Prosthetic, orthotic or exoskeleton device
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 Reflex Parameter Modulation 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.
1. A prosthesis, orthosis or exoskeleton apparatus comprising:
a proximal member;
a distal member;
a joint connecting the proximal and distal members, the joint adapted to permit flexion and extension between the proximal and distal members;
a motorized actuator configured to apply a joint torque to the joint;
a walking speed sensor configured to output a measurement from which a walking speed is derived; and
a controller programmed with instructions that, when executed, cause the controller to modulate the joint torque applied by the motorized actuator, the modulation comprising:
accessing a first torque response configured to be applied at a first walking speed;
accessing a second torque response configured to be applied at a second walking speed, wherein the first walking speed is slower relative to the second walking speed;
deriving the walking speed from the measurement of the walking speed sensor;
blending the first torque response and the second torque response based on the derived walking speed to determine a blended torque response; and
applying the blended torque response with the motorized actuator.
2. The apparatus of claim 1 , wherein the first torque response and the second torque response are blended according to a linear interpolation based upon the derived walking speed.
3. The apparatus of claim 1 , wherein the first torque response and the second torque response are blended according to a nonlinear interpolation based upon the derived walking speed.
4. The apparatus of claim 1 , wherein the first torque response and the second torque response are blended according to a distance between the walking speed derived from the measurement of the walking speed sensor, the first walking speed, and the second walking speed.
5. The apparatus of claim 1 , wherein the joint torque comprises a positive force-feedback component that comprises a gain and an exponent as applied to the joint torque.
6. The apparatus of claim 5 , wherein the gain and the exponent take on values that are independent of each other.
7. The apparatus of claim 5 , wherein the first torque response applies a slow-speed torque model that defines a slow-speed gain and a slow-speed exponent, and the second torque response applies a fast-speed torque model that applies a fast-speed gain and a fast-speed exponent.
8. The apparatus of claim 5 , wherein the first torque response and the second torque response apply a single torque model with the gain and exponent being interpolated based on the walking speed derived from the measurement of the walking speed sensor.
9. The apparatus of claim 1 , further comprising a phase sensor configured to detect 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, wherein the motorized actuator is configured to apply the joint torque during a powered plantarflexion phase of locomotion.
10. The apparatus of claim 1 , wherein the controller is further configured to access additional torque models and blend the additional torque models based on the walking speed derived from the measurement of the walking speed sensor.
11. A method applied to a prosthesis, orthosis or exoskeleton apparatus comprising a proximal member, a distal member, a joint connecting the proximal and distal members, the joint adapted to permit flexion and extension between the proximal and distal members, a motorized actuator configured to apply a joint torque to the joint, a walking speed sensor configured to output a measurement from which a walking speed is derived, and a controller, the method comprising:
accessing a first torque response configured to be applied at a first walking speed;
accessing a second torque response configured to be applied at a second walking speed, wherein the first walking speed is slower relative to the second walking speed;
deriving the walking speed from the measurement of the walking speed sensor;
blending the first torque response and the second torque response based on the derived walking speed to determine a blended torque response; and
applying the blended torque response with the motorized actuator.
12. The method of claim 11 , wherein the first torque response and the second torque response are blended according to a linear interpolation based upon the derived walking speed.
13. The method of claim 11 , wherein the first torque response and the second torque response are blended according to a nonlinear interpolation based upon the derived walking speed.
14. The method of claim 11 , wherein the first torque response and the second torque response are blended according to a distance between the walking speed derived from the measurement of the walking speed sensor, the first walking speed, and the second walking speed.
15. The method of claim 11 , wherein the joint torque comprises a positive force-feedback component that comprises a gain and an exponent as applied to the joint torque.
16. The method of claim 15 , wherein the gain and the exponent take on values that are independent of each other.
17. The method of claim 15 , wherein the first torque response applies a slow-speed torque model that defines a slow-speed gain and a slow-speed exponent, and the second torque response applies a fast-speed torque model that applies a fast-speed gain and a fast-speed exponent.
18. The method of claim 15 , wherein the first torque response and the second torque response apply a single torque model with the gain and exponent being interpolated based on the walking speed derived from the measurement of the walking speed sensor.
19. The method of claim 11 , further comprising a phase sensor configured to detect 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, wherein the motorized actuator is configured to apply the joint torque during a powered plantarflexion phase of locomotion.
20. The method of claim 11 , wherein the controller is further configured to access additional torque models and blend the additional torque models based on the walking speed derived from the measurement of the walking speed sensor.
21. A non-transitory computer-readable storage medium, the computer-readable storage medium including instructions that when executed by a controller, cause the controller to modulate a torque applied to a prosthesis, orthosis or exoskeleton apparatus comprising a proximal member, a distal member, a joint connecting the proximal and distal members, the joint adapted to permit flexion and extension between the proximal and distal members, a motorized actuator configured to apply a joint torque to the joint, and a walking speed sensor configured to output a measurement from which a walking speed is derived, the instructions comprising instructions to:
access a first torque response configured to be applied at a first walking speed;
access a second torque response configured to be applied at a second walking speed wherein the first walking speed is slower relative to the second walking speed;
derive the walking speed from the measurement of the walking speed sensor;
blend the first torque response and the second torque response based on the derived walking speed to determine a blended torque response; and
apply the blended torque response with the motorized actuator.
22. The computer-readable storage medium of claim 21 , wherein the first torque response and the second torque response are blended according to a linear interpolation based upon the derived walking speed.
23. The computer-readable storage medium of claim 21 , wherein the first torque response and the second torque response are blended according to a nonlinear interpolation based upon the derived walking speed.
24. The computer-readable storage medium of claim 21 , wherein the first torque response and the second torque response are blended according to a distance between the walking speed derived from the measurement of the walking speed sensor, the first relatively slow walking speed, and the second walking speed.
25. The computer-readable storage medium of claim 21 , wherein the joint torque comprises a positive force-feedback component that comprises a gain and an exponent as applied to the joint torque.
26. The computer-readable storage medium of claim 25 , wherein the gain and the exponent take on values that are independent of each other.
27. The computer-readable storage medium of claim 25 , wherein the first torque response applies a slow-speed torque model that defines a slow-speed gain and a slow-speed exponent, and the second torque response applies a fast-speed torque model that applies a fast-speed gain and a fast-speed exponent.
28. The computer-readable storage medium of claim 25 , wherein the first torque response and the second torque response apply a single torque model with the gain and exponent being interpolated based on the walking speed derived from the measurement of the walking speed sensor.
29. The computer-readable storage medium of claim 21 , wherein the instructions further configure the apparatus to detect 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 apply the joint torque during a powered plantarflexion phase of locomotion.
30. The computer-readable storage medium of claim 21 , wherein the controller is further configured to access additional torque models and blend the additional torque models based on the walking speed derived from the measurement of the walking speed sensor.