Wang Gengxiang, Bickerdike Andrew, Liu Yang, Ferreira Antoine
Exeter Small-Scale Robotics Laboratory, Engineering Department, University of Exeter, Exeter, EX4 4QF UK.
School of Mechanical and Electrical Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055 Shaanxi China.
Nonlinear Dyn. 2025;113(3):2091-2109. doi: 10.1007/s11071-024-10318-2. Epub 2024 Oct 14.
This study develops a dynamics model of a microrobot vibrating in a blood vessel aiming to detect potential cancer metastasis. We derive an analytical solution for microrobot's motion, considering interactions with the vessel walls modelled by a linear spring-dashpot and a constant damping value for blood viscosity. The model facilitates instantaneous state transitions of the microrobot, such as contact with the vessel wall and free motion within the fluid. Amplitudes and phase angles from the transient solutions of dynamics model of the microrobot are solved at arbitrary moments, providing insights into its transient dynamics. The analytical solution of the proposed system is validated by experimental data, serving as a benchmark to examine the influence of pertinent parameters on microrobot's dynamic response. It is found that the contact force transmitted to the vessel wall, assessed by system's transmissibility function dependent on damping and frequency ratios, decreases with increasing damping ratio and intensifies when the frequency ratio is below . At the frequency ratio is equal to 1, resonance phenomenon is dominated by the magnification factor linked to the damping ratio, increasing the amplitude of resonance as damping decreases. Finally, different sets of system parameters, including excitation frequency and magnitude, fluid damping, vessel wall's stiffness and damping, reveal multi-periodic motions and fake collision of the microrobot with the vessel wall. Simulation results imply that these phenomena are minimally affected by vessel wall's stiffness but are significantly influenced by other parameters, such as fluid damping coefficient and damping coefficient of the blood vessel wall. This research provides a robust theoretical foundation for developing control strategies for microrobots aimed at detecting cancer metastasis.
本研究建立了一个在血管中振动的微型机器人动力学模型，旨在检测潜在的癌症转移。我们推导了微型机器人运动的解析解，考虑了与血管壁的相互作用，血管壁由线性弹簧 - 阻尼器建模，并考虑了血液粘度的恒定阻尼值。该模型有助于微型机器人的瞬时状态转换，例如与血管壁的接触以及在流体中的自由运动。在任意时刻求解微型机器人动力学模型瞬态解的振幅和相位角，从而深入了解其瞬态动力学。所提出系统的解析解通过实验数据进行了验证，作为检验相关参数对微型机器人动态响应影响的基准。研究发现，通过依赖于阻尼和频率比的系统传递函数评估的传递到血管壁的接触力，随着阻尼比的增加而减小，并且当频率比低于 时会增强。当频率比等于 1 时，共振现象由与阻尼比相关的放大因子主导，随着阻尼减小，共振振幅增加。最后，不同的系统参数集，包括激励频率和幅度、流体阻尼、血管壁的刚度和阻尼，揭示了微型机器人与血管壁的多周期运动和假碰撞。仿真结果表明，这些现象受血管壁刚度的影响最小，但受其他参数的显著影响，如流体阻尼系数和血管壁的阻尼系数。这项研究为开发旨在检测癌症转移的微型机器人控制策略提供了坚实的理论基础。
