Using a PID loop to for motion control of three hydraulic cylinders?

[gvanderloop]

I am designing a motion control loop using the DL405. In my application, I have three Temposonice MPS Position transducers attached to three hydraulic cylinders. The MPS transducers are sampled using a F4-04AD module and the in and out motion of the hydraulic cylinders are control using F4-04DA2 which in turn controls the hydraulic valve driver (this generates the PWM current pulses to valve).
My application is to drive these hydraulic cylinders at a selected RPM (1-20) and the cycle of each cylinder is shifted 120 degree. So, cylinder 1 phase = 0, cylinder 2 phase = 120 and cylinder 3 = 240 when referenced to cylinder 1. I can calculate the positions of each cylinder at known time intervals. So, I know where each cylinder should be at a particular time. My questions are:
1.   Would the PID Algorithm work for this type of application?
2.   Can I use look-up table to update the SP of the PID loop?
3.   Can I set up the sample time of the PID loop to some fixed time interval?
4.   Can I insure that all three transducers are sampled at the same time?
5.   How can I insure that the PID loop is not active when the new SP is being written?
Appreciate any comments, opinions or criticisms.

[bfloyd806]

I'm doing the samething in a way here. I have around 20 machines 3 axis each which I use MTS sensors on each one attached to 8" long 4" bore cylinders. One axis clamps the part down while the other two perform the work all. I can keep a tolerance of 0.002" using prop valves and have a cycle time of less them 20 seconds to split a steel disc in half and form a pulley. I have found for safety reasons to use Delta Computer Systems RMC101 controller. I program all my different jobs in to the Vmemory locations on the plc via a C-More. When the operator calls a job up the positions are downloaded in to the motion controller and it waits for the start signal from the plc. An operator is reaching in and out of the machine every 20 seconds, they are very safe and really easy to program.