Belt Steering Roll Feed-Forward Control for Tracking Errors
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Solution Overview
Problem
Media handling systems, particularly in printing systems, face challenges in accurately registering images due to registration errors caused by disturbances and the limitations of existing control techniques, such as feedback and feedforward control, which often result in overcompensation and position errors.
Innovation Solution
The implementation of a feedforward control system using a belt steering roll with a selectively tiltable axis of rotation, where the steering angle is adjusted based on a differential between the currently detected lateral position and a predetermined position, derived from a calibration or adaptive tuning process, to induce a lateral shift profile and correct belt edge position deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedforward control is used to anticipate known system disturbances, then response lag is eliminated and image quality improves, but belt steering actuators cause induced disturbance to the belt leading to position tracking errors and overcompensation
Solution Approach 1:
The patent implements feedback control by using edge sensors to detect the actual lateral position of the belt edge and comparing it with the target position. The controller adjusts the steering actuator based on this feedback to eliminate positioning errors and prevent overcompensation, directly resolving the contradiction between responsive control and positioning precision.
Solution Approach 2:
The patent changes the control parameter from open-loop feedforward commands to closed-loop feedback adjustments. By continuously monitoring the belt edge position and adjusting the steering actuator based on real-time feedback, the system eliminates the induced disturbances and positioning errors that occur with pure feedforward control.
2Ease of operation
If steering actuators are used to control lateral movement, then belt position can be adjusted, but induced disturbance to the belt causes position tracking errors
Solution Approach 1:
The patent uses edge sensors to provide feedback on the actual lateral position of the belt edge. This feedback loop allows the controller to detect and correct the induced disturbances caused by the steering actuator, maintaining both ease of operation and positioning precision simultaneously.
Solution Approach 2:
The patent performs preliminary calibration to establish the relationship between steering actuator commands and actual belt position. This preliminary action allows the system to anticipate and compensate for induced disturbances, maintaining accuracy while preserving operational ease.
3Manufacturing precision
If closed-loop feedback control is used to correct disturbances, then registration errors are addressed, but response lag occurs and quick or transient disturbances are not fully compensated
Solution Approach 1:
The patent implements preliminary calibration to establish the steering actuator's response characteristics and the belt's movement profile in advance. This preliminary action enables the controller to anticipate disturbances and pre-adjust the steering actuator, eliminating response lag while maintaining registration accuracy.
Solution Approach 2:
The patent dynamically adjusts the steering actuator based on real-time feedback from edge sensors. By continuously monitoring belt edge position and making real-time adjustments, the system eliminates both response lag and registration errors, resolving the contradiction between speed and precision.
Data Source
AI summary
An apparatus including a transfer belt, an edge sensor and a belt steering roll. The transfer belt having a lateral edge and the edge sensor detecting lateral positions of the lateral edge as it passes the edge sensor. The belt steering roll controlling lateral movement of the transfer belt, which is rotatably mounted maintaining rolling engagement with the transfer belt. An axis of rotation of the belt steering roll selectively tiltable defining a steering angle with respect to an axis reference orientation. Changes in the steering angle inducing a lateral shift profile to the lateral edge. The lateral shift profile defined by changes to the lateral positions of the lateral edge during a period. The steering angle being changed based on a differential between a currently detected lateral position of a segment of the lateral edge and a predetermined lateral position derived from the lateral shift profile.