Inner Rotor Joint Structure for Backlash-Free Planar Robots
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Solution Overview
Problem
Traditional planar articulated robots face challenges in achieving high transmission accuracy and torque density due to backlash in harmonic or RV reducers, which affects assembly precision and speed requirements in modern manufacturing.
Innovation Solution
A planar articulated robot design incorporating a magnetic gear compound motor with a low-speed and high-speed rotor assembly, a magnetizing ring, and a stator core, where the magnetizing ring adjusts magnetic fields to generate spatial harmonics for torque and speed transmission, enhancing accuracy and reducing motor size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If harmonic reducer or RV reducer is used to drive the mechanical arm, then the robot can achieve high speed operation, but backlash between meshing teeth causes transmission errors and reduces assembly accuracy
Solution Approach 1:
The patent replaces the traditional mechanical reducer (harmonic or RV) with a magnetic gear transmission system. The magnetic gear uses magnetic fields between rotor magnets and stator magnets to transmit torque, eliminating physical meshing teeth and their associated backlash. This substitution maintains high speed capability while achieving high transmission accuracy suitable for precision assembly operations.
Solution Approach 2:
The patent changes the transmission mechanism from mechanical tooth-based engagement to magnetic field-based coupling. By altering the fundamental parameter of torque transmission from mechanical contact to magnetic interaction, the system eliminates backlash while maintaining high speed performance, thereby resolving the contradiction between speed and precision.
2Manufacturing precision
If magnetic gear compound motor is used instead of traditional reducer, then transmission accuracy is improved, but the structure becomes more complex
Solution Approach 1:
The patent merges the motor and magnetic gear transmission into a single integrated compound motor structure. The stator magnets are positioned within the motor stator, and rotor magnets are on the motor rotor, combining drive and transmission functions in one unit. This integration simplifies the overall structure by eliminating separate reducer components while maintaining high transmission accuracy through magnetic gear principles.
Solution Approach 2:
The magnetic gear compound motor performs multiple functions simultaneously: it provides electromagnetic torque generation like a traditional motor, and magnetic gear transmission for speed reduction and torque multiplication. This multi-functionality reduces the need for separate components, simplifying the overall system structure while achieving high transmission accuracy.
3Power
If traditional reducer is used, then the motor size can be larger, but the torque density is relatively small and the overall structure is less compact
Solution Approach 1:
The patent implements a nested structure where the stator magnets are positioned within the motor stator, and the rotor magnets are on the motor rotor, with the magnetic gear transmission fields nested within the motor's electromagnetic fields. This nested arrangement allows the transmission function to be embedded within the motor structure itself, increasing torque density and reducing overall volume compared to traditional motor-plus-reducer configurations.
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 design achieves high transmission accuracy, high permanent magnet utilization, and a compact structure with reduced motor volume, addressing the limitations of traditional robots by improving speed and torque density while maintaining low costs.
Implementation Method 1
the magnetizing ring adjusts magnetic fields to generate spatial harmonics for torque and speed transmission
Implementation Method 2
a magnetizing ring located between the low-speed rotor assembly and the high-speed rotor assembly in a circumferential direction
Implementation Method 3
a coil is wound around the stator core
Data Source
AI summary
The present invention discloses a planar articulated robot and an inner rotor joint device, including a base, a first inner rotor joint device provided on the base, a first mechanical arm driven by the first inner rotor joint device, and a manipulator connected to the first mechanical arm, wherein the first inner rotor joint device comprises a rotating shaft fixedly connected to the first mechanical arm and extending along a longitudinal axis, a low-speed rotor assembly located on an outer periphery of the rotating shaft, a high-speed rotor assembly located on an outer periphery of the low-speed rotor assembly, a magnetizing ring located between the low-speed rotor assembly and the high-speed rotor assembly in a circumferential direction, a stator core located on an outer periphery of the high-speed rotor assembly with a certain gap therebetween in the circumferential direction, and a casing covering an outer periphery of the stator core and fixedly connected to the stator core, and a coil is wound around the stator core. The present invention enables high transmission precision, high utilization rate of permanent magnets, simple and compact structure, and low cost.