HCBC-2 Optical Encoder with Confocal Sensor Array for Alignment Error Reduction
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Solution Overview
Problem
Existing position encoders in precision industrial machines face challenges with measurement errors due to imperfect alignment and limited bandwidth, leading to inaccuracies and reduced sample rates, especially in multitrack optical absolute position encoding systems.
Innovation Solution
The development of Optical Absolute Linear and Rotary Position Encoders using a Hybrid Cyclic Binary Code-2 (HCBC-2) scale with a Confocal Optical Sensor Array, which enables simultaneous readout of all tracks, reducing measurement errors through automatic physical alignment and high temporal readout rates up to 1 MHz.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multitrack optical absolute position encoding is used, then measurement accuracy and operator safety are improved, but measurement errors arise due to imperfect alignment of readout mechanisms with respect to the measurement scale
Solution Approach 1:
The system uses alignment tracks with alignment markers that automatically detect and indicate misalignment conditions. The readout mechanism self-diagnoses alignment status by detecting the position of alignment markers on dedicated alignment tracks, enabling the system to identify and compensate for misalignment errors without external intervention.
Solution Approach 2:
The system incorporates alignment feedback through dedicated alignment tracks that provide continuous information about the relative position between the readout mechanism and measurement scale. This feedback enables real-time detection of misalignment and allows for corrective actions to maintain measurement accuracy.
2Productivity
If higher bandwidth position and velocity feedback is provided, then machine accuracy and speed are improved, but device complexity increases
Solution Approach 1:
The encoder system is segmented into functionally independent components: measurement tracks for position encoding, alignment tracks for maintaining readout accuracy, and velocity tracks for speed measurement. This segmentation allows each component to be optimized independently while working together to achieve high bandwidth feedback with improved machine performance.
Solution Approach 2:
The measurement scale serves multiple functions simultaneously: it provides position information through binary-coded tracks, velocity information through dedicated velocity tracks, and alignment reference through alignment tracks. This multi-functionality reduces the need for separate systems and minimizes overall device complexity while achieving high bandwidth feedback.
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 significantly reduces position errors and increases measurement sample rates, achieving high accuracy and improved machine performance by allowing nearly simultaneous readout of code bits across multiple tracks, thereby enhancing machine accuracy and speed.
Implementation Method 1
light rays generated in a Confocal Optical Sensor Array that impinge upon and are reflected to optical sensors by a Planar Hybrid Cyclic Binary Code-2 (HCBC-2) scale
Implementation Method 2
Confocal Optical Sensor Array
Data Source
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AI summary
Optical Position Encoders and methods using the same are described. In embodiments, the optical position encoders include a multitrack Hybrid Cyclic Binary Code-2 (HCBC-2) encoded scale and an Optical Readout Assembly (ORA), where the ORA provides absolute position optical readout and automatic physical alignment to the scale. Linear optical position encoders, rotary optical position encoders, and methods of measuring the position of ORA relative to a scale using such encoders are also described.