Trajectory optimization of nonholonomic mobile manipulators departing to a moving target amidst moving obstacles

摘要

How to plan the optimal trajectory of nonholonomic mobile manipulators in dynamic environments is a significant and challenging task, especially in the system with a moving target. This paper presents trajectory optimization of a nonholonomic mobile manipulator in dynamic environment pursuing a moving target. Full nonlinear dynamic equations of the system considering the nonholonomic constraints of wheels are presented. Then, dynamic motion planning of the system is formulated as an optimal control problem considering moving obstacle avoidance conditions. Accordingly, a new formulation of dynamic potential function was proposed based on the dynamic distance between colliding objects. In addition, an appropriate boundary value for a moving target was defined, and the resulted boundary value problem was solved to optimize the trajectory of the system. To solve the problem, an indirect solution of optimal control was applied which leads to transform the optimal control problem into a set of coupled differential equations. To demonstrate the efficiency and applicability of the method a number of simulations and experiments was performed for a spatial nonholonomic mobile manipulator.