Posted by Magellan on September 26, 2009 at 12:39pm
With the recent release of the source code for the ArduIMU, I hope to port it for use with some sensors and an arduino that I have. Here is a picture of my current setup.
Note: I need to finish connecting the gyro on the left.My question is, does it matter how closely the gyros are placed to one another? Most designs I have seen have them surrounding one another. My setup isn't able to do that since I am using a very small breadboard.What sort of problems (if any) will I run into with this layout?
You need to be a member of diydrones to add comments!
take ADXRS401
Linear Acceleration Effect Any axis 0.2 °/s/g
suppose the gyro is subject to quite noticeable acceleration of 1G due to the centrifugal force, just because the plane started spinning madly.
this accounts to 0.2degsec error, out of full scale =2*75degsec. this is 1/750 of the measurement range.
if using 12 bit ADC you could see a change of reading by 4096/750=6 units worst case
Looks scary, almost noticeable.
But who would generate such acceleration? a gyro misplaced by 10cm from the center of gravity will be subjected to 1G centrifugal forces only during fast rotation. accel_centrif=omegarad^2*r
omega_rad=sqrt(accel_centrif/r)=sqrt(1/0.1)=sqrt(10)
omega_deg=omega_rad/PI*180=sqrt(10)/PI*180=181 degsec
therefore from a plane rotating at 181 degsec (note: already 2 times above what gyro can read) you can expect 1G on gyros placed 10cm away from COG, giving 6 units error on 12bit adc imu using ADXL401.
if the autonomous flying object is rotating that fast, you are usually in much more serious trouble already.
somebody pls verify the calculus and assumptions.
my proposal: keep them far away of each other and avoid shorts.
Replies
take ADXRS401
Linear Acceleration Effect Any axis 0.2 °/s/g
suppose the gyro is subject to quite noticeable acceleration of 1G due to the centrifugal force, just because the plane started spinning madly.
this accounts to 0.2degsec error, out of full scale =2*75degsec. this is 1/750 of the measurement range.
if using 12 bit ADC you could see a change of reading by 4096/750=6 units worst case
Looks scary, almost noticeable.
But who would generate such acceleration? a gyro misplaced by 10cm from the center of gravity will be subjected to 1G centrifugal forces only during fast rotation. accel_centrif=omegarad^2*r
omega_rad=sqrt(accel_centrif/r)=sqrt(1/0.1)=sqrt(10)
omega_deg=omega_rad/PI*180=sqrt(10)/PI*180=181 degsec
therefore from a plane rotating at 181 degsec (note: already 2 times above what gyro can read) you can expect 1G on gyros placed 10cm away from COG, giving 6 units error on 12bit adc imu using ADXL401.
if the autonomous flying object is rotating that fast, you are usually in much more serious trouble already.
somebody pls verify the calculus and assumptions.
my proposal: keep them far away of each other and avoid shorts.