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胶囊机器人转弯动力学特性研究

Research on Capsule Robot Veering Dynamic Behavior

【作者】 王楠

【导师】 张永顺;

【作者基本信息】 大连理工大学 , 机械电子工程, 2010, 硕士

【摘要】 口服胶囊内窥镜的主动驱动与控制已成为微创或无创诊疗技术的一个研究热点和前沿,可减少诊疗周期和病人的痛苦。胶囊内窥镜在体内姿态的主动调整和行走的主动控制可以解决介入诊断的视觉盲区这一难题,因此对临床诊断技术意义重大。在先前的研究基础上,提出利用空间万向旋转磁场驱动与控制机器人在充满黏性液体的弯管内非接触地转弯行走,以及一种离散逼近的磁场控制策略,并建立机器人的转弯动力学方程。旨在通过对机器人在弯管内转弯运动的分析,为最佳的磁场控制参数的选择提供理论依据,达到实现机器人稳定地主动转弯行走的目的。提出新一代胶囊机器人并对其结构进行了描述。首先对空间万向旋转磁场的产生和机器人的转弯驱动原理进行了阐述。空间旋转磁场对机器人内驱动器的磁耦合作用形成磁驱动力矩,如果磁场的旋转轴与机器人回转对称轴不平行,则该磁驱动力矩在垂直于回转对称轴的方向上产生分量,该分量驱动机器人转动。给出非定常运动的Reynolds方程,并采用有限差分法和螺旋肋阶梯边界处流量控制对Reynolds方程进行数值求解,解决了复杂动压膜间隙函数引起的Reynolds方程无法直接求解得的难题。由于空间旋转磁场发生装置的线圈感抗引起的响应延迟,决定了空间磁场的旋转方向不能连续改变,因此本文提出离散改变磁场旋转方向的控制策略,控制机器人的行走路径逼近于弯管的中径曲线。在此控制策略的基础上,引入描述机器人空间姿态的赖柴坐标系。根据空间磁矢量耦合理论,建立了在机器人任意空间姿态下空间旋转磁场作用于内驱动器的磁驱动力矩模型。垂直于机器人回转对称轴的磁驱动力矩分量诱导机器人转向的同时伴随着摆动,管内运动流体形成的流体动压膜对机器人的摆动和空间姿态的变化分别产生阻尼作用和刚性阻抗作用。结合这两种作用建立了流体动压膜作用于机器人的流体力矩模型。结合前面建立的力矩模型,根据陀螺力学和定点运动的欧拉力学方程推导出了胶囊机器人的转弯动力学方程。使用MATLAB软件的Simulink工具箱编程求解动力学方程,对机器人的运动进行了仿真和分析。通过分析力矩的响应曲线,证明了机器人的随动效应;分析讨论了磁场控制参数对机器人转弯运动的影响。

【Abstract】 Active drive and control of oral capsule robot, which can reduce diagnosis and healing time and alleviate patient’s suffering, is becoming a research hotspot and leading edge in minimally invasive or noninvasive treatment both at home and abroad.Based on previous research, this paper proposed the utilize of space universal rotating magnetic field (SURMF) to drive and control robot non-contact steering in curved pipe filled with viscous fluid. A magnetic field control strategy of discrete approximation is proposed and steering kinetic equations are established, aiming at providing theory basis for selecting optimal magnetic parameters by analyzing robot’s kinetic motion to realize its active steady steering.A new capsule robot is proposed and its structure is presented in this paper. Firstly, the principles of SURMF generation and robot’s steering drive are elaborated. When rotating axis of SURMF is not parallel to that of robot, magnetic driving moment component, produced by SURMF coupling with robot’s inner actuator, emerges in the direction perpendicular to robot’s rotating axis, which drive robot to turn.In this paper non-stationary motion Reynolds equation is given, and the finite difference method and flow control at the side of spiral ribs are used to solve Reynolds equation, the later solve the problem that Reynolds equation with complicated thickness function of hydrodynamic film can’t be directly solved.As a result of operating lag caused by coil inductive impedance of SURMF generating device, which determined the rotating direction of SURMF can’t be continuously changed, a discrete control strategy is proposed to control robot’s walk path so that to be approximated to pipe’s diametral curve. Based on the control strategy, Resal coordinate system is introduced to determine robot’s posture.On the basis of coupling theory of space magnetic vectors, model of magnetic driving moment acting on robot in any posture by SURMF coupling with inner actuator is established, and whose component that perpendicular to robot’s rotating axis induces robot to turn and swing. Robot’s pose and kinetic motion influence on the moving fluid in pipe. The hydrodynamic film formed by flow in pipe respectively creates damping effect and resistant effect in response to robot’s swig and change of its pose. Based on the both effects, model of fluid moment acting on robot by hydrodynamic film is established.On the basis of gyrodynamics and Euler dynamic equations of robot rotating about a fixed point, and combining with the moment models mentioned above, robot steering kinetic equations are derived. Robot kinetic equations are solved with the use of Simulink toolbox provided by MATLAB, and robot kinetic motion is simulated and analyzed. Follow-up effect of robot is proved in analyzing the moment’s response curve. Influence of magnetic field control parameters on robot steering motion is analyzed and discussed.

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