Position Feedback Prediction for Motor Synchronicity
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Solution Overview
Problem
In motor control systems, especially in printing applications, the lack of synchronicity between multiple motors due to factors like non-uniform motor inertia and asynchronous position feedback updates leads to position errors, resulting in unacceptable product quality and increased waste.
Innovation Solution
A position feedback device with a prediction unit is implemented, which includes a comparator and counter to generate position values at predetermined intervals, allowing for accurate prediction of motor position between updates by using a subset of prior position values and misalignment calculations, thereby aligning position signals and improving precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If position feedback updates are performed at predetermined intervals using counters, then device complexity is reduced and ease of operation is improved, but measurement precision deteriorates because position data becomes stale between updates
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing position values at predetermined update intervals using a counter, then using these pre-computed values to predict intermediate positions. This allows the system to provide accurate position data at any moment without requiring continuous complex measurements, as the prediction unit can interpolate between pre-calculated positions based on the misalignment between request timing and update intervals.
2Productivity
If asynchronous position feedback updates are used to improve productivity, then position errors increase due to misalignment between feedback updates and position requests
Solution Approach 1:
The patent implements feedback by continuously monitoring the misalignment between the actual time of position requests and the predetermined update intervals. The prediction unit uses this feedback information about timing differences to calculate corrected position values that compensate for the asynchronous nature of the updates, thereby maintaining manufacturing precision while allowing high-speed asynchronous operation.
Solution Approach 2:
The system dynamically adjusts the position parameter by predicting intermediate positions based on the misalignment between request timing and update intervals. Instead of using fixed position values from predetermined intervals, the system changes the position parameter to reflect the actual intermediate position at any given moment, maintaining precision despite asynchronous updates.
3Measurement precision
If position feedback is updated continuously at high frequency, then measurement precision is improved, but loss of energy increases due to higher processing requirements
Solution Approach 1:
The patent uses periodic action by updating position feedback at predetermined intervals rather than continuously. The counter generates position values at specific intervals, and the prediction unit interpolates between these periodic updates to provide accurate position data on demand. This periodic approach maintains measurement precision while significantly reducing processing energy consumption compared to continuous high-frequency updates.
Data Source
AI summary
An apparatus for use with an encoder feedback device includes a comparator, a counter, and a prediction unit. The encoder feedback device is coupled to rotate with a rotating load and operable to generate at least one feedback position signal indicative of movement of the rotating load. The comparator is operable to receive the feedback position signal and generate a first position signal including a plurality of edges based on the feedback position signal. The counter is operable to receive the first position signal and count the edges to periodically generate position values at a predetermined update interval. The prediction unit is operable to receive a position data request at a first time and predict a position of the rotating load at the first time as a function of at least a subset of the position values generated prior to the first time and a misalignment between the first time and the predetermined update interval to generate an aligned position signal.