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A feasibility study of trajectory optimisation on a low-cost legged platform with open loop control.
Thesis (MEng)--Stellenbosch University, 2024.
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| Format: | Thesis |
| Language: | en_ZA en_ZA |
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Stellenbosch : Stellenbosch University
2024
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| _version_ | 1867614058668097536 |
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| access_status_str | Open Access |
| author | Coetzer, Margarethe |
| author2 | Fisher, Callen |
| author_browse | Coetzer, Margarethe Fisher, Callen |
| author_facet | Fisher, Callen Coetzer, Margarethe |
| author_sort | Coetzer, Margarethe |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2024. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/130301 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA en_ZA |
| last_indexed | 2026-06-10T12:45:58.010Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2024 |
| publishDateRange | 2024 |
| publishDateSort | 2024 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/130301 A feasibility study of trajectory optimisation on a low-cost legged platform with open loop control. Coetzer, Margarethe Fisher, Callen Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. Mobile robots Trajectory optimization Bipedalism Ring networks (Computer networks) UCTD Thesis (MEng)--Stellenbosch University, 2024. ENGLISH ABSTRACT: The main aim of legged robots are to achieve the mobility and versatility of movements exhibited by humans and animals effortlessly traversing various terrains. Recent advances in legged robots have been able to create mobile robots that can traverse rough terrain, perform plant inspections and even do parkour maneuvers. Legged robotics is still widely considered as an unsolved problem due to the complexity and cost of these systems. Previously dramatic model simplifications were required to produce trajectory optimisation gaits; however recent advances in computational power has enabled the use of more accurate trajectory optimisation models. This thesis assesses the feasibility of implementing a trajectory optimisation gait on a low-cost legged platform without the use of additional environmental feedback sensors. A free moving four-legged robot was designed, with legs that have two degrees of freedom each. The platform was built using mainly commercial components and was actuated using servo motors. The trajectory optimisation was initially performed on a 2D model of the quadruped. Through experimentation it was concluded that in order for the simplified 2D trajectory model to generate plausible platform gaits, a minimum foot clearance height had to be enforced during the flight stage of each step. This created gaits that were plausible for implementation on the platform. The platform was able to realise a greater travel distance for greater clearance heights. For the greatest foot clearance height of 2 cm implemented, the platform was able to realise an average of 58% of the expected travel distance. It was theorised that a 3D model would yield better results, because the trajectory would be able to consider the body width, roll and yaw. A 3D trajectory model was consequently created that also enforced a minimum clearance height. The platform results with clearance heights of 1.0 cm and less yielded unreliable gaits. However, for clearance heights of 1.5 cm and above the gaits yielded fairly consistent results. At 1.5 and 2 cm, the platform was able to respectively realise 66% and 82% of the expected travel distance. With a realised travel distance of 82%, it is deemed feasible to implement open-loop trajectory optimisation gaits on a low-cost legged platform. AFRIKAANSE OPSOMMING: Die primêre doelwit van gebeende robotte is om met soortgelyke gemak van mense en diere oor verskillende terreine the beweeg. Onlangse vooruitgang in gebeende robotte het mobiele robotte geskep wat oor rowwe terrein kan beweeg, fabriek inspeksies kan uitvoer en selfs kan selfs ’n paar toertjies doen. Been-robotika word steeds as ’n onopgeloste probleem beskou, aangesien die sisteme baie kompleks en duur is. Voorheen was dramatiese modelvereenvoudigings nodig om trajek-optimeringsgange te produseer, maar onlangse vooruitgang in rekenkrag het die gebruik van meer akkurate trajek-optimeringsmodelle moontlik gemaak. In hierdie tesis is die haalbaarheid van die implementering van trajek-optimering-gegenereerde gange op ’n laekoste-beenplatform sonder die gebruik van addisionele omgewingsterugvoersensors geassesseer. ’n Vrybewegende viervoetige-robot is ontwerp, met bene wat elk twee vryheidsgrade het. Die platform is ontwerp om hoofsaaklik van kommersiële komponente gebruik te maak en is aangedryf met behulp van servo-motors. Aanvanklik is die trajek-optimering op ’n 2D-model van die viervoet uitgevoer. Deur eksperimentasie is daar tot die gevolgtrekking gekom dat, vir die vereenvoudigde 2D-trajekmodel gange om op die platform haalbaar te wees, ’n minimum traphoogte beperking bygevoeg moes word. Dit het gange geskep wat gepas was vir implementering op die platform. Die platform kon meer van die verwagte reisafstand aflê vir groter traphoogte waardes. Vir die maksimum traphoogte van 2 cm wat geïmplementeer is, kon die platform ’n gemiddeld van 58% van die verwagte reisafstand realiseer. Daarna is geteoretiseer dat ’n 3D-model beter resultate sal lewer, omdat dit die platform breedte en beweging om die x- en z axis ook in ag kan neem. Gevolglik is ’n 3D-trajekmodel geskep, ook met die minimum traphoogte beperking afgedwing. Met traphoogtes van 1.0 cm en kleiner was resultate opgelewer wat baie verskil het en dit gevolglik onvoorspelbaar gemaak het. Vir minimum traphoogtes van 1.5 cm en meer het die platform egter redelik konsekwente resultate opgelewer. Vir traphoogtes van 1,5 en 2 cm kon die platform onderskeidelik 66% en 82% van die verwagte reisafstand realiseer. Die resultate bewys dat dit moontlik is om trajekoptimeringsgange sonder addisionele beheer mekanismes op ’n laekoste-beenplatform te implementeer, gegewe dat die model en beperkings voldoende gedefinieer is. Masters 2024-02-29T07:15:56Z 2024-04-26T12:37:41Z 2024-02-29T07:15:56Z 2024-04-26T12:37:41Z 2024-03 Thesis https://scholar.sun.ac.za/handle/10019.1/130301 en_ZA en_ZA Stellenbosch University xvii, 146 pages : illustrations. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Mobile robots Trajectory optimization Bipedalism Ring networks (Computer networks) UCTD Coetzer, Margarethe A feasibility study of trajectory optimisation on a low-cost legged platform with open loop control. |
| title | A feasibility study of trajectory optimisation on a low-cost legged platform with open loop control. |
| title_full | A feasibility study of trajectory optimisation on a low-cost legged platform with open loop control. |
| title_fullStr | A feasibility study of trajectory optimisation on a low-cost legged platform with open loop control. |
| title_full_unstemmed | A feasibility study of trajectory optimisation on a low-cost legged platform with open loop control. |
| title_short | A feasibility study of trajectory optimisation on a low-cost legged platform with open loop control. |
| title_sort | feasibility study of trajectory optimisation on a low cost legged platform with open loop control |
| topic | Mobile robots Trajectory optimization Bipedalism Ring networks (Computer networks) UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/130301 |
| work_keys_str_mv | AT coetzermargarethe afeasibilitystudyoftrajectoryoptimisationonalowcostleggedplatformwithopenloopcontrol AT coetzermargarethe feasibilitystudyoftrajectoryoptimisationonalowcostleggedplatformwithopenloopcontrol |