Mechatronics By Ching .J. Xang

(University of Xheng, China)

INDEX:-

Definition of Mechatronics

Mechatronic systems in machine tools

Mechatronics in CHAMELEON

Magnetic levitation spindle

Axis on axis

Vibration aided machining

Rapid calibration

Active error compensation

Active filtering

Active damping

Adaptronic workholding

Books on Mechatronics

Journals on Mechatronics

Papers on Mechatronics

Other resources: MINOS Project

Definition of Mechatronics

The original definition for Mechatronics was done by Yaskawa Electric Company in this way:

The word Mechatronics is composed of 'mecha' from mechanism and 'tronics' from electronics. In other

words, technologies and developed products will be incorporating electronics more and more into

mechanisms, intimately and organically, and making it impossible to tell where one ends and the other

begins.

The concept of Mechatronics has evolved since its first definition (early 80s), and now it includes a

broader concept integration more than just mechanisms and electronics. A representative definition can

be the one proposed by the Journal of Mechatronics:

Mechatronics is the synergistic combination of precision mechanical engineering, electronic control and

systems thinking in the design of products and manufacturing processes. It relates to the design of

systems, devices and products aimed at achieving an optimal balance between basic mechanical

structure and its overall control.

Even though many people believe that the presence of mechanical, electrical, electronic components,

and computers make a system mechatronics, others do not feel the same as there is nothing wrong with

the individual identity. Hence, the term mechatronics should be used to represent a different meaning,

namely, a design philosophy, where mechanical, electrical, electronics components, and IT should be

considered together in the design stage itself to obtain a compact, efficient, and economic product

rather than designing the components separately.

Mechatronic systems in machine tools

The main mechatronic components of machine tools include in particular the main and feed drives,

with inclusion of motors, sensors and control systems.These components and their integration in terms

of information technology define the capability of the actuators and the bandwidth of the solution

initiatives. Major progress can be expected as a result of optimum system integration, but the

limitations of stiffness, weight and damping of the current materials give rise to systems that might not

be able to reach the required performance levels.

Nowadays, more and more active systems find application in machine tools in order to increase

accuracy and cutting performance. In many cases, the overall performance of the machine tool is

increased by the compensation of the occurring deformations. In contrast to passive systems, external

energy is fed into the machine with the help of active systems to improve the system behaviour.

The active systems offer the possibility to influence the machining process due to their additional

degrees of freedom. E xisting active systems can be divided into two main groups. Firstly, many of the

existing approaches can be categorized as mechatronic approaches. A consequent development of

mechatronic approach is the so-called adaptronic approach . In the following figure these both

approaches are compared with the conventional passive structure.

The response of a passive structure is determined by the mass, stiffness and damping of the system. The

mechatronic systems are characterized by four individual functions of the entire system - in particular

the passive structure, the sensor, the actuator and the control. These elements are placed physically

close together but are functionally not integrated. The main advantage of a mechatronic system is the

capability to capture the external disturbances and enable compensation with the help of the integrated

actuators. Additional costs for the actuators and sensors as well as the control system are disadvantages

of these systems.

The term "Adaptronic" designates the integration of at least two separately arranged functions used in

the mechatronic approach into one functional unit. Due to the use of multifunctional materials and the

simultaneous use of their properties, additional elements can be saved. As an example the actuator-

sensor integration of piezoelectric actuators or shape memory alloys can be mentioned.

Mechatronics in CHAMELEON

CHAMELEON project makes use of mechatronics for several applications.

Magnetic levitation spindle

A sophisticated control system based in the measurement of the radial and axial positions of the shaft

and actuation through magnetic coils provides a fully levitating system. Levitation avoids friction at the

bearings, and consequently higher rotational speeds can be reached.

Measurement of displacements and knowledge of the applied forces at the bearings can be the basis for

further developments, for example to estimate cutting forces and to set collision alarms, tool unbalance,

wear and breakage signals, or adaptive control.

Axis on axis

The clearance at the magnetic bearings, though being limited, can be used to compensate for the

following errors of the displacement axes. The bandwith of the displacement axes being limited, mainly

due to the large moving masses to be moved, at high acceleration trajectories the following errors are

relatively large. A control system tending to compensate for these errors by applying small

displacements at the spindle gives rise to a system behaviour with a much larger equivalent bandwith, in

the order of the bandwith of the magnetic spindle bearings.

The required displacements are in the order of 0.1 mm, which can be produced by the magnetic

bearings.

Vibration aided machining

When machining hard materials, it has been proved that a high frequency vibration at the tool gives rise

to a reduction of the cutting forces and of the wear of the tool. Also, it helps reduce the tendency of the

part material to crack.

A tool holder able to add high frequency vibration to the tool is being developed in the project. The

system can be used on any machine with very little adaptation, avoiding the need to use specific

machines for this purpose.

Rapid calibration

Machine tools can loose positioning precision due to reasons like thermal deformation, own weight

forces, slideways errors, etc.

A system for absolute position calculation will be developed, so that it will be possible to get rid of

positioning errors. The system is based on obtaining the interference pattern of two spherical light

waves, and can be used as a way to calibrate the machine 'out of process', or even to obtain 'in process'

errors, due to thermal deformations for example.

Active error compensation

Two mechatronic applications are developed. One consists of an axis on axis system by piezoelectric

actuators. It will be able to compensate for trajectory errors and to provide damping to the system, thus

helping avoid chatter vibration. The other one will have strong force actuators able to distort the

structure in a way so as to compensate for static deformations and, at the same time, provide damping

to it.

Active filtering

This application will modify the position feed back signals by means of active, adaptative filters, to help

stabilise the position loop and increase its bandwith. It is an electronic / informatic application that will

help compensate for mechanical problems at the system.

Active damping

Chatter is one of the main concerns when performing roughing operations. The system to be developed

will analyse vibration signals and provide vibration damping forces by means of magnetic actuators. The

cutting capacity of the machine without chatter vibration is augmented several times. Adaptronic

workholding

The complete system will consist of a photogrametric application to characterise the actual shape of the

raw part and calculate its correct position at the machine. A vision based system will recognise the

actual position of the part, and intelligent fixtures, including displacement and force sensors, as well as

electrical actuators, will correct the position of the part without applying distorting forces into it.

Books on Mechatronics

Mechatronics, an integrated approach , by Clarence W. de Silva, gives a very broad insight on the different aspects of mechatronics.

Mechatronics, electronics control systems in mechanical and electrical engineering , by W Bolton, also

gives insight to almost all the technologies involved in mechatronics, including sensors and signal

conditioning, actuators of several types (electrical, pneumatical, hydraulica, mechanical, system models,

dynamic response and transfer functions of systems, controllers, digital logic, etc.)

Mechatronics, an introduction , by Robert H. Bishop. Again, a very broad presentation of technologies

involved in mechatronics.

Journals on Mechatronics

Mechatronics: The Science of Intelligent Machines

A Journal of IFAC, the International Federation of Automatic Control

Journal of Robotics and Mechatronics (JRM)

There are plenty of journals on mechatronics and robotics in Japan, however, they are all written in

Japanese language so that a few of them have contributed for increase in universal funds of knowledge.

Thus both Japanese and overseas researchers have failed in exchange of their knowledge on robotics

and mechatronics. "JRM" is published to cope with this problem.

Mechatronics Zone Online Magazine

The latest mechatronics news, trends, technologies, and applications for multidisciplinary design

engineers.

IEEE/ASME Transactions on Mechatronics

A joint publication of IEEE Industrial Electronics Society, IEEE Robotics and Automation Society and

ASME Dynamic Systems and Control Division.

Papers on Mechatronics

Mechatronic Systems for Machine Tools

R. Neugebauer, B. Denkena, K. Wegener

This paper reviews current developments in mechatronic systems for metal cutting and forming

machine tools. The integration of mechatronic modules to the machine tool and their interaction with

manufacturing processes are presented. Sample mechatronic components for precision positioning and

compensation of static, dynamic and thermal errors are presented as examples. The effect of modular

integration of mechatronic system on the reconfigurability and reliability of the machine tools is

discussed along with intervention strategies during machine tool operation. The performance and

functionality aspects are discussed through active and passive intervention methods. A special emphasis

was placed on active and passive damping of vibrations through piezo, magnetic and electro-hydraulic

actuators. The modular integration of mechatronic components to the machine tool structure,

electronic unit and CNC software system is presented. The paper concludes with the current research

challenges required to expand the application of mechatronics in machine tools and manufacturing

systems.

Robust Chatter Reduction In Centerless Grinding Machines By Active Damping

I. Egaa, X. Sabalza, 2005

The use of active feedback compensation to mitigate cutting instabilities in the Estarta 327 MDA

centerless grinding machine is presented. An active damping system reduces machining regenerative

vibrations -chatter- that constitute a restrictive bound within the trade-off between surface quality and

productivity. In this paper, a robust design is presented including performance specifications as regards

robust stability, control effort constraint, and sensitivity performance.

Beyond intelligent manufacturing: A new generation of flexible

intelligent NC machines

S. Mekid, P. Pruschek, J. Hernandez, 2008

New challenges for intelligent reconfigurable manufacturing systems are on the agenda for the next

generation of machine tool centres. Zero defect workpieces and just-in-time production are some of the

objectives to be reached for better quality and high performance production. Sustainability requires a

holistic approach to cover not only flexible intelligent manufacture but also product and services

activities. New routes philosophy of possible machine architecture with characteristics such as hybrid

processes with in-process inspection and self-healing will be presented with great features as well as

challenges related to various aspects of the next generation of intelligent machine tool centres.

Simulation of an active vibration control system in a centerless

grinding machine using a reduced updated FE model

H. Fernandes, I. Garitaonandia, J. Albizuri, J.M. Hernndez and D. Barrenetxea, 2008

In this paper, a novel and complete process to simulate an active vibration control system in a centerless

grinding machine is presented. Based on the updated finite element (FE) model of the machine, the

structural modifications performed to incorporate active elements are detailed, as well as the

subsequent reduction procedure to obtain a low-order state space model. This reduced structural model

was integrated in the cutting process model giving a tool adapted for the purpose of simulating different

control laws. Using the developed model, a control algorithm, which previously had been implemented

in the centerless grinding machine under study, was checked. The simulation results were in agreement

with the experimentally obtained ones, showing that the designed model is able to reproduce machine

behaviour with the control activated. This model constitutes a powerful tool to evaluate the

effectiveness of different approaches to that of the described one, making it possible to tackle an

optimisation process of the control system by means of simulations and, thus, avoiding the costs that

would involve the practical implementation of each one.

Optimization of Multiple Tuned Mass Dampers to Suppress Machine

Tool Chatter

J. Muoa, Y. Yiqing, Y. Altintas, 2010

Chatter is more detrimental to machining due to its instability than forced vibrations. This paper

presents design and optimal tuning of multiple tuned mass dampers (TMDs) to increase the chatter

resistance of machine tool structures. The chatter free critical depth of cut of a machine is inversely

proportional to the negative real part of the frequency response function (FRF) at the tool-workpiece

interface. Instead of targeting to reduce the magnitude, the negative real part of the FRF of the machine

is reduced by designing single and multiple TMD systems. The TMDs are designed to have equal masses,

and their damping and stiffness values are optimized to improve chatter resistance using minimax

numerical optimization algorithm. It is shown that multiple TMDs need more accurate tuning on the

stiffness and natural frequency of each TMD, but are more robust to the uncertainties in the damping

and input dynamic parameters in comparison to single TMD applications. The proposed tuned damper

design and optimization strategy is experimentally illustrated to increase chatter free depth of cuts.

Mechatronics: From The 20th To 21st Century

M. Tomizuka, 2002

This paper presents a Year-2000 (Y2K) status report of mechatronics. The Y2K denition of mechatronics

is ''the synergetic integration of physical systems with information technology and complex-decision

making in the design, manufacture and operation of industrial products and processes.'' Mechatronics

may be interpreted as the best practice for synthesis of engineering systems, and it covers a broad area

and scope. Vehicle lateral control for automated highway systems, hard disk drives and media handling

mechanisms for printing engines are reviewed as examples of mechatronics research. Engineering

students should be exposed to mechatronics and to the culture of working in teams. r 2002 Elsevier

Science Ltd. All rights reserved.

Other resources: MINOS Project

MINOS Project: European Concept for the additional Qualification Mechatronic of skilled Personnel in

the globalized industrial Production.

MINOS developed a modular CBT-supported further education concept for non-graduates in Hungary,

Poland, Germany and Sweden. The didactic teaching material and teaching modules for modular

training are prepared in English, German, Polish and Hungarian languages. The modular structure makes

the adaptation of different initial situations in these countries possible. The material includes 8 modules,

which comprise mathematical fundamentals, technological problems and soft skills. As result we have a

multi-language learning and teaching system with a modular structure, which allows achieving a cross-

national comparability of the obtained academic degree in the field of mechatronics, with the possibility

for other countries to join.