Follow me robot

:confused: Please tell me if it is possible to make a robot follow a signal. For example: the robot would constantly go in the direction of a device on my key chain or in my wallet. Is this possible?

maybe is you use a couple light sensors that are pointed in different direction and have the robot move towards the greatest light reading, say, from a flashlight.

oohhh man u gave me great idea though i dont have parts to build.
use only the receiver plug from the ultra sonic sensor and find something else with the same mhz sound or whatever and set that robot to move towards it of course

What if i used components other than vex. What would be the best way in your opinion to achieve the key chain (or something similar) result? I have searched the internet but cant find an easy solution to this problem.

try a digital compass and carry around a huge magnet:D

i got another idea
ask vex to create a sensor that follows (strong) magnetic activity

well I guess i asked a question that nobody can answer. I thought i would be inundated with ideas and all i got was sarcasm.

okay, i wasnt joking when i said a magnetic sensor, which is a digital compass, because that would be one solution:mad:. but there isnt any other wasy i can think of to make a robot follow something it cant see. sure, if you wanted to make this task a bit easier you could have it follow a green light on the back of your shirt with the CMUCam, but that is kinda hard to program. there is no “easy” solution to this problem

When you tell me how high “Up” is, I’ll answer your question…:slight_smile:

Your question is poorly worded, and that is one reason why you are getting few replies.

It is dead easy to make a Vex bot follow any thing, if you know where the thing is.

It is big-time hard to implement a sensor that will tell the vex bot, in 3 dimensions, with “good” accuracy and precision, where that “thing” is; and also be able to distinguish (often enough) the thing from other similar objects

You need to start thinking about ways to remotely (no contact) sense the properties/presence of an object, and about ways to convert the sensor(s) measurements into an estimate of the object’s location.

Narrow your question down to some specifics and I suspect folks will be able to help you brainstorm a good approach.


I’d say you use two ultrasonic sensors and put one on the robot and wire up one and put it on you somewhere

… only would it have to be pointing at the robot…


I appreciate the help guys, sorry if i sounded like a jerk. I have learned a lot from this site in a short amount of time.

I would put very bright IR LEDs on the back of my shirt and use a vex line tracker kit. The line tracker kit senses IR light and since three come in a pack, it may be easier to detect the location of your IR shirt.

PS this may also work with tracking IR from remotes

Hope this helps!:smiley:

I would try RFID, you would have to adapt your own sensor but with a combination of the iultrasonic sensor I believe you could make a pretty good system.

Or have a tracking system on you and then have it send data wirelessly to the robot, then the robot moves based on your path.

I would personally use a heat seeking sensor that could detect you (human body temperature) and follow you around. THis can be done because there was an article in Robot Magazine about a robot that was programmed to follow a cat.:slight_smile:

Good luck


that would be amazing!

I have been looking to do the same thing. I found this

and it’s just the thing, except I don’t need the horsepower that this thing has. I would also like to make some design changes, etc.

I am curious as to what you want to use this for?

I would try RFID, you would have to adapt your own sensor but with a combination of the iultrasonic sensor I believe you could make a pretty good system.

Method 1
I think using two ultrasonic sensors separated by about 1 foot would give you enough angle resolution to do pursuit tracking. Use one sensor to trigger a pulse and then measure the time difference between the two receiver return signals using interrupts. This is a technique of passive angle detection. Assuming you can resolve distances of about 1 inch, this would give you about 5 deg angle resolution. The angle = arcsin(d/l) where l is the sensor separation and d is the difference in distance computed by multiplying the time difference by the speed of sound. You can do the ranging to target based on either sensor using the normal ultrasonic ranging software.

So hook up both sensor receivers to the interrupt ports as usual and measure the time between interrupts after the ranging pulse has been sent.

This requires that the receivers of both sensors be active continuously. I think this is the case but not sure.

It might be possible to double the range by using a sonic transponder on the target. However, timing delays in the transponder… i. e. receiving a pulse, and then triggering an echo pulse would have to known and be very repeatable over time.

Method 2:
This requires a hardware front end that can measure phase difference between two continuous sonic waves. The target is given a transmitter that transmits continuously and using closely spaced sonic receivers (less than .5 wavelength) , you can measure the phase difference using a phase discriminator. This phase is proportional to “d” and angle is again arcsin(d/l).
You might use a carrier of around 15khz (about .8 in wavelength) and put the sensors about .4 inches apart. This would give you double the range capability since it is one way. As you got in close, you could be using the vex 40khz sonic ranging to measure range.