Design and Analysis of Controller for a Robotic Arm Manipulator via State Space Approach

The purpose of this study is to analyze and design a controller for robotic arm manipulator via state space approach. The dynamic of the system is modeled in state space representation as it provides a convenient and systematic way to model and analyze any systems

Design and Analysis of Controller for a Robotic Arm Manipulator via State Space Approach

The purpose of this study is to analyze and design a controller for robotic arm manipulator via state space approach. The dynamic of the system is modeled in state space representation as it provides a convenient and systematic way to model and analyze any systems

An acceleration-based state observer for robot manipulators with elastic joints

Robots that use cycloidal gears, belts, or long shafts for transmitting motion from the motors to the driven rigid links display visco-elastic phenomena that can be assumed to be concentrated at the joints. For the design of advanced, possibly nonlinear, trajectory tracking control laws that are able to fully counteract the vibrations due to joint elasticity, full state feedback is needed. However, no robot with elastic joints has sensors available for its whole state, i.e., for measuring positions and velocities of both motors and links. Several nonlinear observers have been proposed in the past, assuming different reduced sets of measurements. We introduce here a new observer which uses only motor position sensing, together with accelerometers suitably mounted on the links of the robot arm. Its main advantage is that the error dynamics on the estimated state is independent from the dynamic parameters of the robot links, and can be tuned with standard decentralized linear techniques (locally to each joint). We present an experimental validation of this observer for the three base joints of a KUKA KR15/2 industrial robot and illustrate the control use of the obtained results

An Acceleration-based State Observer for Robot Manipulators with Elastic Joints

Abstract — Robots that use cycloidal gears, belts, or long shafts for transmitting motion from the motors to the driven rigid links display visco-elastic phenomena that can be assumed to be concentrated at the joints. For the design of advanced, possibly nonlinear, trajectory tracking control laws that are able to fully counteract the vibrations due to joint elasticity, full state feedback is needed. However, no robot with elastic joints has sensors available for its whole state, i.e., for measuring positions and velocities of both motors and links. Several nonlinear observers have been proposed in the past, assuming different reduced sets of measurements. We introduce here a new observer which uses only motor position sensing, together with accelerometers suitably mounted on the links of the robot arm. Its main advantage is that the error dynamics on the estimated state is independent from the dynamic parameters of the robot links, and can be tuned with standard decentralized linear techniques (locally to each joint). We present an experimental validation of this observer for the three base joints of a KUKA KR15/2 industrial robot and illustrate the control use of the obtained results. I

Controle de força indireto para manipuladores com transmissões flexíveis empregados em tarefas de esmerilhamento

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Elétrica.A flexibilidade ´e um efeito presente em muitos dos rob#os industriais provocando erros de posicionamento, aumento do tempo de estabiliza¸c#ao e at´e instabilidade. Neste trabalho, o problema do controle de for¸ca em rob#os manipuladores com transmiss#oes flex´ýveis (MTF#s) empregados em tarefas de esmerilhamento ´e estudado. Duas estrat´egias de controle de for¸ca indireto para manipuladores r´ýgidos s#ao estendidas para manipuladores com transmiss#oes flex´ýveis: o controle de rigidez e o controle de imped#ancia. Um modelo de for¸cas para a tarefa de esmerilhamento ´e proposto para o estudo da estabilidade e desempenho de ambas as estrat´egias. Buscando a implementa¸c#ao pr´atica destes controladores, dois observadores de estado - um observador de estados baseado na acelera¸c#ao e outro baseado em torques de dist´urbio - s#ao apresentados para estimar as vari´aveis dos elos e das for¸cas de contato com o objetivo de evitar a necessidade da instrumenta¸c#ao completa do manipulador. O desempenho das estrat´egias de controle e dos observadores ´e avaliado frente a tarefa de esmerilhamento pela an´alise dos resultados obtidos em simula¸c#ao. Esta disserta¸c#ao tamb´em apresenta o software de simula¸c#ao desenvolvido para facilitar a obten¸c#ao de resultados, o que engloba todo o conte´udo estudado. Flexibility is an effect present in many industrial robots causing positioning errors, increasing the stabilization time and even instability. In this paper, the force control problem of robot manipulators with flexible transmissions employed in milling tasks is studied. Two strategies of indirect force control for rigid manipulators are extended to manipulators with flexible transmissions: the compliance control and the impedance control. A model of forces for milling tasks is proposed to study the stability and performance of both strategies. Seeking a practical implementation of these controllers, two state observers - an state observer based on acceleration and another based on disturbance torques - are presented to estimate the variables of the links and the forces of contact with goal of avoid the need for full instrumentation of the manipulator. The performance of the control strategies and observers is evaluated against the milling task by analysis of results obtained in simulation. This document also presents the program of simulation developed and used, throughout this research, to facilitate the achievement of results. This software includes all the content studied