Research On S-shaped Continuous Trajectory Planning

In the industry field, CNC machine tools become more and more important. Companying with the complexity of objects, the more accuracy is needed for CNC machine tools. In order to ensure the processing precision, the stationary of operation is also very important for the CNC machine tools.By analyzing the speed curve, there are some points with the same trends in the speed profile. The velocity fluctuations of these points cause unwanted vibrations of CNC machine tools. To eliminate these vibrations, the thesis proposes a search algorithm based on the curve fitting which looks for the same trend points. This algorithm utilizes the common characteristics of speed points, and selects the processing section. Followed by a large trapezoid curve approximation method, this trend is a large section of order trapezoidal velocity curve, while the original location information is mapped to a large trapezoidal speed curve. To further smooth speed curve, the ascending and descending segment of the S-velocity curve and sinusoidal speed curve are used instead of the large trapezoidal speed curve that eliminates the velocity fluctuations of convergence of velocity and smoothes the machine speed.Applying this algorithm to some simulation experiments of actual processing path, the velocity fluctuations in the same trend have been obviously weakened. The corresponding acceleration fluctuations also have been moderated. The smooth transition effect at the connection points eliminates the machine vibration of increasing acceleration.