Prosthesis Sequential Digit Engagement for Variable Grip Control
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Solution Overview
Problem
Existing prosthetic hands with motor-driven digits lack the ability to control grip force and flexibility, as all digits typically engage an object simultaneously, limiting user control over the grip level.
Innovation Solution
A prosthesis with movable components, each driven by a motor, features a control device that determines when movement is arrested against a surface, allowing sequential engagement of further components, and provides driving electrical pulses to increase gripping force, enabling variable grip control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If all digits engage the object simultaneously, then the gripping action is simple and fast, but the user cannot control the level of grip force
Solution Approach 1:
The patent segments the digit engagement process into sequential stages, where digits engage the object one after another rather than simultaneously. The control device activates digits in a predetermined sequence (e.g., thumb first, then index finger, then middle finger), allowing the user to control grip force by determining when to stop the sequential engagement process.
Solution Approach 2:
The patent implements dynamic control of the gripping process by allowing the user to interrupt the sequential digit engagement at any stage. The system transitions from a static all-or-nothing grip to a dynamic process where the user can modulate grip force by controlling which digits are currently engaged, enabling variable grip levels.
2Adaptability or versatility
If sequential movement of components is implemented, then grip force control is improved, but the control system becomes more complex
Solution Approach 1:
The patent employs preliminary action by pre-programming the sequential engagement sequence of digits. The control device is configured with a predetermined sequence (thumb, index finger, middle finger, etc.) that automatically executes, reducing the complexity of real-time control decisions while maintaining adaptability through the ability to interrupt at any stage.
3Volume of moving object
If motors are made smaller to accommodate hand prosthesis, then the prosthesis fits better, but the gripping force is reduced
Solution Approach 1:
The patent merges the gripping force contribution from multiple digits working in sequence. While each individual motor remains small, the cumulative effect of multiple digits engaging the object sequentially produces sufficient total gripping force. The force is distributed across multiple actuators rather than requiring one large motor.
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
This solution allows for precise control over grip force and flexibility by sequentially engaging digits and applying electrical pulses, enhancing the quality of grip and accommodating constrained motor sizes.
Implementation Method 1
the control circuitry is configured to detect when movement of the component is arrested by monitoring current drawn through the motor
Implementation Method 2
moving at least a first component by means of a motor
Data Source
AI summary
A prosthesis or an orthosis and a method of controlling movable components of the same. The prosthesis or orthosis comprises a plurality of movable components, each component being movable by a respective motor and a control device operative to determine when movement of at least a first component is arrested when the at least first component bears against a surface, and to move one or more further components with respective one or more further motors so that each subsequent component is moved upon determination that the movement of the preceding component is arrested when the preceding component bears against a surface.