Tuesday, June 3, 2008


I've made a youtube video of the mouse:

As you can see, normal mouses are much better for normal usage. Maybe another GUI paradigm would fit like a glove to an accelerometer based mouse. Wii's games certainly do :)

Theoretically, one could calculate the 2D position of the mouse with the XY acceleration signals, given that they are perpendicular to the gravity axis. The problem is that current MEMS accelerometers, well, suck, i. e., they have significant noise and drift. To calculate position, you need to integrate the signal (twice) , and integrating a very small drift leads to bad results. Plus that mouse wouldn't work in inclined surfaces.

With a 3-axis accelerometer + a gyroscope it would be possible to workout a nice 3D motion sensor (IMU, kalman filter). If you know where to get a cheap gyroscope please comment :)

My mother told me that the kid didn't get along very well with the mouse. He was very impatient and got annoyed at every mistake. Maybe after some training he can get better at it. I've recently found this, and I'm going to suggest it, at least he can use it without special equipment.

I hope this information was usefull to anyone. If you have any questions, fell free to ask through the comments or francisco.silva@REMOVETHISalunos.fc.up.pt


Anonymous said...

Very nice project.
a very cheap (under 15Euro incl shipping on ebay) 3 axis gyro is the wii motion plus .i have tested the nunchuck+ motion plus with the bus pirate. it works but now i will try to use them as mouse on an pinguino board, programming is in progress.
When ready i will publish the project

Oinquer said...

Hello, are you portuguese? im trying to connect a nunchuk like this but i use a IDE called PIC SIM IDE from Oshonsoft, it has support for I2C but im not being able to read nunchuk.
just FF from reading.

Gabriel said...

quote: "The nunchuck 5th byte is a bit strange: when the Z button is down, it's first 2 bits are 0x01, when C is down, it's 0x00!"

I had the same behavior when I was not decoding the data, you need to XOR each byte with 0x17, then add 0x17. Note that this has to be done to all bytes, not just the 5th byte.

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