Reconfigurable footprint mechanism for omnidirectional vehicles

A vehicle for locomotion over a surface under the control of a user, the vehicle comprising:

• a support;
• a plurality of members coupled to the support and characterized by a configuration, each member moveable about a common axis fixed with respect to the support and substantially perpendicular to the surface;
• a plurality of wheels, each wheel coupled to one of the members, each wheel having a center of mass, each wheel having at least one point of contact with the surface, the points of contact of the plurality of wheels having a specified spatial relationship such that the specified spatial relationship is reconfigurable, before and during motion of the assembly;
• and
• at least one sensor for measuring a physical quantity characterizing at least one of the configuration of the members, the motion of the wheel assembly, and the forces acting upon the wheel assembly;
• an input for receiving movement specification from a user;
• at least one wheel actuator for driving at least one of the plurality of wheels;
• and
• a processor for controlling the at least one actuator on the basis of the movement specification from the user and from the measured physical quantity.

A method of preventing a vehicle from tipping over while stationary, the vehicle having a support, a plurality of members, a plurality of moveable wheels and a controller, each wheel coupled to a member, each member moveable about a common axis with respect to the support, the method comprising the following steps:

• setting an initial vehicle footprint;
• applying a load to the vehicle;
• sensing instantaneous forces acting upon each of the plurality of wheels;
• calculating the mass centroid of the vehicle;
• moving the members about the common axis for reconfiguring the vehicle footprint such that a stability margin is optimized;
• and
• repeating the steps to account for time variable loads.

A method of improving the maneuverability of a vehicle, the vehicle having a support, a plurality of members, a plurality of moveable wheels and a controller, each wheel coupled to a member, each member moveable about a common axis fixed with respect to the support, the method comprising the following steps:

• sensing a current vehicle footprint;
• calculating a new vehicle footprint;
• and
• moving the members about the common axis to reconfigure the current vehicle footprint to the new vehicle footprint.

A method of improving the efficiency of a vehicle by changing the transmission ratio of the vehicle, the vehicle having a support, a plurality of members, a plurality of moveable wheels and a controller each wheel coupled to a member, each member moveable about a common axis fixed with respect to the support, the method comprising the following steps:

• sensing a current vehicle footprint;
• calculating a new vehicle footprint;
• and
• moving the members about the commons axis to reconfigure the current vehicle footprint to the new vehicle footprint.