The Study Of Kinematics And Dynamics On Several Hybrid/Parallel Arm-hand Mechanism

The traditional manipulator is generally composed of a robot arm and an end effector.Most of the robot arms are in series configuration and are used to achieve a wide range of movement and location.The end effector is used to perform a precise location and interacts with the outside objects to complete the required operations and tasks.In this thesis,the hybrid arm-hand and parallel arm-hand composed of hybrid mechanical arms,parallel mechanical arms as well as fingers are studied to design a variety of hybrid and parallel arm-hand mechanisms.It is expected to apply it to production assembly,product sorting,pipeline maintenance,disaster relief and other areas facing the unstructured environment and tasks.Compared with the traditional serial mechanical arm + gripper manipulator,it has some advantages in terms of stiffness,precision,versatility and flexibility.Besides,it also has the advantage of manufacturing cost,stiffness,accuracy,and dynamic response performance compared with the humanoid multi-fingered hands.The main contents of this thesis are as follows:The basic theory and general model for the hybrid arm-hand mechanism are established.Firstly,the special variables are defined to describe the connection between fingers and moving platform and the distribution of fingers,and the solution formulas of these variables are established;and then fingers and parallel mechanisms are separated and analyzed separately in the respective coordinate systems to establish their own kinematics models;next,these separate models are combined together to derive the general model of forward kinematics solution of the points on fingers;finally,based on the principle of virtual work,a general model of statics and dynamics of the hybrid arm-hand mechanism is established.Three kinds of hybrid arm-hand mechanism are analyzed.Firstly,there is a design about two kinds of hybrid arm-hand mechanism with RRPS compound-driven branch and one with 3-SPR mechanism as the main body;next,these mechanism are used to establish the model of position inverse solution aiming at the grabbing of cylinders;and then by using the stepwise densification of the sampling method and dichotomy to iteratively search for the fixed orientation-workspace of 3-RRPS and 2-RRPS + SPR parallel mechanism and the fingertip workspace of the 3-RRPS 3-finger parallel mechanism is drawn on the basis of the positive solution of the position;next,the fingers and parallel mechanisms are analyzed separately.The solution of speed,acceleration,statics and dynamics of the three kinds of hybrid arm-hand mechanisms are carried out by using the general model established in this thesis.Finally,their simulation models are constructed,and the theoretical models are verified by numerical examples.The experimental study on 3-SPR hybrid arm mechanism is carried out.Firstly,the experimental platform of 3-SPR hybrid arm is set up and the control system is built by using the structure of PC+motion-control card;next,a new method of virtual teaching on CAD variable geometry is proposed;and then the secondary development of a CAD software is done by using C# language and the software of robot virtual teaching is written;finally,there is an experimental study on motion planning,teaching and motion control of 3-SPR hybrid arm mechanism by using the software,and an error analysis and theoretical verification.A kind of finger-leg compound parallel mechanism is analyzed.First of all,based on the 3-UPUR + SP parallel mechanism,a new finger-leg compound parallel mechanism is proposed;after that,considering the characteristics of the mechanism,a position inversion model is established for four kinds of situations that may be encountered during the progress of motion and grabbing;next,the constraint equations of the mechanism are established and solved by the numerical method and the direct kinematics of the parallel mechanism are obtained;besides,by establishing an equivalent virtual straight branch for the surrounding three branches,the Jacobian matrix and the Hessian matrix of the mechanism are solved and then there is a realization of the solutions to the positive solution formula of acceleration and speed about the moving platform,grabbed objects,fingers,fingertips and the simplified formula of fingertip speed as well as the simplified formula of fingertip speed of grabbing objects;furthermore,the models of statics and dynamics are established by using the principle of virtual work;finally,the simulation model is established and the correctness of the theoretical model is verified by numerical examples.