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Modeling of head orientation for applications in manipulator control
Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. (Robotics and Control Lab)
Norwegian University of Science and Technology.
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Many heavy equipment manipulators, such as those found on excavators and forestry machines, currently require continuous manual control. While full automation of these systems is complicated due to the unstructured environments in which they are used, semi-automation can be a useful tool for improving both efficiency and working conditions. In the case of forestry machines, we have located specific work tasks where recent advances in time efficient trajectory planning could be used to increase productivity. However, in order to fully take advantage of these methods, a user interface must be developed that will let the operators communicate their intentions to the system in an intuitive and efficient way. We therefore propose a novel interaction method where headtracking is used to estimate the operator’s gaze in order to specify a target point as input to the trajectory planner for the hydraulic manipulator. In this paper, we investigate the feasibility of such a system, through analysis of task-specific requirements. From dedicated user experiments done in a lab we have identified and tested a model from head orientation to gaze direction, which allows us to predict the gaze angle with an average accuracy of close to 4 degrees. In a field test we have verified that the method is transferable to a real-world setting with comparable results.

National Category
Computer Vision and Robotics (Autonomous Systems)
URN: urn:nbn:se:umu:diva-89066OAI: diva2:718365


Available from: 2014-05-20 Created: 2014-05-20 Last updated: 2014-05-20Bibliographically approved
In thesis
1. Semi-Automating Forestry Machines: Motion Planning, System Integration, and Human-Machine Interaction
Open this publication in new window or tab >>Semi-Automating Forestry Machines: Motion Planning, System Integration, and Human-Machine Interaction
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Delautomatisering av skogsmaskiner : Rörelseplanering, systemintegration och människa-maskin-interaktion
Abstract [en]

The process of forest harvesting is highly mechanized in most industrialized countries, with felling and processing of trees performed by technologically advanced forestry machines. However, the maneuvering of the vehicles through the forest as well as the control of the on-board hydraulic boom crane is currently performed through continuous manual operation. This complicates the introduction of further incremental productivity improvements to the machines, as the operator becomes a bottleneck in the process. A suggested solution strategy is to enhance the production capacity by increasing the level of automation. At the same time, the working environment for the operator can be improved by a reduced workload, provided that the human-machine interaction is adapted to the new automated functionality.

The objectives of this thesis are 1) to describe and analyze the current logging process and to locate areas of improvements that can be implemented in current machines, and 2) to investigate future methods and concepts that possibly require changes in work methods as well as in the machine design and technology. The thesis describes the development and integration of several algorithmic methods and the implementation of corresponding software solutions, adapted to the forestry machine context. Following data recording and analysis of the current work tasks of machine operators, trajectory planning and execution for a specific category of forwarder crane motions has been identified as an important first step for short term automation. Using the method of path-constrained trajectory planning, automated crane motions were demonstrated to potentially provide a substantial improvement from motions performed by experienced human operators. An extension of this method was developed to automate some selected motions even for existing sensorless machines. Evaluation suggests that this method is feasible for a reasonable deviation of initial conditions.

Another important aspect of partial automation is the human-machine interaction. For this specific application a simple and intuitive interaction method for accessing automated crane motions was suggested, based on head tracking of the operator. A preliminary interaction model derived from user experiments yielded promising results for forming the basis of a target selection method, particularly when combined with some traded control strategy. Further, a modular software platform was implemented, integrating several important components into a framework for designing and testing future interaction concepts. Specifically, this system was used to investigate concepts of teleoperation and virtual environment feedback. Results from user tests show that visual information provided by a virtual environment can be advantageous compared to traditional video feedback with regards to both objective and subjective evaluation criteria.

Place, publisher, year, edition, pages
Umeå: Umeå Universitet, 2014. 56 p.
Robotics and control lab, ISSN 1654-5419 ; 6
Forestry Robotics, Forest Machine Automation, Trajectory Planning, Hydraulic Manipulators, Teleoperation, Virtual Environments, Interaction Methods, Head Tracking
National Category
urn:nbn:se:umu:diva-89067 (URN)978-91-7601-061-7 (ISBN)
Public defence
2014-06-11, MIT-huset, MA121, Umeå, 13:00 (English)
Available from: 2014-05-21 Created: 2014-05-20 Last updated: 2014-05-20Bibliographically approved

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Westerberg, SimonShiriaev, Anton S.
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