Movement Control Device for Inkjet Ejection
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Solution Overview
Problem
Inkjet image forming apparatuses face challenges in accurately stopping a moving unit at a target stop position due to mechanical loads such as torque unevenness and friction, leading to unstable movement and potential overshooting.
Innovation Solution
A movement control device with a detecting unit and a drive control unit that switches from speed control to position control based on the detected position and a threshold difference, ensuring the moving unit stops accurately at the target position by adjusting the PWM command value and using PI control to manage speed errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If speed control is used for the moving unit, then the moving unit can maintain uniform speed during movement, but the moving unit cannot be stopped accurately at the target stop position due to mechanical loads such as torque unevenness and friction
Solution Approach 1:
The control method dynamically switches between speed control and position control modes based on the movement phase. During uniform speed movement, speed control is used to maintain constant velocity. When approaching the target position, the system transitions to position control to achieve accurate stopping, thereby resolving the contradiction between maintaining uniform speed and achieving precise positioning.
Solution Approach 2:
The control parameters are changed based on the movement phase. The control system monitors the position and speed of the moving unit, and when the unit approaches the target position, it changes the control parameter from speed-based to position-based control, allowing accurate stopping despite mechanical loads like friction and torque unevenness.
2Reliability
If the moving unit stops before reaching the target stop position due to mechanical load, then the moving unit avoids overshooting, but the moving unit cannot be stopped at the target stop position
Solution Approach 1:
The control system continuously monitors the position and speed of the moving unit and uses this feedback to adjust the control strategy. When the moving unit approaches the target position, the feedback information triggers a switch to position control mode, which provides more precise control to ensure accurate stopping at the target position rather than stopping early or overshooting.
Solution Approach 2:
The control system prepares for the transition from speed control to position control in advance by monitoring approach to the target position. This preliminary detection allows the system to switch control modes at the optimal moment, ensuring that position control is active when needed for accurate stopping, thereby preventing both early stopping and overshooting.
3Manufacturing precision
If switching control from speed control to position control is implemented, then accurate stopping at target position is achieved, but control complexity increases
Solution Approach 1:
The control process is segmented into distinct phases: speed control phase for uniform movement and position control phase for precise stopping. This segmentation allows each control mode to be optimized for its specific function while keeping the overall system manageable through clear phase transitions based on position and speed thresholds.
Data Source
AI summary
A movement control device configured to determine whether the moving unit moved by a driving unit is in a stopped state at a position before a predetermined target stop position, and whether a difference between the detection position and the target stop position is equal to or smaller than a threshold difference, based on a detection position of the moving unit, after the moving unit starts deceleration operation, and switch a control of the driving unit to a position control based on the difference between the detection position and the target stop position, from a speed control based on a designated speed associated with the detection position to the target stop position, if the moving unit is in the stopped state at a position before the predetermined target stop position, and the difference is equal to or smaller than the threshold difference.