Title Adaptivno upravljanje gibanjem četveronožnog robota korištenjem promjenjive podatnosti rotirajućih spiralnih stopala Title (english) Adaptive control of quadruped robot locomotion through variable compliance of revolute spirar feet Author Alan Mutka Mentor Zdenko Kovačić (mentor)Committee member Zdenko Kovačić (član povjerenstva)Granter University of Zagreb Defense date and country 2015, Croatia Scientific / art field, TECHNICAL SCIENCES Universal decimal classificationUDC ) 621.3 - Electrical engineering Abstract Područje istraživanja doktorske disertacije vezano je za projektiranje i integraciju sustava upravljanja četveronožnih robotskih hodača. Istraživanje je podijeljeno u tri nezavisne cjeline (adaptivna podatnost, kinematika te generiranje sekvenci gibanja) koje se u konačnici integriraju s ciljem dobivanja što prirodnijeg i energetski učinkovitijeg robotskog gibanja. Uloga adaptivne podatnosti odnosno adaptacije elastičnosti noge s obzirom na podlogu i frekvenciju kretanja važna je za postizanje
... More energetski optimalnog kretanja. Osim sposobnosti adaptacije podatnosti, javlja se potreba i za detekcijom promjene krutosti podloge s ciljem zadržavanja stabilnosti kretanja. U disertaciji je prikazano oblikovanje podatnog robotskog stopala koje ima sposobnost promjene pasivne podatnosti te detekcije elastičnosti podloge po kojoj se kreće. Za postizanje modularnog i robusnog sustava upravljanja važno je odvojiti kinematiku jedne noge od kinematike centra tijela. Rješavanje inverznog kinematičkog problema za upravljanje pozicijom i orijentacijom stopala noge u odnosu prema koordinatnom sustavu kuka ili baze robota izvedeno je analitičkim putem zbog malog broja stupnjeva slobode gibanja. S druge strane, upravljanje pozicijom i orijentacijom centra tijela robota riješeno je korištenjem matrice Jakobijana. Prednost korištenja matrice Jakobijana je u mogućnosti iskorištavanja viška stupnjeva slobode gibanja upravljanjem preko nul-prostora matrice sustava. Ovaj pristup omogućuje da se istovremeno, osim pozicijom i orijentacijom centra tijela, može upravljati i nekim dodatnim uvjetom, kao što je raspored centra mase i slično. Generiranje cikličkih sekvenci (hod, kas, galop...) te acikličkih sekvenci gibanja (lijeganje, ustajanje, sjedanje...) izvedeno je u lokalnom koordinatnom sustavu svake noge korištenjem trajektorija koje opisuju kretanje vrha stopala. Sinkronizacija četiriju nogu koja je ključna za postizanje određenog tipa gibanja izvedena je korištenjem automata stanja. Predstavljeni upravljački algoritam ima mogućnost izvođenja cikličkih i acikličkih trajektorija, kontrolirane promjene sekvenci gibanja te omogućuje integraciju sa spomenutom kinematikom centra tijela. Eksperimentalna validacija predstavljenog upravljačkog sustava izvedena je na sveukupno četiri istraživačke platforme: tri varijante četveronožnog hodača pogonjenog električkim motorima (Dynarobin 1, 2 i 3) te na četverokračnom mobilnom robotu s pogonskim gusjenicama (VIV). Eksperimenti su provedeni unutar virtualnog okruženja te na realnim sustavima. Less Abstract (english) Research presented in the dissertation is related to the design and integration of a control system for quadruped robot locomotion. The research is divided into three independent parts (adaptive compliance, kinematics and motion trajectory generation), which are integrated in one system with a main goal of achieving more natural and energy efficient quadruped robot locomotion. Adaptation of leg compliance with respect to the changes in ground stiffness and stride frequency proved to be
... More essential in achieving energy optimal locomotion. To facilitate both compliance adaptation and maintaining the stability of locomotion, a control system needs to be able to detect the changes in the stiffness. This dissertation showcases a novel mechanical design of a compliant robot leg with both active and variable passive compliance. Additionally, the design allows for the detection of the changes in ground stiffness by measuring contact time from a feedback signal from the flex sensors mounted on the spiral feet. In order to achieve modular and robust quadruped robot control system it is important to approach to the single leg kinematics and the whole body kinematics separately. The single leg inverse kinematics problem in relation to hip or central body coordinate system is calculated analytically due to a limited number of degrees of freedom. On the other hand, the whole body position and orientation control in relation to a world coordinate system is performed by using the Jacobian matrix. Jacobian pseudoinverse with local null-space optimization enables the control system to utilize the redundancy of the robot and allows for definition of various optimization criteria (e.g. minimization of kinetic energy) or to aid in some additional task achievement (e.g. mass distribution control). Dynamic (cyclic) trajectory (walk, trot, gallop, ...) and static (acyclic) trajectory (getting up, lying down, sitting down...) motion sequence generation is performed in a local leg coordinate system by using the trajectories describing the motion of the foot. In order to obtain specific gait motion, all four leg trajectories are synchronized through a state machine. The presented control algorithm has ability to perform dynamic and static trajectories, provides controllable changes of motion sequences and ensures integration with the mentioned whole body kinematics. The experimental validation of the presented control system is carried out on four research platforms: three versions of electrically driven quadruped platforms, and the four-flipper tracks-driven mobile robot. The experiments have been performed in virtual and real environments. The first chapter gives an introduction into the field and research goals. The second chapter provides an overview of the existing mechanical robot leg designs with passive, active and hybrid compliance ability. A novel design of a quadruped robot is presented. Proposed novel legs have feet in the form of a spiral spring attached to the rotary shaft of the ankle. The fact that the spiral spring can rotate and change the contact angle with the ground extends the variable passive property to the leg in a whole and thus enables direct stiffness control during robot motion. Foot spring stiffness and damping are experimentally identified. The foot contact angle adaptation algorithm, based on a contact time feedback measurement by a flex sensor, is presented and tested on a single leg experimental platform. Chapter 3 gives an overview of the current state of the research in the area of velocity transform theory and introduces general central body kinematics model. The central body position and orientation control is performed by using the Jacobian matrix. Jacobian pseudoinverse with local null-space optimization uses robot's redundancy to define various optimization criteria (minimisation kinetic energy) or to aid in some additional task achievement (mass distribution control). The presented general central body kinematics model is implemented and tested on several quadruped platforms (Dynarobin v. 1, 2, and 3) and on the mobile robot for exploration and inspection (VIV). Chapter 4 defines general tasks for control system in terms of motion trajectory generation, as for dynamics trajectories (walk, trot, gallop, ...) with controllable gait switching ability, so for static trajectories (getting up, lying down, sitting down...). Two existing trajectory generation concepts are presented: central pattern generator based on coupled oscillators, and SIMBICON which is based on state machines. Improved trajectory generation concept based on a state machine with integrated central body kinematics is presented. The foot trajectories for all types of four-legged gaits are described as cyclic trajectories divided into three segments: propel, push and adjust. The presented control system is validated inside virtual environment. Chapter 5 deals with the presented control system experimentally validated on a real quadruped robot, version Dynarobin \#3. The experiments confirm that the presented control system can generate dynamic and static quadruped motion trajectories with the ability to simultaneously control the position and orientation of the body. This chapter also gives concluding remarks and provides guidelines for future work regarding energy efficient quadruped locomotion, robot stiffness adaptation to stiffness variations of natural uneven terrains, etc. Less Keywords
četveronožno gibanje robota
pasivna promjenjiva podatnost
adaptivno upravljanje podatnosti
kinematika centra tijela
trodjelna ciklička trajektorija
Keywords (english)
quadruped locomotion
passive variable compliance
adaptive compliance control
central body kinematics
three segmented cyclic trajectory
Language croatian URN:NBN urn:nbn:hr:168:885071 Study programme Title: Electrical Engineering and Computing Type of resource Text Extent 189 str. ; 30 cm. File origin Born digital Access conditions Closed access Terms of use Created on 2019-04-16 13:33:14
