Let's Make Robots!

I'm getting sick of Sharps --Is there something better?

Alright, this is it... I am anti-sharp distance sensor. I spent over a week fighting noise on the power side which screwed with my RF reciever. I have fried them because thier pin-out does not match the configuration of a servo connector or the picaxe 28x board. Thier numbers jump all over the place. Now it seems that all four of the ones I have are "worn-out". By that I mean this:

I added a .1uf cap to deal with noise and now it seems they won't output anything without the cap attached. My picaxe will not sync while even just one sensor is plugged in. On top of that, all of them are spitting out a measurement of 50 or so when looking at infinity and the total sensing distance is down to about 10 or 12 inches maybe less. I am sick of dealing with these silly things and do not want to spend more money replacing the ones I have.

The Problem:

I have to have a minimum of 3 sensors on Walter to deal with his width. A SRF05 centered on a servo is a given thus leaving the needed sensors to catch the corners and sides. I have looked at other sonar systems (the ones with just the single black emitter (SRF02?) and even thought about just spending the bucks on 2 more SRF05's. The issue is (especially with the "single emitter" (which fire constantly)) is interference from sensor to sensor. In many instances I will have 2 sensors firing almost directly forward and the ultrasound from one will screw with the readings of the others. (All 3 sensors must be able to turn via servo). I have looked into some of our fellow LMR'ers IR distance systems but I just can't seem to get the distance I need.

What the hell can I do here?!?! Does anyone know of an upgraded Sharp? Is there a quality IR distance sensor out there? Something? Maybe a 180 degree sensor that does not have to be swept with a servo? 

Oh, and I don't have a lot of cash. 

For the love of God, help.


Just had a thought:

Has anyone tried any of the home made IR distance sensors with a lens or two to increase distance/ sensitivity? --Maybe I should experiment a bit...

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.
I've heard about the polaroid...only thing is I could never get myself to canibalize a camera...as a photographer, destroying a camera is  sacrilege.....
I would go with the maxbotics sonars. Take a look at this pdf about chaining several together Chris. Wire each one to an ADC for readings, plus have a digital pin to tell them when to start. They take turns pinging the distance so you dont have to worry about crosstalk.

I have a op amp chip, maybe i could try that.

btw: (By The Way, yes its nerd talk) did you connect all your other analog pins to V1? helps a ton 

You tie unused pins to GROUND, not to V1.


If you go to sonar, why not check out the line of maxbotics sensors...they've looked interesting andd somewhat cheaper that the srf series...

It seems there are 850nm LED's and 950nm LED's and the 950nm wavelength (seems to be more standard for emitter/detector pairs) is quite limited in terms of output. Now, on the other hand, in terms of the 850nm wavelength, you can get up to 5w! These are used for nightvision systems. Now, I checked digikey for 850nm phototransistors and they do make them but I simply had too many options (you guys know how digikey is) when trying to find a specific unit to buy.

Does anyone have any thoughts on these 850nm wavelength emitters and detectors?

Could anyone suggest a good phototransistor to use at this wavelength?

This is as far as I got with Digikey:



Although you can get very powerful IR emitters they can be dangerous to the naked eye. Considering My TV remote can work over 6M (about 20 feet) power isn't your problem. It is better detection that is required.

In making my IR object detection sensors I found that daylight blinded them and even inside with all the doors and curtains closed the IR that did get through reduced the reliable range. I did get over a meter range but not with the reliability you want.

Ultrasound is probably the best and most reliable way. At this point I have been working on a homemade sonar that is cheaper than the bought units but might only have about 2M range (6 feet). Unfortunately it is still in the developement stages.


I agree mint, but really -A whole meter? I would say most of the robots on this site start reacting/ turning in the 1' range (what is a meter... 100cm or 1000cm? --1 foot is a third of that 33cm or 333cm).

To the point --I agree, it should be a contest/ chalange/ project. Someone here should be able to get it done.

I am thinking lenses, focus and a good amp on the receiver.

How high is walter? about 40cm? 1.2 feet? if its head is 40cm off the floor and it can only see 33cm, what could would that do?

anyway. Your setup with the beacons have pretty good range. What if you take one of those beacons with a nice powerfull LED from a remote on top of walter and focus the light with a lens? you should be able to get at least 2 feet range.

The receiver unit from picaxe (i asume you use that one) has some nice specs (amplifier, de-modulater etc.) all the nice things you want except for the wide angle.

Actually all the distance sensors are under the chassis -there is nothing in the head.

I was thinking about the 30khz 3-pin receivers but they are a little too good- But I'm open to any thoughts using them.