Person support apparatuses with load cell error detection

Patent metadata

Field	Value
Publication number	US-10260933-B2
Application number	US-201615185623-A
Country	US
Kind code	B2
Filing date	Jun 17, 2016
Priority date	Jun 30, 2015
Publication date	Apr 16, 2019
Grant date	Apr 16, 2019

Abstract

A person support apparatus, such as a bed, stretcher, recliner, cot, or the like, includes a frame, a plurality of load cells, a support surface supported by the load cells, a detection circuit, and a controller. The controller determines if any of the load cells are in an error state based upon information from the detection circuit. If the load cells include memory having calibration data stored therein, the controller communicates with the memory and uses the calibration data to determine an amount of weight supported on the surface. The detection circuit may include one or more Wheatstone bridges wherein the controller monitors voltages between midpoints of the Wheatstone bridges. The load cells may include an activation lead that is monitored by the detection circuit and a sensor lead that is used by the controller to determine an amount of weight supported on the patient support apparatus.

First claim

What is claimed is:

1. A person support apparatus comprising:
a frame;
a plurality of load cells supported by the frame, wherein each load cell includes a first set of leads for powering the load cell and a second set of leads for outputting a signal that varies as a function of a physical load applied to the load cell;
a support surface adapted to support thereon an occupant of the person support apparatus, the support surface being supported by the load cells such that a weight of the occupant is detectable by the load cells when the occupant is positioned on the support surface;
a detection circuit in communication with the first set of leads but not the second set of leads of the load cells; and
a controller in communication with the detection circuit, the controller adapted to determine if any of the plurality of load cells are in an error state based upon information from the detection circuit, the controller further adapted to output an error signal if one or more of the plurality of load cells are in the error state, wherein the error state comprises one or more of the plurality of load cells not being electrically coupled to an activation power source.

2. The person support apparatus of claim 1 wherein the detection circuit detects changes in a total amount of electrical current supplied to all of the first sets of leads from the activation power source.

3. The person support apparatus of claim 2 wherein the controller determines that one or more of the plurality of load cells are not electrically coupled to the activation power source if the total amount of electrical current supplied to all of the first sets of leads is outside of a predetermined range.

4. The person support apparatus of claim 3 wherein the predetermined range is a function of the number of load cells in the plurality of load cells.

5. The person support apparatus of claim 1 wherein the detection circuit detects changes in electrical current for each of the first sets of leads.

6. The person support apparatus of claim 5 wherein the controller is adapted to identify individual ones of the plurality of load cells that are present.

7. The person support apparatus of claim 6 wherein the controller identifies an individual one of the plurality of load cells as being present if an amount of electrical current supplied to the first set of leads to the individual one of the plurality of load cells falls within a predetermined range.

8. The person support apparatus of claim 1 wherein the detection circuit includes a plurality of switches controlled by the controller, each one of the switches being arranged in series with a corresponding one of the plurality of load cells.

9. The person support apparatus of claim 1 further comprising:
a plurality of load cell memories, wherein each of the plurality of load cell memories is physically coupled to a respective one of the plurality of load cells, each load cell memory including first calibration data regarding the respective load cell stored therein, the first calibration data generated before the respective load cell is installed in the person support apparatus;
a person support apparatus memory containing second calibration data regarding the plurality of load cells, the second calibration data generated after the plurality of load cells are installed in the person support apparatus; and
wherein the controller is adapted to use the first calibration data and the second calibration data to determine the weight of the occupant.

10. The person support apparatus of claim 9 wherein the person support apparatus is one of a bed, a recliner, a cot, and a stretcher.

11. The person support apparatus of claim 10 wherein the controller is further adapted to use the second calibration data to calibrate a replacement load cell when the replacement load cell is installed in the person support apparatus that replaces one of the plurality of load cells.

12. The person support apparatus of claim 11 wherein the controller is adapted to not use the first calibration data when the replacement load cell is installed in the person support apparatus.

13. The person support apparatus of claim 11 wherein the controller calibrates the replacement load cell without requiring any calibration measurements to be taken regarding the replacement load cell after the replacement load cell is installed in the person support apparatus.

14. The person support apparatus of claim 1 wherein a first one of the plurality of load cells is included within a first Wheatstone bridge, a second one of the plurality of load cells is included within a second Wheatstone bridge, the first and second Wheatstone bridges are included within a third Wheatstone bridge, and the controller monitors voltages between midpoints of each of the first, second, and third Wheatstone bridges.

15. The person support apparatus of claim 14 wherein the controller uses the voltage between the midpoints of the first Wheatstone bridge and the voltage between the midpoints of the second Wheatstone bridge when determining the weight of the occupant.

16. The person support apparatus of claim 15 wherein the controller uses the voltage between the midpoints of the third Wheatstone bridge to determine if a second error state exists for at least one of the first and second load cells when no weight is being exerted on the support surface by the occupant, the second error state being different from the error state.

17. The person support apparatus of claim 15 further including a detection circuit in communication with the first and second load cells and the controller, wherein the controller is further adapted to determine if an error state exists for at least one of the first and second load cells based upon information from the detection circuit.

18. The person support apparatus of claim 17 wherein the error state includes an electrical disconnection of the first load cell from the controller.

19. The person support apparatus of claim 17 further including an activation voltage source coupled to endpoints of the first and second Wheatstone bridges, wherein the detection circuit monitors a total amount of electrical current flowing from the activation voltage source to the endpoints of the first and second Wheatstone bridges.

20. The person support apparatus of claim 15 wherein the controller stores first calibration data for the first load cell and second calibration data for the second load cell in a memory on board the person support apparatus.

Assignees

• Stryker Corp

Inventors

• Kostic Marko N
• Hayes Michael Joseph
• Brosnan Daniel Vincent
• Furman Aaron Douglas
• Vanderplas Jason A

Classifications

• G01G23/01

  Testing or calibrating of weighing apparatus · CPC title

• G01G19/445 Primary

  in a horizontal position · CPC title