Tip-over avoidance algorithm for modular mobile manipulator

In this paper, a tip-over avoidance algorithm is proposed for a modular mobile manipulator. The primary application of the modular mobile manipulator is to assist urban search and rescue in unstructured environments. The modular mobile manipulator has five Degree of Freedom (DoF) on the manipulator and six DoF on the mobile base. A dynamic model of the modular mobile manipulator for real-time simulation is constructed in MapleSimTM. A frequently occurring problem associated with the mobile manipulator moving on uneven terrain is the tip-over. The tip-over phenomena is due to the fact that the torque created by the center of mass of the mobile manipulator is toward the outside of the supporting boundary. The tip-over avoidance algorithm is developed such that the center of mass of the mobile manipulator is controlled actively to balance the forces acting on the supporting boundary of the mobile manipulator. The algorithm not only provides tip-over avoidance but also balances the ground forces. The effectiveness of the proposed tip-over avoidance algorithm has been evaluated through simulations, and the results are reported in this paper.