Modeling and Direct Adaptive Control of a Flexible- Joint Manipulator

Abstract

This paper addresses the problem of adaptive trajectory control of space manipulators that exhibit elastic vibrations in their joints and that are subject to parametric uncertainties and modeling errors. First, it presents a comprehensive study of rigid and linear flexible-joint stiffness models, to propose a dynamic formulation that includes nonlinear effects such as soft-windup and time-varying joint stiffness. Second, it develops an adaptive composite control scheme for tracking the end effector of a two-link flexible-joint manipulator. The control scheme consists of a direct model reference adaptive system designed to stabilize the rigid dynamics and a linear correction term to improve damping of vibrations at the joints. Numerical simulations compare the performance of the adaptive controller with its nonadaptive version in the context of a 12:6 12:6 m square trajectory tracking. Results obtained with the adaptive control strategy show an increased robustness to modeling errors and uncertainties in joint stiffness coefficients, and greatly improved tracking performance, compared with the nonadaptive strategy.

2D Microgravity Test-Bed for the Validation of Space Robot Control Algorithms

“…In extreme situations, a space robot can be controlled in an open loop, basing only on an initial state and an accurate mathematical model. However, taking into consideration that capturing with a robotic arm is a highly dynamic and risky manoeuvre, it is very important to develop a closed loop control system with signals from specialized sensors [1], [10], [18], [34], [42].…”

Higher Performance Adaptive Control of a Flexible Joint Robot Manipulators

“…Adaptive trajectory control scheme consists of a direct (MRAS) is presented [18] to improve damping of vibration at the joints. An adaptive fussy output feedback approach is proposed [19] to compensate for nonlinear dynamics while only requiring the measurement of link position.…”

Novel Adaptive PID Control of Flexible Joint Robot Manipulator withBounded Disturbances

“…Adaptive trajectory control scheme consists of a direct (MRAS) is presented [30] to improve damping of vibration at the joints. An adaptive fussy output feedback approach is proposed [31] to compensate for nonlinear dynamics while only requiring the measurement of link position.…”