This is for my wife. She deserves a tech gift for putting up with all my wires and tools lately!
I made a car rear obstacle sensor with audio alert. You can see how far something is behind your car when backing or parallel parking on LCD, both analog bar graph and digital readout. Plus it beeps like a Geiger Muller sensor when it comes closer and closer to an obstacle. I've tested it with a 12 ft phone cord. It's good to go on my car for a field test!
I've made two versions of the code, a nutshell version which turns on and does what I said it does, then the fully interactive version with all the menus and adjustable parameters so if you want earlier audio warnings or want it off, choose from parameter list and customize it! This hopefully helps beginners (nutshell) and advanced users (full)! Leave some feedback!
Update: it's warm today (by our local standard) so I got out and installed the sensor with my wife. It worked!
12FT 4-wire phone cord, about 10 pieces of wide tape and some masking tape later, the sensor is on my rear bumper sticker. I had it on my trunk first but it is angled and too high. It couldn't detect a car but a garage door was fine. So I moved it to the middle of the rear bumper cover.
Thanks! Forgot to mention I got some 3M "velcro" stickers with adhesive backing. Will plan for next weekend. Too much exams to grade. With cold weathers like in my area, you gotta be able to remove these sensors at night. I don't have a garage, although with my arduino spending I could rent 2-3 garages You just have to stick to what's more important!
Cool. Now work on that sound, it should be a nice soothing low frequency gentle gong gong gong, picking up tempo. Yours sounds worst then my wife's shrill warnings for me not to back up to close to something.
You mean increasing pitch as the obstacles get closer? Just several more variables I can put in my parameter menu! I have length of beep, length of silence, audio alert on/off in there already.Now I can add pitch, pitch ramp rate, and ramp pitch on/off. It's rather nice to have a parameter menu so I didn't have to re-upload if I don't like the way the pitch ramps.
BTW, that black box was made from a $1 3X5 card holder. It was black plastic sheets. I tore it down to make a face plate for my other project:
This picture was taken with a black paper face plate before I made the plastic one.
I just used a blade to cut on one side not so deep and fold at the cut. Then I spent a few minutes with my hot melt glue gun. There were also three sheets of cardboard behind the sensor to hold it in place.
I think that I am going to copy this project a bit, I already have an arduino in my trunk connected to ignition, and a nice monitor in the front (for alternative clock and temperature sensors):
adding a ping or something would be interesting!
Fede
Alright! I suggest you got get two sonic rangers. Since I've installed my sensor, I've grown an additional sense: every time I drive, I look at the rear bumper covers of the cars in front of me. I've seen cars with 2 or 4 sensors spread around the bumper evenly. I think you will want wide angular response as well but mine was narrow so it measures more or less things directly in front of it and not so much for things on its side. Having at least two will be much better than one. You can use your display to show two bars, one for distance to obstacle on each side.
I'd like to do some test, I have here 2 types of sonic sensor... A parallax ping and a cheaper i2c SRF02. Probably I will wait for warmer days, as here in Italy for our standars it's still cold I like your project a lot!
Ok, then on to your next auto project. How about a arduino low tire pressure alarm? My 11 year old Buick has one built in, tells me to check tire pressure.
retrolefty:
Ok, then on to your next auto project. How about a arduino low tire pressure alarm? My 11 year old Buick has one built in, tells me to check tire pressure.
Lefty
I'd like that too! I don't have a pressure gauge. The cheap ones all fell apart on me. How do you sense pressure? I know pressure capsules with voltage output but how do you do that on a rotating part? Now i have an idea. Put my persistence of vision display on my wheel so the dude driving next to me can honk me if he sees the message: "This dude needs more air on this tire!" XD
mmcp42: I can certainly do that. It won't help me backing blindfolded though!
I'd like that too! I don't have a pressure gauge. The cheap ones all fell apart on me. How do you sense pressure? I know pressure capsules with voltage output but how do you do that on a rotating part? Now i have an idea. Put my persistence of vision display on my wheel so the dude driving next to me can honk me if he sees the message: "This dude needs more air on this tire!"
This will be fun. I will only give you hints and additional hints if asked. The Buick has NO pressure sensors used to determine the low pressure warning. Also it does not tell me which tire is low, just that one needs attention. So how might you think it can determine that?
I'm guessing:
a) level sensor, if one side is low chances are the tyre (sp) is flat
b) rpm sensor, if one wheel is going "faster" it's got a smaller (effective) diameter, so the tyre is flat
a) is very hard to measure accurately
b) has to take cornering into account
Since you challenged me to figure this out, I'll have to ask:
if you deflate all tires equally from equally well pressurized initial condition, will your old Buick still tell you low pressure?
if you deflate just the front tires but equally, with you get a low pressure warning?
if you park your tire-well-pressured old Buick on a slope (Should be plenty in SF, right?), with its side doors facing the top of the slope, will you get low pressure warning?
if for some reason you're driving your old Buick and it reports to you tire pressure is low, will stopping the car turn off the warning?
I'm thinking about a bubble level (or tilt sensor) running under the car from left to right but if you carry out the above thought experiment and get back to me, I can be more or less certain about my guess.
You just have to stick to what's more important! 
