They work differently. They figure the distance by the angle at which the light comes back to the reciever. That only provides distance.blueroomelectronics said:Wouldn't it be easier to use a Sharp IR distance sensor?
mneary said:Unless you're using 40 KHz filtered sensors, why are you modulating the LED at 40 KHz? If it's just to save power, remember you only need to light up the LED when you want to take a reading.
Torben said:What about using two of them and comparing the distances returned? That should give both the distance and the angle, assuming the resolution is good enough.
I don't know how that compares in terms of final part count and cost, though.
Torben
mneary said:When the bot is crooked, you might not get what you expect. The cones of the detectors will point in the same direction as the emitter. Draw some pictures and you'll see what I mean.
Pommie said:Have you considered the cones of the receivers as suggested by mneary, if you think of the receiving diodes as emitters then the overlap of the cones produced will stay the same no matter what angle the wall is.
Mike.
while(1){
both led's off
catch "sense" from all 6 receivers
led1 on, led2 off
catch "sense" from all 6 receivers
led1 on, led2 on
catch "sense" from all 6 receivers
led1 off, led2 on
catch "sense" from all 6 receivers
compare state of all 6 receivers in all 4 stages (00/01/10/11)
output decision
}
What sensitivity/(distance resolution) did you get? What is the shortest distance you could measure?Then I tried something completely different, one IR LED, and one IR Receiver, 1K resistor in series with the LED and variable resistor 0-100K also in series with LED. Reading values from the Receiver with different "positions" of the variable resistor determines the "distance"... It works
Light is too fast. ~300Mm/s so if we say that you will use cheep dedicated pic for the sensor, those usually run on 4MHz hence 1 instruction takes 1us .. and in 1us light will travel 30000m .. so any measurement of length using light is impossible without high speed mcu.3v0 said:Why do you prefer US or IR? I have never used the US.
It can work, the biggest problem is "different reflective index of surrounding objects". An generale, you can test yourself, just build a simple detection circuit and manually change the resistor value .. as I already wrote .. the major PITA with light is3v0 said:I need to do the variable resistor bit you were playing with but have not yet made any provisions for it on the board. I figured I would get the basic detection working first and then experiment to see if I could get the variable power to the IR LED working for range detection.
3v0 said:What sensitivity/(distance resolution) did you get? What is the shortest distance you could measure?
3v0 said:After hearing the same think from you and Bill I went back and check again. The sharp IR distance sensors do not seem to function at distances short enough to be useful.
I did find a non-analog sensor that goes active at 5 cm. Digikey has them GP2Y0D805Z0F for $3.25 each. One could use them as electronic wiskers with one on each side of the robot. If one did a slight S path so that the sensor toggled frequently it could work. It may be hard to aquire the wall to start with.
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