Hybrid Terrain-Adaptive Lower-Extremity Systems

• US 20100179668A1
• Filed: 09/01/2009
• Published: 07/15/2010
• Est. Priority Date: 09/04/2008
• Status: Active Grant

• Current Assignee: Otto Bock HealthCare LP (Nader Holding GmbH & Co. KG)
• Original Assignee: iWalk Incorporated (Ottobock SE & Co. KGaA)
• Inventors: Thompson, Gregory K., Barnhart, Christopher E., Margolin, Alexander S., Size, Kristin J., Dalrymple, Timothy M., Murray, David W., Casler, Rick, Kowalczyk, Matthew T., Herr, Hugh M., Nook, Christopher M., Spaller, Robert W., Kessler, Seth S.
• Granted Patent: US 9,345,592 B2
• Time in Patent Office: Days
• US Class Current: 623/51
• CPC Class Codes: A61F 2/60 Artificial legs or feet or parts thereof
• CPC Class Codes: A61F 2/6607 Ankle joints
• CPC Class Codes: A61F 2/70 electrical
• CPC Class Codes: A61F 2/72 Bioelectric control, e.g. myoelectric
• CPC Class Codes: A61F 2002/5003 having damping means, e.g. shock absorbers for implantable joints A61F2002/30563
• CPC Class Codes: A61F 2002/5007 having elastic means different from springs, e.g. including an elastomeric insert elastic coating A61F2002/3007; springs A61F2002/5072; plate-like springs for feet A61F2002/6657
• CPC Class Codes: A61F 2002/5018 for adjusting angular orientation
• CPC Class Codes: A61F 2002/503 for adjusting elasticity, flexibility, spring rate or mechanical tension
• CPC Class Codes: A61F 2002/5033 for adjusting damping damping means A61F2002/5003
• CPC Class Codes: A61F 2002/5079 Leaf springs A61F2002/6657 takes precedence
• CPC Class Codes: A61F 2002/5087 Sound-damping or noise-reducing means
• CPC Class Codes: A61F 2002/6614 Feet
• CPC Class Codes: A61F 2002/6836 Gears specially adapted therefor, e.g. reduction gears
• CPC Class Codes: A61F 2002/701 operated by electrically controlled means, e.g. solenoids or torque motors
• CPC Class Codes: A61F 2002/704 computer-controlled, e.g. robotic control
• CPC Class Codes: A61F 2002/7625 for measuring angular position
• CPC Class Codes: A61F 2002/763 for measuring spatial position, e.g. global positioning system [GPS]
• CPC Class Codes: A61F 2002/7635 for measuring force, pressure or mechanical tension
• CPC Class Codes: A61F 2002/764 for measuring acceleration
• CPC Class Codes: A61F 2002/7645 for measuring torque, e.g. hinge or turning moment, moment of force
• CPC Class Codes: A61F 2002/7665 : for measuring temperatures
• CPC Class Codes: A61F 2005/0155 : with actuating means
• CPC Class Codes: A61F 2005/0169 : with damping means
• CPC Class Codes: A61H 1/0266 : Foot
• CPC Class Codes: A61H 2003/001 : on steps or stairways
• CPC Class Codes: A61H 3/00 : Appliances for aiding patients or disabled persons to walk about apparatus for helping babies to walk A47D13/04; orthopaedic devices for correcting deformities of, or supporting, limbs A61F5/0102; exercising apparatus for the feet or toes A63B23/10; stairways or ramps E04F11/00
• CPC Class Codes: B25J 9/0006 : Exoskeletons, i.e. resembling a human figure
• CPC Class Codes: G01L 5/0028 : Force sensors associated with force applying means G01L5/0052, G01L5/0057, G01L5/0061 take precedence
• CPC Class Codes: G01L 5/0061 : Force sensors associated with industrial machines or actuators for the specific machine or actuator involved see relevant class, e.g. F01, F04, F16, B66, E21
• CPC Class Codes: G01P 21/00 : Testing or calibrating of apparatus or devices covered by the preceding groups
• CPC Class Codes: H02K 7/06 : Means for converting reciprocating motion into rotary motion or vice versa
• CPC Class Codes: H02K 7/116 : with gears

Abstract

Hybrid terrain-adaptive lower-extremity apparatus and methods that perform in a variety of different situations by detecting the terrain that is being traversed, and adapting to the detected terrain. In some embodiments, the ability to control the apparatus for each of these situations builds upon five basic capabilities: (1) determining the activity being performed; (2) dynamically controlling the characteristics of the apparatus based on the activity that is being performed; (3) dynamically driving the apparatus based on the activity that is being performed; (4) determining terrain texture irregularities (e.g., how sticky is the terrain, how slippery is the terrain, is the terrain coarse or smooth, does the terrain have any obstructions, such as rocks) and (5) a mechanical design of the apparatus that can respond to the dynamic control and dynamic drive.

Claims

1. A low noise linear actuator, comprising:

a rotary motor comprising a motor shaft output; and

a screw transmission assembly comprising

a threaded shaft coupled to the motor shaft output, the threaded shaft comprising a hollowed out portion containing an acoustic damping material,

a nut assembly, wherein

the screw transmission assembly translates rotational motion of the motor shaft output to a linear motion of the nut assembly.

2. The linear actuator of claim 1, wherein the screw transmission assembly is a ball-screw transmission assembly and the nut assembly is a ball-nut assembly, wherein the ball-nut assembly further comprises a plurality of ball bearings and a plurality of ball tracks for holding the ball bearings and for recirculating the ball bearings in the ball bearing assembly.

3. The linear actuator of claim 2, comprising a pulley coupling the motor shaft output to the threaded shaft via a plurality of belts connected in parallel between the pulley and the threaded shaft of the ball-screw transmission assembly.

4. The linear actuator of claim 3, comprising a sensor that validates belt integrity during operation.

5. The linear actuator of claim 3, wherein the pulley is welded to the motor shaft output.

6. The linear actuator of claim 3, comprising a radial and thrust bearing coupling the plurality of belts to the threaded shaft to support loads applied by tension in the belts and the threaded shaft.

7. The linear actuator of claim 2, wherein the ball-screw transmission assembly comprises at least one seal for protecting the ball-screw transmission assembly from contaminants.

8. The linear actuator of claim 1, wherein the linear actuator is a component of a lower extremity prosthesis orthosis, or exoskeleton.

9. The linear actuator of claim 1, comprising a transmission that employs traction wheels that couple the motor shaft output to the threaded shaft of the ball-screw transmission assembly.

10. The linear actuator of claim 1, wherein the screw transmission assembly is a lead screw transmission assembly.

11. A linear actuator, comprising:

a rotary motor comprising a motor shaft output;

a motor drive transmission assembly coupled to the motor shaft output to translate rotational motion of the motor shaft output to a linear motion at an output of the motor drive transmission; and

at least one elastic element with bi-directional stiffness connected in series with the motor drive transmission assembly to store energy in tension and compression.

12. The linear actuator of claim 11, comprising a strain sensor coupled to the at least one elastic element for measuring strains in the at least one elastic element.

13. The linear actuator of claim 12, the at least one elastic element is a series or parallel elastic element coupled to the output of the motor drive transmission assembly.

14. The linear actuator of claim 13, comprising a controller for receiving measured strain signals for performing closed loop control of the linear actuator thrust force.

15. The linear actuator of claim 11, wherein the at least one elastic element is a substantially flat spring divided along a longitudinal axis of the spring minimizing out-of-plane moment applied by the spring to the output of the motor drive transmission assembly.

16. The linear actuator of claim 11, wherein the at least one elastic element is a series elastic strain element coupled to the output of the motor drive transmission assembly, and further comprising a sensor that measures motor position or position of the output of the motor drive transmission assembly, and at least one sensor that measures the output of the series elastic element, and signal processing electronics that estimates thrust force of the linear actuator for closed loop control of the linear actuator thrust force.

17. A lower-extremity prosthesis, orthosis or exoskeleton apparatus, comprising:

a foot member;

a lower leg member;

an ankle joint for connecting the foot member to the lower leg member;

a first actuator for applying torque to the ankle joint to rotate the foot member with respect to the lower leg member; and

at least one passive elastic members that is a non-compliant stop connected in parallel with the actuator between the lower leg member and the foot member, wherein the non-compliant stop stores little or no energy during dorsiflexion and limits further rotation of the ankle beyond a predefined angle during powered plantar flexion.

18. The apparatus of claim 17, comprising an angle adjustment mechanism for setting a pre-specified angle of the foot member relative to the lower leg member at which the non-compliant stop limits further rotation.

19. The apparatus of claim 18, wherein the angle adjustment mechanism comprises a screw adjustable component for setting the pre-specified angle.

20. The apparatus of claim 18, wherein the angle adjustment mechanism comprises an actuator for setting the pre-specified angle.

21. The apparatus of claim 20, wherein the actuator adjusts the pre-specified angle based on a property of the underlying terrain.

22. The apparatus of claim 21, wherein the property of the underlying terrain is selected from the group consisting of ascending ramp, descending ramp, ascending stair, descending stair, level surface.

23. The apparatus of claim 22, wherein a controller associated with the apparatus determines the property of the underlying terrain on an intra-cycle basis.

24. A lower-extremity prosthesis, comprising:

a foot member;

a lower leg member;

an ankle joint for connecting the foot member to the lower leg member;

a first actuator for applying torque to the ankle joint to rotate the foot member with respect to the lower leg member; and

a structural element coupled to the lower leg member and comprising an interface for coupling to a limb socket member of a wearer, wherein the structural element comprises a plurality of strain gages for determining the torque applied to the lower leg member by the actuator and the axial force applied to the lower leg member.

25. The prosthesis of claim 24, comprising an inertial measurement unit for determining an inertial pose of the lower leg member.

26. The prosthesis of claim 25, wherein the inertial measurement unit is coupled to the lower leg member.

27. The prosthesis of claim 25, wherein the inertial measurement unit is coupled to the foot member.

28. The prosthesis of claim 25, comprising a controller for calculating ground reaction force and zero moment pivot coordinates imparted by an underlying surface onto the foot member based on an inertial pose of the lower leg member, the torque applied to the lower leg member by the actuator, axial force applied to the lower leg member, and an angle between the foot member and lower leg member.

29. The prosthesis of claim 28, wherein the controller is coupled to the actuator and is configured to control the actuator for modulating at least one of an impedance, position or torque of the prosthesis throughout a walking cycle of the prosthesis based on the inertial pose trajectory of the lower leg member, the angle between the foot member and lower leg member, and the ground reaction force and the zero moment pivot coordinates.

30. The prosthesis of claim 28, wherein the controller is coupled to the actuator and is configured to control the actuator for modulating an impedance of the prosthesis as the wearer stands up from a seated position or sits down from a standing position based on the inertial pose of the lower leg member, the angle between the foot member and lower leg member, and the ground reaction force and the zero moment pivot coordinates.

31. A lower-extremity prosthesis, comprising:

a foot member;

a lower leg member;

an ankle joint for connecting the foot member to the lower leg member;

a first actuator for applying torque to the ankle joint to rotate the foot member with respect to the lower leg member;

a structural element coupled to the lower leg member and comprising an interface for coupling to a limb socket member of a wearer; and

a displacement sensing apparatus for measuring deflection of the structural element for determining the torque applied to the lower leg member by the actuator and the axial force applied to the lower leg member.

32. The prosthesis of claim 31, wherein the displacement sensing apparatus comprises a plurality of sensors and the displacement sensing apparatus measures the distance between each sensor and a surface of the structural element.

33. The prosthesis of claim 32, wherein the sensors are selected from the group consisting of contact displacement sensors, non-contact displacement sensors, inductive coils, optical sensors, force-sensitive resistors, piezoelectric sensors, or strain sensors.

34. The prosthesis of claim 32, wherein the plurality of sensors comprise a plurality of inductive coils on a circuit board.

35. The prosthesis of claim 34, wherein changes in inductance of the inductive coils relative to a surface of the structural element are used to determine the displacement of the structural element.

36. The prosthesis of claim 31, comprising an inertial measurement unit for determining an inertial pose of the lower leg member.

37. The prosthesis of claim 36, wherein the inertial measurement unit is coupled to the lower leg member.

38. The prosthesis of claim 36, wherein the inertial measurement unit is coupled to the foot member.

39. The prosthesis of claim 36, comprising a controller for calculating ground reaction force and zero moment pivot coordinates imparted by an underlying surface onto the foot member based on an inertial pose trajectory of the lower leg member, the torque applied to the lower leg member by the actuator, axial force applied to the lower leg member, and an angle between the foot member and lower leg member.

40. The prosthesis of claim 39, wherein the controller is coupled to the actuator and is configured to control the actuator for modulating an impedance of the prosthesis throughout a walking cycle of the prosthesis based on the inertial pose trajectory of the lower leg member, the angle between the foot member and lower leg member, and the ground reaction force and the zero moment pivot coordinates.

41. The prosthesis of claim 39, wherein the controller is coupled to the actuator and is configured to control the actuator for modulating an impedance of the prosthesis as the wearer stands up from a seated position or sits down from a standing position based on the inertial pose trajectory of the lower leg member, the angle between the foot member and lower leg member, and the ground reaction force.

42. A linear actuator comprising intrinsic safety features, the actuator comprising:

a rotary motor comprising a motor shaft output, wherein a pulley is coupled to the motor shaft output; and

a ball-screw transmission assembly comprising a threaded shaft coupled to the motor shaft output by a plurality of belts connected in parallel between the pulley and the threaded shaft of the ball-screw transmission assembly, wherein the ball-screw transmission assembly translates rotational motion of the motor shaft output to a linear motion of a portion of the ball-screw transmission assembly.

43. The linear actuator of claim 42, comprising an angular encoder for determining angular alignment between the rotary motor'"'"'s rotor and stator.

44. The linear actuator of claim 42, comprising a controller configured to short three leads of the rotary motor to ground in response to a belt breakage sensor detecting a failure of one or more of the plurality of belts.

45. The linear actuator of claim 44, wherein shorting the three leads results in the rotary motor functioning as a stiff, viscous brake.

46. The linear actuator of claim 42, wherein temperature of the motor is determined by applying a fixed current to a winding of the motor winding and measuring a corresponding voltage in the winding to determine the winding resistance.

47. The linear actuator of claim 42, wherein temperature of the motor is determined by applying a fixed voltage to a winding of the motor winding and measuring a corresponding current in the winding to determine the winding resistance.

48. The linear actuator of claim 42, comprising a motor temperature sensor for measuring the temperature of the motor.

49. The linear actuator of claim 42, comprising a controller coupled to the motor for controlling torque output by the actuator based on temperature of the motor.