Control of unstable delayed systems with input saturations and measurement constraints: An electrical cart application

This paper deals with the position control of a mobile vehicle. The main constraints refer to the lack of measurements, presence of input/output delays and actuator saturations. Position measurement of this vehicle is given by a vision system, whose frequency is limited due to picture computation, whereas the control action can be applied at a faster rate. Not only the measurement rate is low, also a conversion delay must be considered. Additional delays can also appear in the control action updating, where actuator saturations should be considered. This paper demonstrates that the use of a prediction-observer scheme, based on a linear model of the system and executed at a high rate, can stabilize the system. This is done even if the control law is non linear, due to the appearance of saturations, also coping with the input/output delays.