Granted Patent B2

US 12,533,971 · App. 17/384,925 · Granted Jan 27, 2026

Inventors: Stewart M. Coulter (Bedford, NH); Brian G. Gray (Manchester, NH); Dirk A. van der Merwe (Canterbury, NH); Susan D. Dastous (Litchfield, NH); Daniel F. Pawlowski (Raymond, NH)

Assignee: DEKA Products Limited Partnership

B60L50/60A61G5/04A61G5/041B60L15/20B60L15/2045B60L50/50B60W10/08B60W10/184B60W10/20B60W30/02B60W30/09B60W30/143B60W50/10B62K5/003G05B13/048G05D1/0077G05D1/0238B60L2200/34B60L2240/423B60L2240/461B60L2250/24B60W2420/403B60W2420/408B60W2520/16B60W2520/18B60W2530/10B60W2554/00B60W2710/083B60W2720/106B60W2720/24B60Y2400/112G01P15/02Y02T10/64Y02T10/72

Abstract

Claims (59)

1 . A system for stabilizing a mobility device, the mobility device having at least one sensor, drive wheels, the drive wheels having wheel motor drives, the mobility device having a seat, the seat having a seat motor, the seat motor having a seat motor current, the system comprising:

a weight processor including a weight estimation processor configured for estimating the weight or change in weight of a load on the mobility device;

a controller gains processor configured for choosing a default value or values for a center of gravity of the mobility device and computing controller gains based at least on a dynamic state and/or change thereof based on the weight or the change in weight and the center of gravity; and

a wheel command processor configured for modifying a wheel command based on a change in a location of the center of gravity and applying the controller gains in said wheel command processor to control a wheel speed of the mobility device.

2 . The system as in claim 1 wherein the weight processor comprises computer instructions configured for detecting unstable situations comprising:

collecting, by the at least one sensor, pitch rate data of the mobility device;

computing pitch rate frequency of the collected pitch rate data based on a rolling discrete Fast Fourier transform;

determining, from the pitch rate frequency, values indicating instability;

filtering the pitch rate frequencies based at least on the determined values;

squaring the filtered pitch rate frequencies; and

analyzing the squared pitch rate frequencies based at least on pre-selected profiles of potential instability.

3 . The system as in claim 1 wherein the weight estimation processor comprises computer instructions configured for:

issuing commands to the seat motor to raise the load while measuring the torque required to raise the seat and the load; and

computing the weight of the load based at least on the torque.

4 . The system as in claim 1 wherein the controller gains comprise a range of discrete values.

5 . The system as in claim 1 wherein the controller gains comprise a range of analog values.

6 . The system as in claim 1 wherein the weight processor comprises computer instructions configured for issuing commands to adjust stability of the mobility device based at least on a change in the load.

7 . The system as in claim 1 wherein the estimating the weight or change in weight comprises computing the weight estimate based at least on the seat motor current.

8 . The system as in claim 1 wherein the estimating the weight or change in weight comprises measuring the load on the mobility device comprising:

lifting the seat and the load while measuring a first torque required to lift the seat and the load; and

estimating a second torque, based on the motor current, required to lift the load.

9 . The system as in claim 1 wherein the estimating the weight comprises computing the weight estimate based at least on a height of the seat, the seat motor current, and a pre-selected threshold value associated with the seat motor.

10 . The system as in claim 1 wherein the estimating the weight comprises computing a continuous estimate of the weight based at least on continuous monitoring of a current signal from the seat motor.

11 . A method for stabilizing a mobility device, the mobility device having at least one sensor, at least one user interface, drive wheels, the drive wheels having wheel motor drives, the mobility device having a seat, the seat being associated with a seat motor, the seat motor being associated with a seat motor current, the method comprising:

estimating the weight or change in weight of a load on the mobility device;

choosing a default value or values for a center of gravity of the mobility device;

computing controller gains based at least on a dynamic state and/or change thereof based on the weight or the change in weight and the center of gravity;

modifying a wheel command based on a change in a location of the center of gravity; and

applying the controller gains to control a wheel speed of the mobility device.

12 . The method as in claim 11 further comprising detecting unstable situations comprising:

collecting, by the at least one sensor, pitch rate data of the mobility device;

computing pitch rate frequency of the collected pitch rate data based on a rolling discrete Fast Fourier transform;

determining, from the pitch rate frequency, values indicating instability;

filtering the pitch rate frequencies based at least on the determined values;

squaring the filtered pitch rate frequencies; and

analyzing the squared pitch rate frequencies based at least on pre-selected profiles of potential instability.

13 . The method as in claim 11 further comprising:

issuing commands to the seat motor to raise the load while measuring the torque required to raise the seat and the load; and

computing the weight of the load based at least on the torque.

14 . The method as in claim 11 further comprising:

automatically estimating the weight of the load on the mobility device;

determining the center of gravity for the mobility device and the load;

computing gains based at least on the load and the center of gravity; and

computing the default value or values based at least on the gains on the weight or a weight change.

15 . The method as in claim 11 further comprising:

(1) positioning the load on the mobility device;

(2) moving the mobility device/load into a balance mode, the balance mode characterized by elevating the mobility device/load above a standard seated position;

(3) measuring data including a pitch angle required to maintain the balance mode at a pre- selected position of at least one wheel cluster operably coupled with the mobility device and a pre-selected position of a seat operably coupled with the mobility device;

(4) moving the mobility device/load to a plurality of pre-selected points;

(5) repeating step (3) at each of the plurality of pre-selected points;

(6) verifying that the measured data fall within pre-selected limits; and

(7) generating a set of calibration coefficients to establish the center of gravity at a plurality of positions encountered during operation of the mobility device, the calibration coefficients based on the verified measured data.

16 . The method as in claim 15 further comprising storing the verified measured data in non-volatile memory.

17 . The method as in claim 11 further comprising issuing commands to adjust stability of the mobility device based at least on a change in the load.

18 . The method as in claim 11 further comprising:

measuring the load on the mobility device including:

lifting the seat and the load while measuring a first torque required to lift the seat and the load; and

estimating a second torque, based on the motor current, required to lift the load.

19 . The method as in claim 11 further comprising computing the weight estimate based at least on a height of the seat, the seat motor current, and a pre-selected threshold value associated with the seat motor.

Assignments (1)

Continuity (5)

References Cited (400)