Real-time processing questions and answers
Questions
Q1. Define ‘sensor’.
Q2. Do some research on the Internet. State the names of five sensors and the physical property they measure.
Q3. Define ‘actuator’
Q4. Do some research on the Internet. State the names of two actuators describe an example of its use in each case.
Q5. What is the key characteristic of a real-time system?
Q6. Describe how the temperature in a greenhouse can be controlled using a control system.
Q7. What is meant by the term ‘feedback’?
Q8. Do some research on the Internet. How are robots used in car factories? Watch a video of robots in a car factory.
Q9. What are the advantages of using robots in car factories compared to humans?
Q10. What are the disadvantages of using robots in car factories compared to humans?
Answers
Q1. A sensor is a transducer that responds to a physical property.
Q2. Sensors include Geiger counters, thermistors, speedometer, radar gun, oxygen sensor, proximity sensor and any other suitable sensor (search Google for ‘list of sensors’ to get lots of examples).
Q3. An actuator is a computer-controlled device that causes physical movement.
Q4. Examples of actuators include stepper motors, to accurately control the position of a motor and computer-controlled valves in pipes, to accurately control the flow of a liquid in a pipe.
Q5. In real-time systems, each input must be processed and outputs adjusted before the next input is read and processed.
Q6. In a greenhouse, the target temperature is set. A sensor reads the temperature every 5 minutes and compares it to the target temperature. If it is too hot, then the cooling fan is switched on and the heater is switched off. If it is too cold, then the cooling fan is switch off and the heater is switched on. If the temperature equals the target temperature, then both the cooling fan and heater are switched off.
Q7. Feedback is the term used to describe using data from sensors as input to the program that controls a system. After an action is taken, the sensors read the result of the action and feed the signal back into the system. In this way, a new action can be initiated which brings the system closer to the desired target.
Q8. Robots can be used for many things in car assembly plants. For example, they can be used to move components from one position to another. They can be used to weld components together. They can be used to paint cars.
Q9. Robots work 24/7. They can work to finer tolerances than people. Their performance is always the same as they never get tired or get ‘Friday afternoon’ syndrome. They don’t need breaks. They can work in dangerous places such as the paint area, which is potentially explosive.
Q10. Robots can remove unskilled jobs from car factories leading to potential social problems and an impact on the local economy because there isn’t so much money being spent. Robots are expensive to buy initially, although over time they should save money. Robots are only as good as the programmers who write their programs. They can’t deal with new situations or use intuition if something unexpected happens.