Charles L. Phillips

Analytical Bode Design of Controllers

This paper extends an approach for the analytical design of controllers by frequency-response techniques to include the dc gain as a design parameter. Additionally, the technique is extended to the design of proportional-integral (PI) and proportional-derivative (PD) controllers, and a more direct proof of the design technique is given.

Robust Design of a Digital PID Predictor Controller

A digital proportional integral-derivative (PID) predictor controller is analyzed, and its advantages relative to the normal PID controller are derived. A design procedure which results in a robust control system is developed. This procedure applies to both the PID predictor and the normal PID controllers. A regulator carbon dioxide control system which requires disturbance rejection is designed as an example.

New Centroid Algorithm Based upon Amplitude-Angle Signature

A method of estimating the centroid location of a target utilizing radar scan return amplitude versus angle information is presented. The method is compared with three thresholding estimators and a first moment estimator in a computer-simulated automatic landing system. This new method is the most robust and accurate during periods of low signal-to-noise ratio. In periods of high signal-to-noise ratio the method has less error than the thresholding methods and is similar in accuracy to the first moment estimator. Furthermore, the number of pulse transmissions required to obtain a desired level of performance in noise is much less than that needed for the thresholding methods and the first moment estimator employed in this simulation.

Using simulation to calculate floating-point quantization errors

This paper considers digital controllers using floating-point arithmetic. An error analysis tech nique is developed and is implemented by a computer program that is based on a simulation of the system. The outputs of the program include the form required to minimize quantization errors and the output errors for a given bit configuration. The program can be integrated into system simulations.

The X-transform and its use in sampled data system analysis

Abstract This paper discusses the development of a new transform, called the x-transform, for a sampler-hold combination in open-loop and closed-loop sampled-data systems. The x-transform is a special form of the Laplace transform and is applicable to sampled-data systems which have all samplers followed by zero-order hold devices. The x-transform inherently eliminates a spectral requirement of the z-transform which is that all samplers must be followed by a hold device in order to be assured of accurate results. The x-transform is developed utilizing the change of variable, χn = e−nTs/s where T is the sampling period in seconds, s is the Laplace transform variable and n = 0,l,2, ⋯. The x-transform is defined as e(t) = E(s)/ (ϵ-nTs/s) = xn. It is noted that the definition of x differs from that of z by a sign change in the exponential and an s in the denominator.

Design And Implementation Of An Environmental Chamber Digital Control System

This paper presents t he design and implementation (using a TI 9900 microcomputer system) of digital control systems for an environmental chamber utilized in the study of plant growth. Two control systems were implemented - one to control dry-bulb temperature and the o ther to control the carbon dioxide content in the chamber atmosphere. In addition, real-time data acquisition, automatic restart following power outages, and an interactive operating system have been achieved. The CO system is a closed-loop modified proportional control system. The closed-loop temperature control system uti1 ized a proportional-plusintegral-plus-de rivative digital controller. The environmental chamber is presently used in research by the USDA at Auburn University. 2

An Evaluation of Department Head Performance

This paper describes the performance evaluation of the Department Head used by the senior Electrical Engineering Faculty at Auburn University during the last two years.

An approximation for the damping ratio zeta in a second-order system

The authors present a relationship for estimating the value of the damping ratio zeta of a second-order control system from the systems step response. This relationship gives more physical meaning to the damping ratio, such that students have better insight into its significance. >