Prosthetic Hand Grasping Stability via Elastic Secondary Force
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Solution Overview
Problem
Current myoelectric prosthetic hands face issues with stability in grasping due to 'ejection' phenomena, where the fingers tend to move away from objects, limiting their functionality and ease of use in daily tasks, especially since they often allow only a limited number of grasp patterns and are prone to losing stability.
Innovation Solution
A device comprising an actuator, proximal, and tip elements connected by a pivot point and a cable, with an elastic mechanism providing a secondary force to counteract the primary force from the actuator, minimizing 'ejection' by using springs to reinforce the grasp, and a method involving sensors and image capturing to select appropriate grasp patterns based on object shape and distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If an underactuated mechanism is used to reduce the weight of the prosthetic hand, then the weight is reduced and fatigue is decreased, but the stability in grasping is lost due to ejection
Solution Approach 1:
The patent changes the force parameters by introducing an elastic mechanism that provides a secondary force in the opposite direction to the actuator's primary force. This counteracting force prevents the ejection effect while maintaining the underactuated lightweight structure, thereby resolving the contradiction between weight reduction and grasping stability.
2Device complexity
If the number of actuators is reduced to decrease device complexity and weight, then the prosthetic hand becomes lighter and simpler, but the number of grasp patterns is limited
Solution Approach 1:
The elastic mechanism serves multiple functions: it counteracts the ejection effect to improve grasping stability, enables a greater number of grasp patterns by providing additional force control, and maintains the lightweight underactuated structure. This multi-functionality resolves the contradiction between device simplicity and grasp pattern versatility.
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 stability and functionality of prosthetic hands by preventing 'ejection' and allowing for a wider range of grasp patterns, improving the user's ability to interact with various objects effectively.
Implementation Method 1
an elastic mechanism acts on the cable to provide a secondary force which displaces the proximal and tip elements towards the object
Data Source
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AI summary
The present invention relates to a device for grasping an object, the device comprises an actuator providing a primary force; a proximal element proximal to the actuator; and a tip element distal to the actuator, wherein the actuator provides a primary force on the proximal and tip elements; the proximal and tip elements are coupled by a pivot point connected by a cable to the actuator, and an elastic mechanism acts on the cable to provide a secondary force which displaces the proximal and tip elements towards the object. The present invention also relates to a method of of controlling a device for grasping an object and myoelectric prosthetic hand.