Two-Legged Exoskeleton Movement With Spring-Damper Guidance
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Solution Overview
Problem
Existing exoskeletons lack a flexible and mathematically robust method for providing a variable level of assistance that allows reliable and ergonomic movement in unstructured environments, particularly for rehabilitation and mobility assistance.
Innovation Solution
A method involving a spring-damper connection simulation between the exoskeleton and a virtual guide, using a single parameter to define a theoretical trajectory, with controllers adjusting forces based on position and derivative deviations to maintain a real trajectory close to the theoretical one, allowing for a variable assistance level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a variable level of assistance is implemented using multiple controllers or complex force calculations, then the exoskeleton can provide different assistance levels, but the device complexity and mathematical complexity increase significantly
Solution Approach 1:
The patent applies parameter changes by modifying the spring-damper connection parameters (stiffness and damping coefficients) to achieve variable assistance levels. Instead of using multiple complex controllers, the system varies the physical parameters of the virtual spring-damper connection to adjust assistance, thereby reducing controller complexity while maintaining adaptability.
Solution Approach 2:
The patent introduces a virtual spring-damper connection as an intermediary between the exoskeleton actuators and the user's movements. This virtual connection simplifies the control architecture by mediating the force transmission, allowing variable assistance through parameter adjustment rather than complex multi-controller coordination.
2Ease of operation
If the exoskeleton provides high assistance force to support user movements, then the user can move more easily, but the user's own movement capability and rehabilitation progress may be reduced
Solution Approach 1:
The patent applies dynamics by making the spring-damper connection parameters variable rather than fixed. The stiffness and damping coefficients can be dynamically adjusted based on the user's rehabilitation progress and movement capabilities, allowing the system to adapt between providing high assistance when needed and reducing assistance to encourage active movement and progress.
Solution Approach 2:
The system changes the physical parameters of the virtual spring-damper connection (stiffness and damping) to balance between support and user effort. By varying these parameters, the exoskeleton can provide sufficient support for ease of movement while preventing over-assistance that would hinder rehabilitation progress.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the exoskeleton to adapt to user movements, providing stable and ergonomic support in various environments while accommodating user progress, overcoming limitations of previous methods.
Implementation Method 1
execution of a controller defining the evolution of a real position of the exoskeleton as a function of said single parameter by simulating a spring-damper connection between the exoskeleton and said virtual guide
Implementation Method 2
said controller defines forces applied to said exoskeleton, in particular an elastic restoring force and an impedance force
Implementation Method 3
said impedance force is a function of a deviation between a derivative of the actual position of the exoskeleton and a derivative of the theoretical position of the exoskeleton along the virtual guide
Implementation Method 4
Actuators allow these joints to move, which in turn move the operator
Implementation Method 5
The exoskeleton is then used to guide the patients' limbs along a predetermined path... This force applied in favor of appropriate movements and against inappropriate movements is called 'assistance'
Data Source
Figure 1
Figure 2
Figure 3(a)~3(c)
AI summary
The present invention relates to a method for moving a two-legged exoskeleton (1) receiving a human operator, the method comprising the implementation, by data processing means (11c) of the exoskeleton (1), of steps of: (a) obtaining a theoretical basic trajectory of the exoskeleton (1) corresponding to one step; (b) setting the parameters of the theoretical basic trajectory based on a single parameter so as to define the theoretical basic trajectory of the exoskeleton (1) as a virtual guide with a single degree of freedom; (c) in response to forced movements of the exoskeleton (1) made by the human operator, operating a controller defining the progression from an actual position of the exoskeleton (1) based on said single parameter by stimulating a spring-damper link between the exoskeleton (1) and the virtual guide so as to implement an actual basic trajectory close to the theoretical basic trajectory.