Model-based PID control of constrained robot in a dynamic environment with uncertainty

This paper investigates a model-based method for robot manipulator control by describing the kinematics and dynamics of constrained robot when contacting a dynamic environment. Parameters which concern kinematic constraints of robot end effector, dynamic interactions and uncertainty of environment are represented from the environment side. By using Lagrangian formula, the whole dynamic expressions of the robot-environment system can be derived by the variables representing the joint angles. This modeling method is suitable for hybrid control laws to fulfil the manipulation task. The simulation results obtained from PID regulators are presented. Those results suggest that in practice, fixed PID parameters may not perform well because of the strong nonlinearity of the system and this will lead to further modified PID method such as a fuzzy logic self-tuning PID controller to achieve the time-varying tracking control of the robot manipulator.