Command shaping control for micro-milling operations

Abstract

Micro milling requires both high speed and high accuracy in order to economically produce parts with features on the scale of 1 µm. Micro mills are smaller and more flexible than traditional large-scale machines. Therefore, vibration of the machine structure is a significant problem. Given that micro milling requires high positioning precision, even small vibrations in the controller dynamics are problematic. The small-scale operation has considerably lower tool/workpiece interaction forces than traditional-scale milling. These low cutting forces have minimal effect on the machine structural response. Therefore, the dominant dynamic factor in exciting vibration can be the machine tool motion, rather than the workpiece/tool interaction. Given this realization, properly shaping the motions of the micro mill is a promising approach to reduce vibration. This paper presents a nonlinear commandshaping technique to reduce the vibrations of a micro mill that can be implemented with a standard CNC controller. The robustness of this technique to modeling errors and disturbances is investigated. Theoretical proofs and experimental demonstrations of the command-shaping technique are presented. The improved performance from the command shaping enables higher throughput and improved accuracy of the micro mill.

Quantitative Feedback Input Shaping for Flexible-Joint Robot Manipulator

“…18 (bottom)) for all the 27 plant cases. Their magnitudes are well within the specifications (11) and (12) as was designed for. Note that the limits À10 dB ¼ 0:316 are still conservative because only around 70% of the disturbance was aimed to be rejected.…”

“…Since then, the input shaping technique has been applied to various flexible systems. Recent applications include vibration suppression in marine crane [4], liquid sloshing [5], flexible spacecraft [6], cam follower [7], hard disk drive [8], cherry picker [9], atomic force microscope [10], micromilling machine [11], quadrotor [12], fuel transport system of nuclear power plant [13], and automotive wiper [14].…”

Motion control of a two-axis linear motor-driven stage in the micro-milling process

“…28 Few researchers have reported exprimental works on machine tools closer to industrial conditions. 7,19,29,32,33 Cross-coupling control has been employed in a miniaturized NC micro milling machine tool. 34 A nonlinear command shaping technique was proposed to reduce the vibrations in the micro-milling process.…”

“…34 A nonlinear command shaping technique was proposed to reduce the vibrations in the micro-milling process. 35 Dynamic dislocation compensation in micro milling machine tools has also been extensively studied. 36 The main contribution of this paper is to propose a suitable controller for a two-axis stage driven by linear motors capable of achieving the requirements of micro milling.…”

“…28 Few researchers have reported exprimental works on machine tools closer to industrial conditions. 7,19,29,32,33…”