Trajectory Planning Of Vertical Multi Joint Robot

The development of science and technology has brought about the innovation of robot technology.From the original robot which can only execute the teaching and reproduction,to the robot with preliminary perceptual programming ability,and to the highly intelligent robot,the robot technology has experienced a rapid development of 60 years.Nowadays,robots play an important role in industrial production,and show a great prospect of development.Although the robot technology is progressing rapidly,the trajectory planning of six axis robot is always a difficult problem.When the end actuator is running in the space straight line,space arc and other tracks,there will still be problems such as too much calculation,too large impact of joint axis and long running time,which leads to the use of the robot in some occasions with high trajectory complexity is limited.Therefore,the research on robot operation trajectory is a key and difficult point in robotics.The research object of this paper is a vertical multi joint robot,which is suitable for industrial sorting occasions,and can complete the grasping and placement of working objects.This paper first analyzes the body mechanism of the robot,then selects the joint space trajectory algorithm and obtains the trajectory,and uses the multi-objective optimization algorithm to optimize the trajectory,finally completes the selection of control system components and the construction of the experimental platform,uses the experimental platform to verify the trajectory,and obtains the trajectory planning method of vertical multi joint robot.The main research contents are as follows:(1)Mechanism analysis of robot body.Inertia mechanics,workspace,maximum speed,torque and dynamics of the existing vertical multi joint robot are analyzed and calculated,and the conclusions are used to guide the trajectory planning in the following chapters.(2)Research on motion trajectory.By setting the conditions of trajectory motion and using Cartesian space trajectory planning,two groups of intermediate point pose matrices of space straight line trajectory planning and space arc trajectory planning are obtained.Then,for the joint axis,cubic polynomial,quintic polynomial and cubic spline interpolation trajectory planning algorithm are used to draw velocity time and acceleration time images.The optimal algorithm is selected according to the image,and the motion trajectory is obtained by interpolation,which is used for multi-objective optimization.(3)Multi objective trajectory optimization.Starting from the analysis of multi-objective optimization algorithm,two multi-objective algorithms NSGA-II and MOEA / D are selected to optimize the trajectory after planning.After comparing the two algorithms,it is concluded that the two algorithms have similar trajectory optimization results,and MOEA / D has faster convergence speed.By comparing the unoptimized cubic spline interpolation,we know that the joint impact is smaller after optimization.(4)Experimental verification.According to the experimental conditions for trajectory verification,the requirements of the control system are analyzed,and then the components of the control system are selected through the requirements analysis.Draw the control system circuit diagram,use the control system components to build the experimental platform,design the human-machine interface and write the control program.By running the optimized trajectory,the experiments of arc interpolation and linear interpolation are carried out respectively.The results show that the joint axis of the robot runs smoothly without obvious shaking,which indicates that the optimized cubic spline interpolation trajectory is suitable for vertical multi joint robot.