CONTROL OF A BIO-INSPIRED FOUR-LEGGED ROBOT FOR EXPLORATION OF UNEVEN TERRAIN Dirk Spenneberg 1 , Stefan Bosse 2 , Jens Hilljegerdes 2 , Frank Kirchner 1,2 , Andreas Strack 2 , and Heiko Zschenker 2 (1) DFKI Robotics Lab Robert-Hooke-Str. 5, D-28359 Bremen, Germany (2) University of Bremen, Robotics Lab Faculty of Mathematics and Computer Science Robert-Hooke- Str. 5, D-28359 Bremen, Germany dirk.spenneberg@dfki.de Abstract This paper describes the four-legged ARAMIES robot which was built on the experiences gained with a first integration study. It describes the revised mechanics. The new modular electronics low-level control concept is presented and the developed FPGA-based joint control is explained in detail. Furthermore an overview on the software control approach is given and the new ground contact detection module using an IR-sensor is explained. 1. INTRODUCTION The ARAMIES project deals with developing a walking robot which is capable of autonomous operation in extremely difficult environments, especially very uneven and steep terrain, e.g., the slopes of Martian / Moon canyons or craters. These sites are of high scientific interest. It is expected that in-situ measurements in the different layers of sediments would give new insights for the exobiology and exogeology. Furthermore it is likely to find frozen water in craters near the pole. For example, in February 2005 the HRSC on ESA’s Mars Express obtained a picture during orbit 1343, which shows an impact crater located on the Vastitas Borealis plain at approximately 70.5 North and 103 East, which at the centre contains residual water ice. The problem with craters is that they are extremely difficult to access for in-depth scientific studies. Conventional wheeled rovers are not able to provide this access reliably. Therefore we started to build the ARAMIES robot. A first integration study has been build and tested in 2005 [2]. Based on the results of these tests, a first full robot system (see fig. 1) has been built which features actuated claws, an additional hip joint, a fully integrated head segment, and a custom designed body. In the following, we present the improved mechanics, the new electronics concept for low-level joint control and further improvements in the software control, namely the ground contact detection, which is crucial for stable walking on uneven ground and a general problem for walking robots. In particular, we address a novel ground contact detection using a very simple infrared distance sensor. For the overall locomotion control we are using the bio-inspired PCR-control approach [5] which was already successfully implemented on the SCORPION robot [8]. 2. MECHANICS OF THE ARAMIES ROBOT The ARAMIES robot was build based on the integration study presented at the iSAIRAS 2005 [7] and at the CLAWAR 2005 [2] The main improvements in the mechanics are: In Proceedings of the 9th ESA Workshop on Advanced Space Technologies for Robotics and Automation 'ASTRA 2006' ESTEC, Noordwijk, The Netherlands, November 28-30, 2006