Nonlinear Disturbance Decoupling for a Mobile Robotic Manipulator Over Uneven Terrain

This paper considers the nonlinear disturbance decoupling problem for a robotic manipulator that is mounted on a mobile platform. A mobile manipulation system offers a dual advantage of mobility offered by a mobile platform and dexterity offered by the manipulator. In this work, the tracking and nonlinear disturbance decoupling problems are studied with particular focus on disturbances due to uneven terrain. We show that this system possesses the necessary geometric structure for complete disturbance decoupling between the outputs and disturbances. The disturbances are modeled as changes in the effect of gravitational forces on the mobile manipulator due to its motion over a uneven terrain. Simulation results illustrate complete disturbance decoupling even in the presence of significant disturbances using the designed nonlinear controller.