scholarly journals Adaptive Active Vibration Control for Machine Tools with Highly Position-Dependent Dynamics

2018 ◽  
Vol 12 (5) ◽  
pp. 631-641 ◽  
Author(s):  
Robin Kleinwort ◽  
◽  
Jonathan Platz ◽  
Michael F. Zaeh
Keyword(s):  
Vibration Control ◽  
Machine Tools ◽  
Material Removal ◽  
Control Strategies ◽  
Active Vibration Control ◽  
Adaptive Controller ◽  
Depth Of Cut ◽  
Removal Rates ◽  
Active Vibration ◽  
Free Material

The material removal rates of machine tools are often limited by chatter, which is caused by the machine’s most flexible structural modes. Active vibration control systems mitigate chatter vibrations and increase the chatter free axial depth of cut. However, model-based control strategies reach their limit if the machine tool exhibits highly position-dependent dynamics. In this paper, an adaptive control strategy is presented. This strategy uses online system identification to adapt the controller. The adaption algorithm is mainly automated. However, a few parameters still need to be selected. Therefore, a methodology for the determination of the optimal parameters is proposed. The adaptive controller was implemented on a B&R PLC and its suitability was verified experimentally by the observation of notable increases in the chatter-free material removal rates.

Simulation-Based Dimensioning of the Required Actuator Force for Active Vibration Control

2018 ◽  
Vol 12 (5) ◽  
pp. 658-668 ◽  
Author(s):  
Robin Kleinwort ◽  
◽  
Philipp Weishaupt ◽  
Michael F. Zaeh
Keyword(s):  
Machine Tool ◽  
Vibration Control ◽  
Machine Tools ◽  
Active Vibration Control ◽  
Depth Of Cut ◽  
Force Model ◽  
Machining Processes ◽  
Simulation Based ◽  
Active Vibration ◽  
The Right

The material removal rates of machine tools are often limited by chatter, which is caused by the machine’s most flexible structural modes. Active vibration control systems mitigate chatter vibrations and increase the chatter-free depth of cut. The systems can be used for already-in-use machine tools in particular as a retrofit solution. Unfortunately, no dimensioning techniques exist to help in finding the right actuator size required for a specific machine tool. This publication presents a simulation-based dimensioning methodology that determines, based on a stability analysis, the required actuator force and bandwidth. First, the critical machining processes, based on machine tool specific parameters, are identified. Then, the required actuator force and bandwidth are determined with the help of a coupled simulation model that consists of a cutting force model, the machine’s structural dynamics, and a model of the active vibration control system.

Multivariable control of active vibration compensation modules of a portal milling machine

2016 ◽  
Vol 24 (1) ◽  
pp. 3-17 ◽  
Author(s):  
Christian Brecher ◽  
Marcel Fey ◽  
Birk Brockmann ◽  
Prateek Chavan
Keyword(s):  
Vibration Control ◽  
Machine Tools ◽  
Test Bench ◽  
Dynamic Behaviour ◽  
Active Vibration Control ◽  
Depth Of Cut ◽  
Milling Machine ◽  
Modal Parameter ◽  
Cutting Depth ◽  
Active Vibration

The Z-ram of a Portal Milling machine presents a weak point in the dynamic behaviour of the machine tool which makes it prone to the occurrence of chatter vibration. Since chatter vibrations directly limit the maximum allowable cutting depth during machining, an improvement in dynamic behaviour of the machine tools by means of active vibration control of the spindle will result in an increase of maximum cutting depth. An active vibration control of the Tool Center Point of a Portal Milling machine using four hydraulic compensation modules integrated in the Z-ram structure is proposed. A test bench for the Z-ram was constructed at Machine Tools Laboratory (WZL) of RWTH Aachen University and it’s modal analysis revealed the occurring dominant vibration mode. A polyreference-LSCF modal parameter estimation was employed for identification of the measured MIMO Frequency Response Functions (FRF) of the Z-ram test bench. Using this mathematical model, the MIMO controller was synthesized with the Glover-McFarlane [Formula: see text] Loop Shaping Design procedure. The implementation of the controller on the test bench resulted in significant improvement in the compliance behaviour of the Z-ram structure. The dynamic compliance at dominant mode of vibration at 75 Hz was reduced by a factor of 3.5. Furthermore, the attenuation of the maximum negative real part resulted in a direct increase in maximum stable depth of cut by a factor of 2.1.

scholarly journals Experimental implementation of artificial neural network-based active vibration control & chatter suppression

2021 ◽  
Author(s):  
Yong Xia
Keyword(s):  
Neural Network ◽  
Neural Networks ◽  
Artificial Neural Network ◽  
Control System ◽  
Vibration Control ◽  
Control Strategies ◽  
Active Vibration Control ◽  
Chatter Suppression ◽  
Active Vibration ◽  
Artificial Neural

Vibration control strategies strive to reduce the effect of harmful vibrations such as machining chatter. In general, these strategies are classified as passive or active. While passive vibration control techniques are generally less complex, there is a limit to their effectiveness. Active vibration control strategies, which work by providing an additional energy supply to vibration systems, on the other hand, require more complex algorithms but can be very effective. In this work, a novel artificial neural network-based active vibration control system has been developed. The developed system can detect the sinusoidal vibration component with the highest power and suppress it in one control cycle, and in subsequent cycles, sinusoidal signals with the next highest power will be suppressed. With artificial neural networks trained to cover enough frequency and amplitude ranges, most of the original vibration can be suppressed. The efficiency of the proposed methodology has been verified experimentally in the vibration control of a cantilever beam. Artificial neural networks can be trained automatically for updated time delays in the system when necessary. Experimental results show that the developed active vibration control system is real time, adaptable, robust, effective and easy to be implemented. Finally, an experimental setup of chatter suppression for a lathe has been successfully implemented, and the successful techniques used in the previous artificial neural network-based active vibration control system have been utilized for active chatter suppression in turning.

Distributed active vibration cooperative control for flexible structure with multiple autonomous substructure model

2020 ◽  
Vol 26 (21-22) ◽  
pp. 2026-2036
Author(s):  
Xiangdong Liu ◽  
Haikuo Liu ◽  
Changkun Du ◽  
Pingli Lu ◽  
Dongping Jin ◽  
...  
Keyword(s):  
Vibration Control ◽  
Cooperative Control ◽  
Vibration Suppression ◽  
Control Strategies ◽  
Active Vibration Control ◽  
Flexible Structures ◽  
Lyapunov Theory ◽  
Sensors And Actuators ◽  
Active Vibration ◽  
Distributed Cooperative Control

The objective of this work was to suppress the vibration of flexible structures by using a distributed cooperative control scheme with decentralized sensors and actuators. For the application of the distributed cooperative control strategy, we first propose the multiple autonomous substructure models for flexible structures. Each autonomous substructure is equipped with its own sensor, actuator, and controller, and they all have computation and communication capabilities. The primary focus of this investigation was to illustrate the use of a distributed cooperative protocol to enable vibration control. Based on the proposed models, we design two novel active vibration control strategies, both of which are implemented in a distributed manner under a communication network. The distributed controllers can effectively suppress the vibration of flexible structures, and a certain degree of interaction cooperation will improve the performance of the vibration suppression. The stability of flexible systems is analyzed by the Lyapunov theory. Finally, numerical examples of a cantilever beam structure demonstrate the effectiveness of the proposed methods.

scholarly journals Active vibration control for a CNC milling machine

2013 ◽  
Vol 228 (2) ◽  
pp. 230-245 ◽  
Author(s):  
DG Ford ◽  
A Myers ◽  
F Haase ◽  
S Lockwood ◽  
A Longstaff
Keyword(s):  
Control System ◽  
Tool Wear ◽  
Machine Tool ◽  
Vibration Control ◽  
Surface Finish ◽  
Machine Tools ◽  
Active Vibration Control ◽  
Milling Machine ◽  
Cnc Machine ◽  
Active Vibration

There is a requirement for improved three-dimensional surface characterisation and reduced tool wear when modern computer numerical control (CNC) machine tools are operating at high cutting velocities, spindle speeds and feed rates. For large depths of cut and large material removal rates, there is a tendency for machines to chatter caused by self-excited vibration in the machine tools leading to precision errors, poor surface finish quality, tool wear and possible machine damage. This study illustrates a method for improving machine tool performance by understanding and adaptively controlling the machine structural vibration. The first step taken is to measure and interpret machine tool vibration and produce a structural model. As a consequence, appropriate sensors need to be selected and/or designed and then integrated to measure all self-excited vibrations. The vibrations of the machine under investigation need to be clearly understood by analysis of sensor signals and surface finish measurement. The active vibration control system has been implemented on a CNC machine tool and validated under controlled conditions by compensating for machine tool vibrations on time-varying multi-point cutting operations for a vertical milling machine. The design of the adaptive control system using modelling, filtering, active vibration platform and sensor feedback techniques has been demonstrated to be successful.

scholarly journals INVESTIGATION OF LOCAL AND MODAL BASED ACTIVE VIBRATION CONTROL STRATEGIES ON THE EXAMPLE OF AN ELASTIC SYSTEM

2019 ◽  
Vol 19 (2) ◽  
pp. 32-45 ◽  
Author(s):  
Christoph PEUKERT ◽  
Patrick PÖHLMANN ◽  
Marcel MERX ◽  
Steffen IHLENFELDT ◽  
Jens MÜLLER
Keyword(s):  
Vibration Control ◽  
Machine Tools ◽  
Degrees Of Freedom ◽  
Elastic System ◽  
Control Strategies ◽  
Active Vibration Control ◽  
Modal Control ◽  
Control Approach ◽  
Control Loops ◽  
The Impact

Nowadays, feed axes are often equipped with multiple parallel-acting actuators in order to increase the dynamics of the machine tool. Also, additional actuators for active damping are widely used. Normally, the drives or actuators are controlled independently without consideration for the impact on each other. In contrast, by using the modal space control, the system can be decoupled and the modal control loops can be adjusted independently. This control approach is particularly suitable for motion systems, such as machine tools, which have more drives or actuators than degrees of freedom of movement. This paper deals with the pre-investigation of the modal-based vibration control for machine tools with additional actuators. The object of investigation is an elastic system with a movable saddle. The modal-based control is compared with a local control approach. The results obtained experimentally on the test rig are presented. The modal control is superior since, with the modal approach, each control loop corresponds to a specific vibration mode, and the control law for this loop is designed to provide the desired performance of the control system at the corresponding resonance frequency. The parameterisation of the control loops is simplified by modal control, since the modes can be controlled independently.

An adaptronic approach to active vibration control of machine tools with parallel kinematics

2008 ◽  
Vol 3 (2) ◽  
pp. 207-215 ◽  
Author(s):  
Alexandra Ast ◽  
Steffen Braun ◽  
Peter Eberhard ◽  
Uwe Heisel
Keyword(s):  
Vibration Control ◽  
Machine Tools ◽  
Active Vibration Control ◽  
Parallel Kinematics ◽  
Active Vibration

Evolutionary adaptive active vibration control

1997 ◽  
Vol 211 (3) ◽  
pp. 183-193 ◽  
Author(s):  
M A Hossain ◽  
M O Tokhi
Keyword(s):  
Vibration Control ◽  
Control Mechanism ◽  
Vibration Suppression ◽  
Active Vibration Control ◽  
Adaptive Controller ◽  
Recursive Least Squares ◽  
Flexible Beam ◽  
Beam Structure ◽  
Comparative Performance ◽  
Active Vibration

This paper presents an investigation into the development of an adaptive active control mechanism for vibration suppression using genetic algorithms (GAs). GAs are used to estimate the adaptive controller characteristics, where the controller is designed on the basis of optimal vibration suppression using the plant model. This is realized by minimizing the prediction error of the actual plant output and the model output. A MATLAB GA toolbox is used to identify the controller parameters. A comparative performance of the conventional recursive least-squares (RLS) scheme and the GA is presented. The active vibration control system is implemented with both the GA and the RLS schemes, and its performance assessed in the suppression of vibration along a flexible beam structure in each case.

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