Powered Exoskeleton Gait Control for Continuous Step Transitions
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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 system that initiates joint motion during dynamic phases of the gait cycle, minimizing or eliminating static states by determining user intent during single support dynamic states and utilizing advanced gait joint trajectories with non-zero velocities for hip and knee joints, allowing continuous motion and faster walking speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional gait control with static states is used, then user intent can be determined during double support states, but walking speed is limited due to significant dwell time in static states
Solution Approach 1:
The control system determines user intent during dynamic single support states before transitioning to the next phase, rather than waiting for static double support states. This preliminary determination of intent during motion eliminates the need for prolonged static dwelling time, thereby increasing walking speed while maintaining safe control decisions
Solution Approach 2:
The system maintains continuous joint motion throughout the gait cycle by initiating swing phase movements during the latter portion of stance phase. This continuous action eliminates idle static periods between steps, keeping the exoskeleton in constant productive motion and significantly reducing overall dwell time while maintaining gait stability
2Productivity
If joint motion is initiated during static double support states, then gait transitions are stable, but motion is interrupted and walking efficiency decreases
Solution Approach 1:
The control system initiates swing phase joint motions during the latter portion of the stance phase while the user is still in dynamic single support. This preliminary initiation of motion during the previous dynamic state eliminates the need to start motion from a static position, maintaining continuous momentum and improving walking efficiency while preserving stability through proper timing
Solution Approach 2:
The system transitions from static gait control to dynamic gait control by initiating joint motions during dynamic states rather than from static positions. This dynamic approach maintains continuous motion flow, improves walking efficiency, and adapts the gait cycle to match natural human movement patterns where transitions occur during motion rather than from rest
Data Source
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.