Magnetic Gear Actuator Unit for Low-Backlash Robot Hand Control
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Solution Overview
Problem
High-speed robot hands face challenges in achieving low backlash and low friction due to bevel gears, leading to difficulties in force and position control, especially in modes like plastically deforming, elastically deforming, and series elastic actuator modes.
Innovation Solution
An actuator unit comprising a motor, a first magnetic gear connected to the motor's rotating shaft, a second magnetic gear magnetically engaged with the first, and a planetary reducer connected to the second magnetic gear, which reduces friction and backlash, enabling effective force and position control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If bevel gears are used in the joint mechanism, then high-speed operation is achieved, but backlash and friction increase
Solution Approach 1:
The patent replaces the traditional mechanical bevel gear transmission system with a magnetic gear system. The magnetic gears use magnetic fields to transmit torque between the motor shaft and the joint mechanism, eliminating physical gear tooth contact. This substitution maintains high-speed operation capability while significantly reducing backlash and friction, thereby improving reliability for force and position control operations.
Solution Approach 2:
The patent introduces magnetic fields as an intermediary between the motor and the joint mechanism. Instead of direct mechanical contact through bevel gears, the magnetic field serves as the medium to transmit rotational motion and torque. This intermediary approach allows for smooth, contactless power transmission that maintains speed while minimizing mechanical wear and backlash.
2Force
If bevel gears are used in the joint mechanism, then torque transmission is achieved, but mechanical wear causes variation in backlash
Solution Approach 1:
The patent replaces the mechanical bevel gear system with a magnetic gear system that uses magnetic field interaction for torque transmission. This eliminates the mechanical wear that occurs in traditional gear systems, thereby preventing variation in backlash over time. The magnetic gears maintain consistent performance characteristics throughout the operational life of the mechanism.
Solution Approach 2:
The magnetic gear system is self-lubricating and wear-free by design. The magnetic field interaction requires no physical contact between moving parts, eliminating the need for lubrication and preventing wear-related degradation. This self-service characteristic ensures consistent torque transmission and stable backlash characteristics without maintenance.
3Reliability
If magnetic gears are used instead of bevel gears, then backlash and friction are reduced, but device complexity increases
Solution Approach 1:
The patent merges the motor function and gear transmission function into a single integrated magnetic gear system. The motor shaft directly generates the magnetic field that drives the magnetic gears, eliminating the need for separate mechanical gearboxes and reduction mechanisms. This consolidation reduces the overall number of components and simplifies the device architecture while maintaining the benefits of low backlash and friction.
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
The solution achieves low backlash and low friction, allowing for high backdrivability and efficient control in various modes, including shock-absorbing catching and high-speed grasping without external sensors, enhancing the robot hand's performance and versatility.
Implementation Method 1
a second magnetic gear configured to be magnetically engaged with the first magnetic gear
Data Source
AI summary
An actuator unit (1) includes a direct drive motor (2), a first magnetic gear (3) connected to a rotating shaft (6) of the direct drive motor (2), a second magnetic gear (4) configured to be magnetically engaged with the first magnetic gear (3), and a planetary reducer (5) connected to a rotating shaft of the second magnetic gear (4).