A mobile robotic manipulator, i.e. a manipulator mounted on a vehicle, is a very useful system for tasks in dangerous environments. Unfortunately the use of a wheeled vehicle introduces non-holonomic constraints, and the combination of a vehicle and a manipulator generally introduces kinematic redundancy. The goal of this paper is to propose a method to determine a feasible path between two fixed configurations for a mobile manipulator whose vehicle is non-holonomic. For this purpose, we write the global displacement of the system in a symbolic way, using two representation tools: homogeneous matrices and dual quaternions. Then, we compute the corresponding joint parameters to make the desired displacement coincide with the computed symbolic displacement. The method is described and some simulation results are presented.

A mobile manipulator, composed of a manipulator mounted on a vehicle, is a very useful system to achieve tasks in dangerous environments. Unfortunately it is a very complicated system to model and control. One solution is to control the manipulator and the vehicle independently with advanced control schemes. In particular motions of the vehicle on uneven terrains induce disturbances on the arm behaviour that must be either taken into account or rejected by the arm control scheme. The aim of this paper is to compare the robustness of hybrid position/force and external force control structures with respect to external disturbances, for a manipulator mounted on a vehicle. The principles of both control structures are recalled. Some theoretical analysis tends to prove the superiority of the external control structure. This is confirmed by experiments with our real testbed. Results are presented in the form of graphs.

A mobile manipulator, composed of a manipulator mounted on a vehicle, is a very useful system to achieve tasks in dangerous environments. However, it is a very complicated system to model and control. The use of a wheeled vehicle generally introduces nonholonomic constraints, and the combination of a vehicle and a manipulator generally introduces some kinematic redundancy. The aim of this paper is to investigate the use of dual quaternions for the motion generation of a mobile manipulator with a nonholonomic vehicle. In this preliminary work, only planar cases are considered. Therefore, the principles of the planar quaternion theory are recalled. The description of the system in the planar quaternion space is developed. Some simulation results are then presented.