PID Control

[Mukesh Krish]

hai to all,

                   we are using labview 8.0 to control the MOOG valve (it is used to control the actuator) trougth PID control

                   The oil is pumped by pump motor and the pressure is developed by hydraulic system

PROBLEM

                    when the pressure is switched on the actuator start with a jerk ,resulting in high load in the test equipment, Eventhough we are using pid control, after the initial jerk the system is controling smoothly is there any controler to avoid intial jerk

[Brian_Beal]

I haven't looked at your VI, but it sounds like a classic case of derivative windup.  Is your PID loop running before you turn on the pump?  If it is, then the PID is trying to control, but can't because it isn't seeing a response, and hence keeps increasing the drive signal.  By the time the pump is turned on, the valve is open quite a bit and you get the jerk.

[michenglaoxu]

1: Is load the input of the PID control? so, what's the setpoint (35.4 for what?)

2: What's your control objective?

3: Move your tune on pressure code sequentially with PID control not like parrallel setting  or move it outside of your control loop using state machine.

4: don't initialize the start task and stop task in PID control while loop, move them outside of the while loop.

5: Add at lease 1-50 ms delay in you while loop.

Then, see what happens.