【摘要】 针对水下运动中蛙人下肢姿态与流场环境的动态耦合机制问题展开研究。首先,采用流固耦合仿真方法,构建穿戴式助力装备的蛙人下肢动力学数值模型,通过与实验结果进行对比,验证了数值模型的可靠性;其次,基于验证模型分析不同航速下水流冲击对蛙人下肢姿态的影响,揭示了关节角度变化规律;最后,基于NSGA-Ⅱ多目标优化算法得到不同航速时下肢关节角度的Pareto最优解集,提出了基于姿态补偿的阻力优化策略,并通过实验验证了优化效果。研究结果表明:固定航速下,下肢姿态经历“最大形变—反向调整—动态平衡”3个阶段,且随着运动速度提高,下肢稳定姿态更趋于流场自适应平衡点;在1～3 kn航速范围内,髋、膝、踝关节的姿态稳定角度与阻力最优角度之间的补偿量分别为-0.78°、2.28°和-1.05°,在对下肢姿态优化实验验证中,航速较自由状态提高9.09%,说明通过下肢姿态角度约束可以提高水下运动性能,为水下助力外骨骼关节模块的闭环控制和总体的流场适应性设计提供了量化依据。更多还原

【Abstract】 In this paper, the dynamic coupling mechanism between the posture of the lower limbs and the flow field environment in the underwater movement of frogmen was deeply studied. Firstly, by using the fluid-structure coupling simulation method, a numerical model of the frogman’s lower limb dynamics with wearable assistive equipment was constructed, and the reliability of the numerical model was verified by comparing the experimental results with the simulation data. Secondly, based on the validated model, the influence of water flow impact on the posture of the frogman’s lower limbs at different speeds was analyzed, and the rule of joint angles was revealed. Finally, the Pareto optimal solution set of lower limb joint angles at different speeds was obtained based on the NSGA-Ⅱ multi-objective optimization algorithm, and the drag optimization strategy based on attitude compensation was proposed. The optimization effect was verified through experiments.The results show that at a fixed speed, the lower limb posture experiences three phases: “ maximum deformation-reverse adjustment-dynamic equilibrium”. As the speed increases, the stable posture of the lower limb tends to approach the adaptive equilibrium point of the flow field. Within the 1～3 kn speed range, the compensation between the posture stabilization angle and the optimal angle of resistance for the hip, knee, and ankle joints is-0.78°, 2.28°, and-1.05°. In the experimental verification of lower limb posture optimization, the speed is increased by 9.09% compared with the free state. It is demonstrated that by constraining the posture angles of the lower limbs, the underwater movement performance can be improved. This provides a quantitative basis for the closed-loop control of the joint module of the underwater assisted exoskeleton and the overall design of the flow field adaptation.更多还原