Method of Equivalent Inverse Solution of Multi-rigid-flexible Body Dynamics and Performance Optimization Synthesis of Waist Exoskeleton Robot

doi:10.3901/JME.2024.05.107

Abstract

Abstract: Given the importance of reducing the waist load for its disease prevention, a research prototype of a multi degree of freedom bionic waist unpowered exoskeleton robot with human biomechanical characteristics is established. Then, aiming at the effective realization of the bionic working mechanism of motion bearing capacity considering human-machine fusion, the research of system bionic comprehensive performance optimization and its method based on the inverse solution of multi rigid flexible body dynamics are deeply carried out. First, based on relevant data of in vitro biomechanical experimental, an equivalent multi-body mechanical model is constructed, and then a multi-rigid-flexible body forward dynamic model of human-machine wearable parallel system is established on the sagittal plane. Secondly, aiming at the effective realization of comprehensive research of performance optimization of waist exoskeleton robots, a new dynamic comprehensive performance evaluation index named bionic load-bearing comfort level is proposed. Once again, to solve the non-causal complexity of the frequency domain method for solving the flexible inverse dynamics, an equivalent method of iteratively approximating the inverse solution of multi-rigid-flexible body dynamics by positive dynamics linear optimization is proposed to achieve the consistency of the thoracic spine trajectory before and after the exoskeleton robot is worn. Finally, the bionic comprehensive performance optimization of the multi-rigid-flexible body system of the human-machine wearable parallel system is carried out in depth, and then the optimal design parameter set of exoskeleton robot is obtained. The simulation results show that before and after the exoskeleton robot is worn, under the condition that the trajectory error of the bending angle of the human thoracic vertebra in the sagittal plane is minimal (4.5×10^‒6(^o)), the equivalent force of the human body is significantly improved compared with those before wearing. The optimized exoskeleton wearing comfort index is significantly improved, which proves that the waist exoskeleton robot has better dynamic bionic comprehensive dynamic performance and the reasonable effectiveness of the research methods. At the same time, the optimized system design parameters are of great significance to the development of the physical prototype of the waist exoskeleton robot and the related experiments.

Key words: waist unpowered exoskeleton robots, multi rigid-flexible body, forward dynamics, equivalent inverse dynamics, bionic load-bearing comfort level, comprehensive performance optimization

CLC Number:

TH122

ZHOU Zuyi, YANG Yuwei, QI Wenyao, GONG Jianchao, LI Zhaotong. Method of Equivalent Inverse Solution of Multi-rigid-flexible Body Dynamics and Performance Optimization Synthesis of Waist Exoskeleton Robot[J]. Journal of Mechanical Engineering, 2024, 60(5): 107-118.

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