Assessment of controller output saturation in dynamic systems: a case of performance, efficiency and system stress trade-off

This paper aims to assess the impact of incorporating limitations into the controller output. The study is conducted on a proportional-derivative controller (PD) applied in the stabilisation of an inverted pendulum system. The findings indicate the presence of a trade-off relationship between the limit imposed, the power of the control output, actuator stress and system performance. It's discussed how the power of the control actions changes with the limitation, presenting a threshold for stability. A relation between limit percentage and oscillation amplitude is also discussed. The findings may help to better understand the trade-off relation between actuator stresses, stability and power consumption, given it's direct relation to the controller output. It can also aid in to assess the implications of saturation on real world systems. As a secondary effect, the limitation proposed can also be presented as a simple method to change the system behaviour with only one parameter change, without changing the gains of the controller.