Physics with a WiiMote
I recently discovered that you could communicate with Wii controllers such as the WiiMote and Balance Board using a PC. This set me thinking about using them to demonstrate some Physics principles. As a result, I have developed a piece of software that is capable of retrieving the data from a Wii controller in real time. The software is pretty basic but it has most of the features that I want built into it, I will gradually add more to it as I think of more ideas or receive suggestions from others that have used it.
This site is intended for anyone who is interested in using their WiiMote for Physics demonstrations. There are some basic guides to get your PC and WiiMote communicating, using my software, and a few ideas to get you started with WiiMote Physics.
I recently presented much of the material described on this website at the IoP East Midlands Physics Teacher Network Day in Leicester and the presentation and associated file can be downloaded by clicking on this link.
The WiiMote - Technical Background
The WiiMote is Nintedo's game controller for their Wii gaming console. It allows the user to interact with the game by using gesture recognition and pointing. In order to achive this, the WiiMote has two key features built into it, an infrared (IR) camera and a three axis accelerometer. The technical details of these two components can be found on many other sites (for example, http://wiibrew.org/wiki/Wiimote/). I will briefly describe the details appropriate to WiiMote Physics.
Infrared (IR) camera
The camera is situated at the front of the WiiMote behind a red plastic filter. The camera is capable of tracking up to four IR sources on its 1024 x 768 pixel display. If only two sources are used (as in the Wii Sensor Bar), it is possible to calculate the distance between WiiMote and the sources by triangulation (see below).
The sensor bar is rather inappropriately named since it does not actually sense anything at all. Instead the sensor bar has two clusters of 5 IR LEDs positioned about 20 cm apart from one another. The purpose of these LEDs is to provide a light source for the IR camera to track in order to determine the position of the WiiMote in space. It is possible to make your own sensor bar using LEDs purchased from Maplin (see photo below).
The accelerometer is situated on the circuit board of the WiiMote. The accelerometer can measure the acceleration experienced by the WiiMote in three spatial dimensions (X, Y, and Z). It can measure accelerations in the range ± 3g with 8-bit resolution which means that the smallest change in accelertion that can be detected is 0.0234g.
Using the WiiMote to Explore Physics
Using both the accelerometer and camera I have succesfully incorporated WiiMotes into the following Physics demonstrations:
- Simple Harmonic Motion on a Spring (simultaneously tracking the acceleration and displacement)
- Pendulum motion (small amplitude motion by tracking the postion of an IR source and large amplitude motion using the accelerometer)
- Motion of an oscillating air-track glider using the IR camera
- Drawing displacement-time graphs using the IR camera
More details can be found on the Guide Page of this site.