There is no IMU forum so I didn’t know where else to post this.
I am using the 6 DOF razor that Sparkfun makes as part of an IMU that I am designing. On it is the LY530ALH gyro and I have been having some problems with this chip. The chip is giving me bad data as it gives voltages way above the zero velocity voltage then approaches the maximum voltage and oscillates around that. I have tried to play with the control pins (ST, PD, HP) for it with no luck.
Is there a certain way to set those pins for the chip to work properly or is there something else that I am forgetting to do with it?
Thanks
mlb5005@psu.edu:
On it is the LY530ALH gyro and I have been having some problems with this chip. The chip is giving me bad data as it gives voltages way above the zero velocity voltage then approaches the maximum voltage and oscillates around that. I have tried to play with the control pins (ST, PD, HP) for it with no luck.
I am having similar issues with the razor, just with the LPR530 chip (x & y axes). Voltages oscillate around Vref on the imu board (1.23V), I checked these with a multimeter, so it’s not my adc sampling routine. The accels and z gyro are fine (for a few minutes ~20min, but then it seems the z accel and z gyro values get coupled together, another issue, may be related). I’m starting another post in the Projects forum to try to get some technical help.
I had the same problems… then I realized that it was a problem with the ground… fixing that, solved the problem for me…
good luck…
How did you fix the ground connection?
Another known issue with the gyros of this board is that the BOB has LP and HP filters on it and this causes the values to eventually have a bias that depends on the past values of the angular rate… there’s some posts about that in here(the posts are for the 9DOF but the problem is the same)… I just don’t remember where… 
Roicker:
Another known issue with the gyros of this board is that the BOB has LP and HP filters on it and this causes the values to eventually have a bias that depends on the past values of the angular rate… there’s some posts about that in here(the posts are for the 9DOF but the problem is the same)… I just don’t remember where…
what’s wrong with having both lp and bp? makes a bandpass filter
well, the implementation intended to eliminate slow drift of the signal, but it didn’t… instead, you get a signal that doesn’t return to zero with a changing offset… that can’t be easily substracted…
Roicker:
well, the implementation intended to eliminate slow drift of the signal, but it didn’t… instead, you get a signal that doesn’t return to zero with a changing offset… that can’t be easily substracted…
yeah i know the intention of bandpass filter is to remove noise to eliminate drift. but how exactly does it cause the signal not return to zero? was some bias frequency filtered away? does anyone have a signal processing explanation? thanks =)
I’m really not that good on analog filters, but if you search the forum you will find posts about it…
The circuit was designed by Jordi from DIY Drones, and after he realized there was a mistake, he recalled the units sold by them (ArduIMU)… unfortunatedly for those of us who bought the 6DOF Razor.
Anyway, search the DIY Drones forum, there is a post on how to remove (and which ones) the LP filter…