Hydraulic actuator moving a load

The goal of this section is to illustrate how it is possible now in Simcenter Amesim to integrate green design aspects in a subsystem performance optimization procedure, thanks to the power and energy variables. Let us consider here an example of hydraulic actuator that moves a load (20 kg) and on which control is applied using a position feedback. One can easily imagine that the underlying principle of this simple use-case moving a load in a position control loop , is something that is very common, even if the involved control strategies are more complex in real-world situations.

Figure 32: hydraulic actuator with position control loop

In this study, a duty cycle position (0.1m) is specified and compared to the signal given by the position transducer used to measure the actuator displacement. The difference between the duty cycle position and the position indicated by the transducer is the error used for the control. This error is subject to a gain, k, and the resulting signal is transferred to the servo-valve.

The goal of this study is to optimize the value of k, such that the duty cycle position is reached as fast as possible and with limited oscillations.

The figure below shows the cylinder displacement obtained for different values of k, which illustrates the fact that the value of k has a direct influence on the performance.

Figure 33: cylinder displacement [m] for various values of the control gain

As we can imagine, higher values of k lead to faster responses but these are subject to oscillations, while small values lead to a more stable behavior but with longer response times.