Abstract: Techniques for diagnosing failures in a digital solenoid I/P converter are provided herein. A controller of the I/P converter may apply a fixed voltage to an I/P coil of the I/P converter, causing an armature to move from an off-position to an on-position in a properly-functioning I/P converter. The controller may receive an indication of whether a digital logic line trip has occurred, indicating that a current for the I/P coil has reached a desired maximum current level. The controller may remove the fixed voltage applied to the I/P coil when the maximum current level is reached or when a threshold period of time has elapsed from the application of the fixed voltage to the I/P coil. The controller may diagnose, based on whether the digital logic line trip occurred prior to removing the fixed voltage, a failure in the I/P converter.

Abstract: Techniques for diagnosing failures in a digital solenoid I/P converter are provided herein. A controller of the I/P converter may apply a fixed voltage to the I/P converter, causing an armature to move from an off-position to an on-position in a properly-functioning I/P converter. The controller may receive an indication of whether a digital logic line trip has occurred, indicating that a current for the I/P coil has reached a desired maximum current level, and an elapsed time from the application of the fixed voltage. The controller may compare the amount of time elapsed from the application of the fixed voltage to an expected amount of elapsed time from the application of the fixed voltage to the I/P coil after which a digital logic line trip will occur for a properly functioning I/P coil and diagnose, based on the comparison, a failure in the I/P converter.

Abstract: Methods and apparatus for quantifying pneumatic volume usage via valve controllers are disclosed. An example apparatus includes a valve controller operatively couplable to a pneumatic actuator, the pneumatic actuator being operatively coupled to a control valve. In response to an input signal indicating that a flow control member of the control valve is to be moved in a specified direction, the valve controller commands a current-to-pressure (I/P) converter of the valve controller to pulse a relay valve of the valve controller between a closed position and an open position. The pulsing of the relay valve causes the pneumatic actuator to move the flow control member in the specified direction. The valve controller calculates a pneumatic volume usage associated with the moving of the flow control member in the specified direction. The pneumatic volume usage is based on the pulsing of the relay valve.

Abstract: Techniques for diagnosing failures in a digital solenoid I/P converter are provided herein. A controller of the I/P converter may apply a fixed voltage to an I/P coil of the I/P converter, causing an armature to move from an off-position to an on-position in a properly-functioning I/P converter. The controller may receive an indication of whether a digital logic line trip has occurred, indicating that a current for the I/P coil has reached a desired maximum current level. The controller may remove the fixed voltage applied to the I/P coil when the maximum current level is reached or when a threshold period of time has elapsed from the application of the fixed voltage to the I/P coil. The controller may diagnose, based on whether the digital logic line trip occurred prior to removing the fixed voltage, a failure in the I/P converter.

Abstract: Techniques for diagnosing failures in a digital solenoid I/P converter are provided herein. A controller of the I/P converter may apply a fixed voltage to the I/P converter, causing an armature to move from an off-position to an on-position in a properly-functioning I/P converter. The controller may receive an indication of whether a digital logic line trip has occurred, indicating that a current for the I/P coil has reached a desired maximum current level, and an elapsed time from the application of the fixed voltage. The controller may compare the amount of time elapsed from the application of the fixed voltage to an expected amount of elapsed time from the application of the fixed voltage to the I/P coil after which a digital logic line trip will occur for a properly functioning I/P coil and diagnose, based on the comparison, a failure in the I/P converter.

Abstract: A control loop for a double-acting pneumatic actuator is configured to generate two control signals, one for each of the two pneumatic chambers for the purpose of controlling the actuator position in view of operating constraints on the chamber pressures or the stiffness of the actuator. A numerical indicator of the stiffness may be computed in a variety of ways, for example, as the average of the two chamber pressures. In one embodiment a numerical indicator of stiffness is treated as an output of the system along with the position of the actuator. A multi-input multi-output control loop with position and pressure feedback may be used to simultaneously control the position and the stiffness of the actuator.

Abstract: Systems and methods may be provided to digitally control both position and crossover pressure in a double-acting pneumatic actuator, in view of constraints (e.g., a deadband range comprising a set point) set on the crossover pressure. Control may be achieved, via a control algorithm (e.g., a Multiple Input Multiple Output (MIMO) control algorithm) acting upon inputs of actuator position feedback and crossover pressure feedback (e.g., as indicated by pressure feedback of each respective pneumatic chamber). Further, the embodiments described herein may reduce the necessary frequency of control actions for adjusting crossover pressure, thus reducing wear on process components, and allowing for finer control of actuator position.

Abstract: A control loop for a double-acting pneumatic actuator is configured to generate two control signals, one for each of the two pneumatic chambers for the purpose of controlling the actuator position in view of operating constraints on the chamber pressures or the stiffness of the actuator. A numerical indicator of the stiffness may be computed in a variety of ways, for example, as the average of the two chamber pressures. In one embodiment a numerical indicator of stiffness is treated as an output of the system along with the position of the actuator. A multi-input multi-output control loop with position and pressure feedback may be used to simultaneously control the position and the stiffness of the actuator.

Abstract: Systems and methods may be provided to digitally control both position and crossover pressure in a double-acting pneumatic actuator, in view of constraints (e.g., a deadband range comprising a set point) set on the crossover pressure. Control may be achieved, via a control algorithm (e.g., a Multiple Input Multiple Output (MIMO) control algorithm) acting upon inputs of actuator position feedback and crossover pressure feedback (e.g., as indicated by pressure feedback of each respective pneumatic chamber). Further, the embodiments described herein may reduce the necessary frequency of control actions for adjusting crossover pressure, thus reducing wear on process components, and allowing for finer control of actuator position.