Ultrasonics: Will it work and how to make it work

Technical Electrical
1

My question is in regards to ultrasonics. This is the ultrasonic sensor my team was thinking of purchasing:

http://www.sparkfun.com/commerce/product_info.php?products_id=8502

  1. Will this work with the control system?

  2. If so what how would I wire it? I’m figuring connect to PWM and plug into Analog breakout.

  3. What kind of connections do ultrasonics typically have (Power, ground, signal etc…)

  4. What do you think of this model and brand. Do you know any better types?

    Thank you for any help you can provide.

    DavidB

2
  1. It should work. There is a built-in class in WPILib to control and ultrasonic sensor.
  2. I believe that would work.

I don’t know much about 3 or 4 (we last worked with them in 2007). All I can say is that they were the most reliable sensors we worked with.

3

I have worked with ultrasonic range finders in some of my projects back in the day. The fun thing with them is the sound pulse they emit is conical (radiates in a cone shape from the speaker element) and it can generate a feedback wave from the ground. Also, they like the target to be a solid object. If you are looking to target the trailers, you might have a problem because they are mostly air.

Here are some things to look out for:

  1. Draw the cone in a 3D CAD model and make sure nothing is inside the cone before your intended target.
  2. The sensor has a minimum effective distance (somewhere between 4"-6" usually - this should be on the spec sheet) so make sure your target never gets closer than the minimum distance.
  3. Ignore values higher than some optimum distance. Eg: If you intend to start acquiring your target at 20", ignore values greater than 25" because they could be junk reflections from objects other than your target.