1.1E mergence of Mec hatronic Serv oS ystems 5 as faraspossible.Thatistosay ,the motormust be selected from the clearly discussed results on thenecessary maximaltorquefor executing op eration.Inaddition, the size of continuouslymixed disturbance must be belowthe continuous rated torque of motor. 5. In manyservosystems, afeedbacksystem can be only established based on theinformation of servoactuator, butnot according to the information of eachmoveable tipormotion tip. It meansthat, the detectorofposition andvelocityinthe opposite loadside of motor(side without load) is installed and thenthe feedback system of actuatorcontrol is resembled by the obtained information. This kind of con trol system is called as emi- closed lo op. Generally ,i ti sv ery difficult to construct the feedbac ks ystem by motiontip informationinmanymechanism machines. The structureof afull-closedlooponthe feedback of moveable tipinformation adoptedin some parts is shown in Fig.1.3. In addition, almost all mechanic structures of industrial six-freedom degree robots are semi-closed loop. The relation with servoactuator is briefly shown in Fig.1.4. The structureofthis kind of semi-closed loop cannotbeobtainedinthe mechatronic servosystem as same as the general feedbacksystem. Fortaking into account the system as same as the general feedbacksystem, the condition is that the system should be rigidlyunifiedwith the actuatorwhen mechanismiswithin the control region according to the desired motioncommand. 6. Theactuator installed in the mechanism structured for multi-axis move- able mechanismgener ally corresponds to the forward motionofone actua- toraswell as rotationofone axis(freedomdegree). The arbitrary curve in three-dimensional space implemented by simultaneous control of multiple axes is given in aservosystem as the command of time function about the position for desired motionineachindependent axis. Theprecondi- tion in control system is that axisisregarded as independence. In fact, for example, in the case of amulti-axisrobot arm, thereactionofone axis motion affectsother axes, i.e., axis interference occurs. This axis interfer- ence is very important when tryingtominimize it in mechanism design. Moreover, in amechatronic servosystem, when considering one axis, the effect fr om other axes duetoits reaction is regarded as the disturbance. D e t e c t o r Actua t o r M e c h a nis mpa rt U pper c ontroller S e rvodr i v e r Fig. 1.3. Structure of industrial servosystem 61 Outline of Mec hatronic Serv oS ystems Fig. 1.4. Structure of industrial robot and arrangementofactuator And forreducing the effect in control to aminimum, the motionofaxis should be changed as be capable of independence. 7. The generationofobjectivereference input for realizing mechanism move- mentstructured with amulti-axismechanism is by the servosystem in whichthe independentmotion of eachaxis includingintro ducedmachine mech anismc an be realized. The featureso fr eference input is regulated for keepin gthe consistenceofeachaxis. In almost all cases, position control system is regarded as a1st order system. The feedforward gain should be iden tical. If regulating lik et his,i ti sv ery easy to implemen tt he algorithm of referenceinput generation to amulti-axisservosystem for anyspatial curve. 8. Fo rr ealizing an arbitrary curve in three-dimensional space, in most of cases,the curveisapproximatedbyafoldedline. As its results, the refer- ence input to eachaxis servosystem is renewed in eachgiven co ordin ate po in ta nd the ramp input with va rious slop ea nglesi sg iv en con tin uously . The velocityofeachaxis is calculated for making the given synthetic velocityasadesiredvelo city. In addition, in the case of performing the acceleration/deceleration control at start/stop point, the reference input for simultaneous start/stop of all axes, i.e., same command to eachaxis at acceleration/decelerationpoint, is generated. 9. Thedata regarded as objective referenceinput to servosystem from the uppercontrol device, suchascomputerorspecial control, should be given according to the designatedperiod(designatedtime interval). Therefore, the reference input for serv os ystem is describ ed with the form of av elo cit y 1.2I ssues in Mec hatronic Serv oS ystems 7 command.Here, the periodofthis commandortime interval is called as the system clock of theservosystem in the controller or servodata rate of thecontroller.Since this reference time interval is selected based on the prop ertyofthe servosystem dependentonthe mechanismpartstructure and related with the capabilityofcontrol devise, itsvaluerepresents the synthetic performance of amachine.Inthe numerical control device of aworking machine, several [ms] as well as ten and several or several ten times [ms] are adopted. The knowledge of industrial expects cannot be understood definitely. Therefore, so far, the theoretical analysisonthe properties of thecontrol system structure, as we ll as the va rious prope rties of mech atronic serv os ys- tem taking into accountits utilization, as above,cannotbefound. Forthis purpose ,inthis book, stepping on theutilizationofmechatronic servosystem, various adoptedcontrol methodsand realizedcontrol performancesbythese methods are firstly discussedtheoreticallyorarguably as themain point, and then the discussion on the developmentinthe future is added. 1.2Issues in Mechatronic ServoSystems In or der to understand the current mechatronic servosystem and develop serv os ystems with be tter pe rformance thana tp resen t, thiss erv os ystem must be investigated from various points of view. The discussion points are listed as below. 1. Modelin gofamechatronic servosystem 2. Performance of oneaxis in amechatronic servosystem 3. Performance of multiple axes in amechatronic servosystem 4. Command to servosystem The above viewpoints come from the system components of servosystem in theory.Itmeans that aservosystem is one of the system components for es- tablishingamechanism machineand needed to knowthatinwhichstep servo system can be thoughtasgood enough so that the system is constructed effi- ciently,desired mechanism as well as performancesisrealized, etc. Therefore, the description sequence of subsequentchapters is different fromthe expla- nation sequence in this chapter. Each section is divided by the items listed above. 1.2.1 Discussion on ModelingofaMechatronicServoSystem From theview of usingthe model of mechatr onic servosystem, this model should be dividedintotwo points. One is the model with the servosystem not only taking into accountthe mechanismstructurebut alsothe load.Another is the mo del comb iningt he mo deled mech anisms tructurea nd serv os ystem. 81 Outline of Mec hatronic Serv oS ystems Forthe mechanismperforming orthogonal motion, various discussionscan be carried out only by the former modeling. But for the machineasanarticulated robot, the latter modelingisalso necessary. (1) Modelingofthe Overall MechatronicServoSystem In the mechatronic servosystem adopted in anymechanism, suchasanumeri- cal control working machine, industrial robot, etc., representing the ind ustr ial mechanism machine, the propertyofprevious or presentservosystem can be expressed by K p .Ingeneral, the value of K p is the high rigid of huge ma- chine. In the general rotation plate, machinecenter, etc, the value of K p is 35–40[1/s]. In an industrial robot, the value of K p is 15[1/s]. It is naturally the most simple approximation1st order system in control system. However, concerning the mechatronic servosystem, it should be considered whichcon- ditions must be satisfied in its internal structure, and additionally,itisnearly not clear about the usageconditionofthis 1st order delay system. Actually,if the maximalspeed used in this machineisabout 1/10 speedregion, this ap- proximationcan model the whole system quite well. However, if it is number for one speed, it will have big deviation with theactual system. In analyzing the currentservosystem, the mechanism is thoughttocom- bine with shaft of motor whichisasrigid. Under this pr econdition, the servo motorfor adriving mechanismisselected. The control parameter regulation of suchaservosystem is also followingthis consideration.Therefore, the 1st order approximation with preconditionispursuedtobeclarified [4 ] .However, in fact,itisdifficult to satisfy this precondition duetovariousrestraints. High-speed and high-precision motionofmechatronics machines has been the objectiveinrecentyears. Forfinding outthe controlstrategy,itisrequired to mo del con trol system correctly . Concerning about this problem, it is explained in 2.1 and 2.2. (2) Mo delingo fa Multi-Join tedR ob ot Generally, in the multi-jointed industrial robot, orthogonal motion(in working coordinate)data is generatedbyusing coordinate calculationbasedoninverse kinematics.B yt he serv os ystem for join ta ngle cont rol( in join tc oo rdinate), the motion can be realizedinworking coordinate system as theorthogonal co- ordinate system.The inverse kinematics calculation of orthogonal coordinate va lue is pe rformeda te ac hr eference input time in terv al. When given two points for performing orthogonal motion,with high-speed motion, the phenomenon of deviation of several millimeters in the motion trajectory of the line between two points is apparent. The motionvelocityof this time is about 1[m/s]. The reference input time interval of robot controller is generally adopted with about 20[ms]. This velocityislowerthanthe velocity of appearing centrifugal force rated with two times velocityfor general issue or collision ratedwith two axesvelocityintegral. Ther efore, the trajectory 1.2I ssues in Mec hatronic Serv oS ystems 9 deviation is difficulttoconsider basedontheseeffects. But if lengthening the reference input time interval or whether or not orthogonal motionhappening, severalreasons should be considered. When the velo cityofpresentcontourcontrol is below25[m/min], the tra- jectory deviation does notoccur.Therefore, in the controlbasedonthe previ- ousposition decisioncontrol concept, the trajectory precisioncan be required. In the position decision control, the motion with the highest velocityallowed by this robot can be performedinalmost all cases. In the actual examples of these kindsofapplication,suchashard-cutting,spot-welding, etc, the posi- tion va riation (tra jectory precision) is seve ral[ mm]. Recen tly ,t he follow ing is also required. In order to analyze the control strategy for satisfying these requirements, the correct modelingfor multi-jointed robot is needed. The relevantdetail description is given in section 2.3.The discussedmodeling combining the modelingofthe whole servosystem in the former part, the importance of modelingcontrol system in future mechanismmachinesisillustrated. 1.2.2Discussion on the Performance of One AxisinaMechatronic ServoSystem In ausual, mechatronic servosystem consists of multi-axis mechanism. When taking into accountthe performance of amechanism machine, the analysis on mu lti-axis serv os ystem mu st be carried out. Ho we ve r, the structure for thisactuator is basically independentfor oneaxis. Forthe basicfeature of amechatronic servosystem, the discussion based on the state of one axis structurei ss ufficient . Hence, thereare two problems on discrete time interval when analyzing the oneaxis performance of mechatronic servosystem. One is that the structureof curren tm ec hatronic serv os ystems are almost all soft wa re serv os ystems and they must be thoughtofcomi ng fromthe sampling controlsystems. Therefore, the data renewal time interval of control system is determined by sampling frequency .I ng eneral mec hatronic serv os ystem, theree xist same dela yt ime and 0th order hold with this time interval. Therefore, this time interval greatly affects the characteristicofclosed-loop control system. Another is that, the uppercontroller seen fromthe servosystem, i.e., the computerusing for internal trajectory calculationofthe controller, is per- formedinatime interval providingcommandgiven in the servosystem. From therelationbetween this time interval and performance of thecontrol system, theoverall mechatronic servosystem performance of amechatronic machine can be determined. From this pointofview, the value of these discrete time intervals are very important foranalyzing the performance of amechatronic servosystem. 10 1O utline of Mec hatronic Serv oS ystems (1)Proper Sampling Frequency In themiddle of 1980s, microprocessor (CPU), i.e., digital signal processor (DSP)became cheaper. These processors are equippedintoclosed-loop of servosystem. Hence, servosystem is constructed and movementcan be re- markably flexible. Software servosystems were developed. Theseservosystems were developed in thelaboratorybelonging to one of authors. From theexperiments, an experience rule, wasobtained. The eigen- value of position control system usingfor amechatronic machinebasedonthe realizedsoftware servofromthe analoguevelocityofacontrol device cannot be overabout 1/30 sampling frequency. Moreover, the velocitycontrol system is madebythe software servosystem and its insidecan be found similarwith the analogue pattern. The great difference herebetween the general sampling control system and the control system used in the mechanism machineisthe delay time. In the usually equippedpro cess control, comparing with the sampling time interval, theconsumedtime for working outthe state input andoperation value can be neglected. However, in the servosystem of amechanism machine, this cannot be successful. If the software servosystem adopted in amechanism machineisthe object of simulation, various unknown parts areclosed up.How to set the property of poweramplifier with PWM pattern,and howtocatchthe timing of state input andthe dynamicofoperation output canbeobtained. In general, in asoftware servosystem, avery big sampling frequency is adopted.Namely,under the restraintofhardwarecost,the maximalsampling frequencyisselected.Indetermining the sampling frequency by this way,the performance boundary of theservosystem when usingthis frequencyisnot distinct.Eventhoughexpecting to raise its performance,whichcomponentof control system should be improvedisalso unknown. In section 3.1,the quite simpleformofmechatronic servosystem wasana- lyzed. The relation between the performance of acontrol system andsampling time interval when considering the utilization situation of aservosystem was clarified. (2) Reference Input Time Interval When considering the characteris ticofamechatronic servosystem as intro- duced before, andregarding the loop structureofacontrol system about actuator above investigation of servosystem char acteristicasthe identical importantitem with its controller design, howtoprovide the commandto servosystem is aproblem. Thisproblemisabout the form of time functionof command.The problemofcommandcontaining the way of data given must be discussed. In the discussion of this commandsystem, with the currentcontroller structure, as theitem about the control performance of aservosystem, the 1.2I ssues in Mec hatronic Serv oS ystems 11 time intervalofgiven data to the servosystem through the interface from the uppercontroller is expected. Generally,inthe controller of themechanism machine, the data to the servosystem is given in adesignated period. This designatedperiodiscalled thereference input time interval. This is also called the (controller) system clock. This reference input time interval is discrete width as the data to the servo system. Within this interval, the command function of eachaxis is calculated. Then,this calculatedvalueisobtainedinthe servosystem with the state of zero order hold. From this,the motion of theservosystem generates velo city pe rio dic va riation reliedo nt his time in terv al andt ra jectory deterioration. Previously, the reference input time in terv al is obtained as the va lue rep- resenting the controller performance.Atpresent, in the newly developed con- troller,this value has the trendtobeminimal. However, dominatedbythe development of themicroprocessor, the desired performance is expected to be realizedwithout great cost. Therefore, the reasonable explanation of the relationship between this reference input time interval and various generated phenomenonisalmost non-existent. The competition of mechatronic product cost is rapidlyincreased. High performance is requiredmeanwhile keepingthe current situation. In this sit- uation, the performance of servodriver unit,the performance of theupper controller (reference input time interval, etc) as well as the characteristicof loadare analyzedcomprehensively.Bytaking these performancesobtained the balance whenobserving these performancesrespectively as the whole, it is very important to realize these desired performancescomprehensively.As the first stagefor analyzing them, fromthe view of theservosystem char- acteristicofone axis, thediscussion on the reference input time interval is carried out in section 3.2 and 3.3. (3) Quantization Error and ControlPerformance of Control System Thestructureofthe software servosystem wasdeveloped from only the po- sition controller software to both velocitycontroller andcurrentcontroller software, fromthe development of utilizedCPS, i.e.,DSP.Inthe construction of thecontrol system,high response performance is generallyrequired from its internal minor-loop. In the electric servosystem, currentfeedbackloopisthe inner-most loop.How resolution of currentdetection is expected for satisfying the required performance of servosystem is an important item to discuss in the stageofdesigning hardware constructing servosystem. As usual, although the control performancesabout the position and veloc- ityofthe servosystem were clear, the theoretical equationsfor expressing the designwhichthe controlperformance must be satisfied about its internal is unknown. In view of theconcretecircu it structure, the discussion of the item on quantizationerrorisformulated. However, the analysissolution on various in ternalp arameters relation to thec on trol system structure is ve ry difficult 12 1O utline of Mec hatronic Serv oS ystems to solve. Its difficulty would be estimated by taking into accountthe equation expression of poweramplifi er of PWM pattern.Fromthis pointofview, in almost all presentcases, thequantizationscale of control system internal, i.e., resolution is determined based on experience. Here, for the current(torque) loop of the motor, the most internal loop of mechatronic servosystem, the relationship between the necessary perfor- mance in the controlsystem and the resolution of currentdetection part is investigated. In order to clarify the main issue on considering the current structureofthe mechatronic servosystem, the foreseen whole control system is considered and the problems are form ulated. On these problems, is discussed in ch apter4 ,a ftera nalyzing the resolution of position detection firstly in section 4.1,the torque resolution is investigated in section 4.2.Fromthe formulation illustratedhere, the resolution of torque command considering velocityvariation ratioasacontrol performance is clear. According to thisresult, the necessityofidenticalprecisionwith the necessary resolution in currentdetection is clear. Moreover, in the case of zero-zoneof poweramplifier, i.e., nonlinear characteristic, it is easytoevaluate that the high resolution is necessary from the obtained results here. 1.2.3Discussion on the Performance of aMulti-AxisMechatronic Servo System The basic part of on discussion on mec hatronic serv os ystems can be carried out as aone-axisservosystem. However, wheninvestigatingthe performance of mechanismmachines, theymust be investigated as multiple axes. The mo- tion of mu lti-axis serv os ystems causing basic phenomena duet ot orques at- uration can be found. Whenusing aservosystem in the state of one axis, thereisalmost no problem in the induced phenomenon duetotorquesat- uration fromt he serv os ystem pe rformance po in to fv iew. Ho we ve r, if this phenomenon occursinthe multi-axis contour control, it will produce great effects on servosystem performance.Theseproblems arediscussed in section 5.1 and 5.2. (1) To rque Saturation Generally, in mec hatronic serv os ystems, the ratio of maximalt orquet hatc an be usedinratedtorqueand acceleration/deceleration is about1:3∼ 5. In actual servosystems, constantcoulombfriction frommotion resistance occupies a big part of rated torque when the servosystem is set into the mechanism. It means that, the opposite force in operation is regarded as the torque load. In order to allowthesetorques in thecontrol system when performing the movementalong astraightline, their values are reduced remarkably.Hence, in contour control, the servosystem must guarantee themovementalong the straightline. When clarifyin gthe application conditionofthe mechatronic system,i tm ust grasp that in whic hs cale torque reac hes saturationi nt he 1.2I ssues in Mec hatronic Serv oS ystems 13 state of capable motionofthe mechanismaswell as in whichdegree control performance deterioratesdue to torque saturation. Themechatronic servosystem design should select aservomotor forthe driving mechanisminmanycasesexcept the stageofresearch. Therefore, in servomotor selection,the velocityprofile (stage form) fordriving is designed andacceleration/decelerationaswell as constantmotion torquefor designated parameters (acceleration time,maximal velocity, etc) are calculated. In the mechatronic servosystem driven by the motorselected as above,itisalmost impossible to consider clearly the torque reflecting the actual adopted status. In section 5.1,fi rstly ,t he measuremen tm etho do ft orques aturation is show n. Basedo nt his metho d, the torque saturation of thea ctual mec hanism with the differentstatuses of asingle motorcan be known. Moreover, from graspingthe occurred phenomenon when existing torque saturationasinthe ab ove illustration, the reason of actual phenomena can be definitely judged. Foravoidingtorquesaturation naturally, the actuatorcapable of exporting torque with big capacity is needed to use. In reality, the correct motionis more importantthanchanging the ap plication method.For this purpose,itis necessary to knowthe simpleavoidance method, whichisdiscussed in section 5.2. (2) Master-Slave Synchronous PositioningControl Them aster-sla ve sync hronous po sitioning con trol metho di st he cont rolt hat must satisfy the ratio relationbetween the movementofone axisand that of another axisbetween two axes. This control is generatedfromthe motion pe rformance requiredi nt he tapping pro cess of them ac hining cent er. In the tappingprocess,the 1st axisisthe master axisofthe machiningcenter. This axis is moving as the control system performing startand stop forstageform driving installed in the rotational to ols.T he transfera xis as the second axis should be traced, namely synchronized. So then it performs aparallel move- mentasaposition control part. When the tapper, atoolfor standing tap forr otation mo ve men tk ept in the master axis, is rotated once, the transfer axis must be movedcorrectone pitch of thespring.Since this correct motion cannot be guaranteed,the tool calledasoft-tapper is used to keep the tap- perthroughthe spring andthe synchronous errorofrotation andtransferis absorbed. However, since thissoft-tapperisvery expensive, for the decrease of run- ningcost fortapping,high-precision master-slave synchronous positioning control is demanded. In themiddle of the 1980s, not only wasthe present soft-tapper adopted, but alsothe general tapping process wasrealized. At this time, the rotationtimes of master axis is from 3000 to 4000[rpm]. In order to improve productioninthe future,high-speed master axis ro- tationnumberisdemanded.For therelevanthigh-level spring, high-precision master-slave synchronous positioning control is required as well. The relevant 14 1O utline of Mec hatronic Serv oS ystems discussion is carriedout in section7.1. In addition, the possibilityofadapt- ing thismaster-slave synchronous positioningcontrol in contourcontrol is explainedinsection 7.2. 1.2.4 Discussion on the CommandofMechatronic Servo Systems Forimproving the motionperformance of the whole mechatronic servosystem, the methodfor providing the commandtothe servosystem at eachmoment is avery importantfactor.Itmeans that the final desired motionofcurrent mechatr onic servosystems should be approximatedfromthe known informa- tion before the beginning of control. As thepreconditionofuse state of present servosystem, the revision methodfor theknown commandfor realizing the desiredmotion is analyzedinchapter6. (1) Modified TaughtData Method The contour control for athree-dimensional curveinthe presentindustrial robot, the curve is approximated by afolded line. In the contourcontrol, the locus(position) as the form and its motionspeed are the important control parameters. As usual, the ramp input with adesignated slopefor eachaxis as its command is introduced. In suc ha kind of rob ot pe rforming thisc on trol, when giv en three po in ts and angles are described by aline trajectory,atthe corner part, the trajec- tory deviatesf romt he corner po in td ep ending on the ve lo cit y. Certainly ,t he ve lo cit yi sa lso decreased. Fo rd ealing with this kind of situation, skilled op- eratorofteachingissuccessfully carriedout by given taughtdata variedfrom the finaln eeded shap ef or eliminating the deviation fromt he corner po in ti n con tin uous motion. This metho di si llustrated concretely for realizing desired motionbyrevising commandstoservosystem. When approx imating ar ob ot armb ya 1st order delay system and assum- ing it as an orthogonal co ordinate rob ot, concerningt he quite long straight line, the theoretical explanation of this phenomenon realizing skilled operator can be easily carried out. Ho we ve r, it is kno wn thatt his metho di sa lmost im- po ssible by the ab ove form ulation when it is adoptedf or theg eneral mu lti-axis mechatronic servosystem. In sections 6.1,6 .2 and 6.3,t he solutiono ft he metho df or impro ving the effective motionperformance by the taughtpointwhichisacircular trajec- tory butnot lineartrajectory,namely thecomposedtrajectory is given.Here, taking the taughtpointinformation as thedesired final robot motion, the analysis solutionfor theissue, that howthe taught pointinformation is re- visedtobegiven in aservosystem so that the desired motioncan be desired, is illustrated. The flowchartisexpected to rememberthe solutionwhose roots must be definitely usedinamechatronic servosystem. The command methodadoptedinthis book is notonly introducedin this ch apter, but alsoc onsideredf or thep erformance improve men to ft he [...]... controller 2. 1.1 Mechatronic Servo Systems (1) Structure of an Industrial Mechatronic Servo System Fig 2. 1 illustrates the whole structure of a mechatronic servo system As shown in this figure, the industrial mechatronic servo system is the servo system including the mechanism part, the servo motor driving axis included in the mechanism part, the servo motor and the servo controller In this system, the... mechanism part by hardware Reaction force st 1 axis Position control part Velocity control part Position signal Management part Current control part Velocity signal Reference input generator Power control part Current signal Reaction force nth axis Position control part Velocity control part Position signal Current control part Velocity signal Motor Power control part Motor Current signal Fig 2. 1 Industrial... as (2. 8), which retains M Nakamura et al.: Mechatronic Servo System Control, LNCIS 300, pp 17– 52, 20 04 Springer-Verlag Berlin Heidelberg 20 04 18 2 Mathematical Model Construction of a Mechatronic Servo System the necessary parts taking into account the servo properties in the general mechanism by eliminating the unnecessary properties of the servo amplifier converter inverter, etc, from the view of servo. .. PI controller of velocity loop 20 2 Mathematical Model Construction of a Mechatronic Servo System According to these characteristics, the original complex structure of industrial mechatronic servo systems can be simplified using a simple mathematical model in the contour control 2. 1 .2 Mathematical Model Derivation of a Mechatronic Servo System (1) 4th Order Model of an Industrial Mechatronic Servo System. .. the working coordinate and the joint coordinate about articulated robot arm (2) Servo Controller of Industrial Mechatronic Servo System The block diagram of servo system of each axis in a mechatronic servo system is a 13th order or higher high-order system strictly illustrated in Fig 1.1(refer to item 1.1 .2) From Fig 1.1, the information of locus is not feedback in the servo controller From this 13th... management part managing the entire mechanism part and the reference input generator are separated The servo system of each axis is constructed by the motor part , the power amplifier part , the current control part , the velocity control part and the position control part and sensor (position detector, velocity detector, current detector) in order to detect the signal from various parts, and connected...1 .2 Issues in Mechatronic Servo Systems 15 future mechatronic servo system The command method to the servo system, considering the properties of mechanism, the features of disturbance size, the features of process conditions, etc., is regarded as an important item similar with the servo system characteristic improvement as the feedback loop 2 Mathematical Model Construction of a Mechatronic Servo System. .. signal Fig 2. 1 Industrial mechatronic servo system structure Mechanism part 2. 1 4th Order Model of One Axis in a Mechatronic Servo System 19 In an industrial mechatronic servo system, the servo system of each axis is always controlled independently (refer to 1.1 .2 item 6,7) Actually, the interference or friction of each axis is different according to the structure of the mechanism part Although it is possible... action characteristic of mechatronic servo system appropriately In an industrial field, determination of parameters of the servo controller is mostly based on the empirical rule of practician There is no mathematical model comprehensively expressing the mechatronic servo system including all mechanism parts, servo motor, servo controller, etc Since the structure of mechatronic servo systems in industry is... industrial mechatronic servo system introduced in 2. 1.1 (2) , the influence of the axis resonance filter feature and velocity detection filter feature in Fig 1.1 can be neglected due to their slightness When making the current loop transfer function in the servo controller as one and the velocity controller is expressed as P control, the transfer function of the servo controller and the electric part of motor . oneaxis in amechatronic servosystem 3. Performance of multiple axes in amechatronic servosystem 4. Command to servosystem The above viewpoints come from the system components of servosystem in theory.Itmeans. structureofamechatronic servosystem. As shown in this figure, the industrial mechatronic servosystem is the servo system includingthe mechanism part ,the servomotor driving axis included in the mechanismpart,. mechanismmachinesisillustrated. 1 .2. 2Discussion on the Performance of One AxisinaMechatronic ServoSystem In ausual, mechatronic servosystem consists of multi-axis mechanism. When taking into accountthe performance of amechanism machine,