Method for surmounting an obstacle by a robot vehicle

A method of operating a vehicle supported on front and rear wheels connected to the vehicle body by respective front and rear struts, the front struts and the rear struts being independently rotatable about respective forward and rear axes, wherein the axes intersect the vehicle body in a direction transverse to the direction of vehicle travel, said method comprising the steps of:

• rotating the front struts simultaneously about their transverse axis with respect to the vehicle body from an original angular position to move the front wheels forward so as to shift most of the vehicle weight onto the rear wheels;
• driving the vehicle forward by powered rotation of at least some of said wheels so as to drive the now lightly-loaded front wheels on top of an obstacle;
• returning the front forks to their original angular position while rotating the rear struts simultaneously about their transverse axis with respect to the vehicle body from an original angular position to move the rear wheels rearward so as to shift most of the vehicle weight onto the front wheels;
• driving said vehicle forward by powered rotation of at least some of said wheels so as to drive the now lightly-loaded rear wheels on top of the obstacle;
• returning the rear forks to their original angular position while rotating the front struts simultaneously about their transverse axis with respect to the vehicle body to move the front wheels forward to provide stability during descent;
• driving the vehicle forward by powered rotation of at least some of said wheels until clear of the obstacle;
• and,
• rotating the front and rear struts so as to uniformly distribute the vehicle weight between the front and rear wheels once the vehicle is again on relatively level terrain.