Research On Underactuated Hand Based On Metamorphosis Principle And Analysis Of Dynamic Characteristics

With the popularization of robotics in industrial production,aerospace,national defense construction,and medical fields,the working conditions of robots have become more and more complex.As a medium for the interaction between robots and the environment,researchers have paid attention to manipulators.The earliest multi-finger manipulators are usually full-drive hands.Each joint of this manipulator is equipped with a driver,which is characterized by precise control of the movement of each finger joint.However,this kind of manipulator does not have self-adaptability and requires a complex control system.To solve this problem,the underactuated hand has become a new design scheme of the robot hand.By adding a spring or a coupling mechanism,the control system of the manipulator is simplified,and the manufacturing cost and difficulty are reduced.However,the emergence of the underactuated hand solves the problems of poor adaptability and complex control of the full-actuated hand,while also reducing its accuracy and dexterity,making it unable to accurately grasp small objects and cannot It is good to envelop irregular objects with complex shapes.Based on the above reasons,this article aims to improve the adaptability and accuracy of the underactuated hand,and designs and analyzes the underactuated hand based on the metamorphic principle.The main content of this thesis includes underactuated hand structure design,structural working process analysis,proposal of joint kinematics modeling method,underactuated finger kinematics modeling,statics modeling,dynamics modeling,virtual prototype establishment,Dynamic simulation analysis,prototype production and experimental analysis.The specific work content is as follows:(1)The structure design of the underactuated hand is completed by using the topology diagram and the adjacency matrix,and the configuration transformation analysis and working process analysis are carried out on it.First,establish the topology map and adjacency matrix of the underactuated finger according to the metamorphic principle,thereby obtaining the corresponding configuration of each configuration of the underactuated finger,and complete the structural design of the underactuated finger;then according to the operating requirements of the underactuated hand,its transmission system Carry out design and analysis,and finally get the structure of the underactuated hand and build its three-dimensional model.In addition,the configuration transformation analysis of the underactuated finger is carried out,and the working process of a single underactuated finger and the whole underactuated hand are analyzed and described in detail.(2)A kinematics joint modeling method based on the D-H parameter method and the closed vector equation is proposed,and the kinematics model of the underactuated finger is established using this method,and its statics model is established.By analyzing the structural characteristics of the underactuated finger,it is equivalent to the combination of a multi-degreeof-freedom 3R open chain mechanism and a single degree of freedom closed chain mechanism.The DH parameter method is used to establish the kinematics model and inverse kinematics model of the 3R mechanism.The vector equation obtains the kinematics model of the singledegree-of-freedom closed-chain mechanism,and finally combines the kinematics relationship between the parts of the underactuated finger to obtain the kinematics model of the underactuated finger.In addition,in order to obtain the contact force between the underactuated finger and the target object,a static model of the underactuated finger is established using the principle of virtual power.(3)According to the movement characteristics of underactuated fingers in different configurations,the dynamic model is established based on the Lagrange equation.Based on the kinematic analysis of the underactuated fingers,the dynamic models of the underactuated fingers in different configurations are established.Through the generalized coordinate representation of the kinematic parameters of the underactuated fingers,the partial velocity,Similar velocity and the equivalent moment of inertia in each configuration of the underactuated finger,the power and potential energy of the underactuated finger in different configurations are calculated,and finally the Lagrange equation is substituted into the dynamic model of the underactuated finger.(4)Establish a virtual prototype of the underactuated hand and perform simulation analysis on its working process.In addition,make an experimental prototype of the underactuated hand,conduct performance tests and carry out grasping experiments.A virtual prototype of the underactuated hand is established in ADAMS,and the process of the underactuated hand grabbing spheres and irregular objects is simulated,and various parameters in the working process are obtained.Using 3D printing technology to complete the production and assembly of the various parts of the underactuated hand,and conduct the overall performance test of the underactuated fingers and the underactuated hand.After that,a grasping experiment of the underactuated hand was carried out,and it was verified by grasping different target objects.It has good adaptability and accuracy,which proves the feasibility of the designed structure.