Measurement and Control

1
Measurement and Control

• Letts Chapter 16

2
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.

3

• 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.

4
A Simple Control System
5
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.

6
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.

7
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

8
Feedback

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

9
Process Control

• Process control means automatic control of an
  industrial process

10
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.

11
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 .