=============================================================================================================

Thursday, July 17, 2008

Rate or Position measurement using Solid State Gyroscope


updated:14/08/08

Hi friends,
here is a circuit to measure rate of a rotating object using solid state gyro ADXRS150 (used here is DIP sized evaluation version). this circuit gives output of -10v to +10v for rate upto 80 deg/sec in both the directions (i.e. -80 to +80 deg/sec). A direction o/p logic signal is also there to feed to microcontroller. Temperature of gyroscope also can be measured with onchip ADC of the microcontroller like ATmega32 (describd in previos post), which can be used for temperature compensation of the gyro o/p.

find the detailed datasheet of ADXRS150 here:
ADXRS150 Datasheet

11 comments:

Shlomo (msj121) said...

I saw your question on the electronic forum about using the gyro for longer period of times as a position measurement. I don't have an account there so I am posting here.

I don't think its possible; or rather easy to do. I would suggest a next step to look into combining an accelerometer and a gyroscope. This way between the two of them they can "correct" each other and get better values. Errors might still build, which makes integrating not fun at all.

Good luck with the project. I personally am looking into using IR detectors for location information as this method seems to complicated for me.

MSJ

CC Dharmani said...

Hi MSJ,
thanks for the suggestion.
By IR detectors you must be meaning to use rotary encoders or such other encoder for getting position. The method of using gyroscope is somewhat complicated, accepted, but in my project mounting of the sensor is allowed only on the top surface of the rotary platform, no interface between rotor and stator. So I had to go with this method.
Right now I'm trying an accelerometer for another project. I'll surely look for a way to use it along with gyro, as you said, to make corrections in the drift for longer durations.
Thanks.

Aaron Ryan said...

I'm not sure if you have solved this problem but there are some decent leas to answering the drift problem using an accelerometer/gyro combo and integrating the data with a Kalman filter. There are also ready made code packages in C if you're using the Atmel.

Check out this page:

http://geology.heroy.smu.edu/~dpa-www/robo/nbot/

I'm working on something similar right now and the learning curve is steep for me...with very little experience in electronics, but what fun!!

bringFire@gmail.com

CC Dharmani said...

Hi Aaron,
that's really a very informative link. Thank you. I'd like to give a try balancing the inverted pendulum!!
In my gyroscope problem, I've tested the VCO and other circuits connected for processing the gyro output. VCO was perfect but there were variation in the opamp outputs. So I've replaced them with better ones (more immune to noise).
Also, the gyro PCB is enclosed in metallic casing, which has further reduced the drift. So, for the moment it's within specification.
I'm still working on accelerometers on different project,so got busy there. I'm going to use it with the gyro shortly for my experiments, though I'm afraid of the integration with Kalman filter! :) It looks like lot of mathematics is involved!!

Thanks.

Anonymous said...

Hi Dharmani,
I really like your site. I was a fan of the AT89S52 until recently I started to use the AVR series. AVR rocks! and your website too !

Keep up the good work !

regards,
Seemanta (seemanta at g m a i l dot org)

CC Dharmani said...

Hi Seemanta,
Thanks a lot for the comment!

Nitesh said...

recently im working on a robotic arm project which involves use of adxl150 gyro. can u sujjest any place wr i can get this mems device. ive tried analog devices but failed.

CC Dharmani said...

Hi Nitesh,
analog devices has put the ADXRS150 in obsolete list. They've come up with it's replacement ADXRS163, check out here:
http://www.analog.com/en/mems-and-sensors/imems-gyroscopes/adxrs613/products/product.html

Nitesh said...

can u please sujjest some place where i can get adxl150 gyro. ive tried to get it from analog devices but failed.............

CC Dharmani said...

ADXL150 is an accelerometer, not gyro. That one also has got obsolete,
the replacement is ADXL78 accelerometer.
Check out here:
http://www.analog.com/en/mems-and-sensors/imems-accelerometers/adxl78/products/product.html

Praneeth said...

Hi sir, this is praneeth from GITAM University... we're working on your paper in the isoi journal i.e.Angular position measurement of a rotating platform using a solid-state gyroscope...
we would be really honored if you could please assist us with the said...