Mobile robot having an improved suspension system

1. A mobile robot configured to drive on a surface with irregularities, comprising:

a chassis having a front end facing a forward direction of travel of the mobile robot, a back end, a first side, and a second side;

a first drive wheel rigidly affixed to the chassis proximate the first side and interconnected to at least one motor to propel the first drive wheel;

a second drive wheel rigidly affixed to the chassis proximate the second side and interconnected to the at least one motor to propel the second drive wheel;

a first caster assembly rigidly affixed to the chassis proximate the front end of the chassis; wherein the first caster assembly includes a first swivel mechanism to which a first caster wheel is rotatably affixed via a rigid interconnection member to rotate about a first swivel axis; and

a second caster assembly rigidly affixed to the chassis proximate the back end of the chassis; wherein the second caster assembly includes a second swivel mechanism to which a second caster wheel is rotatably affixed via a compliant interconnection member to rotate about a second swivel axis;

a laser-radar sensor located proximate the front end of the chassis configured to provide sensor data to a robot controller for navigation of the mobile robot;

wherein when the at least one motor propels the first and second drive wheels, thereby causing the mobile robot to drive on the surface, the compliant interconnection member of the second caster assembly absorbing the irregularities in the surface and the rigid interconnection member of the first caster assembly maintaining the front end of the chassis level with the surface to provide a consistent scan plane for the laser-radar sensor.

2. The mobile robot of claim 1 further including a platform supported by the chassis and configured to carry a load.

3. The mobile robot of claim 2 wherein the at least one motor includes a first motor connected to the first drive wheel via a first axle and a second motor connected to the second drive wheel via a second axle, thereby allowing the first and second drive wheels to be propelled independently.

4. The mobile robot of claim 3 wherein the chassis includes a bottom surface having a first cavity in which the first caster assembly is disposed and a second cavity in which the second caster assembly is disposed.

5. The mobile robot of claim 4 wherein the first swivel mechanism is rigidly affixed to a base of the first cavity and the rigid interconnection member includes a bracket which is rotatably connected at a first end to the first swivel mechanism and at a second end of the bracket the first caster wheel is connected.

6. The mobile robot of claim 5 wherein the second swivel mechanism is rigidly affixed to a base of the second cavity and the compliant interconnection member includes a spring which is rotatably connected at a first end to the second swivel mechanism and at a second end of the spring the second caster wheel is connected.

7. The mobile robot of claim 6 wherein the spring is a torque spring.

8. The mobile robot of claim 1 wherein the first and second drive wheels are positioned between the first caster assembly proximate the front end of the chassis and the second caster assembly proximate the back end of the chassis.

9. The mobile robot of claim 1 wherein the second swivel mechanism is affixed to the chassis and wherein the second swivel mechanism is positioned above the compliant interconnection member relative the surface.