Author Topic: EZ1 Sonar problems outside  (Read 644 times)

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Offline AsellithTopic starter

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EZ1 Sonar problems outside
« on: September 22, 2012, 10:33:46 PM »
Ok I've been out of the robot scene for a bit and our new makerspace in Pensacola ECCMakers.com has pulled me back in. I don't have much time to work on stuff any more after starting my own company but I did do more work on an old project to showcase at a makerspace event today.

Here is a video of the bot working just fine in my house.



It even worked in the space this morning.

The event was a sustainable concert that (with some makerspace help) built a solar and pedal powered PA system and had an all day concert and the PA system was off the grid the entire time.

We had a booth for showing off projects and I tried to get my bot to work in the parking lot.

I have 3 continuous rotation servos with Omni-Wheels, An Axon II, and 3 EZ1 Sonar sensors.

I didn't have time for full blown Omni-Movement so I compromised with just backing away from anything when a sensor read 25cm or less. Rotates for 0.5 secs if two sensors trip.

Works as planned inside but I take it outside and it just rotates. So the only explanation I can come up with is something is screwing with my sensors and they are tripping early.

It is really close to the ground so I put some spacers on the sensors and tried to get it off the ground more. It still just spins.

The parking lot was a bit rough but I found a small and level concrete slab. Still rotates.

So any ideas on what might have been screwing with my sensors?
Jonathan Bowen
CorSec Engineering
www.corseceng.com

Offline sufendi

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Re: EZ1 Sonar problems outside
« Reply #1 on: September 24, 2012, 08:32:50 AM »
i think you need to read the sensor datasheet first. in normal situation an ultrasonic sensor will not send back his measured distance if the distance is too far ( max<5m  for normal ultrasonic sensor).
i hope my answer will help you.

Offline AsellithTopic starter

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Re: EZ1 Sonar problems outside
« Reply #2 on: September 24, 2012, 11:04:18 AM »
I'm using the analog output. So if anything the sensors should just read max range not 0 VDC. I don't see anything on the datasheet that would explain what the sensor does to the analog output if it doesn't get a bounce back. The PWM just holds high if no target is found. I'd guess that when it updates the analog output that it just sets it to max.
Jonathan Bowen
CorSec Engineering
www.corseceng.com

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Re: EZ1 Sonar problems outside
« Reply #3 on: November 11, 2012, 08:23:18 AM »
I'd try bending the brackets holding your sonar to aim the sonar slightly upwards.

The ground is probably within the detected cone after a few feet of range (which it isn't inside because the walls are so close).

 


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