I'm new to the forum and had a question. I'm having trouble locating some "waterproof" sensors. I know the HC-SR04 seems to be very popular. Although, for my bot I would like to use it outside. Has anyone had luck sourcing cheap sensors? I've come across using parking sensors but their range is not good enough. Id like my bot to stop within 10cm or so. I'll be using this for obstacle avoidance.
Also, would it be possible to utilize the HC-SR04 and essentially put a plastic cover infront of it to protect it from the elements? Not sure if that'd effect the signal. Or what mateial I could use.
Parking sensors have a much greater range than 10cm - if you get to within 10-cm parking, it's time to brake, quick. I would have thought they would be ideal - built for outside use and bad electrics.
Industrial ultrasonic sensors have ranges up to 5-m and are widely used in harsh enviroments, and have weatherproof sensing faces. They are widely used to measure the levels in tanks - they never face upwards into the weather.
Anything in front of it is going to affect the range - a thin membrane might work, like thin polythene - you have to experiment. I'm no expert, but I would think that a protective surface some distance from the sensor might be worse than something really close - the membane almost has to vibrate with the sensor, or be transparent to high frequency sound waves - try looking up acoustic properties of different materials.
I have used ultrasonics in bad environments by attaching a tube or horn in front of them to stop vertical rain.
Yes, you can get cheap sets of after-market reversing sensors on eBay I believe, which are sealed.
But the drive electronics could be a problem unless you hack into the control board that comes with them.