WIRELESS AND RETROFITTABLE IN-SHOE SYSTEM FOR REAL-TIME ESTIMATION OF KINEMATIC AND KINETIC GAIT PARAMETERS

Abstract

A quantitative gait training and/or analysis system includes one or more footwear modules that may include a piezoresistive sensor, an inertial sensor and an independent logic unit. The footwear module functions to permit the extraction of gait kinematics and evaluation thereof in real time, or data may be stored for later reduction and analysis. Embodiments relating to calibration-based estimation of kinematic gait parameters are described.

Claims

1. A gait measurement system, comprising: at least one insole module for placement in a shoe of a user, each of said at least one insole module including a piezoresistive sensor, an inertial sensor, a logic unit communicatively coupled to said piezoresistive sensor and to said inertial sensor, and a transmission unit; and a computing unit communicatively coupled to said inertial sensor and said piezoresistive sensor via said transmission unit.

2. The gait measurement system of claim 1, wherein said piezoresistive sensor includes a plurality of pressure-sensing cells.

3. The gait measurement system of claim 2, wherein said plurality of pressure-sensing cells includes eight of said cells.

4. The gait measurement system of claim 2, wherein at least some of said plurality of pressure-sensing cells are located beneath a user's calcaneous, a user's lateral arch, a head of a user's first metatarsal, a head of a user's third metatarsal, a head of a user's fifth metatarsal, a user's hallux and a user's toes.

5. The gait measurement system of claim 1, wherein each of said at least one insole module is adapted to be retrofitted to a shoe of a user.

6. The gait measurement system of claim 1, wherein said inertial sensor has nine-degrees of freedom.

7. The gait measurement system of claim 1, wherein said inertial sensor is located along a portion of said at least one insole module corresponding to a midline of a user's foot.

8. The gait measurement system of claim 1, wherein each of said at least one insole module further comprises feedback means for providing vibro-tactile feedback to a user.

9. The gait measurement system of claim 1, wherein said logic unit is configured to sample data at 500 Hertz.

10. The gait measurement system of claim 1, wherein said system is configured to estimate center of pressure and/or dynamic margin of stability.

11. The gait measurement system of claim 1, wherein said system is adapted to measure inter-limb parameters.

12. The gait measurement system of claim 1, wherein said system is adapted to measure one or more gait parameters selected from the group consisting of stride length, foot-ground clearance, foot trajectory, cadence, double support time, single support time, walking speed, center of pressure, and margin of stability.

13. The gait measurement system of claim 12, wherein said computing unit is further adapted to generate dynamic plantar pressure maps and/or center of pressure trajectories.

14. The gait measurement system of claim 1, wherein said computing unit is adapted to classify activities of daily living.

15. The gait measurement system of claim 1, wherein said system is adapted to cooperate with a mobile device having GPS in order to realize a portable navigation system.

16. The gait measurement system of claim 1, wherein said system is adapted to remotely monitor and administer walking and/or balance exercises.

17. The gait measurement system of claim 1, wherein said system is adapted to provide gait and/or balance rehabilitation.

18. A method for calibrating a gait measurement system, comprising the steps of: i) providing an instrumented insole having a plurality of pressure-sensing cells; ii) exerting known, uniform pressure on said instrumented insole; iii) recording a respective output for each of said pressure-sensing cells in response to pressure exerted on said instrumented insole during the performance of step (ii); iv) applying a plurality of fitting functions to said respective output of each of said pressure-sensing cells, thereby obtaining a plurality of respective model data; and v) applying cross validation to said respective model data to obtain a calibration model for each of said pressure-sensing cells.

19. A method for calibrating a gait measurement system, comprising the steps of: i) providing an instrumented insole and a reference measuring apparatus; ii) recording a first data set from said instrumented insole and a second data set from said reference measuring apparatus; iii) computing center of pressure trajectories from said first and said second data sets; iv) validating the accuracy of said center of pressure trajectories using one or more regression models; and v) calibrating said instrumented insole via said first and said second data sets.

Description

BRIEF DESCRIPTION OF FIGURES

[0020] For a more complete understanding of the present disclosure, reference is made to the following drawings, in which:

[0021] FIG. 1 is a schematic illustration of the first step of a novel two-step calibration approach for the CoP, illustrating a static calibration framework for multi-cell pressure insoles; and

[0022] FIG. 2 is a schematic illustration of the second step of a novel two-step calibration approach for the CoP, illustrating a dynamic calibration framework for CoP trajectories.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0023] In an embodiment, the present invention is a device comprising two insole modules and a data logger. Each insole module is wireless, having a transmission unit, as well as the ability to accurately measure kinematic and kinetic gait parameters of a user in a variety of dynamic tasks (e.g., walking, running, negotiating stairs, etc.), both outdoor and indoor. In an embodiment, all the data are collected at 500 Hz and sent wirelessly to a battery-powered single-board computer (or mobile device) running a data-logger. In an embodiment, the single-board computer fits inside a running belt that can be worn by the user or can be optionally located offboard within a 30-meter range from the user.

[0024] In an embodiment, each insole module consists of an eight-cell piezoresistive sensor, a nine degree-of-freedom inertial sensor, and a custom-made logic unit. The pressure sensors are located, for instance, underneath the calcaneous, the lateral arch, the head of the first, third and fifth metatarsals, the hallux, and the toes, while the inertial sensor is placed, for instance, along the midline of the foot.

[0025] In an embodiment, the logic unit includes a microcontroller interfaced with the multi-cell pressure sensor through an eight-channel multiplexer, while communicating with the inertial sensor through a serial connection. In an embodiment, all the data are sampled at 500 Hz and sent through UDP over WLAN to the single-board computer by means of a Wi-Fi module. The logic unit, which can be housed in a plastic enclosure, is powered by, for instance, a small 400 mAh Li-po battery through a step-up voltage regulator.

[0026] In an embodiment, the single-board computer runs a Linux distribution with a real-time kernel operating in headless mode. A miniature Wi-Fi router can be connected to the computer, serving as an access point. In use, for example, the computer synchronizes the data incoming from the insole modules and writes them to a micro-SD card. The same data can also be streamed at a lower sample rate (50 Hz) to an easy-to-use user interface running on the user's laptop or mobile phone, whereby the interface allows the user to control the device remotely and to visualize measured data.

[0027] Other features, attributes and exemplary embodiments of the present invention are disclosed and illustrated in the publication by Huanghe Zhang et al., titled “Estimating CoP Trajectories and Kinematic Gait Parameters in Walking and Running Using Instrumented Insoles,” IEEE Robotics and Automation Letters, Vol. 2, No. 4, Oct. 2017, pp. 2159-2165, and in the publication by Huanghe Zhang et al., titled “Regression Models for Estimating Kinematic Gait Parameters with Instrumented Footwear,” IEEE International Conference on Biomedical Robotics and Biomechatronics, Aug. 2018,both publications being incorporated by reference herein in their entireties and therefore constituting part of the present application. In addition to the incorporation by reference immediately above, it is noted that the former publication identified above was attached as

[0028] Exhibit B in the related provisional U.S. patent application referenced above and incorporated by reference herein. With regard to the latter publication identified above, an earlier, unpublished version was attached as Exhibit C to the aforementioned provisional U.S. patent application.

[0029] It will be understood that the embodiments described in the foregoing specification and claims, as well those described in the various documents incorporated by reference herein, are merely exemplary and that a person skilled in the art may make many variations and modifications without departing from the spirit and scope of the present invention.