| The active control of oral capsule robot not only solves the problem of visual blind spotin the process of clinical intervention,but also can control the movement of capsule robot through external magnetic field,which realizes safe and reliable detection of non-structural environment such as human gastrointestinal tract.It has a wide range of clinical application value,and also today's international micro-robot research hot spots.The main research contents of this paper are to analyze and study the dynamic characteristics of the capsule robot by simulation and experiment on the basis of the designed dual hemisphere robot.On the basis of summarizing the structural characteristics of existing capsule robots and the research of the research group,a structure scheme of dual hemispherical robot is proposed.The structure is mainly composed of two hemispheres that can rotate with each other.The coupling between the permanent magnet of the dual hemisphere robot and the space universal rotating magnetic field is realized,and the robot is moved in the active mode and the hovering in the passive mode.In order to study the working principle of the robot under the action of magnetic moment,the working mode of the robot is divided into three parts,active mode,passive mode and pseudo-passive mode,and modes can be conversed by changing direction of the magnetic field.No matter which mode the robot is in,the active hemisphere of the robot is always rotated relative to the axis,which is a dynamic problem.In order to analyze the modal dynamics,the spatial position and attitude of the robot are described by introducing the fixed coordinate system,the translation coordinate system and the Résal coordinates.Based on the Euler coordinate transformation,the gyroscope mechanics,the theoretical mechanics,the Lagrangian equation,robot modal dynamics equations are derivated.Because the dual hemispherical robot system is a kind of underactuated,time-varying,highly nonlinear,strong coupling system,the dynamic solution is complicated.In this paper,the dynamic equations of each mode are simulated by Matlab/Simulink module.Finally,the feasibility of the structure and the correctness of the multi-model theory were verified by the experiments of isolated pig colon.By analyzing the time response curve of the attitude angle of the robot axis,it is proved that the robot has strong anti-interference ability in the passive mode,and there is a certain stability interval between the magnetic field intensity and the magnetic field rotation angular velocity in the passive mode of the robot.With the direction of a certain magnetic field,the robot has a certain self-standing characteristic,which means thatno matter which mode robot is in,the robot can always be stable in the passive mode.This character ensures the uniqueness of the robot's axis direction and paves the way for the diagnosis of robots in the blind spot. |
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