Omnidirectional Control of the Hexapod Robot TigerBug

TigerBug is a six legged, hexapod robot built and designed by students in the Rochester Institute of Technology\u27s (RIT) Multi Agent Bio-Robotics Laboratory (MABL). TigerBug is comprised of 18 servo motors, 3 degrees of freedom (DOF) per leg, supported by carbon fiber wrapped foam legs placed in a circular pattern around its hexagon shaped body. In order to control such a complex system, much research has been done in the field of kinematics. There exist two derivations of kinematic solutions, forward and inverse. The forward kinematic (FK) solution tends to be much simpler than its inverse kinematic (IK) counterpart. There has been many methods developed to quickly, and efficiently solve the IK in order to control the position and orientation of a robot. This thesis details the process of developing the IK solution and two gait algorithms for TigerBug. The IK solution was developed by first solving for the FK solution of TigerBug using Denavit-Hartenberg (DH) Parameters. After the FK solution was solved, differentials were applied to each equation in order to solve for the IK solution. Once the IK solution was tested, a fixed gait algorithm was developed in order to understand basic motion control of hexapod locomotion. Once the fixed gait was implemented successfully a rule-based free gait algorithm was developed. The rule-based free gait was accomplished using the rule set governed by restrictiveness to determine when leg state transitions were to occur, as described in the literature. Once implemented, the different combinations of gait parameters were tested for quickness of convergence and efficiency to determine the most optimal set of walking parameters for TigerBug

Integrative Biomimetics of Autonomous Hexapedal Locomotion

Dürr V, Arena PP, Cruse H, et al. Integrative Biomimetics of Autonomous Hexapedal Locomotion. Frontiers in Neurorobotics. 2019;13: 88.Despite substantial advances in many different fields of neurorobotics in general, and biomimetic robots in particular, a key challenge is the integration of concepts: to collate and combine research on disparate and conceptually disjunct research areas in the neurosciences and engineering sciences. We claim that the development of suitable robotic integration platforms is of particular relevance to make such integration of concepts work in practice. Here, we provide an example for a hexapod robotic integration platform for autonomous locomotion. In a sequence of six focus sections dealing with aspects of intelligent, embodied motor control in insects and multipedal robots—ranging from compliant actuation, distributed proprioception and control of multiple legs, the formation of internal representations to the use of an internal body model—we introduce the walking robot HECTOR as a research platform for integrative biomimetics of hexapedal locomotion. Owing to its 18 highly sensorized, compliant actuators, light-weight exoskeleton, distributed and expandable hardware architecture, and an appropriate dynamic simulation framework, HECTOR offers many opportunities to integrate research effort across biomimetics research on actuation, sensory-motor feedback, inter-leg coordination, and cognitive abilities such as motion planning and learning of its own body size

Investigation of energy efficiency of hexapod robot locomotion

Disertacijoje nagrinėjamos vaikščiojančių robotų energijos sąnaudų problemos jiems judant lygiu ir nelygiu paviršiumi. Pagrindinis tyrimo objektas yra vaikščiojančio roboto valdymo, aplinkos atpažinimo bei kliūčių išvengimo žinomoje aplinkoje metodas. Energijos sąnaudų minimizavimas leistų praplėsti vaikščiojančių robotų pritaikymą ir veikimo laiką. Pagrindinis darbo tikslas – sukurti energijos sąnaudų minimizavimo metodus vaikščiojantiems robotams ir sukurti aplinkos atpažinimo ir klasifikavimo metodus bei ištirti šešiakojo roboto energijos sąnaudas jiems judant žinomoje aplinkoje. Šie metodai gali būti taikomi vaikščiojantiems daugiakojams robotams. Darbe sprendžiami šie uždaviniai: šešiakojo roboto eisenos parinkimas atsižvelgiant į energijos sąnaudas, paviršiaus kliūčių aptikimo ir perlipimo metodų sudarymas ir jų efektyvumo palyginimas. Taip pat sprendžiami uždaviniai, kurie siejasi su pėdų trajektorijos generavimo metodo kūrimu bei kliūčių dydžio ir tankio įtaka roboto energijos sąnaudoms. Disertaciją sudaro įvadas, trys skyriai, bendrosios išvados, naudotos literatūros ir autoriaus publikacijų disertacijos tema sąrašai. Įvade aptariama tiriamoji problema, darbo aktualumas, aprašomas tyrimų objektas, formuluojamas darbo tikslas bei uždaviniai, aprašoma tyrimų metodika, darbo mokslinis naujumas, darbo rezultatų praktinė reikšmė, ginamieji teiginiai. Įvado pabaigoje pristatomos disertacijos tema autoriaus paskelbtos publikacijos ir pranešimai konferencijose bei disertacijos struktūra. Pirmasis skyrius skirtas literatūros apžvalgai. Jame pateikta mobiliųjų robotų energetinio efektyvumo bei energijos sąnaudų matavimo, skaičiavimo ir optimizavimo metodų analizė. Antrajame skyriuje pateiktas energetiškai efektyvaus judėjimo metodikos sudarymas vaikščiojantiems robotams. Šiame skyriuje pateiktas šešiakojo roboto matematinio ir fizinio modelių sudarymas, nelygaus paviršiaus klasifikavimo modelio sudarymas bei taktilinio kliūčių aptikimo bei perlipimo metodų sudarymas. Skyriaus gale pateikiamos išvados. Trečiajame skyriuje tiriamos energijos sąnaudų priklausomybės nuo roboto eisenos bei judėjimo parametrų, kliūčių aptikimo ir perlipimo tikslumas priklausomai nuo kliūčių skaičiaus roboto kelyje, taip pat kliūčių dydžio ir tankio įtaka roboto energijos sąnaudoms. Disertacijos tema paskelbti 9 straipsniai: keturi – Clarivate Analytics Web of Science duomenų bazės leidiniuose, turinčiuose citavimo rodiklį, trys – Clarivate Analytics Web of Science duomenų bazės „Conference Proceedings“ leidiniuose ir du – kituose recenzuojamuose mokslo leidiniuose. Disertacijos tema perskaityti 7 pranešimai konferencijose Lietuvoje bei kitose šalyse

Decentralised Compliant Control for Hexapod Robots: A Stick Insect Based Walking Model

Institute of Perception, Action and BehaviourThis thesis aims to transfer knowledge from insect biology into a hexapod walking robot. The similarity of the robot model to the biological target allows the testing of hypotheses regarding control and behavioural strategies in the insect. Therefore, this thesis supports biorobotic research by demonstrating that robotic implementations are improved by using biological strategies and these models can be used to understand biological systems. Specifically, this thesis addresses two central problems in hexapod walking control: the single leg control mechanism and its control variables; and the different roles of the front, middle and hind legs that allow a decentralised architecture to co-ordinate complex behavioural tasks. To investigate these problems, behavioural studies on insect curve walking were combined with quantitative simulations. Behavioural experiments were designed to explore the control of turns of freely walking stick insects, Carausius morosus, toward a visual target. A program for insect tracking and kinematic analysis of observed motion was developed. The results demonstrate that the front legs are responsible for most of the body trajectory. Nonetheless, to replicate insect walking behaviour it is necessary for all legs to contribute with specific roles. Additionally, statistics on leg stepping show that middle and hind legs continuously influence each other. This cannot be explained by previous models that heavily depend on positive feedback controllers. After careful analysis, it was found that the hind legs could actively rotate the body while the middle legs move to the inside of the curve, tangentially to the body axis. The single leg controller is known to be independent from other legs but still capable of mechanical synchronisation. To explain this behaviour positive feedback controllers have been proposed. This mechanism works for the closed kinematic chain problem, but has complications when implemented in a dynamic model. Furthermore, neurophysiological data indicate that legs always respond to disturbances as a negative feedback controller. Additional experimental data presented herein indicates that legs continuously oppose forces created by other legs. This thesis proposes a model that has a velocity positive feedback control modulated via a subordination variable in cascade with a position negative feedback mechanism as the core controller. This allows legs to oppose external and internal forces without compromising inter-leg collaboration for walking. The single leg controller is implemented using a distributed artificial neural network. This network was trained with a wider range of movement to that so far found in the simulation model. The controller implemented with a plausible biologica