teacher/mentor institute hands-on session: building a robot scott mcewen chuck powell

Teacher/Mentor Institute

Hands-On Session:Building a Robot

Scott McEwenChuck Powell

Overview

Quick and simplified exposure to what your student team will experience.

You will experience some of the same Design choices Building decisions Learning experiences Frustrations

We hope that this will make you a better coach and mentor!

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Caveat Aedificator

This guide has a suggested procedure for building your robot. You may vary from this procedure so long as:

You do not endanger yourself or anyone else. You do not permanently attach anything to

the Returnable Kit parts. You do not damage the room or furniture in

any way. You clean up after yourself.

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Be courteous to our hosts!

Please DO NOT scratch the tables, other furniture or floors, or snag any carpet or furniture fabric.

Keep a box lid or other surface protector between your work and the furniture or floor.

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Charge the Batteries

Before you begin any construction, charge the following:

Both 7.2 V batteries

All 6 AAA batteries

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Install easyC

Install easyC v4 for Cortex (Trial version).

Download from http://www.intelitekdownloads.com/easyCV4/

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Update Firmware

Connect Cortex to computer with USB cable.

Start…easyC… IFI VEXnet Firmware Upgrade.

Click on Search. Click on Bootload. Repeat for Joystick.

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Platform (1)

Construct/Attach: Plywood base Motors SkidMake sure the platform is stable and can roll in various directions.

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Platform (2)

Attach the Cortex.

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Connect Motors to Cortex (1)

Motor Ports 1 & 10 have a built-in. Motor Ports 2-9 require you to connect using a Motor Controller. BEST requires you to use ports 2-9

Motor Ports 1-5 share the same current source, and Ports 6-10 share the same current source. Try to balance motors between 1-5 and 6-10.

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Connect Motors to Cortex (2)

Cortex Motor Port => Motor Controller => Screw Terminal Block => Motor wires with Quick

Connects => Motor Tabs

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Test the Platform (1)

easyC: File … New Competition Project

Field Control Competition Project Operator Control tab. Joystick … Arcade- 2 motor

into while loop. Forward/Reverse Channel: 2 Rotate Channel: 1 Left Motor, Right Motor: (look

where you plugged these in to the Cortex.)

Joystick … JoystickAnalogDeadband => before Arcade.

Deadband for both Channel 1 and Channel 2.

Test-“drive” the platform – make sure the motors respond correctly.

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Wheels

Attach the hubs to the centers of the wheels.

Attach the hubs to the motor shafts.

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Arm

Build and attach the A-frame to hold the arm.

Make and attach an arm that is the right size to: Reach to the ground Be pulled down by

the winch.

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Winch

Build and attach the winch. Mount and attach the

winch motor. Wire the winch motor to

the Cortex. Edit your program to

include the winch motor. Test to make sure it works. Add the spool and string

onto the winch and test again.

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Test Drive

Go to the Build and Download menu. Compile your program. Fix any errors, if necessary.

Connect the USB cable between the computer and the Cortex. Download your program to your Cortex.

Tether the joystick and Cortex – this means connect them with the USB cable.

Turn on the Cortex first, then the joystick. Wait for the ROBOT and JOYSTICK lights to turn green.

Test each wheel motor forward and backward. If either wheel moves in the wrong direction, go back into the program, check or uncheck the box to reverse direction, and try again.

Untether the Joystick and Cortex. Turn them off. Insert the 2 VEXNet keys and turn them back on.

Drive the platform without the tether.

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Servo

Connect the servo to the Cortex with a Servo Controller.

In your program, add a JoystickToServo, and use Channel 5 or 6.

(Servos don’t need a deadzone.)

Turn on the Cortex and Joystick. The Servo will rotate to its “zero” position. Make a note of it.

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Claw

Disconnect the servo from the Cortex.

Assemble the claw, including the servo. Make sure it can move properly.

Remember to assemble it so that its starting position coincides with the servo’s “zero” position.

Reconnect the servo to the Cortex. Turn it on and test the claw.

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Mount the Claw

Attach the claw to the end of the arm.

Make sure it reaches to the ground and can open and close.

You may need to add a servo extension between the servo controller and the servo.

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The Competition

The competition will involve 2 robots at a time, on the same field.

The edges of the field will be marked by a PVC boundary.

Each team will have its own basket.

Balls must go through the ring and land in the bucket.

Blue balls are 1 point each, red balls are 2 points each.

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