Event based control applied to wireless throttling valves

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.