Absolute Encoder Signal Processing for Higher Resolution
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Solution Overview
Problem
Existing absolute encoder devices face limitations in achieving high resolution and precision due to practical implementation challenges, such as limited resolution of analog sensors and digital codes, which are inefficient when increasing the number of sensors, leading to high costs and complexity.
Innovation Solution
A high-resolution encoder device with sensors equally distributed on a circular line, utilizing an auxiliary unit and advanced signal processing to provide a low-resolution position value that combines with digital code outputs, allowing for increased total resolution beyond the limitations of the number of sensors, and reducing sensitivity to mechanical and electronic tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of sensors is increased to achieve higher resolution, then the encoder resolution improves, but the device complexity and cost increase
Solution Approach 1:
The patent changes the parameter of signal processing by combining multiple sensor outputs through mathematical operations (addition, subtraction, multiplication by coefficients) to generate code values. This allows achieving higher resolution (e.g., 2048 positions per turn with 5 sensors) without increasing the number of sensors, thus resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The patent transitions from direct spatial resolution (number of sensors) to computational resolution (signal processing dimension). By processing sensor signals through multiple mathematical combinations and selecting optimal code values, the system achieves resolution beyond the physical sensor count, effectively adding a computational dimension to overcome the physical limitation
2Measurement precision
If the number of sensors is increased to achieve higher resolution, then the encoder resolution improves, but the cost increases
Solution Approach 1:
The patent changes the parameter of signal processing to achieve high resolution using a fixed small number of sensors (e.g., 5 sensors providing 2048 positions per turn). This eliminates the need to purchase and install numerous expensive sensors, thereby reducing manufacturing cost while maintaining high encoder resolution
Solution Approach 2:
The patent creates multiple code values from a single set of sensor readings through mathematical processing. Instead of using one sensor per position, the system generates multiple potential code values and selects the most appropriate one, effectively copying information to achieve higher resolution without additional sensors
3Measurement precision
If analog sensor resolution is limited, then the encoder precision is constrained, but increasing sensor count to compensate increases complexity
Solution Approach 1:
The patent performs preliminary mathematical processing of sensor signals to generate multiple code values before final selection. By pre-calculating various combinations of sensor outputs with different weights and coefficients, the system prepares multiple candidate code values that can be selected based on which provides the highest precision, thereby compensating for limited analog sensor resolution without increasing complexity
Solution Approach 2:
The patent changes the precision through signal processing parameters rather than hardware parameters. By adjusting the mathematical combinations (addition, subtraction, multiplication by coefficients like 0.5, 0.25) and selecting from multiple generated code values, the system achieves high encoder precision despite limited analog sensor resolution, avoiding the need for more complex sensor configurations
Data Source
AI summary
A high resolution encoder device using a number of static sensors distributed on a circumference, and a rotating disc, having several sections of two different properties on an annular track according to a predefined pattern, placed so that the sensors can sense the properties of the sections of track in proximity. An auxiliary unit is also provided and by itself or in combination with the sensor signal values, provides a first low resolution position value. In a first processing step, the signals of each sensor are compared to a threshold, and bit values zero or one for each sensor are set according to the comparison result. All bits are then set in a digital word, in order to create a code number, which in combination with the output of the auxiliary unit, is characteristic of a first low resolution position value. For each low resolution position value, a mathematical combination of signals values is defined. The values of the result of said mathematical combination of the signals value is then used as an entry variable to pre-recorded tables to output high resolution position value.