Extended Factitious Force Approach for Control of a Mobile Manipulator Moving on Unknown Terrain

In the paper a new control algorithm for mobile manipulators with skid–steering platform, moving on unknown terrain, has been introduced. The mobile manipulator consists of a skid–steering mobile platform and a 2R rigid manipulating arm mounted on the platform. Due to under–actuation of such mobile platforms, the concept of factitious force (which does not exist in reality and is assumed to be always 0) has been utilised. Presented control law, in adaptive and robust version, guarantees asymptotically fast convergence of tracking errors to 0, which has been proved in the article. Simulations, which have been conducted for object of considerations, confirm that the developed control law works properly even in terrain which parameters are unknown and piece–wise constant.