Grasping Device Control Using Parallel Bi-Directional State Flow Maps
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Solution Overview
Problem
Conventional grasping mechanical devices, such as robotic prosthetic hands, lack the ability to simulate discrete movements and are limited in their functionality, requiring multiple EMG signals for control, which can be cumbersome and unreliable, especially for transhumeral amputees with limited independent EMG signals.
Innovation Solution
A control system using parallel, bi-directional state flow maps that allow continuous control of joints in grasping devices based on EMG signals and the current mechanical state, enabling direct and proportional control with a single bidirectional input, reducing the need for complex pattern recognition and minimizing cognitive effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional myoelectric devices use multiple EMG signals for control, then the ability to perform discrete movements is improved, but the device complexity and cognitive effort required increase significantly
Solution Approach 1:
A single bidirectional EMG input channel controls multiple degrees of freedom through state flow maps. The system uses one EMG signal that can activate different joint sequences depending on the current state, allowing the same input to produce multiple different movements (e.g., opening hand, closing fingers, moving thumb) based on the current mechanical configuration.
Solution Approach 2:
The control system dynamically transitions between different state flow maps based on the current mechanical state of the device. As joints move through their ranges of motion, the system automatically switches between predefined sequences of poses, allowing the control behavior to adapt dynamically without requiring multiple static control channels.
2Measurement precision
If conventional grasping devices are designed with multiple independent control channels, then the precision of control is improved, but the ease of operation deteriorates due to increased cognitive load
Solution Approach 1:
The system uses the current mechanical state of the device itself to determine the appropriate control sequence. The device's own configuration (which joints are in what positions) automatically selects the next action through the state flow map mechanism, eliminating the need for the user to cognitively manage multiple control channels while maintaining precise control.
3Ease of operation
If transhumeral amputees use standard interfaces with limited EMG signals, then the ease of attachment is improved, but the reliability of control deteriorates due to insufficient independent control channels
Solution Approach 1:
The system enables a single EMG channel to perform multiple control functions by leveraging the mechanical state information. This allows transhumeral amputees to reliably control multiple degrees of freedom with the limited number of EMG signals available from standard interfaces, maintaining control reliability without requiring additional attachment complexity.
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 intuitive and efficient control of multifunctional hand prostheses with reduced cognitive load, allowing for smooth transitions between poses and robust operation, compatible with standard transhumeral interfaces, and minimizing errors in grasping and releasing objects.
Implementation Method 1
receiving at least one electromyogram (EMG signal) and obtaining a current mechanical state of the grasping device
Data Source
AI summary
A method for operating a grasping device and grasping devices therefrom are provided. The grasping device is configured to use a plurality of parallel, bi-directional state flow maps each defining a sequence of poses for a plurality of joints in the grasping device. The method include receiving at least one control signal, determining a current pose of the grasping device within the one of the plurality of state flow maps currently selected for the grasping device, and selectively actuating the plurality of joints to traverse the sequence of poses, where a direction for traversing the sequence of poses is based on the at least one control signal.