Rotary Encoder Error Correction via Induced Voltage Compensation
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Solution Overview
Problem
Existing magnetic type rotary encoders face challenges in achieving high detection accuracy due to induced voltage errors, which are not adequately corrected by existing methods, leading to insufficient calculation accuracy of rotational speed and detection accuracy.
Innovation Solution
A rotary encoder design that includes a magnet and magnetic sensor parts generating 'A' and 'B' phase signals with a 90° phase difference, a control part that calculates the rotation position using these signals, and stores parameters for error correction based on reference rotation speeds to adjust for induced voltage errors, ensuring accurate detection regardless of rotation speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic type rotary encoder is used to detect rotation position, then the detection function is provided, but induced voltage generates error signals that deteriorate detection accuracy
Solution Approach 1:
The patent converts the harmful induced voltage signal into a useful correction signal. By detecting the induced voltage error component and using it to generate a correction value, the system transforms the harmful interference into a beneficial error compensation mechanism, thereby improving detection accuracy
Solution Approach 2:
The patent implements a feedback mechanism where the induced voltage error is detected, processed to generate a correction value, and then applied to correct the output signal. This closed-loop feedback approach continuously compensates for errors, maintaining high detection accuracy despite the presence of induced voltage
2Measurement precision
If correction method using stored correction amounts is used, then some error compensation is achieved, but calculation accuracy of rotational speed is insufficient leading to inadequate correction
Solution Approach 1:
The patent performs preliminary measurement and calculation of the induced voltage error component and correction values during a calibration phase. By pre-calculating correction amounts for different rotational speeds and storing them, the system ensures accurate correction is available when needed, eliminating the insufficiency of real-time calculation
3Measurement precision
If correction processing is implemented, then induced voltage errors are reduced, but device complexity increases due to additional control part functions
Solution Approach 1:
The control part is designed to perform multiple functions: it detects the induced voltage error component, calculates correction values, stores correction data, and applies corrections to output signals. By making the control part multi-functional, the patent avoids adding separate dedicated components for each function, thereby managing device complexity while achieving accurate error correction
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 solution provides a high degree of detection accuracy by correcting induced voltage errors and maintaining a constant output signal, improving the calculation accuracy of rotational speed and position detection.
Implementation Method 1
A magnetic type rotary encoder which utilizes a magneto-sensitive element such as a magneto-resistance effect (MR) element or a Hall element
Implementation Method 2
A magnetic type rotary encoder which utilizes a magneto-sensitive element such as a magneto-resistance effect (MR) element or a Hall element
Implementation Method 3
a magnet which is provided in one of the fixed body and the rotor body
Implementation Method 4
induced voltage is generated in a wiring line, a circuit and the like due to a change of a magnetic field accompanied with rotation of a rotor body (magnet)
Data Source
AI summary
A rotary encoder includes a control part having a storage section storing a plurality of parameters regarding error signal components at a reference rotation speed, the error signal components respectively being superposed on an “A”-phase signal and a “B”-phase signal in proportion to a rotation speed of a rotor body, and a rotation speed calculation section structured to measure a reception interval of a requirement signal and calculate a current rotation speed of the rotor body. The control part is structured to convert a parameter stored in the storage section to a value at the current rotation speed based on a ratio between the reference rotation speed and the current rotation speed, correction processing correcting the “A”-phase signal and the “B”-phase signal is executed based on the value converted, and the rotation position of the rotor body is calculated by using a corrected “A”-phase signal and a corrected “B”-phase signal.