MEMS Accelerometers
I recently messed with some accelerometers in order to cancel out dead weight in a load cell application. These MEMS (microelectromechanical systems) devices are really handy. They are incredibly small, they have very modest power requirements, and are typically in a standard IC package. The device that I ended up using was a Freescale MMA1220EG. It offers an on-board amplified output and only requires three external components. It uses 5VDC at 5mA, and has a +/- 8g range. The 0g offset is 2.5V and moves from that point at 250mV/g.
I built a simple PCB that mounted the accelerometer and a filter along with an op-amp as a buffer to drive the output and send it down a run of wire. It worked so well I’ve been trying to think up something else to put one on.
4 Comments to MEMS Accelerometers
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Do you have schematics for these projects? I would like to play with them. Thank you for your time.
Dr.Booth@gmail.com
http://bomarc.org
I used the reference design from the datasheet, you only need to supply an input bypass capacitor, and an output RC filter based on the frequency you are interested in.
Hey,
I was just looking at your cnc machine and then your general blog and saw this post. What if you mounted accelerometers on the head of the cnc machine. Wouldnt that add positive positioning feedback without messing with all the nasty encoders or using servos or all the other complicated means of confirming position.
Am I right or wrong? Could you email me if you try it (i built a simple cnc machine as well). Accelerometers on cnc heads could revolutionize the industry….
Assuming you could filter out vibration enough to get decent accuracy, you would develop error over time that would preclude accelerometers. You would need to re-zero the machine frequently. Encoders are probably a better choice.
I was also reading recently (Electronics Design magazine I think) that MEMS accelerometers are really noisy. I can attest to that because the accelerometer I used in that post is almost unusable without filtering.