The Research About Stress Characteristics Of Rape Seedlings Stems And Seedlingd-Fetching Mechanical

With the increasing of agricultural mechanization , agricultural machinery is widely used. The bowl of the rape seedlings are used more in the transplanting areas as its own unique advantages . How to fetch the bowl of rape seedlings and minimize the harm by the manipulators is a problem needed to be solved in the transplanting areas .The mechanical finger is designed according to the needs and physical characteristics of the objects fetched. The rape seedling stems are organisms, Their organizations are vulnerable damaged in large stress. This thesis introduces the gripper folder for fetching rape seedlings. If the clamping force is too large, it will directly undermine the organizations of the rape seedlings, and it will reduce the survival rate of nutritional bowl for rape seedlings. It will also cause huge losses in seedlings transplanting areas. So, it is necessary to study the mechanical properties of the rape seedling stems. It is easy to measure the limit stress of the rape seedling stems when using TA-XT2i texture analyzer. All of these were the foundation of end-effector's design .Mechanical hand is the key components which directly used to gasp the objects . To design for the hand structure, it should be according with the perspective of practical application . The author select the clamp and linkage-leverage paw because its structure is simple ,its reliability is high and it is also easy to control . Through analysising the transmission ratio and transmission efficiency , the paper revealed the transmission ratio between the driving force and the gripping power of the manipulator ,which supports the foundation for other structural parameters .In this thesis, the author designed mechanical structure of the hand for the manipulator ,and used PRO/ENGINEER to mold and assembly for the operating manipulator . According to the working principle and requirements of the mechanical finger , the thesis choose the mechanical drive system for the manipulator .The ball screw has its unique advantage ,for example, its friction loss is low, its movement is smooth , and its transmission is reversible ,but its efficiency is high , so it is widely used . The thesis choose a suitable ball screw from structure, main size, the axis-direction clearance ,the way of adjustment, and the support pattern . Play a good role for the ball screw and reduce the size of the equipment.Driving components is used as an impetus for the electrical and mechanical systems . Electric actuator is universal, easy-operated , easy connected with other control device , so it is widely used ,which also has the advantage of fast response , greater impetus and non-pullution . Stepmotor can be controlled directly by pulse signal , its error is little and will not cumulative . This thesis introduces types of the stepper motor , working principles and basic principles of choosing stepper motor : Basic parameters,characteristics,working principles,driving method and so on . The thesis also gives details of the calculation process .In order to study the work of mechanical finger , the hand was placed in a 5-DOF manipulator , a 5-DOF cartesian coordinate system for the manipulator was set up, then the positive kinematics and inverse kinematic equation was get. The thesis studies the answers of the positive kinematics and inverse kinematic equation . The thesis also support theoretical foundation for further study of the manipulator's kinetics and control.