How Closed Loop Control of Hydraulics Systems Has Evolved
As the industry has evolved, electrical control has become more prevalent in hydraulic systems. Often in hydraulic applications, there is a need to very precisely control the speed, position, motion profile or to synchronize the motion of multiple actuators. There are now a variety of means to monitor position very precisely in hydraulic cylinders, motors and rotary actuators. Relatively inexpensive PLC or motion control options are used to receive the feedback signals from the actuators and issue command signals to the device used to feed the actuator with flow (speed) and pressure (force or torque).
Usually, a servo or proportionally controlled valve is used to provide the properly controlled flow and pressure to the actuator. There are also a wide variety of options for these which offer a tremendous amount of flexibility when designing a system. It is critical that these be properly sized to ensure proper performance for the application without sacrificing horsepower or performance. There are also some options for proportionally controlling pumps instead of valves. These tend to be a bit less precise but are much more efficient in terms of wasted heat and therefore, horsepower.
Size is no issue! These systems can be as small or large as necessary to do the work. One of the fundamental advantages of hydraulic systems is their power density so taking advantage of this while also very precisely controlling the result is a tremendous advantage.