Underactuated Robotic Hand With Motorized Shaft Actuation
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Solution Overview
Problem
Existing robotic hands face challenges in independently controlling the movements of multiple phalanges with a limited number of actuators, leading to a high degree of underactivation, which restricts their ability to grasp various objects and communicate effectively.
Innovation Solution
A robotic hand design featuring a motorized shaft with radial profiles that allows two distinct finger movements from a rest position to a compressed position using a single actuator, enabling the hand to transition between open, closed, and extended index configurations while maintaining a high degree of underactivation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single actuator is used to control multiple fingers, then the number of actuators is reduced, but the control precision and independent movement capability of each finger deteriorates
Solution Approach 1:
The single actuator is segmented into multiple independent actuation systems through the shaft, with each finger having its own cable and crimping mechanism. This allows the single actuator to independently control multiple fingers while maintaining control precision for each finger's movement.
Solution Approach 2:
The shaft serves multiple functions: it acts as the actuator support, cable guide, and movement transmission mechanism for all fingers. This multi-functional design reduces the overall number of components while maintaining the ability to control each finger independently.
2Device complexity
If the hand is highly underactuated with fewer actuators, then the device complexity is reduced, but the ability to grasp objects of various shapes and communicate effectively deteriorates
Solution Approach 1:
The hand design allows dynamic adaptation of finger positions through the shaft's ability to control fingers in different directions (first direction for closing, second direction for opening/extending). This dynamic control enables the hand to adapt to various object shapes and communication gestures despite having fewer actuators.
Solution Approach 2:
The system changes the control parameters by using bidirectional shaft rotation to control finger movement in opposite directions. By rotating the shaft in the first direction, fingers move toward the palm; by rotating in the second direction, fingers extend away from the palm, enabling versatile grasping and communication capabilities.
3Adaptability or versatility
If a lifting beam is used to distribute gripping force, then the hand can grasp objects of various shapes, but the control is limited to only open and closed positions
Solution Approach 1:
Instead of using a single lifting beam that controls all fingers simultaneously, the invention segments the control by providing individual cables and crimpings for each finger connected to the shaft. This segmentation allows independent control of each finger's position while maintaining the ability to grasp various object shapes.
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
Enhances the humanoid character and interactive capabilities of robots by allowing more complex hand movements with fewer actuators, improving object grasping and visual communication without increasing the number of actuators required.
Implementation Method 1
each of the fingers being able to be moved relative to the palm between a rest position maintained by a spring effect and a compressed position obtained by driving a connecting piece between said finger and the palm, by countering the spring effect
Data Source
Figure 1a~1b
Figure 2a~2c
Figure 3a~3b
AI summary
The invention relates to a hand to be provided on a humanoid robot. The hand includes a palm and a plurality of fingers (12, 13, 14). Each finger (12, 13, 14) is movable, relative to the palm, between a rest position, maintained by means of a spring effect, and a compressed position, obtained by driving a connecting part (22, 23, 24) using the palm countering the spring effect. Said hand is characterized in that it includes a motor-driven shaft (20), connected to the connecting part (22, 23, 24) of each finger (12, 13, 14), and configured such as to move at least one first finger (12) and at least one second finger (13), respectively, from the rest position to the compressed position, by rotating the motor-driven shaft (20), in a first rotational direction and in an opposite direction, respectively.