High-level control of a mobile manipulator for door opening

In this paper, off-the-shelf algorithms f o r force/torque control are used in the context of mobile manipulation (i.e. coordinated mot ion of a mobile robot base and the a r m mounted o n top of it). In particular, the task of opening a door is studied. To make the solution robust, as f e w assumptions as possible are made. B y using relaxation of forces as the basic level of control, more complex information can be derived f r o m the resulting motion. In our system, the radius and the centre of rotation of the door are estimated online. This enables the complete sys tem t o have a higher degree of autonomy in a n unknown environment. In addit ion, the redundancy of the robot is exploited in such a way as t o drive the sys tem towards a desired configuration. The framework of hybrid dynamic systems is used to implement the algorithm which gives a theoretically sound framework f o r analysing the sys tem with respect t o safety and functionality. The integration of the above approaches results in a sys tem which can robustly locate und grasp the handle und then open the door.