have you built the $50 robot?

[Admin]

Ive noticed dozens of people on the forum mentioning that they have built (or almost built) the $50 robot. I am really curious what your robots look like and was wondering if any of you could share pics and video of your robot in action. Also, do you have tips for others that plan to build it?

(I will put this post link at the end of the tutorial for others to get ideas, too)

[ed1380]

I have but don't have a digi cam.

http://i43.photobucket.com/albums/e398/RussianCommy/right.jpg
http://i43.photobucket.com/albums/e398/RussianCommy/trimetric.jpg
http://i43.photobucket.com/albums/e398/RussianCommy/boardtrimetric.jpg
http://i43.photobucket.com/albums/e398/RussianCommy/boardtop.jpg


Yes that's a gold ball 

[morgansaysthis]

hey i will be building it soon, and i will post images if i can find my camera


i just wanted to say thanks for such a great tutorial

[Admin]

ed, thats a really nice CAD of the circuit board (waaaay better than mine that I threw together)

this was made in google sketchup, right?

im not sure how files are saved on it, but is there a way you could share your files with us?

[ed1380]

Thanks. I did it in solidworks. Your datasheets helped alot. The reason I made all the componets seperate is because i was planning on making an animation of the robot being put together. kinda like

this	LQ | HQ

if you get the viewer you should be able to look at these files. (e-drawing came with solidworks, so I don't know if the downloaded version will work)
(you'll have to download all files for it to work properly)

[Bonzai Clif]

I and a few of my advanced physics students have got the $50 robot to work.  (The rest are frustrated but are motivated to finish since they have seen the working robots.  The robots avoiding shadows and following the flashlight are so cool)

It is an excellent path to learn the basics of soldering, trouble shooting circuits problems and software interfaces.

We are anxious to see if we can add more sensors to do other things.

Excellent work and effort to get your tutorial on the web site. 

Thanks so much.   I will send some pictures soon.

[claesson92]

Well, i'm going to build the 50$ robot. (Havn't ordered the parts yet)
http://earp.co.nr  <-- A little blog about the robot

[awally88]

Have everything except for the time! I have all the parts now which is awesome I finish exams in 2 wks and then summer holidays i plan to surf and build robots for 4 months!

[Alley]

I haven't built that robot yet (I'm a little new to this - I have never built any  ), but i really want to build it, and I'm in the process of getting the components and even the money. Where I live, shipping costs a bit more, and I'm still quite and young (and broke )

[ed1380]

whatever you do, don't cheap out on the programmer cable.
get the $34 one.
in the end you'll end up saving money

[fr4ncium]

I'm in the process of ordering the parts - sorta in the same spot as awally88, except I'm in the northern hemisphere preparing for Thanksgiving break.  I plan on working on the $50 robot and my connect-4 playing robot over the upcoming breaks. 

[garriwilson]

I finished my robot during the summer and it was a great experience. (except the money part hehe
$120).

It kinda worked but not what I would call working. It kept like shaking then one wheel was going faster than the other (did I mess up the program?), so it went in circles and I think I overburned the photoresisitors with my mom's hairdryer (my fingers were burning like you wouldn't imagine from the hairdryer and it barely worked to heat sink). Overall it was a great experience, painful but really fun. HAHA.

I will try to post some pics of my robot, I will really try to post a video. I have a lot of homework now that I'm in high school so please don't get mad if I don't keep my promise. I took my robot apart but I made it easy to reassemble so that won't be a problem. I think I did a pretty nice job on my FIRST soldering. It was neat. I'll take a pic of it.

Random tip on building: when you push in the microcontroller into the IC socket, push evenly from each side with your thumbs and grab the perf board with other couple of fingers. That way pins won't bend. If you decide to take the microcontroller out, use a knife or something, put it in the hole between it and the board, push up to even heights from each side back and forth. Then it should slide out. I think I had that problem because I had no alligator clips to hold the IC socket for me and I soldered it in crooked. Then it (the microcontroller) was rough going in and out.

Right now I need to go to bed, so I can't put any pics right now. Will do as soon as I have free time.

[dj sures]

i've built plenty of robots that cost about $50 . but, it has cost me hundreds to get to that point .. for years, i would have dreams and purchase parts that i didn't need, or couldn't use .

most of the issue was finding suppliers for parts or building material . i was always looking for motorized wheel/track bases to build off of . but then i found geared motors and wheel sets . then i found hobby shops which carry model plastics and construction materials .

then i found hobby shops with cheaper and smaller servos

then i found screws and bolts and glues and hot glue guns .

now i can think of something, and really design/build it from ground up . i have been meaning to put together a check-list and how-to manual to get ppl started . to give suggestions of how to locate the building materials . where to look . and what to buy . what to look for . and how to prepare yourself to build your dream robot .

i'm always up to share any videos/photos/programming tips/circuits .. that's why i searched for a place like this ...

[Admin]

i'm always up to share any videos/photos/programming tips/circuits .. that's why i searched for a place like this ...

I encourage posting anything inspiring or useful for others!

If you ever want to go all out, I can also set you up a members tutorial account.

[dj sures]

i'm always up to share any videos/photos/programming tips/circuits .. that's why i searched for a place like this ...

I encourage posting anything inspiring or useful for others!

If you ever want to go all out, I can also set you up a members tutorial account.

i'd like to take u up on that offer . i've been building robots for a while now but i've never belonged to a community before . this looks like a good place to start!

[maverick monk]

my $50 robot is nearing $100. the hobby rc engineer in me makes me design all my drivetrains to stand up to the abuse i throw at my rc trucks... so i built mine on tracks, its been delayed forever but it WILL work by christmas!!! if not, ill have to buy a robot because i need it for my sophmore science fair... lol

[unrooting]

I've started to build the $50 robot. Just need to modify and mount the two servos. Will post photos  once completed.

[bukowski]

WOOO HOOO!!! Finally done and in the nick of time.





OK, i wanted to see if I could get away from the caster idea, and just create a underhung $50 robot that was able to "balance" without one. It worked fine with the photoresistors, besides wanting to do a wheelie when if first got turned on (servos must have type D motors??), and small oscillations when it was turning.

Unfortunately, when I upgraded it with the Sharp IR rangefinder, those small oscillations caused the sensor to see the ground. Not good, so I added the plastic angle up front as a kind of reverse wheelie bar. Seems to work fine!

I used a breadboard, so I had to accommodate for the size of the thing, making for a wide wheel base.
The bottom brackets I cut from some perforated metal that I took off a flat panel monitor, along with the plastic angle.
The plastic piece is a sample we got from work for a govt project, I have no idea what it is. It is 3/8" thick, but it weighs less than 1/4" nylon or lexan. I milled down the sides where I mounted the servos a bit to get some more head room, and milled out the center slot for the scanning servo.  It is kind of a pain to mill plastic, because it has so much deflection it kept causing the piece to move or bend, making it chatter like crazy. Ill stick with metal from now on.
Anyways, now I plan to mess with the code a bit and turn it into a object-avoider. I think I can use most of the code from the edge finding Stampy Algorithm, but make the scanning servo continuously scan left and right, scans left when it detects an object while the robot turns right, then go straight and continue scanning when the object is past. Inside corners might be it's undoing, but I'll  burn that bridge when I get to it.

OK, thanks a ton to Admin, airman00, and HDL Dragon for the help, and putting up with my noobish questions.

[Admin]

Im so proud!

don't forget to post a video, and maybe a tutorial when you get your 'object-avoider' code working

as for those oscillations, if you put PID control on it, it shouldn't oscillate . . . PID basically removes the stop/start jerkiness that causes that problem

[maverick monk]

wooty woot! IR, sonar, H bridge and programmer should be here by next saturday!

[bukowski]

http://s236.photobucket.com/albums/ff16/robvandiver/?action=view&current=121107_1201.flv

http://s236.photobucket.com/albums/ff16/robvandiver/?action=view&current=121107_1157.flv

Hope those links work.

Ok, so this is $50 robot with the sharp IR rangefinder upgrade version 2: the object avoider.
Still working out some kinks, like I have to get the rangefinder with the longer range, and finding "the perfect range" to work with. Right now Im still autocalibrating it every time I turn it on. Im sure the code could be better, I just changed a couple of lines, but not too bad for someone that knows nothing about anything!

Code:

/****************************************************************************
*
*   Copyright (c) 2007 www.societyofrobots.com
*   (please link back if you use this code!)
*
*   This program is free software; you can redistribute it and/or modify
*   it under the terms of the GNU General Public License version 2 as
*   published by the Free Software Foundation.
*
*   Alternatively, this software may be distributed under the terms of BSD
*   license.
*
* $50 Robot with Sharp IR using Stampy Technology v1, May 19th, 2007
* Simple case-based method for a robot to do edge detection.
*
*
****************************************************************************/

//SoR Include
#include "SoR_Utils.h" //includes all the technical stuff

//global variables
int sharp_IR_reading=0;

int scan_thresh=0;//threshold value of scanning sensor

int scan_angle=30;//position of scanner, in units of servo command
int max_scan_angle=56;//maximum position scanner can rotate to (57)


//this function causes scanning servo to center on edge of object
void scan(void)
{
//lower (-) goes right
//higher (+) goes left
//30 far right, 50 straight, 56 far left (until it jams)



sharp_IR_reading=a2dConvert8bit(3);

if (sharp_IR_reading > scan_thresh)//object detected
{
if (scan_angle>41) //overflow protection
scan_angle-=2;//scan right
}
else //object not detected
{
if (scan_angle<=max_scan_angle) //maximum servo angle
scan_angle+=2; //scan left
else //if scanned all the way, this forces it to start over
scan_angle=30;
}

//servo scan code
servo_scan(scan_angle);
}


//automatically calculates threshold value before run
void autocalibrate(void)
{
scan_thresh=a2dConvert8bit(3);//sensor reading
}

int main(void)
{
//LED_on();

initialize();

delay_cycles(42000);//two second wait delay

/*********ADD YOUR CODE BELOW THIS LINE **********/

//find thresholds
autocalibrate();

//LED_off();


while(1)
{
scan();

if (sharp_IR_reading > scan_thresh)

robot_turn_right();


//object is centered
else
robot_go_straight();

delay_cycles(400);//a small delay to prevent crazy oscillations
}
/*********ADD YOUR CODE ABOVE THIS LINE **********/

return 0;
}


/*********************COMMAND LIST*************************

delay_cycles(cycles);
Delays - you can make your robot wait for a certain amount of time with this function.
Put the number of computational cycles to delay in the ().
23 cycles is about .992 milliseconds
to calculate: 23/.992*(time in milliseconds to delay) = cycles
Check servo datasheet where it says: 'Direction: Clockwise/Pulse Traveling 1500 to 1900usec'

servo_left(speed); and servo_right(speed);
Commands your servos to rotate at a certain speed.
Vary speed (which represents a delay in cycles) from 20 to 50.
Left is for port D0 and right is for port D1.

robot_turn_left(); and robot_turn_right(); and robot_go_straight();
Dont want to deal with speed?
Just call this function and it will 'just work.'

LED_on(); and LED_off();
Turns on and off your LED. The LED is on port D4.
By bringing port D4 low, you are turning on the LED.


variable=a2dConvert8bit(pin);
Reads analog pin. For example, set 'pin' to 5 to read PC5.
'variable' will store the value.

***********************************************************/

anyways, any suggestions for how I could make it work better or anything I did wrong are welcome!

[airman00]

the links don't work

but it sounds cool

the problem is you uploaded them from your phone. When you upload it from your phone it only lasts like a few hours online before it gets auto deleted. When you upload it , save the image from the verizon site onto your desktop and then uplaod the image to photobucket or something.

[bukowski]

huh. Thats weak.
Oh well, live and learn. They should work now.

I need to get a better algorithm. It works fine with large objects (a wall), the scanner scans all the way left and the robot turns right until it is past. With small objects though, and with it looking for the left edge of the object, it is only reading the object / turning about half the time.

Right now Im going to put a small delay after the robot_turn_right() command to help smooth it out. This will cause overshooting sometimes, but it's a quick fix.

[atmegaman]

I have been working on the $50 robot for about a month now; some good results, some weird, and some just plain hairpulling.  It's been a while since I soldered anything so I had to recollect some tools that had been lost during a recent home move.  All in all, the robot cost me over $50 (about $150 after reacquiring everything I needed  ).

A couple of observations first:
1.  The design of the controller is actually quite good and has a lot of features that are available to you once you get use to programming the atmega8.  The tutorials are great in that they can all be done with the Atmega8.  Again, knowing the features and how to implement them is the key.
2.  The programming can be a hassle and one can easily lock up the chip (as listed in other posts on this site plus others).  If you lock up a chip, don't feel bad..a lot of people have done it.
3.  My first board did not work correctly because of being too congested underneath (too many wires and using wires that were too big).  I stripped all the components off and put them on a proto board (RadioShack).  I also split the power from being just 4 AA batteries to the battery pack for the servos, plus a +9v battery (to drive the electronics) - both are rechargeable.  Adding a switch to control the electronics (and using the built in switch on the battery pack) is the way to go.
4.  Someone else mentioned that one has to build the programmer before setting the servos to 0 using the hex file.  This is actually a good way to learn both the programming steps and how to modify the servos.  This was actually my first success with programming the chip using the soldered board.  Just getting the board to be detected by the software was a thrill after so many attempts.  Reading through the formum posts here helped me a great deal.
5.  I took the concept of using chop sticks and used kabob sticks for my platform and the Digikey box for my wheels (figuring I bought so much from Digikey).  Its not very sturdy, but it proved the concept (I'll post picture at end of post).
I'll also use all the components for a future project.  I am going to work through the other tutorials (RS232, UARt, Vision, etc) so these parts will go a long way.  Good choice for a first robot!
6.  Now the programming- the biggest piece of advice would be to NOT load up the AVR software until the AVR programmer is plugged in with the green light on, AND the microcontroller development board you just built is turned ON.  You will know it is turned ON when both lights of the AVR programmer (6 pin USB) are green.  Thanks for all the posts about 6 pin vs. 10 pin and the pinouts of the programmer.  Again, this helped a great deal.  Also, once you have a decent project, you can use  the CONN icon on the tool bar (that lets you muddle things up if you are not careful) OR as I found out by accident, you can use the Tools/AVR Prog on the tool bar (which is a lot easier).  I recommend using the AVR Prog selection for everyone who is not yet comfortable with all the bells and whistles of the AVR software.
7.  I thought I had some bad atmega8 chips because they would never let me enter the programming mode (using the AVR USB programmer- $35 Digikey).  I used a serial port programmer today and was able to recover 3 out of 4 chips.  Now this was using the AVR Prog dialog box (Tools/AVR Prog) on the main window.  All one has to do is point to the correct *.hex file and it erases what is on your chip, writes the new program, and then verifies that it is correct.  Really painless.

Those are my thoughts so far.  Attached is a picture of my completed beastie.

Mike

[cooldog]

http://s236.photobucket.com/albums/ff16/robvandiver/?action=view&current=121107_1201.flv

http://s236.photobucket.com/albums/ff16/robvandiver/?action=view&current=121107_1157.flv

Hope those links work.

Ok, so this is $50 robot with the sharp IR rangefinder upgrade version 2: the object avoider.
Still working out some kinks, like I have to get the rangefinder with the longer range, and finding "the perfect range" to work with. Right now Im still autocalibrating it every time I turn it on. Im sure the code could be better, I just changed a couple of lines, but not too bad for someone that knows nothing about anything!

Code:

/****************************************************************************
*
*   Copyright (c) 2007 www.societyofrobots.com
*   (please link back if you use this code!)
*
*   This program is free software; you can redistribute it and/or modify
*   it under the terms of the GNU General Public License version 2 as
*   published by the Free Software Foundation.
*
*   Alternatively, this software may be distributed under the terms of BSD
*   license.
*
* $50 Robot with Sharp IR using Stampy Technology v1, May 19th, 2007
* Simple case-based method for a robot to do edge detection.
*
*
****************************************************************************/

//SoR Include
#include "SoR_Utils.h" //includes all the technical stuff

//global variables
int sharp_IR_reading=0;

int scan_thresh=0;//threshold value of scanning sensor

int scan_angle=30;//position of scanner, in units of servo command
int max_scan_angle=56;//maximum position scanner can rotate to (57)


//this function causes scanning servo to center on edge of object
void scan(void)
{
//lower (-) goes right
//higher (+) goes left
//30 far right, 50 straight, 56 far left (until it jams)



sharp_IR_reading=a2dConvert8bit(3);

if (sharp_IR_reading > scan_thresh)//object detected
{
if (scan_angle>41) //overflow protection
scan_angle-=2;//scan right
}
else //object not detected
{
if (scan_angle<=max_scan_angle) //maximum servo angle
scan_angle+=2; //scan left
else //if scanned all the way, this forces it to start over
scan_angle=30;
}

//servo scan code
servo_scan(scan_angle);
}


//automatically calculates threshold value before run
void autocalibrate(void)
{
scan_thresh=a2dConvert8bit(3);//sensor reading
}

int main(void)
{
//LED_on();

initialize();

delay_cycles(42000);//two second wait delay

/*********ADD YOUR CODE BELOW THIS LINE **********/

//find thresholds
autocalibrate();

//LED_off();


while(1)
{
scan();

if (sharp_IR_reading > scan_thresh)

robot_turn_right();


//object is centered
else
robot_go_straight();

delay_cycles(400);//a small delay to prevent crazy oscillations
}
/*********ADD YOUR CODE ABOVE THIS LINE **********/

return 0;
}


/*********************COMMAND LIST*************************

delay_cycles(cycles);
Delays - you can make your robot wait for a certain amount of time with this function.
Put the number of computational cycles to delay in the ().
23 cycles is about .992 milliseconds
to calculate: 23/.992*(time in milliseconds to delay) = cycles
Check servo datasheet where it says: 'Direction: Clockwise/Pulse Traveling 1500 to 1900usec'

servo_left(speed); and servo_right(speed);
Commands your servos to rotate at a certain speed.
Vary speed (which represents a delay in cycles) from 20 to 50.
Left is for port D0 and right is for port D1.

robot_turn_left(); and robot_turn_right(); and robot_go_straight();
Dont want to deal with speed?
Just call this function and it will 'just work.'

LED_on(); and LED_off();
Turns on and off your LED. The LED is on port D4.
By bringing port D4 low, you are turning on the LED.


variable=a2dConvert8bit(pin);
Reads analog pin. For example, set 'pin' to 5 to read PC5.
'variable' will store the value.

***********************************************************/

anyways, any suggestions for how I could make it work better or anything I did wrong are welcome!

just checking so could i just copy and paste the code to my ATmega 8 board and it will be a obstacle avoider

[skatj]

I have, it's actually a $300 robot though (corporately sponsored for a science fair project), but it looks similar to the $50 robot and borrows the water bottle as a third point of balance idea, which I thought was hilarious.

It's a ground-based prototype to test my autopilot code and will ultimately be a UAV based on the Multiplex Easy Star Airframe.
It uses the Basic Stamp 2, Parallax GPS Receiver, parallax Servo Controller, and uM-fpu v2 floating point coprocessor. (camera is an Aiptek SD 1.3 pencam, $20)

http://www.project-uav.net/images/prototype-top.jpg
http://www.project-uav.net/images/prototype-complete2.jpg
http://www.project-uav.net/images/prototype-complete1.jpg

[SgtToad]

He's alive !!!

I have finished and tested my 50$ robot.

Here are some pics. I post video this week-end.

http://public.fotki.com/DanielPoirier/50-robot-alive-!/

[airman00]

He's alive !!!

I have finished and tested my 50$ robot.

Here are some pics. I post video this week-end.

http://public.fotki.com/DanielPoirier/50-robot-alive-!/

nice clean job! Is this your first robot?

[cooldog]

He's alive !!!

I have finished and tested my 50$ robot.

Here are some pics. I post video this week-end.

http://public.fotki.com/DanielPoirier/50-robot-alive-!/

whats attached to the cd wheels

[SgtToad]

Yes it's my first robot, electronic, soldering etc project. I have a background with R/C and computer but never do electronic thing like that. The feeling when i switch on the switch the first time was amazing.

To add traction on CD i glued a stripe of under carpet stuff ( sorry if it's not the correct word, i'm not really good in english ).