Proportional control

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

A novel PID controller for pneumatic proportional valves with hysteresis

Abstract: A novel modified PID (MPID) controller is developed to control and minimize the effect of hysteresis in pneumatic proportional valves. It consists of four parts: a proportional-integral-derivative (PID) controller, feedforward term, an anti-windup mechanism, and bang-bang controller. The result is a unique modified PID (MPID) control scheme that demonstrates better command following and disturbance rejection qualities than conventional PID (PID+feedforward+anti-windup) scheme. The control scheme is simulated based on an empirical model derived from actual valve measurement data. The results show that the proposed MPID controller provides better step response, command following, and greater bandwidth than conventional methods. Furthermore, it is demonstrated that the robust control is achieved in the presence of significant dynamic variations in the valve. In particular, it is shown that satisfactory performance can be maintained when the valve hysteresis characteristics are varied by as much as 30%.

Adaptive variable bias magnetic bearing control

Abstract: Most magnetic bearing control schemes use a bias current with a superimposed control current to linearize the relationship between the control current and the force it delivers. With the existence of the bias current, even in no load conditions, there is always some power consumption. In aerospace applications, power consumption becomes an important concern. In response to this concern, an alternative magnetic bearing control method, called adaptive variable bias control (AVBC), has been developed and its performance examined. The AVBC operates primarily as a proportional-derivative controller with a relatively slow, bias current dependent time-varying gain. The AVBC is shown to reduce electrical power loss, be nominally stable, and provide control performance similar to conventional bias control. Analytical computer simulation and experimental results are presented.

Practical industrial control techniques

Abstract: This paper describes several practical control techniques which are most suitable for industrial control. The discussion is limited to the control of time-invariant linear deterministic systems. Both frequency-domain techniques and time-domain techniques are considered. Among them are PID control, lag/dead control, linear-quadratic control, dynamic matrix control, internal model control, disturbance observation control, variable structure control, fuzzy logic and/or neural network aided control. The basic concept of each technique is reviewed and its merits and drawbacks discussed. >

Increasing the Accuracy of Digital Force Control Process Using the Act-and-Wait Concept

Abstract: Proportional gains are to be increased in force control processes in order to reduce the force error. However, the control process may become unstable for large gains due to the digital and delay effects. In this paper, the act-and-wait control concept is compared with the traditional, continuous control concept for a digital force control model with proportional feedback subject to a short, one sample unit feedback delay. Both concepts are implemented in an experimental setup. It is shown that the proportional gain can be increased significantly without losing stability when the act-and-wait controller is used; thus, the force error can effectively be decreased this way. The results are confirmed by experiments.

Integration proportional controller in servo-control system

Abstract: An integration-proportional controller in a servo-control system comprises in one aspect, an integrator for integrating a deviation of an input speed reference signal from a feedback signal fed back from an object to be controlled, and a proportional amplifier connected with the integrator for amplifying the feedback signal, the integrator including a clamping function in which an output value therefrom and an initial value for the next successive integration are changed, when the output value as a result of integration of the deviation is out of a predetermined proper output region, to the nearest boundary of the predetermined region value. In another aspaect, a saturable integrator is provided for integrating a deviation of an input speed reference signal from a feedback signal fed back from an object to be controlled, a proportional amplifier is connected with the saturable integrator for amplifying the feedback signal, and a deviation clamping device is connected with the saturable integrator for limiting the upper and lower values of the deviation.