Prosthetic, orthotic or exoskeleton device

Abstract

A time-dependent decay behavior is incorporated into one or more joint actuator control parameters during operation of a lower-extremity, prosthetic, orthotic or exoskeleton device. These parameters may include joint equilibrium, joint impedance (e.g., stiffness, damping) and/or joint torque components (e.g., gain, exponent). The decay behavior may be exponential, linear, piecewise, or may conform to any other suitable function. Embodiments presented herein are used in a control system that emulates biological muscle-tendon reflex response providing for a natural walking experience. Further, joint impedance may depend on an angular rate of the joint. Such a relationship between angular rate and joint impedance may assist a wearer in carrying out certain activities, such as standing up and ascending a ladder.

What is claimed is: 
     
         1 . A prosthesis, orthosis or exoskeleton device, comprising:
 a joint constructed and arranged to permit flexion and extension between a proximal member and a distal member;   a motorized actuator configured to apply at least one of a joint impedance referenced to a joint equilibrium or a joint torque;   a sensor configured to detect a characteristic of the device; and   a controller configured to modulate a parameter comprising at least one of the joint equilibrium, the joint impedance and the joint torque according to the detected characteristic, the modulated parameter exhibiting time-dependent decay behavior.   
     
     
         2 . The device of  claim 1 , wherein the detected characteristic comprises at least one of a phase and a change in a phase of joint motion in a repetitive cycle, each occurrence of the cycle comprising a plurality of phases; and
 the time-dependent decay behavior comprises a decaying time response to the modulated parameter according to at least one of the detected phase and the detected change in phase of joint motion, wherein a duration of the time-dependent decay behavior comprises at least one phase of the one cycle.   
     
     
         3 . The device of  claim 1 , wherein the joint torque comprises a positive force-feedback component comprising at least one of a gain and an exponent as applied to the joint torque. 
     
     
         4 . The apparatus of  claim 3 , wherein the at least one of the gain or the exponent are modulated as a function of at least one of a proximal member angular rate, a distal member angular rate and a torque rate. 
     
     
         5 . The device of  claim 4 , wherein the positive force feedback component comprises a function of a rate of change of at least one of a joint torque and an actuator torque. 
     
     
         6 . The device of  claim 1 , wherein the modulated parameter comprises at least one of a proximal member angular rate, a distal member angular rate and at least one of a joint torque rate and an actuator torque rate. 
     
     
         7 . The device of  claim 1 , wherein the time-dependent decay behavior comprises an exponential decay. 
     
     
         8 . The device of  claim 1 , wherein the sensor is configured to detect a joint position and the controller is configured to modulate the joint equilibrium to converge with the detected joint position. 
     
     
         9 . The apparatus of  claim 1 , wherein the device is a knee prosthesis, orthosis or exoskeleton. 
     
     
         10 . The device of  claim 1 , wherein the joint impedance includes at least one of a stiffness and damping. 
     
     
         11 . The device of  claim 10 , wherein the stiffness comprises an early stance flexion stiffness. 
     
     
         12 . The apparatus of  claim 10 , wherein the stiffness comprises a knee flexion stiffness that is a function of knee joint angular rate. 
     
     
         13 . The apparatus of  claim 1 , wherein the joint torque is in a late stance and is a positive force feedback component. 
     
     
         14 . The apparatus of  claim 13 , wherein the positive force feedback component modulates a positive force feedback as a function of a rate of change of the joint torque. 
     
     
         15 . The apparatus of  claim 14 , wherein the at least one of the gain or the exponent are modulated according to at least one of the detected phase and a change in the detected phase. 
     
     
         16 . A method comprising:
 actuating the motorized actuator of  claim 1  to apply the at least one of the joint impedance or the joint torque; and   applying the controller to modulate the parameter.   
     
     
         17 . The method of  claim 16 , wherein the detected characteristic comprises at least one of a phase and a change in a phase of joint motion in a repetitive cycle, each occurrence of the cycle comprising a plurality of phases; and
 the time-dependent decay behavior comprises a decaying time response to the modulated parameter according to at least one of the detected phase and the detected change in phase of joint motion, wherein a duration of the time-dependent decay behavior comprises at least one phase of the one cycle.   
     
     
         18 . The method of  claim 16 , wherein the joint torque comprises a positive force-feedback component comprising at least one of a gain and an exponent as applied to the joint torque. 
     
     
         19 . A controller for a prosthesis, orthosis or exoskeleton device comprising a joint constructed and arranged to permit flexion and extension between a proximal member and a distal member, a motorized actuator configured to apply at least one of a joint impedance referenced to a joint equilibrium or a joint torque, and a sensor configured to detect a characteristic of the device, the controller comprising
 a processor; and   a non-transitory computer-readable medium storing instructions that, when executed by the processor, configure the processor to:
 modulate a parameter comprising at least one of the joint equilibrium, the joint impedance and the joint torque according to the detected characteristic, the modulated parameter exhibiting time-dependent decay behavior. 
   
     
     
         20 . The controller of  claim 19 , wherein the detected characteristic comprises at least one of a phase and a change in a phase of joint motion in a repetitive cycle, each occurrence of the cycle comprising a plurality of phases; and
 the time-dependent decay behavior comprises a decaying time response to the modulated parameter according to at least one of the detected phase and the detected change in phase of joint motion, wherein a duration of the time-dependent decay behavior comprises at least one phase of the one cycle.