We used the setup below to test the magnetometer. We uploaded code to put the data from the magnetometer out through the serial monitor, and found that the sensor is responsive to the presence of refrigerator magnets.
Saturday, April 26, 2014
Magnetometer Test
We will use a Triple Axis Magnetometer Breakout - HMC5883L
to detect magnetic field at the payload's location during its flight.
The magnetometer provides a digital signal representative of magnetic in
three axes, and must be provided with 2.16V to 3.6V.
We used the setup below to test the magnetometer. We uploaded code to put the data from the magnetometer out through the serial monitor, and found that the sensor is responsive to the presence of refrigerator magnets.
We used the setup below to test the magnetometer. We uploaded code to put the data from the magnetometer out through the serial monitor, and found that the sensor is responsive to the presence of refrigerator magnets.
Subscribe to:
Post Comments (Atom)
The magnetometer measures changes in the magnetic field along three axes, x, y, and z, so each axes needs to be calibrated. The team did so by using knowledge of the magnetic field at a given latitude, longitude and altitude provided by an application on the Nation Geophysical Data Center’s website (http://www.ngdc.noaa.gov/geomag-web/#igrfwmm). The lab’s location was used to generate the expected values for the north, west and down component of the magnetic field (as shown in row table 1 and 2). Then the team used a compass to find magnetic north and aimed each axis (x, y and z) in this direction. Then using the same compass the team pointed each axis eastward. The team used a level to put each axis upward. This gave the team three points to calibrate each axis. After adding this calibration to each axis, the team added code to calculate the magnitude of the magnetic field. The team repeated the test done in calibration (result in table 1). Finally the team tested the magnitude of the magnetic field point the x direction north, then 45 degree from north and 90 degrees from north (results shown in table 2). The device manual states the device has a resolution of 5 milliguass or 500 nano Tesla, our results are within this range.
ReplyDeleteTable 1
ReplyDeleteN+ (nT) E+ (nT) Up+ (nT)
Exp 18,886.9 -2,334.3 -50,572.2
X 19,285 -2,983 -51,075
Y 18,455 -1,600 -49,829
Z 19,185 -2,980 -50,135
Table 2
ReplyDelete◦ from N Total Field (nT)
Exp 54,034.4
0 53938.15
45 53676.32
90 53722.11
When integrating the all systems with the PCB the magnetometer was damaged. This was due to an error on the PCB which connected the digital pins to a high voltage. Unaware of this issue we changed out the magnetometer and broke that one as well. We then discovered the problem and fixed the board by cutting incorrect connections and adding new connections with wire-wrap wire. We used wire-wrap wire because the connections were small and this wire takes up little additional space.
ReplyDelete