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Sharps, Sonar and a dead horse...

This is a dead horse, but...

Again, I am still sick of my sharp sensors. I am looking at  the LV-Max-Sonar(s) EZ(x) sensors as an upgrade... These are the "single-eye" sorta sonar sensors.

Open Question:

Has anyone played with these? Plus and minus for the output options (serial, an., pulse)? Is there clean data?  Etc. Etc.

Gimmie what you got.

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I found that the sharp IS sensor is more accurate - however that may be due to my running them off the same power pin with no filtering, as well as the lin. vs log. differences in the output.

 

check http://letsmakerobots.com/node/11215 for more information, and pictures!

Looking at your other thread and results, it's not so much that the sharp is more accurate, it's that it has a narrow beam of detection. The sonar has a wide beam, you can't just project the reading directly forward, the typical usage would be to use multiple readings together with an occupancy grid to model the environment. Single sonar readings can't be used for a mapping (hence why your sonar map is so  blotchy, it's picking up the walls).

-Fergs

The Sharps have been fine sensors too, no real problems in their use. It might be good to use a little math to straighten out the curve of voltage vs range, but the Sharps have done what their datasheet says essentially. 

Application might be to use sonars as a longer range area detector, with Sharps being used for shorter range point searching in areas your robot needs to pay attention to.

Range is definitely a difference, but I think the width of the detection beam is the biggest one. For instance, try following a wall with a sonar sensor, it's a lot harder than using an IR ranger, since you can't get an accurate read on how far away the wall is with the sonar. On the other hand, try avoiding a chair leg, if you aren't dead on, the IR misses it, but a sonar will typically pick it up.

-Fergs

Used 'em, like 'em, bought some more of 'em.

 I had a "better experience" with these than other sonars. Have a couple original EZ1s, and several more LV-EZ1s now. I usually use the analog output, but have used the PWM output too. The serial I'd heard was a littel inverted, but haven't worked with it. Heard some had problems with noise, but Maxbotix offers a solution. These have been very good at picking out obstacles and giving accurate info. Other devices I've used have been Polaroid sonars, Senscomp Mini-S, and the Devantech SRF04 and SRF05.

I'm not such a fan of the EZ-1s... even with the power filter I couldn't get them to be accurate enough for mapping (I reverted to using SRF-05 sensors and am happy with the results, but I think that's more of a single/double transducer thing than anything else). Actually, robotologist bought up my EZ-1s when I was getting rid of them, so I'm happy he's liked them.

I do like the EZ-3 for small robots navigating in close corridors (such as Trinity Fire Fighting). The narrow beam is something nobody else out there has. As long as you are going for a YES/NO there is something closer than X inches, they work great.

Regardless, I think it's important to use more than one type of sensor on bots. Sonar has a wide beam, IR is very narrow. Neither alone makes you (or your bot) entirely happy. A combination of sensors really is needed for robust navigation.

-Fergs

I have tested one with my "LoMoR" rig and i have to say i am not impressed - (for long range super) - however short range kicks up more echos .

The data is easy to extract - (however i use arduino) - either by analoge-pwm-rawdata.

As a scanning sensor it has a quick response - ie (-: its faster than my servo can move :-)

(the two transducer sonar types seem to be better ie not Lv sonar range).

I am trying to post the results shortly ....... i will see what i can to do to give you a better idea.

 All i recommend with them is to think as "Long range"

At moment i recommend only sharps if you want accuracy - the long range ones are also pretty good.

 

NB:- i will post the LV sonar results on loMoR as soon as i have video cut

Just added video of ........

LoMoR with Maxbotix LV-EZ1 - Ultrasonic Long Range Sonar

....... in action.

These are the best ultrasonic sensors I know of. They have serial, analog and PWM outputs. Having said that, as Gareth demonstrated both IR and Ultrasonic sensors can generate false signals due to things like reflection.

 

Note: you can still destroy them by conecting the power the wrong way around :p

Would you say they are more precise than the more commonly used SRF05 or PING?