Parallel-Link Robot Joint for Backlash-Free Wrist Motion
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Solution Overview
Problem
Existing robot joint devices face challenges in precision control and durability due to gear tolerances, backlash, and restricted motion ranges, particularly when implementing pitching and yawing motions, limiting their ability to achieve various joint angles.
Innovation Solution
A robot joint device with a parallel link structure and rotation axes at its center, featuring adjustable links, a gear reduction unit, and a pulley system with universal joints and a rotation restricting mechanism, allowing for three degrees of freedom and improved durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a robot joint device uses multiple engaged gears to manipulate the joint, then various combinations of motions can be implemented, but precision control becomes difficult and durability deteriorates due to tolerances between gears, backlash and friction occurring in gear teeth
Solution Approach 1:
The patent extracts and removes the gear train from the robot joint device, replacing it with a direct-drive mechanism where the motor rotates the output body directly. This eliminates gear teeth, tolerances, backlash, and friction, thereby solving the precision control problem while maintaining motion versatility through the parallel link structure
Solution Approach 2:
The patent replaces the mechanical gear transmission system with a direct motor-to-output-body connection. The motor's rotational force is transmitted directly to the output body without intermediate gear components, substituting a complex mechanical transmission system with a simpler direct-drive mechanism that improves precision and durability
2Adaptability or versatility
If the robot joint device uses engaged gears to implement pitching and yawing motions, then motion combinations are achieved, but the range of pitching motion is restricted to 0 degree to about 150 degrees due to contact between the output body and input bodies
Solution Approach 1:
The patent removes the gear train that caused the motion range restriction. Without the gear teeth and engaged components, the output body can rotate freely through a much wider angle range (oretically -180 to +180 degrees) without contacting other components, thereby expanding the ease of operation while maintaining motion versatility
Solution Approach 2:
Instead of using gears to transmit and combine motions, the patent inverts the approach by using a parallel link structure where multiple links connect the input and output bodies directly. This inverted mechanism allows the output body to achieve various motion combinations through the geometric constraints of the parallel links rather than through gear engagement, enabling a wider range of motion
3Adaptability or versatility
If the robot joint device uses multiple engaged gears, then various joint angles can be manipulated, but durability deteriorates due to tolerances between gears and friction in gear teeth
Solution Approach 1:
The patent extracts and eliminates the gear train from the system, removing the source of durability problems. The direct-drive mechanism has no gear teeth to wear, no tolerances to accumulate, and no friction between meshing components, thereby significantly improving durability and reliability while maintaining the ability to manipulate various joint angles
Solution Approach 2:
The patent replaces the mechanical gear transmission system with a direct motor-to-output-body connection. This substitution eliminates the harmful friction and wear associated with gear teeth engagement, replacing a durability-prone mechanical transmission system with a simpler, more reliable direct-drive mechanism
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 precise control and enhances durability by allowing a wider range of motion, including pitching and yawing, while reducing interference and friction, thus mimicking human wrist movements effectively.
Implementation Method 1
a pulley connected to the second end of the rotary shaft and configured to transmit driving power to the rotary shaft
Implementation Method 2
allowing for three degrees of freedom and improved durability
Data Source
AI summary
A robot joint device including first and second plates positioned in parallel, links each having a first end connected to the first plate and a second end connected to the second plate, connecting members configured to connect the two first and second ends of each of the links and the first and second plates, respectively, so that angles and rotations of the links are adjustable relative to the first and second plates, a rotary shaft having two ends penetrating the first and second plates and rotatably installed, a gear reduction unit installed in the first plate and connected to the first end of the rotary shaft, and a pulley connected to the second end of the rotary shaft and configured to transmit driving power to the rotary shaft may be provided.