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Design, Analysis and Control of the Series-Parallel Hybrid RH5 Humanoid Robot

Julian Eßer; Shivesh Kumar; Heiner Peters; Vinzenz Bargsten; José de Gea Fernández; Carlos Mastalli; Olivier Stasse; Frank Kirchner
In: 2020 IEEE-RAS 20th International Conference on Humanoid Robots (Humanoids). IEEE-RAS International Conference on Humanoid Robots (Humanoids-2020), July 19-21, Munich/Virtual, Germany, Pages 400-407, IEEE, 7/2021.


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.