CN101514886B - Method for extracting arc sensor welding gun position deviation information - Google Patents

Abstract

The invention introduces a method for extracting arc sensor welding gun position deviation information. The basic idea of the method is combining a sampling result of a welding current signal with approximation of function to calculate the deviation information of the welding gun position. In the method, the relation of the welding current signal and the welding gun position deviation information under the condition of not considering the interference is derived firstly; then a welding current waveform which is most similar to an actual welding current sampling signal is calculated in minimum mean-square error sense; and the deviation value corresponding with the waveform is the deviation information of the welding gun position to be extracted. The method introduced by the invention can improve the precision of the arc sensor and also considers the integral characteristic of the welding current sampling signal completely to ensure that the deviation extraction result is more reliable.

Description

Method for extracting arc sensor welding gun position deviation information

Technical field:

The present invention is directed to arc welding robot field electric arc sensing technology commonly used, proposed a kind of new deviation information extracting method.Deviation information under this method realizable function space optimal approximation index extracts, and is applicable to swing type arc sensor and rotary electric arc sensor simultaneously.Belong to Automation of Welding, electromechanical integration technology area.

Background technology:

Traditional arc welding robot adopts the mode of " teaching-reproduction " to carry out weld task usually.Yet because the influence of factors such as rigging error, sweating heat distortion makes the teaching track always have certain deviation with actual welds.Therefore for guaranteeing the high-quality weld task of finishing, people have invented various sensing modes and deviation compensation method, and are wherein commonly used with the electric arc sensing mode.

The electric arc sensing has been widely used in the arc welding robot field at present, and the Weld Seam Tracking Control system that depends on the electric arc sensing also is the main flow of present welding automatization technology.The ultimate principle of electric arc sensing is the deviation information when extracting weld joint tracking by observation welding current characteristic, and the electric arc sensing mode that adopts has swing type electric arc sensing, rotary welding torch formula electric arc sensing and mariages electric arc sensing arranged side by side usually.Yet present arc sensor sensing accuracy is not high, dynamic response is also slower, this mainly be because at present usually the extracting method of the electric arc sensing deviation information that adopts such as direct location method, maximum point pairing comparision, about regional integration differential method etc. only considered the part characteristic of welding current, and when analyzing the current waveform characteristics, done linear-apporximation with concerning between deviation information, the inaccuracy that has all caused sensor model is handled in these approximations, makes sensing accuracy be subjected to the restriction of model itself.

At ubiquitous problem in the above-mentioned electric arc Application in Sensing, the present invention proposes a kind of electric arc sensing deviation information extracting method based on continuous function space optimal approximation thought.Its basic thought is the deviation information that the thought of utilizing the sampled result associative function of welding current signal to approach is calculated welding torch position.This method is at first derived the relation of the theoretical waveform of welding current signal with welding gun position deviation information, calculate one then with the theoretical waveform of the most similar welding current of actual welding current sampling signal under the least mean-square error meaning, then the deviate of this waveform correspondence promptly is the deviation information of the welding torch position that will extract.Take into full account the waveform character of welding current observation signal when adopting this method to extract deviation information, avoided approximate to sensor model simultaneously, thereby all obtained bigger improvement aspect the reliability of sensor and the sensing accuracy.

Summary of the invention:

Technical matters: the purpose of this invention is to provide a kind of method for extracting arc sensor welding gun position deviation information, on the basis that arc sensor hardware is formed, provide a kind of more reliably, more accurate deviation information extracting method.

Technical scheme: method for extracting arc sensor welding gun position deviation information, its basic thought is: observable welding current signal is considered as a function Z (t) in the continuous function space, the welding current that theoretical derivation is drawn is { I (the t of family of functions of argument with deviation e with the gang that the funtcional relationship of time t, deviation e is considered as in the continuous function space, e) }, from this family's function, determine optimal approximation unit I (t, an e by the method for solved function extreme value ^*) make its waveform meet the waveform of welding current sampling signal most, then this approaches first pairing deviate e ^*The deviation information that will extract exactly.

The method for extracting arc sensor welding gun position deviation information that the present invention proposes utilizes the sampled result of welding current signal to calculate the deviation information of welding torch position according to the method for approximation of function, concrete steps are that welding current is not being considered that time dependent relation under the disturbed condition is considered as the basis function in continuous function space, and the welding current signal that actual samples is obtained is considered as objective function to be approached; Adopt the similarity of method computing function under the least mean-square error meaning of linear proximity, and find one with the most similar basis function of objective function from these basis functions, then the deviate of this basis function correspondence is exactly the welding gun position deviation that will extract; This method can be applicable to widely used sinusoid swing arc sensor and rotary welding torch formula arc sensor in the Automation of Welding field.

For sine swing formula arc sensor, the welding current time dependent pass under the situation of not considering to disturb that is determined by welding gun position deviation is:

$I(t,e)={\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="H2009100258262E00032.png"\; state="\{\{state\}\}">I</figure-callout>}}_0+K_c|A\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="H2009100258262E00032.png"\; state="\{\{state\}\}">sin</figure-callout>}\frac{2\mathrm{\&pi;Vt}}{L}+e|\tan \mathrm{\&alpha;}$

I in the formula ₀It is welding current sampled value corresponding to the weld seam minimum point; K _CBe a constant, reflected that the torch height variable quantity is with the proportionate relationship between the welding current variable quantity; V represents speed of welding; L represents the distance that the torch swinging one-period advances along bead direction; A represents the amplitude of torch swinging, and e represents that oscillation centre arrives the deviate at weld seam center; α represents the angle of weld edge same level direction; I in the formula ₀, K _CThe current sampling data of the teaching process before can beginning by the electric arc sensing according to the meaning of its expression calculates, and V, L, A are the welding parameters of being set by operating personnel, and α is generally 45 degree;

For rotary welding torch formula arc sensor, the welding current time dependent pass under the situation of not considering to disturb that is determined by welding gun position deviation is:

I(t，e)＝I ₀+K _c|R?sin?ωt+e|tanα

R is the radius that welding gun rotatablely moves in the formula, is the constant by the structures shape of rotary welding gun; ω is the angular velocity that rotatablely moves, and is set by operating personnel, and the definition of other parameter is identical with the situation of sinusoid swing arc sensing.

For sine swing formula arc sensor, the most similar pairing welding gun position deviation value solving equation of basis function of the same objective function that finds under the least mean-square error meaning is:

$e=\frac{\mathrm{sgn}\left(e\right)}{{\mathrm{TK}}_c\tan \mathrm{\&alpha;}}[{\&Integral;}_0^{T}Z\left(t\right)\mathrm{dt}-2{\&Integral;}_{t_{M1}}^{t_{M2}}Z\left(t\right)\mathrm{dt}-I_0(T+2t_{M1}-2t_{M2})]$

T in the formula _M1, t _M2Can represent with deviation e, do e 〉=0 when the oscillation centre of welding gun is positioned at weld seam center left note, at this moment $t_{M1}=\frac{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="H2009100258262E00032.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\mathrm{\&pi;V}}(\mathrm{\&pi;}+\arcsin \frac{e}{A}),$ ${\mathrm{<figure-callout\; id="2"\; label="t\; M"\; filenames="H2009100258262E00032.png"\; state="\{\{state\}\}">t</figure-callout>}}_M=\frac{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="H2009100258262E00032.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\mathrm{\&pi;V}}(2\mathrm{\&pi;}-\arcsin \frac{e}{A});$ When being positioned at right side, weld seam center note, the oscillation centre of welding gun does e＜0, at this moment $t_{M1}=-\frac{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="H2009100258262E00032.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\mathrm{\&pi;V}}\arcsin \frac{e}{A},$ ${\mathrm{<figure-callout\; id="2"\; label="t\; M"\; filenames="H2009100258262E00032.png"\; state="\{\{state\}\}">t</figure-callout>}}_M=\frac{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="H2009100258262E00032.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\mathrm{\&pi;V}}(\mathrm{\&pi;}+\arcsin \frac{e}{A});$ T is the cycle of torch swinging in the formula, can obtain by welding parameter V, the L that sets $T=\frac{L}{V}.$

The present invention can be applicable to all kinds of common arc sensors, comprises sine swing formula arc sensor, triangular wave swing type arc sensor and rotary welding torch formula arc sensor, has broad application prospects.

Beneficial effect: basic thought of the present invention is the deviation information that the thought of utilizing the sampled result associative function of welding current signal to approach is calculated welding torch position, the most similar to sampled signal is not considering that welding current waveform under the disturbed condition determines the deviation information of welding torch position by calculating one.The method that adopts the present invention to propose has taken into full account the global feature of welding current sampling signal, and the result that deviation is extracted is accurate more, reliable.

Concrete advantage of the present invention is:

I. extract reliable results, strong interference immunity.Adopt the method for approximation of function to take into full account the waveform character of welding current sampling signal in whole hunting period, thereby weakened the influence that paroxysmal impulse disturbances and other aperiodicity are disturbed, the antijamming capability as a result that makes deviation extract strengthens, and has higher reliability.

II. improved the precision of electric arc sensing.The present invention unlike other conventional methods as about sensor model is done linearizing approximate processing the regional integration differential method, it is considered as nonlinear function with sensor model and directly calculates, this result who makes deviation extract can approach actual deviation to the full extent, thereby has improved the precision of electric arc sensing.

The present invention is the core of the good arc sensor of design, it also is the basis of realizing electric arc sensing Weld Seam Tracking Control, can be applicable in all kinds of special welding machines or the arc welding robot system, is an important technology realizing Automation of Welding, has broad application prospects.

Description of drawings:

Fig. 1 is for realizing hardware foundation of the present invention, also be the basic composition form of typical electric arc sensing Weld Seam Tracking Control system, mainly comprise: robot controller 1, the source of welding current 2, wire-feed motor 3, welding gun 4, Hall element 5, welded piece 6, analog quantity load module 7, arc welding robot body 8 several sections.

The welding gun forms of motion synoptic diagram of a kind of typical sine swing formula arc sensor that Fig. 2 is suitable for for the present invention.Welded piece 6 has double V-groove straight bead or rectilinear angle welding seam, and just do sinusoidal periodicity crosses motion to welding gun 4 in welded joints.

Fig. 3 is the schematic diagram of the deviation extraction algorithm introduced of the present invention of providing of the sine swing formula arc sensor in 2 in conjunction with the accompanying drawings.Have among Fig. 3: the waveform 9 of the welding current under the different deviates when not considering to disturb, actual welding current signal sample waveform 10, find under the meaning of least mean-square error with the waveform 11 of the most similar welding current of waveform when not considering to disturb of actual welding current sampling signal.Draw the pairing deviate of this waveform at last and be the welding torch position that will extract with the deviation between actual welds.

Fig. 4 is the detailed description of the analog quantity load module 7 in the accompanying drawing 1, the analog signals that comes from Hall element 5 outputs is the normal voltage signal of 0-10V, this signal is sent into analog to digital conversion link 13 behind filtering amplifying element 12, last transformation result is sent into robot controller 1 to be used for the calculating of welding gun position deviation information behind photoelectricity isolation link 14.

Fig. 5 is the program flow diagram of the deviation extracting method of realizing that the present invention introduces, is a part that is embedded in the control program of robot controller 1, mainly finishes the calculating of deviate.

Fig. 6 is the result that one group of method that adopts the present invention to introduce is extracted deviation information, has comprised that the pairing welding current of deviate that the method for actual welding current sampling signal (black line) and employing introduction of the present invention extracts is at the waveform of not considering under the disturbed condition (white line).

Embodiment:

The present invention at first goes out the theoretical expression I of welding current according to the forms of motion of welding gun and torch height with the relation derivation between the welding current, and (t e), and is considered as a function Z (t) in the continuous function space with the sampled signal of welding current.

For the sampled signal Z (t) that utilizes welding current finds the solution the deviate e of welding torch position, at first define one depend on deviation e find the solution index J (e):

J(e)＝‖Z(t)-I(t，e)‖ (1)

Wherein, ‖ ‖ represents to be defined in the norm in the continuous function space, in order to measure two similarity degrees between the function.The target that electric arc sensing deviation information extracts problem is to find the solution a deviate e ^*∈ R makes:

$J\left(e^{*}\right)=\underset{e\&Element;R}{\min }J\left(e\right)---\left(2\right)$

Electric arc sensing deviation information extraction the name of the game is exactly to determine a constant e like this ^*∈ R makes about function of a single variable I (t, the e of t ^*) under the meaning of function space norm, realize optimal approximation to welding current sampling signal Z (t).

Next by selected certain concrete norm form, 2-norm such as the continuous function space, draw and find the solution the concrete funtcional relationship of index J (e) with deviation e, should concern as the formula (6) to embodiment for institute that utilizing function again was that 0 character solves concrete deviate e in the first order derivative of extreme point ^*, this deviate e then ^*The deviation information of the arc sensor that will extract exactly.

The hardware foundation of realization foregoing invention mainly comprises robot controller 1, the source of welding current 2, wire-feed motor 3, welding gun 4, Hall element 5, welded piece 6, analog quantity load module 7, arc welding robot body 8 few component parts as shown in Figure 1.Wherein robot controller 1 is also replaceable is special welding machine controller or other industrial control computer, its mainly act on be the control welding gun motion, calculate the deviation of welding torch position and finish real-time weld joint tracking.The main effect of the source of welding current 2 provides welding institute energy requirement, and wire-feed motor 3 is mainly finished wire feed control, and the source of welding current, wire-feed motor have constituted basic welding system together with welding gun.The effect of Hall element 5 is that bigger actual welding current signal is changed into can be by the normal voltage signal of the 0-10V of computer acquisition.Analog quantity load module 7 is used for gathering the voltage signal of Hall element output.Arc welding robot body 8 drives welding gun as basic topworks and advances and laterally doing periodically to cross and move along weld seam along bead direction.

When the welding beginning, robot controller starts the source of welding current, wire-feed motor begins the welding to welded piece, and gathers the analog voltage signal that welding current obtains by the analog quantity load module after the Hall element conversion.Whenever finish the collection of welding current signal of one-period when controller after, just utilize the welding current signal that collects to calculate the deviation e of current welding torch position according to index J (e) ^*, for J (e) choose with concrete deviation solving equation referring to the introduction in the concrete steps thereafter.So far can finish the electric arc sensing deviation extracting method that proposes among the present invention, utilize the welding gun position deviation information correction robot end's who extracts movement locus to realize real-time weld joint tracking function usually again.

The present invention will be further described below in conjunction with the embodiment of accompanying drawing and sinusoid swing arc sensor.With sinusoid swing arc sensor is example, and the concrete implementation step of this method is as follows, the situation of other electric arc sensing mode such as triangular wave swing type electric arc sensing and rotary welding torch formula electric arc sensing similarly:

Step 1: the derivation welding current is with the funtcional relationship I (e) of welding gun position deviation information.

For situation as shown in Figure 2, when the double V-groove straight bead of welding gun on welded piece was done periodic sine swing, welding current time dependent pass under different deviations was (not considering to disturb):

$I(t,e)={\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="H2009100258262E00032.png"\; state="\{\{state\}\}">I</figure-callout>}}_0+K_c|A\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="H2009100258262E00032.png"\; state="\{\{state\}\}">sin</figure-callout>}\frac{2\mathrm{\&pi;Vt}}{L}+e|\tan \mathrm{\&alpha;}---\left(3\right)$

I in the formula ₀It is welding current sampled value corresponding to the weld seam minimum point; K _CBe a constant, reflected that the torch height variable quantity is with the proportionate relationship between the welding current variable quantity; V represents speed of welding; L represents the distance that the torch swinging one-period advances along bead direction; A represents the amplitude of torch swinging, and e represents that oscillation centre arrives the deviate at weld seam center; α represents the angle of weld edge same level direction.I in the formula ₀, K _CThe current sampling data of the teaching process before can beginning by the electric arc sensing according to the meaning of its expression calculates, V, L, A are the welding parameters of being set by operating personnel, α is generally 45 degree, also promptly for a weld task, only time t and deviation e are unknown arguments in the formula (3).Welding current under the situation of not considering to disturb with the variation relation of deviation and time shown in the accompanying drawing 39.

For rotary welding torch formula arc sensor, welding current time dependent pass under different deviations is (not considering to disturb):

I(t，e)＝I ₀+K _c|R?sin?ωt+e|tanα (4)

R is the radius that welding gun rotatablely moves in the formula, is the constant by the structures shape of rotary welding gun; ω is the angular velocity that rotatablely moves, and is set by operating personnel.The definition of other parameter is identical with the situation of sinusoid swing arc sensing.

For triangular wave swing type arc sensor, welding current time dependent pass under different deviations is (not considering to disturb):

$I(t,e)=\left\{\begin{array}{cc}{\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="H2009100258262E00032.png"\; state="\{\{state\}\}">I</figure-callout>}}_0+K_c|A\frac{\mathrm{Vt}}{L/4}+e|\tan \mathrm{\&alpha;}& t\&Element;[0,\frac{T}{4})\\ {\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="H2009100258262E00032.png"\; state="\{\{state\}\}">I</figure-callout>}}_0+K_c|A\frac{L/2-\mathrm{Vt}}{L/4}+e|\tan \mathrm{\&alpha;}& t\&Element;[\frac{\mathrm{<figure-callout\; id="4"\; label="T"\; filenames="H2009100258262E00012.png"\; state="\{\{state\}\}">T</figure-callout>}}{4},\frac{T}{2})\\ {\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="H2009100258262E00032.png"\; state="\{\{state\}\}">I</figure-callout>}}_0+K_c|A\frac{\mathrm{Vt}-L/2}{L/4}+e|\tan \mathrm{\&alpha;}& t\&Element;[\frac{\mathrm{<figure-callout\; id="2"\; label="T"\; filenames="H2009100258262E00032.png"\; state="\{\{state\}\}">T</figure-callout>}}{2},\frac{3T}{4})\\ {\mathrm{<figure-callout\; id="0"\; label="I"\; filenames="H2009100258262E00032.png"\; state="\{\{state\}\}">I</figure-callout>}}_0+K_c|A\frac{\mathrm{Vt}-L}{L/4}+e|\tan \mathrm{\&alpha;}& t\&Element;[\frac{3\mathrm{<figure-callout\; id="4"\; label="T"\; filenames="H2009100258262E00012.png"\; state="\{\{state\}\}">T</figure-callout>}}{4},T)\end{array}\right.---\left(5\right)$

T is that welding gun is done the triangular wave hunting period in when swing in the formula, can obtain T=L/V by welding parameter V, the L that sets.The definition of other parameter is identical with the situation of sinusoid swing arc sensing.

Step 2: determine the solving equation formula that electric arc sensing deviation information extracts.

Weigh the similarity degree of two functions with least mean-square error as criterion, promptly deviation is extracted index J (e) and is:

$J\left(e\right)={\&Integral;}_0^T{[Z\left(t\right)-I(t,e)]}^2\mathrm{dt}---\left(6\right)$

The solving equation of the deviation e that determines under above-mentioned least mean-square error meaning is:

$e=\frac{\mathrm{sgn}\left(e\right)}{{\mathrm{TK}}_c\tan \mathrm{\&alpha;}}[{\&Integral;}_0^{T}Z\left(t\right)\mathrm{dt}-2{\&Integral;}_{t_{M1}}^{t_{M2}}Z\left(t\right)\mathrm{dt}-I_0(T+2t_{M1}-2t_{M2})]---\left(7\right)$

T in the formula _M1, t _M2Can represent with deviation e, do e 〉=0 when the oscillation centre of welding gun is positioned at weld seam center left note, at this moment $t_{M1}=\frac{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="H2009100258262E00032.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\mathrm{\&pi;V}}(\mathrm{\&pi;}+\arcsin \frac{e}{A}),$ ${\mathrm{<figure-callout\; id="2"\; label="t\; M"\; filenames="H2009100258262E00032.png"\; state="\{\{state\}\}">t</figure-callout>}}_M=\frac{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="H2009100258262E00032.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\mathrm{\&pi;V}}(2\mathrm{\&pi;}-\arcsin \frac{e}{A});$ When being positioned at right side, weld seam center note, the oscillation centre of welding gun does e＜0, at this moment $t_{M1}=-\frac{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="H2009100258262E00032.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\mathrm{\&pi;V}}\arcsin \frac{e}{A},$ ${\mathrm{<figure-callout\; id="2"\; label="t\; M"\; filenames="H2009100258262E00032.png"\; state="\{\{state\}\}">t</figure-callout>}}_M=\frac{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="H2009100258262E00032.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\mathrm{\&pi;V}}(\mathrm{\&pi;}+\arcsin \frac{e}{A}).$ T is the cycle of torch swinging in the formula, can obtain by welding parameter V, the L that sets $T=\frac{L}{V}.$

Deviation solving equation for triangular wave swing type arc sensor and rotary welding torch formula arc sensor needs to derive separately, no longer provides here.

Step 3: the hardware foundation of setting up arc sensor.

According to robot controller, the source of welding current, wire-feed motor, welding gun, Hall element, welded piece, analog quantity load module, the welding robot human body several sections of selecting concrete model shown in the accompanying drawing 1, form the hardware foundation that the present invention realizes.

Step 4: write the program that electric arc sensing deviation information extracts.

Write the control program that electric arc sensing deviation information extracts, the just software section among the present invention according to program flow diagram as shown in Figure 5.This flow process is: when operating personnel finish teaching and start welding robot when beginning weld task, robot controller starts the source of welding current and wire-feed motor in succession, and begins to drive welding gun and advance (as shown in Figure 2) along the weld seam swing.After the swing of welding gun began, robot controller started the analog quantity load module and begins the collection of welding current signal.When robot controller is finished the collection of welding current signal of one-period, with regard to utilizing the welding current signal that collects to bring the deviation information that the deviation solving equation calculates welding torch position into, so far can finish the electric arc sensing deviation information extracting method that proposes among the present invention.Repeat the collection of welding current signal and the sustainable deviate that obtains welding torch position of calculating of deviation information, the correction that is applied to the robot trajectory can be finished real-time weld joint tracking function.

Utilize above several steps can realize the method for extracting arc sensor welding gun position deviation information of introducing among the present invention.

Accompanying drawing 6 has provided the result that actual deviation is extracted test, black lines is actual welding current sample waveform among the figure, and white lines are to adopt the welding current signal of the welding gun position deviation correspondence that the method among the present invention draws at the waveform of not considering under the disturbed condition.Experiment condition is to adopt gas metal-arc welding to meet actual welding speed V=4.5mm/s, welding current 240A (corresponding sampled value I at double V-groove straight bead ₀=1.05V), weldingvoltage 30V.Welding gun is sinusoid swing, wobble length L=2.5mm, amplitude of fluctuation A=2.5mm.With one group of experimental data wherein is example, and when actual deviation was 0.50mm, the deviation that adopts the method among the present invention to extract was 0.41mm, adopt traditional about the deviation that extracts of regional integration differential method be 0.34mm.Comparative result this method has as can be seen obviously improved the precision of arc sensor, and the waveform of the pairing welding current of extraction result when not considering to disturb of also white as can be seen lines representative is also very approaching with the waveform of actual sampled signal from accompanying drawing 6.

Claims (3)

1. method for extracting arc sensor welding gun position deviation information, it is characterized in that: utilize the deviation information of the sampled result of welding current signal according to the method calculating welding torch position of approximation of function, concrete steps are that welding current is not being considered that time dependent relation under the disturbed condition is considered as the basis function in continuous function space, and the welding current signal that actual samples is obtained is considered as objective function to be approached; Adopt the similarity of method computing function under the least mean-square error meaning of linear proximity, and find one with the most similar basis function of objective function from these basis functions, then the deviate of this basis function correspondence is exactly the welding gun position deviation that will extract; This method can be applicable to widely used sinusoid swing arc sensor and rotary welding torch formula arc sensor in the Automation of Welding field.

2. a kind of method for extracting arc sensor welding gun position deviation information according to claim 1, it is characterized in that: for sine swing formula arc sensor, the welding current time dependent pass under the situation of not considering to disturb that is determined by welding gun position deviation is:

$I(t,e)=I_0+K_C|A\sin \frac{2\mathrm{\&pi;Vt}}{L}+e|\tan \mathrm{\&alpha;}$

I in the formula ₀It is welding current sampled value corresponding to the weld seam minimum point; K _CBe a constant, reflected that the torch height variable quantity is with the proportionate relationship between the welding current variable quantity; V represents speed of welding; L represents the distance that the torch swinging one-period advances along bead direction; A represents the amplitude of torch swinging, and e represents that oscillation centre arrives the deviate at weld seam center; α represents the angle of weld edge same level direction; I in the formula ₀, K _CThe current sampling data of the teaching process before can beginning by the electric arc sensing according to the meaning of its expression calculates, and V, L, A are the welding parameters of being set by operating personnel, and α is 45 degree;

For rotary welding torch formula arc sensor, the welding current time dependent pass under the situation of not considering to disturb that is determined by welding gun position deviation is:

I(t，e)＝I ₀+K _c|Rsinωt+e|tanα

R is the radius that welding gun rotatablely moves in the formula, is the constant by the structures shape of rotary welding gun; ω is the angular velocity that rotatablely moves, and is set by operating personnel, and the definition of other parameter is identical with the situation of sinusoid swing arc sensing.

3. a kind of method for extracting arc sensor welding gun position deviation information according to claim 2, it is characterized in that: for sine swing formula arc sensor, the most similar pairing welding gun position deviation value solving equation of basis function of the same objective function that finds under the least mean-square error meaning is:

$e=\frac{\mathrm{sgn}\left(e\right)}{{\mathrm{TK}}_c\tan \mathrm{\&alpha;}}[{\&Integral;}_0^{T}Z\left(t\right)\mathrm{dt}-2{\&Integral;}_{t_{M1}}^{t_{M2}}Z\left(t\right)\mathrm{dt}-I_0(T+2t_{M1}-2t_{M2})]$

T in the formula _M1, t _M2Can represent with deviation e, do e 〉=0 when the oscillation centre of welding gun is positioned at weld seam center left note, at this moment

When being positioned at right side, weld seam center note, the oscillation centre of welding gun does e＜0, at this moment

T is the cycle of torch swinging in the formula, can obtain by welding parameter V, the L that sets

Z (t) is the sampled signal of welding current, K _CBe a constant, I ₀It is welding current sampled value corresponding to the weld seam minimum point.

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