Point-to-Point Control Command for Suppressing Residual Vibration

In large areas of laser drilling, the residual vibration occurs when the sample stage moves in PTP (Point to Point) movement. It affects the surface quality and processing efficiency of the holes. The common solution for this problem is to set the laser irradiation delay time by the controller to wait for the residual vibration attenuation, but the whole drilling circle will increase. In this paper, a new method is introduced to reduce the laser drilling circle. By setting the allowable threshold of the residual vibration for the subsequent process, the sum of the time in deceleration segment of the trapezoidal moving profile, and the time when the residual vibration attenuates below the amplitude threshold (ST) can be minimized as the optimization goal. The results show that for a given operating speed, there is always an optimum acceleration value for the deceleration segment of the trapezoidal moving profile, which minimizes the ST value. Further, the delay time for laser irradiation can also be estimated according to the optimal acceleration during laser drilling.

Download Full-text

Friction-Compensating Command Shaping for Vibration Reduction

Journal of Vibration and Acoustics ◽

10.1115/1.1924637 ◽

2004 ◽

Vol 127 (4) ◽

pp. 307-314 ◽

Cited By ~ 24

Author(s):

Jason Lawrence ◽

William Singhose ◽

Keith Hekman

Keyword(s):

Steady State ◽

Coulomb Friction ◽

Vibration Reduction ◽

Input Shaping ◽

Residual Vibration ◽

Command Shaping ◽

Point Motion ◽

Common Operation ◽

Point To Point ◽

Theoretical Developments

Fast and accurate point-to-point motion is a common operation for industrial machines, but vibration will frequently corrupt such motion. This paper develops commands that can move machines without vibration, even in the presence of Coulomb friction. Previous studies have shown that input shaping can be used on linear systems to produce point-to-point motion with no residual vibration. This paper extends command-shaping theory to nonlinear systems, specifically systems with Coulomb friction. This idea is applied to a PD-controlled mass with Coulomb friction to ground. The theoretical developments are experimentally verified on a solder cell machine. The results show that the new commands allow the proportional gain to be increased, resulting in reduced rise time, settling time, and steady-state error.

Download Full-text

Rest-to-Rest Motion of an Experimental Flexible Structure Subject to Friction: Linear Programming Approach

Journal of Vibration and Acoustics ◽

10.1115/1.4000460 ◽

2010 ◽

Vol 132 (1) ◽

Cited By ~ 3

Author(s):

Rajaey Kased ◽

Tarunraj Singh

Keyword(s):

Linear Programming ◽

Controller Design ◽

Open Loop ◽

Programming Approach ◽

Pulse Control ◽

Test Bed ◽

Residual Vibration ◽

Linear Programming Approach ◽

Point To Point ◽

Harmonic System

A linear programming approach designed to eliminate the residual vibration of the two-mass harmonic system subject to friction and undergoing a point-to-point maneuver is proposed and implemented on an experimental test bed. Techniques for design of positive pulse control profiles for nonrobust and robust open loop controller design are explored, where the positive pulses initiate motion and the friction force brings the system to rest. It is shown that consistent results can be obtained from experiments and the robustness against frequency uncertainty results in the reduction in residual vibration as well as steady-state error.

Download Full-text