator in a 2D plot, 3) an example of how to use this information to suggest customized control settings, and 4) some complementary ideas needed for improving efficiency through automation.

  • 11.
    Ortiz Morales, Daniel
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    La Hera, Pedro X
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Design of energy efficient walking gaits for a three-link planar biped walker with two unactuated degrees of freedom2012Ingår i: Robotics and Automation (ICRA), 2012 IEEE International Conference on, New York: IEEE Computer Society, 2012, s. 148-153Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    We consider the example of a three-link planar biped walker with two passive links. The main objective is to design symmetric periodic gaits in flat ground, that can be exponentially stabilized by feedback control. To this end, we apply recent advances in nonlinear control, to propose a systematic procedure to the problems of gait synthesis and control design. The core of the method lays on a nontrivial coordinate transformation, in order to approach the problem in a state-dependent form. For gait synthesis, such procedure allows a reduction of the search space, with the feasibility of considering energetic performance for optimization. For control design, this allows to apply concepts of transverse linearization, to design a nonlinear feedback control law, which performance is studied by numerical simulations.

  • 12.
    Ortiz Morales, Daniel
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Westerberg, Simon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    La Hera, Pedro
    Sveriges lantbruksuniversitet .
    Mettin, Uwe
    Department of Transmission and Hybrid Systems, IAV Automotive Engineering, Berlin, Germany.
    Freidovich, Leonid
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Shiriaev, Anton
    Norwegian University of Science and Technology.
    Increasing the level of automation in the forestry logging process with crane trajectory planning and control2014Ingår i: Journal of Field Robotics, ISSN 1556-4959, E-ISSN 1556-4967, Vol. 31, nr 3, s. 343-363Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Working with forestry machines requires great amount of training to be sufficiently skilledto operate forestry cranes. In view of this, introducing automated motions, as those seenin robotic arms, is ambitioned by this industry for shortening the amount of training timeand make the work of the operator easier. Motivated by this fact, we have developedtwo experimental platforms for testing control systems and motion planning algorithms inreal-time. They correspond to a laboratory setup and a commercial version of a hydraulicmanipulator used in forwarder machines. The aim of this article is to present the results ofthis development by providing an overview of our trajectory planning algorithm and motioncontrol method, with a subsequent view of the experimental results. For motion control,we design feedback controllers that are able to track reference trajectories based on sensormeasurements. Likewise, we provide arguments to design controllers in open-loop for thecase of machines lacking of sensing devices. Relying on the tracking efficiency of thesecontrollers, we design time efficient reference trajectories of motions that correspond tologging tasks. To demonstrate performance, we provide an overview of an extensive testingdone on these machines.

  • 13.
    Ortíz Morales, Daniel
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    La Hera, Pedro X
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Design of stable walking gaits for biped robots with several underactuated degrees of freedom2012Ingår i: Dynamic Walking Conference 2012, Pensacola, Florida, U.S.A., 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    Dynamic walking gaits are theoretically reflected by theperiodic solutions exhibited by nonlinear impulsive dynamicalsystems [1]. In practice, such solutions, knownas limit cycles, can exist either as a natural responseof the system, e.g. passive walkers, or by the use offeedback control. Analytically, finding these solutionsis certainly challenging, and the complexity of the problemincreases considerably if a mixture in between passiveand actuated joints are considered, i.e. underactuatedrobots.

  • 14.
    Ortíz Morales, Daniel
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Westerberg, Simon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    La Hera, Pedro X.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Mettin, Uwe
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. The Department of Engineering Cybernetics, Norwegian University of Science and Technology, Trondheim, Norway.
    Freidovich, Leonid
    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. The Department of Engineering Cybernetics, Norwegian University of Science and Technology, Trondheim, Norway.
    Open-loop control experiments on driver assistance for crane forestry machines2011Ingår i: 2011 IEEE International Conference on Robotics and Automation (ICRA), IEEE conference proceedings, 2011, s. 1797-1802Konferensbidrag (Refereegranskat)
    Abstract [en]

    A short term goal in the forest industry is semi-automation of existing machines for the tasks of logging and harvesting. One way to assist drivers is to provide a set of predefined trajectories that can be used repeatedly in the process. In recent years much effort has been directed to the design of control strategies and task planning as part of this solution. However, commercialization of such automatic schemes requires the installation of various sensing devices, computers and most of all a redesign of the machine itself, which is currently undesired by manufacturers. Here we present an approach of implementing predefined trajectories in an open-loop fashion, which avoids the complexity of sensor and computer integration. The experimental results are carried out on a commercial hydraulic crane to demonstrate that this solution is feasible in practice.

1 - 14 av 14
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