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Topic: ‏how to make robotic arm follow led ?????? (Read 297 times) previous topic - next topic

tomer8969

does anybody have any idea how to make my robot arm following LED light???
I need to make my robot arm fully automatically another robot with an LED in the end?
which kind of a sense of should I use? and what is the best method for this kind of application?

thanks a lot :)  :)  :)

MorganS

First you need the robot to be able to detect the correct LED and not get fixated on some other bright light. If you have a controlled environment then you can choose a color for the LED which doesn't exist in the environment. Remember infrared is a color.

If you can't control the background colors then the LED must flash with a distinct sequence which the robot can detect. Think of a TV remote - the TV only responds to its own remote and not any other. The Arduino can easily send and receive TV remote type signals so it's not difficult to do this part.
"The problem is in the code you didn't post."

wvmarle

Definitely go for a modulated signal. You can even use white or any visible colour for this as you can easily let it flash fast enough to have it appear constantly on for your eyes, while the Arduino still has no problem to detect it. That's by far the most reliable way of finding your target.

Secondly you have to find a way to determine where the light is.

You could go GPS style, triangulating it based on the time difference at which the signal appears at a number of sensors. Four such sensors in a 3D pattern and you can calculate in which direction the source is, assuming they all can see the source. If one can not see the source, that's another clue on the direction. Note that the timing required is of course out of scope of the Arduino. You'll need specific hardware for this.

Another option is going radar style: have a sensor scan the surroundings, and by restricting its field of vision you can find the direction of the light source. Just scan until you see the LED. This is definitely in scope of Arduino type microcontrollers.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

tomer8969

Yes but now that I understand how to detect the LED how do I make the robt atm follwo it??

wvmarle

Make it move in the direction you last sensed the LED... remember to check the direction of the LED frequently.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

falexandru

You may need two or more light sensors.

Light is one thing while color is something else.

The light sensors that I know are un-believelable sensitive to light, so they modify consistently and rapidly, leaving your LED light not perceived from this noise.

But in a sense you may use this sensitivity to reach your goal. So, the code will have to detect high changes in the intensity of light.

Then, if you have a pair of sensors, they will detect the changes in one plane. Another pair will detect the changes in the other plane.

This - if you go for a cartesian detection (XYZ). But if you go for an angle positioning, that is a different story, and perhaps more laborious in terms of calculus. Check robotics.

++++

From my experience, the color sensors are of mixed efficiency, so it may be the case to check the particular one you have.

That is if you go for budget items.

An alternative may be to use the line-follower robots strategy while wearing a white glow with a black strip.

++++

I suggest starting by detecting one-plane move XY.
You may add Z (height) at a later stage. Or decide for a different positioning system.


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