炉匠请进：如何复制卡车的震荡?

waspking

一直在想有没有办法复制卡车的震荡，但不知用何器件测量震动。
昨天运气好， 狗了卡车震动， 找到一篇文章， 发现有accelerometer可以来干这事。 如是写了个小课题报告。
1）。 用accelerometer测量装蜜蜂的卡车的震动。
2）。 用Treadmill+uneven wheels (on the cart) to reproduce the same vibration (trial and error).
3). after the "vibeerator" (see I already got a cool name for it) is built, one can study how vibration affect bee physiology and behavior.

cool, right? but today thought of asking you...maybe using a treadmill is too low tech? not sure if one can feed the data back to a computer to control a platform (hydraulically controlled?) that shakes just like a truck ride...but it might be too expensive...and it might take a real engineer (like you!) to make such a gadget...maybe there is such an animal already?  

another question is whether the accelerometer can record vibrations for 4 days...it looks like it can store 40,000 data points but samples like 100 times per sec...so might have to record 5 seconds for every hour to save memory...I am assuming that if you record only 1 sec every hr it would not be good since some vibrations/oscillation are longer than 1 sec.

炉匠

你可问对人啦。俺成天跟vibration 死磕。第一个问题： treadmill is a fine and practical way to do it.The problem would be that it has a repeating pattern of vibrations. You might want to have a quasi-random pattern of the vibration. In this regard you might want to use a real track to do the experiment.  Because vibrations on a track can have a wide frequency spectrum, it might be difficult to use a high tech accurator platform to simulate. However, if you only need a platform for small scale experiment (e.g., a bee cage less than 1kg) you can use voice coil 作为accurator. You can use computer generated waveforms to feed into four accurators to simulate the vibration.

For the second question, No problem. 40k data points are only 80KB on a hard drive, 毛毛雨啦。I would suggest you to record 500 data points per sec, continuous for as long as you want. You can later use it for power spectrum analysis.

waspking

谢谢！ 俺就知道您是震动专家。。。

1. I would like to place 2-3 colonies on the platform (about 10 kg each), so total weight is 60 kg.  I thought about the repeating pattern also...not sure if one can modify the treadmill belt itself, (still repeating, but longer duration).  it might not be a problem for studying bees.

2. I think if it would not be a problem if laptop is attached to it...(I might need your help to do the fast Fourier transformation).

This is from a truck driver vibration study:

Whole!body vibration was measured at the driver:seat interface by using a triaxial seat
pad accelerometer (B&K type 4322). The vibration measurements were performed by using a HVLab field computer system. The three recorded acceleration signals for each of the conditions of Table 1 were acquired on a digital computer for 30 s at 500 samples s -1 using 167 Hz anti-aliasing filters.  Frequency weighted accelerations were calculated by using the weighting factors suggested by ISO 2631-1.  A Fast Fourier Transform was performed by using HVLab software  on the time domain data.