Magnetic Encoder for Robot Shaft Rotation Detection
Solution Overview
Problem
Existing driving devices for industrial robots and machine tools face challenges in accurately detecting the rotation of output shafts due to shaft shaking and the need for multiple encoders, which increases size and cost.
Innovation Solution
The implementation of an encoder system with a first and second detection unit, integrated into a single control board, that uses a scale and index portions to accurately detect relative rotations between rotating members, allowing for high-accuracy detection of motor and reducer rotations while reducing device size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a long output shaft is provided in the reducer, then the transmission ratio can be achieved, but shaft shaking occurs at the tip end portion resulting in poor rotation detection accuracy
Solution Approach 1:
The patent uses a magnetic encoder that creates a magnetic field pattern as a copy of the rotational position information. Instead of mechanically detecting the long output shaft's rotation, the magnetic encoder generates a magnetic field distribution that replicates the rotational state, allowing accurate detection without being affected by shaft shaking. The magnetic field serves as an informational copy of the rotation that can be read remotely.
Solution Approach 2:
The patent replaces mechanical contact-based rotation detection with a magnetic field-based detection system. The magnetic encoder uses magnetic fields instead of mechanical linkages or contact sensors, eliminating the transmission of mechanical vibrations and shaking to the detection mechanism. This substitution of mechanical detection with magnetic field detection resolves the shaft shaking problem.
2Measurement precision
If multiple encoders are mounted on different shafts to detect rotation accurately, then positioning accuracy improves, but device size and cost increase
Solution Approach 1:
The patent implements a single magnetic encoder that simultaneously performs multiple detection functions. The encoder detects both the motor shaft rotation and the output shaft rotation by utilizing the magnetic coupling through the reducer. This multi-functional approach allows one encoder to replace what would traditionally require multiple separate encoders, reducing device complexity while maintaining positioning accuracy.
Solution Approach 2:
The patent merges the detection of multiple shaft rotations into a single magnetic encoder system. By combining the motor shaft and output shaft detection capabilities into one integrated magnetic encoder, the system reduces the number of separate detection units needed. The magnetic encoder effectively consolidates multiple detection functions that would otherwise require separate encoders mounted on different shafts.
Data Source
AI summary
An encoder includes: a first scale which has a first index portion; a second scale which has a second index portion; a first detection unit which outputs a first signal based on the first index portion, regarding first relative rotation between a fixing member and a first rotating member; a second detection unit which outputs a second signal based on the second index portion, regarding second relative rotation between the fixing member and a second rotating member; and a signal-processing unit which calculates information regarding the first relative rotation on the basis of the first signal and which calculates information regarding the second relative rotation on the basis of the second signal.