Computer control is concerned with the way computers can be used to control external devices. Instructions can be sent from a computer to a device to tell it what to do and readings from sensors can be sent to the computer to determine what instructions should be sent next.
Outputs include instructions to turn on or off lights, motors, heaters and alarms. Input devices include sensors that can read temperature, pressure, movement and pH.
To begin with we will loo at some examples in the Mission Control program. Inside the program go to Teacher Options and turn off all but the last four exercises. Select Activity Mode and Level 2. Solve the four problems.
To control real traffic lights we have to turn switches for each light on and off for certain lengths of time. Individual traffic lights (such as those for a narrow bridge or road works) are quite easy to construct but there are more complex designs:
As noted earlier, traffic lights are a lot more complicated than you might at first imagine. They are also very important in controlling traffic on the roads, just think what happens when they break down or if they were all set to green.
A motorist waits at a pelican crossing
Left filter light at a pelican crossing
In a Word document (outline in IT folder on K:IT\Third Form) write a sequence of instructions to control the simple traffic lights you might find at a narrow bridge where only one stream of traffic can pass. You will need to define names for six lights, two each of red, amber and green. You may find it best to use a table with two columns to show how the lights are synchronised. Add a title, your name and a short description. Copy and paste some photographs to illustrate your work. Next write down the sequence of lights found at a crossroads. Finally, write down the sequence of lights found at a 'pelican' crossing, showing what happens when the pedestrian button is pressed.
Open Flowol and then choose Mimic/Mimic/Bridge Lights. Create a flowchart in Flowol to implement a full sequence for one set of traffic lights. In the mimic there are two sets of lights for one direction and a single set for the other. The lights on the pair of lights are linked to the same outputs while the lights on the other set are linked to other outputs.
Click on the output numbers at the bottom of the Flowol screen to check which lights are linked to the different outputs. You can then set up a flowchart to move the lights through a complete sequence. Keep the delays fairly short so you don't sit around waiting for the lights to change.
Set up a second sequence of flowchart symbols beside the first one to implement the set of lights on the other side of the bridge. You will need to coordinate the lights carefully so cars do not meet on the bridge.
Use the Lego kit to make some simple traffic lights. Produce a simple program in Robolab and upload it to the RCX to make the traffic lights turn on and off in the correct sequence.
You will need to use Inventor Level 1 for your work.
Use the music capabilities of the RCX brick to create tunes that play back (the sounds could be played when the RCX is doing something else). Note that the main purpose of this exercise is to learn more advanced programming techniques.
You will need to use Inventor Level 2 or 3 for your work.
Create a wall display on the theme of computer control (open-ended exercise, work in groups, design the display and assign different parts of the task to different individuals).