RU2293671C2 - Methods of and device for determining speed of rail vehicle - Google Patents

Abstract

FIELD: railway transport; rail vehicle control systems.

SUBSTANCE: proposed method is based on calculated of peripheral speed and acceleration of all wheelsets, measuring linear acceleration in direction of vehicle movement, setting of driving conditions and calculation of vehicle speed at acceleration and braking. Proposed device contains four wheelset speed transducers whose outputs are connected with corresponding inputs of four differentiators, longitudinal linear acceleration transducer, unit generating vehicle motion signal and unit determining maximum and minimum speeds of wheelsets. Inputs of units determining maximum and minimum speeds of wheelsets are coupled with outputs of wheelset speed transducers. Device contains two compensating linear acceleration transducers, speed calculating and vehicle acceleration calculating units, two units generating corrections for calculation of acceleration of vehicles.

EFFECT: provision of efficiency of acceleration and braking process in wide range of change of adhesion coefficient owing to more accurate accounting of slipping or wedging of wheel and also protection of wheel roll surfaces from slides and well pads.

5 cl, 1 dwg

Description

The invention relates to the field of vehicle control systems, in particular rail transport.

The predominant use of the invention is a control system for the movement of passenger and freight rail transport.

The current stage of development of rail vehicles is characterized by an ever-increasing introduction of automated and automatic control systems on them, providing them with higher performance indicators.

One of the directions of this development is associated with the creation of adaptive systems of acceleration and braking, which automate the regulation of wheel slippage. This makes it possible to prevent slipping or blocking of wheels on rails with a high slip coefficient, to achieve the best grip in various operating conditions, and therefore to realize optimal vehicle deceleration and braking distance.

The use of such control systems in vehicles, called anti-slip and anti-lock systems, provides not only the efficiency of the acceleration and braking process in a wide range of adhesion coefficients, but also due to the exclusion of slipping or jamming of the wheel, it protects the surface of the wheels from sliders and fat. The latter circumstance is extremely important for railway transport, since violation of the wheel's rolling surface has a harmful destructive effect both on the running gear and on the railway track.

One of the most important problems when creating anti-lock and traction control systems is the accuracy of measuring the degree of slippage of wheel sets, which is associated with the need to accurately measure vehicle speed.

Known motion control systems in which the speed of the vehicle uses the speed of the wheelset, which currently has the lowest (in acceleration mode) or highest (in braking mode) rotation speed [1, 2]. However, since all wheel sets are always in conditions of the engine torque or braking force acting on them, the use of this method does not allow to measure the actual vehicle speed with the necessary degree of accuracy.

Known control systems in which the task of determining the speed of a vehicle is solved by comparing the angular speeds of rotation of braking and freely rotating wheel pairs. The disadvantage is obvious - not all wheels are involved in acceleration or braking and, therefore, their effectiveness is reduced.

There are also known methods of measuring vehicle speed, based on the use of location-based methods of measuring speed, as well as methods of calculating speed based on information about linear acceleration in the direction of vehicle movement [3, 4, 5]. The first methods are very expensive and practically unsuitable for rail transport. The methods for calculating the vehicle speed based on linear acceleration measurements require solving such problems as:

- compensation of the component of the acceleration of gravity due to the non-horizontal road (path);

- choosing the moment of setting the initial vehicle speed in the integration procedure;

- compensation for cumulative errors due to the presence of errors of the linear acceleration sensor.

In this regard, in modern control systems, the indirect method for calculating the vehicle speed V _tf [4] is most widely used, in accordance with the expression:

- среднее ускорение колесных пар;Where

- average acceleration of wheel sets;

[a _to (t)] _i is the acceleration of the i-th wheel;

(V _k ) _m is the peripheral speed of the wheel corresponding to the minimum (during acceleration) or maximum (during braking) of the peripheral speeds of the wheels (wheelsets) at the beginning of this mode of movement;

t _n - the moment of the beginning of the corresponding mode of movement;

t is the vehicle travel time.

It is easy to see that this method gives an overestimated (during acceleration) or underestimated (during braking) value of the speed V _tf , since in acceleration mode the acceleration of the wheel is always greater than the acceleration of the vehicle, and in braking mode it is always less than it.

The objective of the invention is to eliminate the above disadvantages of the currently existing methods of measuring vehicle speed.

For a more accurate measurement of the vehicle speed (in acceleration and braking modes) in the claimed method, it is proposed to calculate it in accordance with the expression:

where a _tf is the acceleration of the vehicle.

In the steady-state mode (on coast), the vehicle speed is proposed to be calculated in accordance with the expression V _tc = (V _k ) _max , where (V _k ) _max is the maximum circumferential speed of the wheelset.

In order to exclude the influence of the path inclination on the measurement accuracy, the vehicle’s acceleration in this method proposes to measure three linear accelerations: one in the direction of the vehicle’s movement and two additional (compensation) accelerations in the directions located at an angle of ± α (for example, ± 45 °) to the direction of movement. In this case, the vehicle acceleration a _{tc is} calculated in accordance with the following expression:

where a ₀ - linear acceleration in the direction of movement of the vehicle;

a ₁ , a ₂ - compensation linear acceleration.

The choice of the sign in the expression for determining a _tf is determined based on the expression:

Where

To compensate for the errors of linear acceleration sensors (a ₀ , a ₁ , a ₂ ) and to exclude their influence on the accuracy of calculating the vehicle speed in the present method, it is proposed to use a correction method based on periodic (over time T _p ) removal of torque (in acceleration mode) or braking (braking mode) at the moment of time (T _p) which is sufficient to bring the peripheral speed and the wheel acceleration to the speed and acceleration of the vehicle and calculating the adjusted value of the vehicle speed in accordance with the expression V _are | _y = V _n , where V _tf | _y is the speed of the vehicle at the time of refinement, V _n is the peripheral speed of a freely rotating wheelset. In this case, the speed value (V _tf | _y ) is used as the initial value in expression (2) to calculate the speed of the vehicle until the moment the speed is updated again. Due to the fact that at the time of specifying the speed V _{tc, the} acceleration of a freely rotating wheel pair is equal to the acceleration of the vehicle, the proposed method proposes to calculate the correction (a _pop1 ) to the calculation of the acceleration of the vehicle (in accordance with expression (3)) by the formula a _pop1 = a _kn | s _{at ts,} where a _book | _y is the acceleration of the non-braking wheelset at the time of refinement, and calculate the value of a _TC in accordance with the expression:

where (a _tf ) _o is the value of the acceleration of the vehicle, calculated in accordance with expression (3).

In this case, the value of the correction (a _pop1 ) remains unchanged until the moment of the next refinement.

The studies showed that the time T _p should be in the range of 6 ... 8 s, and the time T _P should be 1.5 ... 2.0 s.

Due to the fact that to ensure the necessary accuracy in calculating the vehicle speed V _tf , a very high degree of accuracy of installation of the linear acceleration sensor and _about the direction of movement of the vehicle is required, the claimed method proposes a system for compensating for the inaccuracy of its installation, based on measurement in stop mode vehicle (at V _tf = 0) amendments (a _pop2 ) in accordance with the expression:

where N is the number of measurements of the linear acceleration of the vehicle and taking this correction into account when calculating the acceleration of the vehicle.

In this case, expression (5) will take the following form:

A device that implements this method of determining the speed of a rail vehicle is shown in FIG.

It includes four wheel speed sensors 1 ... 4, the outputs of which are connected to the corresponding inputs of four differentiators 5 ... 8, a longitudinal linear acceleration sensor 9, a unit for specifying the driving mode of the vehicle 10, a unit for determining the minimum and maximum speeds of the wheel pairs 11 , the inputs of which are connected with the outputs of the wheel speed sensors 1 ... 4, two compensation linear acceleration sensors 12 and 13, blocks for calculating the speed 14 and acceleration 15 of the vehicle, two blocks for generating corrections for calculating the accelerator vehicle 16 and 17, the outputs of which are connected to the corresponding inputs of the acceleration calculation unit 15, the vehicle speed and acceleration timing selection unit 18, the input of which is connected to the output of the driving mode setting unit 10, and the output is connected to the corresponding inputs of the amendment generating unit 16 and unit 14 for calculating the vehicle speed and the block for generating control signals 19, the inputs of which are connected to the outputs of the block for selecting the moment of refinement 18 and the block for setting the driving mode 10.

The output unit for determining the minimum and maximum speeds of the wheelsets 11 is connected to the input of the unit for calculating the speed of the vehicle 14.

The outputs of the rotation sensors of the wheelsets 1 ... 4 and the differentiators 5 ... 8 are connected to the corresponding inputs of the vehicle speed calculation unit 14. The outputs of the linear acceleration sensors 9, 12, 13 are connected to the corresponding inputs of the vehicle acceleration calculation unit 15, and the output block 15 is connected to the corresponding inputs of the unit for calculating the speed of the vehicle 14 and the second input of the block 16.

The third input of block 16 is connected to the output of the longitudinal linear acceleration sensor 9, and its fourth input is connected to the output of the block for setting the driving mode 10.

The inputs of the correction generating unit 17 are connected to the outputs of the longitudinal linear acceleration sensor 9, the motion mode setting unit 10 and the speed calculating unit 14, and the output of the block 10 is also connected to the corresponding input of the speed calculating unit 14.

The operation of the device for determining the speed of a rail vehicle in all driving modes occurs in the following sequence.

In parking mode

When the vehicle is parked, the “Parking” signal is generated at the output of block 10, which is fed to the input of the speed calculation unit 14. At the same time, the signal V _tc = 0 is generated at the output of block 14, which is fed to the input of the calculation calculation block of amendment 17. During the entire parking time in block 17 is calculated (in accordance with expression 6) the value of a _pop2 . At the moment of starting, block 10 generates a “acceleration” signal, upon receipt of which calculation 17 ends in block 17 and _pop2 , its value is stored until the next stop and goes to the input of acceleration calculation block 15.

In overclocking mode

The “acceleration” signal from the output of block 10 also arrives at the inputs of blocks 14, 16, 18, and 19. At the time of its arrival, the initial value of the correction a _pop2 = 0 is generated at the output of block 16, a timer is started in block 18, which counts the time T _p until the next refinement of the speed and acceleration of the vehicle.

Since the beginning of the movement of the linear acceleration signals from the outputs of the sensors 9, 12 and 13 are fed to the inputs 15, whose output signal is generated and the vehicle acceleration _are calculated in accordance with expression (7).

The signal a _tc from the output of block 15 is fed to the input of block 14, the remaining inputs of which receive signals of peripheral speed (V _k ) and acceleration (a _k ) of the wheel pairs from sensors 1 ... 4 and differentiators 5 ... 8. The signals V _k from the outputs of the sensors 1 ... 4 are fed to the input of block 11, where the minimum and maximum values of the peripheral speed of the wheelsets of the vehicle are determined, which also go to the input of block 14. At the output of block 14, in accordance with expressions (3) and (4) a vehicle speed signal V _tf is generated.

After the time T _{p has passed,} at the output of block 18, a signal “start of the refinement mode” is generated, which is fed to the input of the block for generating control commands 19. Upon receipt of this signal and the presence of a signal of the presence of the “acceleration” mode at the second input of block 19, a command is generated at its output engine shutdown on one of the axles of the vehicle. At the same time, in block 18, a timer starts, counting the time T _p sufficient to brake the wheelset to the vehicle speed.

At the end of time T _p, the output of block 18 generates a signal "end of the refinement mode", which is fed to the inputs of the block for generating control commands 19, the block for generating amendments 16 and the block for calculating the speed of the vehicle 14. At the same time, the output of block 19 generates a command to turn off engine, in block 16 calculates the new value of the correction a _pop1 and in block 14 in accordance with the expression V _TC | _y = V _{n the} calculated value of the vehicle speed is calculated, which is subsequently used as the initial value in the calculation of V _tf in accordance with expression (2).

Steady state

In the "steady-state motion" mode (in the absence of acceleration and braking modes) determined by block 10, the speed of the vehicle, the signal of which is generated at the output of block 14, is equal to the maximum peripheral speed of the wheelset entering block 14 from the output of block 11.

In braking mode

In the braking mode, the presence signal of which is generated at the output of block 10, the operation of the vehicle speed detecting device V _{tc is} similar to its operation in the braking mode, except that at the end of the time T _p , a command is generated at the output of block 19 to disable the braking of one of the wheel steam, which is removed after time T _r .

At the same time, in block 16, a new correction value a _{pop1 is calculated} , and in block 14, in accordance with the expression V _tc | _y = V _{n the} calculated value of the vehicle speed is calculated, which is subsequently used as the initial value in the calculation of V _tf in accordance with expression (2).

The proposed device is currently implemented on the Sokol-250 experimental high-speed electric train and its tests have confirmed the effectiveness of the solutions incorporated into it.

Information sources

1. L.V. Gutkin, Yu.N. Dymant, A.I. Ivanov. "Electric train ER 200". - M.: Transport, 1981, 192 p.

2. Copyright certificate No. 1772022, USSR.

3. Frumkin A.K., Popov A.I., Alyshev I.I. Modern anti-lock braking and traction control systems for trucks, buses, trailers. - M.: TSNIITEIavtoprom, 1990.

4. Technical description of the anti-lock braking system of SAB WABCO company - High Performances New Generation, SWS2000 Wheel Slide Protection Equipment, 1996 - prototype.

5. ABS / ASR “D” - Anti-lock braking system for trucks and buses, WABCO Fahrzeugbremsen, 1999 (Copyright WABCO 1998).

Claims (5)

1. The method of determining the speed of a rail vehicle, based on the calculation of the peripheral speed and acceleration of all wheelsets, measuring the linear acceleration in the direction of movement of the vehicle, setting the mode of its movement and calculating the speed of the vehicle in acceleration and braking modes in accordance with the expression:

where (V _to ) _about - the speed of the wheelset at the time of the start of acceleration or braking; and _TC - acceleration of the vehicle; t _n - the moment of the start of acceleration or braking, and in the steady-state mode V _{tf is} calculated in accordance with the expression V _tf = (V _k ) _max ), where (V _k ) _max is the maximum of the peripheral speeds of the wheelsets, characterized in that it is measured in two directions of acceleration compensation, offset in the vertical plane with respect to the vehicle travel direction at an angle of ± α, and calculating the vehicle acceleration (a _n) in accordance with the following expression:

where a ₀ is the linear acceleration measured in the direction of movement of the vehicle; and ₁ a ₂ - compensation linear acceleration; g is the acceleration of gravity; α is the installation angle of the compensation sensors; and _pop1 and a _pop2 are correction values, while the sign in the expression for determining a _tf is determined according to the expression:

Where

(a _k ) _cf is the average acceleration of braking of the wheelsets. 2. A method according to claim 1, characterized in that the vehicle braking mode periodically (after the time T _n1) to remove the braking force from one wheel pair at a time (T _p1), for a sufficient acceleration to its true speed, vehicle speed equate means to the speed of non-braking wheelset in accordance with the expression V _TC | _y1 = V _n1 , where V _tf | _y1 - vehicle speed at the time of clarification; V _n1 - the _peripheral speed of the non-braking wheelset, and calculate the correction (a _pop1 ) to calculate the acceleration of the vehicle in accordance with the expression a _pop1 = a _kn | _{y1-a tc} , where a _kn | _y1 is the acceleration of the non-braking wheelset at the time of refinement, while the correction value (a _pop1 ) remains unchanged until the next refinement. 3. A method according to claim 1, characterized in that in the acceleration mode, the vehicle periodically (after the time T _n2) remove torque from one wheel pair at a time (T _p2) sufficient for its deceleration to the true velocity, vehicle speed equate means for speed of non-accelerated wheelset in accordance with the expression V _tf | _{y2 =} V _n2 where V _tf | _y2 - vehicle speed at the time of refinement; V _n2 is the peripheral speed of the non-accelerating wheelset, and calculate the correction (a _pop1 ) to calculate the acceleration of the vehicle in accordance with the expression a _pop1 = a _kn | _{y2-a tc} , where a _KN | _y2 is the acceleration of the non-accelerating wheelset at the time of refinement, while the correction value (a _pop1 ) remains unchanged until the next refinement. 4. A method according to claim 1, characterized in that the stop mode of the vehicle (at V = 0 _tf) calculating a correction (a _pop2) for linear acceleration measurement inaccuracy in the direction of vehicle movement ₍₀₎ in accordance with the expression:

where N is the number of measurements of the linear acceleration of the vehicle. 5. A device for determining the speed of a rail vehicle, comprising four wheel pair speed sensors, the outputs of which are connected to the respective inputs of four differentiators, a longitudinal linear acceleration sensor, a vehicle driving mode signal generating unit and a maximum and minimum wheel pair speed determination unit, the inputs of which are connected with the outputs of the wheel speed sensors, characterized in that two compensation linear acceleration sensors are introduced into it, blocks of calculation vehicle speed and acceleration, two blocks for generating corrections for calculating the vehicle’s acceleration, the outputs of which are connected to the corresponding inputs of the acceleration calculating unit, a unit for selecting the moment for updating the vehicle’s speed and acceleration, the input of which is connected to the output of the driving mode setting unit, and the output is connected with the corresponding inputs of the first amendment generating unit and the vehicle speed calculating unit, the control signal generating unit, the inputs of which are connected to the odes of the driving moment selection unit and the driving mode setting unit, the output of the maximum and minimum wheel pair determination unit being connected to the corresponding input of the vehicle speed calculating unit, the outputs of the wheel pair speed sensors and differentiators connected to the corresponding inputs of the vehicle speed calculating unit, the sensor outputs linear acceleration are associated with the corresponding inputs of the vehicle acceleration calculation unit, the output of the calculation unit is accelerated it is connected to the corresponding inputs of the vehicle speed calculating unit and the second input of the first amendment generating unit, its third input is connected to the output of the longitudinal linear acceleration sensor, and its fourth input is connected to the output of the driving mode setting unit, while the inputs of the second amendment generating unit are connected with the outputs of the longitudinal linear acceleration sensor, the motion mode setting unit and the speed calculation unit, and the output of the motion mode setting unit is connected to the corresponding input of the calculation unit speed.