RU2378705C1 - Method of determining range and/or speed of remote object - Google Patents

Abstract

FIELD: measuring techniques.

SUBSTANCE: invention relates to measuring techniques and can be used particularly for detecting violation of traffic rules by a vehicle. The method involves multiple probing a remote object by sending a series of laser pulses towards it, determining in each probe of the lag between sending the pulses and receiving the radiation reflected by the object, analytical determination of the current range of the object and recording these range values. The series of probes with recording of time values is divided into two groups. For the first group of probes, linear interpolation of recorded range values is carried out, from the results of which the trajectory of the object is pre-determined. Depending on the determined speed value, a reference time interval is formed, at the end of which the second group of probes is carried out. A revised trajectory is determined from range and time instant values recorded in both groups of probes. When recording probe results and after determining the revised trajectory of the object, measurements of the range of the object, results of which differ from the previous reliable measurement value exceeding the limit error of range measurement, are cancelled. The revised trajectory of the object is re-determined from the remaining results which have been ruled reliable.

EFFECT: invention saves resources and increases service life of the device, and also reduces power consumption by cutting on the number of measurements in the series of probes with minimal error of determining speed of an object in a wide range of speed.

6 cl, 1 dwg

Description

The present invention relates to measuring technique and can be used to determine the range and speed or only the speed of a remote object, in particular for detecting and fixing violations of traffic rules by a vehicle.

A known method for determining the range and / or speed of a distant object [1], including repeated sensing of the object by periodically sending a series of n laser pulses to it and determining in each i-th sounding the time interval t _i between the moments of emission of the laser pulse and reception of the radiation reflected by the object, determining and registering at each sounding the values of the moments of the current time T _i at which the laser pulses are sent and the measured intervals and t _i in a series of n soundings, and determining The speed of the object V by determining the distances to the object with each sounding R _i = с · t _i / 2, where с is the speed of light, and linear interpolation of the values of R _i , for example, by the formula:

.

.

.According to the described method, the distance to the object is determined by the formula:

.

The specified procedure does not provide the minimum standard error of determining the speed and range. In addition, the synchronization of determining the range and speed of the object is not ensured.

The closest in technical essence to the proposed method is a method for determining the range and / or speed of a distant object, according to which the object is repeatedly probed by periodically sending a series of n laser pulses to it, in each i-th probe, the delay t _i between the moments of laser pulse emission is determined and receiving the radiation reflected by the object, and determine the current range to the object according to the formula R _i = ct _i / 2, where c is the speed of light; in this case, soundings are performed at a constant frequency without pauses, and the sounding results are divided into two equal groups: in the first group, the average distance value is determined

,

,

in the second group determine the average value of the range

and determine the speed of the object V according to the formula V = (R ₂ -R ₁ ) / T _1/2 , where T _1/2 is the time period between the first and second groups of the sensing series.

According to the described method, to increase the reliability of measurements, the results of measurements of R _i are compared with each other and, if any result differs from the previous one by more than 10 m, then the measurement is considered invalid, the results are canceled and the measurement is started again. As indicated in [2], if the object (car) exceeds the permissible speed, a third group of n / 2 soundings is added to a series of measurements of n = 800 soundings, and the average range value is determined from them

and re-determine the speed of the object by the formula V '= (R ₃ -R ₂ ) / T _2/3 , where T _2/3 is the time period between the second and third groups of the sensing series. The values of V and V 'are compared and, if they coincide with a given accuracy, the result obtained is displayed.

This method does not provide a minimum number of soundings per measurement, which leads to an unjustified decrease in the service life of the range meter and the speed and resource of the battery. In addition, the known method does not provide the minimum standard error of determining the speed and range with a minimum number of soundings in the series, especially when the object exceeds the permissible speed, and does not provide an unambiguous time reference of the range measurement result to a certain moment of the current time. This method also does not provide the possibility of taking measurements in one series in the presence of false measurements.

The objective of the invention is to save the resource and increase the service life of the equipment that implements the method, as well as reducing energy consumption when powering the equipment from an autonomous source, by reducing the number of measurements in a series of soundings with a minimum error in determining the speed of an object in a wide speed range. The objective of the invention is also to determine the distance to the object with a unique time reference. In addition, the object of the invention is the provision of the possibility of measuring range and / or speed in one series in the presence of false measurements.

This problem is solved due to the fact that in the known method for determining the range and / or speed of a distant object, including multiple sensing of the object by sending a series of n laser pulses to it, determining in each i-th probe the delay t _i between the moments of laser pulse emission and reception radiation reflected by the object, to determine the current distance to the object by the formula R _i = ct _i / 2, where c - velocity of light, and the registration of these distance values, wherein a series of probes is divided into two groups, register values Ia time T _i, at the instants i-th sensing a first group of probes produce n ₁ ≤n / 2 sounding is carried out a linear interpolation for the points in time T _i values of distance to the object R _i, for which the results of pre-determined object trajectory R * (t) in the form R * (t) = R ₀ * + V * t, where R ₀ * is the estimate of the distance to the object at time T ₁ corresponding to the first sounding, V * is the estimate of the speed of the object, t is the current time, counted from the moment of the first sounding, depending on a certain value of the velocity V * they base the basic time interval T _b , at the end of which a second group of soundings is performed in the amount of n ₂ = nn ₁ , after which the updated object path R ** (t) is determined from the values of the range R _i and time moments T _i R ** (t) = R ₀ ** + V ** t, where R ₀ ** is the updated estimate of the distance to the object at the time corresponding to the first sounding, V ** is the updated estimate of the speed of the object, t is the current time counted from the moment of the first sounding.

To improve accuracy, it is possible to cancel the measurements of the range to the object R _i during the recording of the results of soundings, the results of which differ from the value of the previously recognized reliable measurement R _il by an amount exceeding the marginal error of measuring the distance to the object.

After determining the refined trajectory of the object, it is advisable to cancel the measurements of the distance to the object R _i , the results of which differ from the refined estimate at the i-th time moment R ** (T _i ) by an amount exceeding the marginal error of measuring the range, after which the refined assessment of the trajectory of the object is re-determined according to the remaining recognized reliable sounding results.

Preliminary and final estimates of the distance to the object R ₀ at the initial moment of measuring T ₁ and the speed of the object V can be formed by the formulas:

Where

R ₀ - assessment of the distance to the object at time T ₁ ;

V is an estimate of the speed of the object;

R _im = c · t _i / 2 - recognized as a reliable result of measuring the distance to the object in the i-th sounding;

T _i - time points at which the measured range R _i

c is the speed of light

m is the number of recognized range measurements in a series of n soundings.

t _i is the delay between the moments of radiation of the laser pulse and the reception of the radiation reflected by the object in the i-th sounding.

The value of the base interval can be set depending on a preliminary estimate of the speed of the object by comparing a preliminary estimate of the speed of the object with a given value of speed and deciding on the choice of the base interval according to a predetermined rule.

You can choose a base interval, for example, so that if the preliminary estimate of the object’s speed exceeds the maximum permissible value, then the maximum possible value of the base interval T _{b is set} , and if it does not exceed, then the value of the base interval is set from 1.5 to 4 times less than the maximum possible .

The distance to the object R ** (T) at an arbitrary point in time T can be determined by the formula R ** (T) = R ₀ ** + V ** T, where R ₀ ** is an updated estimate of the range at the time of the first sounding, and V ** is an updated estimate of the velocity, and the time T is counted from the moment of the first sounding.

The drawing shows a timing diagram illustrating the described method.

Starting from time T ₁ , a group of n ₁ soundings is made, moments T _i are recorded, measured values of the range R ₁ ... R _{n1 are} determined and recorded, a preliminary assessment of the object’s path is made by linear interpolation of the measured distances, from which preliminary estimates of the velocity V * and range R ₀ *, for example, according to the above formulas or according to one of the known simplified procedures.

If the object’s speed determined in this way does not exceed the permissible value, then choose the measurement base T _b1 , if it exceeds, then select the increased value of the base T _b2 , form the corresponding time interval T _b and, after it, produce a second group of soundings, again registering the measured values of the range R _{n1 + 1} ... R _n . The ratio T _b2 / T _b1 can be selected in the range from 1.5 (a smaller value of this ratio has little effect on the final result) to 4 (with a higher value, the requirements for accuracy and measurement time are not met).

In the process of measurement exclude measurements that differ from the previous value by more than the maximum measurement error - such measurements are considered unreliable. At the end of a series of soundings based on the remaining m range measurements, which are recognized as reliable, a linear interpolation of the object’s trajectory is performed, for example, according to formulas (1) and (2), which implements the minimum mean square method that provides the smallest error in determining the speed and range. At the same time, accurate estimates of the velocity V ** and range at the initial instant of time R ₀ ** are formed. After that, check the available sensing results R _i for compliance with the condition | R ** (T _i ) -R _i | ≤ΔR, where ΔR is the maximum measurement error. Results R _i that do not meet this condition are canceled and, based on the remaining m sensing results, the estimates of the velocity V ** and range at the initial instant of time R ₀ ** are re-refined. The initial moment of time T ₁ corresponds to the moment of the first sounding, regardless of the number and sequence of canceled range measurements.

The range R ** (T) to the object at an arbitrary time instant T is determined by the formula R ** (T) = R ₀ ** + V ** T, which allows you to uniquely associate a range measurement to a specific point in time, for example, time for the end of a series of soundings.

Example 1

According to the proposed method, in the first and second groups, n ₁ = n ₂ = 200 soundings are performed with a repetition rate of F = 2220 1 / s. The total time of measuring the speed T _{ISM is} assumed to be 0.36 s. The measurement base T _b = T _ISM -n ₁ / F = 0.36-200 / 2220 ~ 0.27 s.

Under these conditions, the standard error of the velocity measurement using the simplest averaging algorithm adopted in [2],

σ _V = 2σ ₁ / T _b √n ₁ = 2σ ₁ / 0.27√200,

where σ ₁ is the standard error of the range measurement in one measurement.

When measured by the method [2] at the same measurement time, T _ISM = 0.36 s is required for n ₁₀ = n ₂₀ = 400 measurements, and the measurement base is T _b0 = T _ISM / 2 = 0.18 s. In this case, the standard error of the velocity measurement

σ _V0 = 2σ ₁ / T _b0 √n ₁₀ = 2σ ₁ / 0.18√400.

The ratio of these errors is σ _V / σ _V0 = (0.18√400) / (0.27√200) = 0.94. This means that with equal measurement time, the proposed method is practically inferior in accuracy to the prototype, and when using the optimal speed calculation algorithm (2), it surpasses it in accuracy. By the number of soundings per measurement, the gain of the proposed method is two times.

Example 2

In case of exceeding a certain predetermined speed limit of the object according to the known method, an additional series of soundings is performed for a duration of 0.18 s and a second speed estimate is made on a measuring base of 0.18 s. As a result, the total number of soundings is n ₀ = 3 n ₁₀ = 1200, and at the same time, the measurement error is reduced by √2 times, i.e. for the conditions of Example 1, the standard error of the velocity measurement will be

σ _V0 = 2σ ₁ (√2T _S0 √n ₁₀₎ 2 = _σ1 / 0,18√400 = 0,393σ _1.

With the same total number of soundings n = 1200 and the same measurement time T _ISM = 3n / F = 1200/2220 = 0.54 s, the measurement procedure according to the proposed method

provides speed measurement error [3]

.

.

The advantage of the proposed method for accuracy is 0.393 / 0.093 = 4.2 times.

The present invention provides a significant resource saving and increasing the service life of the equipment implementing the method, as well as reducing power consumption when powering the equipment from an autonomous source, by reducing the number of measurements in a series of soundings with a minimum error in determining the speed of an object in a wide speed range. In particular, the method allows:

- with the same number of soundings, significantly reduce the root-mean-square error of measuring speed and range, reducing it to the theoretically minimum possible value;

- significantly reduce the number of soundings necessary to ensure a given accuracy;

- reduce the time required for measurements with a given accuracy;

- unequivocally link the result of measuring the distance in time to any given moment, for example, the beginning, middle or end of a series of soundings, which is important, for example, for recording results.

Information sources

1. J. G. Dunne "Laser-based measuring device". US Patent 5,359,404, Oct. 25, 1994.

2. Yu.V. Abazadze, N. A. Litsarev, V. L. Pochtarev and others. "Features of the construction of a laser speed and range meter LISD-2M." Quantum Electronics, 2002, Volume 32, No. 3, S.247-250 - prototype.

3. B. R. Levin "Theoretical foundations of statistical radio engineering." Ed. “Radio and communications”, Moscow, 1975, v.2, p.131-139.

Claims (6)

1. A method for determining the range and / or speed of a distant object, including multiple sensing of the object by sending a series of n laser pulses to it, determining in each i-th sounding the delay t _i between the moments of radiation of the laser pulse and receiving the radiation reflected by the object, determining the current range to object of the formula R _i = _i ct / 2, where c - velocity of light, and the registration of these distance values, wherein a series of probes is divided into two groups, characterized in that the recorded time value T _i, at the instants i-th probe tion, in the first group of probes produce n ₁ ≤n / 2 sounding is carried out a linear interpolation for the points in time T _i, the range to the object values R _i, the results of which pre-defined trajectory R * (t) of the object in the form R * (t ) = R ₀ * + V * t, where R ₀ * is the estimate of the distance to the object at time T ₁ corresponding to the first sounding, V * is the estimate of the speed of the object, t is the current time counted from the moment of the first sounding, depending on a certain value of speed V * form the base time interval and T _b , at the end of which the second group of soundings is performed in the amount of n ₂ = nn ₁ , after which, based on the values of the range R _i and the time moments T _i recorded in both groups of soundings, the refined path of the object R ** (t) is determined in the form R ** (t) = R ₀ ** + V ** t, where R ₀ ** is a refined estimate of the distance to the object at a time corresponding to the first sounding, V ** is a refined estimate of the speed of the object, with preliminary and final parameters the interpolating path R ₀ and V are determined so that the standard deviation values of R _i , from the interpolating dependence was minimal, for example, formed by the formulas

,

,
where R _im = c · t / 2 - recognized as a reliable result of measuring the distance to the object in the i-th sounding;
m is the number of recognized range measurements in a series of n soundings. 2. The method according to claim 1, characterized in that in the process of recording the results of soundings, the measurements of the distance to the object R _{i are} canceled, the results of which differ from the value of the previously recognized reliable measurement R _i-1 by an amount exceeding the marginal error of measuring the distance to the object. 3. The method according to claim 1, characterized in that after determining the refined path of the object, the distance measurements to the object R _{i are} canceled, the results of which differ from the refined estimate at the i-th time moment R ** (T _i ) by an amount exceeding the marginal error range measurements, after which they re-define an updated estimate of the object’s trajectory based on the remaining recognized reliable sounding results. 4. The method according to claim 1, characterized in that the value of the base interval T _{b is} set depending on a preliminary estimate of the speed of the object by comparing a preliminary estimate of the speed of the object with a given value of speed and deciding on the choice of the base interval according to a predetermined rule. 5. The method according to claim 4, characterized in that if the preliminary estimate of the speed of the object exceeds the maximum permissible value, then set the maximum possible value of the base interval T _b , and if it does not exceed, then set the value of the base interval from 1.5 to 4 times less as much as possible. 6. The method according to claim 1, characterized in that the distance to the object R ** (T) at an arbitrary point in time T is determined by the formula R ** (T) = R ₀ ** + V ** T, and the time T counted from the moment of the first sounding.

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