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

Method and system for detecting train wheel diameter

technical field

The invention belongs to the technical field of on-line monitoring of rail vehicles, in particular to a method and system for detecting the diameter of a train wheel.

Background technique

In urban rail transit, the wheel is one of the most worn parts in the running gear. The state of the wheels is closely related to the safe operation of the train. For example, the train operation has strict requirements on the size of the wheels, and the use of unqualified wheels will cause safety accidents such as bumps or even derailments during the train operation. Among them, the wheel diameter is one of the important indicators of the wheel state, which has a great influence on the safe operation of the train. Therefore, it is very necessary to detect the wheel diameter.

At present, in terms of wheel set size detection, manual measurement is still widely used. Manual measurement uses a wheel gauge, which is closely related to manual strength, worker proficiency in measurement and site conditions during the measurement process, and there are large errors in manual measurement. On the other hand, due to the large number of train wheels, it takes a lot of time to use manual measurement, and the maintenance efficiency is extremely low.

In recent years, with the development of laser and image technology, a number of non-contact wheel diameter measuring devices and methods have emerged. For example, Chinese patent CN1899904A (on-line detection method and device for train wheel size) utilizes four PSD-based laser displacement sensors to obtain the distance from the end face of the train wheel to the laser detector, and then calculates the rim thickness, rim height, and wheel diameter values . The laser sensor required by this method is expensive, and the installation angle is relatively strict, which is not conducive to large-scale promotion and use.

Contents of the invention

The object of the present invention is to provide a method and system for detecting the diameter of a train wheel with convenient structure layout, fast calculation speed and accurate measurement results.

The technical solution for realizing the purpose of the present invention is: a method and system thereof for train wheel diameter detection, comprising the following steps:

Step 1, sensor layout: install two laser emitting devices on the inner side of the track along the train’s forward direction, denoted as S1 and S2 respectively. The two laser emitting devices are on the same straight line and parallel to the extending direction of the track. The laser emitting devices emit The laser is shot from the inner side of the track to the outer side of the track along the vertical direction of the track extension; two laser receiving devices are installed in sequence on the outer side of the track, denoted as R1 and R2, and the two laser receiving devices are on the same vertical plane and the vertical planes are parallel In the direction of track extension, R1 receives the laser light emitted by S1, and R2 receives the laser light emitted by S2; the angles between the laser light emitted by S1 and S2 and the horizontal line perpendicular to the plane where the track extends are α ₁ and α ₂ , and the laser emitting devices S1, S2 is at the same level and the distance between the laser beams is L, and the height of the laser emitting devices S1 and S2 is lower than the track plane to ensure the safety of the laser emitting equipment and the train;

Step 2, acquisition of installation parameters: place a wheel set for calibration on the track, obtain the vertical height of the laser spot left by the laser emitted by S1 on the inner side of the wheel to the horizontal plane of the upper surface of the track at H ₁ , and the laser emitted by S2 at The vertical height from the light spot left on the inner side of the wheel to the horizontal plane on the upper surface of the track is _H2 ;

Step 3, sensor data acquisition: when the wheels pass by, the laser receiving devices R1 and R2 will respectively experience the state of "on-off-on", and the laser receiving device will record the moment of each state change, and each wheel will Obtain a set of time series consisting of four moment data;

Step 4, vehicle speed acquisition: when the train passes the position where the laser sensor is installed in step 1, according to the distance L between the laser emitting devices S1 and S2 and the time data when the state changes, the instantaneous speed when the wheels pass through the equipment is obtained;

Step 5, wheel diameter acquisition: According to the instantaneous speed of the train obtained in step 4, combined with the moment when the wheel passes, the chord length of the laser hitting the wheel is obtained, and the wheel diameter is calculated.

Compared with the prior art, the present invention has significant advantages: (1) only need to adopt two laser emitting and receiving devices, which saves a lot of cost; (2) the instantaneous speed of the train can be obtained without additional vehicle speed detection device; (3) ) The two laser emitting and receiving devices independently calculate the wheel diameter, and average the results, which can greatly reduce the error; (4) has the advantages of online non-contact measurement, and provides an accurate online measurement of the wheel diameter. Higher degree of solution.

The present invention will be described in further detail below in conjunction with the accompanying drawings.

Description of drawings

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

Fig. 2 is a schematic diagram of sensor installation for wheel diameter detection according to the present invention.

Fig. 3 is a layout diagram of sensors for wheel diameter detection according to the present invention.

Fig. 4 is a sectional view of sensor installation for wheel diameter detection of the present invention.

Fig. 5 is a schematic diagram of the wheel timing sequence of the present invention.

Fig. 6 is an explanatory diagram of the principle of diameter calculation.

detailed description

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

Step 1, sensor layout: As shown in Figure 2, install two laser emitting devices on the inner side of the track along the train's forward direction, denoted as S1 and S2 respectively, and the two laser emitting devices extend on the same straight line and parallel to the track Direction, the laser emitted by the laser emitting device is emitted from the inner side of the track to the outer side of the track along the vertical direction of the track extension; two laser receiving devices are installed in sequence on the outer side of the track, denoted as R1 and R2, and the two laser receiving devices are on the same vertical plane And the vertical plane is parallel to the extending direction of the track, R1 receives the laser light emitted by S1, and R2 receives the laser light emitted by S2; the angles between the laser light emitted by S1 and S2 and the horizontal line on the plane perpendicular to the extending direction of the track are α ₁ , α ₂ respectively , as shown in Figure 3, the laser emitting devices S1, S2 are at the same level and the distance between the laser beams is L, and the height of the laser emitting devices S1, S2 is lower than the track plane to ensure the safety of the laser emitting equipment and the train.

Described laser transmitting device is made up of modulation coding and laser transmitter, and laser receiving device is made up of laser receiver, amplifying detector and modem, and modulation coder modulates the laser of certain frequency and sends out by laser transmitter; When laser receiver receives When using laser, the frequency of the laser will be analyzed by the laser demodulator. When the laser frequency matches, the time of starting and ending the irradiation will be recorded. If the laser frequency does not meet the receiving conditions, it means that the light is noise or interference, which should be filtered out. . The above-mentioned laser "receiving-judgment-recording" process takes less than 30 microseconds to ensure the accuracy of diameter measurement.

The distance L between the laser emitting devices S1 and S2 should satisfy: 840mm<L<3140mm, that is, L should be greater than the diameter value (840mm) of the standard wheel set, so as to prevent the laser emitted by S1 and S2 from hitting the wheel at the same time. The situation will cause interference between lasers and confusion of time series, and L should be less than the sum of the front and rear wheelbase of the bogie (2300mm) and the diameter of the standard wheel set (840mm), so that there will be no other wheel during the measurement of one wheel. A wheel enters the detection area of S1.

Step 2, acquisition of installation parameters: as shown in Figure 4, place a wheel set for calibration on the track, and obtain the vertical height H1 from the light spot left by the laser emitted by S1 on the inner side of the wheel to the horizontal plane of the upper surface _of the track , the vertical height from the light spot left by the laser emitted by S2 on the inner side of the wheel to the horizontal plane of the upper surface of the track is H ₂ . The angles α ₁ and α ₂ between the laser beam and the horizontal should satisfy: the lasers emitted by S1 and S2 are irradiated on the inner side of the wheel, the spot height is lower than the center of the wheel, higher than the rail surface and will not irradiate the brake pads and other underbody devices of the wheel superior. The inner surface of the wheel is: parallel to the plumb surface where the center line of the track is located, and the plane where it is translated 70mm to the inner side of the track.

Step 3, sensor data acquisition: as shown in Figure 5, when the wheels pass by, the laser receiving devices R1 and R2 will respectively experience the state of "conduction-off-conduction", and the laser receiving device records the state changes Time, each wheel will get a set of time series consisting of four time data. The time series is composed of the following four moments in turn: ① R1 from the "on-off" moment t ₁ ; ② R1 from the "off-on" moment t ₂ ; ③ R2 from the "on-off" moment t ₃ ; ④ R2 from the "cut-off" moment t ₄ .

Step 4, Acquisition of vehicle speed: When the train passes the position where the laser sensor is installed in step 1, the instantaneous speed of the wheels passing through the equipment is obtained according to the distance L between the laser emitting devices S1 and S2 and the time data when the state changes. The instantaneous speed when the wheel passes is calculated by the following steps:

The first step is to obtain the distance L between the laser emitting devices S1 and S2 according to step 1;

Step 2, according to step 3, obtain the time t ₁ when the wheel starts to block S1 and the time t ₃ when it starts to block S2, and the distance L between the laser beams of S1 and S2 to obtain an instantaneous speed value V ₁ ; according to the time when the wheel leaves S1 t ₂ and the moment t ₄ when leaving S2, and the distance L between the laser beams of S1 and S2 to obtain an instantaneous velocity value V ₂ , where:

${\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; L</span>}}{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}$

${\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; L</span>}}{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}$

Step 3: Calculate the average of the speeds V ₁ and V ₂ to obtain the average speed of the wheel from the beginning of blocking S1 to the last time when it walks out of the range of S2

$\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; L</span>}}{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; L</span>}}{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; .</span>$

Step 5, wheel diameter acquisition: According to the instantaneous speed of the train obtained in step 4, combined with the moment when the wheel passes, the chord length of the laser hitting the wheel is obtained, and the wheel diameter is calculated. The method of obtaining the wheel diameter is as follows:

Step 1, according to step 4 to get the average speed of the wheel passing

Step 2: According to step 3, obtain the time t ₁ when the wheel starts to cover S1 and the time t ₂ when it leaves S1, and obtain the length l ₁ of a chord that S1 crosses on the wheel; according to step 3, obtain the time t when the wheel starts to block S2 ₃ and the moment t ₄ when leaving S2, obtain the length l ₂ of a chord that S2 draws on the wheel, where:

${\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}$

${\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&Center\; Dot;</span>\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}$

In the third step, the radius of the rim apex circle is set as R, and the rim height is known as h, and the vertical height of the track drawn by the S1 laser on the inner surface of the wheel from the center of the wheel circle is RH ₁ -h, and the chord length can be Obtain a radius R ₁ of the apex circle of the rim through the Pythagorean theorem, and subtract twice the rim height h from twice the diameter of the rim apex circle to obtain the wheel diameter r ₁ , that is, through the Pythagorean theorem

${\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}$

Find the radius value of a rim apex circle of the wheel:

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; )</span>}$

Twice the diameter of the apex circle of the rim minus twice the height h of the rim to obtain the wheel diameter r ₁

${\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; )</span>}$

In the same way, the vertical height of the track drawn by the S2 laser on the inner surface of the wheel from the center of the wheel is RH ₂ -h, and the other radius R ₂ of the rim apex circle is obtained from the chord length through the Pythagorean theorem, twice the rim The diameter r ₂ of the wheel can be obtained by subtracting twice the rim height h from the diameter of the vertex circle, that is, through the Pythagorean theorem

${\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}$

The radius of the vertex circle of the other rim of the wheel is obtained as:

${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; )</span>}$

Twice the diameter of the apex circle of the rim minus twice the height h of the rim to obtain the wheel diameter r ₂ :

${\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; )</span>}$

Step 4, since the two error weights are the same, the average value of the two measurements is taken as the final measurement result of the wheel diameter. The two wheel diameter values obtained in step 3 are averaged to reduce the error, and the average value is used as the train wheel diameter r:

$\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; )</span>}$

With reference to Fig. 2, Fig. 3 and Fig. 4, the device for detecting the diameter of the train wheel of the present invention includes two laser emitting devices and a laser receiving device of the central processing unit, and two laser emitting devices are installed on the inner side of the track along the train's forward direction , denoted as S1 and S2 respectively, the two laser emitting devices are on the same straight line and parallel to the extending direction of the track. Two laser receiving devices, denoted as R1 and R2, the two laser receiving devices are on the same vertical plane and the vertical plane is parallel to the direction of track extension, R1 receives the laser light emitted by S1, and R2 receives the laser light emitted by S2; S1, The angles between the laser emitted by S2 and the horizontal line perpendicular to the plane where the track extends are α ₁ and α ₂ respectively. The laser emitting devices S1 and S2 are at the same level and the distance between the laser beams is L. The laser emitting devices S1 and S2 The height is lower than the track plane to ensure the safety of laser emitting equipment and trains;

Place a wheel set for calibration on the track, and obtain the light spot left by the laser emitted by S1 on the inner side of the wheel to the horizontal plane of the upper surface of the track. The vertical height is H ₁ , and the laser spot left by the laser emitted by S2 The vertical height to the horizontal plane of the upper surface of the track is H ₂ ;

When the wheels pass by, the laser receiving devices R1 and R2 will experience the state of "on-off-on" respectively. The laser receiving device records the moment of each state change, and each wheel will get four time data. A set of time series;

The central processing unit includes a vehicle speed acquisition module and a wheel diameter acquisition module. In the vehicle speed acquisition module, when the train passes the position where the laser sensor is installed, the time data according to the distance L between the laser emitting devices S1 and S2 and the state changes , to obtain the instantaneous speed of the wheel passing through the equipment; in the wheel diameter acquisition module, according to the instantaneous speed of the train, combined with the moment when the wheel passes, the chord length of the laser hitting the wheel is obtained, and the wheel diameter is calculated.

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

Example

Combined with Figure 3 and Figure 4, four laser emitting devices are installed sequentially on the inner side of the track. The position of the emitting device is 0.45m from the inner side of the track, and the angle α is 36°. The measured distance L between the laser beams of the laser emitting devices S1 and S2 is ₁ It is 1.202m. The height of the light spot of S1 on the inner side is H ₁ =215mm, the height of the light spot of S2 on the inner side is H ₂ =213mm, and the rim height of the wheel is known, h=29.3mm.

According to the method of step 3, the train speed is specified to be 5km/h and pass through the equipment, and the time series of the train can be obtained through the equipment. Take one of the sequences for calculation demonstration: t ₁ =1.076s; t ₂ =1.644s; t ₃ =1.942s; t ₄ =2.508s.

According to the method in step 4, combined with the value of L, the instantaneous speed of the train is calculated as:

$\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1.3896</span>}\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; /</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}$

According to the method in step 5, the speed of the train measured in step 3 is brought into the radius calculation formula, and the diameter of the apex circle of the rim of the wheel can be measured as 881.1878mm, and the diameter of the wheel is 822.5878mm. The manually measured value of the calculated wheel diameter is 822.6mm, which shows that this method can effectively and accurately measure the wheel diameter.

Claims (9)

1. a method for train wheel diameter detection, is characterized in that comprising the following steps: Step 1, sensor layout: install two laser emitting devices on the inner side of the track along the train’s forward direction, denoted as S1 and S2 respectively. The two laser emitting devices are on the same straight line and parallel to the extending direction of the track. The laser emitting devices emit The laser is shot from the inner side of the track to the outer side of the track along the vertical direction of the track extension; two laser receiving devices are installed in sequence on the outer side of the track, denoted as R1 and R2, and the two laser receiving devices are on the same vertical plane and the vertical planes are parallel In the direction of track extension, R1 receives the laser light emitted by S1, and R2 receives the laser light emitted by S2; the angles between the laser light emitted by S1 and S2 and the horizontal line perpendicular to the plane where the track extends are α ₁ and α ₂ , and the laser emitting devices S1, S2 is at the same level and the distance between the laser beams is L, and the height of the laser emitting devices S1 and S2 is lower than the track plane to ensure the safety of the laser emitting equipment and the train; Step 2, acquisition of installation parameters: place a wheel set for calibration on the track, obtain the vertical height of the laser spot left by the laser emitted by S1 on the inner side of the wheel to the horizontal plane of the upper surface of the track at H ₁ , and the laser emitted by S2 at The vertical height from the light spot left on the inner side of the wheel to the horizontal plane on the upper surface of the track is _H2 ; Step 3, sensor data acquisition: when the wheels pass by, the laser receiving devices R1 and R2 will respectively experience the state of "on-off-on", and the laser receiving device will record the moment of each state change, and each wheel will Obtain a set of time series consisting of four moment data; Step 4, vehicle speed acquisition: when the train passes the position where the laser sensor is installed in step 1, according to the distance L between the laser emitting devices S1 and S2 and the time data when the state changes, the instantaneous speed when the wheels pass through the equipment is obtained; Step 5, wheel diameter acquisition: According to the instantaneous speed of the train obtained in step 4, combined with the moment when the wheel passes, the chord length of the laser hitting the wheel is obtained, and the wheel diameter is calculated. 2. The method according to claim 1, wherein in step 1, the laser emitting device is composed of a modulation code and a laser transmitter, and the laser receiving device is composed of a laser receiver, an amplifying detector and a modem, and the modulation coder modulates out The laser with a certain frequency is emitted by the laser transmitter; when the laser receiver receives the laser, it will analyze the frequency of the laser through the laser demodulator, and record the time when the laser frequency matches the start and end of irradiation. If it does not meet the receiving conditions, it means that the light is noise or interference and should be filtered out. The above-mentioned laser "receiving-judgment-recording" process takes less than 30 microseconds to ensure the accuracy of diameter measurement. 3. The method according to claim 1, characterized in that the distance L between the laser emitting devices S1 and S2 in step 1 should satisfy: 840mm<L<3140mm, that is, L should be greater than the diameter of the standard wheel set to prevent The lasers emitted by S1 and S2 hit the wheels at the same time, causing interference between the lasers and confusion in the time sequence, and L should be smaller than the sum of the front and rear wheelbase of the bogie and the diameter of the standard wheel set, so that a No other wheel will enter the detection area of the S1 during the wheel measurement. 4. The method according to claim 1, characterized in that the included angles α ₁ and α _{2 between the laser beam and the horizontal in step 2} should satisfy: the laser emitted by S1 and S2 is irradiated on the inner side of the wheel, and the spot height is lower than the center of the wheel, Brake pads and other undercarriage devices that are above the rail surface and do not shine on the wheels. 5. The method according to claim 1, characterized in that the inner surface of the wheel in step 2 is: parallel to the plumb plane where the center line of the track is located, and the plane where it is translated 70mm to the inner side of the track. 6. The method according to claim 1, characterized in that the time sequence in step 3 consists of the following four moments in turn: ①R1 is from the moment t ₁ of "on-off"; ②R1 is from "off-on""Moment t ₂ ; ③ R2 from "on - off" time t ₃ ; ④R2 from "off - on" time t ₄ . 7. The method according to claim 1, wherein the instantaneous speed when the wheel in the step 4 passes is calculated by the following steps: The first step is to obtain the distance L between the laser emitting devices S1 and S2 according to step 1; Step 2, according to step 3, obtain the time t ₁ when the wheel starts to block S1 and the time t ₃ when it starts to block S2, and the distance L between the laser beams of S1 and S2 to obtain an instantaneous speed value V ₁ ; according to the time when the wheel leaves S1 t ₂ and the moment t ₄ when leaving S2, and the distance L between the laser beams of S1 and S2 to obtain an instantaneous velocity value V ₂ , where: ${\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; L</span>}}{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}$ ${\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; L</span>}}{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}$ Step 3: Calculate the average of the speeds V ₁ and V ₂ to obtain the average speed of the wheel from the beginning of blocking S1 to the last time when it walks out of the range of S2 $\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; L</span>}}{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; L</span>}}{{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; .</span>$ 8. The method according to claim 1, characterized in that the acquisition method of the wheel diameter in step 5 is as follows: Step 1, according to step 4 to get the average speed of the wheel passing Step 2: According to step 3, obtain the time t ₁ when the wheel starts to cover S1 and the time t ₂ when it leaves S1, and obtain the length l ₁ of a chord that S1 crosses on the wheel; according to step 3, obtain the time t when the wheel starts to block S2 ₃ and the moment t ₄ when leaving S2, obtain the length l ₂ of a chord that S2 draws on the wheel, where: ${\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}$ ${\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; v</span>}}$ In the third step, the radius of the rim apex circle is set as R, and the rim height is known as h, and the vertical height of the track drawn by the S1 laser on the inner surface of the wheel from the center of the wheel circle is RH ₁ -h, and the chord length can be Obtain a radius R ₁ of the apex circle of the rim through the Pythagorean theorem, and subtract twice the rim height h from twice the diameter of the rim apex circle to obtain the wheel diameter r ₁ , that is, through the Pythagorean theorem ${\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}$ Find the radius value of a rim apex circle of the wheel: ${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; )</span>}$ Twice the diameter of the apex circle of the rim minus twice the height h of the rim to obtain the wheel diameter r ₁ ${\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; )</span>}$ In the same way, the vertical height of the track drawn by the S2 laser on the inner surface of the wheel from the center of the wheel is RH ₂ -h, and the other radius R ₂ of the rim apex circle is obtained from the chord length through the Pythagorean theorem, twice the rim The diameter r ₂ of the wheel can be obtained by subtracting twice the rim height h from the diameter of the vertex circle, that is, through the Pythagorean theorem ${\mathrm{<span\; class="notranslate">\; R</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}$ The radius of the vertex circle of the other rim of the wheel is obtained as: ${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; h</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; )</span>}$ Twice the diameter of the apex circle of the rim minus twice the height h of the rim to obtain the wheel diameter r ₂ : ${\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; )</span>}$ In step 4, the two wheel diameter values obtained in step 3 are averaged to reduce the error, and the average value is used as the wheel diameter r: $\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; h</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; .</span>$ 9. A system for detecting the diameter of a train wheel, characterized in that it includes two laser emitting devices and a laser receiving device with a central processing unit, and along the direction of the train, two laser emitting devices are installed on the inner side of the track, respectively denoted as S1 , S2, the two laser emitting devices are on the same straight line and parallel to the extension direction of the track, the laser emitted by the laser emitting device is shot from the inner side of the track to the outer side of the track along the vertical direction of the track extension; two laser receiving devices are installed in sequence on the outer side of the track , denoted as R1 and R2, the two laser receiving devices are on the same vertical plane and the vertical plane is parallel to the track extension direction, R1 receives the laser light emitted by S1, and R2 receives the laser light emitted by S2; the laser light emitted by S1 and S2 and the The angles between the horizontal lines perpendicular to the plane where the track extends are α ₁ and α ₂ respectively, the laser emitting devices S1 and S2 are at the same level and the distance between the laser beams is L, and the height of the laser emitting devices S1 and S2 is lower than Track planes to ensure the safety of laser firing equipment and trains; Place a wheel set for calibration on the track, and obtain the light spot left by the laser emitted by S1 on the inner side of the wheel to the horizontal plane of the upper surface of the track. The vertical height is H ₁ , and the laser spot left by the laser emitted by S2 The vertical height to the horizontal plane of the upper surface of the track is H ₂ ; When the wheels pass by, the laser receiving devices R1 and R2 will experience the state of "on-off-on" respectively. The laser receiving device records the moment of each state change, and each wheel will get four time data. A set of time series; The central processing unit includes a vehicle speed acquisition module and a wheel diameter acquisition module. In the vehicle speed acquisition module, when the train passes the position where the laser sensor is installed, the time data according to the distance L between the laser emitting devices S1 and S2 and the state changes , to obtain the instantaneous speed of the wheel passing through the equipment; in the wheel diameter acquisition module, according to the instantaneous speed of the train, combined with the moment when the wheel passes, the chord length of the laser hitting the wheel is obtained, and the wheel diameter is calculated.