Question about PING.

MovieMaker

Here's one for you guys.

I am thinking about building a robot that would be apprx 3 feet tall. If I used PING to scan as normal, I am sure the would only see a portion of what he was pointed to. What are my options? About how wide is the scan, let's say if I have it 3' up in the air. Would I need more than one PING, or should I have it where it would swivle up and down and left to right?

I just wanted to get your ideas before I start.· I have also seen people put a bunch of sharp IR units in the place of the PING. Would this be another option and which would be best?

·

Timmoore

You need to have a better idea of the probelm. How fast you are moving, what you are trying to detect (size, etc), what range (depends on your fast)
ping detects to about 3m, there are other ultrasonic that detects to 6m (maxbotix.com and devantech (http://acroname.com/robotics/info/articles/devantech/srf.html)
Shapr do many ir sensors and they tend detects to around 1m, though there some that detect to 3m. http://www.junun.org/MarkIII/Store.jsp sell a good range of the sharp detectors.
Then you need to know how quickly you need to detect (again how fast are you moving). You may not be able to move a sensor in a scan that fast. If you use multiple ultrasonic you normally can't have them all detecting at the same time (see http://www.maxbotix.com/MaxSonar-EZ1__FAQ.html#How_can_I_use_more_than_one_MaxSonar_EZ1_in_the_same_system for a decription of hte problem).
I have't had a problem with multiple ir.
Will you have multple objects to detect? there are some sensors that detection multiples srf02 for example and the sharp multi-beam sensors but most just give you the closest.

MovieMaker

It is going to operate the SAME as the boebot, only 3' instead of 7 or 8".

I am really not looking for the DISTANCE as much as it seeing something it is going to bump into. The way I have it now, it works fine with both the IR and the PING. But raising the Ping unit up another 2.5' could make it miss things directly in front·and below it. I am just looking for a simple answer if there is one.

Thanks for your reply.

:-)

Post Edited (MovieMaker) : 7/11/2009 10:46:15 PM GMT

Timmoore

If you have a boe-bot I would run a few experments
1. lift it to 3' and see if the ping can detect, stuff on the ground at a range that the bot will stop before hitting it, if yes your good
2. If not put the ping on a servo that goes side to side and see i you have problems with the bot going faster than you can sweep the ping, i.e. hit something before detect it.
if no then you can put the ping on a servo and sweep the ping up and down
3. If yes then you need more than 1 sensor
the simple choices are 2 pings at different heights and dont ping them at the same time, or 1 ping and 1 ir

MovieMaker

Thanks, Tim.