Darmstadt Dribblers 2004: Humanoid Robot

This paper describes the design and implementation of the first humanoid robot prototype of the Darmstadt Dribblers, which participated in the Humanoid League of RoboCup for the first time in 2004. The robot is used as a vehicle for research in control of locomotion and behavior of humanoid robots with many degrees of freedom and many actuated joints. For humanoid robots highly nonlinear physical dynamical effects must be considered on all levels of a reactive-deliberative control architecture realizing autonomous robot behaviour. The Humanoid League of RoboCup provides an ideal testbed as the problem of generating and maintaining statically or dynamically stable bipedal locomotion is predominant for all types of motions during a soccer game. The team has evolved from the Darmstadt Dribbling Dackels team which continuously has participated as part of the German Team in the Sony Four-Legged League since 2001. 1 RoboCup and the Dynamics of Robot Motion The RoboCup scenario of soccer playing legged robots represents an extraordinary challenge for the design, control and stability of bipedal and quadrupedal robots. In a game, fast motions must be planned autonomously and implemented online which preserve the robot’s stability and can be adapted in real-time to the quickly changing enviroment. Existing design and control strategies for humanoid robots can only meet these challenges to a small extent. During the nineties, both trajectory planning methods relying on nonlinear robot dynamics and model-based control methods have evolved into the state-of-the-art for developing and implementing fast and accurate motions for industrial manipulators. Successful control of the nonlinear robot dynamics is also the key to fast and stable motions of bipedal and quadrupedal robots. Many subproblems remain unsolved in fulfilling this objective. The purpose of the Darmstadt Dribblers is to contribute to this ambitious goal by discussing fundamental principles and recent methods in the modeling, simulation, optimization and control of legged robot dynamics. For wheeled robots in the Small and Midsize Leagues maintaining balance during locomotion is not a big issue. Thus, there is no need for using a kinetical model of wheel robot dynamics besides planning and implementing motions of high speed and high position accuracy. In the Four-Legged League mostly trot-like gaits on the elbows of the front legs are used. This results in a relatively low height of the center of mass above ground, and thus, maintaining balance is not too difficult. However, in the Humanoid League the problem of stability of legged locomotion cannot be avoided. 2 Technical Data of the Humanoid Robot Prototype The humanoid robot we use in RoboCup 2004 is depicted in Fig. 1 (as in February 2004). The robot is a unique prototype which has been custom-made for our purposes by iXs Research Corporation (http://www.ixs.co.jp).