Prosthetic sensing systems and methods

Abstract

Systems and methods are disclosed for sensing forces, moments, temperature, inclination, acceleration and other parameters associated with prosthetic limbs. The system is capable of measuring forces in three designated axes, and moments about the same designated axes, for a total of six possible degrees of freedom. The system can be readily fitted onto a conventional prosthetic limb with no, or relatively minor, modification thereto. A plurality of sensor arrays are disposed on a support member, each array including a plurality of strain gauge sensors, each sensor outputting an electrical signal responsive to loading imposed on the support member through the prosthetic limb. Electronic circuitry in communication with the gauges is operative to receive the electrical signals from the strain gauges and provide a signal useful in the form, fit or function of the prosthetic limb.

1 . A sensing system for use with a prosthetic limb, comprising:
 a support member having a length axis configured for attachment to a prosthetic limb;   a plurality of sensor arrays disposed on the support member, each array including a plurality of strain gauge sensors, each sensor outputting an electrical signal responsive to loading imposed on the support member through the prosthetic limb;   the plurality of sensor arrays including at least one array having a sensor aligned with the length axis of the support member; and   electronic circuitry in communication with the gauges, the electronic circuitry being operative to receive the electrical signals from the strain gauges and provide a signal useful in the form, fit or function of the prosthetic limb.   
     
     
         2 . The system of  claim 1 , wherein each strain gauge array includes a plurality of strain gauge sensors oriented to sense loads along three independent axes and the moments associated therewith so as to determine all six subcomponents needed to fully describe a load applied to the prosthetic limb. 
     
     
         3 . The system of  claim 1 , further including an array having a gauge oriented along the length axis of the support member and a pair of gauges oriented at angles on either side of the axially oriented gauge. 
     
     
         4 . The system of  claim 3 , wherein the pair of strain gauges are oriented at 45 degree angles relative to the axially oriented gauge. 
     
     
         5 . The system of  claim 1 , wherein the support member is a rigid tube having a first end configured for attachment to the socket of a prosthetic limb, and a second end configured for attachment to a pylon of a prosthetic limb. 
     
     
         6 . The system of  claim 1 , wherein:
 the support member is configured for attachment to a prosthetic leg; and   the placement of the support member is:   between the foot and a pylon, or   between the pylon and a knee device, or above a knee device, or   between a knee device and an above-the-knee socket.   
     
     
         7 . The system of  claim 1 , wherein the electronic circuitry is configured such that the strain gauges generate positive and negative (signed) voltages. 
     
     
         8 . The system of  claim 7 , wherein the electronic circuitry is operative to determine moments and shear forces based upon the signed voltages generated by the strain gauges. 
     
     
         9 . The system of  claim 7 , wherein the electronic circuitry is operative to compensate for off-center loading using the signed voltages. 
     
     
         10 . The system of  claim 1 , further including analog or digital switches operative to activate the strain gauges as necessary to conserve power or reduce heat generation. 
     
     
         11 . The system of  claim 1 , wherein the electronic circuitry includes an analog multiplexer interconnecting the strain gauges to a common instrumentation amplifier such that the gains of the strain gages are substantially equalized. 
     
     
         12 . The system of  claim 1 , further including:
 an inclinometer and accelerometer; and   wherein the signal provided by the electronic circuitry is used to analyze the gait of a user.   
     
     
         13 . The system of  claim 1 , further including:
 a pair of inclinometers, one disposed on either side of an articulating joint; and   wherein the electronic circuitry is operative to receive signals from the inclinometers and output data approximating a goniometer.   
     
     
         14 . The system of  claim 13 , wherein the inclinometers are disposed on either side of an ankle joint. 
     
     
         15 . The system of  claim 1 , further including a data collection module for receiving the signal from the electronic circuitry. 
     
     
         16 . The system of  claim 15 , wherein the module receives the signal from the electronic circuitry through a wired or wireless connection. 
     
     
         17 . The system of  claim 15 , further including:
 an unaffected limb electronics package (ULEP) including an inclinometer and accelerometer; and   wherein the module for collecting data is further operative to receive data from the inclinometer and accelerometer of the ULEP to analyze the gait of a user.   
     
     
         18 . The system of  claim 15 , further including:
 an unaffected limb electronics package (ULEP) including a pair of inclinometers, one disposed on either side of an articulating joint; and   wherein the module for collecting data is further operative to output data approximating that of a goniometer associated with the unaffected limb.   
     
     
         19 . The system of  claim 1 , wherein the electronic circuitry is powered by a generator associated with said prosthetic limb. 
     
     
         20 . The system of  claim 19 , wherein the generator is a piezoelectric generator or a moving magnet generator. 
     
     
         21 . The system of  claim 1 , wherein the electronic circuitry operates on an intermittent basis to conserve power. 
     
     
         22 . The system of  claim 1 , further including a motion detector operative to activate the electronic circuitry when motion is detected. 
     
     
         23 . The system of  claim 1 , wherein the data provided by the electronic circuitry is operative to control a component of the prosthetic limb. 
     
     
         24 . The system of  claim 1 , wherein the data provided by the electronic circuitry is operative to provide an alarm indicating malfunction of the prosthetic limb. 
     
     
         25 . The system of  claim 1 , wherein the support member is flexible. 
     
     
         26 . The system of  claim 25 , wherein the support member comprises a sheet of flexible polymeric material which is affixable to the prosthetic limb. 
     
     
         27 . The system of  claim 1 , wherein the prosthetic limb is a leg or an arm. 
     
     
         28 . A method of analyzing a user's gait, said method comprising the steps of:
 providing the system of  claim 1 ;   disposing the system on a prosthetic leg or arm worn by the user;   having the user walk; and   analyzing the data provided by the electronic circuitry.   
     
     
         29 . A method of controlling the operation of a prosthetic limb, comprising the steps of:
 providing a prosthetic leg or arm having an electronically controllable component thereupon;   providing the system of  claim 1 ;   affixing the system to the prosthetic leg or arm worn by a user;   having the user walk; and   using the data provided by the electronic circuitry to control the operation of the electronically controllable component.