This article describes the government experimental program PRIMUS (PRogram of Intelligent Mobile Unmanned Systems) and the achieved results of phase C demonstrated in summer 1999 on a military prooving ground. In this program there shall be shown the autonomous driving on an unmanned robot in open terrain. The most possible degree of autonomy shall be reached with today's technology to get a platform for different missions. The goal is to release the soldier from high dangerous tasks, to increase the performance and to come to a reduction of personnel and costs with unmanned systems. In phase C of the program two small tracked vehicles (Digitized Wiesel 2, airtransportable by CH53) are used. One as a robot vehicle the other as a command & control system. The Wiesel 2 is configured as a drive by wire-system and therefore well suited for the adaption of control computers. The autonomous detection and avoidance of obstacles in unknown, not cooperative environment is the main task. For navigation and orientation a sensor package is integrated. To detect obstacles the scene in the driving corridor of the robot is scanned 4 times per second by a 3D- Range image camera (LADAR). The measured 3D-range image is converted into a 2D-obstacle map and used as input for calculation of an obstacle free path. The combination of local navigation (obstacle avoidance) and global navigation leads to a collission free driving in open terrain to a predefined goal point with a velocity of up to 25km/h. A contour tracker with a TV-camera as sensor is also implemented which allows to follow contours (e.g. edge of a meadow) or to drive on paved or unpaved roads with a velocity up to 50km/h. In addition to these autonomous driving modes the operator in the command & control station can drive the robot by remote control. All the functions were successfully demonstrated in the summer 1999 on a military prooving ground. During a mission example the robot vehicle covered a distance of several kilometers in open terrain and on unpaved roads and performed a reconnaissance operation with the built-in RSTA- sensors. PRIMUS-C meets the requirements to drive autonomously and teleoperated in open terrain and on roads. The realized functions can be transfered to any vehicle and adapted to different mission requirements. This means that PRIMUS-C is a universal, modular and vehicle-independent platform for different military applications.