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Guidance, control, and motion planning for a hexapod robot moving over uneven terrain
Thesis (MEng)--Stellenbosch University, 2023.
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| Format: | Thesis |
| Language: | en_ZA en_ZA |
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Stellenbosch : Stellenbosch University
2023
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| _version_ | 1867613774469398528 |
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| access_status_str | Open Access |
| author | Erasmus, Sheldon |
| author2 | Engelbrecht, Japie |
| author_browse | Engelbrecht, Japie Erasmus, Sheldon |
| author_facet | Engelbrecht, Japie Erasmus, Sheldon |
| author_sort | Erasmus, Sheldon |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2023. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/127268 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA en_ZA |
| last_indexed | 2026-06-10T12:41:29.531Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/127268 Guidance, control, and motion planning for a hexapod robot moving over uneven terrain Erasmus, Sheldon Engelbrecht, Japie Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. Robots -- Control systems Servomechanisms Mathematical models Thesis (MEng)--Stellenbosch University, 2023. ENGLISH ABSTRACT: This thesis presents a novel hexapod guidance and control system that enables an autonomous hexapod robot to walk over uneven terrain while navigating waypoints and keeping its central body level. A physical hexapod robot has been designed and constructed to test the system. The design for the mechanical hardware of the physical hexapod is based on the work of Christopher et al., with modifications made to their design to accommodate larger servo motors. The electronic hardware and software have been developed from scratch. The hardware includes a NVIDIA Jetson Nano as the onboard computer, a Teensy microcontroller to control the servo actuators, a local positioning system, an inertial measurement unit, and an Intel RealSense depth camera. The main hexapod software has been implemented on the Jetson Nano using ROS to communicate between different parts of the software, including the Teensy that receives the paths send by the Jetson Nano, convert it to angle commands and then send it to the servo motors. A mathematical model of the hexapod robot has been obtained that can be used with a foot path to move the hexapod. The mathematical model consists of the kinematics of the hexapod’s legs and body. It uses the inverse kinematics of the legs to determine the joint angles required to move the feet to a specified position. The body kinematics is used to connect the different kinematics of the legs to a central position, allowing a position in the body coordinate system to be transformed to the coordinates of a specific leg. Leg motion planning algorithms, leg motion controllers, feedback controllers, guidance algorithms, and uneven terrain adaptation have all been developed, implemented, and tested. The leg motion planning algorithms have been based on those described in Christopher et al., and are used to generate trajectories between the start, mid, and end positions of the hexapod’s feet. The leg motion controllers uses the mathematical model to convert the planned foot trajectories into angle commands for the servomotors that actuate the hexapod’s legs. Feedback controllers have been developed to keep the hexapod at a reference tilt angle, a reference heading, and a reference in-track position. A guidance algorithm has been developed to guide the hexapod onto the ground track between waypoints by controlling the cross-track position error to zero. A uneven terrain adaptation algorithm has been developed that uses a depth camera to sense the terrain and adjust the leg motions accordingly. AFRIKAANSE OPSOMMING: Hierdie tesis beskryf ’n nuwe hexapod leiding- en beheerstelsel wat ’n outonome hexapodrobot in staat stel om oor ongelyke terrein te loop terwyl hy na wegpunte navigeer en sy sentrale liggaamsvlak gelyk hou. ’n Fisiese hexapod-robot is ontwerp en gebou om die stelsel te toets. Die ontwerp vir die meganiese hardeware van die fisiese hexapod is gebaseer op die werk van Christopher et al., met wysigings aan hul ontwerp om groter servo-motors toe te laat. Die elektroniese hardeware en sagteware is self ontwikkel. Die hardeware sluit ’n NVIDIA Jetson Nano as die aanboordrekenaar, ’n Teensy-mikrokontroleerder om die servo-aksies te beheer, ’n plaaslike posisioneringstelsel, ’n inertiële metings-eenheid en ’n Intel RealSense-dieptekamera in. ’n Wiskundige model van die hexapod-robot wat met ’n voetpad gebruik kan word om die hexapod te beweeg, is verkry. Die wiskundige model bestaan uit die kinematika van die hexapod se bene en liggaam. Dit gebruik die omgekeerde kinematika van die bene om die gewrigshoeke te bepaal wat benodig word om die voete na ’n bepaalde posisie te beweeg. Die liggaamkinematika word gebruik om die verskillende kinematika van die bene aan ’n sentrale posisie te koppel, wat ’n posisie in die liggaamskoördinaatstelsel na die koördinate van ’n spesifieke been kan omskep. Beenbewegings beplanningalgoritmes, beenbewegings beheerders, terugvoer beheerders, leiding algoritmes en ongelyke terrein aanpassing is almal ontwikkel, geïmplementeer en getoets. Die beenbewegings beplannings algoritmes is gebaseer op dié van Christopher et al., en word gebruik om trajektorieë tussen die begin-, middel- en eindposisies van die hexapod se voete te genereer. Die beenbewegings beheerders gebruik die wiskundige model om die beplande voet-trajektorieë om te skakel na hoekbevele vir die servo-motors wat die hexapod se bene aandryf. Terugvoer beheerders is ontwikkel om die hexapod by ’n verwysings-kantelhoek, ’n verwysings-kopligting en ’n verwysings-in-spoor posisie te hou. ’n Leidings algoritme is ontwikkel om die hexapod op die grondspoor tussen wegpunte te lei deur die kruis-spoor posisie fout tot nul te beheer. ’n Ongelyke terrein-aanpassings algoritme is ontwikkel wat ’n dieptekamera gebruik om die terrein waar te neem en die beenbewegings daarteenvolg aan te pas. Die leiding- en beheerstelsel is eers in ’n Gazebo-simulasie van die hexapod-robot geïmplementeer en geverifieer deur gebruik te maak van ROS voordat dit op die fisiese hexapod Masters 2023-03-03T12:03:38Z 2023-05-18T07:13:08Z 2023-03-03T12:03:38Z 2023-05-18T07:13:08Z 2023-03 Thesis http://hdl.handle.net/10019.1/127268 en_ZA en_ZA Stellenbosch University xvii, 169 pages : illustrations. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Robots -- Control systems Servomechanisms Mathematical models Erasmus, Sheldon Guidance, control, and motion planning for a hexapod robot moving over uneven terrain |
| title | Guidance, control, and motion planning for a hexapod robot moving over uneven terrain |
| title_full | Guidance, control, and motion planning for a hexapod robot moving over uneven terrain |
| title_fullStr | Guidance, control, and motion planning for a hexapod robot moving over uneven terrain |
| title_full_unstemmed | Guidance, control, and motion planning for a hexapod robot moving over uneven terrain |
| title_short | Guidance, control, and motion planning for a hexapod robot moving over uneven terrain |
| title_sort | guidance control and motion planning for a hexapod robot moving over uneven terrain |
| topic | Robots -- Control systems Servomechanisms Mathematical models |
| url | http://hdl.handle.net/10019.1/127268 |
| work_keys_str_mv | AT erasmussheldon guidancecontrolandmotionplanningforahexapodrobotmovingoveruneventerrain |