Hydraulic Valve Stroke Control Using Dynamic Flow Force Estimation
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Solution Overview
Problem
Existing control devices for hydraulic systems face increased stroke distance estimation errors due to reliance on static equilibrium conditions, leading to inaccurate control of valve body movement.
Innovation Solution
A control device that calculates a stroke command based on an input opening command and estimates dynamic deviations and flow forces, using a stroke command calculator, observer, and flow force estimator to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If stroke distance is estimated primarily on the basis of only the static equilibrium conditions for the spool, then the control method is simple, but the stroke distance estimation error increases
Solution Approach 1:
The patent transitions from static equilibrium conditions to dynamic conditions by introducing an observer that estimates dynamic deviation of the spool stroke. The observer calculates dynamic deviation based on the difference between commanded stroke and actual stroke, then uses this dynamic information to correct the stroke command, thereby improving estimation accuracy while accounting for dynamic system behavior.
Solution Approach 2:
The patent implements feedback control by using the estimated dynamic deviation to correct the stroke command. The flow force estimator receives the corrected stroke command and feeds back the estimated flow force to the stroke command calculator, creating a closed-loop system that continuously refines the stroke command based on actual system behavior, reducing estimation errors.
2Measurement precision
If a sensor circuit is used to perform feedback control on spool position, then control accuracy is improved, but the system complexity and cost increase
Solution Approach 1:
The patent creates a virtual model (copy) of the spool position by using an observer to estimate the dynamic deviation based on commanded stroke and system parameters. This estimated position information serves as a substitute for physical sensor measurements, allowing feedback control to be performed without actual sensors, thereby reducing system complexity and cost while maintaining control accuracy.
Solution Approach 2:
The patent replaces the mechanical sensor circuit with a computational observer that uses mathematical models and calculations to estimate spool position. The observer substitutes physical measurement devices with algorithm-based estimation, eliminating the need for additional hardware sensors while achieving the same feedback control function.
Data Source
AI summary
This control device controls movement of a valve body of a valve device included in a hydraulic system and includes: a stroke command calculator that calculates a stroke command for the valve body on the basis of an opening command that is input to the stroke command calculator; an observer that estimates, on the basis of the stroke command, a dynamic deviation of a stroke of the valve body that corresponds to the stroke command; and a flow force estimator that estimates, on the basis of the stroke command and the dynamic deviation, a flow force acting on the valve body. The stroke command calculator calculates the stroke command on the basis of the flow force in addition to the opening command.