Types of Automated Control

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Robotics Task 8

Create a page called Robotics Task 8 and answer the following questions.

  1. Explain the purpose of a sensor. Explain the difference between active and passive sensors.
  2. Explain the function of an induction loop in a traffic light system.

  3. How are alarms activated in home security systems that contain light sensors?

  4. Toll roads with electronic payment sensors can be found in several Australian cities. Explain the purpose of a toll road system and draw a diagram to represent the system, showing its main components.

  5. Countdown timers are being trialled on pedestrian traffic lights in some parts of New South Wales. Explain how these systems operate and discuss whether or not you believe they will improve pedestrian safety.

Note: This task is due on Week 7

Active and Passive Sensors

Active sensors require physical interaction between the sensor and another device. These sensors use sound waves rather than light or visual data. For example, active sensors may be used to track people in a building or they may be used to trace the location of ships at sea.

Passive sensors require a change in the environment in order to operate. For example, most security systems use sensors called passive infrared detectors (PIR) to detect intruders and turn on an alarm. PIRs are electronic devices that detect body heat when intruders enter or move around a protected area.

Traffic Lights

Traffic lights use a range of sensors to control traffic and help keep people safe on the roads. Commonly, traffic light systems use an inductance loop placed in the road. As a car goes over the loop, a small current is induced. This is fed to the processor controlling the system. The system then recognizes that a car is present.

Some traffic lights do not use sensors. At busy intersections, for example, traffic lights may simply operate on timers in order to ensure that traffic moves as smoothly and safely as possible

traffic light system

Security Alarms

Alarms are used in homes and commercial buildings. A common design is an alarm which uses a motion sensor detector to pick up unexpected movements in its path. These types of systems have two main components:

  • a source of light such as a laser beam
  • an optical/light sensor.

In a home security system, the light beam is aimed at the light sensor, across a passageway. When somebody walks between the light source and the sensor, the path of the beam is momentarily blocked.

The sensor registers a drop in light levels and sends a signal to the control box. This activates a timer and allows the homeowner to enter a security code. If the light source is disturbed by an intruder and the security code is not entered, then the alarm sounds.


Motion Detector

Sensing Devices

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Household Control

Computer control systems are a common feature in many households already.  These include automated:

  • security systems
  • climate control systems
  • sprinkler systems
  • audio/visual sound systems.

Automated Security Locks

Car Navigation System

Satellite navigation systems (sat navs) provide drivers with directions as well as traffic and estimated time of arrival information.

Sat navs use global positioning to help drivers determine where they are at any one time.

Automatic Door

Automatic doors use a sensor to open doors at the required time. The sensor is often placed at the head of the door. It is passive and may be an ultrasonic device or a passive infrared detector. When the presence of a person is detected a message is sent to the controller to open the door.


The development of nano-enabled sensors is in the early stages but the technology is expected be a strong force in the treatment of a range of illnesses from the common cold to cancer.

The present era of nanotechnology has reached to a stage where scientists are able to develop tiny programmable machines which can work inside a patient’s body.

Nanotechnology may enable engineers to construct sophisticated nanorobots that can navigate the human body, transport important molecules, manipulate microscopic objects and communicate with physicians by way of miniature sensors, motors, manipulators, power generators andmolecular-scale computers.