Encoder Absolute Position Error Detection via Segmented Comparison
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Solution Overview
Problem
Conventional electromagnetic induction type absolute encoders struggle to calculate synthesized absolute positions in a timely manner at high speeds, limiting the reliability of measurement values.
Innovation Solution
An encoder configuration that includes a reading device, a control device, and an output device, with a relative position comparison unit to detect and output errors between multiple incremental patterns, even at high speeds, and an absolute position comparison unit to verify calculated absolute positions, enhancing measurement reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the encoder calculates synthesized absolute position based on multiple incremental patterns, then measurement reliability is improved through error detection, but calculation time increases and high-speed measurement capability deteriorates
Solution Approach 1:
The patent segments the error detection function into two independent units: an absolute position comparison unit that compares calculated absolute position with synthesized absolute position, and a relative position comparison unit that compares relative positions from different incremental patterns. This segmentation allows parallel processing of error detection tasks, reducing overall calculation time while maintaining comprehensive error detection capability, thus resolving the contradiction between measurement reliability and high-speed measurement capability
Solution Approach 2:
The patent performs preliminary calculation of relative positions from multiple incremental patterns before the high-speed measurement phase. By pre-calculating and storing these relative positions, the system can quickly compare them during high-speed operation without performing full synthesized absolute position calculations, enabling both reliable error detection and high-speed measurement capability
2Reliability
If the encoder performs comparison operation between calculated absolute position and synthesized absolute position, then error detection capability is improved, but processing time increases and productivity decreases
Solution Approach 1:
The patent divides the comparison operation into two separate, parallel comparison units: absolute position comparison unit and relative position comparison unit. Each unit handles a specific type of comparison independently, allowing simultaneous execution without sequential delays. This segmentation enables comprehensive error detection while maintaining high processing speed, resolving the contradiction between error detection capability and processing speed
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 configuration allows for improved measurement value reliability by detecting errors between relative positions and calculated absolute positions, even at high speeds, and provides accurate error detection when relative positions are shifted, thereby enhancing the encoder's performance.
Implementation Method 1
The electromagnetic induction type encoder detects a relative movement amount of the head to the INC pattern from change in magnetic flux detected by the receiving coil via the scale coil when the transmitting coil is excited
Data Source
AI summary
An encoder includes: a reading device that reads respective electric signals from two incremental patterns respectively having graduation array pitches different from each other; a control device that calculates a measurement value, based on the electric signals; and an output device that outputs the measurement value. The control device includes: an absolute position synthesis unit that synthesizes two electric signals to generate a synthesized absolute position; a detection unit that detects two relative positions from the two electric signals; a position calculation unit that performs an arithmetic operation between the relative positions and the synthesized absolute position to calculate a calculated absolute position; an absolute position comparison unit that compares the calculated absolute position with the synthesized absolute position; and a relative position comparison unit that compares the two relative positions with each other. The output device outputs error information, based on a comparison result output from the control device.