Robot Hand Planetary Gear Segmentation for Grasping
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Solution Overview
Problem
Existing robot hands face challenges in securely grasping variously shaped objects and efficiently performing grasping motions due to limitations in motor control, resistance distribution, and uniform force application, particularly when dealing with randomly stacked or compartmentalized items.
Innovation Solution
The robot hand employs a planetary gear unit with distinct power output paths and a resistance generating unit to allow independent movement of finger joints, enabling bending from the finger root to the fingertip without complex controls, and utilizes multiple planetary gear units to distribute power and resistances for efficient grasping and motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a serial-type robot hand with a single motor driving multiple joints is used to change finger shapes to follow work shape, then adaptability to variously shaped objects is improved, but device complexity increases due to mechanical coordination requirements
Solution Approach 1:
The power transmission system is segmented into multiple independent planetary gear units, each driving a separate finger joint. This allows each joint to be controlled independently while maintaining the ability to grasp variously shaped objects, reducing mechanical coordination complexity.
Solution Approach 2:
The robot hand employs dynamic power distribution where the planetary gear units can operate independently or in coordination based on the grasping requirements. This dynamic control enables adaptability to various shapes without requiring complex pre-programmed mechanical coordination.
2Productivity
If the reduction ratio of power transmission is decreased to increase finger moving speed, then productivity is improved, but grasping force (torque) decreases
Solution Approach 1:
The system dynamically adjusts the reduction ratio of planetary gear units based on operational requirements. During insertion phases, a lower reduction ratio provides higher speed, while during grasping phases, a higher reduction ratio provides greater torque, resolving the speed-force tradeoff.
Solution Approach 2:
The reduction ratio parameter of the planetary gear units is made variable rather than fixed. This allows the system to optimize the balance between moving speed and grasping force depending on the specific task phase, whether insertion or grasping.
3Adaptability or versatility
If fingers are inserted into narrow gaps with fingertips bent to reach works, then adaptability to stacked or compartmentalized objects is improved, but ease of operation deteriorates due to difficult operations
Solution Approach 1:
Each finger joint is independently controllable through separate planetary gear units, allowing the finger to be extended straight rather than bent. This segmentation of control enables insertion into narrow gaps without the operational difficulty of bent fingertips.
Solution Approach 2:
Instead of bending the fingertip to reach into gaps, the system inverts the approach by extending the entire finger straight and using independent joint control to navigate the gap, making insertion easier and more intuitive.
4Adaptability or versatility
If external force is applied to adjust work position during operator-robot cooperative operation, then adaptability to manual adjustment is improved, but uniformity of grasping forces deteriorates
Solution Approach 1:
The system incorporates feedback mechanisms that detect changes in grasping forces caused by external manual adjustments. This feedback enables real-time compensation to maintain uniform grasping forces across all fingers during operator-robot cooperative operations.
Solution Approach 2:
The power transmission system dynamically responds to external forces applied during cooperative operations. When manual adjustment is detected, the planetary gear units adjust power distribution to maintain uniform grasping forces, preserving both adaptability and force uniformity.
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 configuration allows for secure grasping of variously shaped objects, reduces operational time, and maintains uniform grasping forces without decreasing torque, facilitating flexible and efficient grasping motions.
Implementation Method 1
a planetary gear unit to which a rotational power from a power source is input; first and second drive shafts to which a rotational power output from the planetary gear unit is transmitted
Implementation Method 2
a resistance generating unit configured to make a motion resistance of the second power output part larger than a motion resistance of the first power output part
Data Source
Figure 1
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AI summary
The robot hand includes a planetary gear unit into which a rotational power is input from a motor, first and second drive shafts to which a rotational power output from the planetary gear unit is transmitted, a finger having first and second joints respectively driven by the first and second drive shafts. The planetary gear unit includes a sun gear, a planetary gear meshing with external teeth of the sun gear, a planetary arm connected to the planetary gear to coordinately move with a rotation of the planetary gear on its own axis. The sun gear is connected to the motor. The planetary arm is connected to the first drive shaft. An internal gear is connected to the second drive shaft. A resistance generating unit is disposed for making the motion resistance of the internal gear lager than the motion resistance of the planetary arm.