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BIT’s progress in the field of dynamics of flexible multibody systems

News Resource: School of Aerospace Engineering

Editor: News Agency of BIT

Translator: Bo Yilin, News Agency of BIT

Recently, the space structure dynamics and control research team led by academician Hu Haiyan of BIT, has made breakthroughs in the fields of soft body robot dynamics, human multi-body dynamics, rope net capture dynamics, and multi-flexible body dynamics algorithms.

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Fig. 1 Soft gripper realizes fast spatial capture of concept map

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Fig. 2 Topological optimization of dielectric elastomer soft actuator electrode :(a) calculation results;  (b) Experimental results

Soft body robots are multi-flexible systems containing soft material components with high environmental adaptability and interaction safety. To address the problem of rapid assembly of space structures, the team, including Assistant Professor Luo Kai, proposed a fast capture scheme based on a bistable soft gripper (Figure 1), which can achieve adaptive adjustment of the capture of targets in different states by adjusting the energy potential of the steady-state leap. Further, an electrode topology optimization method for the soft actuator of dielectric elastomer is proposed for the dynamic design problem of the soft actuator (Figure 2). Two related papers were published in Soft Robotics, a top journal in robotics (Y. Liu, K. Luo* et al. DOI: 10.1089/soro.2021.0147, 2022; P. Zhang, Z. Yan, K. Luo*, Q. Tian*. (DOI: 10.1089/soro.2021.0169, 2022). This is the first time that the research results of School of Aerospace Engineering, BIT are published in this journal.

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Fig. 3  Personalized modeling and wide opening mouth simulation of oral-maxillary musculoskeletal system

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Fig. 4  Multi-body dynamics simulation and mixed motion capture experiment platform for human musculoskeletal system

The human musculoskeletal system is also a typical multi-flexible system, and its dynamics and control research is an emerging cross-fertilization field of dynamics and biomechanics. In the study of musculoskeletal system dynamics, team member Dr.Guo Jianqiao et al. proposed a personalized kinetic modeling method for human oromandibular system (Figure 3), and applied multi-body dynamics to the practice of oromandibular tumor surgery planning. The research results have been clinically applied in Peking University Dental Hospital and the related paper has been published in the Journal of Biomechanics (Dr. Guo Jianqiao et al. 139: 111143, 2022). Dr. Guo Jianqiao was also invited to publish a long review paper in Advances in Mechanics (Dr. Guo Jianqiao et al. 52(2): 1-58, 2022). In 2021, Dr. Guo Jianqiao was also invited to give a conference presentation at the first "Symposium on Sports Biomechanics and the Promotion of Sports Science and Technology" in China.

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Fig. 5  Space debris capture methods

The space debris problem is becoming more and more serious, and how to safely carry out debris deconvolution and capture is a difficult and hot research point. The use of space rope net and robotic arm to capture debris is a feasible capture method (Figure 5). For the space rope net capture method, a new model of the "service spacecraft-rope net-target" combined system dynamics was constructed based on the absolute node coordinate method of multi-flexible body dynamics by Assistant Professor Shan Minghe and other team members, and the capture dynamics of the system was predicted by combining experimental and computational ideas. For this kind of underdriven system, Shan Minghe et al. also proposed an algorithm for target deconvolution control based on the tether tension, constructed a contact dynamics model between the end-effector and the target, and successfully deconvolved the target debris using a hybrid force-position control method. The related papers have been published in Aerospace (M. Shan, L. Shi. 9: 33, 2022), Acta Astronautica (L. Shi, X. Xiao, M. Shan* et al. 193: 469-482, 2022). The research results have been applied to the design of rope net capture systems by our aerospace sector. In the research of multi-flexible body dynamics modeling, Associate Professor Han Shilei, a member of the team, proposed a series of new finite units for multi-flexible body dynamics analysis based on the principle of dyadic quaternion and variable domain Hamiltonian variation, which can realize efficient modeling and computation of the system. Also, the research results were published in the top journal of computational mechanics, Computer Methods in Applied Mechanics and Engineering (S. Han. 395: 115063, 2022), which was highly evaluated by peer experts. In addition, Wang Shuai, a PhD student of the team, proposed a solution for space debris removal and protection based on the assembly of cubic star clusters, which won the Grand Prize of the Space Universities CubeSat Challenge(SUCC) China Final (Figure 6).

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Fig. 6 Certificate of the Grand Prize of the Space Universities CubeSat Challenge(SUCC)China Final

Space Structure Dynamics and Control Laboratory of School of Aerospace Engineering, founded by Academician Hu Haiyan in 2009, has 3 professors, 1 associate professor, 2 assistant professors, and 3 postdocs. In 2016, Academician Hu Haiyan was invited to present the team's research results in dynamics of multi-flexible body systems at the 24th World Congress of Mechanists (Mechanics Olympics), and was highly evaluated by many international famous mechanics. In 2021, the team, Prof. Tian Qiang, was awarded the National Outstanding Young Scientists Fund project grant. Recently, Prof. Hu Haiyan was elected as a foreign member of the 195th Hungarian Academy of Sciences at its General Assembly, who was the only foreign member elected in the field of engineering science this time.