US Patent 10045893 Patient transport apparatus with controllable auxiliary wheel assembly

A patient transport apparatus transports a patient over a surface. The patient transport apparatus comprises a base and support wheels coupled to the base. An auxiliary wheel assembly is coupled to the base to influence motion of the patient transport apparatus over the surface to assist caregivers. The auxiliary wheel assembly comprises auxiliary wheels and an actuator operably coupled to the auxiliary wheels. A controller adjusts the actuator based on input from a sensing system so that frictional forces acting between the auxiliary wheels and the surface are sufficient for steering and maneuvering of the patient transport apparatus, without sacrificing stability of the patient transport apparatus.