|Place of Conferral||北京|
|Keyword||仿生机器人 机器水母 连杆机构 重心调节 增强学习 仿真分析 水 下实验|
第二，基于ARM Cortex M4主控芯片，构建了嵌入式的闭环控制系统。利用定时器的PWM模式产生四路舵机控制信号以及三路步进电机控制信号，通过调整PWM波的占空比实现对数字舵机转动频率与幅值的控制以及对步进电机转动速度的控制。机器水母通过串口收发指令与数据，通过射频模块实现指令与数据的无线传输，由此将上位机与下位机连成一体，构成闭环控制系统。
|Other Abstract||Through millions of years of natural selection, aquatic animals have evolved extraordinary underwater motion capacity. Therefore, based on the principle of bionics and imitating marine life excellent flexibility and concealment, researches on underwater bionic robots have important theoretical significance and practical value.|
Inspired by the characteristics of freedom and flexibility as well as unique jet propulsion mode of live jellyfish, a novel biomimetic robotic jellyfish based on multi-linkage propulsive mechanism and barycenter adjustment mechanism is developed. The mechanical structure and the control system of the robotic jellyfish are detailedly designed and studied. An attitude control method based on barycenter adjustment and reinforcement learning control is developed. The main research achievements of this thesis are as follows.
First, based on the characteristics of the jet propulsion mode and the flexible change of attitude of natural jellyfish, a novel biomimetic robotic jellyfish equipped with the multi-linkage mechanism and barycenter adjustment mechanism is designed. In order to realize the simulation of the contraction-relaxation jet propulsion process of the real jellyfish, the limb linkage is driven by digital steering engine to achieve periodic reciprocating motion; barycenter adjustment mechanism completes regulating the center of gravity of the robotic jellyfish by coordinated movement of the two clump weights in horizontal and vertical directions, which make the posture of robotic jellyfish change. Waterproof sealing design includes static sealing and dynamic sealing.
Second, based on an ARM Cotex M4 main controller chip, an embedded closed loop control system is built. Digital servo and step motor control signals are generated from the controller by PWM mode of the Timer. Adjusting the duty ratio of PWM waves realizes control of the position and the rotation frequency of the digital servo and control of stepper motor rotation speed. The robotic jellyfish receives and sends commands and data from and to the upper controller through serial ports. The robotic jellyfish achieves wireless signal communication through the radio frequency module, which make the host computer and the slave machine a whole, thus a closed-loop control system is established.
Third, the attitude control method of robotic jellyfish based on the machine learning algorithm is put forward, which realizes the attitude control and stabilization of the robotic jellyfish through its own learning. Because the attitude control is a strong coupling and nonlinear problem with the regulation of the center of gravity, the reinforcement learning algorithm is used. The method transforms the robotic jellyfish attitude control model to an agent-environment model. Through the calculation of action weight, status weight and the reward function, as well as the relationship between the reward function value and the next action, robotic jellyfish attitude control on its own with reinforcement learning is achieved.
Fourth, the kinematic and dynamic models of the jet propulsion motion of the robotic jellyfish, and the dynamic model of the regulation process of the center of gravity are established. The simulation experiments and analysis for above three models can be drawn that the designed robotic jellyfish can realize contraction and relaxation jet propulsion mode to imitate true jellyfish; the movement trajectory of the robotic jellyfish completely encases the buoyancy center, which means control of 3D pose can be achieved. Furthermore, the reinforcement learning control system is convergence, which means the robotic jellyfish can reach the target attitude in a finite number of actions.
Fifth, the characteristics of underwater motion and attitude control ability of the novel robotic jellyfish are verified. Based on the coordination control of propulsion system and the barycenter adjustment system, a series of underwater motion control experiments for prototype of the robotic jellyfish are conducted. The robotic jellyfish can achieve unidirectional movement in any direction and composite motion. Through the analysis of the sensor data, the robotic jellyfish can reach the target attitude accurately and fast through Q learning control algorithm, which verify the feasibility of mechanical structure and motion control design of this novel bionic robotic jellyfish.
|First Author Affilication||Institute of Automation, Chinese Academy of Sciences|
|栗向滨. 基于重心调节与增强学习的新型仿生机器水母的研究[D]. 北京. 中国科学院大学,2016.|
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