How to make my robot follow me?

[verdelet]

Im trying to build a simple 4 wheeled robot using the Arduino microcontroller & a sonar sensor.

My goal is to make this robot simply follow beside me everywhere I go, or be able to make it follow sum1 else.

From what I make, I can only detect distance between the nearest object and all that jazz, but how do I actually make it follow me?

I am an absolute beginner to electronics & robotics, with some programming background.

Exactly how would I approach this?

Thanks.

[Joker94]

Well a sharp infared sensor should be able to detect the person and follow them, the only thing i am unsure of is whether you would be able to use 1 mounted on a servo or you might have to use two or three to keep track of a person.

You should be able to mount them onto the $50 robot board and program it to do what you want it to acomplish, if you want to run it off some more advanced code since you have programing back round it may be a good idea to go with the Atmega 168 adaptation of the $50 board

And i know some one has posted something about robot following using infared but i could not find it.

[Joker94]

here is a previous post on the same topic

http://www.societyofrobots.com/robotforum/index.php?topic=1046.0

[radhoo]

I'm not sure your ultrasonic sensor is enough for that.

I mean you could do a simple approach like:
1) keep 50cm away from robot
2) when the robot see's your moving away (and the distance to obstacle increases to more the 50cm), it tries to catch up.
Very impracticable and useless I'm afraid.

Best thing you could do is use a camera and do image processing / object recognition. My thesis was on something similar, you might want to have a look here, for some image processing ideas:
http://www.pocketmagic.net/?p=520

A better approach would be to use two PIR sensor, cheap and very reliable on day/night with a big radiu. You would need to mount them in the front part of your robot like:

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Basically the angle can be adjusted for larger view but the idea is as follow:
1) the robot is still
2) you're moving in front of the robot, and the PIR sensors detect the movement, but the signal will be stronger to one of the sensors (corresponding to whether you're in the front-left part, or the front-right part)
3) the robot moves 1-2m (pre-programmed distance) and turns left or right as indicated by left or right sensor and then stops
4) goto 1)

alternatively you can use the ultrasonic sensor to replace the reprogrammed distance at step 3.

[Joker94]

PIR would not be a bad idea i have neverused them. The reason why is simple, what if you went past another object with a similer thermal signiture, it would not neccesaryaly follow you. There erat he reason for I think sharp Infared would be more suitable and i remember another bot that did this and had good success with SharpIR.

And for image proccessing, as he said in his opening paragraph he is new to robotics and electronics there fore may have trouble building a circuit to support this as it may get advanced, not that i have done this, but if he wanted to buy a pre made MCU like the axon he did say he had programming backround.

[radhoo]

True.

For me funny thing, the first approach was the image processing, because that was the only thing I knew how to do (as a developer). My first robot  - a rc car, moved a wireless camera arround to sent the data back to a PC that analyzed the data and controlled the RC remote by LPT1 port.

I've just imagined an even better idea:

- HAL sensors (sensing the magnetic field), you would only need a pair mounted front-left and front-right (to be able to turn left / right) and a little magnet / or field generator circuit,  carried by the user.

the HAL sensors are easy to use, here's a datasheet of A1302:
http://www.datasheetcatalog.org/datasheet2/2/04940otsfigzd5t3wyz41sfwfwcy.pdf

Sure the are interferences sources, but this can be overcomed as well using modulation.

[Joker94]

would the halleffect sensors register if the person was holding a field circuit or similar, i am thinking it is to big of a distance to cover for the sensor as i could not find the range on the data sheet, from experiance the sensor would have to be much closer.

[radhoo]

Indeed, you are correct. The range is a big limitation of this design.

[Hawaii00000]

PIR would not be a bad idea i have neverused them. The reason why is simple, what if you went past another object with a similer thermal signiture, it would not neccesaryaly follow you. There erat he reason for I think sharp Infared would be more suitable and i remember another bot that did this and had good success with SharpIR.

Maybe the PIR might pick up some interference but the Sharp IR will make the robot go towad anything close to it including walls and other objects.

[blackbeard]

what if you have a leaking can of paint behind you and make it a line following robot >.>

[Admin]

http://www.societyofrobots.com/robot_faq.shtml#robot_track_person

[MangoBot]

having to photoresistors and led(color of your shirt) and compare which is brighter which will mean that you are more on that side then the other, could check up on the color sensor under sensors.