Dynamics modeling and control of an armed Ballbot with stabilizer

The combination of mobile platform and a manipulator which is known as a mobile manipulator can be used in lots of applications. Motion control with respect to stability of dynamically stable mobile manipulators is one the interesting challenges in robotics. Mobile robots with small base are capable of moving in limited space. A Ballbot is an underactuated system with nonholonomic dynamic constraints. It is as tall as human height until could interact by people whereas a Ballbot has not been equipped with a manipulator for grasping objects. In this paper, it has been equipped with a PUMA type manipulator which gives to the proposed robot the capability of object manipulation. Because of passive joints, Ballbot cannot maintain stability and following desired end-effector trajectory. So, a 2 DOF stabilizing pendulum is used to help the stability of a system and make the manipulator practical. As a result, dynamics equations of the assumed mobile robot are presented. Furthermore, a model-based controller is described to move the end-effector along the desired path/trajectory and maintains the system balance. Obtained results show the capabilities of the proposed control algorithm in satisfying the desired objectives.