Instructables
This Instructable covers the conversion of a cheap off-the-shelf RC truck into a powerful robot vision platform capable of ball following, etc.

I always like seeing the projects around the world using expensive robots, running complex vision processing software and dreamt of the day I would have my own to play with.

Win the lottery or build one on the cheap?

Cheap wins every time.

I say cheap, but what I mean is cheap-ish. It depends on how complicated you want it to be and how much you have lying around. Maybe it should be "cheap compared to a Corrobot or Whitebox robot" (although they have much more functionality)

Anyway.

Parts required

Toyabi Skullcrusher RC monster truck
SSC-32 for webcam tilt
Logitech Pro 9000 webcam
Sabertooth 2x10a speed controller
Dell C610 laptop system board + proc + memory + wireless
12v - 19v converter to run laptop from 12v SLA battery
12v battery (I used a 12v SLA 7ah but its a bit too heavy, maybe a LIPO?)
RS232 - TTL converter (homemade or Ebay) for Sabertooth
USB - RS232 converter for SSC-32
Remote control unit and keyfob (homemade or Ebay) - this is a failsafe so I can cut power to the Sabertooth
USB hub
12V fan
Old satellite set-top box - emptied this and used it as a box to house it all in.

Software

Windows Xp
Roborealm
UltraVNC

 
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Step 1: Sourcing the RC truck

Whilst surfing Ebay one day I came across new RC monster trucks selling very cheaply. The interesting thing about them was that they had tank-style steering instead of the normal Ackerman steering like most RC trucks.

They can be bought in Europe from Seben racing and in the USA from Amazon and are called "Skull Crusher" from Toyabi.

http://www.amazon.com/Remote-Control-Scale-Monster-Yellow/dp/B000ODT7RK

Here are some videos of the trucks in action

http://www.wilhelmy-it.de/seben/pictures/racing_king/king.html
http://www.youtube.com/v/GFLU0xfkD3s&hl=en

I had a good robotty feeling about these asked my better half to get me one for my birthday.

The truck is HUGE and comes with a simple speed controller which is on/off rather than proportional, still, it was amazing what could be achieved with such a cheap model.

Stock, it will spin on the spot, climb all sorts of objects and gradients.

It has independent suspension and gearing to each wheel and runs from two small-ish motors. It is VERY big and came in an enormous box.

Construction is better than expected for such a cheap model, but the tyres are some kind of foammy PVC moulding. Apart from that, lots of space on board and has springs at each corner. The transmission is by gears down 4 articulated arms to the wheels.

Step 2: Stripping down

1st job was to strip it apart and remove the old speed controller and replace it with a Sabertooth from Dimension Engineering. You need to cut off the Electrolytic filter capacitors from the motors as they will blow under PWM motor control. Leave the ceramic capacitors in place to filter out some noise.

The body shell comes off easily and the lights disconnect via a small connector. I cut out the rest of the controller and receiver circuitry.

I added the Sabertooth temporarily and set it up for RC mode and an old 27Mhz proportional set I had lying around to test with. All ok, had even more fun driving it around under proper proportional control :)

It can move very quickly

http://www.youtube.com/v/Qdr3425YmsA

And with the new speed controller, very slowly too !!

http://www.youtube.com/v/U5EEBoXVQ-Y

Step 3: Adding the brains

DSCN1141.jpg
image001.jpg
Next step was to add a brain to the system.

An old Dell C610 laptop I had lying around was dis-membered and the system board, memory and processor saved for the robot.

An old satellite set-top box served as the case for the project and mounted pretty easily to the top of the truck. I then mounted the system board and Sabertooth controller inside, along with a 12V 7AH SLA battery (slung under the casing), DC-DC converter to power the laptop from 12V and a failsafe.

The failsafe is a small 433Mhz key fob transmitter to cut the power to the motors if the robot should decide to make a break for freedom. It's a simple RC switch bought from Ebay very cheaply and used to toggle power to the Sabertooth.

I also added a small 12v fusebox and wired it all up with some cable from an old PC PSU.

My 8 year old webcam was rubbish so I went out and bought a Logitech 9000 PRO, which is very good and came on a tilting base which started me thinking that I could control it from the laptop via a servo to tilt the camera as the robot adjusted its distance from an object.

I used an SSC-32 servo controller from Lynxmotion to drive the servo and connected the controller to the PC via a USB to serial converter (I had already used up the laptops COM1 serial port for the motor controller)

The Dell laptop only has one USB port so I added a small hub to allow the USB to Serial module and the USB webcam to connect at the same time. With hindsight, I would have surfed Ebay for a Laptop system board that had USB 2 instead of 1.1, but it was all I had and works well for now.

The COM1 to Sabertooth cable needs to have a Serial to TTL converter fitted, you can find these on Ebay for under $10 or make your own as I did. This converts the RS232 levels to a lower 5v level suitable for the speed controller inputs.

I also added a chunky power on/off switch and soldered a remote pushbutton switch to the power button of the laptop. (Could have just drilled a hole in the case and used a prodder). A small 12V fan was added to the case to help cool down the laptop system board which isn't used to running without a case to direct the airflow.

The laptop had a Wifi card to enable me to remote control the robot from another laptop for making adjustments, etc without having to hook up a keyboard/mouse/monitor to the robot.

Step 4: Software install

Picture of Software install
I installed the XP and the Dell drivers on the laptop and installed a free bit of software called Roborealm which is a great visual processing program intended for robotic applications which just so happens to have an SCC-32 and a Sabertooth module in-built. Joy !!

(Update: Roborealm was free, but they have started charging for its use, luckily not too much)

http://www.roborealm.com

There is an example green ball follower script that you can download from the Roborealm website that I modified slightly to work with my hardware and I spent a few hours tinkering with the settings in the filters until I had it as good as i could get it.

I also downloaded the free software, UltraVNC, on the two laptops which allows me to remote into the robot and make adjustments or just watch what is going on on the screen and webcam.

http://www.uvnc.com/

Step 5: Testing

The next day after finishing it, I took the robot along to a robot event and tested it out by gently kicking a green ball along the floor and watching the robot following it where ever it went. It can go forward, left, right and it backs away if the ball comes towards it. I had one finger on the failsafe remote at all times.

It only shot off once when it liked the look of the green trees through the window. A quick tweak of the color filter's Hue setting fixed that.

Not a finished project by any means, but a great platform to have a bit of fun and test out all my odd ideas for sensors, etc.

If you have an older laptop lying around (about PIII 1Ghz) and any kind of PC driven speed controller then you can set this up fairly quickly. Make it as simple or as complicated as you wish. No real programming required, just tweaking of scripts, etc

My next steps are to add some sensors (ultrasonic and IR) to the robot and swap the heavy Lead-acid battery for a LIPO to ease some of the weight from the suspension.

I may have a stab and reverse Engineering the ball follow script and add the sensor inputs from the SCS-32 into the Roborealm program loop.

Remember the failsafe. This robot can move fast and is quite heavy. Could easily cause injury if it escapes and runs amok.

If you need any more detail, just ask. I will try to help in any way I can.

Have fun.

(For the video below, I modified the script to follow an orange ball as green balls don't work to well on grass. I wish I had taken a video from the robot event as they had large open floors where I kicked the ball off slowly and watched it roll a long way with the robot in hot pursuit !!)



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Where did u find all these parts
OracsRevenge (author)  bradley1marler2 months ago
Amazon and Ebay
mike01010110 months ago
im using pwm to drive the sabertooth w/ 9.6v source..doesn't seem to generate enough power to turn the vehicle properly. Wondering if i should be using a larger battery..
Do you know how much voltage and amperage the motors require?
OracsRevenge (author)  mike01010110 months ago
This was a few years ago. I used a 12V 7aH lead acid battery, but replaced it eventually with an 11.1v 4aH LIPO which worked well.

I never measured the current draw but at a guess you would need to supply a peak current of around 5 amps.
Hi i'm looking at starting in robotics and was wondering if anyone knew where I can get a cheap RC robot kit or cheap parts to build one. I have basic soldering skills but no programming skills.
OracsRevenge (author)  TheUntrained1 year ago
Hi, you may be better starting with something like Lego Mindstorms or Vex, there are communities out there for support and ideas,. Thanks
brenryan2 years ago
Hi Oracs,

Nice build.

I'm trying to do something similar, using a single board linux computer to make a remote control rover style robot.

Like this:

http://www.instructables.com/id/Mobile-Earth-Rover-35G-Exploration/

I'm also using a Toyabi Skullcrusher and I will be going with a camera setup similar to yours rather than the above.

I was wondering if you could please post or PM a few more detailed pics + instructions of the camera mount and servo assembly.

It would be a great help for me if you could show how you did it to get some ideas going. I may have to try and modify it to have pan and tilt, but this would be a great starting point for me if it's not too much trouble.

Many thanks mate, keep up the good work...
OracsRevenge (author)  brenryan2 years ago
Hi,

Sorry, I have had a check and I don't have a better photo available.

The tilt was achieved by drilling and screwing in a small ball joint to the camera and using a wire link to a servo to tilt up and down.

This didn't work particularly well and if I was to do it again, I would by a simple pan and tilt set-up similar to this

http://www.trossenrobotics.com/store/p/3139-Pan-and-Tilt-Kit-with-Servos.aspx

Thanks
So you were able to control it complete from the dell pc using Roborealm?

For someone with no experience using a Sabertooth speed controller, would you say that would be easier than using an Arduino UNO and motor controller?

Thanks! Awesome bot
OracsRevenge (author)  tommytwoeyes2 years ago
Hi,

Roborealm has an inbuilt control module for interfacing with the Sabertooth so there is nothing to learn for it, you just need to tweak some of the variables in the module to get the right responses.

The entire robot is controlled from RR, even tilting the camera up and down (via the Lynxmotion servo controller)

Roborealm really needs to be run on an onboard PC, if you are using an Ardunino, you could possibly use it as a control/sensor slave for the robot back to a base PC running RR.

Thanks
Thanks man.

Would any typical laptop PC board work? What are the minimum system requirements for the board in a bot like yours?

Tom
OracsRevenge (author)  tommytwoeyes2 years ago
The better the board, the more frames per second Roborealm can process.

This leads to faster and more accurate control of the robot.

If I was making the robot again, I would use a cheap Netbook running windows. as they are much easier to power and you can see the results on the Netbook screen.

You can still slave using openVNC to another laptop so you can see what it's doing and take control at a distance if you need to.

You are probably best to download the trial version of Roborealm and play around for a while with a webcam.

It sounds like really awesome software. Thanks for your advice!
Dearden8053 years ago
Whats the total cost???
vicky6663 years ago
(removed by author or community request)
so then how come you haven't done it yet? where is your instructable on it?
exactly.
MCzone zack2473 years ago
he has nothing against his desighn, or he does not know how
hintss vicky6663 years ago
well, I found out, from reading that, that electrolytic capacitors blow under PWM. evidently not a waste of time for me. I also found out about roborealm.
Dude don't hate. If you don't like it, then don't hang around long enough to post a comment. Or contribute and make it better. One of the reasons I like this website is because everyone's usually friendly
it is working without remote
it is computer controled
NAWWWWW YA THINK?
jssteinke4 years ago
When I do this, I'm going to program it in labview. :) NI vision assist is easy to use.
yuck! dont waste your time with that garbage software! i used it when i was doing frc in school and it was soooooo limiting ! go check out c# 2008 and openCV it'll blow your mind! plus you dont have to own that silly compact Rio. 700 dollar paper weight!
Haha, i respect your descision, I'm in FRC too! I am just saying that vision assistant is very easy to use, i would like to (re)learn C#, i have used C dialects in the past. I've been wanting to write our code in the C IDE, that comes with the FRC KOP, but it'd be easier for newbies to learn labview, so i have to continue the legacy, lol.
yeah its just that all the frc stuff is sooo cushy! it never gets down into the nitty gritty of device i/o, everythings all wrapped up so in a way it is fast to code for their platform but so limited. but seriously check out c# its very intuitive and super easy to learn because the ide suggests code for you.. BTW GO BUY AN ARDUINO! learning how to code on that is awsome because its sooo similar to other languages, java, c ,c++, processing, ruby, perl...
our cRIO isn't detecting battery voltage, even though it turns on. any help?

anyway, I think that the cRIO is a form of a PLC, isn't it?
Yeah the cRIO is a PLC, it is mainly used as a FPGA, but also has a ARM or something in it. One thing to try is to make sure your analog input board is connected to the right slot, and the module in that slot is right. i think its a 9134 or 9234 or something like that. The smaller connector. The cRIO cant read the voltage you give directly to it though, it can only read the voltage on the analog slot. Also make sure on the analog breakout board, the big 2 pin connector is connected to your power distribution board. If this dosent help, just ask for more help.
well, we moved the parts around, and it still wouldn't work.

anyway, where exactly is the voltage read again?
oh, also, the motor controllers are blinking red, could this be related?
and the thing without the repurposed parallel port goes on the side with ethernet, right?
The voltage isnt read from the voltage coming into the ethernet side of the cRio with the 4 pin connector thing. The voltage is read using the Analog Breakout Board wich plugs into one of the crio modules. You can look at the FRC control system manual here http://www.usfirst.org/uploadedFiles/Community/FRC/Game_and_Season__Info/2010_Assets/3-2010FRCControlSystemComponent%20DatasheetsRev1_enc.pdf

a
lso try looking at the cRio manual http://decibel.ni.com/content/docs/DOC-2632

I
f you still need help just ask

so the analog board is the one with a red PCB connected an top, right?
Yes it is
Also, the motor controllers should always blink red when idle. The only stay solid colors when you send FOrward/Backward commands
Yeah, i have an arduino, and have created lots of awsome things on it, our FRC team was thinking of using it instead of the cRIO, for the fun of it.
haha! ive done that too! its actually way easy to convert the hardware to work with a arduino, just take your time and make some custom connectors on a protoshield to your arduino, also i used a computer with vspe installed to remotely drive the robot through a adhawk network
Thanks for the idea, weve been trying to find a way for wireless communication, we'll probably use the ethernet shield. Something fun we were thinking of doing for some school cred, would be to put the frc bot on our schools wireless, then just drive the robot around using the IP cam for wireless vision
dude! thats also what i did! hey if you want some software to drive the whole thing email me! i wrote it all in c# (-arduino code)
I'll pm you soon, hope to hear from you!
[corosive]3 years ago
is it really expensive?
in jimmy neutron cartoon
it is a pet of jimmy names goddard
it is like a dog
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