Modeling of separate meter in and Separate Meter out control system

The schematic of Separate Meter In and Separate Meter Out (SMISMO) Control system is introduced first, nonlinear simulation model is built for SMISMO Control system, parameters of simulation model are verified by experiment. The flow rate through the SMISMO valve at low pressure differential is not tested in detail before, through introducing extra variable area orifices to fit the measured valve flow rate and pressure differential data, the flow rate through SMISMO control valve at low pressure differential can be estimated more accurately. The cylinder friction indirectly measured by experiment is used to improve the friction model parameters. Comparison of simulation model with real system has been carried out in open loop test. The verified simulation model have captured the essential characteristics of real system, the whole model is used for testing the proposed controller of SMISMO control system, simulation shows the speed of piston in the cylinder and rod side pressure of the cylinder can be both controlled to achieve velocity control and energy saving characteristic of SMISMO control system. Its another way to realize cylinder speed control of SMISMO control system without using piston velocity transducer.