Read this first: Interactive Skype-Controlled Mindstorms NXT Car (original post)
Some of you might have noticed that my Skype car has been offline since last night. Why, you wonder? I was trying to solve the issue with the wire tangling around the robot all the time – first, I tried putting it on a high pole, but that just made it worse. Then I remembered an amazing Mindstorms NXT robot I once read about: Pulito, a floor cleaning robot that could look for its own power source using infrared light, and then plug itself in.
Since I do not have any equipment to read infrared light, I had to find another way for the robot to plug in. Here’s what I did:
- Because the environment my robot was in was way more controllable (a square lined with cardboard boxes), I decided to use the sonar sensor, and make the robot follow the walls.
- I then made a gap in one part of the wall, so the robot wouldn’t know where the corner was. That causes it to just keep on driving forwards, until it hit the wall on the other side.
- This is where I got lucky: when I ordered the charger for my new battery, I got the wrong one (the one for the other kind of battery, which was hooked up to my other NXT). Having a spare one, I decided to cut it in half:
- So when the car hits the wall, it’ll automatically start charging
- For the programming, I added some code for the ultrasonic sensor and the touch sensors, and wrote some sequences to happen when the robot needs to start charging, and when it’s done.
- The instructions on the actual remote control page are much clearer now, too
- The robot is now back online.
To read more about my Skype car, click here.
Disclaimer: The Skype name, associated trade marks and logos, the Skype “Call Me” button and the “S” logo are trade marks of Skype.

[...] 1/6/2012: Took the robot offline for the night and better part of the day to solve an issue with the battery’s wire getting tangled and ripping the robot apart – went wireless. [...]