Elastic Exoskeleton Joint With Anisotropic Damping and Variable Stiffness
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Solution Overview
Problem
Existing exoskeleton joints are typically rigid and lack the complexity and flexibility to accurately replicate human joint movements, particularly in terms of rotational and translational degrees of freedom, which can lead to restricted movement and potential joint damage.
Innovation Solution
A joint device with a damping system that allows for both rotational and translational degrees of freedom, featuring a concentric arrangement with a damping device that differentially dampens these movements, and an adjustable axle body with varying elasticity to mimic human joint characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid joints are used in exoskeletons to provide structural support, then structural strength is improved, but movement flexibility and naturalness deteriorate
Solution Approach 1:
The patent applies parameter changes by transitioning from rigid joints to elastic joints with variable stiffness characteristics. The elastic joint allows the system to change its mechanical parameters (stiffness, damping) dynamically, enabling it to adapt between providing structural support and allowing natural movement patterns.
Solution Approach 2:
The patent employs composite materials in the form of elastic elements combining different material properties. These composite structures provide both the necessary strength for structural support and the elasticity required for flexible, natural movement, resolving the contradiction between rigidity and flexibility.
2Device complexity
If simple rotational joints are used to reduce complexity, then device complexity is reduced, but ability to replicate human joint movements deteriorates
Solution Approach 1:
The elastic joint serves multiple functions simultaneously: it provides rotational movement, translational movement, damping, and stiffness control. This multi-functionality allows a single joint design to replicate the complex behavior of human joints without requiring multiple separate mechanisms.
Solution Approach 2:
The patent applies dynamics by creating joints with time-varying stiffness and damping characteristics that can adapt during movement. This dynamic behavior enables the joint to replicate the complex, non-linear characteristics of human joint movements while maintaining a relatively simple structural design.
3Reliability
If externally mounted damping devices are used to control joint movement, then damping control is improved, but joint flexibility and range of motion deteriorate
Solution Approach 1:
The patent merges the damping function with the joint structure itself by integrating elastic elements directly into the joint. This combination eliminates the need for separate external damping devices while maintaining both effective damping control and full joint flexibility, as the elastic elements provide both support and compliance.
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 more natural and complex human-like movements by providing anisotropic damping and adjustable stiffness, reducing the risk of joint damage and enhancing the usability of exoskeletons.
Implementation Method 1
the damping device is arranged between the first joint element and the second joint element in such a way that it dampens the translational degree of freedom more strongly than the rotational degree of freedom
Implementation Method 2
an elastic element that is rigidly connected to two plates
Data Source
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Figure 3
Figure 4~5
AI summary
In order to implement complex rotational movements, e.g. a rotational movement that can be characterized by a linear displacement of the current center of rotation and an angular change of the rotational axis relative to the component, the invention proposes a flexible and, under certain circumstances, adaptively controllable or programmable device. The device comprises at least two articulation elements and a connection element, but can be supplemented by further elements such as a sensor unit, an actuating unit, a conversion and transmission unit, a control unit and, with respect to rigidity and damping, specially designed cores. The control can, for example, be carried out according to predetermined characteristic curves, e.g. with respect to the axial position, or as a function of a load. The device can be integrated, for example, into exoskeletons, e.g. for lower extremities, in order to map the knee movement (bending and stretching) in the technical system.