Robot Manipulator Redundancy Resolution

Chapter 14QP Based Encoder Feedback Control

14.1 Introduction

Given they have more DOF than required to perform a given end-effector primary task, redundant robot manipulators can achieve subtasks such as obstacle avoidance [87, 227], fault tolerance [228], repetitive motion planning [128, 229], joint limits, and singularity avoidance [230–232]. Existing optimal control methods for path planning and control of robot manipulators [233] can be roughly categorized into two types: First, optimal control methods that can handle each robot link separately without regard to robot dynamics by computing setpoints for low-level (e.g., position- or velocity-level) single-input single-output controllers [228, 234]; Second, optimal control methods that can handle the robot directly by considering robot dynamics and computing motor torques [235–237] for high-level controllers, specifically, torque-level controllers. The former methods pertain to the description of motion (position, velocity, acceleration, etc.). These methods can perform well if the desired motion is not too fast and does not require large acceleration [238]. The latter methods are related to the explanation of motion in terms of forces and torques and are applicable to numerous practical manipulators. The level at which path planning and control is performed may depend on the type of robot controller [239]. For example, if joints are driven by position- or velocity-controlled servo motors, then a path planning and control ...