Methods and apparatuses for controlling angular orientations of a person support apparatus

1. A method for controlling an angular orientation of a person support apparatus including a support surface having a bladder portion containing fluidized particulate material configured for migration within the bladder portion along a bottom surface of the bladder portion due to a gravitational pull toward an end of the person support apparatus, an upper frame, and a base frame, the method comprising:

adjusting a height of the upper frame with respect to the base frame with at least one of a first actuator and a second actuator at respective first and second actuator speeds;

determining a dynamic angular orientation of the upper frame with respect to the base frame based on at least one of an operating characteristic of the first actuator and an operating characteristic of the second actuator;

determining a corrected angular orientation based on the dynamic angular orientation and a floor angle, wherein the floor angle is indicative of an orientation of the base frame sensed with respect to horizontal and is generated as a sensed output estimation;

comparing the corrected angular orientation with an orientation reference range, within which orientation reference range the fluidized particulate material maintains a predetermined depth distribution within the bladder portion to prevent bottoming out, the predetermined depth distribution comprising a layer of fluidized particulate material disposed on the bottom surface of the bladder portion with a first depth at a first end of the bladder portion and a second depth different from the first depth at a second end of the bladder portion such that an angle between the first depth and the second depth is within the orientation reference range; and

adjusting at least one of the first actuator speed and the second actuator speed when the corrected angular orientation is outside the orientation reference range until the corrected angular orientation is within the orientation reference range.

2. The method of claim 1 , wherein the fluidized particulate material contained within the bladder portion of the person support apparatus has the predetermined depth distribution in the bladder portion when the corrected angular orientation is within the orientation reference range.

3. The method of claim 1 , further comprising an initial step of determining the floor angle indicative of the orientation of the base frame with respect to horizontal based on a value generated from an inclinometer disposed on the person support apparatus.

4. The method of claim 1 , wherein at least one of the first actuator speed and the second actuator speed are adjusted and the dynamic angular orientation is determined as the upper frame transitions with respect to the base frame from a first height to a second height.

5. The method of claim 4 , wherein the dynamic angular orientation is determined at least partially based on one or more values generated from at least one of a first potentiometer associated with the first actuator and a second potentiometer associated with the second actuator.

6. The method of claim 1 , wherein:

the orientation reference range is measured relative to a reference position of the person support apparatus; and

the reference position is at 0.25° such that the person support apparatus is oriented with a foot end of the person support apparatus higher than a head end.

7. The method of claim 1 , wherein:

the orientation reference range is measured relative to a reference position of the person support apparatus; and

the reference position is in a range from about +0.1° to about −0.5° such that the person support apparatus is oriented with a foot end of the person support apparatus higher than a head end when the reference position is in a negative end of the range.

8. The method of claim 1 , wherein:

the orientation reference range is measured relative to a reference position of the person support apparatus; and

the orientation reference range is in at least one of the following ranges relative to the reference position:

a range from about −0.4 to about +0.4° relative to the reference position; and

a range from about −0.25° to about +0.25° relative to the reference position.

9. A method for controlling an angular orientation of a person support apparatus that includes a support surface having a bladder portion containing fluidized particulate material configured for migration within the bladder portion along a bottom surface of the bladder portion due to a gravitational pull toward an end of the person support apparatus, the method comprising:

actuating at least one of a first actuator and a second actuator, respectively coupled to the person support apparatus at a first end and a second end, at a respective first actuator speed and a second actuator speed to raise or lower a height of the person support apparatus;

receiving a first reading indicative of a first angular orientation of the first end of the person support apparatus with respect to the second end and relative to horizontal, wherein the first reading is at least generated from a first sensor and a second sensor respectively associated with the first actuator and the second actuator;

determining a corrected first reading indicative of the first angular orientation based on the first reading and a calibration of the person support apparatus configured to generate a sensed output estimation of an orientation of the person support apparatus with respect to horizontal;

comparing the corrected first reading and an orientation reference range within which orientation reference range the fluidized particulate material maintains a predetermined depth distribution within the bladder portion to prevent bottoming out, the predetermined depth distribution comprising a layer of fluidized particulate material disposed on the bottom surface of the bladder portion with a first depth at a first end of the bladder portion and a second depth different from the first depth at a second end of the bladder portion such that an angle between the first depth and the second depth is within the orientation reference range; and

actuating at least one of the first actuator and the second actuator automatically at a different speed when the corrected first reading is outside the orientation reference range until an adjusted corrected first reading indicative of an adjusted first angular orientation is within the orientation reference range.

10. The method of claim 9 , wherein the fluidized particulate material contained within the bladder portion of the person support apparatus has the predetermined depth distribution in the bladder portion when the corrected first reading is within the orientation reference range.

11. The method of claim 9 , wherein:

the first end comprises a foot end;

the second end comprises a head end; and

the orientation reference range is measured relative to a reference position of the person support apparatus; and

the reference position is at 0.25° such that the person support apparatus is oriented with the foot end of the person support apparatus higher than the head end.

12. The method of claim 9 , wherein the orientation reference range is in a range from about −0.4° to about +0.4° relative to a reference position.

13. The method of claim 9 , further comprising calibrating the person support apparatus to generate the calibration, the calibrating comprising:

calculating, automatically with an inclinometer, a floor angle associated with the person support apparatus relative to horizontal to generate the sensed output estimation of the orientation of the person support apparatus with respect to horizontal.

14. The method of claim 9 , wherein:

the first reading is generated from at least one of a first potentiometer associated with the first actuator and a second potentiometer associated with the second actuator; and

the method further comprises calibrating the person support apparatus to generate the calibration, the calibrating comprising calculating, automatically with an inclinometer, a floor angle associated with the person support apparatus relative to horizontal; and

determining the corrected first reading comprises calculating the corrected first reading based on the first reading and the floor angle.

15. The method of claim 14 , further comprising:

receiving input from at least one of the first potentiometer and the second potentiometer respectively in at least one of a first PID controller and a second PID controller;

outputting at least one of a first actuator drive signal from the first PID controller and a second actuator drive signal from the second PID controller; and

repeating the receiving and outputting steps until the adjusted corrected first reading indicative of the adjusted first angular orientation is within the orientation reference range.

16. The method of claim 9 , wherein:

the first reading is at least partially generated from a first potentiometer associated with the first actuator and a second potentiometer associated with the second actuator; and

actuating at least one of the first actuator and the second actuator comprises outputting a stroke length signal related to a stroke length for the respective first and second actuators, wherein the stroke length of the first actuator is an input with respect to the first potentiometer and the stroke length of the second actuator is an input with respect to the second potentiometer.

17. The method of claim 16 , further comprising:

receiving the respective stroke lengths for the first and second actuators associated with the corrected first reading as a respective input in at least one of a first PID controller and a second PID controller;

outputting at least one of a first actuator drive signal from the first PID controller and a second actuator drive signal from the second PID controller; and

repeating the receiving and outputting steps until the adjusted corrected first reading indicative of the adjusted first angular orientation is within the orientation reference range.

18. The method of claim 9 , wherein the first actuator is incremented at a first duty cycle speed that is at least double a second duty cycle speed at which the second actuator is incremented.

19. The method of claim 18 , wherein the first duty cycle speed is at a 10% pulse-width-modulation and the second duty cycle speed is at a 5% pulse-width-modulation.

20. A system for controlling an angular orientation of a person support apparatus that includes a support surface having a bladder portion containing fluidized particulate material configured for migration within the bladder portion along a bottom surface of the bladder portion due to a gravitational pull toward an end of the person support apparatus, the system comprising:

at least a first actuator associated with a head end as a first end and a second actuator associated with a foot end as a second end of the person support apparatus; and

an electronic control unit comprising a processor communicatively coupled to a non-transitory computer storage medium, wherein the non-transitory computer storage medium stores instructions that, when executed by the processor, cause the processor to:

actuate at least one of the first actuator and the second actuator at a respective first actuator speed and a second actuator speed to raise or lower a height of the person support apparatus;

receive, automatically with the electronic control unit, a first reading indicative of a first angular orientation of the first end of the person support apparatus with respect to the second end and relative to horizontal, wherein the first reading is generated from a first sensor and a second sensor respectively associated with the first actuator and the second actuator;

determine, automatically with the electronic control unit, a corrected first reading indicative of the first angular orientation based on the first reading and a calibration of the person support apparatus configured to generate a sensed output estimation of an orientation of the person support apparatus with respect to horizontal;

compare, automatically with the electronic control unit, the corrected first reading and an orientation reference range, within which orientation reference range the fluidized particulate material maintains a predetermined depth distribution within the bladder portion to prevent bottoming out, the predetermined depth distribution comprising a layer of fluidized particulate material disposed on the bottom surface of the bladder portion with a first depth at a first end of the bladder portion and a second depth different from the first depth at a second end of the bladder portion such that an angle between the first depth and the second depth is within the orientation reference range; and

actuate at least one of the first actuator and the second actuator, automatically with the electronic control unit, at a different speed when the corrected first reading is outside the orientation reference range until an adjusted corrected first reading indicative of an adjusted first angular orientation is within the orientation reference range.