Design And Analyse On Underwater Distance Variable Underactuated Robotic Hand

The technological advancement of modern society and the rapid increase in population have led to the overdevelopment of livable regions on lands,and the resources that are available to humans have become less and less;but the ocean,as a vast area that humans have not stepped into since ancient times,still contains a considerable amount of various types of abundant resources,it has increasingly attracted the attention of many researchers.At the same time,underwater mechanical hands,which can play a variety of roles in many underwater scientific researches,have became a recent research hotspot.The traditional underwater manipulators are mostly designed in simple gripper structures,which can only grip objects with a relatively single diameter and have poor adaptability to objects of different shapes,making it difficult to meet the requirements of reliability.Therefore in this thesis we designs an underactuated hand that can passively adapt to the shape of the target object to solve the above-mentioned problems.The thesis firstly carried out the design of the manipulator structure scheme and the optimization of its structural layout parameters.According to the task requirements of the manipulator and the attribute of the targeted object,with grasping force,feasibility and the waterproof design are all considered together,two possible design schemes are given to the palm and fingers of the manipulator respectively,and the scheme of synchronous belt transmission palm and underactuated finger linkage mechanism was designed.Then,aim at the finger gripping motion of the manipulator,a comprehensive grasping quality evaluation index which takes both grasping shape and grasping force into consideration was proposed,and it was used as an optimization index to optimize the size of the finger linkages and the structure layout parameter to ensure the gripping quality in this mission.In order to obtain the dynamic characteristics of the manipulator to improve the control performance,the finger linkage mechanism was further modeled and analyzed.First,the transformation matrix between the finger's working space,the contact coordinate system of the object and the fixed earth coordinate system is solved by the D-H joint method.Afterwards,the corresponding static analysis of the manipulator is carried out by using the obtained contact coordinates,and the stall torque required by the manipulator motor under the stable gripping state is caculated.The exponential vector method is used to solve the change of the kinematic parameters of the finger during the movement.Then,using the results of kinematic analysis,the forward and inverse dynamics analyses of the finger was carried out,and the rated torque required by the drive motor are obtained.And the forward dynamic equation of the finger.The error analysis of the model that does not consider the thickness of the finger bar is carried out,and the working error between the ideal state and the actual state of the manipulator is obtained.Based on the structural design scheme of the manipulator,the mechanical structural design of the manipulator is carried out.With reference to the analysis results of the manipulator's statics and dynamics,two suitable bus steering gears were selected for the manipulator;furthermore,a waterproof design was designed for the driving devices for the motor.Based on the design of actuating devices,the palm unfolding module and the robot finger grab module is designed in detail,and the iterative optimization of the mechanical structure is carried out in Ansys.Finally,a reasonable design of the manipulator's mechanical structure that meets the needs of task is obtained.Based on the dynamic model of the manipulator,facing the underwater working conditions of the manipulator,firstly,Ansys Fluent was used to simulate the corresponding water resistance coefficient,and then the obtained water resistance coefficient was brought into the Sinspace model,and have got the influence of the underwater environment on the manipulator during the capturing process.After that,under the guidance of PID control principles,Adams and Simulink were used to complete the control simulation of the finger capturing process.Finally,through the traversal simulation method,the feasible gripping areas of the objects with different diameters are obtained,and the corresponding grabbing strategy framework is formulated.Developed a prototype of an under-actuated manipulator for a large feasible underwater capture area,have its kinematics and dynamics analyzed,completed the underwater simulation of the manipulator's working process,and obtained the stable capture interval of the manipulator,finally formulated a framework for catching strategy.