Planning and implementation of motion trajectory based on C2 PH spline

Generally, poor machining performance may occur due to the abrupt change of acceleration at the portion of a curve with large curvature. In order to deal with this problem, this paper presents a modified trajectory planning scheme based on PH (Pythagorean Hodograph) curves for sharp corner angle contouring tasks. The main idea of the proposed method is to force the actual toolpath trajectory closer to the original command path by exploiting a modified command trajectory (a C² PH spline curve) at the sharp corner in advance, so that the corner contouring accuracy can be further improved. Finally, several different sharp corner contour-following experiments were conducted on dual servo motors to evaluate the effectiveness of the proposed approach. Experimental results indicate that the proposed approach can indeed reduce contour error in sharp corner-angle contour-following applications.