In this paper, off-the-shelf algorithms for force/torque control are used in the context of mobile manipulation, in particular, the task of opening a door is studied. To make the solution robust, as few assumptions as possible are made. By using relaxation of forces as the basic level of control more complex information can be derived from the resulting motion. In our system, the radius and centre of rotation of the door are estimated online. This enables the complete system to have a higher degree of autonomy in an unknown environment. In addition, the redundancy of the robot is exploited in such a way to drive the system towards a desired configuration. The framework of hybrid dynamic systems is used to implement the algorithm which gives a theoretically sound framework for analysing the system with respect to safety and functionality. The integration of the above approaches results in a system which can robustly locate and grasp the handle and then open the door