Neuromuscular Controller for Robotic Leg Adaptation
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Solution Overview
Problem
Existing prosthetic ankles lack the ability to adapt biomimetically to changes in terrain slope and walking speed, and they do not provide sufficient stance phase power for normal gait, as they rely on fixed state relationships that do not account for environmental disturbances or rapid terrain variations.
Innovation Solution
A neuromuscular model-based controller that incorporates a muscle model, muscle geometry, and a reflex feedback loop to adjust muscle activation based on sensory data from intrinsic and extrinsic sensors, allowing for dynamic adaptation of torque and impedance commands to match the wearer's intent and environmental changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed ankle state relationships are used for control, then the controller is simple to implement, but the prosthesis cannot adapt to changes in terrain slope and walking speed
Solution Approach 1:
The patent implements dynamic adaptation by using a microprocessor to continuously adjust ankle joint parameters (position, torque, impedance) based on real-time sensing of terrain conditions and walking speed. The controller transitions from fixed relationships to dynamic, adaptive control that modifies its behavior consequent to environmental changes, resolving the contradiction between simplicity and adaptability.
Solution Approach 2:
The patent employs feedback mechanisms where sensors detect terrain slope, walking speed, and joint position, and this information is fed back to the microprocessor which adjusts control parameters accordingly. This closed-loop feedback system enables the prosthesis to adapt to changing conditions while maintaining manageable complexity through algorithmic processing.
2Adaptability or versatility
If microprocessor control is implemented, then adaptation to terrain changes is enabled, but sufficient stance phase power for normal gait is not provided
Solution Approach 1:
The patent addresses the power deficiency by dynamically changing control parameters including torque magnitude, impedance levels, and joint position targets during the stance phase. The microprocessor adjusts these parameters based on terrain slope and walking speed sensing, enabling the prosthesis to generate sufficient power for normal gait while maintaining adaptability to environmental conditions.
3Stability of the object's composition
If fixed control schemes are used, then steady-state gait is maintained, but adaptation to environmental disturbances and rapid terrain variations is prevented
Solution Approach 1:
The patent resolves this contradiction by implementing dynamic control that continuously monitors environmental disturbances and rapidly adjusts control parameters. The system maintains steady-state gait stability through baseline control while enabling rapid adaptation to disturbances through real-time parameter modification based on sensor feedback, allowing the prosthesis to respond to both steady-state and transient conditions.
Data Source
AI summary
A neuromuscular model-based controller for a robotic limb having at least one joint includes a neuromuscular model having a muscle model, muscle geometry and reflex feedback loop to determine at least one torque or impedance command to be sent to the robotic limb. One or more parameters that determine relation between feedback data and activation of the muscle model are adjusted consequent to sensory data from at least one of an intrinsic sensor and an extrinsic sensor. A controller in communication with the neuromuscular model is configured to receive the at least one torque or impedance command and controls at least one of position, torque and impedance of the robotic limb joint.