| In recent years,with the reduction of demographic dividend and the increase of labor costs,as well as economic globalization and technological innovation,many countries have focused on the transformation and upgrading of manufacturing industry.Especially under the influence of Germany's "industrial 4","intelligent manufacturing" and "made in China 2025",many enterprises of most countries are undergoing transformation and upgrading.One of the most significant features is that industrial robots appear on the production lines of various industries.As a special member of industrial robot,parallel robot is widely used in food,light industry,medicine and electronic products because of its high response,high precision and high stiffness.It has completed the repetitive task of sorting,catching and packing.In this paper,the linear driving parallel robot is developed by changing the driving mode from rotary to linear driving based on the traditional Delta parallel robot.Compared with the traditional Delta parallel robot,it has the advantages of strong load capacity and large stiffness.But this kind of parallel robot still has less research in some respects,such as kinematics,dynamics model,workspace,size optimization,path optimization,control strategy and control system,etc.This paper takes the trajectory planning and control system as the main line,and studies the linear driven parallel robot from several aspects,such as kinematics,workspace,trajectory planning and control system.The main research contents of this paper include:(1)The establishment of the kinematic model and the solution of the workspace.On the basis of analyzing the mechanical structure of the linear driving parallel robot,the degree of freedom is solved.Based on its structural characteristics,the geometric model is established.The inverse kinematics and the forward kinematics of the linear driven parallel robot are obtained by using the vector method on the basis of the geometric constraint of the rod length.The velocity model and the acceleration model are obtained for its derivation.On the basis of inverse kinematics and Hooke hinge constraint,a polar variable step iterative search method is proposed to solve its workspace.(2)Analysis and optimization of trajectory planning.There exist some problems such as uneven motion,shock and jitter in the pick and place operation process of the linear driving parallel robot.This paper improves the design of the existing gate shape path by using the continuous curve of curvature.In order to simplify the complexity of derivation,the function expression is derived in the XOZ plane.Then,based on the modified trapezium acceleration law,with the optimal operation time as the goal,the optimization path parameters of the improved gate shape path are solved by using the improved ant colony algorithm.And trajectory planning in robot Cartesian space is carried out under the improved gate shaped trajectory and modified trapezoidal acceleration.(3)Design of the linear driven parallel robot's control system.Analyzing the advantages and disadvantages of the existing robot's control system,selecting the control system suitable for the parallel robot according to the characteristics of the parallel robot.A control scheme for parallel operation of multi processors is proposed according to STM32 MCU technology in the hardware design,and the design of each module in the hardware system is realized.For the software design,the program is designed for the functional modules of the parallel robot based on the LabVIEW development platform.(4)Virtual prototype simulation and test verification.On the basis of establishing the virtual prototype model of the linear driven parallel robot,the forward and inverse kinematics model is verified through the kinematics simulation of Adams.Analyzing the influence of the optimized door shape path on the robot's motion performance through the joint simulation of ADAMS and MATLAB.Using the laser tracker to test and verified the workspace of the robot,contrast with the workspace solved by the polar variable step iterative search method.Verified the feasibility of the designed control system based on the prototype test of the self-developed control system. |
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