Research On The Motion Characteristics And Control Strategy Of SCARA Manipulator

In recent years, thanks to the development of related technologies and the promotion from relevant national policies, manipulators have been used in increasing amounts in the automation solutions of industrial production. Aiming at achieving automation of electronic component plug-in, this paper designs a new SCARA manipulator and conduct related research and analysis on it, using existing technologies both at home and abroad.First, according to the actual requirements of assembly of electronic components, this paper determines the design parameters index of the manipulator and lays the basis for the structural design. By comparing the advantages and disadvantages of the performance of related devices, taking the actual situation of manipulator design into consideration, the paper selects AC servo motor and harmonic gear to apply to the joint structure of the manipulator. With the help of an aided design software named ‘Solidworks’, the detailed design and assembly of the various parts are completed.Secondly, this paper uses D-H method to establish the coordinate system model of the manipulator and determine the model parameters according to the size of the designed mechanism. On the basis of representation and transformation theory of links in the coordinate system, the author tries to carry out forward kinematics analysis and obtain the forward kinematics equations of the manipulator. By solving the equations of forward kinematics solution results reversely with algebraic method, the corresponding expressions of the joint variables are achieved. Simulations in MATLAB and ADAMS jointly verify the reasonableness of the method and accuracy of the results in kinematic analysis.Next, this paper analyzes the equilibrium of the force on connecting rods under static conditions to acquire the solving equations of static forces inside the manipulator, and solve the problems under the simulated forces. Do derivations of the expression movement characteristic in the movement such as the speed of the connecting rods and accelerated speed. Respectively calculate the inertial forces and moment forces in the course of the body movement via Newton-Euler equations, and build the corresponding equations to conduct kinetic analysis under the new equilibrium conditions. Similarly, do the simulation verification by MATLAB and ADAMS.Then, this paper does research on trajectory tracking control strategy suitable for the first two joints of the manipulator designed, based on the Sliding Mode Control theory. This paper designs the control laws based on the equivalent control forms, and determine reasonable sliding surface parameters by comparing the error curves under different conditions of sliding parameters. Simulate the strategy based on the equivalent control forms under reasonable parameter settings. Taking the exponential reaching law as an object, the author studies the application of control law on the control strategy, and the influence that the parameters have on the system quality via comparing simulation results under different conditions parameters. Formulate new reaching law and design appropriate control law, on the basis of combining exponential reaching forms with the double exponential reaching method. Verify the improvement of the new reaching law by simulating the control effects the single exponential and new reaching law.Finally, based on the analysis and simulation, the SCARA manipulator and the additional control units are developed, jointly with Dongguan Research Institute of UESTC. This paper made a brief introduction to the physical structure and the control units of the SCARA manipulator prototype.