CN103587550A - Device and method for detecting urban rail vehicle wheel diameters through arc vertical installation of sensors - Google Patents

Abstract

The invention discloses a device and method for detecting urban rail vehicle wheel diameters through arc vertical installation of sensors. The device comprises a central processing unit and a plurality of laser sensors connected with the central processing unit. A steel rail at a detection zone deviates outwards, and a protective rail is arranged on the inner side of the steel rail at the detection zone. The laser sensors are arranged between the area vacated by deviation of the steel rail and the protective rail, and probes of the laser sensors are arranged in the direction of the steel rail and evenly distributed on an arc with a fixed chord length radius. Detection light beams of each laser sensor are perpendicular to the steel rail and face upwards, and all the laser sensors are located under wheels and are coplanar with the circumferences of wheels subjected to diameter measurement. According to the method, the laser sensors are used and are installed under the wheels according to the arc vertical relationship, and the wheels are detected to obtain detection points; the initial diameters of the wheels can be obtained through least square fit, and the initial diameters are averaged to obtain the diameters of the wheels. According to the device and method, the advantages of high speed, high accuracy and big diameter measurement scope can be achieved through on-line no-contact type measurement.

Description

Sensor circular arc vertically arranged city rail vehicle wheel diameter detecting device and method

Technical field

The present invention relates to railway wheel detection field, particularly a kind of sensor circular arc vertically arranged city rail vehicle wheel diameter detecting device and method.

Background technology

City rail vehicle there will be abrasion in various degree in the process of operation, and abrasion exert an influence to wheel safe operation meeting, and the wheel diameter that wherein abrasion cause changes particularly key.Train main track is in service, coaxially and with steering framing wheel footpath differ from all limited requirements, the poor excessive wheel that easily causes in coaxial wheels footpath is to scratch, same wheel poor excessive flange wear or the train abnormal vibrations of also easily causing in wheel footpath, therefore to the measurement of wheel diameter to safe train operation important in inhibiting.

Conventional arc radius method of measurement comprises slide calliper rule method and the high chord length method of bow, and wherein slide calliper rule method is applicable to the not high occasion of accuracy requirement, and measurement range is subject to the restriction of arc length, and slide calliper rule range is subject to the restriction of located lateral frame; And the operation of bending high chord length method is more loaded down with trivial details, these two kinds of methods are generally used for workpiece to do static off-line measurement.Chinese patent CN 201159640Y(diameter measurement device of railway wheel, application number: 200820055350.8, the applying date: 2008-02-02) disclose the high chord length method of a kind of bow and measured radius of wheel device, repair method belongs to hand dipping and off-line is measured automatically, needs regularly to send workshop to overhaul after wheel travels a period of time.This static off-line measurement adopts special measuring tool or omnipotent measurer manual detection, the shortcoming such as have that testing result error is large, poor accuracy, rework rate are high, inefficiency, labour intensity are large.

Contactless on-line measurement wheel grows up to geometric parameter gradually to diameter or wheel, Chinese patent CN 1899904A(detector for train wheel pair size online test method and device, application number: 200510035961.7 applyings date: 2005-07-20), the laser displacement sensor of certain distance is installed in the both sides of every one steel rail, sensor is measured obliquely from the bottom side of rail, thereby record wheel tread data, and the speed moving based on train calculating obtains diameter through two laser sensor chord lengths.The shortcoming of the method is, need to utilize train speed information simultaneously, measurement that can not complete independently diameter, and utilize single laser sensor to record tread information, can be because diameter position cannot be accurately located in the variation of tread.The wheel diameter non-contact type dynamic measurement method of Chinese patent CN101219672A(based on laser, application number: 200810056339.8 applyings date: 2008-01-16) adopt two laser displacement sensor direct irradiation wheel tread rolling surfaces, geometry site by sensor installation is measured wheel diameter, the shortcoming of the method does not solve alignment issues for surveying line, and the same approximate method of cutting sth. askew cannot accurately be described wheel diameter.To sum up, still there is the shortcomings such as survey precision is not high, measurement speed of response is slow, engineering construction is difficult in current contactless wheel diameter measurement technique.

Summary of the invention

The object of the present invention is to provide a kind of high-precision sensor circular arc vertically arranged city rail vehicle wheel diameter detecting device and method, adopt non-contact measurement, detection speed is fast, measurement range is large.

The technical solution that realizes the object of the invention is:

The vertically arranged city rail vehicle wheel diameter of a circular arc detecting device, comprises central processing unit and a plurality of laser sensor, and described laser sensor is all connected with central processing unit; The rail of detector segments is outwards offset, and the rail of this detector segments inner side arranges guard rail, tangent inside guard rail and wheel rim; Laser sensor is arranged at rail and is offset between the region and guard rail of vacating, the probe of laser sensor is arranged and is distributed on the fixing circular arc of chord length radius along rail direction, upwards, all laser sensors are coplanar with the wheel circumference that carries out diameter measurement for the vertical rail of detecting light beam of each laser sensor.

The vertically arranged city rail vehicle wheel diameter of a circular arc method of inspection, comprises the following steps:

The 1st step, n laser sensor is installed on to the region that rail skew is vacated, chord length is arranged and be distributed on to the probe of laser sensor along rail direction is that on L, the radius circular arc that is R, upwards, laser sensor is designated as respectively P to the vertical rail of detecting light beam of each laser sensor _i, along rail direction, i is followed successively by 1,2 ... n, the number that n is laser sensor;

The 2nd step, sets up two-dimensional coordinate system in the plane at the wheel circumference that carries out diameter measurement: along rail direction, be X-axis, through first laser sensor P ₁and perpendicular to rail, be upwards Y-axis, each laser sensor probe is with respect to the mounted angle θ of X-axis _ibe 90 °, the coordinate (x of laser sensor _i, y _i) by following formula, determined:

$\left\{\begin{array}{c}{x}_i=\frac{L}{2}-R\&times;\cos {\mathrm{\&beta;}}_i\\ y_i=y_1-R\sin {\mathrm{\&beta;}}_i+\sqrt{R^2-\frac{{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA0000411917790000012.png,HDA0000411917790000023.png"\; state="\{\{state\}\}">L</figure-callout>}}^2}{4}}\end{array}\right.i=\mathrm{1,2}...n$

Wherein, $\begin{array}{cc}{\mathrm{\&beta;}}_i=\frac{\mathrm{\&pi;}}{2}+(i-1-\frac{n-1}{2})\&times;\mathrm{\&beta;}& i=\mathrm{1,2}...n\end{array}$

In formula, β is the definite arc angle of chord length L and radius R,

The 3rd step, gathers the output valve of all laser sensors, and selects and have the valid data of n sensor output value group { S simultaneously _i, S _ibe i sensor P _ioutput valve, i=1,2 ... n;

The 4th step, according to sensor P _ioutput valve S _i, coordinate figure (x _i, y _i), mounted angle θ _idetermine respective sensor P on wheel _imeasurement point coordinate (X _i, Y _i):

(X _i,Y _i)＝(x _i,y _i)+(S _i×cosθ _i,S _i×sinθ _i) i＝1,2…n

The 5th step, according to n on wheel measurement point coordinate (X _i, Y _i) carry out fitting circle, obtain the wheel diameter D of this measuring position;

The 6th step, carries out matching by a plurality of valid data groups that collect and obtains a series of wheel diameters, and a series of wheel diameters that obtain are averaged, and obtains the final wheel diameter D in this measuring position _final.

Compared with prior art, remarkable advantage of the present invention is:, based on laser detection system, by the algorithm of least square fitting, realize the online noncontact measurement of train wheel (1), and survey precision is high; (2) by any multiple spot coordinate of laser sensor automatic acquisition wheel, by corresponding data Processing Algorithm, obtain institute's measuring car wheel diameter instantly, simple, convenient quick; (3) have advantages of that detection speed is fast, measurement range is large.

Accompanying drawing explanation

Fig. 1 is the postrun abrasion schematic diagram of wheel tread.

Fig. 2 is the structural representation of the vertically arranged wheel diameter detecting device of sensor circular arc of the present invention.

Fig. 3 is the schematic diagram of rail switching place in city rail vehicle wheel diameter detecting device of the present invention.

Fig. 4 is the distance Q of rail skew of the present invention and the size generalized section of guard rail.

Fig. 5 is that in embodiment 1, the vertically arranged wheel diameter of laser sensor circular arc detects schematic diagram.

Fig. 6 is the observed reading relation of t (ms) in time of each laser sensor in embodiment 1.

Fig. 7 is a certain moment detection sequence point (X in embodiment 1 _i, Y _i) and matching after circle.

Fig. 8 is the resulting whole diameters of all effective measured data values matchings in embodiment 1.

Fig. 9 is 20 diameter acquired results schematic diagrams of duplicate measurements in embodiment 1.

The specific embodiment

Below in conjunction with drawings and the specific embodiments, the present invention is described in further detail.

Tread profile when having expressed certain wheel operation tread profile later in Fig. 1 and just having put into operation, can find out apart from the 70mm of place, wheel rim side and concentrate and locate for abrasion, this place is conventional measurement diameter position in engineering, and wheel diameter is often controlled between 770～840mm, therefore laser sensor sensing point is chosen for the wheel circumference at this place.

The vertically arranged city rail vehicle wheel diameter of sensor circular arc of the present invention detecting device, comprises central processing unit and a plurality of laser sensor, and described laser sensor is all connected with central processing unit; The rail of detector segments is outwards offset, and the rail of this detector segments inner side arranges guard rail, tangent inside guard rail and wheel rim; Laser sensor is arranged at rail and is offset between the region and guard rail of vacating, the probe of laser sensor is arranged and is distributed on the fixing circular arc of chord length radius along rail direction, upwards, all laser sensors are coplanar with the wheel circumference that carries out diameter measurement for the vertical rail of detecting light beam of each laser sensor.

As shown in Figure 2, in detector segments, rail 6 is outer partially, vacate certain area, laser sensor probe 3 is arranged on to the measurement point below of wheel 1, in wheel rim inner side, guard rail 5 is set and causes derailing to prevent taking turns in S or end float misalignment, laser sensor probe 3 is fixing by clamp of sensor 4, and can adjust position and the inclination angle of laser sensor probe 3, and each laser sensor probe 3 laser beams that send 2 can detect the corresponding check point on wheel simultaneously.

As shown in Figure 3, rail outwards switching place of skew is arc, is conducive to train and enters and exit detecting area.Fig. 4 has illustrated the outwards concrete size Q of skew of rail, and for wheel tread and 60 rails, Q is controlled between 50～65mm, makes track centerline not exceed the outer rim of wheel.Guard rail exceeds the size P of wheel rim, is controlled between 30～50mm.The wheel circumference that carries out diameter measurement is 70mm apart from the distance of wheel rim side.

Due to wheel to be measured and track Long Term Contact, smooth surface roughness is low, therefore relates to and utilizes laser scanning testing head to carry out profile measurement to the very strong metal curved surface of mirror-reflection, and this measurand is a difficult point in current topography measurement field.Zhang Liang etc. have analyzed the measurement capability of existing several laser feeler to metal surface, shown that the holographic probe of cone light polarization and oblique fire formula triangle probe are applicable to measuring metal curved surface (Zhang Liang, Fei Zhigen, Guo Junjie. laser scanning testing head is measured research to metal curved surface, lathe and hydraulic pressure, the 39th the 9th phase of volume: in May, 2011).Therefore the laser sensor the present invention relates to, preferably bores the holographic probe of light polarization and oblique fire formula triangle probe, the quantity of laser sensor be 3～10 and the probe of all laser sensors by clamp of sensor, be fixed on wheel below.

The method of using the vertically arranged city rail vehicle wheel diameter of the sensor circular arc detecting device to carry out wheel diameter detection, comprises the following steps:

The 1st step, n laser sensor is installed on to the region that rail skew is vacated, chord length is arranged and be distributed on to the probe of laser sensor along rail direction is that on L, the radius circular arc that is R, upwards, laser sensor is designated as respectively P to the vertical rail of detecting light beam of each laser sensor _i, along rail direction, i is followed successively by 1,2 ... n, the number that n is laser sensor;

The 2nd step, sets up two-dimensional coordinate system in the plane at the wheel circumference that carries out diameter measurement: along rail direction, be X-axis, through first laser sensor P ₁and perpendicular to rail, be upwards Y-axis, each laser sensor probe is with respect to the mounted angle θ of X-axis _ibe 90 °, the coordinate (x of laser sensor _i, y _i) by following formula, determined:

$\left\{\begin{array}{c}{x}_i=\frac{L}{2}-R\&times;\cos {\mathrm{\&beta;}}_i\\ y_i=y_1-R\sin {\mathrm{\&beta;}}_i+\sqrt{R^2-\frac{{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA0000411917790000012.png,HDA0000411917790000023.png"\; state="\{\{state\}\}">L</figure-callout>}}^2}{4}}\end{array}\right.i=\mathrm{1,2}...n$

Wherein, $\begin{array}{cc}{\mathrm{\&beta;}}_i=\frac{\mathrm{\&pi;}}{2}+(i-1-\frac{n-1}{2})\&times;\mathrm{\&beta;}& i=\mathrm{1,2}...n\end{array}$

In formula, β is the definite arc angle of chord length L and radius R,

The 3rd step, gathers the output valve of all laser sensors, and selects and have the valid data of n sensor output value group { S simultaneously _i, S _ibe i sensor P _ioutput valve, i=1,2 ... n;

The 4th step, according to sensor P _ioutput valve S _i, coordinate figure (x _i, y _i), mounted angle θ _idetermine respective sensor P on wheel _imeasurement point coordinate (X _i, Y _i):

(X _i,Y _i)＝(x _i,y _i)+(S _i×cosθ _i,S _i×sinθ _i) i＝1,2…n

The 5th step, according to n on wheel measurement point coordinate (X _i, Y _i) carry out fitting circle, obtain the wheel diameter D of this measuring position; Adopt method of least square to carry out fitting circle, formula is as follows:

$\begin{array}{cc}D=\sqrt{a^2+{\mathrm{<figure-callout\; id="2"\; label="b"\; filenames="HDA0000411917790000012.png,HDA0000411917790000023.png"\; state="\{\{state\}\}">b</figure-callout>}}^2+4\frac{\mathrm{\&Sigma;}(X_i^2+Y_i^2)+\mathrm{a\&Sigma;}{X}_i+\mathrm{b\&Sigma;}{Y}_i}{n}},& i=\mathrm{1,2}...n\end{array}$

Wherein, a is the center of circle abscissa x after matching ₀-2 times be a=-2x ₀, b is the center of circle ordinate y after matching ₀-2 times be b=-2y ₀, and

$a=\frac{\mathrm{HD}-\mathrm{EG}}{\mathrm{CG}-{\mathrm{<figure-callout\; id="2"\; label="D"\; filenames="HDA0000411917790000012.png,HDA0000411917790000023.png"\; state="\{\{state\}\}">D</figure-callout>}}^2}$

$b=\frac{\mathrm{HC}-\mathrm{ED}}{D^2-\mathrm{GC}}$

Wherein C, D, E, G, H are intermediate parameters, as follows respectively:

$\left.\begin{array}{c}C=\mathrm{n\&Sigma;}{X}_i^2-\mathrm{\&Sigma;}{X}_i\mathrm{\&Sigma;}{X}_i\\ D=\mathrm{n\&Sigma;}{X}_i{Y}_i-\mathrm{\&Sigma;}{X}_i\mathrm{\&Sigma;}{Y}_i\\ E=\mathrm{n\&Sigma;}{X}_i^3+\mathrm{n\&Sigma;}{X}_i{Y}_i^2-\mathrm{\&Sigma;}(X_i^2+Y_i^2)\mathrm{\&Sigma;}{X}_i\\ G=\mathrm{n\&Sigma;}{Y}_i^2-\mathrm{\&Sigma;}{Y}_i\mathrm{\&Sigma;}{Y}_i\\ H=\mathrm{n\&Sigma;}{X}_i^2{Y}_i+\mathrm{n\&Sigma;}{Y}_i^3-\mathrm{\&Sigma;}(X_i^2+Y_i^2)\mathrm{\&Sigma;}{Y}_i\end{array}\right\}i=\mathrm{1,2}...n$

The 6th step, carries out matching by a plurality of valid data groups that collect and obtains a series of wheel diameters, and a series of wheel diameters that obtain are averaged, and obtains the final wheel diameter D in this measuring position _final.

Below in conjunction with specific embodiment, the present invention is described in further detail.

Embodiment 1

The present embodiment is sensor circular arc vertically arranged city rail vehicle wheel diameter detecting device and method.

As shown in Figure 5, along rail direction, to arrange and be distributed on chord length be that on L, the radius circular arc that is R, the vertical rail of detecting light beam of each laser sensor upwards to the probe of n laser sensor.

The external factor that affects laser triangulation sensor accuracy mainly comprises measured surface inclination, surface gloss, roughness, color and scanning speed etc.Sensor adopts circular arc normal form to install, and makes laser sensor probe can aim at tested surface simultaneously, has effectively suppressed the error that tested surface tilts to bring; Be conducive to the preferred process of installation parameter to be analyzed simultaneously, reduced analysis difficulty.

The installation parameter of laser sensor meets the following conditions: the number of laser sensor is n and 3≤n≤10, it is L and n * 30mm≤L≤1800mm that laser sensor is installed chord length, and the vertical distance along the attachment point of first laser sensor of rail direction to track is | y ₁| and | y ₁|>=100mm, laser sensor install arc radius be R and $\sqrt{{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HDA0000411917790000012.png,HDA0000411917790000023.png"\; state="\{\{state\}\}">L</figure-callout>}}^2+{\left|{\mathrm{<figure-callout\; id="1"\; label="y"\; filenames="HDA0000411917790000012.png"\; state="\{\{state\}\}">y</figure-callout>}}_1\right|}^2}\&le;R\&le;5000\mathrm{mm}.$

According to engineering reality and the analysis to measured error, 4 parameters are preferably as follows:

$\left\{\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="y"\; filenames="HDA0000411917790000012.png"\; state="\{\{state\}\}">y</figure-callout>}}_1=-100\\ n=6\\ L=600\\ R=3000\end{array}\right.$

Thereby obtain the coordinate (x of each sensor _i, y _i) (unit: mm):

$\left\{\begin{array}{c}{x}_i=\left[\begin{array}{cccccc}0& 119.93& 239.97& 360.03& 480.07& 600\end{array}\right]\\ y_i=\left[\begin{array}{cccccc}-100& -105.76& -108.65& -108.65& -105.76& -100\end{array}\right]\end{array}\right.$

If the sampling period of laser sensor is 1kHz, measure random error 0.1mm, the tested vechicle wheel measurement data that are 800 by computer modeling generation diameter as shown in Figure 6, are exported diameter by take off data according to following steps:

(1.1) collect all laser sensor output point sequence S _i, and the data when selecting 6 sensors and effectively surveying.Certain constantly wheel through out-of-date effective value:

S _i＝[234.0412 151.6957 118.6378 118.5963 153.0630 236.7570]

(1.2) for the output valve S of sensor _iand attachment point coordinate (x _i, y _i), inclination angle [theta] _i, push away to obtain the point coordinate (X on camber line _i, Y _i); Fig. 7 has drawn S in (1.1) _idefinite sequence of points (X _i, Y _i) and this constantly matching after circle:

$\left\{\begin{array}{c}{X}_i=\left[\begin{array}{cccccc}0& 119.8072& 239.9036& 360.0964& 480.1928& 600.0000\end{array}\right]\\ Y_i=\left[\begin{array}{cccccc}134.2381& 42.2560& 4.2916& 4.7120& 43.1836& 136.5666\end{array}\right]\end{array}\right.$

(1.3) by sequence of points (X _i, Y _i) according to least square fitting circle, to obtain the wheel diameter in this moment be 798.782mm.Fig. 8 is all effective corresponding wheel diameter values of measuring in the moment, and it is that D is 798.5mm～801.5mm that the data in interior all moment of useful range calculate diameter.

(1.4) data in Fig. 8 are averaged, obtain the output diameter D of one-shot measurement _final=799.89mm.And analogue measurement 20 times, obtain the result of a measurement shown in Fig. 9, from this result of a measurement, this embodiment can be realized the high-acruracy survey of wheel diameter, and measured error is not considered <0.25mm in the situation of installation error.

In sum, sensor circular arc vertically arranged city rail vehicle wheel diameter detecting device of the present invention and method, by the algorithm of least square fitting, realize the online noncontact measurement of train wheel, and survey precision is high; By any multiple spot coordinate of laser sensor automatic acquisition wheel, by corresponding data Processing Algorithm, obtain institute's measuring car wheel diameter instantly, simple, convenient quick; And have advantages of that detection speed is fast, measurement range is large.

Claims (7)

1. the vertically arranged city rail vehicle wheel diameter of a sensor circular arc detecting device, is characterized in that, comprises central processing unit and a plurality of laser sensor, and described laser sensor is all connected with central processing unit; The rail of detector segments is outwards offset, and the rail of this detector segments inner side arranges guard rail, tangent inside guard rail and wheel rim; Laser sensor is arranged at rail and is offset between the region and guard rail of vacating, the probe of laser sensor is arranged and is distributed on the fixing circular arc of chord length radius along rail direction, upwards, all laser sensors are coplanar with the wheel circumference that carries out diameter measurement for the vertical rail of detecting light beam of each laser sensor.

2. the vertically arranged city rail vehicle wheel diameter of sensor circular arc according to claim 1 detecting device, is characterized in that, described detector segments rail is skew 50～65mm outwards, and switching place that this rail is outwards offset is arc.

3. the vertically arranged city rail vehicle wheel diameter of sensor circular arc according to claim 1 detecting device, is characterized in that, described in carry out diameter measurement wheel circumference apart from the distance of wheel rim side, be 70mm.

4. the vertically arranged city rail vehicle wheel diameter of sensor circular arc according to claim 1 detecting device, it is characterized in that, the quantity of described laser sensor is for being n and 3≤n≤10, it is L and n * 30mm≤L≤1800mm that laser sensor is installed chord length, and the vertical distance along the attachment point of first laser sensor of rail direction to track is | y ₁| and | y ₁|>=100mm, laser sensor install arc radius be R and

5. the vertically arranged city rail vehicle wheel diameter of sensor circular arc according to claim 1 detecting device, it is characterized in that, the probe of described laser sensor is the holographic probe of cone light polarization or oblique fire formula triangle probe, and the probe of all laser sensors is fixed on wheel below by clamp of sensor.

6. the vertically arranged city rail vehicle wheel diameter of a sensor circular arc method of inspection, is characterized in that, comprises the following steps:

The 1st step, n laser sensor is installed on to the region that rail skew is vacated, chord length is arranged and be distributed on to the probe of laser sensor along rail direction is that on L, the radius circular arc that is R, upwards, laser sensor is designated as respectively P to the vertical rail of detecting light beam of each laser sensor _i, along rail direction, i is followed successively by 1,2 ... n, the number that n is laser sensor;

The 2nd step, sets up two-dimensional coordinate system in the plane at the wheel circumference that carries out diameter measurement: along rail direction, be X-axis, through first laser sensor P ₁and perpendicular to rail, be upwards Y-axis, each laser sensor probe is with respect to the mounted angle θ of X-axis _ibe 90 °, the coordinate (x of laser sensor _i, y _i) by following formula, determined:

$\left\{\begin{array}{c}{x}_i=\frac{L}{2}-R\&times;\cos {\mathrm{\&beta;}}_i\\ y_i=y_1-R\sin {\mathrm{\&beta;}}_i+\sqrt{R^2-\frac{L^2}{4}}\end{array}\right.i=\mathrm{1,2}\&hellip;n$

Wherein, $\begin{array}{cc}{\mathrm{\&beta;}}_i=\frac{\mathrm{\&pi;}}{2}+(i-1-\frac{n-1}{2})\&times;\mathrm{\&beta;}& i=\mathrm{1,2}...n\end{array}$

In formula, β is the definite arc angle of chord length L and radius R,

The 3rd step, gathers the output valve of all laser sensors, and selects and have the valid data of n sensor output value group { S simultaneously _i, S _ibe i sensor P _ioutput valve, i=1,2 ... n;

The 4th step, according to sensor P _ioutput valve S _i, coordinate figure (x _i, y _i), mounted angle θ _idetermine respective sensor P on wheel _imeasurement point coordinate (X _i, Y _i):

(X _i,Y _i)＝(x _i,y _i)+(S _i×cosθ _i,S _i×sinθ _i) i＝1,2…n

The 5th step, according to n on wheel measurement point coordinate (X _i, Y _i) carry out fitting circle, obtain the wheel diameter D of this measuring position;

The 6th step, carries out matching by a plurality of valid data groups that collect and obtains a series of wheel diameters, and a series of wheel diameters that obtain are averaged, and obtains the final wheel diameter D in this measuring position _final.

7. the vertically arranged city rail vehicle wheel diameter of sensor circular arc according to claim 6 method of inspection, is characterized in that, described in the 5th step according to n on wheel measurement point coordinate (X _i, Y _i) carry out fitting circle, adopt method of least square, formula is as follows:

$\begin{array}{cc}D=\sqrt{a^2+b^2+4\frac{\mathrm{\&Sigma;}(X_i^2+Y_i^2)+\mathrm{a\&Sigma;}{X}_i+\mathrm{b\&Sigma;}{Y}_i}{n}},& i=\mathrm{1,2}...n\end{array}$

Wherein, a is the center of circle abscissa x after matching ₀-2 times be a=-2x ₀, b is the center of circle ordinate y after matching ₀-2 times be b=-2y ₀, and

$a=\frac{\mathrm{HD}-\mathrm{EG}}{\mathrm{CG}-D^2}$

$b=\frac{\mathrm{HC}-\mathrm{ED}}{D^2-\mathrm{GC}}$

Wherein C, D, E, G, H are intermediate parameters, as follows respectively:

$\left.\begin{array}{c}C=\mathrm{n\&Sigma;}{X}_i^2-\mathrm{\&Sigma;}{X}_i\mathrm{\&Sigma;}{X}_i\\ D=\mathrm{n\&Sigma;}{X}_i{Y}_i-\mathrm{\&Sigma;}{X}_i\mathrm{\&Sigma;}{Y}_i\\ E=\mathrm{n\&Sigma;}{X}_i^3+\mathrm{n\&Sigma;}{X}_i{Y}_i^2-\mathrm{\&Sigma;}(X_i^2+Y_i^2)\mathrm{\&Sigma;}{X}_i\\ G=\mathrm{n\&Sigma;}{Y}_i^2-\mathrm{\&Sigma;}{Y}_i\mathrm{\&Sigma;}{Y}_i\\ H=\mathrm{n\&Sigma;}{X}_i^2{Y}_i+\mathrm{n\&Sigma;}{Y}_i^3-\mathrm{\&Sigma;}(X_i^2+Y_i^2)\mathrm{\&Sigma;}{Y}_i\end{array}\right\}i=\mathrm{1,2}...n.$

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