Exoskeleton Gait Control for Continuous Walking Motion
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Solution Overview
Problem
Current exoskeleton devices lack comprehensive and user-friendly control systems that enable continuous walking motion, resulting in inefficient and clunky gait due to significant dwell time in static states, which limits walking speed and user intent determination.
Innovation Solution
A control method for a powered lower extremity orthosis exoskeleton that initiates joint motion during dynamic phases of the gait cycle, minimizing or eliminating static states and allowing continuous motion by determining user intent during dynamic states, using sensors to detect angular positions and velocities to switch between advanced and standard gait controls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional gait control with static states is used, then safety and stability are improved, but walking speed and gait smoothness deteriorate due to significant dwell time in static states
Solution Approach 1:
The patent transitions the exoskeleton control system from static gait states to continuous dynamic motion. The control application executes advanced gait control that maintains at least one joint in motion throughout the gait cycle, eliminating traditional static double-support phases. This dynamic approach allows the system to determine user intent during motion rather than during stationary periods, thereby increasing walking speed while maintaining safety through continuous sensor monitoring and adaptive control adjustments.
Solution Approach 2:
The patent implements continuous useful action by ensuring that at least one joint remains in motion during the entire gait cycle. The control system transitions from discrete static-dynamic state transitions to continuous motion where joints seamlessly transition between swing and stance phases. This eliminates dwell time in static states while maintaining gait stability through continuous control adjustments based on real-time sensor feedback from multiple joints.
2Productivity
If advanced gait control with continuous motion is implemented, then walking speed and gait smoothness are improved, but control complexity increases
Solution Approach 1:
The patent segments the gait control into independent joint-level control modules, each with its own control application executing advanced gait control algorithms. Rather than managing complex whole-body dynamics, the system divides control into manageable joint-specific segments that can be independently optimized. This modular segmentation reduces overall control complexity while enabling continuous motion and higher walking speeds through coordinated joint actions.
Solution Approach 2:
The patent implements comprehensive feedback mechanisms where sensors continuously monitor joint positions, velocities, and accelerations during dynamic motion. The control application uses this real-time feedback to determine user intent and adjust control commands adaptively. This feedback loop enables the system to manage increased control complexity through data-driven decision-making, allowing advanced gait control to achieve higher walking speeds while maintaining safety and stability.
3Loss of time
If joint motion is initiated during dynamic phases rather than static states, then dwell time is reduced and walking speed increases, but difficulty in determining user intent increases
Solution Approach 1:
The patent applies preliminary action by preparing control commands in advance during the dynamic swing phase, before the foot contacts the ground. The control system uses sensor data collected during motion to predict and pre-position joints for the next phase, reducing dwell time while maintaining accurate user intent determination. This allows the system to make control decisions based on dynamic motion patterns rather than waiting for static state transitions.
Solution Approach 2:
The patent replaces mechanical static-state-based intent detection with sensor-based electronic detection during dynamic motion. Instead of relying on mechanical switches or position sensors that require static states for accurate reading, the system uses accelerometers, gyroscopes, and magnetic sensors to detect user intent during continuous motion. This substitution enables accurate intent determination while maintaining continuous joint motion and eliminating dwell time.
Data Source
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AI summary
A method of controlling an exoskeleton mobility device includes executing a control application with an electronic controller to perform: sensing at least one of an angular position or angular velocity of a stance/trailing leg during a single support dynamic state of a gait cycle; determining whether the angular position satisfies an advanced gait threshold; and when it is determined that the angular position satisfies the advanced gait threshold, the control system employs advanced gait control in which a duration of double support states between single support dynamic states is minimized. For advanced gait control the control system controls such that hip joint component velocities are non-zero during transitions from swing states to stance states, and knee joint component velocities are non-zero during transitions from stance states to swing states of the gait cycle. Each step of the gait cycle thus blends into a next step by way of hip joint component swing-to-stance extension, and/or knee joint component stance-to-swing flexion.