Calibration of electrode-to-muscle mapping for functional electrical stimulation

Patent metadata

Field	Value
Publication number	US-11266833-B2
Application number	US-202117320604-A
Country	US
Kind code	B2
Filing date	May 14, 2021
Priority date	May 14, 2020
Publication date	Mar 8, 2022
Grant date	Mar 8, 2022

Abstract

A functional electrical stimulation (FES) device includes electrodes arranged to apply functional electrical stimulation to a body part of the user. FES stimulation is performed by: receiving values of a set of user metrics for the user; receiving a target position of the body part represented as values for a set of body part position measurements; determining a user-specific energization pattern for producing the target position based on the received target position and the received values of the set of user metrics for the user; and energizing the electrodes of the FES device in accordance with the determined user-specific energization pattern. The determination may utilize an FES calibration database with records having fields containing: values of the set of user metrics for reference users; energization patterns; and values of the set of body part position metrics for positions assumed by the body part in response to applying the energization patterns.

First claim

The invention claimed is:

1. A functional electrical stimulation (FES) system comprising:
an FES device configured for connection with an associated body part and including electrodes arranged to apply functional electrical stimulation to the associated body part and further including sensors to measure a position of the associated body part; and
an electronic processor programmed to perform an iterative calibration method to determine a calibrated electrode energization pattern for producing a movement of the associated body part, an iteration of the iterative calibration method including:
for each proposal of a current pool of proposals, applying the proposal comprising an electrode energization pattern to the electrodes of the FES device and receiving sensor readings from the sensors of the FES device with the associated body part positioned by the applying of the proposal and generating an error metric for the proposal with respect to the movement using an error function corresponding to the movement that depends on the sensor readings, and
generating an updated pool of proposals for a next iteration of the iterative calibration method by modifying the proposals of the current pool of proposals based on the generated error metrics,

wherein the iterative calibration method selects, based on the error metrics, the calibrated electrode energization pattern for producing the movement from the proposals applied during one or more iterations of the iterative calibration method.

2. The FES system of claim 1 wherein the applying of the proposal includes:
ramping up an amplitude of the electrode energization pattern applied to the electrodes of the FES device;
stopping the ramping in response to the first to occur of (i) the amplitude reaching a maximum amplitude or (ii) receiving a user-generated stop signal;
determining whether the ramping produced pain based on the user-generated stop signal; and
discarding the proposal from the current pool of proposals if the determination is that the ramping produced pain.

3. The FES system of claim 1 wherein the error function corresponding to the movement comprises a weighted sum of squares (WSOS) where:

WSOS
=

∑

i
=
1

S

⁢

w
i

⁡

(

T
i

-

R
i

)

2

where s=1, . . . , S indexes the sensor readings, R i is the i th sensor reading, T i is a target value of the i th sensor reading for the movement, and w i is a weight assigned to the i th sensor reading for the movement.

4. The FES system of claim 1 wherein the iterative calibration method further comprises, prior to performing a first iteration, initializing the current pool of proposals for the first iteration using a priori information from a previous execution of the iterative calibration method.

5. The FES system of claim 1 wherein the iterative calibration method further comprises, prior to performing a first iteration, initializing the current pool of proposals for the first iteration by performing at least one sweep of cathodic and anodic regions of interest (ROIs) and selecting the current pool of proposals from the at least one sweep.

6. The FES system of claim 1 wherein the iterative calibration method is performed to determine a plurality of calibrated electrode energization patterns for producing a corresponding plurality of movements of the associated body part, and in the iteration:
the applying and receiving of the sensor readings is performed one time for each proposal of the current pool of proposals, and
the generating of the error metric includes generating an error metric for the proposal with respect to each movement of the plurality of movements using an error function corresponding to the movement that is functionally dependent on the sensor readings, and
the generating of the updated pool of proposals for the next iteration comprises (i) for each movement of the plurality of movements, generating a movement-specific pool of proposals by modifying the proposals of the current pool of proposals based on the generated error metrics for the movement, and (ii) combining the movement-specific pools of proposals for the plurality of movements to generate the updated pool of proposals for the next iteration.

7. The FES system of claim 1 wherein:
the proposal comprising the electrode energization pattern is represented as at least one parameterized distribution over a group of electrodes, and
the modifying of the proposals of the current pool of proposals based on the generated error metrics comprises modifying values of the parameters of the at least one parameterized distribution.

8. The FES system of claim 1 wherein the generating of the updated pool of proposals for the next iteration comprises modifying the proposals of the current pool of proposals based on the generated error metrics using a differential evolution (DE) algorithm.

9. The FES system of claim 1 wherein the generating of the updated pool of proposals for the next iteration comprises performing Bayesian optimization of the proposals of the current pool of proposals.

10. The FES system of claim 1 wherein the electronic processor is further programmed to perform an assistance method including:
receiving or generating a command signal to perform the movement and,
in response to the received or generated command signal, applying the calibrated electrode energization pattern for producing the movement to the electrodes of the FES device to produce the movement of the associated body part.

11. A functional electrical stimulation (FES) system comprising:
an FES device configured for connection with an associated body part of a user and including electrodes arranged to apply functional electrical stimulation to the associated body part of the user; and
an electronic processor programmed to perform FES stimulation by operations including:
receiving values of a set of user metrics for the user;
receiving a target position of the associated body part represented as values for a set of body part position measurements;
determining a user-specific energization pattern for producing the target position of the associated body part based on the received target position of the associated body part and the received values of the set of user metrics for the user; and
energizing the electrodes of the FES device in accordance with the determined user-specific energization pattern.

12. The FES system of claim 11 wherein the determining of the user-specific energization pattern includes:
determining the user-specific energization pattern based on a comparison of (i) the received target movement and the received values of the set of user metrics for the user and (ii) records stored in an FES calibration database;
wherein each record of the FES calibration database

Assignees

• Battelle Memorial Institute

Inventors

• Friedenberg David A
• Chen Po-Hsu
• Colachis Samuel
• Annetta Nicholas
• Boyd Douglas E
• Dunlap Collin
• Baumgart Ian W
• Bresler Herbert S

Classifications

• A61N1/36003 Primary

  of motor muscles, e.g. for walking assistance · CPC title

• A61N1/025

  Digital circuitry features of electrotherapy devices, e.g. memory, clocks, processors · CPC title

• A61B5/395

  Details of stimulation, e.g. nerve stimulation to elicit EMG response · CPC title

• A61N1/36031

  using physiological parameters for adjustment · CPC title

• G16H20/30

  relating to physical therapies or activities, e.g. physiotherapy, acupressure or exercising · CPC title