Techniques for detecting a force acting on a base of a patient transport apparatus

1. A patient transport apparatus for use in loading and unloading into a cargo area of an emergency response vehicle, the patient transport apparatus comprising:

a base;

a support frame comprising a patient support surface configured to support a patient;

a lift mechanism interposed between the base and the support frame and being configured to move between a plurality of vertical configurations including an extended configuration and a retracted configuration, wherein the base and the support frame are separated by a first distance in the extended configuration and a second distance in the retracted configuration, and wherein the first distance is greater than the second distance;

a user interface configured for engagement by a user to generate a user input signal;

a sensor configured to generate a sensor input signal corresponding to a force acting on the base relative to the support frame; and

a controller coupled to the lift mechanism, the user interface, and the sensor, the controller being configured to:

determine if the force acting on the base has exceeded a predetermined threshold value based on the sensor input signal;

drive the lift mechanism in response to receiving the user input signal; and

interrupt driving of the lift mechanism between the extended configuration and the retracted configuration to stop motion of the lift mechanism in response to the sensor input signal exceeding the predetermined threshold value.

2. The patient transport apparatus of claim 1 , wherein the controller is configured to:

determine if the user input signal corresponds to a user override command; and

drive the lift mechanism toward the extended configuration or the retracted configuration in response to determining that the user input signal corresponds to the user override command.

3. The patient transport apparatus of claim 2 , wherein the user interface is configured to receive an extend input and a retract input.

4. The patient transport apparatus of claim 3 , wherein the controller is further configured to determine that the user input signal corresponds to the user override command in response to the user interface receiving the extend input or the retract input after interrupting driving of the lift mechanism.

5. The patient transport apparatus of claim 3 , wherein the user interface is configured to receive a user override input as the user input signal.

6. The patient transport apparatus of claim 5 , wherein the controller is further configured to determine that the user input signal corresponds to the user override command in response to the user interface receiving the user override input after interrupting driving of the lift mechanism.

7. The patient transport apparatus of claim 5 , wherein the controller is further configured to determine that the user input signal corresponds to the user override command in response to the user interface receiving the user override input a predetermined amount of time after interrupting driving of the lift mechanism.

8. The patient transport apparatus of claim 5 , wherein the controller is further configured to determine that the user input signal corresponds to the user override command in response to the user interface receiving the user override input after interrupting driving of the lift mechanism and a predetermined amount of time after no longer receiving the extend input or the retract input.

9. The patient transport apparatus of claim 1 , wherein the sensor is configured to generate the sensor input signal in response to sensing a load on the lift mechanism corresponding to the force acting on the base.

10. The patient transport apparatus of claim 1 , wherein the sensor is further defined as a first sensor, and the sensor input signal is further defined as a first sensor input signal, and wherein the patient transport apparatus further comprises a second sensor configured to generate a second sensor input signal corresponding to a presence of an object within an envelope defined as adjacent to the base, and wherein the controller is further configured to:

determine if an object present within the envelope will come into contact with the base based on the second sensor input signal; and

interrupt driving of the lift mechanism between the extended configuration and the retracted configuration in response to determining that the object present within the envelope will come into contact with the base.

11. The patient transport apparatus of claim 10 , wherein the controller is further configured to determine if the object present within the envelope will come into contact with the base based on a distance between the object and the base.

12. The patient transport apparatus of claim 10 , wherein the controller is further configured to determine if the object present within the envelope will come into contact with the base based on a distance between the object and the base and a speed of the object.

13. The patient transport apparatus of claim 1 , wherein the lift mechanism comprises an actuator and wherein the controller is configured to drive the lift mechanism by driving the actuator.

14. The patient transport apparatus of claim 13 , wherein the controller is coupled to a power supply and wherein the controller is configured to drive the actuator by controlling power provided to the actuator from the power supply.

15. The patient transport apparatus of claim 14 , wherein the controller is configured to interrupt driving of the lift mechanism by limiting the power provided to the actuator from the power supply.

16. The patient transport apparatus of claim 1 , wherein the user interface is configured to generate an alert in response to the controller interrupting driving of the lift mechanism.

17. The patient transport apparatus of claim 1 , wherein the base comprises at least three wheels.