Absolute Encoder Analog Signal Normalization
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Solution Overview
Problem
Existing absolute encoder devices face limitations in achieving high precision and resolution due to the requirement for custom sensors and increased complexity and cost, especially when trying to use commercially available sensors, which are often too large for high resolution applications.
Innovation Solution
The use of sensors equally distributed on a circular path that provide analog output, with a rotating disc having sections of different properties, allowing for high absolute resolution through analog signal normalization and processing to generate digital codes, eliminating the need for additional patterned tracks and custom sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If absolute encoder devices use a high number of sensors to achieve high resolution, then measurement precision is improved, but device complexity and cost increase due to requirement for custom sensors
Solution Approach 1:
The patent changes the output parameter type of sensors from digital to analog, allowing continuous position information to be obtained. This enables high resolution without increasing sensor count, as analog signals provide infinite resolution potential compared to discrete digital values
Solution Approach 2:
The patent transitions from one-dimensional digital encoding (limited by sensor count) to two-dimensional measurement by combining analog signal amplitude with temporal processing. The analog output dimension adds continuous resolution capability beyond what discrete sensor counts can provide
2Measurement precision
If absolute encoder devices use more sensors to increase resolution, then measurement precision is improved, but manufacturing cost increases due to custom sensor requirements
Solution Approach 1:
The patent employs inexpensive, commercially available analog sensors instead of expensive custom digital sensors. The approach uses off-the-shelf components that can be easily manufactured and replaced, significantly reducing per-unit cost while maintaining high resolution through analog processing
Solution Approach 2:
By changing from digital to analog sensor output, the patent enables use of mass-produced, low-cost analog sensors rather than requiring expensive custom digital sensors. This parameter change fundamentally alters the cost structure while preserving measurement capability
3Measurement precision
If sensors are placed close together to achieve high resolution with fewer sensors, then measurement precision is improved, but ease of operation deteriorates due to difficulty in sensor placement and calibration
Solution Approach 1:
The patent employs dynamic signal processing to compensate for static placement variations. By processing analog signals temporally and mathematically, the system can achieve high resolution even with sensors placed at non-ideal positions, making the system tolerant of manufacturing tolerances and simplifying installation
Data Source
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AI summary
The device to measure the absolute rotation angle of a rotating shaft includes a rotating disc, fixed to the shaft. A group of permanent magnets of different sizes and polarities is disposed on a circular track. Further, a group of Hall sensors, fixed to a static part of the device, are disposed on a circular path, in proximity of the rotating disc magnets tracks, and generate electric signals proportional to the strength of the magnetic field produced by the magnets in proximity. The signs of these electric signals are used to calculate a code characteristic of a low resolution absolute angular position. Two analog signals are associated to the obtained code, according to a pre-defined table. The associated analog signal having the closest value to zero is used as an entry to a pre-recorded table containing the correspondent angular position of the shaft.