human following sensors

[andd64]

Hey all,

I'm new to this forum but I've looked through posts and it's exciting to see so many people interested in robotics.  Im currently doing my undergrad thesis, and im going to be building a human-following robot.

I need help in picking sensors.  Any will do, i just need some that will give me the best results.  I have in mind IR, ultrasound, and even stereo-vision cameras, but i honestly don't know too much about them.  Any help would be appreciated!! (I tried searching for previous answers to this question but there weren't too many significant results).

Thanks in advance.

[ArcMan]

If you want something relatively simple and not too discerning, you could use an ultrasonic ranging device mounted to a hobby servo such that the servo pans the ultrasonic sensor.  There are mounting systems already for sale for this.  The idea is that you pan the servo around an arc while taking ultrasonic range measurements.  You record the minimum range out of the series and assume that's your human.  Then turn the robot to face the human.  Rinse and repeat.

[andd64]

that sounds good - thanks.. lets say i wanted something more complex?

[MadMax]

Well, you would have to think about what makes a human different from other creatures.

So, you got IR right, however, other warm-blooded animals would be detected too. So you would need a camera to determine the human shape. When you've found a human you can do a combined blob-tracking and heat-tracking to make sure the sensors keep following the human. Lastly, when youneed to follow the human, you would need to know the distance to the human. So you would need a range finder (sonar, IR) Combine the sensor inputs from these three sensors, and you'll have a perfect human tracker.

[ArcMan]

And if you want to do something like blob tracking, Roborealm has some great free software for that.  I've fooled around with it a bit.  You will need some computing muscle to run it.
It's great.  In just a few hours, I was tracking my cat around the room (he was the black blob).  You can have Roborealm output the position of tracked objects to the serial port and use that information to steer your robot.

[andd64]

blob tracking sounds good.  ok so lets say i do the three sensors.. would you guys have a recommendation on where to get the sensors from? or any kind of specific brand (one better than the other)?

software isn't too big an issue for me, i dont even mind creating my own (part of the work i guess lol).  but i do need to get a microcontroller.. is it worth it getting a super duty one or will a basic standard one do (lets say im using those three sensors and im running motors that will power lets say a wheelchair sized bot.  any controllers in mind?

thanks for your help guys.  this is kinda new stuff to me.

[ArcMan]

With all due respect, It seems like you might be biting off more than you can chew.  You're not familiar with robotics or sensing technologies or even microcontrollers, and you want to start with a human following robot?  That's a big leap!  You may want to start off with something like the $50 robot to get your feet wet.  That will get you familiar with microcontrollers and some sensing technologies.  From there, you could expand into tracking and vision.

[andd64]

well actually im new in the sense that i'm not familiar with certain types of sensors i.e. sonar, camera vision/tracking.  ive actually done a robotics course, ive built several robots: a line follower, flame extinguisher, object detection/avoidance, and small mapping.  the trouble is we were given a microcontroller but we had to do everything else ourselves. 

those things were easy to do though... so i understand microcontrollers, and basic sensors, which is why im doing this project now. 

[Admin]

A very common question here at SoR
http://www.societyofrobots.com/robot_faq.shtml#robot_track_person

You mentioned it was for a thesis. Whats your thesis title?
(building a neat robot, and doing useful science, aren't always the same )

[andd64]

wow i swear i read the faqs and completely skipped over that  . 

well my thesis is basically on social awareness and a human following robot.  That kinda means that the robot has to be aware "socially" - like humans who understand what another human means or wants based on actions or emotions.  so eventually i'll be programming some "smart" a.i into it to be able to be socially adept and aware.

but i guess the first step is to be able to follow a human around, right?

camera vision will be my main sensor, and an IR and a range finder as my secondary (thanks to MadMax and ArcMan for this) sensors.  But what im concerned about now is what kind of camera I should use.  I read through this site a few bad comments about the CMUcam, so I'm right now at a standstill.  If I want results (and i do) should i invest in either a CMUcam or AVRcam or a good webcam (or some other sort of camera)?  What's your opinion?  (Let's say i have a budget of $50-100 for the camera alone).  I guess I'd have to add some sort of wireless adapter too then - esp if i use RoboRealm?  Any recommendations?

[ArcMan]

For Roborealm, I just used a cheapo web cam (Logitech) and it worked fine.  The CMUCam and Black Fin come with cameras, I believe.

[Admin]

If you are doing AI, you'd probably find the laptop + webcam + roborealm route the simplest and with the most capability. You might want to use multiple sensors for 'double checking', like an infrared sensor to detect body heat.

Let's say i have a budget of $50-100 for the camera alone

My webcam was like $60, but if you go with Blackfin or CMUcam, expect to spend more like $150-$250.

[andd64]

that sounds like the best solution.  Let's say I don't have a laptop that i can attach to the robot - will it be ok to wirelessly send the video to a nearby computer?  Or should i strive to get a laptop and phsyically connect it to the MCU?

[Admin]

You might be able to find a wireless webcam (I remember reading somewhere about it in the forum).

will it be ok to wirelessly send the video to a nearby computer?

Yeap. Look into a TV tuner card for your PC combined with an analog wireless camera. This forum has info on it, just search around here and on google.

[andd64]

I read the FAQs page on roborealm, they suggested staying away from the NTSC transmission method, and try to use an internet camera instead.  Any thoughts on this?

(http://www.roborealm.com/FAQ.php#q10) faq 1

Either way if i use a NTSC or internet camera, i would still need a wireless connection to the MCU right? I read the "Where Do I Connect Bluetooth On My Robot?" on the bluetooth wireless faqs page, and from what i understand is that i can either do it by connectting a bluetooth device directly to the microcontroller by either a rs232 serial interface or through the UART tx/rx pins - so which way would be the cheaper way? (I still haven't bought a MCU so the options are open but I would definintely need a wireless transmission capability)

[Admin]

I read the FAQs page on roborealm, they suggested staying away from the NTSC transmission method, and try to use an internet camera instead.  Any thoughts on this?

(http://www.roborealm.com/FAQ.php#q10) faq 1

Both options 1 and 2 look ok. You'll probably find those additional adapters and other components to be a bit expensive or have compatibility problems. Look around to see what you can buy and how affordable it is for you, and google around to see if others have reported their experiences.

by either a rs232 serial interface or through the UART tx/rx pins - so which way would be the cheaper way?

directly to the UART