RU2352918C1 - Device for determination of coefficient of wheel adhesion to artificial pavement - Google Patents

Abstract

FIELD: physics, measurement.

SUBSTANCE: invention is related to devices and systems for assessment of condition of artificial pavement surfaces. Device comprises metering trolley, which contains metering and slave wheels, the first and second increment sensors, microcontroller, electromagnet brake, current detector, controlled power supply source, control panel, memory unit and thermal printer. Metering wheel and one of slave wheels are mechanically connected to accordingly first and second increment sensors. At that the second outlet of metering wheel is mechanically connected to electromagnet brake. The first and second increment detectors are connected to the first and second inlets of microcontroller. The first, second and third outlets of microcontroller are connected to accordingly to inlets of memory unit, controlled power supply source and thermal printer. Control panel is connected to the third inlet of microcontroller. Free inlet of controlled power supply source is inlet of supply voltage source, which is connected to inlet of electromagnet brake via controlled power supply source and current detector. At that the second inlet of current detector is connected to the fourth inlet of microcontroller. Value of coefficient of metering wheel adhesion to surface of artificial pavement is determined by means of measurement of longitudinal adhesion force of metering wheel and surface of artificial pavement, which is produced in process of electromagnet braking, when metering wheel has preset initial stage of skidding (slipping). Device is intended to define coefficient of adhesion on artificial pavements of aerodromes, motor roads, in streets of cities and towns, in sections of limited length and small turn radius.

EFFECT: achievement of efficient definition of adhesion coefficient on artificial pavements of aerodromes, motor roads, in streets of cities and towns, in sections of limited length and small turn radius.

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Description

The invention relates to devices and systems for assessing the surface condition of artificial coatings, including in places where adhesion coefficient measurement is difficult or impossible due to the limited length, small radius of curvature of the road or heavy traffic.

It is known "Device for measuring the coefficient of adhesion of airfield and road surfaces" (Patent No. 2134415 RU, G01N 019/02), which is intended to assess the condition of the road surface mechanically. The device comprises a measuring wheel, which is mounted on a separate frame connected to the rear axle beam by a clamping device. A hinge with a measuring sensor is mounted on the frame. The measuring wheel is connected to the driving wheel through the axle shafts. For vertical load on the measuring wheel in the measuring system of the device there is a load fixed pivotally. The load force is transmitted by a spring shock absorber.

In the known device, the coefficient of adhesion (CSC) is determined by measuring the longitudinal adhesion force (CSC) of the measuring wheel with the surface of the coating with constant slipping. In this case, the coefficient of adhesion is calculated by the formula

CSCP = CSCP / WG,

where Kspp.- coefficient of adhesion of the measuring wheel with the coating surface;

RSCP. - the adhesion force of the measuring wheel with the coating surface with constant slipping;

Rg. - vertical load force on the measuring wheel.

A disadvantage of the known device is that the measuring wheel is forced to constant mechanical sliding on the surface of the coating, which increases the measurement error. In this case, the coefficient of adhesion is measured at a given speed of 50 km / h.

Another known device is the "Device for determining the coefficient of adhesion of the wheel with an airfield coating" (copyright certificate No. 630982, CL G01N 19/02).

The known device comprises a measuring wheel, a locking clutch, a gearbox, a measuring element, a calculator, a control panel, a measuring device, a measuring trolley frame, a central link, a side link, a guide link and a driving wheel.

The determination of the coefficient of adhesion by a known device is that when the measuring trolley moves due to the difference in the diameters of the drive and measuring wheels connected by the gearbox through the blocking clutch, the measuring wheel moves with a predetermined slip relative to the coating. The ratio of the diameters of the driving and measuring wheels provides a given slipping of the measuring wheel. Due to the slipping of the measuring wheel, a longitudinal traction force occurs (RSCP). The coefficient of adhesion is calculated by the well-known formula

CSCP = CSCP / Pr.

A disadvantage of the known device is that when determining the coefficient of adhesion, a speed of 40-50 km / h is set, while the skid of the measuring trolley appears - the lateral braking force appears, which reduces the accuracy of measuring the coefficient of adhesion. The skid of the measuring trolley is due to the presence of different diameters of the measuring and driving wheels.

Closest to the claimed invention in technical essence is “A device for determining the coefficient of adhesion of a wheel with an airfield coating” (Application of the Russian Federation No. 2004137376/11 (001331) - patent No. 2259669, G01P 15/08), therefore this device is taken as a prototype. The structural diagram of the implementation of the known device (prototype) is shown in Fig.1.

Said prototype device comprises a measuring trolley 1 and a registration unit 2.

The measuring trolley 1 includes a measuring wheel 3, driven wheels 4, the first 5 and second 6 angular velocity sensors, an independent vertical load 7, a locking clutch 8, a gear 9, a freewheel 10, a DC generator 11, a voltage regulator 12, a block power keys 13, active load 14, battery 15, contactor 16, starting resistance 17, measuring element 18.

The composition of the registration unit 2 includes a microcontroller 19, a control panel 20, a control unit 21, a memory unit 22, a display 23, and a controller 24.

In this case, an independent vertical load 7 is mechanically connected to the measuring wheel 3, which is mechanically connected to the direct current generator 11 through the blocking clutch 8, the gearbox 9 and the freewheel 10, and the measuring wheel 3 and one of the driven wheels 4 are mechanically connected to the first 5 and second 6 angular velocity sensors. The DC generator 11 through the power switch block 13 is connected to the active load unit 14. The input of the voltage regulator 12 is connected to the power bus of the DC generator 11. The output of the voltage regulator 12 is connected to the second input of the DC generator 11. Power bus of the battery 15 through the contactor 16 and a starting resistance 17 is connected to the input of the DC generator 11. The second output of the battery 15 is connected to the second input of the contactor 16.

The measuring trolley 1 with the registration unit 2 is connected by a flexible cable; the outputs of the first 5 and second 6 angular velocity sensors are connected to the first and second inputs of the microcontroller 19, the output of the contactor 16 is connected to the first input of the control panel 20, the second input of which is connected to the power bus of the generator 11, and the output of the control unit 21 is connected to the second input power key block 13.

Measuring trolley 1 through the measuring element 18 is mechanically connected to the vehicle. The output of the measuring element 18 is connected to the third input of the microcontroller 19.

The control panel 20 is connected to the fourth input of the microcontroller 19. The dynamometer of the power stand is connected to the fifth free input of the microcontroller 19, when calibrating the device. The input / output of the microcontroller 19 is connected to the memory unit 22. The first, second and third outputs of the microcontroller 19 are connected respectively to the control unit 21, the display 23 and the controller 24, to the free input of which external devices are connected. The work of a known device.

Before carrying out work on measuring the coefficient of adhesion, preparatory work is carried out, which is as follows: the lock-up clutch 8 is turned on, the “measurement” mode is turned on, preliminary information is set with the buttons of the control panel 20, and the “Start” button is pressed. The rotor of the DC generator 11 spins up to the nominal rotation speed. After the preparatory work, the towing vehicle accelerates to a speed Va equal to the speed of the measuring wheel 3 when calibrating the device on the power stand. The speed of movement is determined by the speed of rotation of the driven wheel 4.

V = Va; Va = ωr1,

where V is the speed of the measuring wheel 3 on the power stand, m / s;

Va — towing vehicle speed, m / s;

ω is the angular velocity of the driven wheel 4, rad / sec;

r1 is the radius of the driven wheel, m

If the speeds V and Va are equal, the program for determining the maximum longitudinal grip of the tire of the measuring wheel with the surface of the airfield coating is switched on. It should be noted that when the rotation speeds of the output shaft of the gearbox 9 and the rotor of the generator 11 are equal, the freewheel 10 connects the gearbox 9 to the rotor of the generator 11.

The process of determining the maximum coefficient of adhesion (Ksstp.mak.) Is conditionally divided into two stages - search and tracking.

In the search mode, a search is made for the maximum adhesion force (Cmax.) Of the measuring wheel 3 with the surface of the airfield coating. In tracking mode - tracking for maximum traction, while making the necessary adjustments.

The search mode begins with a minimum and uniform increase in current at the active load of unit 14. At the same time, the force PT. dynamic braking of the measuring wheel 3 will also proportionally increase from the minimum value. At the minimum current at the active load 14, when the dynamic braking force PT is less than the adhesion force RSCP of the measuring wheel 3 with the coating surface, the slipping of the measuring wheel 3 is absent. When the load of the generator 11 increases, the dynamic braking force PT increases. With the advent of slipping of the measuring wheel 3, the force of dynamic braking RT. becomes equal to the traction force of the RSCP. measuring wheel with a coating surface. However, the greatest traction force RSCP. poppy. when measuring wheel 3 reaches a slip of 10 to 20%. Increasing the current at the active load 14, we increase the slippage of the measuring wheel 3. And at 10-20% slippage we obtain the maximum value of its dynamic braking Rtmak., Equal to Rsst.mak. In this case, Rtmak. controlled by the readings of the measuring element 18.

Hmac. (RSCP.MAC.) = Ri.-Rk.,

where rt.mak. - maximum dynamic braking force of the measuring wheel 3, N (kg);

RSCP.Mac. - maximum traction force of the measuring wheel 3, N (kg);

Ri. - towing force of the measuring trolley 1, N (kg);

Pk. - rolling resistance force of driven wheels 4, N (kg).

The resistance to rolling Pk. driven wheels is determined on the power stand during calibration of the device or is calculated by the formula

Pk. = GF,

where G is the normal axle load of the driven wheels 4, N (kg);

F is the coefficient of rolling resistance of the driven wheels.

This ends the search mode.

In the tracking mode, when the surface state changes, the current of the active load 14 is increased or decreased, while maintaining the maximum strength of Rtmak. dynamic braking of the measuring wheel 3. The maximum value of the coefficient of adhesion is calculated in accordance with the formula

Kmsp.mak. = Rt.mak. (Rsst.mak.) / Rg.,

where Ksstp.mak. - the maximum value of the coefficient of adhesion;

Rg. - normal (vertical) force of the independent load 7 on the measuring wheel 3, N (kg).

A disadvantage of the known device (prototype) and other known devices is that they cannot assess the condition of the surface of the coating in areas of limited length or with a small turning radius, for example, on aircraft parking lots, in hangars, taxiways of airfields, on the streets of cities and towns .

The purpose of the proposed device is to create a portable device for measuring the coefficient of adhesion, serviced by one person, with the ability to continuously determine the state of coatings of any length, including surfaces with a small turning radius. The goal in the "Device for determining the coefficient of adhesion of the wheel with artificial turf" is achieved by the fact that it, as in the prototype, contains a measuring trolley (figure 2).

The measuring trolley contains a measuring wheel and driven wheels, the first and second incremental sensors, a microcontroller, a control panel and a memory unit. The measuring wheel and one of the driven wheels are mechanically connected respectively to the first and second incremental sensors. The outputs of the first, second incremental sensors and the control panel respectively connect to the first, second and third inputs of the microcontroller, the first output of which is connected to the input of the memory unit,

Additionally, the measuring trolley includes an electromagnetic brake, a current sensor, a controllable power source, and a thermal printer. The measuring wheel is mechanically connected to an electromagnetic brake. The second and third outputs of the microcontroller are connected respectively to a controlled power source and thermal printer. The second free input of the controlled power source is the input of the supply voltage, which is connected to the input of the electromagnetic brake through a controlled power source and then through a current sensor. The second output of the current sensor is connected to the fourth input of the microcontroller. The value of the coefficient of adhesion (K spp.) Of the measuring wheel with the surface of the artificial coating is calculated by determining the longitudinal adhesion force (P spp.) Of the measuring wheel with the surface of the coating obtained by electromagnetic braking, when the measuring wheel has a given initial stage of slipping (slippage), while adhesion coefficient is calculated by the formula

Kscp. = M / (Pr · g),

where is KSCP. - the value of the coefficient of adhesion;

M - torque of the rotor of the electromagnetic brake, Nm;

Rg. - normal load force of the measuring wheel on the surface

coatings, N;

r is the radius of the measuring wheel, m

In the known technical solutions, features similar to the distinguishing features of the claimed device 2 are not found, as a result of which it can be considered that the proposed device corresponds to an inventive step.

Using this device in its implementation will allow you to create a portable device for reliable assessment of the condition of artificial coatings in areas with a limited length and a small turning radius. In this case, a change in the speed of movement and stopping during measurements does not affect the result of the assessment of the surface condition.

The essence of the proposed "Device for determining the coefficient of adhesion of the wheel with artificial turf" is illustrated by drawings, which show:

figure 1 is a structural diagram of a prototype;

figure 2 is a structural diagram of the proposed device;

figure 3 - technical characteristic of the electromagnetic brake 26 - the change in torque M when the current of the coil of the electromagnet;

figure 4 - technical characteristic of the electromagnetic brake 26 - the change in torque M when the rotational speed of the rotor;

figure 5 - algorithm of the proposed device.

The proposed "Device for determining the coefficient of adhesion of the wheels with artificial turf", as well as the prototype, contains a measuring trolley 1.

The measuring trolley 1 comprises a measuring wheel 3 and driven 4 wheels, the first 5 and second 6 incremental sensors, a microcontroller 19, a control panel 20 and a memory unit 22. The measuring wheel 3 and one of the driven wheels 4 are mechanically connected respectively to the first 5 and second 6 incremental sensors. The outputs of the first 5, second 6 incremental sensors and the control panel 20 are respectively connected to the first, second and third inputs of the microcontroller 19, the first output of which is connected to the input of the memory unit 22.

Additionally, the measuring trolley 1 includes an electromagnetic brake 26, a current sensor 27, a controlled power supply 28 and a thermal printer 29. The measuring wheel 3 is mechanically connected to the electromagnetic brake 26. The second and third outputs of the microcontroller 19 are connected respectively to a controlled power source 28 and thermal printer 29. The second free input 25 of the controlled power supply 28 is the input of the power supply voltage, which is connected to the input via a controlled power supply 28, and then through a current sensor 27 in the electromagnetic brake 26, the second output of the current sensor 27 is connected to the fourth input of the microcontroller 19.

The value of the coefficient of adhesion (K spp.) Of the measuring wheel with the surface of the artificial coating is calculated by determining the longitudinal adhesion force (P spp.) Of the measuring wheel with the coating surface obtained by electromagnetic braking, when the measuring wheel has a given initial stage of slipping (slipping), while adhesion coefficient is calculated by the formula

Kscp. = M / (Pr · r),

where is KSCP. - the value of the coefficient of adhesion;

M - torque of the rotor of the electromagnetic brake, Nm;

Rg. - normal load force of the measuring wheel 3 on the surface of the coating, N;

r is the radius of the measuring wheel 3, m

The design of the proposed device.

Measuring trolley 3 has three wheels. Measuring wheel 3 - aviation or automobile chassis and two driven wheels 4 - automobile chassis. The measuring trolley 1 is moved by a person or vehicle. When measuring the coefficient of adhesion, you can change the speed and stop. Changing the speed of movement and stopping does not affect the quality of the measurements. In this case, the maximum speed is specified when calibrating the device.

The measuring wheel 3 and one of the driven wheels 4 are equipped with incremental sensors 5 and 6.

An incremental sensor contains a light source, a tagged disk, a photoresistor assembly, and a signal processing circuit. Incremental sensors 5, 6 are connected to the counting inputs of the microcontroller 19, which is necessary for counting pulses and converting them to the extent of determining the rotation of the measuring 3 and driven 4 wheels. According to the information of incremental sensors 5, 6, the microcontroller 19 determines the distance traveled, the speed of rotation of the wheels and their number of revolutions. Each of the sensors can have a resolution of up to 5000 pulses per revolution. According to the information of the sensors, the start of slipping of the measuring wheel 3 is determined when the torque M of the electromagnetic brake 26 is applied to it.

The microcontroller 19 is based on a PIC18 family microcontroller, which is available with programmable program memory, random access memory, 10-bit analog-to-digital converters, registers, 16-bit timers, built-in interfaces, a real-time timer and corresponding inputs and outputs for input and output of information .

Electromagnetic brake 26 is a magnetic powder brake that combines the elasticity of a hydraulic clutch with the stability of a friction brake. The electromagnetic brake 26 has two coaxial elements: a housing and a rotor. The housing contains an electromagnet coil. The housing from the rotor is separated by an annular gap, which is filled with a special dry alloyed ferromagnetic powder. Powder parameters are resistant to temperature increase. Torque braking torque M is transmitted by doped ferromagnetic powder, the viscosity of which is changed by modulating the current of the coil of an electromagnet. The electromagnetic brake 26 withstands continuous sliding at a set torque value, which is determined by the level of excitation of the electromagnet coil.

The torque M transmitted by the electromagnetic brake 26 is directly proportional to the current of the coil of the electromagnet and varies steplessly from minimum to maximum design value. The technical characteristic of the electromagnetic brake 26 when changing the current of the coil of the electromagnet is presented in figure 3, where: M is the torque of the electromagnetic brake 26, Nm; I is the current of the coil of the electromagnet of the electromagnetic brake 26, and.

The torque transmitted by the electromagnetic brake 26 does not depend on the speed of rotation of its rotor (measuring wheel 3). The technical characteristic of the electromagnetic brake 26 when changing the rotor speed (measuring wheel 3) is shown in Fig. 4, where M is the torque of the electromagnetic brake 26, Nm, V is the rotational speed of the rotor of the electromagnetic brake 26 (measuring wheel 3).

The electromagnetic brake 26 is mechanically connected to the measuring wheel 3. When moving, the measuring wheel 3 rotates - respectively, the rotor of the electromagnetic brake 26 rotates, while the torque M of the brake 26 has a braking effect on the measuring wheel 3.

Taking into account the technical characteristics (on / off time) of the electromagnetic brake 26, the period T is determined. Period T is the time discrete for determining the coefficient of adhesion. The value of the period T is recorded in the memory of the microcontroller 19.

Adjustable power supply 28 changes the current of the coil of the electromagnet of the electromagnetic brake 26, creating a given torque M.

The thermal printer 29 is made in miniature and registers the date, time and place of measurements of the coefficient of adhesion, as well as digitally and graphically displays the state of the surface.

The memory block 22 is made on a non-volatile memory chip. In the memory unit 22 write the date, time, place of measurement, the measured distance and a digital display of the surface condition (CSC). If necessary, the memory unit 22 is removed from the device and connected to the input of a personal computer for a more detailed analysis of the measurements.

The weight of the design of the measuring trolley 1 and the parts of the device is distributed between the measuring 3 and driven 4 wheels of the device. The weight of the design of the measuring trolley 1 and the parts of the device, created on the measuring wheel 3, determines the normal force Pr. measuring wheel 3 on the surface of the coating. The normal strength of Pr. remains constant and is stored in the memory of the microcontroller 19 to calculate the coefficient of adhesion.

The control panel 20. The switches of the control panel 20 include the operating modes of the device: "Measurement - Calibration - Off." Establish preliminary information: date, time and place of measurements.

To the free input 25 of the controlled power source 28 is connected to a constant positive source of supply voltage. As a source of supply voltage, a rechargeable battery or a miniature power plant can be used.

Determination of the coefficient of adhesion (KSCP.) Wheels with the surface of the artificial turf

Before carrying out work on measuring the coefficient of adhesion, preparatory work is carried out: the power source is connected and the operating mode “Measurement” is turned on. Initial information is entered: date, time and place of measurements.

The measuring trolley is driven by a person or vehicle. When moving, the coefficient of adhesion (KSCP.) Is determined in accordance with the software of the microcontroller 19, the algorithm of which is shown in Fig.5.

Moreover, from incremental sensors 5 and 6, the counting inputs of the microcontroller 19 receive pulses in accordance with the rotation speed of the measuring 3 and driven 4 wheels. With the beginning of the movement of the current in the coil of the electromagnet of the electromagnetic brake 26 is absent. The torque force M of the electromagnetic brake 26 is zero, therefore, there is no braking force PT. measuring wheel 3. The measuring wheel 3 rotates without slipping. In the absence of slippage during the period T, the first and second inputs of the microcontroller 19 receive pulses of incremental sensors 5 and 6 in equal amounts. At the end of period T, a trigger pulse is generated in the microcontroller 19, which controls the registers A and B, the comparison process, calculates the distance traveled S and writes information to the memory unit 22 and thermal printer 29.

The pulses of the incremental sensor 5 that arrived during period T are stored in register A, and the pulses of the incremental sensor 6 are stored in register B (registers A and B are the registers of the microcontroller 19). With the arrival of a trigger pulse, the information of registers A and B is compared. If the number of pulses of register A is equal to the number of pulses of register B, then in this case a positive pulse is generated, which enters the summing device. A digital control signal is generated, increased by one, which enters the controlled power source 28. The controlled power source 28 changes the current of the coil of the electromagnet of the electromagnetic brake 26 in accordance with the received digital control signal. In the case under consideration, the current of the coil of the electromagnet increases and the torque M of the electromagnetic brake 26 increases, accordingly, the braking force PT of the measuring wheel 3 increases. If it turns out that the braking force PT of the measuring wheel 3 is less than the adhesion force Rssc. it with the coating surface (RT. <RSCP.), then slipping of the measuring wheel 3 will be absent. In this case, during the period T, from the incremental sensors 5 and 6, the pulses arrive in equal amounts to the first and second inputs of the microcontroller 19. The process is repeated in each period T. In this case, in each period T, the torque M of the electromagnetic brake 26 increases and, accordingly, the braking force PT. measuring wheel 3. The torque M of the electromagnetic brake 26 will increase until the braking force PT. measuring wheel 3 does not become equal to the strength of its adhesion RSC. with the surface of the coating (RT. = RSSC.) or when RT. there will be more RSCP. (RT.> RSC.). Provided that RT. = RSC. or Рт.> Рспп., the slipping of the measuring wheel 3 appears. Moreover, due to the presence of slipping from the incremental sensor 5, less pulses are received in the register A of the microcontroller 19 during the period T. With the arrival of a trigger pulse, the information of registers A and B is compared. The number of pulses in register B will be greater. A negative pulse is generated, which enters the adder. A digital control signal is generated, reduced by one, which enters the controlled power source 28. The controlled power source 28 reduces the current of the coil of the electromagnet of the electromagnetic brake 26 in accordance with the received digital control signal. The torque M of the electromagnetic brake 26 is reduced, respectively, the braking force PT. measuring wheel. A further decrease or increase in the torque M of the electromagnetic brake 26 will depend on the presence or absence of slipping of the measuring wheel 3. The device enters the tracking mode (at a given initial slipping) when the braking force PT. measuring wheel 3 is equal to the traction force

In this case, Pm. = RSCP. = CSCP. Rg. = M / r,

where rt. - braking force of the measuring wheel 3 when exposed to a torque M of the electromagnetic brake 26;

RSCP. - the adhesion force of the measuring wheel 3 with the surface of the coating;

KSCP. - the value of the coefficient of adhesion to the coating surface;

Rg. - normal pressure force of the measuring wheel on the coating surface;

M - torque of the electromagnetic brake 26;

r is the radius of the measuring wheel 3.

The torque M of the electromagnetic brake 26 is determined by the excitation current of the coil of the electromagnet in accordance with the technical characteristics of the electromagnetic brake shown in Fig.3. The current of the coil of the electromagnet of the electromagnetic brake 26 is determined by the current sensor 27. Based on the received torque M and the calibration results, the adhesion coefficient Ksst is calculated. wheels with artificial turf surface. Cohesion coefficient (KSCP.) Is calculated in each period T by the formula

Kskst. = M / (Rg.g),

where is KSCP. - coefficient of adhesion of the measuring wheel 3 with the surface of the artificial turf;

M - torque of the electromagnetic brake 26, Nm;

Rg.- normal pressure force of the measuring wheel 3 on the coating surface, N;

r is the radius of the measuring wheel 3, m. The distance traveled S for the period T is determined by the formula

S = (2πτ / N) n,

where S is the distance traveled by the measuring trolley for the period T (time between start pulses), m;

τ is the radius of the driven wheel, m;

N is the resolution of the incremental sensor 6 (the number of pulses arriving per revolution),

n is the number of pulses received for the period T;

π-3.14 .......

Changing the speed and stop of the measuring cart does not affect the quality of the measurements. During stops, the device captures the previously obtained result and, when the movement resumes, determines the state of the surface from the previously measured value. This moment is displayed on the technical characteristics of the electromagnetic brake 26 shown in Fig.4. In static mode, the torque M is maintained. At the same time, the device must remain on. When measuring the coefficient of adhesion, wetting the surface of the artificial coating is not required. The measurement results are compared with calibration data. If the measurement and calibration results are identical, the obtained information is recorded in the memory unit 22 and in the thermal printer 29.

In the case when, when comparing the measurement results differ from the calibration results of the device, the thermal printer 29 provides information about the malfunction of the device.

Calibration of the device is carried out during its manufacture, and then with a frequency determined by the operating instructions for this device. Calibration of the device is carried out in order to determine the braking force RT. measuring wheel 3 with a calibration of the torque M of the electromagnetic brake 26 when the current of the coil of the electromagnet changes from minimum to maximum values, as well as clarifying the technical characteristics of the device.

For calibration, a well-known device is used - a roller test bench.

The positive effect of the implementation of the proposed device is to create a portable device that will improve the safety of vehicles at modern high-speed modes. A feature of the coefficient of adhesion is the change in its value over time. With prolonged use of artificial coatings, their grip is reduced.

The device can be used by aerodrome services to determine the coefficient of adhesion in aircraft parking lots, in hangars, on taxiways, as well as by organizations that maintain roads and carriageways of streets within cities and towns. Since existing devices for measuring the coefficient of adhesion, due to their design features and conditions of use, cannot be used in areas of limited length and in areas with small turning radii, given that city streets with their heavy traffic are areas with an increased likelihood of traffic accidents , the use of the proposed monitoring device will help to resolve the issue of timely preventive measures.

To implement the proposed device, the following elements can be used:

- measuring wheel 3 — an aircraft or automobile chassis is used;

- incremental sensors 5 and 6 - pulse (step-by-step) encoders from CORRSYS-DATRON;

- microcontroller 19 - microcontroller of the PIC 18 family, description - authors B.Ya. Prokhorenko et al., ed. M., DODEEA, 1999;

- electromagnetic brake 26 - magnetic powder brake, type ELB, Unipack Rus company or magnetic powder brakes, type FAT 650 - FAT 10001 from Mobac GmbH;

- managed power source 28 - a typical device made on transistors and microcircuits;

- memory block 22 - is made on non-volatile memory chips of ATMEL, the author of the description V.V. Grebnev, ed. St. Petersburg, ETF, 1977

Claims (1)

A device for determining the coefficient of adhesion of a wheel with an artificial coating, comprising a measuring trolley that contains a measuring wheel and driven wheels, first and second incremental sensors, a microcontroller, a control panel and a memory unit, while the measuring wheel and one of the driven wheels are mechanically connected respectively to the first and the second incremental sensors, the outputs of the first, second incremental sensors and the control panel are respectively connected to the first, second and third inputs of the microcontrol RA, the first output of which is connected to the input of the memory unit, characterized in that the measuring trolley further comprises an electromagnetic brake, a current sensor, a controllable power supply, a thermal printer, while the measuring wheel is mechanically connected to the electromagnetic brake, and the second and third outputs of the microcontroller are connected respectively to controlled power source and thermal printer, the second free input of the controlled power source is the input of the supply voltage, which through controlled and the power source, and then through the current sensor is connected to the input of the electromagnetic brake, while the second output of the current sensor is connected to the fourth input of the microcontroller, the coefficient of adhesion (RSC) of the measuring wheel with the surface of the artificial coating is determined by determining the longitudinal adhesion force (RSC) of the measuring wheel with the surface of the coating obtained by electromagnetic braking, when the measuring wheel has a given initial stage of slipping (slippage), while the coefficient tsepleniya calculated by the formula
Ksstp = M / (Pr · r)
where KSCP is the value of the coefficient of adhesion;
M - torque of the rotor of the electromagnetic brake, Nm;
Rg is the normal load force of the measuring wheel on the coating surface, N;
r is the radius of the measuring wheel, m

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