GPS on Wheels - A Robotics-Project at the IWR in Heidelberg

This winter term we're doing an interesting internship at our university: We're constructing a robotic RC-car, supplied with a Rasperry Pi-Computer and a GPS-module in order to be able to drive autonomously.
The internship started in October 2014 already and lasts until the end of March approximately.

The university

The internship takes place at the University of Heidelberg, located in a small, but famous and beautiful town in the south of Germany. The university can proudly call itself the oldest one in Germany.
Altough all of us are studying physics, the project is part of the IWR (interdisciplinary research center for scientific computing) at the Informatics Faculty, which illustrates the flexibility in our studies and also gives a hint of what we're mainly doing here: programming.
As we are not the only ones working in a robotic internship, here is a list of all current robotic-projects at the Robotics Lab.
Our project is supervised by Gero Plettenberg and Thomas Kloepfer Thank you guys, for your help!

The goals

The main goal is to construct and configure an autonomous RC-car, which should be able to reach a given GPS-Position somewhere nearby, avoiding small obstacles.
Thus it is part of the project to supply a RC-car with a small computer (Raspberry-Pi), a GPS-module and some sensors to detect obstacles. Of course, also the programming of the components -as they need to work together- makes a great part of it.
Some milestones can be summarized as follows:

• choosing appropriate components (RC-car construction-kit, batteries, motor, Raspberry Pi, ultra-sonic sensors, GPS-module, servos ...)
• constructing the RC-car out of the construction-kit, attach batteries, motor & cruise control
• modifying the car by attaching the Raspberry Pi, as well as the sensors & the GPS-module;
  herefore: adding a platform onto which the components can be put
• connecting all components in a safe way
• constructing some cover for the electronics to be safe from dirt, moisture etc.
• developing some algorithm of how everything works together
• programming a lot of routines for the different needs (getting GPS-position, calculating target-position & direction, getting sensor-data, recognizing obstacles, driving the car, avoiding obstacles, finding a good way, handling errors...)
• testing, impoving, testing, improving....

Besides these practicle things, of course it is a declared goal to improve our skills and to learn about informatics during this internship. Apart from programming (mainly python here), the project also involves a lot of (electronical) handicraft. We therefore get in touch with electric circuits, information processing, mechanics and the interplay of hard- and software.
As we will have to face many problems, we will have to learn to react and find solutions flexibly.

The resources & components

Except our knowledge, the ressources we are using are either provided by the informatics faculty (thanks, guys ;) ) or are open-source (source-code & information from the internet).
As there are many other groups working on different robotic-projects at the IWR, there is a small room available to all internship-students at the university, equipped with computers, internet and a lot of hardware-stuff (cables, connectors, electronic components, wood, metal, screws, ...). Also any tools needed, such as screw-drivers, drilling machines, saws, soldering irons, voltage and ampere meters, voltage suppliers and many more things, can be found and used there.

Besides some cables, switches, diodes, connectors, screws and plexiglas, the components we are using, are

• a RC-car construction-kit "Reely Blaze" from Conrad Electronics (image1, image2)
• a 7.2V 3700mAh NiMh rechargeable battery pack for RC-cars from Conrad Electronics for the motor and peripheral devices (image)
• a 9.6V 2300mAh NiMh rechargeable battery pack from Conrad Electronics only for the Raspberry's power supply (image)
• a speed control from Conrad Electronics to control the motor-speed (image)
• a 7.2V tuning-electromotor from Conrad Electronics (image1, image2)
• a steering-servo to control the direction of the car (image)
• a mini computer Raspberry Pi Model B+ (image1, image2)
• a 4GB micro SD-card (anyone like these)
  [Note: I suggest picking a bigger one than 4GB, we had some problems with the space during our work. 8GB is already fine.]
• three cheap ultrasonic-sensor (HC-SR04) (image)
• a servo to move one of the ultrasonic-sensor (image)
• a GPS-module (3DR GPS uBlox) from 3D Robotics (including an electronic compass) (image)
• a simple wireless-adapter from TP-Link for remote-ssh-control (AP-mode)
  [Note: this model is actually not the best choice to work with on a Raspi] (image) and
• a self-made 7V to 5V voltage-regulator (which seems to work fine with 9.6V, too) (image)

This page

On this cool github-webpage, made with jekyll, we want to tell anyone, who's interested, about our project. We try to keep it update and to provide detailed information about which problems we had to face and how we solved them. We hope we're helping you to solve your own problem in that way. ;)
Of course we add a lot of great pictures to our posts for them to become more clearly and interesting. Check out our Documentation-section to get more detailed information!
If you have any questions, do not hesitate to aks us!

Actually the project can be summarized shortly: