The SmartTer - a Vehicle for Fully Autonomous Navigationand Mapping in Outdoor Environments Pierre Lamon, Sascha Kolski, Roland Siegwart Swiss Federal Institute of Technology Z¨ urich Autonomous Systems Lab, 1100 Z¨ urich email: pierre.lamon@a3.epfl.ch, skolski@ethz.ch, rsiegwart@ethz.ch Abstract — The driving factor for the development of the vehicle presented in this paper was to construct a hardware platform that allows to perform the tasks of en- vironment mapping and autonomous navigation in large scale outdoor environments. Our robot is based on a standard Smart car that has been equipped with five distance laser sensors, three cameras, a differential GPS, an Inertial Measurement Unit (IMU), an optical gyro- scope and four computers. The car’s systems states are directly accessed through the vehicle’s CAN bus. Local- ization and Navigation are realized by fusing all avail- able sensory information in a probabilistic way. This allows for high precision localization and dynamic local and global path planning. Using the 3D point clouds ex- tracted from the rotating lasers and the omnidirectional image the smartTer is able to consistently register the 3D maps and analyse the scene for regions of interest. To control the car in both longitudinal and lateral di- rection we applied a couple of modifications to the car, namely providing access to the car’s power steering sys- tem, electronic gas and brake pedal. Keywords — sensor fusion, outdoor vehicle, 3D mapping I. Introduction T HE main objective of this work was to construct a hardware platform that allows to perform the tasks of environment mapping and autonomous navi- gation in large scale outdoor environments. Nowadays, no commercial plateform is available for that kind of application and we had to develop a custom made ve- hicle. In order to avoid to start the design from scratch and to reduce the costs, a standard car was selected and modified in such a way that all the necessary char- acteristics for autonomous navigation and mapping are included. Substantial work has been done to accommo- date an additional power generator and to enable the car with ”drive by wire” capability. Moreover, the car was equipped with five distance laser sensors, two cam- eras, an omnidirectional camera, a differential GPS, an Inertial Measurement Unit (IMU), an optical gyroscope and four computer racks. Using the 3D point clouds extracted from the rotat- ing lasers and the omnidirectional images, the vehicle is able to consistently register the 3D maps and anal- yse the scene for regions of interest. The localization is realized by fusing data from the GPS, the IMU, the op- tical gyroscope and the car in a probabilistic way. This leads to an accurate and robust pose estimation that is used for autonomous navigation and to facilitate 3D scan matching. This paper is structured as follows. Section II de- scribes the modifications that were performed on the vehicle and the sensors chosen for perception. The au- tonomous operation and mission concepts are presented in section III. In particular, we present several results about vehicle localization and autonomous planning. Finally, section IV concludes the paper. II. Vehicle description Our vehicle, called SmartTer (Smart all Terrain), is a standard Smart car that has been enhanced for fully autonomous driving in somewhat flat outdoor environ- ments. The model is a Smart fortwo coup´ e passion of year 2005, which is equipped with a 45 kW engine. This model has been chosen because it gathers several advan- tages: • compact and light. Thus, the vehicle can be easily transported on a trailer to the testing area 1 and fits in our lab’s mechanical workshop. Furthermore, its light weight allows for fair locomotion performance in rough terrain. • power steering. The power steering motor has enough torque to steer the car. So, it is possible to ”steer by wire” with minor modification • auto gearshift. No additional modification is required to switch gears while the car is driving. • easy access to the CAN bus. Important sensory in- formation such as steering wheel angle and wheels ve- locities are thus directly accessible. All these features facilitate the process of convert- ing such a vehicle for autonomous driving. The fully equipped SmartTer is depicted in Fig. 1 and 2. A. Vehicle modifications In order to enhance the original model for au- tonomous driving, several modifications have been per- formed on the car. This section describes the mechani- cal and electrical changes that were necessary. • Wheels with better grip and larger diameter have been mounted. This allows for slightly higher ground clearance and much better traction in rough terrain. • A 24V power generator has been installed in order to power all the electronic devices and additional actua- tors. The generator is driven by a belt and pulley that is directly connected to the engine output axis (which is situated under the trunk, at the rear of the car). Two batteries placed in the trunk act as an energy buffer. They have a total capacity of 48Ah and are continu- ously recharged when the engine is running. • The power steering system applies a torque M add on the steering column that allows to minimize the effort 1 Because the car has been deeply modified, we are not allowed to drive in the traffic.