Feedrate interpolation with axis jerk constraints on 5-axis NURBS and G1 tool path

摘要

A key role of the CNC is to perform the feedrate interpolation which consists in generating the setpoints sent to each axis of a machine tool based on a NC program. In high speed machining, the feedrate is limited by the velocity, acceleration and jerk of each axis of the machine tool. The algorithm presented in this paper aims to obtain an optimized feedrate profile which makes best use of the kinematical characteristics of the machine. This minimum time feedrate profile is computed by intersecting all the constraints due to the drives in an iterative algorithm. It is worth noting that both tangential jerk and axis jerk are taken into consideration. The proposed VPOp (Velocity Profile Optimization) method is universal and can be applied to any articulated mechanical structure as it is demonstrated in the examples. Moreover the algorithm has been implemented for various formats: linear interpolation (G1) and NURBS interpolation in 3- and 5-axes. The effectiveness of the algorithm is demonstrated thanks to a comparison with an industrial CNC and can be freely tested using the VPOp software which is available on the Internet http://webserv.lurpa.ens-cachan.fr/geo3d/premium/vpop.