CONDITIONING TECHNIQUE FOR MULTIINPUT MULTIOUTPUT PROCESSES WITH INPUT SATURATION

The problems of controller windup and directional change in controls, in controllers for multiinput multioutput processes with input saturation, is considered. To avoid the windup problem, a generalisation is proposed for the conditioning technique based antiwindup compensator, by introducing a filtered setpoint. This provides a parameterisation to deal with situations where the original conditioning technique was not suitable. To reduce the effect of directional change in controls due to the multiple saturation, further modifications to the conditioning technique are proposed. An interesting outcome is that the generalised antiwindup compensator due to Astrom and Wittenmark is interpreted in terms of the conditioning technique; moreover, these interpretations are used to introduce modifications to their scheme in order to deal with the problem of directional change in controls.