Rustam's techno-feed

In this post I’ll try to investigate what signal is produced by WiTilt accelerometer/gyro controller when it is immovable, whether it is noisy or not.
I placed WiTilt (3-axis accelerometer and gyro controller) on a table and collected data from it. I got 350 samples of raw x,y,z,r (accelerations along 3 axes and speed of rotation) measurements from motionless controller. WiTilt was put on a surface in a way that z axis was directed upward. So, collected data from z accelerometer shall give acceleration of 1g and measurements from x and y axes shall give 0g value. Analyzing the data in Excel, I received the following results (all measurements are in raw ADC values).
Read more…

Here is the demonstration how tilt is calculated from acceleration. We assume here that 3-axes accelerometer experiences only 1g gravity acceleration.

Read more…

A circular buffer, cyclic buffer or ring buffer is a data structure that uses a single, fixed-size buffer as if it were connected end-to-end. As it is fixed-size buffer, when it is full it starts to overwrite the oldest stored items with new ones. The logic is that recent data is more important then old one.

Circular buffer for plocessing n last samples

Several months ago I purchased wireless accelerometer/tilt/gyro controller called WiTilt. This is the latest wireless accelerometer from SparkFun. It cost me 219.15 USD. In few days after purchasing it was delivered to me and I started my experiments. Here is the short specification of the controller:

• MMA7260Q 1.5/2/4/6g triple axis accelerometer sensor
• MLX90609-150 single axis gyroscope sensor
• Roving networks Bluetooth Wireless Module: Class 1 with 100m (330′) line of sight (30m or 100′ indoor use)
• Tilt output in degrees
• Lithium Polymer battery provides roughly 12 hours of run time

Read more…