Research On ACC/DEC Control And Contour Error Of CNC System

Based on CNC system motion control,a significative research was made on motion smooth processing and contour error of CNC system, mainly involving:Motion smooth processing of CNC system and control methods of flexible ACC/DEC, as well as analysis of multi-axis motion contour error model and its contour error compensation methods. The validity and practicability of the methods mentioned above are checked by experiments. Control methods of the Trigonometric Function Squared Sine Shape Curve (TFSSSC) are introduced. ACC/DEC related functions of Trigonometric Function Squared Sine Shape Curve are constructed, ACC/DEC mathematical model of sine function square curve is established, and ACC/DEC algorithm’s motion smoothness of sine function square curve is analyzed. The motion smoothness of Trigonometric Function Squared Sine Shape Curve is analyzed. The algorithm’s smooth continuity of speed, acceleration and jerk is validated combined with motion smoothness experiment.(1) Motion smooth processing of CNC system was studied in the following processing. Firstly, analyses are made for common ACC/DEC control method. Then, ACC/DEC control method of quartic curve and algorithm theory and implementation of trigonometric function cosine acceleration and deceleration are discussed in detail. Finally, the mentioned ACC/DEC curves are compared. Their advantages and disadvantages and existing problems are pointed out. Based on sine function’s infinite continuous differentiability and construction principle of flexible ACC/DEC algorithm, the square curve ACC/DEC method of sine function is put forward, ACC/DEC related functions of Trigonometric Function Squared Sine Shape Curve is constructed, ACC/DEC mathematical model of sine function square curve is established, ACC/DEC algorithm’s motion smoothness of sine function square curve is analyzed. The algorithm’s smooth continuity of speed, acceleration and jerk are validated combined with motion smoothness experiment. The smooth handling of high performance CNC system’s motion is realized,which solved the acceleration and jerk’s discntinuity problem of traditional ACC/DEC control.(2) A CNC system multi-axis motion contour error model was studied. On the basis of analyzing the generation of contour error of CNC multi-axis motion continuous track control, the method of improving the contouring accuracy and reducing the contour error is studied. Error models of beeline contour, arc contour of different radius of curvature and common contour of curve are established. The formation mechanism of CNC system contour error is analyzed. Based on tangent contour error coordinate theory, the estimation method of tangent contour error is raised, the model of free curve optimization contour error is created, the spatial contour error of multi-axis CNC is analyzed. These researches provided a theoretical basis for reducing contour error.(3) A contour error compensation method for CNC system multi-axis motion was studied. A compensation method is introduced by analyzing the dynamic characteristics of servo system’s effect on contour error. The method is implemented including two parts, which are the design and the integrating of multi-axis motion contour controller. The effectiveness of the method is verified combined with simulation experiments.