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.

We claim: 
     
         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.