Encoder Delay Compensation Filter for Stable Angle Measurement
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Solution Overview
Problem
Digital encoders used in manufacturing robots face challenges in accurately determining the position of a rotating object due to propagation delay in signal processing, leading to instability and limited dynamic range in existing compensation methods.
Innovation Solution
A propagation delay compensation circuit is introduced, comprising a series of low pass filters and differentiators to calculate noise-reduced angular speed and acceleration, which are then used in a delay compensator to calculate a propagation delay compensated digital output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a parallel two filter circuit with feedback loop is used to compensate propagation time delay, then the angle position accuracy is improved, but the system becomes unstable and limited in dynamic range
Solution Approach 1:
The patent replaces the mechanical feedback loop system with an electronic signal processing system. Instead of using a parallel two filter circuit with feedback that causes instability, the invention uses a single filter circuit that processes the signal through multiple stages (filtering, differentiation, integration) to compensate for propagation delay. This substitution of the feedback mechanism with a direct signal processing approach eliminates the instability while maintaining angle position accuracy.
2Measurement precision
If a parallel two filter circuit with feedback loop is used to compensate propagation time delay, then the angle position accuracy is improved, but the dynamic range is limited
Solution Approach 1:
The patent implements a dynamic signal processing system where the filter circuit adapts to different operating conditions. The system uses variable filtering parameters and dynamic signal processing techniques that allow it to maintain accuracy across a wide dynamic range. The filter circuit can adjust its response based on the input signal characteristics, enabling it to handle both small and large angle positions accurately without the limitations of a fixed feedback loop system.
3Measurement precision
If noise reduction filtering is applied to the digital input signal, then the measurement precision is improved, but the propagation delay increases
Solution Approach 1:
The patent applies noise reduction filtering as a preliminary action before the signal enters the main processing path. By pre-filtering the digital input signal, the system reduces noise early in the processing chain, which improves measurement precision without adding significant delay to the critical measurement path. The filtered signal is then processed through differentiation and integration stages that compensate for any remaining propagation delay.
Data Source
AI summary
Various embodiments provide a filter for propagation delay compensation and interpolation in encoder digital signal processing. The filter can include a first low pass filter configured to reduce noise of a digital input comprising a measured angular position; a first differentiator configured to receive a filtered digital input and to calculate a speed from a difference in time of the measured angular position and a previous angular position; a second low pass filter configured to reduce noise from the speed; a second differentiator configured to receive a filtered speed and to calculate acceleration using a difference in time of the filtered speed and a previous speed; a third low pass filter configured to reduce noise of the acceleration; and a delay compensator configured to receive the filtered digit input, the filtered speed, and a filtered acceleration, and to calculate a propagation delay compensated digital output.