I am an Arduino beginner, and currently trying to make a pretty challenging project for school.
What I want to do:
Trigger a camera or flash inside a moving car according to certain points along the road.
If you look at the attached sketch,
I want to generate somekind of trigger exactly when the car drives past point A, and then past point B.
I though of several directions to solve this:
GPS tracking, some kind of sensor on the road, or calculating the timings according to the car's speed.
Some notes:
the system has to be 100% precise.
ideally it would automatically adapt to any speed the car drives at.
I might need to scale things up to many trigger points,
so the best way would be as cheap as possible (namely, expensive sensors might be problematic).
I have no proplem working hard and I learn fast,
but I would be happy to hear your oppinion as to which direction I should focus my energies on.
the system should be as precise as possible without getting to expensive.
I can't really say wether I want the triggers active or passive because I don't have experience with this,
but I would say - what would be the realistic way for a beginner to do this?
ideally it would automatically adapt to any speed the car drives at.
How can it not be if you are detecting when the car is at a fixed point.
by this I meant to simply have the camera shooting at constant time intervals and driving at a constant speed,
(this would obviously result in a huge error margin).
the system should be as precise as possible without getting to expensive
You need to start hanging firm figures on these terms; it's just too vague.
Yes I guess you're right, just hard for me to say without starting working on the project.
would it be possible to say in the most broad lines what would be a logical way to attempt this?
like, what should be the first thing I should try and acheive/figure-out?
Go with GPS - confirm first that it's able to get a fix in the vehicle. Then just start taking picutures as you approach the waypoint and continue until a little after you pass it.
I would imagine you want to use GPS and motion sensors to figure out when to fire the camera.
The triggertrap IOS/Android apps do this with their phone's builtin GPR/motion sensor on the DistanceLap function. Unfortunately, I don't know what kind of programming was involved, but you might want to check out the documentation for appropriate settings to think of: https://dl.dropboxusercontent.com/u/12309545/TT%20Manual/Triggertrap%20Mobile%20Manual.pdf
I recommend that you paint bar codes on the road in white paint. Then shine a light out the bottom of your car, and pick up the reflection with a photo diode.
vertigo5:
Trigger a camera or flash inside a moving car according to certain points along the road.
Depending on circumstances, triggering a flash inside the car may introduce safety issues if you risk dazzling the driver, or other car drivers in the area, or distracting somebody at a critical time.
As others have said, you need to nail down your accuracy requirements: how much variation in the position would it take for your solution to be unusable? 1cm? 1m? 10m? 100m?
How are the positions defined? In particular, are you able to use any sort of beacon to indicate the position?
PeterH:
As others have said, you need to nail down your accuracy requirements: how much variation in the position would it take for your solution to be unusable? 1cm? 1m? 10m? 100m?
How are the positions defined? In particular, are you able to use any sort of beacon to indicate the position?
I would say probably 5-10m would make it unusable.
What do you mean by using a beacon to indicate position?
Would that be for example somekind of flashlight at each point?
TanHadron:
I recommend that you paint bar codes on the road in white paint. Then shine a light out the bottom of your car, and pick up the reflection with a photo diode.
I would say probably 5-10m would make it unusable.
Do some simple arithmetic.
At 100kph (62mph), your vehicle is doing 28ms-1.
At that sort of speed, simple shutter lag (you still haven't said what sort of camera you're using) could give an error of 5m.
Almost certainly, a standard 1Hz GPS update rate alone is going to be unusable.
