TubRob is a blimp filled with helium, 2.5 meters in diameter. It is propelled by six electric engines. Computational power is located both onboard (two microcontrollers) and on the ground (one PC and one microcontroller).  The blimp and the ground station communicate via a radio link. Further principal components are an ultrasonic positioning system, an ultrasonic altimeter, an electronic compass and the gripper for acquiring the disks. The highlights are presented in greater detail below.

Microcontrollers
The microcontroller boards have been developed in the TubRob project. Dieser Eigenbau ist speziell auf diese Aufgabe ausgerichtet: Er ist klein, leicht und besitzt viele Anschlußmöglichkeiten für Sensorik und Aktorik. 

Specifications: 

• Microcontroller chip SAB80C166 (Siemens AG)
• 16 bit, 20 MHz RISC CPU with fast interrupt processing
• 16 channel compare/capture unit
• 10 channel A/D converter @ 10 bit resolution
• 2 standard serial interfaces
• 256 Kbyte RAM
• 128 Kbyte ROM

Positioning System
A circular ultrasonic transmitter consisting of twelve ultrasonic transducers by Polaroid is located onboard. Eight receivers are positioned at the border line of the competition arena such that at least three of them will always receive a signal from the transmitter. Time-of-flight calculation gives circular base lines relative to each of the receivers. The blimp's position within the arena is determined through triangulation. The system is accurate to a few centimeters over the whole arena, which is 20 m times 40 m in size. 

Software
The four computers involved cooperate on the task of guiding the blimp according to the variety of sensor data. Every computer runs different specialized processes. A carefully tailored real time multi-tasking system takes care of invoking the respective routines in time and implements the communication among the processes and the computers. The majority of sensor data are generated onboard and are, therefore, processed at that place. Fuzzy controllers calculate suitable revolutions-per-minute figures for the engines and control their accomplishment. A primary task of the ground station is to provide a user interface for both visualizing the robot's state and allowing manual interference (e.g. take-off, emergeny landing, manual override of parts of the control hierarchy for test purposes). 
 

As early as April 1995, a TubRob prototype presented at the Berlin booth at the Hannover Industrial Fair attracted considerable attention.  The final version took the second place in the copetition in Juli 1995 in Atlanta, Georgia. Only Standford University came in ahead, while others, like MIT, were surpassed. Besides this measurable success, having been involved in such an extensive project - which actually succeeded - was a great and valuable experience to the contributers.

After the competition TubRob was shown at the exhibition on the occasion of TU Berlin's 50th anniversary and at the "Feast of Ideas" (Fest der Ideen) initiated in September 1997 by the President of the Federal Republic of Germany.
 

• TU intern - TUBROB: Ein Roboter hebt ab und greift auf (in German)
• TU Media Information Nr. 146, 6. Oktober 1995 (in German)
• Homepage of the International Aerial Robotics Competition (IARC).

For more information, feel free to contact Wolfgang Brandenburg or Marek Musial.