Movement assistance device

Patent metadata

Field	Value
Publication number	US-9566705-B2
Application number	US-201314408094-A
Country	US
Kind code	B2
Filing date	Jun 17, 2013
Priority date	Jun 15, 2012
Publication date	Feb 14, 2017
Grant date	Feb 14, 2017

Abstract

An exoskeleton for applying force to at least one lower limb of a user includes a control system with a sensor interface for sensor signals; a power interface for transmitting control signals to the powered joint; a processor coupled to the sensor and the power interfaces; and a computer-readable medium storing a computer program executable on the processor with code sections for: estimating a configuration of a body of the user with respect to a gravity vector based on the sensor signals; computing a control torque for the powered joint that compensates gravitational dynamics of the user based on the configuration; calculating a gravitational energy gradient for the powered joint; attenuating the control torque based on the gravitational energy gradient; computing a final control torque based on the attenuated control torque, and configuring the control signals based on the attenuated control torque.

First claim

What is claimed is:

1. A method for the control of an exoskeleton comprising a plurality of segments and one or more powered joints associated with lower limbs of a user, the method comprising:
obtaining a configuration of a body of the user associated with the exoskeleton with respect to an inertia reference frame and an angular velocity of each of the powered joints;
estimating an effect of gravity on the lower limbs of the user based on the configuration;
computing a first control torque for each of the powered joints that at least partially reduces the effect of gravity on an associated one of the lower limbs of the user based on the configuration;
calculating a gravitational energy gradient for each of the powered joints based on a product of the respective angular velocity and the respective first control torque;
attenuating the first control torque for each of the powered joints by an attenuation amount selected according to a sign of the respective gravitational energy gradient to yield a second control torque for each of the powered joints; and
applying a final control torque via each of the powered joints, the final control torque based, at least in part, on the respective second control torque,
wherein the attenuation amount is zero when the sign is positive, and wherein the attenuation amount is equal to the respective first control torque when the sign is negative.

2. The method of claim 1 , further comprising:
computing a third control torque for each of the powered joints that substantially compensates an effect of gravity on the exoskeleton, and
wherein the final control torque for each of the powered joints is further based on a sum of the respective second control torque and the respective third control torque.

3. The method of claim 1 , wherein the estimating of the configuration comprises utilizing at least one of a gyroscope or an accelerometer to determine an orientation of the plurality of segments relative to the inertia reference frame.

4. The method of claim 3 , wherein the estimating of the configuration further comprises sensing joint angles between the segments of the exoskeleton.

5. The method of claim 3 or 4 , wherein the estimating of the configuration further comprises:
determining whether each one of the powered joints is associated with a portion of the exoskeleton corresponding to swing leg or a support leg of the lower limbs of the user,
in response to determining that the one of the powered joints is associated with the swing leg, computing the first control torque for the one of the powered joints to at least partially compensate for the weight of the swing leg relative to a hip of the user, and
in response to ascertaining that the one of the powered joints is associated with the support leg, computing the first control torque for the one of the powered joints to at least partially compensate for the weight of the body.

6. The method of claim 5 , wherein the powered joints are associated with each of the lower limbs of the user, and wherein the computing further comprises calculating the first control torque for each of the powered joints to provide different amounts of partial gravity compensation for each of the lower limbs.

7. The method of claim 5 , wherein the computing further comprises selecting the first control torque for one of the lower limbs to provide zero gravity compensation.

8. The method of claim 5 , further comprising determining whether the lower limbs are in a single-support phase or a double-support phase based on the configuration, and adjusting an amount of compensation provided by the first control torque for the one of the powered joints differently for each of the single-support phase and the double-support phase.

9. The method of claim 8 , further comprising detecting a transition of the lower limbs between the single-support phase and the double-support phase based on measurements from at least one of a load sensor, a gyroscope, or an accelerometer associated with the exoskeleton.

10. The method of claim 9 , wherein the transition from the single-support phase and the double-support phase is detected when the measurements indicate a substantial acceleration in the swing leg along a direction of ground impact.

11. The method of claim 9 , wherein the transition from the single-support phase and the double-support phase is detected when the measurements indicate a change in a direction of an angular velocity of a shank segment of the swing leg.

12. The method of claim 8 , further comprising detecting a transition of the lower limbs between the single-support phase and the double-support phase based on a change in at least one of a direction or a magnitude of an angular velocity of at least one segment of the exoskeleton associated with the swing leg.

13. The method of claim 8 , where an amount of compensation during the single-support phase is determined based on a measured movement of the lower limbs.

14. The method of claim 13 , where the amount of compensation for a first leg of the lower limbs is based, at least in part, on the measured movement of a second leg of the lower limbs.

15. The method of claim 13 , where the amount of compensation is based on the difference between the measured movement of a first leg of the lower limbs and the measurement movement of a second leg of the lower limbs.

16. The method of claim 1 , further comprising adjusting an amount of damping for at least one of powered joints.

17. A non-transitory computer-readable medium having stored thereon a computer program executable on a computing device, the computer program comprising a plurality of code sections for performing the method of claim 1 .

18. A control system for controlling an exoskeleton comprising one or more powered joints associated with lower limbs of a user and a plurality of sensors associated with the lower limbs, the control system comprising:
a sensor interface for receiving sensor signals from the plurality of sensors;
a power interface for transmitting control signals to the at least one powered joint;
a processor communicatively coupled to the sensor interface and the power interface; and
a computer-readable medium having stored thereon a computer program executable on the processor, the computer program comprising a plurality of code sections for:
obtaining a configuration of a body of the user associated with the exoskeleton with respect to an inertia reference frame and an angular velocity of each of the powered joints based on the sensor signals at the sensor interface,
estimating an effect of gravity on the lower limbs of the user based on the configuration,
computing a first control torque for each of the powered joints that at least partially reduces an effect of gravity on an associated one of the lower limbs of the user based on the configuration;
calculating a gravitational energy gradient for each of the powered joints based on a product of the respective angular velocity and the respective first control torque,
attenuating the first control torque for each of the powered joints by an attenuation amount selected according to a sign of the respective gravitational energy gradient to yield a second control torque for each of the powered joints,
computing a final control torque for each of the powered joints, the final control torque based, at least in part, on the respective second control torque, and
configuring the control signals at the power interface to cause the final control torque to be applied at the at least one powered joint,
wherein the attenuation a

Assignees

• Univ Vanderbilt

Inventors

• Goldfarb Michael
• Murray Spencer

Classifications

• A61F2/72

  Bioelectric control, e.g. myoelectric · CPC title

• A61H2201/5007

  computer controlled · CPC title

• A61H2201/5061

  Force sensors · CPC title

• A61H2201/1642

  Holding means therefor · CPC title

• Y10S901/28

  Joint · CPC title