Arc-Motion Encoder Layout With Separated Tracks for Precise Measurement
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Solution Overview
Problem
Existing measuring instruments face challenges in achieving a desirable combination of compact size, high resolution, accuracy, and robustness to contamination, particularly in encoders used for arc motion measurements.
Innovation Solution
The measuring instrument incorporates a movable encoder portion with a detector and scale portion configured to measure absolute relative positions using a movable encoder that rotates in an arc motion, utilizing a field generating portion to generate changing magnetic flux and a sensing portion to detect position, with separate track portions and signal processing to correct for radial offsets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single encoder track is used for arc motion measurement, then the device structure is simple, but the resolution and accuracy are insufficient
Solution Approach 1:
The encoder is divided into multiple separate tracks (first track with first sensing elements and second track with second sensing elements), each track providing independent measurement capability. This segmentation allows each track to contribute to overall measurement precision while maintaining manageable structural complexity through modular design
Solution Approach 2:
The patent transitions from a single-dimensional encoder track to a multi-dimensional encoder structure with multiple tracks arranged at different radial distances from the pivot portion. This dimensional expansion enables simultaneous measurement of arc motion and radial position, thereby improving resolution without proportionally increasing complexity
2Volume of moving object
If the encoder tracks are close together to reduce size, then the device becomes more compact, but radial offset errors increase
Solution Approach 1:
The patent employs signal processing that uses detector signals from multiple tracks to determine relative position, with the system automatically compensating for radial offsets through computational correction. This feedback mechanism allows tight track spacing for compactness while maintaining manufacturing precision through software-based offset correction
Solution Approach 2:
The patent changes the measurement parameter approach by using multiple radial distances (RD1 and RD2) from the pivot portion to create tracks at different positions. This parameter variation allows the system to measure both arc motion and radial displacement, improving overall precision while the signal processing corrects for any residual radial offset errors
3Reliability
If traditional encoders are used, then the structure is simple, but robustness to contamination is insufficient
Solution Approach 1:
The patent replaces traditional mechanical contact-based encoders with an electromagnetic field-based detection system. The field generating portion creates electromagnetic fields that interact with signal modulating elements, and the sensing elements detect these field interactions. This substitution eliminates mechanical contact points that are susceptible to contamination, thereby improving reliability while the multi-track configuration manages complexity through distributed sensing
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 enhances the measuring instrument's performance by improving compactness, resolution, and robustness to contamination, enabling precise measurements in arc motion applications.
Implementation Method 1
a field generating portion configured to generate changing magnetic flux in response to drive signals
Data Source
AI summary
A measuring instrument includes a movable portion configured to rotate in an arc motion about a pivot portion, and an electronic position encoder configured to measure an absolute relative position between a detector portion and a scale portion, one of which forms part of the movable portion. A maximum movement range of the movable encoder portion is less than 360 degrees. In the scale portion, first and second scale element portions are arranged with central reference points at first and second radial distances RD1 and RD2, respectively, from the pivot portion, for which the ratio of RD1/RD2 is at least 1.4. In various implementations, a separation distance between first and second scale tracks (which include the respective scale element portions) is greater than the first scale track width and the second scale track width.