Method for driving a wheeled carriage

A method for driving a power assisted wheeled carriage used for supporting and transporting a person in a substantially horizontal position, the carriage including a patient support having a length, opposing ends of the length comprising a head end and a foot end of said patient support, a wheeled base having a length and supporting said patient support and enabling movement of said patient support, castered wheels mounted at each opposing corner at each opposing end of said wheeled base, an auxiliary wheel mechanism secured to said wheeled base and for positioning at least one auxiliary wheel into a first position contacting a floor below the wheeled carriage and into a second raised position out of engagement with the floor, a drive motor assembly including a drive motor for driving said auxiliary wheel in one of a first direction and a second opposing direction, said auxiliary wheel being located at a position toward a central section inwardly with respect to said castered wheels of said carriage, and a battery for supplying power to said drive motor, the method comprising the steps of, when said carriage is in a rest position:

• sensing that a power cable is not connected to an external AC power supply;
• sensing that a brake of the wheeled carriage is in a released position;
• sensing that the charge of the battery exceeds a minimum charge value;
• sensing that the auxiliary wheel is in engagement with the floor;
• the method further comprising when 1) the power cable is not connected to the external AC power supply, 2) the brake is in the released position, 3) the charge of the battery exceeds the minimum charge value, and 4) the auxiliary wheel is in engagement with the floor, the steps of:
• (a) sensing a drive signal for driving said at least one auxiliary wheel in a first direction;
• (b) calculating a power signal based on the drive signal;
• (c) applying the power signal to the drive motor to drive the auxiliary wheel;
• and
• (d) repeating steps (a)–(d), until the drive signal is no longer sensed.

A method for driving a power assisted wheeled carriage used for supporting and transporting a person in a substantially horizontal position, the carriage including a patient support having a length, opposing ends of the length comprising a head end and a foot end of said patient support, a wheeled base having a length and supporting said patient support and enabling movement of said patient support, castered wheels mounted at each opposing corner at each opposing end of said wheeled base, an auxiliary wheel mechanism secured to said wheeled base and for positioning at least one auxiliary wheel into a first position contacting a floor below the wheeled carriage and into a second raised position out of engagement with the floor, a drive motor assembly including a drive motor for driving said auxiliary wheel in one of a first direction and a second opposing direction, said auxiliary wheel being located at a position toward a central section inwardly with respect to said castered wheels of said carriage, and a battery for supplying power to said drive motor, the method comprising the steps of, when said carriage is in a rest position and an on/off switch enables driving of said auxiliary wheel:

• sensing that a brake of the wheeled carriage is in a released position;
• sensing that the auxiliary wheel is in engagement with the floor;
• the method further comprising when 1) the brake is in the released position, and 2) the auxiliary wheel is in engagement with the floor,
• the step of sensing a drive signal from a drive member controlled by an operator for driving said at least one auxiliary wheel and providing a power signal to said drive member to drive said auxiliary wheel in one of the first direction and the second opposing direction.