Sheet Transport Control via Dual Roller Tension Feedback
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Solution Overview
Problem
Conventional sheet transporting systems face challenges in achieving high-precision control of sheet tension and state quantities, particularly with short sheets like standard paper, due to excessive load causing slippage between rollers, which complicates control of position, speed, and acceleration.
Innovation Solution
A transporting system with two rollers, each driven by a separate motor, uses measuring devices to monitor rotary motion and reaction forces, and a controller calculates control inputs to manage sheet tension and state quantities precisely by adjusting the driving signals for both motors, ensuring appropriate tension and speed control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional single-roller tension control is used, then the control system is simple, but high-precision control of sheet tension is difficult to achieve
Solution Approach 1:
The patent divides the tension control function across multiple rollers (send-out roller and transporting roller) rather than relying on a single roller. Each roller is equipped with its own driving device and measuring device, allowing independent control and measurement. This segmentation enables high-precision tension control by distributing the control function while maintaining system manageability through modular architecture.
Solution Approach 2:
The patent implements feedback control by measuring the rotary motion state quantities of both the send-out roller and transporting roller, comparing them with target values, and adjusting the driving devices accordingly. The controller continuously monitors the actual tension through the relationship between the two rollers' motion states and modifies their speeds to maintain desired tension, achieving high-precision control through closed-loop feedback.
2Speed
If excessive load is applied to transport short sheets, then the transporting speed can be maintained, but slippage occurs between rollers and sheet
Solution Approach 1:
The patent employs dynamic speed control of the rollers based on real-time measurement of their rotary motion state quantities. Instead of applying excessive static load, the system continuously adjusts the roller speeds to match the sheet's transport requirements. This dynamic adjustment ensures sufficient transporting speed while preventing slippage by optimizing the friction force at each moment based on actual conditions.
Solution Approach 2:
The patent changes the operating parameters (rotation speeds) of the rollers dynamically during the transport process. By measuring the state quantities and comparing with target values, the system adjusts the rotation speeds of both the send-out and transporting rollers to maintain optimal friction conditions, preventing slippage while ensuring adequate transport speed for short sheets.
3Productivity
If multiple rollers are used for sheet transport, then the transporting capability is improved, but the control of sheet tension becomes more difficult
Solution Approach 1:
The patent segments the tension control function across multiple rollers, with each roller having its own driving device and measuring device. This modular segmentation improves transporting capability by allowing independent optimization of each roller's function while keeping the control complexity manageable through distributed control architecture.
Solution Approach 2:
The patent uses feedback control to simplify multi-roller tension management. By measuring the rotary motion state quantities of all rollers and comparing them with target values, the controller automatically coordinates the speed adjustments of each roller to maintain proper tension relationships, reducing the complexity of manual multi-roller coordination.
Data Source
AI summary
There is provided a transporting system including two rollers to transport a sheet, two driving devices to drive the rollers, two measuring devices, and a controller to control the transport. The controller includes two estimating units to estimate values R1 and R2 related to reaction forces act on the rollers, a first calculating unit to calculate a control input U1, a second calculating unit to calculate a control input U2 in accordance with a deviation between a target value and (R1−R2)/2, first and second drive controllers to input a control signal in accordance with U1 and U2 to the first and second driving devices, and a setting unit. In an initial stage of a period in which the sheet is transported by the two rollers, the setting unit sets the target value to a value greater than that of the target value after the initial stage.