We describe in this paper a new motion planning approach for a non-holonomic mobile robot moving on a uneven terrain and subject to strong physical interaction constraints. The novelty of this method is that it deals with the dynamics of the robot and its physical interactions with the terrain at the planning time, together with the kinematic and the geometric constraints of the task. The planner basically combines a \it geometry based reasoning strategy operating on a subset of the configuration space of the robot, and a \it local continuous motion generation technique based on the use of a physical model of the task. We will describe each level and its corresponding models, and present how they are integrated in order to find safe and executable motions for a rover.