Event based control applied to wireless throttling valves
Terry Blevins, Mark S. Nixon, Willy K. Wojsznis · 2015
This paper addresses the PID modifications and communication support that enable effective control using wireless throttling valves. To conserve the battery power used by a wireless positioner, the PID in a control system can be modified to minimize changes to the actuator position.. Effectively, a controller's output to an actuator is event-driven. It is not based on regular scan periods. A new WirelessHART command is proposed that allows the PID to compensate for communications delays from the control system to wireless throttling valve. This paper presents the performance achieved in a flow lab using an industrial size prototype wireless throttling valve in closed loop control of a liquid flow process. In this wireless control field trial, control performance using a wireless valve was evaluated using both a wired and wireless transmitter for the flow measurement.