More fun with robots

Szymon Kobalczyk — Mon, 06 Jul 2009 09:27:46 GMT

Last Friday I’ve received new Futaba S3001 servos. Turns out they are more easier to modify to Hitec’s, and at the same seem more reliable. I’ve simply followed this Instructable, and you can also find some additional photos in my gallery. What most important the servos are also easier to calibrate, so now my SERB will actually stop in place when I want it.

Below is a short video of the completed SERB robot where it just runs in random directions:

This weekend I’ve also started looking at Microsoft Robotics Development Studio 2008. This environment promises easy entry level to robotics. However this is true only when you have a compatible robotics platform (like Lego Mindstorms NXT, fishertechnik, iRobot and few others). There are pretty good tutorials on how to control these robots both from C# and from VPL. However before I can apply them to my SERB robot, first I need to implement the hardware interface and generic services to control the robot. Not much information on this and closest what I found so for is the Robotics Tutorial 6 – Remotely Connected Robots. It would be cool to get more detailed example on writing such services, but fortunately source code of services for other robots is included. In particular I’m trying to understand the code for iRobot and this additional service for VEX Robotics. If you know of any other good examples or tutorials please let me know.

Building Arduino Controlled Servo Robot (SERB)

Szymon Kobalczyk — Thu, 02 Jul 2009 07:05:25 GMT

Few weeks ego we went to an exhibition in one of Kraków’s malls to celebrate the 100 year anniversary of robotics. Besides some nice exhibits there was also a place where kids could try to build a robot from Lego Mindstorms NXT and Fishertechnik sets. We spent few hours there with my older son Jaś and even managed to build a walking robot.

It was fun for both of us so I started looking if we could continue playing with robots at home. Unfortunately most of the sets I found are pretty expensive (starting at $200). This is where my good pal Marcin Książek turned me to the Arduino electronic prototyping platform.

Arduino is really a simple and cheap microcontroller kit that can be easily connected to a PC and programmed. What makes it fun is that there are also many extensions that come as “shields” and adapters for the board and add capabilities such as XBee and Ethernet communication, accelerometer, DC motor control, GPS or even a touch LCD. The platform is open source so there are tons of information and fun projects on the web. Good place to start would be the Arduino Experimentation Kit (ARDX) – you can buy the kit from oomlout, but it’s also open source so you can download all guides and buy the parts in your local electronics store yourself. I also enjoy reading the book “Getting started with Arduino” by Massimo Banzi. And make sure to send the Arduino gift guide to your relatives. There are even Arduino user groups such as Howduino in Liverpool.

[In Poland you can buy Arduino from Nettigo]

All of this makes Arduino a great basis for building a simple robot. And in fact there is already a project on Instructables that shows exactly How to build a Arduino Controlled Servo Robot. Again this project is open source so you can buy a kit from oomlout or download the blueprints and find all the parts yourself. The body of the robot is done from acrylic sheets and I found a local shop with a laser cutter that could cut the parts for me. Most of the other parts can be easily found in your local DIY store.

One exception are the servo motors. Normal servos for RC models are constrained to movement in 180 degrees range, but what we need here is a “Continuous Rotation” servo. You can get one that was pre-modified such as Parallax, GWS S35 or Hitec HSR-1425CR. Another option is to modify the servo yourself, and there are also many instructions on how to do it on the web. I found that it’s really not hard to do, but you have to work a bit on the calibration.

So having all the parts I could finally begin the assembly. Below you can see is a photo gallery where we build our first SERB robot. As you can see I’m one happy geek dad, because both kids were pretty interested with this.

Right now the robot can’t do much besides running around in random directions, but I have some plans to make it smarter.

Add remote control via Xbox pad or WiiMote. There is already a project showing how to use a netbook to control the robot via Skype. But being a .NET geek I would like to use Microsoft Robotics Studio for this.
Add wireless connection with XBee so that robot can roam freely without cables the but still being controlled from the PC.
Add some sensors so the robot gets more information from the world. I think first I would add bumpers to detect obstacles as shown in this project. Later I might also add wheel encoders (such as Nubotics WheelWatcher) for odometry.
Play with some AI algorithms.

So it looks like I already have found myself a summer project :-)