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Feedrate scheduling with kinematic constraints is a challenging problem for five-axis machining. Linear and rotary drives of five-axis machine tools have different capabilities and limits. The main issue is that the feedrate profile generated by the existing five-axis feedrate scheduling method might violate kinematic constraints since the tangential and axial jerk could not be directly correlated due to nonlinear kinematics transformation. In this paper, a novel master-based feedrate scheduling (MBFS) approach with real-time and drive constraints is developed to generate smooth trajectories along five-axis linear toolpaths. Based on inverse kinematic equations, tooltip feed parameters are evaluated by a five-axis feed regulation formula (FFRF) such that axial velocities, accelerations, and jerks could be constrained within given limits simultaneously. The tooltip or rotary axis having the largest motion duration is selected to be the master, and the others are regarded as the slaves which move with the master synchronously. Rather than planning the feedrate profile using the curve parameter algorithm, linear and angular trajectories are planned by matching the same motion duration to realize time synchronization of five-axis motion. The local corner smoothing method is adopted to blend the velocities of the motion axes and generate cornering trajectories while satisfying corner position tolerance and drive constraints. Finally, experiments are conducted on a five-axis engraving machine to verify that the proposed method can satisfy the kinematic constraints, and improve tracking and contour accuracy. [ABSTRACT FROM AUTHOR]

This paper presents an integrated servo-feed-drive model including the cutting force and structural effect to predict tracking errors in an end-milling process. Most conventional approaches consider the cutting force to be an equivalent torque to servo feed drive. However, in addition to acting as the equivalent torque to the servo feed drive, cutting forces also cause the machine table to vibrate. This paper considers the aforementioned cutting-force effects to predict tracking errors and then verifies the tracking errors using experimental results. Experiments are conducted on a 3-axis computer numerical control (CNC) machining center to validate the tracking errors predicted by the proposed servo-feed-drive model. For one case study, the peak-to-peak tracking errors from the experimental, proposed, and traditional models are 3 μm, 2.8 μm, and 0.5 μm, respectively, for the x-axis, and 2.1 μm, 1.7 μm, and 0.4 μm, respectively, for the y-axis. The experimental results illustrate that the tracking errors predicted using the proposed model are more accurate than those predicted using the traditional model without consideration of the transmission path. Therefore, it can be concluded that the proposed integrated model provides much accurate tracking-error prediction, and thus, the ball-screw and machine-table flexibilities should be considered. [ABSTRACT FROM AUTHOR]

In this paper, an integrated dynamic acceleration/deceleration (IDAD) interpolation algorithm which combines the acceleration/deceleration before interpolation (ADBI) and acceleration/deceleration after interpolation (ADAI) is proposed. The IDAD scheme could confine the maximum contour error at the junction of a linear line (G01) block under consideration of the command and servo dynamic errors. The contour error formulation for the IDAD is derived analytically and then utilized for interpolation design. Because the error formulation could predict the command and dynamic errors analytically, the IDAD could adjust the connecting velocity of two blocks such that the overall contour errors are bounded within the given tolerance. The simulation results validate the proposed algorithm that can reduce the contour errors by 50 % but only an increase of 10 % machining time as compared to the integrated acceleration/deceleration (IAD) interpolation technique. [ABSTRACT FROM AUTHOR]

Modern motion control adopts acceleration/deceleration before interpolation (ADBI) motion planning to eliminate path command errors. However, the individual velocity profiles might not be continuous at the junction of the blocks. Acceleration/deceleration after interpolation (ADAI) method may provide an alternative for solving the discontinuous problems, but it causes path command errors. In this paper, an integrated acceleration/deceleration interpolation (IAD) scheme which integrates the ADBI and ADAI modules is proposed. The ADBI provides a look-ahead function which plans the feedrate profiles based on chord errors, command errors, curvatures, and acceleration limits. Within the look-ahead function, the command error equation is utilized to determine the feedrate at the junction of adjacent blocks. Then the ADBI performs non-uniform rational B-spline (NURBS) interpolation using the planned feedrate profile and outputs the position points to the ADAI module. The ADAI module processes the points by a digital convolution technique such that the continuity of the block junction velocity is ensured. Finally, the IAD is applied to the multi-block NURBS interpolation to validate its effectiveness. Simulations and experiments are conducted to demonstrate the IAD scheme. It is shown that the IAD scheme can reduce the acceleration significantly at the junctions of the blocks under the given tolerance of the command error. Furthermore, the proposed algorithm can improve tracking and contour accuracies as compared to the hybrid multi-blocks look-ahead approach. [ABSTRACT FROM AUTHOR]

In the accepted paper, the authors' affiliation has been wrongly typeset as People's Republic of China, but this should read Taiwan. The correct affiliations are shown below. [ABSTRACT FROM AUTHOR]