OPTIMAL AND SUBOPTIMAL MOTION PLANNING FOR COLLISION-AVOIDANCE OF MOBILE ROBOTS IN NONSTATIONARY ENVIRONMENTS

An optimal control formulation of the problem of collision avoidance o f mobile robots moving in terrains containing moving obstacles is pres ented. A dynamic model of the mobile robot and the dynamic constraints are derived. Collision avoidance is guaranteed if the minimum distanc e between the robot and the objects is nonzero. A nominal trajectory i s assumed to be known from off-line planning. The main idea is to chan ge the velocity along the nominal trajectory so that collisions are av oided. Furthermore, time consistency with the nominal plan is desirabl e. Two solutions are obtained: (1) A numerical solution of the optimiz ation problem and a perturbation type of control to update the optimal plan and (2) A computationally efficient method giving near optimal s olutions. Simulation results verify the value of the proposed strategi es and allow for comparisons.