Trajectory Planning For High Speed And High Precision CNC System

In recent years,CNC technology has become the core and foundation of the manufacturing industry with its excellent productivity and wide range of application.Among the key technologies in the field of numerical control,the performance of trajectory planning is the fundamental reason that determines the processing efficiency and accuracy.In order to meet the requirements of high-speed and high-precision for CNC system,the trajectory planning of the curve has become a research hotspot in the field of numerical control.However,it still can't be able to go to the industrial application site.In this paper,a complete set of high-speed and high-precision solutions are proposed for the trajectory planning.In the trajectory planning,whether the uniaxial performance of the machine tool can meet the requirements is the key to achieve high-speed and high-precision for CNC machining.Based on the theory of particle kinematics,this paper presents a performance limit algorithm for uniaxial velocity,uniaxial acceleration and uniaxial jerk.In this paper,a complete flow chart of real-time trapezoidal trajectory planning for NURBS curves is designed.The single-axis performance limit algorithm is combined with the improved trapezoidal speed programming mode.And an adaptive cumulative error compensation algorithm is designed during curve interpolation.The real-time trapezoidal trajectory planning of NURBS curve satisfying the single-axis speed and single-axis acceleration of the machine tool is realized.Based on this,the paper improves the trapezoidal trajectory planning process,and designs the S-type look-ahead algorithm and speed planning algorithm of NURBS curve,and combines the uniaxial performance limit algorithm and S-type speed planning mode,which greatly simplifies both the S-type Judging from the seventeen specific speed planning modes and the finding of deceleration point,the S-type planning of NURBS curve that satisfies the uniaxial velocity,uniaxial acceleration and uniaxial acceleration is finally achieved.The simulation results show that the final federate and deceleration in each interpolation cycle of the trapezoidal trajectory planning satisfy the setting single-axis limit values,and the final federate,acceleration and jerk in each interpolation cycle of the S-type trajectory planning satisfy the setting Single-axis limit value.Both the trapezoidal trajectory planning and the S-type trajectory planning can meet the requirements of real-time machining.Butterfly trajectory is taken as an example to conduct the actual machining experiment.The experimental results show that the NURBS curve trapezoidal trajectory planning has smaller tracking error and vibration peak amplitude than the solid state high-tech look-ahead algorithm.Compared with the NURBS curve trapezoidal trajectory planning,the advantages of S-type trajectory planning for tracking error are not obvious,but the vibration peaks in trapezoidal trajectory planning are basically eliminated.