Adaptive tracking control of on-line path planners: velocity fields and navigation functions

Traditionally, robot control research has focused on the position tracking problem where the objective is to force the robot´s end-effector to follow an a priori known desired time dependent trajectory. Motivated by task objectives that are more effectively described by on-line, state-dependent trajectories, two adaptive tracking controllers are developed in this paper that accommodate on-line path planning objectives. An example adaptive controller is first modified to achieve velocity field tracking in the presence of parametric uncertainty in the robot dynamics. An adaptive navigation function based controller is then designed that targets the trajectory planning problem where the task objective can be described as the desire to move from an initial condition to a goal configuration while avoiding known obstacles.