TABLE OF CONTENTS Computers can also be used in control applications.
Microcomputers are able to handle inputs and outputs that are either digital or converted analog signals. With the proper software, they are capable of making decisions about those signals and can react to them quickly and precisely. These features make microcomputers ideal for controlling other digital or analog systems, as discussed in the following sections.
Recall the basic closed-loop control system block diagram of Chapter 2. The error amplifier compares the command input with the plant output and sends the error signal to the control logic. The control logic uses the error signal to generate a plant control signal that causes the plant to react with a new output so that the error signal will be reduced toward zero. The control logic is designed so that the plant s output follows or tracks the command input. A microcomputer can replace the error amplifier and the control logic. The computer can compare command input and plant output and perform the computation required to generate a control signal.
The limit-cycle controller, discussed in Chapter 2, can be readily implemented with a microcomputer. Recall that the limit-cycle controller controls the plant output so that it falls somewhere between an upper and lower limit, preferably so that its average value is equal to the command input. The controller must read in the command input and the plant output and decide what control signal to send...
