Robotic platform

1. A method of negotiating an obstacle, the method comprising:

driving an articulated vehicle along a drive direction over a surface, the vehicle comprising:

a rigid main frame having forward and rearward portions and right and left sides;

a drive system supporting the rigid main frame with the frame spaced from the surface, the drive system configured to propel the articulated vehicle over the surface;

right and left arms, each arm having a proximal end and a distal end, the proximal end of each arm being pivotally coupled to the forward portion of the rigid main frame about a transverse axis generally perpendicular to the sides of the rigid main frame and the distal end being pivotable 360° about the transverse axis without interference from other parts of the articulated vehicle; and

an articulator motor disposed on the rigid main frame and coupled to each arm for pivoting each arm about the transverse axis;

driving, while the rigid main frame remains rigid, the articulated vehicle to approach an obstacle with the forward portion of the articulated vehicle;

pivoting, while the rigid main frame remains rigid, the arms about the transverse axis from a stowed position next to the main frame downward and away from the main frame, thereby supporting the rigid main frame on a length of at least one of the arms extending from the proximal end to the distal end thereof and lifting the rearward portion of the main frame above the support surface and above the transverse axis;

pivoting, while the rigid main frame remains rigid, the arms to drive the main frame past a vertical position, causing the articulated vehicle to fall over substantially against the object and thereby invert the main frame; and

driving, while the rigid main frame remains rigid, onto the obstacle.

2. The method of claim 1 , further comprising pivoting the arms to raise the main frame off the surface and at least partially onto the obstacle.

3. The method of claim 1 , further comprising pivoting the arms to extend a base of the vehicle.

4. The method of claim 1 , further comprising pivoting the arms back at least to the stowed position and driving toward the object.

5. The method of claim 1 , further comprising pivoting the arms back through the stowed position to a non-stowed position at an angle with respect to the main frame, raising and supporting the main frame on the arms.

6. The method of claim 1 , further comprising:

pivoting the arms to an extended position substantially parallel with the main frame, raising and supporting the forward portion of the main frame on the arms; and then

driving onto the object.

7. The method of claim 6 , wherein the combination of main frame and the arms in the extended position provide an extended base sufficiently long to span a minimum of two stair steps of 7 in (17.8 cm) rise by 11 in (27.9 cm) tread stairs at all times, and the center of gravity of the articulated vehicle is located so that the articulated vehicle remains statically stable as it climbs stair steps of 7 in (17.8 cm) rise by 11 in (27.9 cm) tread stairs.

8. The method of claim 1 , further comprising:

pivoting the arms through an extended position substantially parallel with the main frame, raising and supporting the forward portion of the main frame on the arms; and

driving onto the object.

9. The method of claim 1 , further comprising differentially driving the robot, wherein the drive system comprises:

right and left drive elements disposed on corresponding sides of the main frame; and

right and left drive motors disposed on the main frame and differentially driving the respective drive elements.

10. The method of claim 1 , wherein a center of mass of the articulated vehicle is contained within an envelope of the 360 degree rotation of the arms.

11. The method of claim 1 , wherein pivoting the arms about the transverse axis from a stowed position next to the main frame downward and away from the main frame includes applying torque to the arms to balance the articulated vehicle on the arms while raising the rearward portion of the main frame.

12. The method of claim 1 , wherein pivoting the arms about the transverse axis from a stowed position next to the main frame downward and away from the main frame includes applying torque to the arms to balance the articulated vehicle on the arms while raising the rearward portion of the main frame.