Proportional control

About: Proportional control is a research topic. Over the lifetime, 3756 publications have been published within this topic receiving 49050 citations.

Closed-loop step response for tuning PID-fractional-order-filter controllers.

Abstract: Analytical methods are usually applied for tuning fractional controllers. The present paper proposes an empirical method for tuning a new type of fractional controller known as PID-Fractional-Order-Filter (FOF-PID). Indeed, the setpoint overshoot method, initially introduced by Shamsuzzoha and Skogestad, has been adapted for tuning FOF-PID controller. Based on simulations for a range of first order with time delay processes, correlations have been derived to obtain PID-FOF controller parameters similar to those obtained by the Internal Model Control (IMC) tuning rule. The setpoint overshoot method requires only one closed-loop step response experiment using a proportional controller (P-controller). To highlight the potential of this method, simulation results have been compared with those obtained with the IMC method as well as other pertinent techniques. Various case studies have also been considered. The comparison has revealed that the proposed tuning method performs as good as the IMC. Moreover, it might offer a number of advantages over the IMC tuning rule. For instance, the parameters of the fractional controller are directly obtained from the setpoint closed-loop response data without the need of any model of the plant to be controlled.

Anti-skid control system employing integral-plus-proportional control of pulsed modulation

Abstract: In an anti-skid type control system for automotive vehicles, apparatus for maintaining wheel slip in a region of values associated with a maximum coefficient of road friction. Periodic modulation of the wheel brake torque in conjunction with wheel acceleration measurement are employed to determine the variation of the coefficient of road friction from an optimum value, while integral-plus-proportional control of the pulse modulation allows compensatory variation of the wheel torque and slip condition to a condition providing the optimum coefficient of road friction.

Replacing a PID controller by a lat-lead compensator for a robot-a frequency-response approach

Abstract: Because of their simplicity, PD (Proportional-derivative) or PID (proportional-integral-derivative) controllers are widely used with various robot control strategies. For dynamic control of robots, this algorithm can be shown to lead to unsatisfactory tradeoffs between static accuracy, system stability, and insensitivity to disturbances. These tradeoffs become more serious as the sampling rate decreases. By deriving a more realistic discrete-time system model and using frequency-response analysis, a lag-lead compensator is designed and implemented. Both theoretical analysis and real tests are given for the comparisons of the PD or PID controller and the lag-lead compensator. Replacing PD or PID controllers by lag-lead compensators results in a small increase of offline design and tuning effort and online computational load, but the improvements in robot performance are significant. >

Optimal and adaptive control of chaotic convection—Theory and experiments

Abstract: In theory and experiments, optimal and adaptive control strategies are employed to suppress chaotic convection in a thermal convection loop. The thermal convection loop is a relatively simple experimental paradigm that exhibits complex dynamic behavior and provides a convenient platform for evaluating and comparing various control strategies. The objective of this study is to evaluate the feasibility of employing optimal control and nonlinear estimator to alter naturally occurring flow patterns and to compare the performance of the optimal controller with that of other controllers such as neural network controllers. It is demonstrated that when the system’s model is not known, experimental data alone can be utilized for the construction of a proportional controller.

Robust model-based control: an experimental case study

Abstract: Three forms of robust model-based control were experimentally evaluated. Algorithm evaluation was prompted by a requirement for controllers with good high-speed tracking accuracy in uncertain payload environments. The test case was a PUMA-560 operating over the standard test suite. The tracking performance of the robust algorithms was compared, with and without payload, to that of a nonadaptive model-based controller with fixed proportional-derivative (PD) feedback. The model-based controllers were made robust by the addition of an auxiliary input term, replacing the PD feedback with a feedback loop based on quantitative feedback theory (QFT), or an adaptive feedforward compensator based on Lyapunov theory. Experimental evaluation provided valuable insight into the potential and limitations of each method. All three techniques improved the tracking performance of the manipulator. Superior overall performance, computational simplicity, and a mathematically rigorous design and tuning procedure make the model-based controller with QFT feedback the algorithm of choice. >