• Introduction
• Requirements
• Application overview
• How to set up
• Bluetooth paring
• Software install
• Connecting the Wii Balance Board
• Connecting to NXT brick
• How to play
• References
• Help and customization or software design support

Introduction

Enjoyable sensory robot game with the LEGO MINDSTORMS alpha rex and the Wii Balance Board. User can control the robot's leg motors speed and direction by changing the vector connecting user's center of balance and center of the board. This simple and sensory robot game is very attractive to elementary school kids so that it is very useful for demonstrations in a robotics summer camp and science museum exhibitions.

Requirements

• Windows machine which :
• .net 3.5 framework http://www.microsoft.com/NET/ ,
• and a Bluetooth radio are installed.
• LEGO MINDSTORMS NXT.
• Wii Balance Board.

Be careful to bluetooth radio compatibility with the Wii Balance Board. In my case, although LEGO NXT control block can be connected to any Bluetooth radio, ThinkPad X61s embedded bluetooth radio can not be connected to the board. Therefore I uses a cheap (less than 20$) USB Bluetooth radio (BT-MicroEDR1X). This application runs evenwhen two bluetooth interfaces are enabled.

Application overview

When application started, a main window shown below with a fixed size of 1024 x 768 appears.

The main window consists of six parts:

1. Laptimer. Timer starts/stops by a "start"/"stop" button placed below.
2. Score board. User can edit this textbox to show ranking, team names or laptime.
3. Hardware connection log. This textblock tells current connection status of the devices.
4. NXT connection dialog. Application try to connect a serial port specified with the textbox when the red-colored "Port" button clicked.
5. Control buttons. Application exits by the "Exit" button.
6. Sensor information display. It shows Wii Balance Board sensor information and NXT robot's motor power.

How to set up

Bluetooth paring

First, devices pairing. The Wii Balance Board pairing starts by pushing a small red button placed near its battery. NXT brick can be connected by making the PC discoverable and start the pairing from the NXT brick. Make sure you record a installed virtual COM port.

Software install

The latest binary file can be get from downloads list. It has no installer. Simply click to execute a binary file.

Connecting the Wii Balance Board

The board is connected to the computer automatically when pushing the small red button near placed the battery. Connection progress is shown in the textblock (2). When connection is established a text message "Balance board is connected" is shown. If the application seems to freeze (it does not respond to mouse click), it may be because a warning dialog is hidden behind the main window. You can show a dialog by pressing "Alt + Tab" and click "OK" button to close it. The connection seems not always to success. If you can not see a text message "Balance board is connected" after one minute, repeat the above procedure for several times.

Connecting to NXT brick

The NXT brick is connected to the computer by clicking "PORT" button after editing correspondent virtual COM port name to the textbox. When connection is established, text message "Connected successfully" is shown.

How to play

The robot walks according to inclination of your body. First, step at the center of the board, and increase forward inclination of your body slowly. The robot starts to walk forward. If you want to step back, bend your body to backward.

References

This application refers following projects:

• AForge.NET Framework http://code.google.com/p/aforge/
• A cross platform C# class library that provides an interface to various Wii related devices. http://code.google.com/p/wiidevicelibrary/

Help and customization or software design support

If you have any questions or need some software customization support, please send a e-mail to facade@reinforce-lab.com. Engineers of our company (Reinforce-lab. http://www.reinforce-lab.com/ ) supports your project.