Redundant mechanical arm real-time look-ahead trajectory planning method based on NURBS curve interpolation algorithm

Abstract

The invention discloses a redundant mechanical arm real-time look-ahead trajectory planning method based on an NURBS curve interpolation algorithm, and relates to the field of redundant mechanical arm application. According to the method, a tail end planning interpolation speed is obtained by giving a tail end target path point of the mechanical arm, constructing an NURBS parameter curve as a tail end expected path and adopting an acceleration and deceleration control algorithm, mechanical arm tail end path errors caused by interpolation are considered in a Cartesian space, the interpolation speed is limited according to bow height errors, a look-ahead algorithm is introduced, and the end planning interpolation speed is obtained. The interpolation speed is scaled by considering the joint speed and acceleration constraint of the mechanical arm, meanwhile, prediction of a deceleration point is achieved, NURBS curve interpolation is achieved through a pre-estimation correction method to obtain a tail end expected track, joint variables are solved through inverse kinematics, and joint limiting is achieved through redundancy characteristics and a gradient projection method. Real-time trajectory planning meeting the kinematics constraint condition of the mechanical arm is achieved, and the tail end trajectory tracking precision is guaranteed on the premise that the physical limit of the mechanical arm is not exceeded.

Description

technical field [0001] The invention relates to the technical field of application of redundant manipulators, in particular to a real-time forward trajectory planning method for redundant manipulators based on NURBS curve interpolation algorithm. Background technique [0002] In the working space of the end effector of the manipulator, a series of discrete target path points are known, and industrial robots mostly use linear and circular interpolation methods for path fitting. However, for complex paths, a large number of straight line segments and arc segments are required, the calculation process is complicated and the path smoothness is difficult to guarantee. [0003] Because the spline curve has the characteristics of good continuity and uniform curvature change, it is suitable for fitting the free configuration curve. Therefore, some people have used the spline curve to plan the trajectory of the manipulator. However, the existing trajectory planning method of the man...

AI Technical Summary

Problems solved by technology

However, the existing trajectory planning method for manipulators implemented by spline curves has the following technical problems: the robot control system is highly constrained, the joints have boundary positions, and the joint speed and acceleration are limited by the driver

Since the joint space is not linearly related to the workspace of the end effector, if the trajectory planning is only performed on the end of the manipulator in the workspace, the joint variables may be saturated during execution, causing the end effector of the manipulator to deviate from the desired trajectory. A large tracking error may occur, which may even cause the robot arm to collide with other objects in the workspace, and eventually stop urgently

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