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Performance evaluation and development of a synchro-drive mobile robot
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Nwufoh, Charles Nnonyelum J. (1992) Performance evaluation and development of a synchro-drive mobile robot. PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b3251639~S15
Abstract
The work described in this thesis is concerned with the performance of the mechanical system of a mobile robot that is capable of omnidirectional motion. The main attribute of such mobile robots is that their direction of motion is independent of chassis orientation. This attribute endows them with exceptional manoeuvrability, but it is also found to pose substantial problems by changing the level of accuracy and stability of the robot as its direction of travel changes.
The main objective of the research is to conduct a detailed evaluation of the performance of a mobile robot which is capable of omnidirectional movement achieved by means of a synchronized all-wheel steering and all-wheel drive (Synchro-drive) technique. The objective is met by comparing the synchro-drive method with other configurations used for mobile robots, by comparing different designs of the synchro-drive method and by analyzing synchro-drive mechanical behaviour in response to drive and steering inputs. A kinematic model of the synchro-drive arrangement is formulated and this is used to analyze different designs and to assess the limits of the control variables beyond which a Synchro-Drive Mobile Robot (SDMR) operation will become unstable. A new version of the synchro-drive arrangement was developed and was used to perform extensive practical testing in order to determine factors affecting positional accuracy and the trajectory actually executed by the mobile robot.
The analysis of the boundaries of the control space revealed the limits on acceleration which may be allowed by the robot's control system for it to remain stable. It also showed that the acceleration limits depend on the angle between the wheel heading and the chassis orientation, which is defined as the robot's posture. Practical experimentation identified the major influences on robot accuracy and also related the form, magnitude and direction of these errors to the robot's posture. The experiments revealed that the errors were due partly to aspects of the design itself and partly due to inevitable errors in the complete mechanical system. A continuous position error correction method is proposed which uses experimental data as the basis for correction. Correction quantities vary with posture, and the method uses a modification to the steering rate to minimize trajectory error.
Overall the study reveals the factors which must be considered to enable the potential of the synchro-drive mobile robot to be fully realized.
| Item Type: | Thesis (PhD) | ||||
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| Subjects: | T Technology > TJ Mechanical engineering and machinery | ||||
| Library of Congress Subject Headings (LCSH): | Mobile robots -- Design and construction, Mobile robots -- Chassis, Mobile robots -- Steering | ||||
| Official Date: | 1992 | ||||
| Dates: |
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| Institution: | University of Warwick | ||||
| Theses Department: | Department of Engineering | ||||
| Thesis Type: | PhD | ||||
| Publication Status: | Unpublished | ||||
| Supervisor(s)/Advisor: | Goodhead, T. C. | ||||
| Extent: | vi, 314 leaves : illustrations, charts | ||||
| Language: | eng |
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