Implementing a stand-up sequence using a lower-extremity prosthesis or orthosis

Abstract

Knee orthoses or prostheses can be used to automatically when it is appropriate to initiate a stand-up sequence based on the position of the person's knee with respect to the person's ankle while the person is in a seated position. When the knee is moved to position that is forward of the ankle, at least one actuator of the orthosis or prosthesis is actuated to help raise the person from the seated position to a standing position.

1 . An active orthotic or prosthetic apparatus comprising:
 a thigh member;   a lower leg member;   a knee joint for connecting the thigh member to the lower leg member;   a rotary motor comprising a motor shaft output;   a motor drive transmission assembly coupled to the motor shaft output;   a drive transmission assembly coupled to the output of the motor drive transmission, with an output of the drive transmission assembly coupled to the lower leg member for applying torque to the knee joint to rotate the lower leg member with respect to the thigh member;   at least one sensor having at least one output from which a position of the knee joint with respect to an ankle joint can be determined while the wearer of the apparatus is in a seated position; and   a controller that determines when the knee joint is moved to position that is forward of the ankle joint based on the least one output of the at least one sensor, and in response to said determination, controls the rotary motor so as to modulate impedance, position, or torque of the knee joint to help raise the person from the seated position to a standing position.   
     
     
         2 . The apparatus of  claim 1 , wherein the at least one sensor comprises an inertial sensor that measures a gravity vector in relation to a thigh coordinate system. 
     
     
         3 . The apparatus of  claim 1 , wherein the at least one sensor detects a rotation angle of the lower leg in relation to the thigh. 
     
     
         4 . The apparatus of  claim 1 , wherein the controller is programmed to maintain a low joint impedance in response to a determination that the wearer is in a sitting position. 
     
     
         5 . The apparatus of  claim 1 , wherein the controller is programmed to verify the wearer's desire to stand by tentatively initiating a stand-up routine. 
     
     
         6 . The apparatus of  claim 5 , wherein the controller is programmed to proceed with the stand-up routine if positive feedback is received and to abort the stand-up routine if positive feedback is not received. 
     
     
         7 . The apparatus of  claim 1 , wherein the controller controls the rotary motor to help raise the person from the seated position to a standing position by increasing torque gradually in accordance with the estimated upward and forward velocity of the hip joint. 
     
     
         8 . The apparatus of  claim 7 , wherein the controller controls the rotary motor so that as the patient's approaches the standing state, restorative torque is applied to assist the wearer in achieving balance while in the standing state. 
     
     
         9 . The apparatus of  claim 1 , further comprising at least one pressure sensor configured to measure a force being applied to the wearer's foot. 
     
     
         10 . The apparatus of  claim 1 , wherein the controller controls the rotary motor to help raise the person from the seated position to a standing position by increasing knee torque in accordance with a measured electromyographic signals from at least one of a knee muscle and a hip muscle. 
     
     
         11 . A method of controlling a knee orthosis or prosthesis having at least one actuator, the knee orthosis or prosthesis being worn by a person, the method comprising the steps of:
 detecting the position of the person's knee with respect to the person's ankle while the person is in a seated position;   determining when the knee is moved to position that is forward of the ankle based on a result of the detecting step, and generating an output indicative thereof; and   actuating, in response to the output, at least one actuator of the knee orthosis or prosthesis to help raise the person from the seated position to a standing position.   
     
     
         12 . The method of  claim 11 , further comprising the step of measuring a gravity vector in relation to a thigh coordinate system. 
     
     
         13 . The method of  claim 11 , further comprising the step of detecting a rotation angle of the person's lower leg in relation to the person's thigh. 
     
     
         14 . The method of  claim 11 , further comprising the step of maintaining a low joint impedance in response to a determination that the person is in a sitting position. 
     
     
         15 . The method of  claim 11 , further comprising the step of verifying the person's desire to stand by tentatively initiating a stand-up routine. 
     
     
         16 . The method of  claim 15 , further comprising the steps of:
 determining if positive feedback is received; and   proceeding with the stand-up routine if it is determined in the determining step that positive feedback is received; and   aborting the stand-up routine if it is determined in the determining step that positive feedback is not received.   
     
     
         17 . The method of  claim 11 , further comprising the step of increasing torque in accordance with the estimated upward and forward velocity of a hip joint. 
     
     
         18 . The method of  claim 17 , further comprising the step of applying restorative torque applied to assist the person in achieving balance while in the standing state. 
     
     
         19 . The method of  claim 11 , further comprising the step of measuring a force being applied to the person's foot. 
     
     
         20 . The method of  claim 11 , further comprising the step of increasing knee torque in accordance with a measured electromyographic signals from at least one of a knee muscle and a hip muscle.