Technology of drive of linear feed servo reachs his to control mode

Inductive type communicates type of servo electromotor induction to communicate servo electromotor point-blank point-blank normally by power supply of SPWM frequency conversion, use the vector commutation with sub directional magnetic field to control a technology, to its the parameter such as athletic position, speed, thrust undertakes fast and accurate control. Because inductive formula is straight the primary core length of servo electromotor is finite, fore-and-aft two end leave, in two fore-and-aft brim is formed " the effect that carry a department " (Endeffect) , make mutual inductance unequal between three-phase winding, cause the moving asymmetry of electromotor. The method that eliminates this kind of asymmetry has 3 kinds: Use 3 identical motor at the same time, its winding across establishs ties, can obtain symmetrical three phase current so; To cannot using the occasion of 3 electromotor at the same time, can use increase extremely the method of several will reduce the difference between each photograph; Outside core end ministry installation compensates coil. 2.

Magneto is linear servo electromotor magneto is linear of servo electromotor sub it is to use high-energy permanent magnet, electromotor uses rectangular wave or control of sine wave electric current, by the power supply of voltage source inverter that IGBT comprises, PWM modulation. After connecting electric current of three-phase semmetry sine to the middle of mover winding, linear electromotor generation shows the travelling wave magnetic field that sine distributings along linear direction translation, produce electromagnetism thrust with the interaction of excitation magnetic field of permanent magnet, the opposite way that drives movement of magnetic field of mover follow wave makes linear motion. The speed that the basic structure that its control a system is PID composition, voltaic double closed-loop control, direct and controlled is electric current, the control that uses Id=0 normally is politic, make electromagnetism thrust and Id have linear concern. 2, the advantage with the biggest technology of drive of linear feed servo is linear the advantage with the biggest technology of feed servo drive is to have than rotating electromotor is gotten greatly add more, decelerate is spent (can amount to 10 ～ 30 times) , the high speed status that can achieve instantaneous to achieve set below very high feed rate and instantaneous falls in high speed accurate suspend campaign. Add decelerate process shorten, quality of ameliorable treatment surface, improve cutting tool service life and manufacturing efficiency; Reduced intermediate segment, make transmission stiffness rises, raised transmission precision and dependability effectively, and feed journey accepts restriction scarcely. 3, the applied current situation of drive of linear feed servo regards a kind of brand-new feed drive as the technology, its superior high speed performance and extremely high dynamic performance, make its get quickly between production applied extensively. In last centuries 90 time metaphase: Above all by German Ex, Cell, machining center of horizontal of the XHC240 that O company develops high speed, 3 feed axis all uses inductive type to communicate servo electromotor point-blank first direct drive; The HVM4800 of machining center of high speed horizontal that then company of American Ingersoll milling machine produces and HVM600, axis of X, Y, Z all uses magneto synchronism drive of linear servo electromotor; The grinding machine of high speed tool that company of aircraft of Japanese Mitsui essence produces, the Z axis that moves quickly up and down also is to introduce drive of linear servo electromotor. The high speed machining center that exhibits on the exposition of Parisian international EMO(Electromechanicaloptical) 1999 especially, top speed amounts to 400m/min, make the representative technology of machine tool of new generation numerical control. Company of science and technology of the silver on province of our country Taiwan already also used linear servo motor at 3 coordinate to measure on machine, realize 3 axes direct drive. The manufacturer of famous machine tool that shows alive bound each country (the big world company of the Mazak company that is like Japan and Korea) the numerical control machine tool that rolls out drive of linear servo electric machinery in succession, and DMG company of Germany already sold the numerical control machine tool that uses drive of linear servo electric machinery to make an appointment with 1000 2001, achieved nearly 2000 2002. All sorts of evidence make clear, drive of linear servo electric machinery already was entered in the application on machine tool of high speed expensive precision work quicken growth period. A kind of new-style much working procedure is at present shunt-wound machine tool of orgnaization numerical control namely alleged " 6 legs machine tool " , call again " 6 sufficient bug " , and in developing research at present " 3 legs " fictitious axis machine tool, it is the applied domain with potential system of linear servo drive. 4, the control mode high speed of system of drive of linear feed servo and the servo actuating device that exceed high speed to machine machine tool of demand numerical control are had extremely tall add, decelerate spends function, and raised quite tall requirement likewise to servo precision. High speed and high accuracy are contradictory, often get satisfaction at the same time hard, but must get satisfaction at the same time in system of linear servo drive, this controls a system to must adopt effective control strategy to restrain all sorts of disturbing with respect to the requirement. A successful control strategy always is based on the understanding that is clear about basically to object model structure, from some the character of specific target sets out, be aimed at the different account that generation disturbs, adopt corresponding control technique, realize effective control. Satisfying main requirement while, servo of give attention to two or morethings is mixed to the traceability of the instruction interference rejection ability. The control strategy that uses in system of control of linear feed servo basically includes: 1.

Traditional control pattern is in object model is affirmatory, indeclinable and for linear, below the circumstance with changeless environment of operation condition, motion, using a tradition to control mode is a kind of effective control method. Traditional control pattern includes the PID feedback control, control that solve Ou, Smith beforehand appraise control algorithm. Among them PID control algorithm is the basiccest control form in communicating system of servo electromotor drive, control application is wide. Smith estimates beforehand implement as shunt-wound as controller, the effect of speed feedback lag that measures lag place to cause to solving defer of power transmission of the inverter in servo and speed is very significant, dominate algorithmic union with other, can form more effective control strategy. 2.

The treatment of contemporary control mode in high accuracy small feed domain, when waiting, the change of all sorts of the structure that must consider a target and parameter change, nonlinear influences, moving environment and interference change and inaccuracy decides an element, ability gets satisfactory control result. Accordingly, the control that uses contemporary control technology at linear servo electromotor considered to get the expert's height takes seriously controlling. (1) can be divided from adaptive control cardinal principle from adaptive control mix from adaptive control for model reference from corrective control two sort. The model is referenced from adaptive control it is the basic return circuit that dominates object composition in controller ─ outside, still build to mix the add adjustment that what get used to orgnaization composition oneself by referenced model circuit. The output that gets used to an orgnaization oneself can change the parameter of controller, or additional to controlling an object to arise control function, make the output of the output of servo electromotor and referenced model keeps consistent. Dominate return circuit from corrective pilot, by differentiate implement design orgnaization composition with controller, differentiate implement the input according to the object and output signal, the parameter of online estimation object, the true value that serves as an object with this estimation sends the design of controller the orgnaization, good by the design control law has consideration, computation sends a person as a result adjustable controller, form new control output, in order to compensate the characteristic change of the object. Change of characteristic to linear servo electromotor parameter disturbs one kind slow the influence that reachs other outside to disturb pair of systematic servo function, can use try to reduce from adaptive control strategy or eliminate. (2) slippery model changes the structure controls slippery model to change structural control system is a kind special nonlinear system, its are nonlinear expression is pilot discontinuous, namely one kind makes system " structure " the switch that changes at any time is characteristic. Use discontinuous control law to alternate ceaselessly systematic structure, the condition that forces a system moves on booked dimensional trajectory. Inside the domain that final progress step by step is nodded firmly on the balance or equilibrium point allows, slide mode moves namely. Once enter slippery model state,this the biggest advantage that commands a method is a system, disturb to controlling object parameter to reach change is not sensitive, need not online differentiate with the design, have complete from adaptability and rash club sex, received successful application in linear servo consequently. (The uncertainty that 3) rash club controls model of object of the control in be aimed at servo to exist (include model uncertainty, fall rank of approximate, nonlinear linearization, parameter and character when change, drift, outside disturbs wait for) , the stability that tries to maintain a system rash club sex and character rash club sex. H ∞ control is among them relatively mature method, this method is the transfer function matrix from the system system of design setting out, make system by disturb to model number takes minimum or be less than some set-point to the H ∞ of the transfer function matrix of deviation, design controller accordingly, disturb to restraining have favorable effect. (4) foreknows control foreknows control not only be worth according to current target, and according to prospective end value and prospective interference decide current control plan, make whole of the deviation between target cost and controlled quantity the smallest. This is the frame of best control theory that during belonging to whole process to control, some evaluates function to take the smallest cost. Foreknow control servo is add on the foundation of common servo of use future information before after make a present of is compensated, form, it can reduce a goal greatly value and controlled the phasic defer of the quantity, make foreknow thereby become the control method with truly practical servo. 3.

The servo appropriate with intelligent control mixed to controlling object environment and job pattern uses intelligence to control a method. Nerve network and ambiguous and logistic control, expert control are current more typical intelligence controls strategy. Blur among them controller, already had commercial special chip, precision of good because of sex of its real time, control is tall, already got applied in servo. Nerve network from theoretic tell possess very strong information integrated ability, below the circumstance that in computation speed can assure, can solve aleatoric and complex control problem. But the hardware support that lacks corresponding nerve network computer at present, what the application in linear servo remains to be produced at chip of nerve network integrated circuit is mature; And expert control is used in complex process control commonly, the research in servo is less. 5, machine tool of last word numerical control uses linear servo motor system of direct drive feed, although alternate among leave out link, implementation is alleged 0 drive, construction of system is had more rationality, but the technical difficult problem that still faces a lot of reality as a kind of new application technology. System of such as control disturbs to parameter perturbation, load those who wait for a lot of inaccuracy to decide electromotor of the interference rejection problem of the element, linear servo is compulsive medicinal powder hot issue, system is sucked quickly can problem of apply the brake reachs the strict and dustproof measure that lie between magnetism wait, all these real problems remain to be mixed at be being solved further of the technology perfect further. In addition, although technology of linear servo drive is in the application in numerical control machine tool and development rate are very rapid, but this does not mean it very can fast replace completely rotate the drive means of servo electromotor. In reach a paragraph of quite long henceforth period at present inside, apply or rotate of the mainstream electromotor and the drive kind that photograph of ball guide screw ties. But the mainstream development direction that technology of linear servo drive regards drive of servo of numerical control machine tool as the technology and capacious applied prospect do not hold doubt. CNC Milling