Bipedal Exoskeleton Walking Control for Uneven Terrain Stability
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Solution Overview
Problem
Existing exoskeletons struggle to maintain balance and stability on uneven terrain, leading to potential falls and injuries, as current control methods are not robust enough to handle strong disturbances or non-flat surfaces.
Innovation Solution
A method for setting in motion a biped exoskeleton that involves data processing to obtain a theoretical elementary trajectory and execute a control loop to adjust the exoskeleton's position, using an admittance controller and a flexibility model to compensate for deviations, ensuring stable walking by estimating the current state and applying a wrench to maintain balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional control methods are used for exoskeleton walking, then the exoskeleton can walk on flat ground, but it cannot withstand strong disturbances or walk on uneven terrain
Solution Approach 1:
The control method transitions from static trajectory execution to dynamic adaptive control. The system continuously estimates the exoskeleton's state and computes wrench commands in real-time to compensate for deviations caused by uneven terrain and disturbances, enabling the exoskeleton to adapt its walking behavior dynamically to maintain stability on various terrains
Solution Approach 2:
The invention implements a feedback control loop that continuously monitors the exoskeleton's actual position and state, compares it with the theoretical trajectory, and generates corrective wrench commands. This closed-loop feedback mechanism enables the system to react to disturbances and terrain variations, resolving the contradiction between terrain adaptability and walking stability
2Device complexity
If a rigid robot model is used for control, then the control implementation is simpler, but it does not accurately represent the exoskeleton's flexible behavior
Solution Approach 1:
The invention changes the control approach from rigid body dynamics to flexible structure dynamics. By incorporating flexibility parameters and models into the control formulation, the system accurately represents the exoskeleton's compliant behavior while maintaining tractable control implementation through appropriate modeling assumptions
3Reliability
If active control methods are implemented to react to disturbances, then balance can be maintained, but a gantry is still required for safety
Solution Approach 1:
The control method implements beforehand cushioning by continuously computing corrective wrench commands that anticipate and compensate for potential deviations from the desired trajectory. This proactive control approach builds safety margins into the walking control, reducing the need for external safety structures like gantries while maintaining balance
Data Source
AI summary
The present invention relates to a method for moving a bipedal exoskeleton (1) accommodating a human operator, the method comprising the implementation, by data processing means (11c) of the exoskeleton (1), of steps of: (a) obtaining a theoretical elementary trajectory of the exoskeleton (1); (b) executing a control loop defining the change in an actual position of the exoskeleton (1) so as to implement an actual elementary trajectory close to said theoretical elementary trajectory, comprising, in each iteration of the loop: —estimating a current state of the exoskeleton (1) as a function of said actual position; —determining a force torsor to be applied to the exoskeleton (1) in the next iteration of the loop to compensate for a deviation between said estimated current state of the exoskeleton (1) and an expected state of the exoskeleton (1) according to said theoretical elementary trajectory; the determination of the force torsor and/or the application thereof to the exoskeleton (1) taking into account a model of the flexibility of the exoskeleton (1) with respect to a rigid robot.