Knee Orthosis Actuator Triangle Geometry for Biomechanical Support
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Solution Overview
Problem
Existing knee orthoses are bulky and complex, compromising both functionality and cosmetic quality, particularly in the mediolateral orientation, and do not provide optimal biomechanical support and resistance moments.
Innovation Solution
A knee orthosis design featuring a thigh structure with a joint mechanism coupled to a lower leg structure, where the actuator unit's fastening points and joint center form a triangle, allowing for non-linear resistance moments and progressive damping, achieved through a hydraulic damper with strategically arranged valves and sensors, enabling maximum leg support and comfort without complex control mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing knee orthoses use complex control mechanisms and sensor technology to achieve progressive damping, then biomechanical support is improved, but device complexity and space requirements increase
Solution Approach 1:
The orthosis uses the patient's own body weight and the geometric arrangement of the actuator to automatically generate the resistance moment. The system is self-regulating through the triangle geometry formed by the actuator fastening points and joint center, eliminating the need for external control mechanisms or sensors.
Solution Approach 2:
The patent replaces complex electronic control systems with a purely mechanical solution. The resistance moment is generated through the geometric configuration of the actuator unit relative to the joint center, using mechanical lever arms and force transmission rather than electronic sensors and actuators.
2Reliability
If existing knee orthoses use bulky components to provide sufficient functionality, then biomechanical support is improved, but cosmetic quality and mediolateral profile worsen
Solution Approach 1:
The actuator unit is designed to be dynamically adjustable through its geometric relationship with the joint center. The resistance moment varies automatically with the knee angle through the triangle geometry, allowing the same compact structure to provide appropriate support across different phases of movement without requiring bulky components.
Solution Approach 2:
The patent changes the parameters of the actuator unit's position and orientation relative to the joint center to optimize the mediolateral profile. By carefully selecting the fastening points that form a triangle with the joint center, the design achieves compactness while maintaining full functionality.
3Ease of manufacture
If existing knee orthoses use constant damping in the actuator unit, then manufacturing is simplified, but biomechanical support varies suboptimally across different knee angles
Solution Approach 1:
The actuator unit is designed to dynamically adjust its effective lever length through the geometric relationship between the fastening points and joint center. As the knee angle changes, the projection of the actuator force changes, automatically providing optimal biomechanical support for each phase of movement while using a simple constant-damping actuator.
Solution Approach 2:
The patent changes the effective lever arm parameter of the actuator through geometric configuration. The triangle formed by the fastening points and joint center creates a variable lever arm that automatically adapts to different knee angles, transforming a constant-damping actuator into an effectively angle-dependent support system.
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
The design provides enhanced biomechanical support and comfort by adjusting resistance moments based on knee angle, allowing for efficient stance and swing phases in patients with paralysis, while maintaining a compact and inconspicuous profile.
Implementation Method 1
hydraulic damper with strategically arranged valves and sensors, enabling maximum leg support and comfort
Data Source
AI summary
A knee orthosis and a method for controlling a knee orthosis including a thigh structure having a fastening structure to be fixed to a thigh, a lower leg structure which is pivotally coupled to the thigh rail using a joint mechanism and has a fastening structure to be fixed to a lower leg as well as a foot piece for supporting a foot, and an actuator device between the thigh structure and the lower leg structure. The fastening points of the actuator on the thigh structure and lower leg structure and the center of rotation of the joint mechanism form a triangle. The fastening points are arranged on the structures such that the connecting line between a fastening point and the center of rotation in an angular position of the knee in which the lower leg is bent at an angle ranging from 0° to 90° relative to the thigh.