Coordinated motion control of a nonholonomic mobile manipulator for accurate motion tracking

Standard manipulators are restrained in many applications due to their limited working ranges. Adding mobile platforms, in particular nonholonomic mobile platforms, can expediently enlarge their working ranges but also introduces new challenges. The problem of the existing control methods for nonholonomic mobile manipulators is that they leave out the consideration of the differences between the mobile platform and the manipulator such as the dynamics differences and working condition differences. This may consequently result in some unnecessarily large errors for the motion tracking in the implementation. To address this problem, this paper proposes a new practical control method using the adaptive motion distribution and coordination between the mobile platform and manipulator to minimize the errors of the motion control and also automatically handle some unexpected events. The effectiveness and advantages of the proposed method were demonstrated through both simulation and experimental results.