Activity 5

Plugged into technology

Home

Introduce autonomous mode. (see glossary for info on the word autonomous)

Work out how to get robot to go in curved and straight lines by adjusting the speed difference between the two wheels.

Straight line work can be done on a desk or on a floor area.

10-pin bowling practice requires a large floor area.

Engineering a brighter, younger future

Sponsors

Department of Electrical, Electronic & Computer Engineering
Heriot-Watt University
Edinburgh

This is the first activity where the robot is not directly controlled by the switch controller. The robot will be working in autonomous mode where the computer has to make decisions about what to do. The aim of much of current robot development is to make useful autonomous robots. That is, robots that can be given a task, which they do without a human operator having to direct its every move. An interesting example is the robot vacuum cleaner.
The basis of this activity is that although components are manufactured to be identical, they are never exactly the same. For example, the motors used in the robot are made in the same factory and on the same machines, but are slightly different. The result is that when the two motors are given the same battery voltage, the two motors will run at slightly different speeds. The result is that the robot moves in a curve rather than in a straight line. This is a well known effect. The solution is to get the computer in the robot to make a slight adjustment to one of the motors to get both motor speeds to be as equal as possible.
This idea of using a small computer in a product to compensate for problems in the components is now very common. In fact, every product in a modern household has a computer similar to the one in our robot.

Show activity 5 DVD

Show class the DVD (from main menu select “Activity 5 – Lines and curves”). Approximate running time is 6½ minutes. You can scene select parts of the DVD.
The DVD will explain how to adjust the robot to move in a curved or straight line.

Do activity

Mark out a straight line using tape on the desk or on the floor (lino or tiled only!) Take care if using desks – robots can get damaged if they fall on the floor.
Vary POT-2 positions, observe the effect on the robot and complete worksheet.
Get teams to experiment with changing POT-1 and POT-3 settings.

1.	As this activity can be done in a classroom or in a hall there are different POT-3 settings for working on a desk or on a floor. POT 3 set the time the robot moves forward. On a desk you would want the robot to move a smaller distance than on the floor.
2.	Power on and use robot in mode “A0” (switch sequence A_D_2A)
3.	When the robot display shows “A0” (no flashing) they can press the A, B and C switches. Pressing switch A will cause the robot to perform the move forward. Pressing switch B instructs the robot computer to read and remember the three POT values. (speed, differential (see glossary) and time). Pressing switch C will exit this MODE.
4.	POTs control the following – POT-1 – varies speed POT-2 – adjusts speed of one wheel compared to the other. POT-3 – varies the time the robot moves forward (2 to 8 seconds).

File	Description	Pdf	Word
Activity 1 pupil worksheet	Worksheet to guide pupil though the experiment.