For working and manipulating heavy loads in unstructured environments combined legged and wheeled vehicles, often realized as walking excavators, can be used. The most evident advantage of legged machines against wheel-driven vehicles is their ability to move in unstructured terrain. Possible areas of applications for legged working platforms are outdoor tasks such as forestry or building avalanche protection. Smaller robots can be used for inspecting inaccessible, hazardous or contaminated areas. These machines consist of a platform with two front legs and two swivelling wheels at the back. They combine the advantages of a walking machine - mobility in unknown terrain - with the higher stability and velocity of wheeled vehicles. Here the forward movement is provided by driven rear wheels or through the use of a manipulator attached to the top of the vehicle (i.e. the excavator arm and bucket). A recent development in the field of walking excavators is the roboTRAC which has improved mobility in the front legs. ALDURO further refines this system.

In contrast to the existing machines mentioned above, the forward movement of ALDURO (Anthropomorphically Legged and wheeled Duisburg Robot) is generated by the co-ordinated motion of the legs. In one configuration it can be used as an quadruped walking machine (see figure at top) or, with two wheels instead of the rear feet, it can be used as a combined legged and wheeled vehicle. Systems of this size and weight can only be driven efficiently using hydraulic actuators. The actuators and transmission mechanisms create kinematic loops. The main characteristic of the mechanical setup, and its representation as a multibody system, is the closed kinematic loops, which are modelled with the multibody simulation library MOBILE.

The ALDURO is to be steered by a driver who sits a on top of the platform. He directs the system in cartesian coordinates with the help of a joystick. These commands are interpreted by a cental control computer that autonomously generates the walking patterns required to move the machine in the direction indicated (modular controller structure) .

The prototype has a length of 3.50m and a width of 2.40m, a mass of approximately 1800kg. The total mass of the system is high due to the high degree of autonomy required. The power needed to drive the hydraulic circuits and the energy for the control computers is produced by a modern combustion engine of approximately 40kW (a three cylinder turbo loaded benzin motor of the smart automobile) that is mounted on the rear of the platform. At the moment the hydraulic drive system, including the engine, constitutes about 40% of the total weight of the ALDURO.

The controller software runs on a Intel P3 700MHz cPCI System, on a Debian Linux System (Sarge) with RTAI-LXRT real-time extension. For implementation, the modular, network-transparent software framework MCA2 (open source, FZI Karlsruhe) is used. It allows for structuring (1, 2, 3, 4, 5) of the project and offers a graphical user interface to start/stop, operate and monitor the robot.