Feb. 26, 2015 | By Alec

That 3D printing technology is perfect for making RC racing cars is hardly a secret, and in recent months we’ve been seeing plenty of cool designs for extremely fun and equally fast 3D printed RC cars that are just begging to be copied. If you’re of that inclination, then head over to the Open RC project for more information on how to get started.

But what’s cooler: an RC car or an autonomous 3D printed driving robot? After seeing the cool project by theophil over at letsmakerobots.com, I’m inclined to chose the latter option. What he has essentially done is rebuild the ever-popular Dagu Rover 5 to function as an autonomous robot with awesome offroad wheels. While still a work-in-progress, it can already navigate its way around a room using a series of simple sensors.

As theophil explains in his blog post, he has been working on this project since November. ‘I wanted to start with a "simple" remote-controlled vehicle before making it autonomous. This should be a robot, after all,’ he writes. The Rover 5 by Dagu Electronics is perfectly suited for the task, being a durable and versatile robot platform for all terrains. ‘ll you need to get the car moving is a robot controller or motor controller to drive the two built-in DC motors, which powered by the included 6-AA battery holder, though to make it autonomous you’ll also need an Arduino Mega, a Readbearlab BLE Shield to send the sensor data, 3 SR04 sonar sensors and a Pololu MinIMU 9 compass, gyro and magnetometer.

All this is mounted on a series of 3D printed components that have been made with a PrintrBot Simple Metal 3D printer. ‘As many people have noticed before me, the axis adaptors for the Pololu offroad wheels are very long. The Dagu Rover chassis isn't very stable to begin with but with the wheels mounted at several cm distance, I was afraid the axes would break at any moment,’ theophil writes, so he also designed some new adaptors. ‘The process took a bit of trial and error but I like the result. I also like the holder for the gyro unit which creates a bit of distance between the magnetic fields created by the motors and the magnetometer.’

Truth be told, the software portion of this autonomous robot can be a bit complicated for the uninitiated, but theophil himself is a computer scientist who programmed everything himself through a trial an error method, though not without speedbumps. ‘I'm using the ArduinoPID library to control all four motors so that the wheels turn at the desired speed. The four motors on my Rover behave very differently. To drive at the same speed, the weakest motor needs a 20% higher PWM signal than the strongest motor. The difference is even larger when turning on the spot and some wheels must turn backwards,’ He laments.

Especially difficult was getting the sensors and compass to function as they should, but as they were the cheapest he could find it is far from perfect. ‘The robot sends its heading, the distance recorded by the wheel encoders and the sonar measurement via Bluetooth to my Mac,’ he explains. ‘My central command application is not only the remote control but is also supposed to become the robot's brain. It currently draws the robot's path and builds a map of the robot's surroundings based on the sonar measurements.’

For now, however, the results have been ambiguous; ‘you can only build pretty rough probabilistic maps,’ he says. As you can see below, the robot has so far been able to make some rough measurements of the obstacles in theophil’s living room.

While still very much a work in progress, it is nonetheless very cool to see that a few basic parts can be thrown together like that to form an (almost) autonomous robot. If you’d like to recreate this project, you can download all models and code for this 3D printed robot on Github here. While not quite perfect, future plans to include a Raspberry Pi 2 to make the robot truly independent are already in the works, so keep an eye open for theophil’s progress.

Posted in 3D Printing Applications

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