Speed planning method during NURBS curve interpolation of industrial robot

Abstract

The invention relates to a speed planning method during NURBS curve interpolation of an industrial robot. The method comprises that (1) a characteristic equation, based on a parameter u and a feed velocity v, of an NURBS curve is established; (2) a velocity constraint relation, based on the geometrical constraints as centripetal acceleration and chord-height error, of the NURBS curve is established; and (3) according to the fact that the feed speed in the robot end changes monotonously, predictive speed segmentation is carried out on the NURBS curve to obtain a segment point interpolation parameter set, and a speed planning process is completed. The speed planning method is especially suitable for the NURBS curve in which multiple teaching points are known, a movement track of the robot end needs to be smooth, and the movement speed and acceleration of the robot end cannot change abruptly; the geometric characteristics of the NURBS curve are taken into consideration when speed limitation is established; the curve is segmented predictively according to the monotonicity of speed change; and impact on the robot during NURBS curve interpolation is greatly reduced.

Description

technical field [0001] The invention relates to the application field of six-axis industrial robots, in particular to a speed planning method for industrial robots during NURBS curve interpolation. Background technique [0002] NURBS is a widely used spline curve. It can not only be used to describe free curves and surfaces, but also provide a unified expression for various geometries including conic curves and surfaces. The traditional application of NURBS in the path interpolation of industrial robots mainly adopts the method of approximating the curve with a small straight line. This method has the disadvantages of low trajectory accuracy, large amount of calculation, slow interpolation speed, and uneven trajectory. [0003] The NURBS curve path interpolation process of a six-axis industrial robot needs to meet the following two requirements: the curve trajectory generated according to the teaching points is smooth and has no sudden changes, and the number of teaching poi...

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Problems solved by technology

[0004] In recent years, an interpolation method based on the curve parameter equation of the parameter u has appeared in China. However, in terms of speed planning methods, uniform or trapezoidal acceleration and deceleration speed planning is mainly used. This method can obtain smooth and no sudden change trajectory, but The feed speed at the end of the robot cannot be adaptively changed according to the geometry of the curve, which may easily cause the robot to be subject to large shocks and vibrations during the interpolation process

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