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Complete electronic virgin!

Discussion in 'General Electronics Discussion' started by Eoghan Ryan, May 21, 2016.

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  1. Eoghan Ryan

    Eoghan Ryan

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    May 21, 2016
    Hello.

    I have a basic understanding of electronics. I'm not even related to anyone proficient in this field! But I have an idea, which with help, I know I can build.

    Here's the outline, to track ones speed and the distance away from a moving object and translate such into a small dash mounted audiovisual warning device.

    This is what I think is needed to construct such a device, GPS receiver/tracker to monitor speed, a laser distance meter to capture distance of an object, a micro processor to combine the laser data with the GPS which would trigger the alarm. A data graph (with speed/distance parameters) which would need to be programmed into the processor would enable the alarm triggering points. Is this possible to assemble in a compact device? One could use 12v power too.

    Again, I'm completely green when I comes to electronic lingo and processes so please take it easy. I look forward to discussing this.

    Cheers!
     
  2. BobK

    BobK

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    I hate to tell you this, but this would be a major project requiring many engineers over a period of years to perfect.
    Why do you think cars have only incorporated anti-collision systems over the last few years?

    Bob
     
  3. Harald Kapp

    Harald Kapp Moderator Moderator

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    Bob, I think this can be done. The number of engineering hours depending on the required accuracy and reliability.

    Is one's own speed really of importance? What if the distant moving object has the same speed? Then there is no risk of collission.
    What matters is the rate of change in distance between yourself and the distant object. Once you have a means of measuring the distance (laser, radar, ultrasound...)
    So what you need to do:
    • set up a distance measurement such that the output of the measurement unit can be read by a microcontroller
    • have the microcontroller update the measurement on a regular basis and compute distance as wel as rate of change of distance.
    • from these parameters you can generate an alarm if
      a) distance is less than a defined minimum
      b) rate of change (approaching) is too high to allow reliable braking (no need for an alarm when the rate of change indicates the other object is withdrawing from you).
     
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  4. Eoghan Ryan

    Eoghan Ryan

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    May 21, 2016
    Yes, ones speed is important because a change in distance alone isn't enough to provide braking guidance.

    The anti collision systems in cars are highly sophisticated because the majority will apply a braking force too and as you can imagine, a system connected to brake application needs to be extremely reliable!

    Harald, I do like your idea of an alarm at a set distance. It is more simple to construct for a start. I can imagine the interface between the GPS and distance measurement is the hard part.
     
  5. davenn

    davenn Moderator

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    specially when domestic GPS has an accuracy of around 10 metres. you will have hit the car and the GPS will be telling you that you are still 10 metres away from collision !

    this is why microwave radio is used in anti-collision systems


    to be blunt, this project is likely to be well outside your current capabilities
    till you become more experienced


    Dave
     
    Last edited: May 22, 2016
    hevans1944 likes this.
  6. Eoghan Ryan

    Eoghan Ryan

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    May 21, 2016
    The GPS would be only used for speed purposes only. How accurate is their speed reading -/+ 10/15kph?

    I believe the laser to be the best option for reading distance.
     
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    When I first read the title I assumed you were seeking help in the final stages of building an electronic companion.

    However I now realise I was wrong.

    The title refers to yourself, but the project is probably bordering on the same complexity :)

    Perhaps you can google ACARS for an already existing version of what you want.

    If you don't want a cooperative system, then you may need to investigate what (say) Google used to identify other moving and stationary objects.
     
    Eoghan Ryan likes this.
  8. hevans1944

    hevans1944 Hop - AC8NS

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    Microwaves are more reliable. The reflection of laser beams from vehicle surfaces is problematical.
     
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  9. Eoghan Ryan

    Eoghan Ryan

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    May 21, 2016
    Do microwaves not need a receiver on the object being measured?
     
  10. davenn

    davenn Moderator

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    no, just a transmitter and receiver on the vehicle doing the distance measuring
     
  11. hevans1944

    hevans1944 Hop - AC8NS

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    Have you never had your automobile speed measured with a "radar gun"? Automobile manufacturers are now experimenting with anit-colliision devices based on the same principle.
     
    Harald Kapp likes this.
  12. Harald Kapp

    Harald Kapp Moderator Moderator

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    GPS doesn't tell you your speed, nor will it tell you the speed of another object.
    GPS gives you your position, speed is calculated from the change in position vs. time. Accuracy of speed therefore is on the same order as accuracy of location.
    This still doesn't help you with the speed of the other object, though.
    As others have noted before, microwaves are much better suited for this part of the project.

    You could use GPS for this part of the project.
     
  13. Eoghan Ryan

    Eoghan Ryan

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    May 21, 2016
    Thanks for the advice.

    I wouldn't need to know the speed of an object, just ones own speed. The objects distance is the critical factor from my position.

    I might consider retro fitting a device to the car itself to measure speed instead of using GPS. It might eliminate a complex interface problem?
     
  14. Eoghan Ryan

    Eoghan Ryan

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    May 21, 2016
    So microwaves operate on the same principle as radar? Or are they pretty much one and the same?
     
  15. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    radar USES microwaves (typically)
     
  16. AnalogKid

    AnalogKid

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    In round numbers, microwaves are radio waves with a wavelength of 1 meter of less, which corresponds to a frequency of 300 MHz or more. A typical frequency for radar guns, microwave ovens, and wireless routers is around 2.4 GHz, with a wavelength of just under 5 inches.

    You need a microwave receiver at the other end only if you are transmitting information. The RA in RADAR stands for radio. There is no explicit requirement to use microwaves for RADAR, but the short wavelength gives good distance resolution.

    ak
     
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  17. BobK

    BobK

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    Just knowing how fast you are approaching an object and the distance to it is not enough.

    Consider a car going around a curve on a road lined by trees. Any prediction based on the instantaneous velocity (not speed) of the car will predict that it will hit a tree at any time! And the trees are not even moving.

    To predict a collision you have to accurately predict that path of the vehicle you are in and the object you are tracking. This is way complicated.


    Bob
     
    Last edited: May 23, 2016
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  18. Eoghan Ryan

    Eoghan Ryan

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    May 21, 2016
    I understand the problem you have put forward. The main field of use will be on motorways (freeways) where the instance of rear end collisions are alot more prevalent. Especially here in Ireland!
    I would also configure the system only to activate above a certain speed. As you would become quite infuriated sitting in town traffic with an alarm buzzing!
     
  19. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

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    It's good to see you starting out your electronics education designing a simple project. I thought you were going to ask something complicated! :D

    Chris
     
    hevans1944 likes this.
  20. Herschel Peeler

    Herschel Peeler

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    Feb 21, 2016
    Did you have a target price in mind for this? Maybe $4,000?
     
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