NXT Forklift

Fun Projects for your LEGO^® MINDSTORMS^® NXT!

Forklift

Building:
Program:

Building Instructions

1-14

Start by building the 3-Motor Chassis. Click the picture for building instructions.

Note: You will need to rotate the bushed pegs on the chassis to fit the axles on the sensor attachment.

Plug the ultrasonic sensor wire into port 4 on the NXT.

Use about 24 inches (61 cm) of kite string or other thin string.

Tie one end of the string to the axle of the winder and the other end to the center hole of the beam,
as shown below.

To attach the lift assembly:

Route the string up and over the top bar as shown above.
Insert the lift assembly from the bottom of the forklift and inside the rails as shown below.
Attach the 9-beam to the top of the lift.
Take up the slack in the string by winding the gear on the motor so that the string comes out in front of the winder as shown below.

Route the wire under the NXT as shown below to keep it out of the way, then connect it to port 3.

Forklift Programming

The ForkliftTest program is an example of an autonomous (not remote-controlled) task for the forklift, using a combination of rotation sensors and the ultrasonic sensor. See the instructions below to set up this task.

The Forklift can also be operated by Bluetooth remote control from your PC. The standard remote control feature included in the NXT 2.0 software is a little too limited to easily control the forklift, but the following alternative is available. If you have a working Bluetooth connection between a Microsoft Windows-based computer and your NXT (you can download programs to the NXT by Bluetooth instead of using the USB cable), then you can use this Bluetooth Vehicle Remote program written by Anders Søborg to control the Forklift using the keyboard or mouse on your computer. See the instructions below to set it up.

If you have two NXTs, see the Dial Remote Control project to control the Forklift from an NXT-based wireless (Bluetooth) remote control.

How to Set up for the "Forklift Test" program

The ForkliftTest program is an autonomous NXT program that can be used without Bluetooth remote control. It will make the forklift lift the load of tires and place it on top of a platform by itself. The starting position for this task is as shown below.

Platform height: 5.5 - 6 inches (14 - 15 cm)
Distance from Forklift to load of tires: about 3 inches (7 cm)
The distance from the load to the platform doesn't matter because the program will use the Ultrasonic sensor to find the platform.
Use the gears on the lift winder to manually lower the lift until it just barely touches the ground.
It helps if you straighten the castor wheel behind the robot first, so that the Forklift will start straight.

How to Use the PC Bluetooth Vehicle Remote with the Forklift

You need a Microsoft Windows based computer to run this enhanced Bluetooth Vehicle Remote program. The standard remote control included in the NXT 2.0 software will also work (on Windows or Macintosh), but is much less convenient to control the lift with because you can't easily reverse the lift direction.
You need a working Bluetooth connection between your computer and your NXT. Your connection works if you can download programs from your computer to your NXT by Bluetooth instead of a USB cable. If you have never tried this before, see your Mindstorms User Guide for instructions. Bluetooth can be tricky to get set up, and some computers are not capable of doing it. Sorry, I cannot help you with this part.
If you have more than one NXT, make sure that the one you are using for the Forklift was the last one to connect the LEGO Mindstorms software by Bluetooth. You can do this by downloading a program (any program) to your NXT by Bluetooth.
Exit the LEGO Mindstorms software. The Bluetooth Vehicle Remote will not be able to connect to the NXT if the LEGO Mindstorms software is still connected to it.

Find out what "Comport" is being used for your PC to NXT link. You can do this by going to the Control Panel on your computer, running the Bluetooth control panel application, and looking for information on the connection there. For example, the Bluetooth Control Panel on my computer, shown in the picture to the right, shows under the COM Ports tab that my NXT device named "Dave" is using Comport 6 ("COM6").

Turn your NXT on. You don't need any program running on the NXT for the remote control to work.
Run the Bluetooth Vehicle Remote program (nxt-remote.exe) available here. This program runs on your PC, not on the NXT.
Set the Comport dropdown to the port determined in step 5 above.
Set the controls as shown in the picture to the right as a starting point:
- Motor 1 = Motor B, Float
- Motor 2 = Motor C, Float
- Speed = 50
- Spin Speed = 25
- Turn Ratio = 25
- Motor 3 = Motor A, no Float
- Motor 3 Speed = 75
Press the Connect button to establish a Bluetooth connection to your NXT. If this works, it will display "Connected".
Use the Drive buttons or Keyboard controls to control the Forklift.
Experiment with different speeds and settings to see what you like best.

Challenges

Try modifying the ForkliftTest program do to some different tasks.
Practice driving the Forklift with the Bluetooth remote control. Can you stack things up on a shelf with 3 different levels and take them back down again?
If you have some other LEGOs, try making some blocks and other parts that can be lifted by the Forklift. Can you build a tower of parts that stack on top of each other, and whenever you lift one it lifts all of the ones on top of it too?
This Forklift design uses most of the beams and pegs in the NXT kit, but if you have some extra parts, can you make it lift even higher?
If you lift heavy items up high, the Forklift may fall over. What could you do to prevent this? What do real forklifts do?

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