Crash Sled control

[DAQ_Newbie]

Hi,
 
In short my project consists of controlling a sled by
(1) launch a sled by releasing a solenoid pin (TTL signal)
(2) start acquiring data from a bunch of accelerometers by triggering a snap switch and also triggering high speed camera at the same time
(3)  apply brakes (TTL sig to brake actuator) when sled bounces back thru 2 sets of optos. Oh measure the speed of sled when it travels thru optos the first time.
 
Ive currently have a pcie 6259 DAC and an SCC 68 and cable on the way.
I am hopeless with electronic circuit and need some advice on how
 
(1) circuitry bet the optos and DAQ card for noise reduction
(2) circuitry required bet the solenoid pin, relay and DAQ card
(3) circuitry required bet the brake actuator, relay and DAQ card.
 
Thanks heaps
Don

[mallorim]

Hello DAQNewbie,

 

Welcome to the forums. I am a bit unclear as to the abbreviations you use in your post. When you say "bet" do you mean between? And by optos do you mean some sort of optical sensor?

 

A great resource for wiring external connections so as to remove noise is the <a href="http://zone.ni.com/devzone/cda/tut/p/id/3344" target="_blank">Developer Zone Article: Field Wiring and Noise Considerations for Analog Signals</a>. With regards to how to connect the solendoid to your DAQ card, a better description of the physcial set up, or perhaps an attached image might help to describe your system and let me make a better suggestion as to what you would need to connect all of this together.

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Regards,

Mallori M.

[DAQ_Newbie]

Hi Mrs Mallori,
&nbsp;
the sled system consists of a ramming a&nbsp;child dummy&nbsp;(strapped on a child seat) into a barrier to simulate a car crash. The sled is propelled by cables (under tension) and is released by pneumatic cylinder connected in shear to its rear. It is a pin release systen using the&nbsp;cylinder's shaft as the pin.
&nbsp;
once the sled is released, it passes through two sets of optical switches (Deep gap slotted optical switch OPB815W by Optek Technology Inc.). The sled's velocity can then be found by determining the time interval in the on/off of the optical switches TTL signal level.
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The sled on its pathway also&nbsp;hits a limit switch which triggers data acquisition (Analog inputs - 4 accelerometers from dummy and 1 accelerometer from sled) and a High speed digital camera.
Once the sled bounces&nbsp;back through the optical switches, sled's brakes are activated ( standard motorcycle brakes- electrical actuator). I wanted to know an easy&nbsp;way on how to control the braking - meaning reducing the braking power to slowly let the sled come back.
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hope this&nbsp;provides a better &nbsp;picture of the system.
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kind regards
don

[tnek]

Hi Don, It sounds like you have a good idea of what you want to accomplish. The method to control the braking will be dependent on the capabilities of the electrical actuator. One way to vary the amount of braking may be to use <a href="http://digital.ni.com/public.nsf/allkb/294E67623752656686256DB800508989?OpenDocument" target="_blank">pulse width modulation</a> which can can be done using a counter output from the PCI-6259. Again, this is all dependent on the actuator. Regards,KentApplications Engineer

[DAQ_Newbie]

thx for your reply kent, im looking into the pwm right now.
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one question, i was thinking of triggering the brakes the old fashion way, using ICs as i was thinking that the system might not respond as quickly as required&nbsp;as it is acquiring and transferring data at the same time bearing in mind that the application is running under windows.
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[tnek]

Hi Don, That is a good point, depending on the scope of your project you may want to check out a few <a href="http://www.ni.com/realtime/" target="_blank">real time solutions</a>. Regards,KentApplications Engineer