CN105835901A - Method and system for detecting train wheel diameters - Google Patents

Abstract

The invention discloses a method and a system for detecting train wheel diameters. The method comprises the following steps: receiving a group of time sequences generated when train wheels pass by through laser emitting-receiving devices; calculating an instantaneous velocity at which the wheels pass by firstly in conjunction with field mounting parameters; calculating chord lengths of lasers on the wheels through the velocity; lastly, calculating the wheel diameters through a corresponding algorithm. According to the method and the system, only two laser emitting-receiving devices need to be adopted, so that a large amount of cost is saved; the instantaneous velocity of a train can be obtained without any additional train velocity detection device; the two laser emitting-receiving devices can be used for calculating the wheel diameters separately, and results are averaged, so that errors can be reduced greatly.

Description

The method of a kind of train wheel diameter detection and system thereof

Technical field

The invention belongs to rail vehicle on-line monitoring technique field, the side of a kind of train wheel diameter detection Method and system thereof.

Background technology

In urban track traffic, wheel is one of parts of loss maximum in EEF bogie.The state of wheel with The safe operation of train is closely related, as the size of wheel is had strict requirements, use not to conform to by train operation The wheel required can make to jolt in train operation the security incidents such as even derailing.Wherein wheel diameter is as car One of important indicator of wheel state, has a great impact safe train operation.Therefore, the inspection to wheel diameter Survey is the most necessary.

At present, in wheelset profile context of detection, the mode of the most widely used manual measurement at present.Manual measurement is adopted With wheel footpath chi, proficiency and the field condition measured by artificial dynamics, workman during measuring have closely Relation, there is bigger error in manual measurement.On the other hand, owing to train wheel number is more, use artificial Metering system is time-consuming relatively big, and overhaul efficiency is extremely low.

In recent years, along with laser and the development of image technique, occur in that a collection of contactless wheel calipers And method.As Chinese patent CN1899904A (detector for train wheel pair size online test method and device) utilizes four Individual laser displacement sensor based on PSD, obtains the train wheel end face distance to laser detector, then Calculate wheel rim thickness, wheel rim is high, take turns footpath value.Laser sensor needed for this method is expensive, to installation Angle is more strict, is unfavorable for that large-scale promotion uses.

Summary of the invention

It is an object of the invention to provide a kind of structure lay convenient, calculate that speed is fast, measurement result arranges accurately The detection method of car wheel diameter and system thereof.

The technical solution realizing the object of the invention is: a kind of train wheel diameter detection method and be System, comprises the following steps:

Step 1, sensor laying: along train direction of advance, two Laser emission dresses are installed in side in orbit Putting, be designated as S1, S2 respectively, two laser beam emitting devices and are parallel to track extension side on same straight line The vertical direction that the laser launched to, laser beam emitting device extends along track by directive track inside track outside； Installing two laser receivers outside track successively, be designated as R1, R2, two laser receivers are in On same vertical plane and this vertical plane is parallel to track bearing of trend, R1 receives the laser that S1 sends, and R2 connects Receive the laser that S2 sends；The laser of S1, S2 transmitting and the horizontal wire clamp being perpendicular to face, track bearing of trend place Angle is respectively α₁、α₂, laser beam emitting device S1, S2 are in the spacing between same level height and laser beam Height for L, laser beam emitting device S1, S2 place is less than orbit plane to ensure laser transmitting set and row The safety of car；

Step 2, the acquisition of installation parameter: place a wheel for demarcation in orbit right, it is thus achieved that S1 launches The hot spot that stays on wheel medial surface of laser be H to track upper surface horizontal plane height₁, S2 launches The hot spot that stays on wheel medial surface of laser be H to track upper surface horizontal plane height₂；

Step 3, sensing data obtains: when wheel is through out-of-date, and laser receiver R1, R2 can warps respectively Going through the state of " ON-OFF conducting ", laser receiver records the moment of each state change, often One wheel can obtain the one group of time series being made up of four time data；

Step 4, car speed obtains: when the train position that laser sensor is installed in step 1, root According to time data when spacing L of laser beam emitting device S1, S2 and state change, obtain wheel by setting Instantaneous velocity time standby；

Step 5, wheel diameter obtains: the train instantaneous velocity obtained according to step 4, when passing through in conjunction with wheel Moment, obtain the chord length that laser is beaten on wheel, thus be calculated wheel diameter.

The present invention compared with prior art, its remarkable advantage: (1) only need to use two Laser emission to receive devices, The most cost-effective；(2) need not extra vehicle speed detector device and i.e. can get the instantaneous velocity of train；(3) Two Laser emission receive device and independently calculate wheel diameter, and are averaging result, can reduce greatly Error；(4) there is the advantages such as on line non contact measurement, provide one for realizing wheel diameter on-line measurement The higher solution of degree of accuracy.

Below in conjunction with the accompanying drawings the present invention is described in further detail.

Accompanying drawing explanation

Fig. 1 is the flow chart of wheel diameter detection method of the present invention.

Fig. 2 is the sensor scheme of installation of wheel diameter of the present invention detection.

Fig. 3 is the sensor artwork of wheel diameter of the present invention detection.

Fig. 4 is that sectional view installed by the sensor of wheel diameter of the present invention detection.

Fig. 5 is wheel moment sequence diagram of the present invention.

Fig. 6 is diameter Computing Principle explanatory diagram.

Detailed description of the invention

In conjunction with Fig. 1, the method for train wheel diameter of the present invention detection, comprise the following steps:

Step 1, sensor laying: as in figure 2 it is shown, along train direction of advance, side installs two in orbit Individual laser beam emitting device, is designated as S1, S2 respectively, and two laser beam emitting devices are on same straight line and parallel In track bearing of trend, the vertical direction that the laser that laser beam emitting device is launched extends along track is penetrated by inside track Outside track；Two laser receivers are installed outside track successively, are designated as R1, R2, two laser Reception device is in the same vertical plane and this vertical plane is parallel to track bearing of trend, and R1 receives what S1 sent Laser, R2 receives the laser that S2 sends；S1, S2 launch laser be perpendicular to track bearing of trend place The horizontal line angle in face is respectively α₁、α₂, as it is shown on figure 3, laser beam emitting device S1, S2 are in same water Spacing between flat height and laser beam is L, and the height at laser beam emitting device S1, S2 place is put down less than track Face is to ensure laser transmitting set and the safety of train.

Described laser beam emitting device is made up of modulating-coding and generating laser, and laser receiver is by laser pick-off Device, amplification detector and modem composition, modulating coder modulates the laser of certain frequency and is sent out by laser Emitter sends；When laser pickoff receives laser, by laser demodulator, the frequency of laser can be solved Analysis, records the moment starting to irradiate and terminate to irradiate, if laser frequency is not inconsistent splice grafting when laser frequency meets Receipt part, illustrates that this light is noise or interference, is filtered.Above-mentioned laser " receives and judges note Record " the process used time within 30 microseconds with ensure diameter measurement precision.

Described distance L between laser beam emitting device S1, S2 should meet: 840mm < L < 3140mm, i.e. L should be greater than the diameter value (840mm) of standard wheels pair, and the laser preventing S1 Yu S2 transmitting is beaten simultaneously Situation on wheel, causes the interference between laser and seasonal effect in time series chaotic, and L should be less than bogie The diameter value (840mm) of wheel base (2300mm) and standard wheels pair and value, make a wheel measure Period does not have another wheel and enters the detection region of S1.

Step 2, the acquisition of installation parameter: as shown in Figure 4, place a wheel for demarcation in orbit right, The hot spot that the laser that acquisition S1 launches stays on wheel medial surface to track upper surface horizontal plane height is H₁, the hot spot that the laser of S2 transmitting stays on wheel medial surface to track upper surface horizontal plane height is H₂.Laser beam and horizontal sextant angle α₁、α₂Should meet: the laser that S1, S2 launch is radiated at inside wheel, light Speckle height is less than the wheel center of circle, the brake block that higher than rail level and will not be irradiated to wheel and other underbody devices On.Wheel medial surface is: parallel with the plummet face at the centrage place of track, translates 70mm inside track Face, place.

Step 3, sensing data obtains: as it is shown in figure 5, when wheel is through out-of-date, laser receiver R1, R2 can experience the state of " ON-OFF conducting " respectively, and laser receiver is recorded each state and become In the moment changed, each wheel can obtain the one group of time series being made up of four time data.Time series has The following four moment is constituted successively: 1. R1 is by the moment t of " ON-OFF "₁；2. R1 is by " cut-off Conducting " moment t₂；3. R2 is by the moment t of " ON-OFF "₃；4. R2 by " cut-off conducting " time Carve t₄。

Step 4, car speed obtains: when the train position that laser sensor is installed in step 1, root According to time data when spacing L of laser beam emitting device S1, S2 and state change, obtain wheel by setting Instantaneous velocity time standby.Wherein wheel by time instantaneous velocity calculated by the following step:

1st step, obtains distance L between laser beam emitting device S1, S2 according to step 1；

2nd step, obtains wheel according to step 3 and starts to block the moment t of S1₁With start to block the moment t of S2₃, And spacing L of S1, S2 laser beam tries to achieve an Instantaneous velocity values V₁；The moment of S1 is left according to wheel t₂With the moment t leaving S2₄, and spacing L of S1, S2 laser beam tries to achieve an Instantaneous velocity values V₂, its In:

$V_1=\frac{L}{t_3-t_1}$

$V_2=\frac{L}{t_4-t_2}$

3rd step, to speed V₁、V₂This wheel of acquisition of averaging blocks S1 to finally walking out S2 range from starting The average speed of period

$\stackrel{\&OverBar;}{v}=\frac{V_1+V_2}{2}=\frac{1}{2}(\frac{L}{t_3-t_1}+\frac{L}{t_4-t_2}).$

Step 5, wheel diameter obtains: the train instantaneous velocity obtained according to step 4, when passing through in conjunction with wheel Moment, obtain the chord length that laser is beaten on wheel, thus be calculated wheel diameter.Obtaining of this wheel diameter Access method is as follows:

1st step, according to step 4 obtain wheel by time average speed

2nd step, obtains wheel according to step 3 and starts to block the moment t of S1₁With the moment t leaving S1₂, try to achieve Chord length l that S1 streaks on wheel₁；Obtain wheel according to step 3 and start to block the moment t of S2₃With from Open the moment t of S2₄, try to achieve chord length l that S2 streaks on wheel₂, wherein:

$l_1=(t_2-t_1)\&CenterDot;\stackrel{\&OverBar;}{v}$

$l_2=(t_4-t_3)\&CenterDot;\stackrel{\&OverBar;}{v}$

3rd step, if wheel rim apex circle radius is R, wheel rim height is known as h, tries to achieve S1 laser at wheel medial surface On streak track distance the wheel center of circle vertical height be R-H₁-h, can be passed through Pythagorean theorem by chord length Try to achieve one radius R of wheel rim apex circle₁, the wheel rim apex circle diameter of twice deducts the wheel rim height h of twice again and tries to achieve Wheel diameter r₁, i.e. pass through Pythagorean theorem

$R^2={(R-H_1-h)}^2+{\left(\frac{l_1}{2}\right)}^2$

The wheel rim apex circle radius value trying to achieve wheel is:

$R_1=\frac{H_1+h}{2}+\frac{l_1^2}{8(H_1+h)}$

The wheel rim apex circle diameter of twice deducts the wheel rim height h of twice again and tries to achieve wheel diameter r₁

$r_1=2R_1-2h=H_1-h+\frac{l_1^2}{4(H_1+h)}$

In like manner, the vertical height in the track distance wheel center of circle that S2 laser streaks on wheel medial surface is R-H₂-h, is tried to achieve wheel rim apex circle another radius R by chord length by Pythagorean theorem₂, the wheel rim summit of twice Circular diameter deducts the wheel rim height h of twice again can be in the hope of wheel diameter r₂, i.e. pass through Pythagorean theorem

$R^2={(R-H_2-h)}^2+{\left(\frac{l_2}{2}\right)}^2$

Another wheel rim apex circle radius trying to achieve wheel is:

$R_2=\frac{H_2+h}{2}+\frac{l_2^2}{8(H_2+h)}$

The wheel rim apex circle diameter of twice deducts the wheel rim height h of twice again and tries to achieve wheel diameter r₂:

$r_2=2R_2-2h=H_2-h+\frac{l_2^2}{4(H_2+h)}$

4th step, owing to twice Error weight is identical, therefore the meansigma methods taking twice measurement is final as wheel diameter Measurement result.Two the wheel diameter values obtained in 3rd step are averaging reduction error, and its meansigma methods is as row Car wheel diameter r:

$r=\frac{r_1+r_2}{2}-h+\frac{l_1^2}{4(H_1+h)}+\frac{l_2^2}{4(H_2+h)}$

In conjunction with Fig. 2, Fig. 3 and Fig. 4, the device of train wheel diameter of the present invention detection, process including with central authorities Two laser beam emitting devices of unit and laser receiver, along train direction of advance, side is installed in orbit Two laser beam emitting devices, are designated as S1, S2 respectively, and two laser beam emitting devices and are put down on same straight line Row in track bearing of trend, the vertical direction that the laser that laser beam emitting device is launched extends along track by track inside Outside directive track；Installing two laser receivers outside track successively, be designated as R1, R2, two are swashed Optical pickup apparatus is in the same vertical plane and this vertical plane is parallel to track bearing of trend, and R1 receives S1 and sends Laser, R2 receives the laser that sends of S2；S1, S2 launch laser be perpendicular to track bearing of trend institute Horizontal line angle in face is respectively α₁、α₂, laser beam emitting device S1, S2 are in same level height and swash Spacing between light beam is L, and the height at laser beam emitting device S1, S2 place is sharp to ensure less than orbit plane Light-emitting device and the safety of train；

Place a wheel for demarcation in orbit right, it is thus achieved that the laser that S1 launches stays on wheel medial surface Under hot spot be H to track upper surface horizontal plane height₁, the laser that S2 launches stays on wheel medial surface Under hot spot be H to track upper surface horizontal plane height₂；

When wheel is through out-of-date, laser receiver R1, R2 can experience " ON-OFF conducting " respectively State, laser receiver record each state change moment, each wheel can obtain by four moment One group of time series of data composition；

Described CPU includes car speed acquisition module and wheel diameter acquisition module, at car speed In acquisition module, when the position that train is installed through laser sensor, according to laser beam emitting device S1, S2 Spacing L and state change time time data, obtain wheel by equipment time instantaneous velocity；At car In wheel diameter acquisition module, according to train instantaneous velocity, in conjunction with wheel by time moment, obtain laser and beat Chord length on wheel, thus it is calculated wheel diameter.

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

Embodiment

In conjunction with Fig. 3 and Fig. 4, side installs four laser beam emitting devices successively in orbit, launcher position away from For 0.45m inside leaving the right or normal track, angle [alpha] is 36 °, between the laser beam of actual measurement laser beam emitting device S1, S2 Distance L₁For 1.202m.The hot spot of S1 is at the height H of medial surface₁The hot spot of=215mm, S2 is at medial surface Height H₂=213mm, the wheel rim of wheel is a height of it is known that h=29.3mm.

Method according to step 3, it is stipulated that speed is that 5km/h passes through equipment, can obtain train by equipment Time series.Take one of them sequence to carry out calculating demonstration: t₁=1.076s；t₂=1.644s；t₃=1.942s； t₄=2.508s.

According to method in step 4, in conjunction with the numerical value of L, the instantaneous velocity being calculated train is:

$\stackrel{\&OverBar;}{v}=1.3896m/s$

According to method in step 5 into, the speed of the train recorded in step 3 is brought radius calculation formula, permissible Recording a diameter of 881.1878mm of wheel rim apex circle of this wheel, wheel diameter is 822.5878mm.This The manual measurement value of the wheel diameter calculated is 822.6mm, it is seen that it is straight that the method can measure wheel the most accurately Footpath.

Claims (9)

1. the method for a train wheel diameter detection, it is characterised in that comprise the following steps:

Step 1, sensor laying: along train direction of advance, two Laser emission dresses are installed in side in orbit Putting, be designated as S1, S2 respectively, two laser beam emitting devices and are parallel to track extension side on same straight line The vertical direction that the laser launched to, laser beam emitting device extends along track by directive track inside track outside； Installing two laser receivers outside track successively, be designated as R1, R2, two laser receivers are in On same vertical plane and this vertical plane is parallel to track bearing of trend, R1 receives the laser that S1 sends, and R2 connects Receive the laser that S2 sends；The laser of S1, S2 transmitting and the horizontal wire clamp being perpendicular to face, track bearing of trend place Angle is respectively α₁、α₂, laser beam emitting device S1, S2 are in the spacing between same level height and laser beam Height for L, laser beam emitting device S1, S2 place is less than orbit plane to ensure laser transmitting set and row The safety of car；

Step 2, the acquisition of installation parameter: place a wheel for demarcation in orbit right, it is thus achieved that S1 launches The hot spot that stays on wheel medial surface of laser be H to track upper surface horizontal plane height₁, S2 launches The hot spot that stays on wheel medial surface of laser be H to track upper surface horizontal plane height₂；

Step 3, sensing data obtains: when wheel is through out-of-date, and laser receiver R1, R2 can warps respectively Going through the state of " ON-OFF conducting ", laser receiver records the moment of each state change, often One wheel can obtain the one group of time series being made up of four time data；

Step 4, car speed obtains: when the train position that laser sensor is installed in step 1, root According to time data when spacing L of laser beam emitting device S1, S2 and state change, obtain wheel by setting Instantaneous velocity time standby；

Step 5, wheel diameter obtains: the train instantaneous velocity obtained according to step 4, when passing through in conjunction with wheel Moment, obtain the chord length that laser is beaten on wheel, thus be calculated wheel diameter.

Method the most according to claim 1, it is characterised in that in step 1, laser beam emitting device is by modulating Coding and generating laser form, and laser receiver is by laser pickoff, amplification detector and modem Composition, modulating coder modulates the laser of certain frequency and is sent by generating laser；When laser pickoff receives During to laser, by laser demodulator, the frequency of laser can be resolved, record when laser frequency meets Start irradiate and terminate irradiate moment, if laser frequency does not meets condition of acceptance, illustrate this light be noise or Interference, is filtered.Above-mentioned laser " receive judge record " the process used time within 30 microseconds with Ensure the precision of diameter measurement.

Method the most according to claim 1, it is characterised in that laser beam emitting device S1 in step 1, Distance L between S2 should meet: 840mm < L < 3140mm, i.e. L should be greater than the diameter value of standard wheels pair, Prevent the laser that S1 Yu S2 launch and beat the situation on wheel simultaneously, cause interference between laser and Seasonal effect in time series is chaotic, and L should be less than the diameter value of wheelbase and standard wheels pair before and after bogie and value, Make a wheel during measuring, not have another wheel and enter the detection region of S1.

Method the most according to claim 1, it is characterised in that the laser beam in step 2 and horizontal sextant angle α₁、 α₂Should meet: the laser that S1, S2 launch is radiated at inside wheel, facular height is less than the wheel center of circle, is higher than Rail level and will not being irradiated on brake block and other underbody devices of wheel.

Method the most according to claim 1, it is characterised in that the wheel medial surface in step 2 is: with The plummet face at the centrage place of track is parallel, translates face, 70mm place inside track.

Method the most according to claim 1, it is characterised in that the time series in step 3 has following four The individual moment is constituted successively: 1. R1 is by the moment t of " ON-OFF "₁；2. R1 is by " cut-off conducting " Moment t₂；3. R2 is by the moment t of " ON-OFF "₃；4. R2 is by the moment t of " cut-off conducting "₄。

Method the most according to claim 1, it is characterised in that the instantaneous when wheel in step 4 passes through Speed is calculated by the following step:

1st step, obtains distance L between laser beam emitting device S1, S2 according to step 1；

2nd step, obtains wheel according to step 3 and starts to block the moment t of S1₁With start to block the moment t of S2₃, And spacing L of S1, S2 laser beam tries to achieve an Instantaneous velocity values V₁；The moment of S1 is left according to wheel t₂With the moment t leaving S2₄, and spacing L of S1, S2 laser beam tries to achieve an Instantaneous velocity values V₂, its In:

$V_1=\frac{L}{t_3-t_1}$

$V_2=\frac{L}{t_4-t_2}$

3rd step, to speed V₁、V₂This wheel of acquisition of averaging blocks S1 to finally walking out S2 range from starting The average speed of period

$\stackrel{\&OverBar;}{v}=\frac{V_1+V_2}{2}=\frac{1}{2}(\frac{L}{t_3-t_1}+\frac{L}{t_4-t_2}).$

Method the most according to claim 1, it is characterised in that the acquisition side of the wheel diameter in step 5 Method is as follows:

1st step, according to step 4 obtain wheel by time average speed

2nd step, obtains wheel according to step 3 and starts to block the moment t of S1₁With the moment t leaving S1₂, try to achieve Chord length l that S1 streaks on wheel₁；Obtain wheel according to step 3 and start to block the moment t of S2₃With from Open the moment t of S2₄, try to achieve chord length l that S2 streaks on wheel₂, wherein:

$l_1=(t_2-t_1)\&CenterDot;\stackrel{\&OverBar;}{v}$

$l_2=(t_4-t_3)\&CenterDot;\stackrel{\&OverBar;}{v}$

3rd step, if wheel rim apex circle radius is R, wheel rim height is known as h, tries to achieve S1 laser at wheel medial surface On streak track distance the wheel center of circle vertical height be R-H₁-h, can be passed through Pythagorean theorem by chord length Try to achieve one radius R of wheel rim apex circle₁, the wheel rim apex circle diameter of twice deducts the wheel rim height h of twice again and tries to achieve Wheel diameter r₁, i.e. pass through Pythagorean theorem

$R^2={(R-H_1-h)}^2+{\left(\frac{l_1}{2}\right)}^2$

The wheel rim apex circle radius value trying to achieve wheel is:

$R_1=\frac{H_1+h}{2}+\frac{l_1^2}{8(H_1+h)}$

The wheel rim apex circle diameter of twice deducts the wheel rim height h of twice again and tries to achieve wheel diameter r₁

$r_1=2R_1-2h=H_1-h+\frac{l_1^2}{4(H_1+h)}$

In like manner, the vertical height in the track distance wheel center of circle that S2 laser streaks on wheel medial surface is R-H₂-h, is tried to achieve wheel rim apex circle another radius R by chord length by Pythagorean theorem₂, the wheel rim summit of twice Circular diameter deducts the wheel rim height h of twice again can be in the hope of wheel diameter r₂, i.e. pass through Pythagorean theorem

$R^2={(R-H_2-h)}^2+{\left(\frac{l_2}{2}\right)}^2$

Another wheel rim apex circle radius trying to achieve wheel is:

$R_2=\frac{H_2+h}{2}+\frac{l_2^2}{8(H_2+h)}$

The wheel rim apex circle diameter of twice deducts the wheel rim height h of twice again and tries to achieve wheel diameter r₂:

$r_2=2R_2-2h=H_2-h+\frac{l_2^2}{4(H_2+h)}$

Two the wheel diameter values obtained in 3rd step are averaging reduction error, its meansigma methods conduct by the 4th step Wheel diameter r:

$r=\frac{r_1+r_2}{2}-h+\frac{l_1^2}{4(H_1+h)}+\frac{l_2^2}{4(H_2+h)}.$

9. the system of a train wheel diameter detection, it is characterised in that include two with CPU Laser beam emitting device and laser receiver, along train direction of advance, two laser of side installation in orbit are sent out Injection device, is designated as S1, S2 respectively, and two laser beam emitting devices are on same straight line and be parallel to track and prolong Stretch direction, outside the vertical direction that the laser that laser beam emitting device is launched extends along track is by directive track inside track Side；Two laser receivers are installed outside track successively, are designated as R1, R2, two laser receivers In the same vertical plane and this vertical plane is parallel to track bearing of trend, and R1 receives the laser that S1 sends, R2 receives the laser that S2 sends；The laser of S1, S2 transmitting and the water being perpendicular to face, track bearing of trend place Horizontal line angle is respectively α₁、α₂, laser beam emitting device S1, S2 are between same level height and laser beam Spacing be L, the height at laser beam emitting device S1, S2 place less than orbit plane to ensure that Laser emission sets The standby safety with train；

Place a wheel for demarcation in orbit right, it is thus achieved that the laser that S1 launches stays on wheel medial surface Under hot spot be H to track upper surface horizontal plane height₁, the laser that S2 launches stays on wheel medial surface Under hot spot be H to track upper surface horizontal plane height₂；

When wheel is through out-of-date, laser receiver R1, R2 can experience " ON-OFF conducting " respectively State, laser receiver record each state change moment, each wheel can obtain by four moment One group of time series of data composition；

Described CPU includes car speed acquisition module and wheel diameter acquisition module, at car speed In acquisition module, when the position that train is installed through laser sensor, according to laser beam emitting device S1, S2 Spacing L and state change time time data, obtain wheel by equipment time instantaneous velocity；At car In wheel diameter acquisition module, according to train instantaneous velocity, in conjunction with wheel by time moment, obtain laser and beat Chord length on wheel, thus it is calculated wheel diameter.