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Posture control of a low-cost commercially available hexapod robot for uneven terrain locomotion
Dissertation (MEng)--University of Pretoria, 2018.
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| Format: | Thesis |
| Language: | English |
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University of Pretoria
2018
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| _version_ | 1867613515398774784 |
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| access_status_str | Open Access |
| author2 | Theron, Nicolaas J. |
| author_browse | Theron, Nicolaas J. |
| author_facet | Theron, Nicolaas J. |
| collection | Thesis |
| dc_rights_str_mv | © 2018 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MEng)--University of Pretoria, 2018. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/67920 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:37:22.574Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2018 |
| publishDateRange | 2018 |
| publishDateSort | 2018 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/67920 Posture control of a low-cost commercially available hexapod robot for uneven terrain locomotion Theron, Nicolaas J. u10055747@tuks.co.za Tikam, Mayur Unrestricted UCTD Legged robots Hexapod robot Posture control Virtual model control Force control Uneven terrain locomotion Engineering, built environment and information technology theses SDG-09 SDG-09: Industry, innovation and infrastructure Engineering, built environment and information technology theses SDG-11 SDG-11: Sustainable cities and communities Engineering, built environment and information technology theses SDG-08 SDG-08: Decent work and economic growth Dissertation (MEng)--University of Pretoria, 2018. Legged robots hold the advantage on uneven and irregular terrain, where they exhibit superior mobility over other terrestrial, mobile robots. One of the fundamental ingredients in achieving this exceptional mobility on uneven terrain is posture control, also referred to as attitude control. Many approaches to posture control for multi-legged robots have been taken in the literature; however, the majority of this research has been conducted on custom designed platforms, with sophisticated hardware and, often, fully custom software. Commercially available robots hardly feature in research on uneven terrain locomotion of legged robots, despite the significant advantages they pose over custom designed robots, including drastically lower costs, reusability of parts, and reduced development time, giving them the serious potential to be employed as low-cost research and development platforms. Hence, the aim of this study was to design and implement a posture control system on a low-cost, commercially available hexapod robot – the PhantomX MK-II – overcoming the limitations presented by the lower cost hardware and open source software, while still achieving performance comparable to that exhibited by custom designed robots. For the initial controller development, only the case of the robot standing on all six legs was considered, without accounting for walking motion. This Standing Posture Controller made use of the Virtual Model Control (VMC) strategy, along with a simple foot force distribution rule and a direct force control method for each of the legs, the joints of which can only be position controlled (i.e. they do not have torque control capabilities). The Standing Posture Controller was experimentally tested on level and uneven terrain, as well as on a dynamic balance board. Ground truth measurements of the posture during testing exhibited satisfactory performance, which compared favourably to results of similar tests performed on custom designed platforms. Thereafter, the control system was modified for the more general case of walking. The Walking Posture Controller still made use of VMC for the high-level posture control, but the foot force distribution was expanded to also account for a tripod of ground contact legs during walking. Additionally, the foot force control structure was modified to achieve compliance control of the legs during the swing phase, while still providing direct force control during the stance phase, using the same overall control structure, with a simple switching strategy, all without the need for torque control or modification of the motion control system of the legs, resulting in a novel foot force control system for low-cost, legged robots. Experimental testing of the Walking Posture Controller, with ground truth measurements, revealed that it improved the robot’s posture response by a small amount when walking on flat terrain, while on an uneven terrain setup the maximum roll and pitch angle deviations were reduced by up to 28.6% and 28.1%, respectively, as compared to the uncompensated case. In addition to reducing the maximum deviations on uneven terrain, the overall posture response was significantly improved, resulting in a response much closer to that observed on flat terrain, throughout much of the uneven terrain locomotion. Comparing these results to those obtained in similar tests performed with more sophisticated, custom designed robots, it is evident that the Walking Posture Controller exhibits favourable performance, thus fulfilling the aim of this study. mi2025 Mechanical and Aeronautical Engineering MEng Unrestricted SDG-09: Industry, innovation and infrastructure SDG-11: Sustainable cities and communities SDG-08: Decent work and economic growth 2018-12-05T08:05:58Z 2018-12-05T08:05:58Z 2009/08/18 2018 Dissertation Tikam, M 2018, Posture control of a low-cost commercially available hexapod robot for uneven terrain locomotion, MEng Dissertation, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/67920> S2018 http://hdl.handle.net/2263/67920 en © 2018 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | Unrestricted UCTD Legged robots Hexapod robot Posture control Virtual model control Force control Uneven terrain locomotion Engineering, built environment and information technology theses SDG-09 SDG-09: Industry, innovation and infrastructure Engineering, built environment and information technology theses SDG-11 SDG-11: Sustainable cities and communities Engineering, built environment and information technology theses SDG-08 SDG-08: Decent work and economic growth Posture control of a low-cost commercially available hexapod robot for uneven terrain locomotion |
| title | Posture control of a low-cost commercially available hexapod robot for uneven terrain locomotion |
| title_full | Posture control of a low-cost commercially available hexapod robot for uneven terrain locomotion |
| title_fullStr | Posture control of a low-cost commercially available hexapod robot for uneven terrain locomotion |
| title_full_unstemmed | Posture control of a low-cost commercially available hexapod robot for uneven terrain locomotion |
| title_short | Posture control of a low-cost commercially available hexapod robot for uneven terrain locomotion |
| title_sort | posture control of a low cost commercially available hexapod robot for uneven terrain locomotion |
| topic | Unrestricted UCTD Legged robots Hexapod robot Posture control Virtual model control Force control Uneven terrain locomotion Engineering, built environment and information technology theses SDG-09 SDG-09: Industry, innovation and infrastructure Engineering, built environment and information technology theses SDG-11 SDG-11: Sustainable cities and communities Engineering, built environment and information technology theses SDG-08 SDG-08: Decent work and economic growth |
| url | http://hdl.handle.net/2263/67920 |