Flash Bob : SpeedCamera

speedcam14M_02.bas (2391Bytes)

I our neighbourhood there is a place run by volunteers where kids can ride around on skelters, tricylces and bicycles. The city donated some traffic signs and traffic lights and I thought it would be fun to build a working speed camera for them. 



using a picaxe 14M I had lying around, an SRF05 ultrasonic ranger and the guts of a cheap disposable camera, I build a small box that meaures the speed of an object moving away from it. Because I don't know the first thing about how to use a flash, the picaxe simply flips a relayswitch that I wired to the flash button of the camera.


I also wired a switch to the charger and a push button to the flash, so you can manually set of the flash or test the speed without actually flashing. 

Three LEDs indicate the status. When it is starting up, the picaxe lights up the green LED. Then it starts to measure the distance until three consecutive identical distances have been read, that will be used as the maximum range. When a max range has been found, the red LED lights up for a second and the device is ready.


Any object detected further than 50cm away and more than 10cm closer than the max range is considered in range. When three ranges have been taken that more or less indicate a consistent speed, the speed is calculated with the first and the last range. 

When a successful speed has been detected, the yellow light goes on and when that speed is higher than the set maximum, the red light goes on and the flash is activated.

I have only tested this by walking past it with a low speed set and by moving away from a wall, and that seems to work. i hope to test it in the field next week. no idea how accurate this is, but that is not very important.

Since this is a cube with a ultrasonic ranger, I felt obliged to call it Flash Bob ....


Great Idea

Hi mintvelt.

What a great project!  I rather like practical things and this also will give kids a lot of fun trying to break the speed limit :-).  I particularly like the dial on the back of the enclosure although I think you need to mount it next to a whiteboard that can be used to create a leader-board !


Thanks guys.
I like the

Thanks guys.
I like the leader board idea. I still have to attach the serial jack for testing and debugging. Using the serial cable I can use my laptop to register the speeds.
Hopefully there is enough program space left in the picaxe to do that :slight_smile: