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Thread: Kind of off topic timing electronic type of thing.

  1. #21
    ATX Mental Case Cool1Net6's Avatar
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    Default Re: Kind of off topic timing electronic type of thing.

    I'm just a budding CSE major, but I see 4 sets of IR sensors. The first 2 IR receivers are placed at the start, and are spaced from each other a few inches or so. These are used to line up cars evenly and accurately, and to make sure every race starts at the same location. The other 2 are placed at the finish line, 1/4 mile away from the start sensors, and spaced from each other similarly to the start line. All sensors are placed near the ground, and only "see" a car's tires.

    When a car starts the race, the first beam is broken but the second is still in tact. You start timing as soon as the second beam is broken, and you stop timing as soon as one of the beams at the finish line is broken. I put 2 IR sensors down there to solve the "the cars move too fast" problem.

    All of these sensors would hook into some computer system and as long as they all act as switches, I don't think it would be too difficult to program for them. If the sensors are quick enough, you could potentially use the 2 finishing sensors to calculate ending speed, but I am unsure of the accuracy.

    And if your using WiFi N, you could always use some sort of cantenna to point your signal down to the start to help with signal strength.

    My $0.02.

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  2. #22
    Post count? Get over it. Drew's Avatar
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    Default Re: Kind of off topic timing electronic type of thing.

    Right.

    For experimentation purposes...

    Shopping list:

    Phototransistor or several (cos I will break one).
    Serial plug terminal.
    Bunch of wire.

    Oh poo. I'll need some software.....

    Stuff it, it's late, I'll think on it more in the morning.

    Oh, and thanks guys. CB? You're a star. + reps all round for the help so far (and that left to come..).

  3. #23
    Fox Furry crenn's Avatar
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    Default Re: Kind of off topic timing electronic type of thing.

    My thoughts is to use a simple method... sort of.

    You know how radar guns (the type police use to book you) measure speed by calculating distance over time? Using that principle except having the sensor being triggered when something comes closer than the set distance (aka starting line) and then trigger a 'stopwatch'. It waits for the 2nd distance (finishing line) to be reached and stops the stop watch. Using that, you can also measure the acceleration, average speed etc.

    Just a rough idea.
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  4. #24
    I got rid of my floppy disks Xpirate's Avatar
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    Default Re: Kind of off topic timing electronic type of thing.

    This depends on how inexpensive the event is going to be. Official ET slips at a drag race give you your reaction time, 60 feet time, 1/8 mile time, 1/4 mile time, trap speed, etc. If you need to provide all this, the $ spend might be worth it depending on how much $ the event will generate.

    If the event will just measure the time from when the light turns green to the time the lazer beam is broken at the end, you'd only need one computer that controls the tree lights and reads the lazer beam at the end of the track. You would also need some lazer beams to stage the cars as well. All they would need to do is activate the staging lights.

  5. #25
    Post count? Get over it. Drew's Avatar
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    Default Re: Kind of off topic timing electronic type of thing.

    Quote Originally Posted by Xpirate View Post
    If the event will just measure the time from when the light turns green to the time the lazer beam is broken at the end, you'd only need one computer that controls the tree lights and reads the lazer beam at the end of the track. You would also need some lazer beams to stage the cars as well. All they would need to do is activate the staging lights.
    BINGO!

    All we need is exactly that.

    These events will never make me rich... thats why something cheaper must be found. Oh, and as it's quite informal.... stage lights may be a bit much.

    I would happily sacrifice some ultimate accuracy for consistency, and print outs wont be necessary. We're not talking a 50,000 prize pot or 6 second cars.

    In fact, stuff it, heres what it is... and why I've been less than over-active on the forums of late..... www.driftwest.co.uk ... my new baby. And yes, I know the paypal buttons are broke.

    It's just a timing system that keeps people happy that on the same track a 15 second pass beats a 16 second pass by a 1 second margin. Make sense?

    Here's what I'm thinking at the mo...



    A = Computer (duhhhh).
    B = Start lights (bulbs or LEDs, probably LEDs).
    C = Laser/ infrared/ whatever reciever.
    D = Laser/ infrared/ whatever emitter (battery powered for less wires?)

    I'm thinking staging will be manual, with a line in the road and a marshall.

    A button is pressed on the computer, which sets the start lights off on a pre-programmed sequence (something like yellow, next yellow, next yellow, green) and on green the computer starts timing.

    When the car breaks the beam at the other end, the timer is stopped and the time recorded.

    Then the system could perhaps be reset by another button press from the computer.


    So I need.....

    Loads of bulbs/ leds for the get ready/ go lights.
    Connector to computer for lights.
    Timing beams for the end .... end.
    2 emitters & 2 recievers.
    About 1400 miles of wire (is signal loss going to be an issue here?).
    Some amazing DaveW stylee program to run it all.

    Anyone spot any obvious flaws before I go spending monies I haven't got?

  6. #26

    Default Re: Kind of off topic timing electronic type of thing.

    Quote Originally Posted by Drew View Post
    BINGO!

    All we need is exactly that.

    A = Computer (duhhhh).
    B = Start lights (bulbs or LEDs, probably LEDs).
    C = Laser/ infrared/ whatever reciever.
    D = Laser/ infrared/ whatever emitter (battery powered for less wires?)

    ...

    So I need.....

    Loads of bulbs/ leds for the get ready/ go lights.
    Connector to computer for lights.
    Timing beams for the end .... end.
    2 emitters & 2 recievers.
    About 1400 miles of wire (is signal loss going to be an issue here?).
    Some amazing DaveW stylee program to run it all.

    Anyone spot any obvious flaws before I go spending monies I haven't got?

    No flaws all looks good. Signal loss just means you'll need a higher power supply on the relayed circuits - thats one of the reasons I was suggesting a wireless Lappy link to transmit the stop signal.

    You will need a serial port In/Out Controller/Relay board or something similar. You could make one. I have found one example in the UK for you that costs 65 constructed. It has 8 output channels through relays (one for each of the lights! - and offers you those extra channels for the bright ideas that are sure to flow) and 4 opto-isolated digital inputs (whatever the f that means). Maybe there are simpler cheaper versions with fewer channels but this doesnt seem bad:



    It can be operated at the end of anything up to a 100 foot long serial cable offering you extra flexibility in installing your setup. It comes with software or allows addressing the port through command line etc etc very flexible.

    Edit: Drew, I just had a long chat to their tech support guy. Opto-isolation just means the input signal is fed into an digital-optical relay chip that isolates the input circuits from the serial port meaning no blown up Lappy's. This board is spot on. You feed the IR sensor into a relay put a twelve volt battery on a wire that makes a circuit with the board and when the IR is triggered the serial port will register the event. You will need to check that there will be a distinguishable signal with 12V on a half mile loop of cable. The board happens to run off 12V too. So a bunch of car batteries can maybe power the whole setup.

    You can use terminal emulator I think he said to control it so if you can launch and control that from your App Dave its all done and dusted - the control commands are sent with the board and the boards own software is downloadable from the seller for free. Otherwise working out how to address the serial port and board won't be that hard would be my guess.

    Edit2 The other reason I had suggested using Lappy's to send the "PassFinish" signal was that loads of cable trapsed around is a health and safety issue.

    Plus: The above boards output cicuits can control AC circuits up to 250V or DC circuits (didnt ask the max). this is perfect. A few bright 10mm LEDS behind each lens is going to make a very visable set of Lights for the start line. You will only need to run 3 - 12v through these lines and again that cuts the health and safety risk if none of your long cabling has a high voltage. The problem is that long cables lose more power at high Amp to Volt ratios than at high Voltage to Amp ratios. This is why long distance power cables are typically high-tension (i.e voltage) and carry a relatively smaller current at several thousand volts, transformered down for domestic supply at substations.

    Matthew
    Last edited by Crazy Buddhist; 08-15-2007 at 11:26 AM. Reason: pellings

  7. #27
    Post count? Get over it. Drew's Avatar
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    Default Re: Kind of off topic timing electronic type of thing.

    Oh

    My

    God!

    An entire bucket of thanks go in your direction CB.

    Do you have a link for that box of magic?

  8. #28
    Post count? Get over it. Drew's Avatar
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    Default Re: Kind of off topic timing electronic type of thing.

    quasarelectronics.com.....

    What a n00b....

    That place is geeek/ nerd heaven!

    But I can't find the actual one pictured

    Link please

    :edit:

    What a pillock.

    I just clicked the pic.

    Knobhead.
    Last edited by Drew; 08-15-2007 at 02:26 PM. Reason: I am a proper moronic piece of crap :(

  9. #29

    Default Re: Kind of off topic timing electronic type of thing.

    Quote Originally Posted by Drew View Post
    Link please

    :edit:

    What a pillock.

    I just clicked the pic.
    Grasshopper, you are learning well. Keep your eyes open.

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  10. #30
    D'Oh
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    Default Re: Kind of off topic timing electronic type of thing.

    reply
    I'm back, had some ISP problems.. Seeing where this is going... well, it is good to know there are lots of pre built stuff that others have come up with.. Ain't I a noob.. A noob filled with imagination tho

    Also, CB, you are absolutely right... I didn't think about the distance at first.. Long cables... BAD. Still, the demo I saw was pretty accurate... Like 6 decimals accurate.

    I am studying to become an engineer (electronics) and am far from it. But I think I have the right mentality: think, create, and go back to the drawing board... Repeat So, I thought about this and overcoming distances: one laser and one sensor installed at a right angle. Add 3 90 degrees mirror systems and point the light beam in a circular fashion, as far as you can. At the first interruption of the circuit (e.g. start, the capacitor starts loading). Then, after several seconds pass, the circuit is interrupted again at the finish and the capacitor is cut off. Measure the voltage and do some simple math and you get the time interval. Circuit could be really fast as it employs few parts (some logical gates and maybe a latch or two), so errors are reduced. Also, by using a separate calibration circuit, which uses a timing IC (e.g.:LM555) to give 2 pulses at a known time distance, you could extrapolate the law at which voltage rises and choose a suitable capacitor for the desired track and known car times. The voltage is fed to an Electronic Voltmeter and converted in an ADC by the known law in a number>> the time. I am not saying this should be built, but this is sort of what I meant the first time. No advanced math or physics (at least not here). Just an idea

    Oh, the grasshopper thing applies to me too If I said something stupid (and someone noticed), I apologize and quickly hide in the corner, wearing a nice pointy hat

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