Research On High-order Differentiable Algorithm Of Nc Instruction Interpretation And Experiments

CNC equipment is a typical electromechanical system, which is the basis of the equipment manufacturing industry. However, the components of CNC equipment, including NC system, servo system and mechanism, currently, are still in the stage of the independent research and development, ignoring the internal relationships among them, so it is not conductive for the performance of CNC system to be further improved. From the perspective of the internal relationships among them, the output information of NC instruction interpretation for time domain with high-order differentiability and multi-axis control system with the same cycle for trajectory control are studied. (To facilitate the presentation, the output information of NC instruction interpretation for time domain with high-order differentiability is abbreviated to NC instruction interpretation with high-order differentiability in this paper.)From the perspective of the performance optimization of the overall CNC equipment, the dynamic model of the controlled mechanism is built, and then which is used to research on the error-free trajectory tracking for the controlled mechanism. Based on the model of the error-free trajectory tracking, NC instruction interpretation with high-order differentiability is proposed, and then relevant in-depth research is performed. The timing characteristics of servo system is taken into account for the analysis of the process of the curve interpolation, and the interpolation method of the circular approach to the trajectory curve based on the control message of the acceleration is presented. (The realization of the above studies is based on the premise of the same cycle control.) An effective way to realize NC instruction interpretation with high-order differentiability and the same cycle control is pointed out.During trajectory planning, position, velocity and acceleration should satisfy the boundary condition simultaneously, if the interpolation cycle was directly used to discrete velocity, precision loss will occur. In order to solve these problems, a novel double acceleration control algorithm in the deceleration phase is presented and used to deal with linear acc/dec control, based on which a moving-average acc/dec control algorithm is studied, this algorithm can not only meet requirement for velocity and acceleration smooth control, but also realize NC instruction interpretation with high-order differentiability. The deduction of the invariance position is proposed, and the theory and deduction of the invariance position and high-order differentiability are proved. In addition, in order to solve the accuracy loss during the algorithm data processing in MCU for achieving the predominant ability, a float-int (F-I) data processing is researched. The simulation results demonstrate that the proposed algorithm and data processing are reasonable.For generating the high-order differentiable instruction of NURBS curve, NURBS curve interpolation is used by the proposed acc/dec control algorithm. Aiming at realizing NURBS curve interpolation of NC instruction interpretation high-order differentiable acce/dec control algorithm, after the process of linear acc/dec, velocity and position in the vicinity of the interpolation points of the junction point and extreme point, respectively, should be adjusted to avoid affecting the system interpolation performance when the velocity and position are dealed with the method of moving-average by use of the proposed deduction of the invariance position. The interval of the being fabricating curve is divided by the adjusted message, and then the distribution of the velocity of the algorithm in every interval is researched to accomplish the generation of the pre-interpolation information. In the real-time processing stage, based on these informations, the moving-average processing is used to generate control instruction of NURBS curve, and the algorithm flow is analyzed. Finally, some living examples are simulated, and the results show that the proposed instruction interpretation of NURBS curve has the characteristic of high-order differentiability, and the proposed algorithm is validity.The software architecture is designed. A multi-axis experiment system with the same cycle control based on NC instruction interpretation is built. Based on the AC permanent synchronous servo driver which has been successfully developed in our laboratory, the work principle of the master control card, slave control card, integrated power supply card, parallel communication interface card, etc, are analyzed in detail. These studies are useful of the realization of the same cycle control. Double port RAM is adopted to realize communication between the servo control driver and CNC system, so the data transmission efficiency, real-time and reliability have a great improvement. Finally, the instruction transfer protocol also is researched, and the reliability of the data transmission is verified.Based on the above results, the real-time of the multi-axis system with the same cycle control, NC instruction interpretation with high-order differentiability, and the comparison between the instruction interpretation and the data getting from the encoder are all tested. The experimental results show that this system can not only realize the instruction interpretation with high-order differentiability and the same cycle control, but also has a good trajectory tracking performance for instruction. Moreover, it also verified the feasibility of the theoretical analysis ahead of the algorithm design and the validity of the design of the acc/dec control algorithm, interpolation algorithm and control system. The work of this dissertation will provide theoretical foundation and practical experience for further research and design of CNC system.