Path planning for image-based control of wheeled mobile manipulators

We address the problem of incorporating path planning with image-based control of a wheeled mobile manipulator (WMM) performing visually-guided tasks in complex environments. The WMM consists of a wheeled (non-holonomic) mobile platform and an on-board robotic arm equipped with a camera mounted at its end-effector. The visually-guided task is to move the WMM from an initial to a desired location while respecting image and physical constraints. We propose a kinodynamic planning approach that explores the camera state space for permissible trajectories by iteratively extending a search tree in this space and simultaneously tracking these trajectories in the WMM configuration space. We utilize weighted pseudo-inverse Jacobian solutions combined with a null space optimization technique to effectively coordinate the motion of the mobile platform and the arm. We also present the preliminary results obtained by executing the planned trajectories on a real WMM system via a decoupled control scheme where the on-board arm is servo controlled along the planned feature trajectories while the mobile platform is simultaneously controlled along its trajectory using a state feedback tracking method.