Stair climbing robot

A robot vehicle adapted to climb stairs and similar obstacles comprising:

• an elongated chassis having a front, back, sides and top and a pair of front wheels rotatably mounted on opposite sides thereof;
• a pair of beams rotatably mounted on opposite sides of said chassis each beam extending from the center toward the rear of the chassis whereby the axis of rotation of each beam is contained in a plane perpendicular to the planes containing each of said front wheels;
• a first and a second pair of wheels, one rotatably mounted at each end of each beam whereby when said beams are horizontal and said six wheels rest on a horizontal surface the longitudinal axis of said chassis will be substantially horizontal;
• reversible first and second front drive means coupled respectively to each of said front wheels for selectively rotating said wheels;
• reversible first and second rear drive means coupled respectively for selectively rotating each pair of wheels mounted on each beam whereby each wheel in a pair is rotated in the same direction and the same rotational velocity;
• reversible wheel over wheel drive means coupled to each beam for selectively causing said beams to rotate in the same direction and at the same velocity;
• and
• control means coupled to each of said drive means for sensing and controlling the direction of rotation and rotational velocity of each wheel and for engaging the wheel over wheel drive means to rotate said beams in one direction at a first rotational velocity and to rotate each of said pairs of wheels in an opposite direction at the same rotational velocity.