Articulated Hand Prosthesis With Progressive Spring Chassis
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Solution Overview
Problem
Conventional hand prostheses lack a natural appearance and feel, leading to an artificial impression when interacting with others or objects, due to rigid components and lack of elastic features.
Innovation Solution
A hand prosthesis with a chassis kept in a neutral position by a progressive spring element, allowing for soft mobility and increased counteracting force at end positions, combined with a locking device for fine angle graduation and rotational movement, mimicking natural hand movements and appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rigid components are used in the hand prosthesis, then structural strength and stability are improved, but the natural appearance and soft feel are deteriorated
Solution Approach 1:
The patent applies parameter changes by using a progressive spring element that changes its spring constant based on the deflection angle. At small angles (neutral position), the spring constant is low providing soft mobility. At large angles (end positions), the spring constant increases providing higher counteracting force. This dynamic parameter change resolves the contradiction between needing strength for structural integrity and softness for natural appearance.
Solution Approach 2:
The patent uses a composite approach by combining rigid chassis components with a progressive spring element that provides elastic deformation. The spring element acts as a compliant component between rigid parts, creating a composite system that exhibits both strength and softness characteristics, thereby achieving natural appearance while maintaining structural integrity.
2Ease of manufacture
If a progressive spring element is used to provide soft mobility at neutral position, then natural appearance is improved, but the complexity of the spring mechanism is increased
Solution Approach 1:
The progressive spring element achieves complex behavior (variable stiffness) through geometric design rather than multiple components. The spring constant changes with deflection angle due to the progressive winding pattern, allowing a single element to replace what would otherwise require complex multi-component mechanisms for achieving soft-hard transition.
3Reliability
If the spring element provides increased counteracting force at end positions, then protection against hard impact is improved, but the mobility in neutral position is reduced
Solution Approach 1:
The progressive spring element dynamically changes its spring constant based on the deflection angle. In the neutral position (small angles), the spring constant is low, allowing easy mobility and natural movement. As the deflection angle increases toward end positions, the spring constant progressively increases, providing stronger counteracting force to prevent hard impacts. This parameter change with operating condition resolves the contradiction between mobility and protection.
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 solution enhances the natural appearance and functionality of the hand prosthesis, providing improved user acceptance by replicating natural hand movements and reducing mechanical stress, while allowing for secure object handling.
Implementation Method 1
The chassis is kept in a neutral position against a spring force provided by at least one spring element associated with the chassis, which has a progressive spring characteristic and, with increasing flexion or extension angles, offers an increasing counteracting force toward the neutral position.
Implementation Method 2
The spring element is formed such that a progressive spring characteristic is obtained for increasing flexion or extension angles, so that it is possible in the neutral position of the hand to obtain a soft characteristic and easy mobility within the neutral position and in a small angular range around it.
Implementation Method 3
The spring element may be formed as a torsion spring, which operates both in the direction of extension and in the direction of flexion.
Data Source
AI summary
The invention relates to a hand prosthesis comprising a chassis and coupling elements for fastening the hand prosthesis to the stump of an arm and comprising at least one joint for the flexion and extension of the hand prosthesis in relation to the coupling elements, the chassis being kept in a neutral position against a spring force.