scholarly journals Motion compensation for maritime cranes during time-varying operations at the pendulum’s natural frequency

2022 ◽  
Vol 168 ◽  
pp. 104573
Author(s):  
Ryan A. McKenzie ◽  
Rishad A. Irani
Keyword(s):  
Natural Frequency ◽  
Motion Compensation ◽  
Time Varying

Weld Pool Impedance Identification for Size Measurement and Control

1983 ◽  
Vol 105 (3) ◽  
pp. 179-184 ◽  
Author(s):  
M. Zacksenhouse ◽  
D. E. Hardt
Keyword(s):  
Control System ◽  
Natural Frequency ◽  
Time Varying ◽  
Arc Plasma ◽  
Size Parameter ◽  
Size Measurement ◽  
Full Penetration ◽  
Simulation Results ◽  
And Control ◽  
Measurement And Control

A primary indicator of weld quality is the size of the bead produced, and for full penetration welds this size parameter can be reduced to the width of the backbead. A method for determining this width in real-time is proposed that measures the natural frequency of pool motion when driven by a time varying arc plasma force. This method is developed analytically and verified experimentally for stationary weld pools. A control system based on this measurement scheme is also developed and simulation results are presented.

Parametric Vibration Responses of Electromechanical Integrated Toroidal Drive

2012 ◽  
Vol 271-272 ◽  
pp. 1383-1387
Author(s):  
Xiu Hong Hao ◽  
Xue Jun Zhu
Keyword(s):  
Natural Frequency ◽  
Parametric Vibration ◽  
Time Varying ◽  
Vibration System ◽  
Response Curves ◽  
Design And Optimization ◽  
Meshing Stiffness ◽  
Electromechanical Integrated ◽  
Vibration Responses ◽  
Time Domain Response

There are periodic changes of meshing teeth in electromechanical integrated toroidal drive, that lead to time-varying meshing stiffness. By converting time-varying stiffness into the form of Fourier series, dynamics model and the corresponding differential equation of parametric vibration system are established. Then approximate analytical solution of the system is obtained by multi-scale method, and time domain response curves of damping vibration system are given. The analysis results show that free vibration of the system not only include natural frequency, but also contains combination frequencies between natural frequency and meshing frequency. So there are multi-resonance frequency sections. Those will provide more theoretical supports for system dynamic design and optimization.

Application of a Fast Self-Tuning Control Algorithm to a Hydraulic Test Rig

1987 ◽  
Vol 201 (4) ◽  
pp. 285-295 ◽  
Author(s):  
S Daley
Keyword(s):  
Natural Frequency ◽  
Control Algorithm ◽  
Measurement Noise ◽  
Time Varying ◽  
Test Rig ◽  
Hydraulic Test ◽  
System Parameters ◽  
Self Tuning ◽  
Tuning Process ◽  
Selection Of

The application of a fast self-tuning controller to a hydraulic test rig having a predominant natural frequency of the order of 20 Hz is described. The controller is shown to perform well despite the presence of non-linearities, measurement noise and load disturbances. Time-varying system parameters are rapidly compensated for and only minor transients are introduced by the tuning process. A method for assisting the selection of the parameters required for successful self-tuning controller implementation is also demonstrated.

Time-varying filters for ISAR motion compensation

1998 ◽  
Author(s):  
Gabriel Thomas ◽  
Benjamin C. Flores
Keyword(s):  
Motion Compensation ◽  
Time Varying

scholarly journals Dynamics modeling and analysis of feed drive system for a frame saw machine considering time-varying load

2021 ◽  
Vol 22 ◽  
pp. 26
Author(s):  
Depeng Sun ◽  
Jinsheng Zhang
Keyword(s):  
Natural Frequency ◽  
Velocity Fluctuation ◽  
Natural Frequencies ◽  
Removal Rate ◽  
Drive System ◽  
Parameter Method ◽  
Dimension Stone ◽  
Time Varying ◽  
Feed Drive ◽  
Feed Drive System

Frame saw machine is one of machine tools that is used to process dimension stone. The velocity fluctuation of traditional feed drive system (FDS) lead to excessive wear of diamond particles. The dynamic performance of the FDS has time-varying characteristics during the processing of stone with a large material removal rate. In this paper, a novel FDS was proposed. Firstly, the dynamic modeling of FDS was set up on account of lumped parameter method (LPM). Then the speed of the new FDS was compared with that of the traditional FDS. Finally, the frequency response characteristics of the system were solved by Lagrange and state space method. Results showed that the new FDS has a faster response feed and less velocity fluctuation. The natural frequency and the amplitude of acceleration increase with decreasing load. With the time-varying load, the range of the second-order natural frequency increased by 50 Hz, which was larger than that of the first-order. The modal test verified that the first two natural frequencies of the saw blade are within the range of the natural frequencies of FDS. The proposed FDS can guide for design, reduce the wear of diamond, and improve processing quality.

scholarly journals Learning Input Shaping Technique for Non-LTI Systems

1998 ◽  
Vol 123 (2) ◽  
pp. 288-293 ◽  
Author(s):  
Juyi Park ◽  
Pyung-Hun Chang
Keyword(s):  
Natural Frequency ◽  
Closed Loop ◽  
Industrial Robot ◽  
Loop System ◽  
Input Shaping ◽  
Time Varying ◽  
Closed Loop System ◽  
Shaping Technique ◽  
Time Varying Systems

It is well known that conventional Input Shaping Technique (IST) is not very effective in suppressing residual vibrations for non-LTI systems, such as substantially nonlinear or time-varying systems. In an effort to increase the effectiveness such systems, this paper presents Learning Input Shaping Technique (LIST) which iteratively updates the parameters of IST from previous trials. Simulations are presented for four different cases: (1) when the natural frequency or damping of a system is not estimated well; (2) when a system has time varying vibration; (3) when a system has nonlinear flexibility; and (4) when a closed-loop system includes a saturation element in the loop. LIST is experimented on a six D.O.F industrial robot to evaluate its effectiveness. The results of the simulations and the experiment show that the residual vibrations become considerably smaller as iteration goes on, thereby demonstrating the effectiveness of LIST.

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