RU2549607C1 - Device to detect distance travelled by ground vehicle - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: invention relates to the field of instrument making and may find application in systems to detect travelled path of ground vehicles. A mechanical speed sensor and an optoelectronic speed sensor are interconnected. In process of vehicle motion they measure time of delay in reception of signals by light-sensitive elements of the optoelectronic sensor that are reflected from irregularities of road surface, as they are illuminated with a mini-projector of a moving object. At the same time the optoelectronic speed sensor estimates not the entire combination of pulses arriving from its sensitive elements, but just specific pulses released into predicted intervals of time with the help of the mechanical speed sensor. With this purpose the device includes the following: a trigger, a logical element, a generator, a pulse counter, a calculator and an integrating device.

EFFECT: increased accuracy compared to systems, where for travelled path measurement they use only a mechanical travel sensor.

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Description

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

Integrated navigation systems (SPS), due to the excess information available in them, the availability of appropriate corrective tools and the automatic processing of redundant information, are more accurate than any of the meters separately.

There are many implementations of SPS for land vehicles, in which meters are used to determine the distance traveled, based on various physical principles for determining motion parameters: a mechanical track / speed sensor (MDP / MDS), a Doppler speed sensor (DDS), linear acceleration meters (accelerometers) ), correlation-extreme speed meters, etc.

It should be noted that in most cases, the structurally existing MIS and MDS are very close, 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.

Also known optoelectronic speed sensor (OEDS) [1]. The principle of its operation 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 the OEDS, the outputs of which (optoelectronic arrays) receive the light fluxes Ф (t) and Ф (t + τ).

The optoelectronic arrays are mounted on the NTS and are separated in space by a strictly defined distance ℓ _B relative to each other in the longitudinal direction along the direction of the NTS. Then the speed V of the motion of the NTS can be determined in accordance with the formula:

V _oeds = ℓ _B / τ.

The main difference between the principle of operation of OEDS from other close ones according to the principles of measuring speed, for example, from correlation-extreme speed meters [2], is that not all the signals at the outputs of both channels of OEDS are evaluated, but only individual characteristic pulses having sufficiently large amplitudes reflected pulses.

A device is known for measuring the distance of the fighter’s base as an integral part of the ground navigation system, in which, when measuring the distance traveled, a mechanical and two Doppler speed sensors are integrated [3]. Moreover, the MDS is used at low speeds of the NTS, when the DDS give a large error in measuring speed.

The closest invention (prototype) in technical essence is a device for measuring the distance traveled by a car [4], which performs the correction of the scale factor of a mechanical track sensor based on an analysis of the sign and magnitude of the vehicle’s acceleration determined by a linear acceleration sensor (accelerometer).

This device for measuring the distance traveled by a car contains a track sensor mounted on a wheel, a track counter made in the form of a pulse generator, a comparison circuit, a software switch, a pulse counter and an indicator, the output of the track sensor is connected through a pulse generator to the first input of the comparison circuit, the output the software switch is connected to the second input of the comparison circuit, the output of which through the pulse counter is connected to the indicator input, a block for analyzing the movement conditions, consisting of a linear sensor accelerations, an NAND element, first and second diodes, n-first threshold devices, n-second threshold devices, a signal picker, the output of the path sensor being connected via a pulse generator to the first input of the comparison circuit, the output of the software switch connected to the second input of the comparison circuit , the output of which through the counter is connected to the indicator input, the output of the linear acceleration sensor is simultaneously connected through the NAND element, the first directly connected diode and the second back-connected diode, respectively, with the first software input switch, the first inputs of the n-first threshold devices and the first inputs of the n-second threshold devices, the n-second inputs of which are connected to the n-outputs of the signal sets, the output of the n-first and second threshold devices are connected respectively to the second and third n-inputs of the software switch .

The signs of this device, which coincide with the essential features of the claimed device, are: a track / speed sensor mounted on a wheel, a pulse generator and a pulse counter.

The disadvantage of this device is the following. It is known from physics that a linear acceleration sensor (accelerometer), which is part of the analysis of motion conditions, measures apparent acceleration [5]. Since this sensor is located on the chassis of the car, not only acceleration in the direction of movement of the car, but also acceleration of gravity in case of an uneven distribution of masses on the front and rear springs will be designed on its sensitivity axis, which almost always takes place (different number of passengers per front and rear seats, cargo in the trunk), as well as when the car is rocking while moving about an axis perpendicular to the direction of movement of the car. So, for example, if the car is standing, and due to the uneven distribution of masses indicated above, the angle of inclination of the longitudinal axis of the car α will be only one degree, then the accelerometer will show acceleration: w = g * sin (α) = 9.91 * 0.017 = 0.17 ms ^{- 2} , where g is the acceleration of gravity. If the car is actually moving with constant acceleration, the distance traveled S, for example for one minute (t = 60 c), up to: S = 0.17 * (60) ^2/2 = 308 m.

The technical task of the proposed device is to increase the accuracy of measuring the distance traveled.

To this end, in the proposed device as an additional measure of the motion parameters of the NTS, an optoelectronic speed sensor is used, which is not affected by the acceleration of gravity. Moreover, to obtain a higher accuracy in determining the distance traveled in comparison with the MDS, it is proposed to use the “temporary” method of combining them in accordance with the previously developed method for determining the speed of a ground vehicle [1].

The signals at the outputs of the OEDS channels are a random sequence of pulses of various durations and amplitudes, since the inhomogeneities of the road surface reflecting the light flux from the emitter are randomly scattered. Therefore, for reliable operation of the OEDS in the NTS, in this method it is proposed to use the predicted time intervals calculated using the MDS readings, in which the pulses at the output of the second OEDS channel should appear after the appearance of the corresponding pulses at the output of the first OEDS channel. This makes it possible to significantly simplify the equipment and facilitate the processing of measurement results by eliminating pulses that do not fall within the expected interval at the output of the second channel of the OEDS.

These predicted time intervals are determined as follows. According to the information received from the MDS in the navigation system as a result of measuring the speed of the NTS at previous times t _i , the predicted speed of the NTS at subsequent times t _{i + 1 is} calculated taking into account the fact that the increment of speed over small periods of time is small. Based on these data, the time intervals are determined in which the pulses at the output of the second channel of the OEDS from the same inhomogeneity of the road surface should fall, following the pulses at the output of the first channel. In other words, the predicted expected time delays between the instants τ _standby signals appear at the outputs of the first and second channels, which is dependent on the speed of movement NTS.

The sequence of expected time delays upon receipt of these pulses is determined by the following formula:

τ _{aw i} = ℓ _B / V _{MDS i} ,

where V _{MDS i} is the speed determined by the MDS information at the i-th moment in time.

Since the exact value of the time of occurrence of the ith expected pulse at the output of the second channel of the OEDS is unknown, it is necessary to determine the boundaries of the time interval into which this pulse Δτ _exp .

Calculations show that this value is inversely proportional to the speed of the NTS and is approximately 30% of the travel time of a distance equal to the base distance ℓ _B. An increase in the value of the time interval Δτ _{ож ож не is} impractical, since the probability of falling into this interval of several false pulses that do not correspond to the true pulse that was at the output of the first channel of the OEDS increases.

If several pulses of similar amplitude are in the given time interval, then this measurement is rejected and the measurement process is repeated.

A device for determining the distance traveled by a land vehicle contains a mechanical speed sensor, a pulse generator G, and a pulse counter ST and differs from the prototype in that a trigger T is introduced, the output of which is connected to the first input of the pulse counter, and the second input of the counter is connected to the output of the pulse generator, an optoelectronic speed sensor, an integrator INT, and an AND logic circuit, connected by its output to the first input of the trigger, the second input of which is connected to the second output of the optoelectro a speed sensor, the first output of which is connected to the second input of the And circuit, the first input of which is connected to the second output of the SR calculator, and its first output is connected to the first input of the optoelectronic speed sensor, the input and output signals of which are fed to the second and third inputs, the output of the counter is connected with the second input of the calculator, the first input of which is connected to the output of the mechanical speed sensor, and the third output of the calculator is connected to the input of the integrator.

The structural diagram of the proposed device is shown in figure 1 and includes the following elements: 1 - MDS; 2 - OEDS; 3 - logical element And; 4 - memory element T (trigger); 5 - pulse generator G; 6 - pulse counter ST; 7 - computing device CP; 8 - integrating device INT.

The device operates as follows: MDS 1 continuously measures the speed of the NTS V _nts (t) and the measurement results from its output V _mds (t) are fed to input 1 of the computing device 7, which based on these measurements has the ability to predict the speed at the following time .

OEDS 2 is connected to start the measurement of V _NTS (t) with its first (along the NTS) SE at discrete time instants by a command coming from a computing device from its output 1. As a result, a signal appears at the output of OEDS 2, which is input 2 of trigger 4, setting it to the “unit” state and allowing its output to start counting pulses from the output of generator 5 in counter 6 at its input 2.

The pulse count in the indicated counter will be performed until the 2nd input of the OEDS 2 at the time t _i + τ is triggered. Moreover, the operation of the specified input should be made in the time interval, which is determined in the calculator and recorded using the command received from output 1. Thus, at the output of counter 6, the number of pulses will be counted, proportional to the delay time of the signals received from the same heterogeneity received by the first and second inputs of the OEDS 2. The obtained values of this meter go to input 2 of the computing device, where they are processed and used in the future generating the specified values of the speed of movement V _oeds (t) at the output 2 of the computing device 7. After integrating this speed with integrator 8, we obtain the distance S _oeds (t) traveled by the NTS.

The physical implementation of this device can be performed on the following element base:

- in OEDS - an optical system with a Zenitar lens (focal length 50 cm), an Aerofon photodetector with a frequency range of 0-10000 Hz, integrated amplifiers of the K-140-UD1 type. As a microprojector installed on the NTS, - halogen lights FAG-1;

- for a high-frequency pulse generator - integrated circuits (IMS) K155TM2, and for a pulse counter - IMS K155LA3;

- for the logic circuit I - IC K555LA3, trigger - IC K155TM2;

- for the computing device and integrator - microprocessor K1810.

Thus, this device provides an increase in the accuracy of measuring the distance traveled by the NTS based on the information obtained as a result of the measurement using MDS and the development of the predicted time intervals in the calculator that are used to measure the OEDS.

Information sources:

1. Kutuzov S.V., Makarov V.A., Kuleshov V.V. Patent 2431847 C1 of the Russian Federation, IPC G01P 3/50 (2006.01) “Method for determining the speed of a ground vehicle”. 2010101941/20. Application 01/22/10. Publ. 10/20/11. Bull. No. 29.

2. Beloglazov I.N., Tarasenko V.P. Correlation-extreme systems. M .: Sov. Radio, 1974.392 s.

3. Solodov V.I. Ground navigation systems. - M .: VA Strategic Rocket Forces named after Peter the Great, 1998, 128 p.

4. Epifanov V.V., Muzhichek S.M. Patent 2300080 C1 of the Russian Federation, IPC G01C 22/00 (2006.01) "A method for measuring the distance traveled by a car, and a device for its implementation." 2005139221/28, 12/15/2005.

5. Command and measuring devices / B.I. Nazarov, V.V. Bulatov, N.P. Lomeyko and others. Under the general. ed. B.I. Nazarova. - M .: MO USSR, 1975.480 s.

Claims (1)

A device for determining the distance traveled by a land vehicle, comprising a mechanical speed sensor, a pulse generator and a pulse counter, characterized in that a trigger is introduced, the output of which is connected to the first input of the pulse counter, and the second input of the counter is connected to the output of the pulse generator, and an optoelectronic speed sensor, integrator and AND logic circuit, connected by its output to the first input of the trigger, the second input of which is connected to the second output of the optoelectronic speed sensor, the first output of which is connected to the second input of the And circuit, the first input of which is connected to the second output of the calculator, and its first output is connected to the first input of the optoelectronic speed sensor, the second and third inputs of which receive input signals, the output of the pulse counter is connected to the second input of the calculator, the first input of which is connected to the output of the mechanical speed sensor, and the third output of the calculator is connected to the input of the integrator.