Showing papers on "PID controller published in 1973"

Pid controller for heating, ventilating and air conditioning systems

Abstract: A heating and/or air conditioning system including a novel controller of the PID type. A proportional integrator (PI) circuit is arranged to receive the output signal from a differentiator (D) circuit which has been delayed and inverted in a summing circuit together with an input control signal to thereby provide a PID controller having a negative delayed D influence. Such controllers are sometimes referred to as a PIminus-D controller. The circuit employs operational amplifiers and the time delay provided by the differentiator circuit is 7 minutes as compared with the time constant of approximately 2 minutes for the integrator and the PI portion of the circuit. The PID controller as disclosed operates through a broad range of frequencies between about 20 seconds and 50 minutes to produce a substantially optimum regulation of the fuel or heat exchanging medium control valve without the need for a separate field adjustment by the installation mechanic.

A new method of optimal digital PID feedback control

Abstract: This paper presents a now method of optimal digital PID feedback control for a linear multivariate system by using a, parameter optimization technique. The most difficult points for the design of optimal digital PID feedback control system by the modern control theory are : (1) the control structure of it is specified in advance, (2) unless all the state variables are fed back, the optimal control cannot be obtained by dynamic programming or the maximum principle. However, the optimal digital PID feedback gains are determined by using the parameter optimization technique in this paper. When there are some states which are not fed back in the control system, the optimal feedback gains depend on the initial states. First, the optimal solution is presented in the case where all the initial Btates are known. Next, it is extended to the case where the initial states are random variables and their statistical properties are known,

Moving-cell vehicle control over nonlevel terrain

Abstract: The application of a proportional-integral-differential (PID) control scheme to the problem of regulating the longitudinal motion of vehicles traversing nonlevel terrain is presented. A third-order representation of the vehicle dynamics is used, and a moving-cell (fixed reference) controller is designed using pole placement techniques. Analog computer simulation results are presented.

Design and Application of a Time-Optimum Controller for a Class of Nonlinear Processes

Abstract: A procedure was developed to extend time-optimum control of linear processes to a class of nonlinear processes consisting of a second-order overdamped linear process followed by a nomemory nonlinearity. Bang-bang control was combined with a proportional-integral-derivation (PID) controller to achieve time-optimum control for set-point changes and good regulator operation for minor disturbances. This dual-mode controller was implemented with a small digital computer. The settling time for step set-point changes with dual-mode control was compared to that with PID control alone. A factor of 2 improvement was achieved through time-optimum control. The dualmode control was successfully applied to an actual nonlinear process.