TURNING
How can your robot turn when it doesn't have a steering wheel?
The picture shows a robot moving in a circle. It shows 2 wheels which we can call the inside wheel and the outside wheel.
The inside wheel makes the small circle and the outside wheel makes the big circle as the robot goes around.
The picture shows a robot moving in a circle. It shows 2 wheels which we can call the inside wheel and the outside wheel.
The inside wheel makes the small circle and the outside wheel makes the big circle as the robot goes around.
Which wheel moves the furthest?
Which wheel turns the fastest?
Which wheel turns the fastest?
MOVE TANK TURN
Delete all blocks in your program. Drag one Move Tank block to the Start position.
Change 1 of the motor's power settings, leaving the other at 75. You can type or use the slider. Make sure the turn is for 1 Rotation. Download and run.
Typing the Power is often easier than using the slider if you have an exact number in mind.
Put a marker on the side of each wheel. Watch each wheel in turn as the program runs. Do they both make one whole rotation?
If not, describe what happens.
Change the Rotations: setting to 10 rotations. Download and run. Can you see the circle the robot is trying to travel around?
Now change the power setting to -75. Download and run.
If not, describe what happens.
Change the Rotations: setting to 10 rotations. Download and run. Can you see the circle the robot is trying to travel around?
Now change the power setting to -75. Download and run.
Mark with a pencil a place on the side of each wheel hub. Watch each wheel in turn as the program runs. Do they both make one whole rotation?
Have you noticed that one wheel is now turning the other way?
Where is the centre of the turning circle now?
Choose a start position for your robot that you can remember, and run your program. Estimate (or measure) how many degrees your robot turns.
Now change the power setting to 10 and -10. Download and Run using the same starting position as before. Does your robot turn the same distance as before?
Have you noticed that one wheel is now turning the other way?
Where is the centre of the turning circle now?
Choose a start position for your robot that you can remember, and run your program. Estimate (or measure) how many degrees your robot turns.
Now change the power setting to 10 and -10. Download and Run using the same starting position as before. Does your robot turn the same distance as before?
ONE WHEEL TURN
Delete all your blocks. Drag a Large Motor block to your program. Set it to On for Degrees.
This number will be very useful for the Little Red Riding Robot Challenge, and other challenges ahead.
Change the motor selected to motor C to make the robot turn the other way. Test your program.
Change the motor selected to motor C to make the robot turn the other way. Test your program.
MOVE STEERING TURNS
There is another Move block for moving both wheels together. The Move Steering block. This block just has one setting for power. It has a slider for choosing the angle of the turn. The slider range is from -100 to 100. A setting of 0 should theoretically make the robot travel straight ahead, but in reality the Move Tank block is better for this.
Delete all blocks in your program and drag one Move Steering block to the start position.
Experiment with the slider settings. Notice which way the wheels are turning. Make sure you can program a wide turn as well as a tight one using this block.
Delete all blocks in your program and drag one Move Steering block to the start position.
Experiment with the slider settings. Notice which way the wheels are turning. Make sure you can program a wide turn as well as a tight one using this block.
Make your robot perform a Steering = 100 turn for 1 rotation. Lower the power if you like. Change the Rotations setting to Degrees. Download and run.
TURN SUMMARY
These are the three different types of turn your robot can make, but there are different ways of making them happen.