Introduction: Arduino Controlled Servo Robot (SERB)

What better way to start experimenting with open source micro-controllers ( Arduino ) then by building your very own open source robot ( CC (SA -BY) )?

What to do with your SERB?
  • (here) - How to connect your SERB to the internet and drive it over a Skype video call.
  • (here) - How to Control Your SERB Using a Wii nunchuck's accelerometers
  • (here) - How to Add Obstacle Detecting Whiskers to Your Robot
  • (here) - How to make 30 kits (Open Manufacturing)

  • Fully programmable using an Arduino Duemilanove micro-controller (or another micro-controller of your choosing).
  • No need to solder.
  • Choice of cutting options for acrylic pieces. (scroll saw, access to a laser cutter, purchasing pre-cut pieces)
  • Easily expandable and modifiable with extra bolt holes and included breadboard.
  • Dual ball bearing rear wheel.
  • Up and running in 1-2 hours. (from kit)
  • Open source design (build as many as you like)

(Shameless Plug)
In the UK and like Arduino stuff? check out our newly opened web store

A quick video of a completed Arduino controlled servo robot - (SERB) running the included test program (step 6)

Note: Source files are available on a parallel Instructable (Source Files For) - How to Make an Arduino Controlled Servo Robot - (SERB)

Step 1: Parts & Tools

All bolts can be found at your local Home Depot. The other parts can be found online (I have included a link to my favorite source for each).

Parts List:

A bundle containing all hardware items can be purchased at's store (here) ($120)

Nuts and Bolts:
  • 3mm x 15mm bolt (x20)
  • 3mm x 10mm bolt (x12)
  • 3mm nut (x34)
  • 3mm washer (x12)
  • 8mm x 25mm bolt (x2)
  • 8mm nut (x2)
  • Skate Bearings (x2) ( VXB ) (these are standard skate bearings so they can be salvaged from a pair of roller-blades or a skateboard)

  • Large O-ring (4.5" ID 3/16" Bead Dash #349) (x2) ( McMaster-Carr Product #9452K407 )
  • Small O-ring (3/4" ID 3/16" Bead Dash #314) (x1) ( McMaster-Carr Product #9452K387 )

  • AA Battery (x4) (not included in kit)
  • 9v Battery (x1) (not included in kit)

(all wire is 22 AWG solid I purchase mine through McMaster-Carr )
  • 15 cm Purple (x2)
  • 15 cm Black (x1)
  • 5 cm Black (x2)
  • 5 cm Red (x2)

  • Screwdriver (x1) (Philips)
  • Needle-nose Pliers (x1)

Step 2: Cutting Pieces

Please chose which steps to follow based on the cutting option you have chosen.

Option 1 (Purchasing Pre-cut Parts)

  • Purchase a pre-cut chassis from's store ( here) ($60 including shipping to the USA and Canada)

Option 2 (Digital Manufacturing (ie. Ponoko ) / Access to a Laser Cutter)

  • Download the laser cutter layout ( "03 SERB Ponoko Cutting Layout P2.eps" or "03-(SERB)-Ponoko Cutting Layout (P2).cdr" )
  • Cut the files using Ponoko or on your own Laser Cutter (using 3mm, .118" acrylic (sometimes sold as .125")

Option 3 (Scroll saw and Drill)

  • Download and print the PDF pattern (please choose the file corresponding to your paper size) 03-(SERB)-ScrollSaw Pattern (letter).pdf03-(SERB)-ScrollSaw Pattern (A4).pdf(it is important to not scale the drawing while printing)
  • Measure the ruler on the printout against a ruler you trust, if they do not match the pattern has been scaled and you need to look at your printer settings before reprinting. If they do match up, onwards.
  • Glue the pattern to the acrylic sheet (3mm, .118" (sometimes sold as .125").
  • Drill holes.
  • Cutout pieces using a scroll saw

Step 3: Assembly

Congrats on making it this far 90% of the process is complete just download the assembly instructions on this step (04-(SERB)-Assembly Guide.pdf) & after a little lego/mechano style assembly you'll be ready to wire.

To entertain you along the way here is a time-lapse of my assembly:

Step 4: Wiring

With all the big pieces together its time to add the little electric veins which will allow our robot to be controlled. To do this download and print the wiring diagram (05-(SERB)-Wiring Diagram.pdf). A first glance at it can look quite daunting, however if you make each connection sequentially and take your time it comes together remarkably quickly.

The wiring is quite simple and no harm can come to your circuit until you add batteries. So wire everything up double check it, then add power.

Step 5: Testing & Troubleshooting

If you ordered a kit your Arduino has come preloaded with a test program. Just put in 4 AA batteries and plug the 9v battery into the Arduino. And if everything has been done correctly your robot will begin moving (it will turn in a random direction for a time between 0.1 and 1 second before going forward for a random time between 1 and 2 seconds then pause for 2 seconds before starting again).

If you have not purchased a kit an additional step is required. Download the attached zip file (07-(SERB)- SERB-Test Arduino Then unzip it in your Arduino sketch directory (default "my Documents\Arduino\") and download it to your arduino board. (if you are new to Arduino jump ahead one step where there are links to great getting started tutorials)

Common Problems:

My SERB moves slowly when it should be stopped.
This is a result of your servos not being calibrated quite right, to calibrate your servos wait until your program has the servos stopped then with a small screwdriver turn the potentiometer inside the servo (the little opening in the servo casing just above where the wires are). Rotate it either left or right until the servo is truly stopped.

Things aren't quite working properly.
Send us an e-mail with your symptoms and we'll try and help you out, while you're waiting for a reply double check all your wires with the wiring diagram from step 4.

If you encounter any problem please either add a comment to this Instructable or send an e-mail to and we'll try our very best to help you get your SERB working

Step 6: Programming

The physical robot is finished time to start giving it a brain.

Before we get into the details of programming an Arduino Controlled Servo Robot - (SERB) - a few links to some excellent Arduino programming resources on the internet.

Arduino Starter Guide - A guide to help you start with Arduinos, from downloading the programming environment to writing your first program.

Arduino Programming Reference - A complete easy to reference guide to the Arduino programming language.

How Servos Work - A quick primer to how servo motors work.

Arduino Servo Library - How the Arduino Servo library works (how we control our servos).

Alright with the learning out of the way lets get programming. There are three ways to get started programing your Arduino Controlled Servo Robot - (SERB).

Option 1: (Modifying SERB_Test.pde)
Sometimes when programming the easiest thing to do is take a working program and start adding your own code to it. To do this download the SERB_Test zipped program (07-(SERB)- SERB-Test Arduino Proceed to unzip this in your Arduino sketch folder (default "My Documents\Arduino\"). Finally open the Arduino programming environment and download it to your Arduino. The code is well commented.
(or copy and paste the code from the appendix on this step to a new Arduino Sketch)

Option 2: (Adding SERB Routines to your program)
Add some simple routines to your pre-existing program (like goForward(), setSpeed(int) etc.). To do this download the routines in the text file (07-(SERB)- Simple Routines Text.txt).
1. Copy and paste the preamble portion to the beginning of your program.
2. Copy and paste the routine portion to the body of your program.
3. Add a call to serbSetup(); to your setup() routine.

Option 3: (Creating your own program from scratch)
This is not too difficult. All that is required is to familiarize yourself with the Arduino Servo Library. Then the right servo is connected to pin 9, and the left servo to pin 10.

note: Additional programs will be added here as they are developed; or if you develop something and would like it featured send me a private message and it can be added.

Appendix: (SERB_Test.pde Code)

/* * Arduino Controlled Servo Robot (SERB) - Test Program * For more details visit:  *  * Behaviour: A simple test program which causes the SERB *            to turn randomly either left or right for a  *            random time period between 0.1 and 1 second. *            The SERB will then drive forward for a random  *            time period between 1 and 2 seconds. Finally *            pausing for 2 seconds before starting again. * * Wiring: Right Servo Signal - pin 9 *         Left Servo Signal - pin 10  * * License: This work is licenced under the Creative Commons  *          Attribution-Share Alike 3.0 Unported License. To  *          view a copy of this licence, visit  *  *          or send a letter to Creative Commons, 171 Second  *          Street, Suite 300, San Francisco, California 94105,  *          USA. *         */  //--------------------------------------------------------------------------// START OF ARDUINO CONTROLLED SERVO ROBOT (SERB) PREAMBLE#include <Servo.h>#define LEFTSERVOPIN  10  #define RIGHTSERVOPIN  9Servo leftServo; Servo rightServo; int speed = 100; //sets the speed of the robot (both servos)                  //a percentage between 0 and 100// END OF ARDUINO CONTROLLED SERVO ROBOT (SERB) PREAMBLE//--------------------------------------------------------------------------/* * sets pins to appropriate states and attaches servos. Then pauses * for 1 second before the program starts*/ void setup()                  {  serbSetup();                       //sets the state of all neccesary                                      //pins and adds servos to your sketch  randomSeed(analogRead(0));         //sets the random number seed with                                      //something mildly random  delay(1000);}/* * turns the robot either left or right (randomly) for a period between  * 0.1 and 1 second. Before going forward for a random time period  * between 1 and 4 seconds. Before pausing for two seconds then starting * again.*/void loop()                     {   turnRandom(100,1000);            //Turns randomly left or right for a                                     //randomtime period between .1 second                                     //and one second   goForwardRandom(1000,2000);      //Goes forward for a random time period                                     //between                                     //1 and 2 seconds   goStop();                        //Stops the robot   delay(2000);                     //pauses for 2 seconds (whilst stopped)}/* * turns the robot randomly left or right for a random time period between * minTime (milliseconds) and maxTime (milliseconds) */void turnRandom(int minTime, int maxTime){  int choice = random(2);                     //Random number to decide                                               //between left (1) and right (0)  int turnTime = random(minTime,maxTime);     //Random number for the pause                                               //time  if(choice == 1){ goLeft();}                 //If random number = 1 then turn                                               //left  else {goRight();}                           //If random number = 0 then turn                                               //right  delay(turnTime);                            //delay for random time                         }/* * goes forward for a random time period between minTime (milliseconds) * and maxTime (milliseconds) */void goForwardRandom(int minTime, int maxTime){  int forwardTime = random(minTime,maxTime);  //determine a random time to                                               //go forward  goForward();                                //sets the SERB forward  delay(forwardTime);                         //delays for random time period}//------------------------------------------------------------------------//START OF ARDUINO CONTROLLED SERVO ROBOT (SERB) ROUTINES/* * sets up your arduino to address your SERB using the included routines*/void serbSetup(){  setSpeed(speed);  pinMode(LEFTSERVOPIN, OUTPUT);     //sets the left servo signal pin                                      //to output  pinMode(RIGHTSERVOPIN, OUTPUT);    //sets the right servo signal pin                                      //to output  leftServo.attach(LEFTSERVOPIN);    //attaches left servo  rightServo.attach(RIGHTSERVOPIN);  //attaches right servo  goStop();}/* * sets the speed of the robot between 0-(stopped) and 100-(full speed) * NOTE: speed will not change the current speed you must change speed  * then call one of the go methods before changes occur.*/ void setSpeed(int newSpeed){  if(newSpeed >= 100) {newSpeed = 100;}     //if speed is greater than 100                                             //make it 100  if(newSpeed <= 0) {newSpeed = 0;}         //if speed is less than 0 make                                             //it 0   speed = newSpeed * 0.9;                   //scales the speed to be                                             //between 0 and 90}/* * sends the robot forwards */void goForward(){ leftServo.write(90 + speed); rightServo.write(90 - speed);}/* * sends the robot backwards */void goBackward(){ leftServo.write(90 - speed); rightServo.write(90 + speed);}  /* * sends the robot right */void goRight(){ leftServo.write(90 + speed); rightServo.write(90 + speed);}/* * sends the robot left */void goLeft(){ leftServo.write(90 - speed); rightServo.write(90 - speed);}/* * stops the robot */void goStop(){ leftServo.write(90); rightServo.write(90);} //END OF ARDUINO CONTROLLED SERVO ROBOT (SERB) ROUTINES//---------------------------------------------------------------------------

Step 7: Finished, Others Who Have Finished &amp; the Future

Congratulations on getting this far and I hope you're having fun with your Arduino Controlled Servo Robot - (SERB).

Michael Beck's SERB -Michael found the plans for the SERB over at and cut his out of yellow and red acrylic. I think it looks great.

Mike's SERB - Mike (of St. Louis Area robot club ROBOMO ) had a friend laser cut a SERB chassis, and used his own robotic know-how to get it up and running. I think it looks awesome done in blue. (check out his website for details on this as well as his other robots (here)

This section will have details on future developments and attachments (they will be featured here before they are properly documented). But i would also like to show off pictures of other peoples SERB's.

So if you've finished send me a private message with a photo and a few words (be it a description or a link to your website) and I'll add it here.

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