Measurement and Control

Control Systems A control system usually consists of a processor, a control program, interfaces and a device under the processor's control. The processor sends control signals through an output port which allows for: -different types of signal; -different types of cable connection.

To carry out tasks, the controlled device contains any of: -a relay, which is a switch operated by an electrical signal; -an actuator, which is a device to produce movement when given an electrical signal; -motors to produce large-scale movements.

A Simple Control System Computer Output Port Joining Cable Control Signal Actuator

Stepper Motor A stepper motor is a type of motor which needs to be sent repeated pulses to keep it going. A stepper motor has the advantage of precise control.

Interfaces An interface is used to connect two devices or systems to enable them to communicate. Control systems often need to include: -analogue-to-digital (A-D), or -digital-to-analogue (D-A) converters.

Sensors A sensor is a monitoring device which sends signals back to the processor via an input port. There are many types of sensor: -a thermocouple for measuring temperature; -a pressure pad -an infra-red sensor -an analogue light sensor

Feedback Feedback means using output from a system to affect the input.

Process Control zProcess control means automatic control of an industrial process

Robots A robot is a device programmed to do work otherwise done by people. An android is a robot which looks like a human being. Robots which move may use wheels, caterpillar tracks or legs. Sensors installed in a robot allow feedback and improve safety.

Datalogging Data logging is automatic recording of data as it is produced. Data acquisition is capture and storage of data for data logging. Data logging systems may display results continually and/or analyse them later.