Admittance shaping controller for exoskeleton assistance of the lower extremities
First Claim
1. An exoskeleton system for assisted movement of legs of a user comprising:
- a harness worn around a waist of the user;
a pair of arm members coupled to the harness and to the legs;
a pair of motor devices, wherein one of the pair of motor devices is coupled to a corresponding arm member of the pair of arm members moving the pair of arm members for assisted movement of the legs;
a controller coupled to the motor controlling movement of the assisted legs, the controller shaping an admittance of the system facilitating movement of the assisted legs by generating a target DC gain, a target natural frequency and a target resonant peak; and
wherein the dynamics of the leg are modeled as a transfer function of a linear time-invariant (LTI) system, the controller replacing the natural admittance of the leg by the equivalent admittance of the coupled system formed by the leg and the exoskeleton.
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Accused Products
Abstract
The control method for lower-limb assistive exoskeletons assists human movement by producing a desired dynamic response on the human leg. Wearing the exoskeleton replaces the leg'"'"'s natural admittance with the equivalent admittance of the coupled system formed by the leg and the exoskeleton. The control goal is to make the leg obey an admittance model defined by target values of natural frequency, resonant peak magnitude and zero-frequency response. The control achieves these objectives objective via positive feedback of the leg'"'"'s angular position and angular acceleration. The method achieves simultaneous performance and robust stability through a constrained optimization that maximizes the system'"'"'s gain margins while ensuring the desired location of its dominant poles.
32 Citations
10 Claims
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1. An exoskeleton system for assisted movement of legs of a user comprising:
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a harness worn around a waist of the user; a pair of arm members coupled to the harness and to the legs; a pair of motor devices, wherein one of the pair of motor devices is coupled to a corresponding arm member of the pair of arm members moving the pair of arm members for assisted movement of the legs; a controller coupled to the motor controlling movement of the assisted legs, the controller shaping an admittance of the system facilitating movement of the assisted legs by generating a target DC gain, a target natural frequency and a target resonant peak; and wherein the dynamics of the leg are modeled as a transfer function of a linear time-invariant (LTI) system, the controller replacing the natural admittance of the leg by the equivalent admittance of the coupled system formed by the leg and the exoskeleton. - View Dependent Claims (2)
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3. A computer-readable medium having instructions stored therein that, when executed by one or more processors of an exoskeleton system coupled to a user, cause the one or more processors to:
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calculate ratios between unassisted leg movement and a desired value through natural frequencies, resonant peaks, and DC gains of an exoskeleton; calculate angular position feedback gain kDC of the exoskeleton system; calculate target admittance parameters ω
dnh and ζ
dh;obtain a dominant pole of a target admittance as - View Dependent Claims (4, 5, 6, 7, 8, 9, 10)
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Specification