Accelerometer IC for aerial vehicle?

[DigiTan]

I'm working through the planning stages of a micro UAV project. Part of the vehicle design requires the use of 2 to 4 accelerometers to estimate airspeed and correct pitch and roll. Sometime last spring, I heard someone mention from an earlier forum here that there are accelerometer ICs availible on the market that might fit the application. I've done a little searching through Digikey, but most of the designs use hard-to-solder chip packages like LCCs and CERPAKs--and I'd rather not work with these if there are other options :lol: . I was wondering if anyone here might recommend any similar accelerometers.

I don't need anything too elaborate. Basically, I'm just looking for anything in a DIP or SOIC package. I'd prefer dual-axis measurements, but single-axis systems will work too. It has to be sensitive to small movements so it should be able to detect dynamic accelerations in the 0.001G range. I'd also prefer digital-only outputs so I can limit weight, but other encoding types are acceptable. Any recommendations?

 

[Oznog]

Sure:
1. Analog Devices has a good series. ADXL202 is a good device, +/- 2g.
2. DIPs are obsolete. Frankly, industry does not want them and no modern devices are likely to be available. LCC is common. So get an eval board with the proper pads, etch your own, or send it out for mfg. It's not that expensive these days.
3. I don't think there's any way to get 0.001G accuracy. They're inherently noisy devices! Plus the offset error and its drift are far, far larger than this. You could do massive oversampling or filtering to try and ditch the noise, but it can really slow down your system and will do nothing for the offset errors.

 

[DigiTan]

8) Sounds good! I'm thinking this whole inertial navigation idea is just an accident waiting to happen so I'm going to concentrait much less on that area. From the looks of things, the ADXL202 is probably my best option.

I just have a few more questions. If I wanted to send my PCB out for manufacturing, where and how would I do it? Are there any special requirements involved?

Finally, I just have one last (unrelated) question. On the ADXL202 spec page they make a reference to something called "glue logic." What is that exactly?

 

[Styx]

Sure:
2. DIPs are obsolete. Frankly, industry does not want them and no modern devices are likely to be available. LCC is common. So get an eval board with the proper pads, etch your own, or send it out for mfg. It's not that expensive these days.

DIPs are not obsolete !!!!!.
about 50% of IC approved for aerospace use are CERDIP for the simple fact that ceramic is the only material to encapulate silicone to cope with the extreme temp range.

There a quite alot of modern chip that get made in CERDIP (national Semi tend to knock out there chip always in this package). Sicne the actual die can handle the temp range it is the packaging that cannot handle the stress.


True in commecial industry SO is more convenient

 

[crust]

Finally, I just have one last (unrelated) question. On the ADXL202 spec page they make a reference to something called "glue logic." What is that exactly?

Glue logic is just a term used to represent the other parts you need to use such as 74XX, inverters, etc.

 

[DigiTan]

Ah, so that's what it's called. I always thought they'd have some name for that technique.

Well I guess it's settled then. Tomorrow I'm ordering a ADXL202JE (commercial spec) through Digikey for about 15 U.S.D.--unless I can find one cheaper elsewhere. Meanwhile, I'm going to try to develop a working decoder for it. Thanks for the help!

 

[Oznog]

Well I guess it's settled then. Tomorrow I'm ordering a ADXL202JE (commercial spec) through Digikey for about 15 U.S.D.--unless I can find one cheaper elsewhere. Meanwhile, I'm going to try to develop a working decoder for it. Thanks for the help!

Cheaper? Go to Linear and Request Samples... free. That cheap enough for you?