Design, analysis and control of the series-parallel hybrid RH5 humanoid robot

• Main Authors: Esser, Julian, Kumar, Shivesh, Peters, Heiner, Bargsten, Vinzenz, Fernandez, Jose de Gea, Mastalli, Carlos, Stasse, Olivier, Kirchner, Frank
• Format: Journal Article
• Language: English
• Published: 26.01.2021
• Subjects: Computer Science - Robotics
• DOI: 10.48550/arxiv.2101.10591

Last decades of humanoid research has shown that humanoids developed for high dynamic performance require a stiff structure and optimal distribution of mass--inertial properties. Humanoid robots built with a purely tree type architecture tend to be bulky and usually suffer from velocity and force/torque limitations. This paper presents a novel series-parallel hybrid humanoid called RH5 which is 2 m tall and weighs only 62.5 kg capable of performing heavy-duty dynamic tasks with 5 kg payloads in each hand. The analysis and control of this humanoid is performed with whole-body trajectory optimization technique based on differential dynamic programming (DDP). Additionally, we present an improved contact stability soft-constrained DDP algorithm which is able to generate physically consistent walking trajectories for the humanoid that can be tracked via a simple PD position control in a physics simulator. Finally, we showcase preliminary experimental results on the RH5 humanoid robot.