Valve Control Device Hysteresis Correction Logic
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Solution Overview
Problem
Liquid pressure control devices face hysteresis issues when controlling the flow rate of linear control valves, leading to inaccurate valve control, especially during transitions from increasing to reducing control outputs, which can result in the actual opening degree not reaching the target.
Innovation Solution
A valve control device with a correction unit that accounts for hysteresis by forbidding corrections until the difference between the control output and actual output values falls within a predetermined range, ensuring accurate control by suppressing unnecessary corrections and aligning the output with the target.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hysteresis correction is continuously applied to control the linear control valve, then the valve opening degree can be adjusted, but unnecessary corrections occur during transitions causing the actual opening degree to deviate from the target
Solution Approach 1:
The control device applies preliminary anti-action by detecting transitions in the increasing/reducing direction of the control output value and temporarily suspending hysteresis correction during these transition periods. This prevents the harmful effect of unnecessary corrections that would otherwise cause the actual valve opening degree to deviate from the target, while resuming correction after the transition completes to restore control precision.
2Speed
If feed-forward control is used to set the control output, then the response speed is improved, but the actual opening degree may not reach the target due to hysteresis
Solution Approach 1:
The control device combines feed-forward control with feedback mechanisms by continuously monitoring the actual valve opening degree and comparing it with the target opening degree. When the difference exceeds a predetermined threshold, the system adjusts the control output to compensate for hysteresis effects, ensuring the actual opening degree reaches the target while maintaining the fast response characteristics of feed-forward control.
3Measurement precision
If hysteresis correction is applied immediately after direction switching, then control precision is improved, but unnecessary corrections occur before the actual output stabilizes
Solution Approach 1:
The control device performs preliminary action by detecting the increasing/reducing direction of the control output value and preparing for hysteresis correction in advance. When a transition is detected, the system temporarily suspends correction until the actual output stabilizes within an acceptable range, then resumes correction to improve precision without introducing unnecessary complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively brings the output of the linear control valve closer to the target, ensuring accurate control and responsiveness in both feedback and feed-forward control scenarios, thereby improving the precision and performance of the liquid pressure control device.
Implementation Method 1
hysteresis is present between the increasing control characteristics when changing the control output (for example, a target current value) to increase the flow rate
Data Source
AI summary
A valve control device includes a correction unit that corrects hysteresis in output of a control valve according to an increasing/reducing direction of a control output value; a detection unit configured to detect an actual output value to the control valve corresponding to the control output value; and a forbidding unit configured to forbid correction by the correction unit, until a difference between the control output value and the actual output value becomes within a predetermined range, after the increasing/reducing direction of the control output value is switched.