| With the development of productivity and the increase of labor costs,simple and complicated labor is increasingly replaced by robots.As a link on the production line,robot has many advantages,such as high precision,high efficiency,low cost and so on,compared with manual labor.The country has also introduced the 2025 strategy,which will vigorously develop the robot industry as one of the nine strategies for the future national industrial development.The replacement of artificial labor by robots requires more output per unit time.From the technical level,the robot can produce more output per unit time through the time optimization of its running trajectory.Optimizing the running trajectory of robots can further tap the potential of robots,improve production efficiency and create more value for the society.In this paper,Stewart platform is taken as the research object,and its running trajectory is optimized in terms of time and smoothness for the application scenario of Stewart platform in parallel machine tool.Cubic spline interpolation was carried out for the trajectory points of the moving platform,and the displacement of each drive was solved by inverse kinematic solution.Since each drive arm moved in a relative straight line in space,the cubic polynomial was used for interpolation.The nonlinear optimization model is established,and the velocity and acceleration of the trajectory points of the driving arm are solved by genetic algorithm,so as to achieve the optimization goal of time-optimal trajectory smoothness.Main research contents of this paper:(1)the forward kinematics and reverse kinematics of Stewart are analyzed,and the kinematics model of Stewart platform is built by using the homogeneous transformation theory and spiral theory in space.The principle of singularity of Stewart platform is studied and the singularity configuration is analyzed.(2)inspired by the numerical method of combining numerical iteration with the forward kinematic solution to solve the workspace,the simulation software was used to iterate the motion of the driving arm,the simulation model output the spatial coordinates of the moving platform,and the workspace of the moving platform was solved after the simulation was completed.(3)the trajectory of Stewart's motion in the workspace is planned.The planned trajectory equation is discretized into the trajectory points,and cubic spline interpolation is used to interpolate and compact the trajectory points.The length of a set of driving arms corresponding to the trajectory points is obtained by inverse kinematic solution,and the trajectory of the driving arms is compressed by cubic spline interpolation.(4)to establish a working time shortest optimization objective function,at the same time,considering the speed,acceleration and acceleration of the robot and track running smooth as a condition of the end,through the genetic algorithm for discrete path,the velocity and acceleration of the band are,and the optimized operation time reduced from 3.186159 to 2.708309 s,optimization on run time by 14.9%,and the optimized acceleration curve is more smooth than before optimization.(5)The Stewart platform for dynamics analysis and builds dynamic model of the Stewart platform in ADAMS,and the driving arm establish displacement and velocity measurement,model of force and torque control strategy,the spline joint force optimized by the input data,will be driving arm of displacement measurement and to solve the data contrast,no significant difference between the two. |
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