Peter Nachtwey
Member
Yes, I know that proportional only control is simple and will work for simple applications but there comes a point where the performance is not good enough. It is worth while to put the extra effort in the hydraulic controls when controlling an expensive machine where though put is vital. This is the case in the forest products industry of which I am vey familiar.
I have a hydraulic simulator written in Python here:
https://deltamotion.com/peter/py/HydSim.zip
It allows you to chose the target generator.
open loop gain
natural frequency
damping factor
closed loop control
feed forwards.
This program is what I use to generate the graphs for my Hydraulics and Pneumatics magazine articles.
This allows me to show or compare different algorithms and how they will do with different types of hydraulic designs.
Proportional control really does suffer from a slow response compared to PD control. I didn't mention PD control above. PD control also offers 4 times the bandwidth over proportional only control. There is no integrator so there is no integrator wind up and overshoot.
What PLC people do not realize is that the hydraulic/mechanical design determines the performance of the system. You can change the gains and make the response worse but the optimal gains cannot improve the performance of the system beyond the limits set by the hydraulic and mechanical design. This has been true until we figured out new algorithms for control. If has only been in the last 15 years with our advanced algorithms that these limits can be exceeded.
BTW, the RMC150E would interface to a CompactLogix using Ethernet/I{ easily. In sawmills, the most common means of control is a Rockwell Control Logix and Delta RMCs.
I have a hydraulic simulator written in Python here:
https://deltamotion.com/peter/py/HydSim.zip
It allows you to chose the target generator.
open loop gain
natural frequency
damping factor
closed loop control
feed forwards.
This program is what I use to generate the graphs for my Hydraulics and Pneumatics magazine articles.
This allows me to show or compare different algorithms and how they will do with different types of hydraulic designs.
Proportional control really does suffer from a slow response compared to PD control. I didn't mention PD control above. PD control also offers 4 times the bandwidth over proportional only control. There is no integrator so there is no integrator wind up and overshoot.
What PLC people do not realize is that the hydraulic/mechanical design determines the performance of the system. You can change the gains and make the response worse but the optimal gains cannot improve the performance of the system beyond the limits set by the hydraulic and mechanical design. This has been true until we figured out new algorithms for control. If has only been in the last 15 years with our advanced algorithms that these limits can be exceeded.
BTW, the RMC150E would interface to a CompactLogix using Ethernet/I{ easily. In sawmills, the most common means of control is a Rockwell Control Logix and Delta RMCs.
