Vibration Transducers for Driving Simulation

To see some transducers that are specified from 0Hz to a few kHz, look here. Don't suppose they're cheap, but you may get some ideas. Hope this helps.

[BTW - I think you need to include the word "shock" in your search terms to find the very low frequencies].

Simple is good, mechanical linkage to an eccentric on a motor gearbox of some sort would be my solution, maybe a couple of limit switches... A DC motor gearbox would be nice and controllable, or a stepper motor. Or maybe a disgraced RBS director could do it manually..it would give him something to do while he's idling away his time on an obscene pension paid for by the taxpayer....
Whoops, sorry drifting off....'Nurse...more medication please'
Del

You have it! Simple and effective. Dial right down to one hertz if needed. And cheap.

Don't know what RBS director is, though. We probably have them here in the USA under a different name.

It's a little difficult to answer this since I can't get a feel for the amplitude of the vibrations, what the spectra look like, or the weight you're looking at. But, let me take a crack anyway, while trying to remember Del's admonition to "keep it simple" (BTW, I find a good grape press works well for bankers, even Scottish ones).

Commercial shakers are readily available, but cost a lot, even used. I gather from your post you're looking to do this with a budget of perhaps a few thousand; that's too low, but...

A hydraulic system would do the job nicely, IF you have hydraulic power already avaliable. All you need are a couple of proportional valves/servo valves and some simple cylinders.

If your spectra are not too complex, you can do this in pneumatics, again using proportional valves/servo valves.

Electromechanical actuators would also work, depending on your requirements, though they'll be fairly noisy.

Simple PM servomotors could do the job, but the driver electronics will run perhaps $20k. You might look at the surplus market to see what's available cheap.

I like the idea of the mechanical linkage, but your use of a MatLab type input makes that hard to implement, I think.

Can you tell us more about the requirements, particularly WRT cost?

Hi Nickjd,

I work for an international company that builds simulators.

Check out our site to see a car simulator we built this year: http://www.sydac.com.au

I'm inclined to help you with your problem, but don't really want to give too many trade secrets away...

What you've done so far is good, we've used subwoofers for 20-40Hz mechanical vibrations before (though not in a car sim).

"Powerful speakers can make amazingly high forces so I think that would work"

Don't get too happy with the speaker power - it will lead to problems. As far as LF vibrations are concerned - how big is your budget? We've used hexapod motion bases for train sims, but they can be expensive. Another option is mounting the sim on a platform with AC motor driven mechanisms that induce vibrations (I don't really want to be too specific - corporate responsibility and all that )

On the other hand, if you're looking for a car simulator - we'll give you all the info you'll ever need - if you give us a contract! Send me a private email (via CR4) if you want our contact details, or for an explaination of how we are able to help. Your boss will be impressed with your initiative!

Look forward to hearing from you,

TinTin

Thank you everyone for the input. I am actually unsure of the budget but it is probably in the range of a few thousand euro (but could increase significantly if we have something promising). We wanted something to reproduce real road noise, not just a sine wave. I thought about using a stepper motor as well but I don't think that will suffice unfortunately.

Thanks John for the info on the shock and vibration testing equipment. I will read more about it and see what the costs are.

Ford was using a 6 degree of freedom hydraulic system but it looked quite complicated and very expensive. I would think because of the very fast response times of solenoids they would tend to be more desireable.

TVP45, The spectra looks somewhat like random noise between 5 and 50 hz or so and changes depending on the velocity of the "vehicle" and the road surface. The weight of the seat and user is likely to be 110 kg. These modern car seats are amazingly heavy, plus the weight of a possibly heavy driver...

I like the idea of using some kind of solenoid, or a servomotor because it should be easy to interface with the Autobox. It can have nearly any number of inputs and outputs, digital or analog. Before this, I was unfamilliar with it, but I was surprised how easily you can interface the hardware with a Simulink simulation.

Yeah, I'm not sure what I would do with the bankers but I'm sure I would eventually come up with something useful for them to do lol

TinTin, yes we actually have our own in house hexapod system and use some company's software for the graphics simulation and some of the physics. The hexapod system can do vibrations up to a certain low frequency and feels amazingly realistic. I'm just working on the portable simulator to go to auto shows and the like, but I'm doing the new vibration programming and interfacing it with the existing software through a canbus system. Let me talk to my boss and see what he has to say

You may want to find some old voice coil actuators and use them under the seat. This will not help you with the sound, but you could run a parallel system where you use your subwoofers to your desire but synch the voice coil motors to the specific frequencies you are trying to establish. Sorta like one of those rollercoaster simulators with sound. altcompco@gmail.com

A shaker table is nothing more than a glorified electromagnetic woofer. They come in all sizes and capabilities. I suspect one of these would do the job for you at a reasonable price. Hydraulics are also available, but cost more.

I like the idea of using the voice coil motors too, but my boss didn't want to do that because it's making something work for something it's not intended for. Welderman, how familiar are you with the "glorified woofers"?

I worked in an environmental test lab for 20 years and performed many tests using electrodynamic shake tables (glorified sub-woofers). These tables worked fine for loads of up to a few hundred pounds. If we had to test vehicles and simulate road environments we used larger hydraulic machines. Things have become more sophisticated since I retired. We used to have to do mine and torpedo testing under actual conditions. Now they can simulate those environments with a shaker in a test lab. If you want to perform some tests, I still have contacts at the lab.

A table that could support a few hundred pounds would be sufficient I think, depending on how tall the machine is. Do you know the name of a manufacturer?

We used mostly MB Dynamics shakers however, there are many others including Dynamic Solutions. A Google seach under "electrodynamic shakers" will reveal most of the manufacturers. Renting time at a test lab would be a good introduction to the technology.

A transducer is a transducer. It turns electrical energy into linear motion. The cone of a loudspeaker simply turns that motion into sound.

As a sound engineer in Chciago Illinois for many years, I have produced those low frequencies often. You can do it with a tuned sub box or 1- 18" speaker or 2- 15 " speakers. Try using a tone generator through a electonic x-over and fine tune the Feq. you want. Run through a compressor then max power to your boxes. I built, years ago what is called a W cabinet w/ an 18" JBL speaker. If you could build this cabinet big enough you could mount the car seat right on this box. You would create the sound and feel you might be looking for.

If i can find it? i have drawings of this cabinet and pictures!

send me your e-mail : beiimeiiup@yahoo.com

Mike

stickstuffgrip.com

Actually, we just want to reproduce the vibrations, the sound is more or less taken care of. In the cars that we are simulating there won't be much noise (ie not "cheap" cars ), so we just want to feel the bumps. We actually are using a 12" or so subwoofer with no enclosure, that seems to make some good vibes between 20 and 40 Hz but I bet it would be difficult to make any speaker do 5 Hz without putting a large weight on the cone to make it vibrate more. Plus it has to be fairly compact, being underneath a car seat...

I recently found something in my junk box that may be just the ticket. It is a shaker used in material handling equipment when grain or powder is moved through a funnel or pipe. This device looks like a simple pillow block except that it has no shaft hole. It has an air inlet and outlet. Bolt it to the item to be shaken and when compressed air is blown through it it produces an amazing amount of vibration. The speed of the vibration is proportional to the air pressure. One of these on the seat bottom just might do the trick. I do not know where to purchase one but for the wizards here on CR4 is should be no big feat to find one.

Here is a sketch of a home made vibration transducer. I do not have time now, to cover the details. This works. If you think you may want to play with this Idea, I will send you the IGBT that would do the job. and a schematic and more detailed construction info. I also have the transformer but it is too heavy to send (about 10 pounds)

???? for some reason I can't send picture.

Ask for picutre at glconley@cox.net

First a definition problem, semantics are important in engineering, a TRANSDUCER is usually device which coverts a physical value as for instance displacement in a reference energy used to measure the physical value for instance electric tension or current, an ACTUATOR is a device which does the change the other way.

What you try to find are ACTUATORS. For small displacements and LOW frequencies you could use magnetic actuators which have a higher density of force / area than coil voice actuators. Voice coil actuators are mostly used for high frequencies (and low if required) because of their low inertia which is in high frequencies a major problem.

The mass you will deal with is if I understood it right about 260 kg. Now the force you should have at your disposal depends on the amplitude you want to reach in your frequency domain.