• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.4
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• pp.112-122
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• 1999

In realistic control systems the nonlinear saturation attributes of the control actuator due to physical limitations should be taken into account This nonlinear saturation of actuators may cause not only deterioration of the control performance but also a large overshoot during start-up and shut-down. As the overshoot increases the system may become oscillatory unstable. in this paper the supervisor implementation which guarantees good performance for saturation operation and prevents reset wind up is presented, Moreover the sufficient conditions of the stability for saturated system using supervisory control with a dynamic controller are provided in the continuous-time and in the discrete-time domain Numerical example is illustrated to depict the efficiency of supervisory control for a typical satuaurated production-distribution system controlled by a discrete-time dynamic controller and to validate basic results by simulation.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.3
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• pp.156-165
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• 1997

In the practical control systems, the dynamic range of actuatiors is limited(or saturated) when actuators are driven by sufficiently large signals. This gives rise to a nonlinearity as a result of actuator saturation. For example, the upper limit is imposed on productive capability by available factory space and capital equipment. Other examples of those kinds of actuator saturations are a maximum torque of the actua- ting motors and a throttle position in an aircraft speed control A saturating actuator may lead not only to a large overshoot during start-up and shut-down, but also to deterioration of the performance due to the uncertainties. That is, the speed of response is decreased and, possibly, the system output may not follow the lalrge reference inputs. The large-overshoot may be accompanied by rest wind-up(or called by integra- tor wind-up) which comes from controllers with integral action in saturation operation regions. Eventually, as the overshoot increases, the system has a limit cycle or becomes oscillatorily unstable. Due to these cir- cumstances, many studies are focused on the stability and robustness of the nonlinear systems with satu- rating actuator in the time-domain as well as in the frequency-domain.