Actuator Pressure Simulation for Fault-Tolerant Position Control
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Solution Overview
Problem
Existing control valve systems are rendered inoperative due to failures in valve position feedback, limiting their application and requiring additional configuration and tuning for fault tolerance, especially when position sensors fail.
Innovation Solution
A method that employs a simulation model to provide simulated position feedback, allowing control of actuators without a position sensor, enabling fault-tolerant operation and expanding the range of applications by deriving actuator position from measured actuator pressure, using a dynamic simulation model that accounts for time-varying behavior and non-linear steady-state positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a position sensor is integrated to the valve positioner for feedback control, then the positioning accuracy is improved, but the system reliability deteriorates when the position sensor fails
Solution Approach 1:
The patent changes the feedback parameter from direct position measurement (via position sensor) to indirect position estimation (via simulation model using actuator pressure and control signals). This allows the system to maintain feedback control functionality even when the position sensor fails, resolving the contradiction between measurement precision and reliability.
Solution Approach 2:
The patent introduces a simulation model as an intermediary that estimates actuator position based on actuator pressure measurements and control signals. This intermediary provides a backup feedback mechanism that operates independently of the position sensor, maintaining system reliability when the primary position measurement fails.
2Reliability
If a secondary pressure feedback controller is added to back up the primary position feedback controller, then the system reliability is improved, but the device complexity increases
Solution Approach 1:
The patent makes the valve positioner multi-functional by enabling it to operate in multiple feedback modes (position sensor feedback, pressure feedback, and simulation-based feedback) using the same hardware platform. This eliminates the need for separate secondary controllers while maintaining fault tolerance, resolving the contradiction between reliability and device complexity.
Solution Approach 2:
The simulation model uses readily available data (actuator pressure measurements and control signals already present in the system) to generate position feedback, making the system self-sufficient and eliminating the need for additional dedicated backup controller hardware.
3Measurement precision
If a position sensor is required for feedback control, then the positioning precision is improved, but the adaptability of the actuator control system deteriorates
Solution Approach 1:
The patent changes the feedback approach from requiring direct position measurement to using simulation-based position estimation, enabling the control system to work with actuators that lack position sensors while maintaining positioning capability through alternative measurement parameters (actuator pressure).
Solution Approach 2:
The valve positioner is designed to support multiple actuator types and configurations (with or without position sensors, pneumatic or hydraulic actuators) by providing multiple feedback modes, thereby achieving universal applicability across different actuator designs without sacrificing positioning precision.
Data Source
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Figure 2A~2B
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AI summary
A controller (2) for controlling a pneumatic or hydraulic actuator (3) of a process device (1) comprises a position feedback signal input for receiving a measured position signal (hmeas) representing a position (h) of the actuator or the process device, an actuator pressure output (C1), and a pressure sensor (22) for measuring the actuator pressure (pactuator). The controller is configured to operate in a measured position feedback mode and a simulated position feedback mode. In the measured position feedback mode the actuator (3) is controlled dependent on a setpoint position (hsp) and the measured position (hmeas), and in the simulated position feedback mode the actuator is controller based on the setpoint position (hsp) and a simulated position (hsim) of the actuator or the process device. The simulated position (hsim) is derived from the measured actuator pressure (pactuator) by a simulation model (23).