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Navigation Accuracy4 Poles Challenge

Programming the EduBot before trialing on the course

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How far am I going?Work out how far one “rotation” takes the robot.

Place a small mark on the bottom of the wheel.

Go forward one rotation.

Measure this distance

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Checking using Circumference

One rotation is equal to the circumference of the wheel.

To measure the circumference, find the radius.

Circumference = 2 x π x radius

Substitute into the formula:

C = 2 x 3.14 x radius

C = distance of one rotation

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Start

rC 2

Using Distance of a Rotation

How many rotations does it take to get to the corner?You may need to use decimals (eg. 3.5 rotations).

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Now to get around the corner…

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Another CalculationAssuming a pivot turn – one motor only – for

right wheel

Right wheel forward only

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Another CalculationHow many rotations to get to Point A?

AA quarter turn

Right wheel forward only

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Calculate Quarter-turn Distance

Circumference (C = 2πr)

divided by 4

Program in a left turn for your robot.

How many rotations is this for the right motor?

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Good luck with the dotted (outside) line on the 4 Poles Course.

Try and program the EduBot for the whole dotted line course before trialing.

How far around the course did the EduBot go?

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Start

At this point, a wide turn needs to be taken – and the programming gets

interesting!

Now for the Dashed Course…

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28cm

28cm

120cm

120cm

In order to take the wide arch, the two wheels have to travel at a different velocity.

The steering slider in a Move Block is limited to 10 radius of curve turn.

A NEW PROGRAMMING TRICK IS REQUIRED

for more accurate curve turning

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Before the programming tricks…Which set of wheels will create a turning circle with

the biggest radius?

The arrows’ lengths represent power.

A B

Answer

A – the closer the power of the two motors, the wider the turning arc

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Programming a Curved TurnTwo ways

Split task Wait for time

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Split TaskAllows two tasks to operate at the same time.

In this case, two Move blocks representing two separate motors.

Two forms of BranchingClick and drag from the starting point.

Midway in the program – click and drag while the Shift key is pressed.

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Split Task (continued)Things to note:

Motor B and C have different powers.

2 different motors – B and C – both going forward

Duration is time (not rotations) – can you suggest why?

Try both and see.

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Wait for timeTwo separate Move Blocks

(with different motors selected)

Have different powers

Second Curve Turn Technique

and are set to duration unlimited

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Wait for Time (continued)

A “Wait for Time” block is added, and time for the curve turn selected.

You can begin accurate curve turning.

Choose your method.

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Good luck with the dashed (inside) line on the 4 Poles Course!

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