3D turning analysis of a Bipedal Robot

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dc.contributor.advisorFisher, Callenen_ZA
dc.contributor.authorPretorius, Deanen_ZA
dc.contributor.otherStellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.en_ZA
dc.date.accessioned2022-02-23T07:56:59Z
dc.date.accessioned2022-04-29T09:26:27Z
dc.date.available2022-02-23T07:56:59Z
dc.date.available2022-04-29T09:26:27Z
dc.date.issued2022-04
dc.descriptionThesis (MEng)--Stellenbosch University, 2022.en_ZA
dc.description.abstractENGLISH ABSTRACT: There is stark contrast between the abilities of legged locomotion found in nature, and locomotion found in lab environments. This performance gap is indicative of a large knowledge gap. Roboticists are required to bridge these gaps to truly invite robots to detach from their support rigs, and actuate within the real world. In this thesis, non-planar contact and discontinuous locomotive dynamics were modeled as a trajectory optimization problem. Consequently, this made understanding the complexities of legged locomotion more tractable. Understanding, and being able to leverage, contact is crucial to successful legged locomotion. Therefore, a comprehensive investigation was conducted into non-planar contact dynamics using a monopod robot. Here, methods of modeling the Coulomb friction cone in contact implicit trajectory optimization were implemented. Literature suggests replacing the friction cone with a polyhedral approximation thereof. However, this method is known to underestimate the resultant friction in non-planar environments. This thesis presents a novel method of modeling the 3D friction cone and compares it to an implementation of the polyhedral approximation. Results from this comparison show that the novel method was significantly more computationally efficient than the polyhedral approximation, without underestimating the friction cone. Dynamic bipedal locomotion remains a struggle for most robotic platforms. Robotics literature provides few examples of robots achieving agile, dynamic locomotion. Therefore, trajectories realizing non-planar dynamic bipedal motion were generated. Experiments were conducted into acceleration, steady-state, deceleration, and rapid turning off the sagittal plane. Optimal trajectories displayed the robot walking at speeds resulting in a Froude number less than 0.5, and running at speeds resulting in a higher Froude number. This is consistent with dynamic gaits found in nature. A sliding-mass velocity profile emerged when conducting long-time-horizon trajectories where the robot accelerated from a rest position and decelerated back to rest after completing multiple steps in a periodic steady-state gait. Additionally, when turning off the sagittal plane, slip occurred at least 93.32% of the duration of contact, and turn overshoot is present in all turn trajectories.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Daar is skerp kontras tussen die vermoëns van voortbeweging wat in die natuur voorkom, en di`e wat in laboratoriumomgewings voorkom. Hierdie prestasiegaping is aanduidend van ’n groot kennisgaping. Robotiste is verwag om hierdie gapings te oorbrug om robotte uit van hul ondersteuningplatforms uit te kom en in die werklike wˆereld te aandryf. In hierdie tesis word 3D kontak en diskontinue lokomotiefdinamika gemodelleer as ’n trajekoptime ringsprobleem. Gevolglik maak dit die verstandhouding van robotik gebeendebeweging makliker. Die verstaan van kontak, en hoe om dit te gebruik, is noodsaaklik vir suksesvolle voortbeweging. Daarom is ’n omvattende ondersoek uitgevoer, met behulp van ’n monopod robot, om kontakdinamika beter te verstaan. Hier word metodes van modellering van die Coulomb wrywings-keel in kontak-implisiete-trajek-optimering ge¨ımplementeer. Literatuur stel voor dat die wrywingskegel vervang word met ’n veelvlakkige benadering daarvan. Dit is bekend dat hierdie metode die gevolglike wrywing in 3D omgewings onderskat. Hierdie tesis bied ’n nuwe metode om die 3D-wrywingskegel te modelleer, en vergelyk dit met ’n implementering van die veelvlakkige benadering daarvan. Uitslae van hierdie vergelyking toon dat die nuwe metode meer berekeningsdoeltreffend was as die veelvlakkige benadering, sonder om die wrywingskegel te onderskat. Dinamiese tweevoetige voortbeweging bly ’n stryd vir die meeste robotplatforms. Robotikaliteratuur verskaf min voorbeelde van robotte wat dinamiese voortbeweging bereik. Daarom is trajekte gegenereer wat 3D dinamika van tweevoetbeweging realiseer. Eksperimente word uitgevoer na accelerasie, bestendige toestand, verlangsaming en draaie van die sagittale vlak af. Optimale trajekte het die robot laat stap teen ’n spoed wat ’n Froude-getal minder as 0.5 laat kom, en hardloop teen spoed wat ’n ho¨er Froude-getal gehad het. Dit stem ooreens met dinamiese voetvalpatrone wat in die natuur voorkom. ’n Glymassa-spoedprofiel het voor gekom toe die lang-tyd-horison trajekte uitgevoer word: waar die robot van ’n rusposisie versnel het en terug versnel is na rus nadat hy verskeie stappe in periodieke bestendige-toestand voltooi het. Wanneer die robot van die sagittale vlak afdraai, gly hy ten minste 93.32% van die tyd wat kontak plaasgevind, en beurtoorskiet is teenwoordig in alle draaie.af_ZA
dc.description.versionMastersen_ZA
dc.format.extent104 pagesen_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/124686
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subject3D turning analysisen_ZA
dc.subjectUCTDen_ZA
dc.subjectBipedal roboten_ZA
dc.subjectTrajectory optimizationen_ZA
dc.subjectBipedal locomotionen_ZA
dc.title3D turning analysis of a Bipedal Roboten_ZA
dc.typeThesisen_ZA
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