Ping Ultrasonic Sensor wind interference - please help!!!
rubberband_freak
Posts: 8
I have recently purchased 2 Ping))) ultrasonic sensors. I'm working on a semester long project that would use these sensors and an Arduino UNO rev 3 board to measure distance between my car and another object while parking my car.
I'm also hopeful to use this sensor to measure distance between my car and another car while driving. The problem I've run into is wind and noise interference. I blew air using a motorized fan into the scope of the sensor (without sensing the fan itself) and it threw the reading off (found an "object" 20-30 inches closer). I also found that noise threw it off a little bit too.
If using this sensor for just parking, wind or noise are not a huge concern. Wind speeds while driving would obviously interfere. I'd really like to use this while driving to detect cars in front and behind me. To the best of my knowledge, some newer cars use ultrasonic sensors for this purpose, but I've yet to find how they've corrected for interference.
I've looked into the new laser sensor that was just released by Parallax, but it does not get the range I need (and costs more $$$). I'm also using the parabolic reflector stand from gadget gangster http://www.gadgetgangster.com/find-a-project/56?projectnum=361. I've run my tests with and without the reflector and got the same, disheartening result.
Other than somehow correcting for interference of wind at different speeds in the program code, does anybody have any suggestions to rig up some sort of wind/noise guard that would not interfere with the sensor? Sorry for the long post, I wanted to make sure I covered everything.
Thanks ahead of time for any and all suggestions!
I'm also hopeful to use this sensor to measure distance between my car and another car while driving. The problem I've run into is wind and noise interference. I blew air using a motorized fan into the scope of the sensor (without sensing the fan itself) and it threw the reading off (found an "object" 20-30 inches closer). I also found that noise threw it off a little bit too.
If using this sensor for just parking, wind or noise are not a huge concern. Wind speeds while driving would obviously interfere. I'd really like to use this while driving to detect cars in front and behind me. To the best of my knowledge, some newer cars use ultrasonic sensors for this purpose, but I've yet to find how they've corrected for interference.
I've looked into the new laser sensor that was just released by Parallax, but it does not get the range I need (and costs more $$$). I'm also using the parabolic reflector stand from gadget gangster http://www.gadgetgangster.com/find-a-project/56?projectnum=361. I've run my tests with and without the reflector and got the same, disheartening result.
Other than somehow correcting for interference of wind at different speeds in the program code, does anybody have any suggestions to rig up some sort of wind/noise guard that would not interfere with the sensor? Sorry for the long post, I wanted to make sure I covered everything.
Thanks ahead of time for any and all suggestions!
Comments
Welcome to the forum!
Perhaps there is something in this thread that will help: http://forums.parallax.com/showthread.php?133544
-Phil
That sounds like something to try, but if the wind is constantly blowing into the sensor, it would give a constant incorrect reading rather than spike up and down.
-Phil
-Phil
-Phil
You might look at McMaster. They can usually ship the same day you order and sometimes get it to you the next day, but it's always more expensive than if you find it somewhere else.
On McMaster, just search rubber foam, then look for foam structure and select open cell.
http://www.mcmaster.com/#foam-rubber/=gh2juo
I had some old over the ear, ear buds, that had little removable foam coverings, they fit over the transducers just right,
I placed my Ping into a shallow Tupperware container with only the transducers poking out.
drill 5/8" holes for the transducers, and push hard to make a nice seal, add silicon around the cable.
and your good to go for the car wash, or rain storm...
I think I have been lucky, as I have the Ping tilted slightly toward the ground, so no water collects in the transducers.
-Tommy
Seems like an interesting design, but I'm a little confused. Would you happen to have a picture or diagram?
See if this picture clears up some of my babble...
I took off the little ear bud caps for clarity.
as you can see, press fitting the transducer's into slightly undersize holes makes for a nice seal..
-Tommy
Thanks for the reply! I now understand what you were talking about. I might give your design a whirl to protect the sensor from the elements. I'm going to need to experiment with various types of earbud/microphone foams to see which works best to cancel wind noise, but does not interfere with readings. Thanks Tommy, Phil, and ElectricAye for your responses and input. I'll try to keep you guys posted.
The maximum range of the Ping is 3 meters, or LESS THAN one car length. The only safe speed at which to measure that length would be the kind when you're in the McDonald's drive-thru lane. And in that case, wind isn't going to be a problem. If you're traveling at 30 MPH, and you're within 10 feet of the car in front of you, you will not have time to stop your car if given a warning. Better hope your airbags are in good working condition!
Ignoring the environmental issues like water and bugs, wind interference just doesn't come up at the speeds and distances over which the Ping would be a useful (and safe!) sensor. Remember that if you do find a wind sock material that cuts down on the wind, it'll also cut down the maximum range. It's impossible to block wind without also attenuating the sound waves to some degree.
Car makers may use ultrasonic sensors for backup sensors, but any forward-facing sensor is going to be either radar, some kind of proximity detector (e.g. LIDAR), or some such. None of these are possible in a $30 sensor.
-- Gordon
Good catch! I got as far as "parking" in his original post and assumed the wind thing was for parking in very windy conditions. (Where I live, that would be a valid consideration.)
-Phil
I figured it did no harm to learn about the ping first, and then learn all about Radar and such.
A little caveat about the ping shown in the photo,..it's under the porch, and not under the hood/bonnet of an automobile.
I have water blasted near and around the TupperWare/Ping box, and it still indicates when something
walks or blows across its path. after two or so years...
The PING((( rocks!, :thumb:...just not under the hood of an automobile...
-Tommy
http://en.wikipedia.org/wiki/Collision_avoidance_system
and
http://en.wikipedia.org/wiki/Precrash_system
Other sensor types have significant problems, including short range, greatly reduced accuracy in bad weather, exposure to elements, effects on other drivers, and so on.
Most current systems provide a backup to existing safety measures. They can't warn early enough for humans to react, so instead they do things like "pre-trigger" the airbags, so they are more sensitive in the event of an actual collision.
That said, there's an emerging science in using vision technology for this sort of thing, backing up radar for foggy conditions. A stereo dash camera analyzes the scene ahead, judging distances the same way our eyes do. Outlines of cars are mapped as they come into and out of view. A vision system is more useful at higher speeds, which unless the driver is bonehead stupid will never be the case in foggy or poor weather conditions. (Actually, the camera could be used to tell the driver to slow down ... "You can't see ahead of you, dummy!")
-- Gordon
I have the algorythm that must be programmed if anyone is interested.