First test results on much lower cost Gyros
I purchased some dual axis gyros from Gyration.
they are about $35.00 each in singles.
They have I2C digital outputs for input voltage, two gyro axis and temperature.
I built a small PC to test them using the MaxStream Xbee radio
and a Netburner MOD5213 for the CPU.
In the picture below:
- The 40 pin dip is the Netburner,
- The Blue part the Xbee radio.
- The Silver Cans on the top left the Gyros.
- The unit on four standoffs at the top middle is a 2 axis accelerometer.
- The loose gray wires are used to put code into the netburner.
I mounted the whole assembly to my CNC rotary table and did some rotation testing.
The results are shown in the graph below.
I'm plotting the 4 gyro outputs, in the yaw axis.
Two of the gyro outputs should be in sync, and two of them should be stationary.
The first things I notice, the noise on the gyro axises vary alot from gyro to gyro.
The rotation is much noiser than the zero, this may be because my platform is stepper driven.
I'm going to buy an ac syncronous clock motor and try that as well.
The order of events from left to right
- Everything stis still till about sample 1581
- Then a slow 360 degree rotation lasting 2 minutes. (I type the wrong Gcode it was slower than I wanted)
- Followed by a 360 rotation back the other way at 720 deg/min
- 2 180 degree rotations both ways twice at 1440 deg/min. (I'm not certain the table actually goes this fast)
- 180 degrees both ways at 720 deg /min
- 90 degrees both ways at 1440 deg/min
The Raw Data coulmns are sample number, gyro1a, gyro1b, gyro temp, x acell, y accell,gyro2a, gyro2b, xacell,yacell
The raw data: Rotate.csv
The Test unit Schematic.
The code that runs on the MOD5213
The code that runs on the PC and listens to the serial port decoding inputs.
The Protel design files for the test board.
Please Note that the Schematic and PCB do not match
The schematic has a correction on pin 6 of U2,
this correction is not on the included PCB design file.
If you look real closely in the unit pictures you can see the jumper on pin 6 of U2
The PCB design files also has the hole sizes for the XBEE radio too small.