Recent content by ConnorM

Yes I think I managed to fix it! I’m not quite sure how to convert from digital to analog, I was able to find a lot about how to convert from analog to digital though. Would I just apply a reverse bilinear transform to the Z space transfer function?

Realized I was looking at a digital filter and not an analog filter. It was in Z domain so the poles were contained within the unit circle. Did my best to replicate the digital filter response with the analog filter I made.

I am a student trying to design a Butterworth LPF to meet the class 1000 specifications, by SAE J211 (https://law.resource.org/pub/us/cfr/ibr/005/sae.j211-1.1995.pdf). My sensor is an ADXL377 accelerometer with analog output. My filter requirements (from J211) are fp = 1000Hz (Pass band...

The dummy will have 3D printed skin, a helmet on, and I expect the bike will absorb some impact energy (The relative velocity between the bike and car will only be about 10km/h for the majority of testing), so I don't expect very large g-forces that may occur in say a metal on metal collision...

You are helping me out a lot haha, thank you. The aluminum will be rigidly supported. This is the piezoelectric sensor that I am looking at, A502 (https://www.tekscan.com/products-solutions/force-sensors/a502?tab=specifications). Tekscan, the manufacturer, suggests some ways to deal with shear...

I predict that this accelerometer's range (+/-200g) will be quite a bit larger than the actual g-force range in my crash test. I think this because the car will be traveling at 30km/h and the bike at 20km/h, the collision will be a rear collision so deltaV=10km/h. This is a relatively low...

After doing some more reading I think that an ADXL377 accelerometer (1600Hz X and Y) should be enough for my case. I was looking at "Vehicle Crash Mechanics", by Matthew Huang, and the SAE J211 standard for electronic sensors in impact tests. These resources talk about "Classes" for...

Problem I am designing a force sensing system with piezoelectric force sensors to determine the impact force on an object during a collision. The sensor will be placed between an aluminum block and either a TPU or PLA 3D printed "cover". The cover will be 5cm thick...

Thank you. I'll do some reading then and post back with any questions.

I am trying to decide on an accelerometer to use that will help me measure the g-force that a crash test dummy’s head experiences during a car on bicycle collision. The dummy will be mounted on a bicycle and launched at 20km/h, it will then be struck from behind by a car driving at 30km/h. I...

Oh thank you I have been reading about Nyquist Theory and you finally clued me into where the filtering aspect comes into play. This sensor can output 20 kHz but I can cut this to 5 kHz via a LPF, so I can sample at 10 kS/s for a full reconstruction of the analog wave. So this would this ensure...

10 kS/s is the specified minimum sample rate that sensors in crash test dummy’s should be sampled at. This is a design project through my school and we are trying to get as close to this sample rate as possible. Also, 10 kS/s will give us some assurance that the peak acceleration was captured.

So for my situation, - I am looking to measure the acceleration of a crash test dummy’s head during a very brief impact (15milliseconds). - I want to be able to measure the accelerometer at 10 kSamples/s - The current accelerometer that I am looking at measures +/-150 g’s with a bandwidth of...

I’m planning on using the ADXL375 (200g/3200Hz Bandwidth) or ADXL1001 (100g/11,000Hz Bandwidth) to measure the peak accelerations in a crash test dummy’s head during a bicycle/car crash. My goal is to sample at atleast 10,000 S/s using either a Teensy 3.6 or a Rasp Pi3. The dummy will be...

I am a fourth year biomedical and mechanical engineering student and my final project has to do with designing a crash test dummy. The end goal is to mount the dummy on a bicycle and launch it at ~20kh/h, then it will be struck by an automobile driving at ~30km/h. Various different impact...