Loop-Powered Pneumatic Interface Self-Calibration
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Solution Overview
Problem
Existing process control systems using pneumatic devices face accuracy issues and high costs due to the need for external high-voltage power sources, which also complicate hazardous area certifications.
Innovation Solution
A loop-powered pneumatic process control device interface that scavenges power from a low-voltage control signal to operate an actuator, using a calibrator to adjust the set point based on positional feedback, eliminating the need for external high-voltage power and enhancing accuracy and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If external high-voltage power sources are employed to power a motor or electromechanical actuator for set point adjustments, then the actuator can be powered, but the cost and complexity increase and hazardous area certifications are prevented
Solution Approach 1:
The pneumatic controller performs its own calibration using its existing loop power and internal components. The system scavenges power from its own control signal and uses its own processor and output mechanisms to execute calibration routines, eliminating the need for external calibration equipment and high-voltage power sources.
Solution Approach 2:
The pneumatic controller is designed to perform multiple functions: process control, self-calibration, and self-powering. The same processor that controls the process also executes calibration routines, and the same loop power that operates the controller also powers the calibration actuator, reducing the need for dedicated calibration hardware.
2Ease of operation
If intermediate transducers are employed to convert electrical signals to pneumatic signals, then set point changes can be transmitted, but accuracy is reduced
Solution Approach 1:
The system uses feedback from the actual position of the set point input to detect calibration errors. The processor compares the commanded position with the actual position and adjusts the output signal accordingly to eliminate positioning errors, ensuring accurate control without intermediate transducers.
Solution Approach 2:
The patent replaces mechanical intermediate transducers with an electronic feedback system. Instead of using mechanical signal conversion devices that introduce accuracy losses, the system uses electronic sensing of the actual position and electronic adjustment of the control signal to achieve precise control.
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
The solution provides accurate and cost-effective control of pneumatic process devices while meeting hazardous area certification requirements by using low-power actuation and feedback-based calibration, reducing complexity and power consumption.
Implementation Method 1
a power input to scavenge power from a loop power control signal associated with the process control system
Implementation Method 2
a calibrator to read position feedback of the actuator during the movement to calculate a positional error
Data Source
AI summary
Adjustment of loop-powered pneumatic process control device interfaces is disclosed. A disclosed example interface for use with a pneumatic process control device includes a power input to scavenge power from a loop power control signal associated with the process control system, a movement controller to cause movement of an actuator powered by the loop power, where the actuator is operatively coupled to a movable control input associated with the process control device, and a calibrator to read position feedback of the actuator during the movement to calculate a positional error, where the calibrator is to adjust a set point of the loop power control signal based on the positional error to control the actuator.