RU2624335C1 - Method for autonomous determining ground vehicle speed - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: scale factor of the mechanical speed sensor is calibrated in case of reading deviations of the mechanical and optoelectronic speed sensors exceeding the certain level, according to the information of the mechanical and optoelectronic speed sensor, in which the delay time is measured, when taking it by the light-sensitive elements of the signals reflected from the road surface irregularities, when illuminated with miniprojectors of this sensor. Herewith not all the set of pulses, coming from the sensitive elements, is estimated, but only individual characteristic pulses, that fall within the predictable time intervals defined by the mechanical speed sensor. The measurement periodicity by the highly-accurate measurer is determined by comparing the signal levels of the second channel relative to the first highly-accurate measurer channel, and when the deviations exceed the threshold level, the most highly-accurate measurer is disabled.

EFFECT: improving the accuracy.

Description

The invention relates to the field of ground navigation and can be used in stand-alone ground navigation systems in which it is necessary to determine with high accuracy the speed and distance traveled by a land vehicle (STV). For this, a combination of several meters of motion parameters is used.

Integrated navigation systems (SPS) due to the excess information available in them, the presence of appropriate corrective circuits and automatic processing of navigation information allow to obtain more accurate measurement results of navigation parameters than any single meter [1].

As additional meters can be used meters based on various physical principles for determining the parameters of the motion of the NTS.

There are many implementations of KNS for land vehicles, in which gauges based on various physical principles are used to determine speed: a mechanical speed / path sensor (MDS / MDP) [2, 3], Doppler speed sensors [3], speed meters based on accelerometers [4], extreme correlation speed meters [5], etc. Each of the sensors has its own advantages and disadvantages [2].

The well-known "Method for determining the speed of movement of a land vehicle", where to improve the accuracy of determining the speed of the NTS, the joint work of mechanical and optoelectronic speed sensors (OEDS) is used [6].

The principle of operation of OEDS is based on measuring the delay time τ of the appearance of electrical signals (pulses) at the outputs of the first and second channels of OEDS, the inputs of which (optoelectronic arrays) receive light fluxes Φ (t) and Φ (t + τ).

относительно друг друга в продольном направлении по ходу движения НТС. Тогда скорость V движения НТС может быть определена ОЭДС в соответствии с формулойOptoelectronic arrays are installed on the NTS and are spaced on its chassis at a strictly defined distance

relative to each other in the longitudinal direction along the NTS. Then the speed V of the motion of the NTS can be determined by OEDS in accordance with the formula

.

.

The main difference between the principle of operation of OEDS from other sensors that are close in terms of speed measurement, for example, from correlation-extreme speed meters, is that not all the signals at the outputs of both channels of OEDS are evaluated, but only individual, characteristic pulses having sufficiently large reflected amplitudes signals.

The mechanical speed sensor is a fairly reliable and simple speed meter. Structurally, the currently existing MIS and MDS are no different, the difference between them is only in the adopted algorithm for processing their output signals. So, the number of pulses at the MIS output is proportional to the distance traveled by the MTS, and the number of pulses at the MIS output per unit time is proportional to the speed of the MTS, that is:

where S is the distance traveled by the NTS;

K is the nominal value of the MDS / TIR scale factor stored in the computing device (numerically equal to the distance traveled by the NTS during the time between the two nearest pulses at the output of the MDS / TIR);

N is the number of pulses at the output of the MDS during the movement of the NTS;

V _MDS - the current speed of the NTS, determined by the MDS;

N ^* is the number of pulses per second at the output of the MDS.

However, the MDS has a number of methodological errors in determining the speed [2], one of which is the error due to changes in the radius of the wheel due to pressure violations in the tires during the movement of the NTS. If this sensor is not calibrated during the vehicle’s movement (the scale factor K is not specified), then the speed of the NTS, determined by the MDS during periods when the OED does not function, can differ significantly from the actual [2, p. 86].

The closest in technical essence (prototype) is the "Method for determining the speed of a ground vehicle" [7], which uses the main meter that runs continuously during the movement of the NTS, as well as an additional meter that runs periodically. A mechanical speed sensor is used as the main one, which is a fairly reliable and simple meter with relatively low measurement accuracy. He, in addition, produces the predicted values of the intervals of time intervals during which necessary measurements of the speed of movement should be made by a second more accurate meter. An optoelectronic speed sensor is used as such an additional meter. Moreover, the frequency of measurements with a high-precision meter is determined by comparing the signal levels of the second channel of the high-precision meter relative to the first channel and when they diverge above the threshold level, a higher-precision meter is turned off.

The disadvantages of the considered method are associated, first of all, with the fact that a higher-precision meter cannot work continuously due to the impact on the OEDS of such external adverse operating conditions as the presence of water, ice, fresh snow on the road surface, When the road surface is covered by OEDS mini-projectors the reflected signals from its heterogeneities can be either weak or completely absent. In this case, it is advisable to block the exact speed meter, that is, the OEDS, in order to prevent erroneous correction of the MDS.

Thus, during the movement of the NTS, measurements of navigation parameters made by an accurate optoelectronic meter may be distorted or completely absent under the influence of external adverse road conditions. In the case of an unworkable state of the OEDS or unfavorable road conditions for it (water, sun glare, etc.), it does not measure it, it turns off for a certain period of movement of the NTS. During the motion of the NTS, the accuracy of determining the speed based on MDS also deteriorates due to a change in the scale coefficient of the MDS under the influence of the above reasons.

The aim of the present invention is to improve the accuracy of determining the speed of the STV during periods when the optoelectronic speed sensor is not functioning.

In the proposed method, two speed meters are used - the primary and secondary. In this case, continuous measurement of the object’s speed of movement is carried out by the primary and periodic measurements with high accuracy by additional meters, and at the same time, the measurement of the delay time of the second channel signal relative to the first is used with a high-precision meter at certain boundaries of time intervals previously determined by a less accurate speed meter, and the measurement frequency with high-precision the meter determines based on a comparison of the signal levels of the second channel of the high-precision meter relates As regards the first channel and when they diverge above the threshold level, a more accurate meter is switched off. If the readings of the mechanical and optoelectronic speed sensors exceed a certain level, a constant speed of the ground vehicle during a given period of time is maintained according to the information of the mechanical sensor, the average speed value is determined by the readings of the optoelectronic speed sensor, as well as the average value of the number of pulses per second readings of the mechanical speed sensor, after which the mechanical speed sensor is calibrated.

This calibration is carried out as follows.

If there is a discrepancy in the readings of the mechanical and optoelectronic speed sensors that exceed a certain level, the land vehicle must maintain, according to MDS, a constant speed of the NTS for i time intervals (i = 1, 2, ...). Then for the i-th time interval, you can write:

where V _i - the average speed of the NTS, determined according to the OEDS, during its operation during the i-th time period;

K _i-1 is the nominal value of the MDS / TIR scale factor stored in the computing device until its next calibration at the i-th time interval;

ΔK _i is the increment of the MDS calibration coefficient, which must be determined at the i-th time interval to clarify the MDS / TIR scale factor before its next calibration;

- среднее значение числа импульсов в секунду, определенное по информации МДС в течение i-го промежутка времени. В результате, в соответствии с (2), имеем:

- the average value of the number of pulses per second, determined according to the MDS information during the i-th time interval. As a result, in accordance with (2), we have:

where K _{i + 1} is the new nominal (after MDS calibration) value of the MDS scale factor, which is used in the future (until the next calibration) in the computing device when determining the speed of the NTS according to MDS information.

Information sources

1. Pomykaev I.I., Seleznev V.P., Dmitrichenko A.A. Navigation Devices and Systems: Textbook for High Schools, M.: "Mechanical Engineering", 1983. - 456 p.

2. Popov A.P. Theory of navigation. Part 1. Texts of lectures. M.: USSR Ministry of Defense, 1982.- 196 p.

3. Patent RU 2193755, 2002.

4. Andreev V.D. Theory of inertial navigation. Autonomous systems. M .: "Science", 1966. - 600 p.

5. Beloglazov I.N., Tarasenko V.P. Correlation-extreme systems. M .: Sov. Radio, 1974.- 392 p.

6. Patent RU 2431847, 2011.

7. Patent RU 2552757, 2015.

Claims (1)

A method of autonomously determining the speed of a ground vehicle, which consists in the fact that when using two speed meters of the primary and secondary, continuous measurement of the speed of the object’s movement by the primary and periodic measurement with high accuracy by the secondary meter and using the measurement of the delay time of the second channel signal relative to the first high-precision meter at certain boundaries of time intervals previously determined by less accurate of a speed meter, and the frequency of measurements with a high-precision meter is determined based on a comparison of the signal levels of the second channel of the high-precision meter relative to the first channel and when they diverge above the threshold level, a higher-precision meter is turned off, characterized in that when the difference in the readings of the mechanical and optoelectronic speed sensors exceeds a certain level, a constant speed of the ground vehicle is maintained for a given period of time Information mechanical sensor determined average speed of the optoelectronic speed sensor readings, and the average value of the number of pulses per second by a mechanical speed sensor readings, followed by mechanical calibration of the speed sensor.