RU2190238C1 - Radar device for prevention of motor vehicle collisions - Google Patents

Abstract

FIELD: radiolocation, applicable in systems designed for prevention of collisions of transport facilities, systems for upkeep of distance in a traffic flow. SUBSTANCE: the device has transmitting antenna 1, attenuator 2, transmitter 3, control signal conditioner 4, speed transducer 5, road condition transducer 6, receiver 7, receiving antenna 8, warning signal generation unit 9, detector 10, modulating code generator 11 radio- frequency oscillator 12, phase manipulator 13, power amplifier 14, local oscillator 15, first (16) and second (28) mixers, first (17) and second (29) intermediate-frequency amplifiers, correlator 18, controlled delay unit 19, first (20) and second (32) multiplexers, low-pass filter 21, extreme regulator 22, measuring instrument 23, first (24) and second (33) narrow-band filters, phase meter 25, actuating unit 26, first (27) and second (30) 90 deg. phase shifters, adder 31, amplitude detector 34 and gate 35. EFFECT: enhanced noise immunity and accuracy of measurement of distance to the advancing transport facilities by suppression of false signals (interference) received over the additional channels. 2 dwg

Description

 The invention relates to radar and can be used in systems for preventing collisions of vehicles, systems for maintaining distance in the traffic stream.

 Known radar devices for preventing collisions of cars (ed. St. USSR 457054, G 01 S 9/68, 1975; 794575, G 01 S 15/08, 1976; 915035, G 01 S 13/93, 1980; 926611, G 01 S 13/93, 1980; RF patent 2169929, G 01 S 13/93, 2000; US patents 3841427, G 01 S 13/93, 1976; 3898652, G 01 S 13/93, 1976 and others).

 Of the known devices, the closest to the proposed one is the "Radar device for preventing collisions with a car" (RF patent 2169929, G 01 S 13/93, 2000), which is selected as the base object.

 This device reduces the total radiation level of the sensors during their mass use, which reduces the influence of the microwave field on people, reduces the mutual influence of the sensors on each other, which reduces the likelihood of false alarms, improves accuracy characteristics, and also reduces the effect of radiation on other microwave devices.

However, in the specified device, the same value of the intermediate frequency can be obtained by receiving the signal reflected from the vehicle in front at the two frequencies ω _c and ω _s , i.e.:
ω _ol = ω _c -ω _g and ω _ol = ω _g -ω _s .
Therefore, if the tuning frequency ω _c taken as the main receiving channel, along with it will be a mirror receiving channel frequency ω _of which differs from the frequency ω _c on the 2ω _straight and located symmetrically (mirror) relative to the local oscillator frequency ω _r (FIG. 2). The conversion on the mirror channel of the reception occurs with the same conversion coefficient to _pr , as on the main channel. Therefore, it most significantly affects the selectivity and noise immunity of the device.

In addition to the mirror, there are other additional (combinational) reception channels. The most harmful combinational reception channels are those generated by the interaction of the first harmonic of the signal with the harmonics of the local oscillator of the small order (second, third, etc.), because The sensitivity of the device on these channels is close to the sensitivity of the main channel. So, under certain conditions, the frequencies correspond to two combinational channels:
ω _k1 = 2ω _g -ω _pr and ω _k2 = 2ω _g + ω _pr
where 2ω _g is the second harmonic of the local oscillator frequency.

 The presence of false signals (interference) received through the mirror and Raman channels leads to a decrease in noise immunity and accuracy of measuring the distance to the vehicle in front.

 An object of the invention is to increase the noise immunity and accuracy of measuring the distance to the vehicle in front by suppressing false signals (interference) received via additional channels.

The problem is solved in that in a radar device for preventing collisions with a vehicle, comprising a road condition sensor, a driver of a control signal, a second input of which is connected to an output of a speed sensor, an attenuator and a transmitting antenna, a high-frequency generator, a phase manipulator, and a second input which is connected to the output of the modulating code generator, and a power amplifier, the output of which is connected to the second input of the attenuator, of the A newly included receiving antenna, a first mixer, the second input of which is connected to the first output of the local oscillator, and a first intermediate frequency amplifier connected in series to the output of the speed sensor, a warning signal generating unit, the second input of which is connected to the output of the road condition sensor, and a recorder connected in series to the first output of the adjustable delay unit, the first multiplier, the second input of which is connected to the output of the power amplifier, a low-pass filter and a measuring device, The first narrow-band filter, the phase meter, the second input of which is connected to the first output of the local oscillator, and the executive unit, the first input of the adjustable delay unit through the extreme regulator are connected to the output of the low-pass filter, are connected to the output of the first multiplier, and a second mixer, a second intermediate-frequency amplifier, are introduced phase shifter 90 ^o, the second multiplier, a second narrowband filter, the amplitude detector, an adder and a key, wherein a second output of the local oscillator are connected in series a first phase aschatel 90 ^o, a second mixer, a second input coupled to an output of the receiving antenna, a second intermediate-frequency amplifier, a second phase shifter 90 ^o, an adder, a second input coupled to an output of the first intermediate frequency amplifier, a second multiplier, a second input coupled to an output the first intermediate frequency amplifier, the second multiplier, the second input of which is connected to the output of the receiving antenna, the second narrow-band filter, the amplitude detector and the key, the second input of which is connected to the output of the adder And an output connected to a second input of the adjustable delay unit.

 The structural diagram of the proposed device is presented in figure 1. Frequency diagrams explaining the process of forming additional receiving channels are shown in FIG. 2.

 The device comprises a transmitter 3, a receiver 7 and a correlator 18.

A phase manipulator 13 is connected to the output of the high-frequency generator 12, the second input of which is connected to the output of the modulating code generator 11, a power amplifier 14, an attenuator 2, and a transmitting antenna 1. A control signal driver 4 is connected to the output of the road condition sensor 6, the second input of which is connected with the output of the speed sensor 5, and the output is connected to the second input of the attenuator 2. The first mixer 16 is connected in series to the output of the receiving antenna 8, the second input of which is connected to the first output of the local oscillator 15, the first intermediate frequency amplifier 17, the adder 31, the second multiplier 32, the second input of which is connected to the output of the receiving antenna 8, the second narrow-band filter 33, the amplitude detector 34, key 35, the second input of which is connected to the output of the adder 31, adjustable delay unit 19 , the first multiplier 20, the second input of which is connected to the output of the power amplifier 14, the first narrow-band filter 24, the phase meter 25, the second input of which is connected to the output of the local oscillator 15, the warning signal generation unit 9, the second input of which is connected to the output m of a speed sensor 5, and the third input is connected to the output of the road condition sensor 6, and a recorder 10. To the second output of the local oscillator 15, a first 90 ^° phase shifter 27, a second mixer 28, the second input of which is connected to the output of the receiving antenna 8, are connected to the second amplifier 29, the intermediate frequency phase shifter 30 and second 90 ^o, the output of which is connected to the second input of the adder 31. to the output of the first multiplier 20 connected in series with a filter 21, a lowpass extreme regulator 22 and variable delay unit 19, the second you od which is connected to a fourth input of block 9 generate a warning signal. A measuring device 23 is connected to the output of the low-pass filter 21. An executive unit 26 is connected to the second output of the warning signal generating unit 9. In this case, the modulating code generator 11, the high-frequency generator 12, the phase manipulator 13 and the power amplifier 14 form a transmitter 3. The local oscillator 15, mixers 16 and 28, phase shifters 27, 30, intermediate frequency amplifiers 17, 29, adder 31, multiplier 32, narrow-band filter 33, amplitude detector 34 and key 35 form a universal frequency converter. The adjustable delay unit 19, the multiplier 20, and the low-pass filter 21 form a correlator 18.

The device operates as follows:
Sensor 5 determines the vehicle’s own speed and generates a signal proportional to the measured speed. The sensor 6 measures the coefficient of adhesion φ, depending on the state of the road. Shaper 4 generates voltage
U = f (V, φ),
where V is the vehicle speed.

Thus, so that the radiated power, depending on the speed of movement and the coefficient of adhesion, varies proportionally to V ⁴ / φ ² . The voltage acts on the controlled attenuator 2, which is a "pin" - a diode installed in the waveguide and changing its conductivity depending on V, i.e. transmitted power.

High frequency voltage
U ₁ (t) = V ₁ cos (ω _c t + φ _c ); 0≤t≤T _c
output from the generator 12 is supplied to a first input of the manipulator 13, the second input of which is supplied to the modulating code M (t) output from the generator 11. The output of the phase manipulator 13 generated phase-shift keyed (F _mn) is the signal
U ₂ (t) = V ₂ cos (ω _c t + φ _k (t) + φ _c ); 0≤t≤T _s ,
where φ _к (t) = {0, π} is the manipulated component of the phase that displays the law of phase manipulation in accordance with the modulating code M (t), and φ _к (t) = const for kτ _e <t <(k + 1) τ _e and can change abruptly at t = kτ _e , i.e. at the borders between elementary premises (k = 1,2, ..., N-1);
τ _e N - the duration and number of chips that make up the signal duration
T _c (T _c = Nτ _e ),
which is fed to the input of the power amplifier 14. The output of the latter is formed f _mn signal
U _c (t) = V _c cos (ω _c t + φ _к (t) + φ _c ); 0≤t≤T _c ,
which, having passed the attenuator 2, is radiated by the transmitting antenna 1 in the direction of the vehicle in front.

Это напряжение подается на второй вход сумматора 31, на выходе которого образуется суммарное напряжение
U_Σ1(t) = V_Σ1cos[ω_пр(t-τ₀)+φ_к(t-τ₀)+φ_пр], 0≤t≤Т_с,
где V_Σ1 = 2V_пр.Reflected from the vehicle in front is the signal F _mn
U ₀ (t) = V ₀ cos (ω (t-τ ₀ ) + φ _к (t-τ ₀ ) + φ ₀ ); 0≤t≤T _s ,
where τ ₀ = 2R / C is the delay of the reflected signal;
R is the distance between your own and the vehicles in front;
C is the speed of light propagation,
comes from the output of the receiving antenna 8 to the first inputs of the mixers 16 and 28, to the second inputs of which the voltage of the local oscillator 15 is applied:
U _g1 (t) = V _g cos (ω _g t + φ _g );
U _g2 (t) = V _g cos (ω _g t + φ _g +90 ^° ).
At the outputs of the mixers 16 and 28, voltages of combined frequencies are generated. Amplifiers 17 and 29 are allocated voltage intermediate (differential) frequency:
U _pr1 (t) = V _pr cos [ω _pr (t-τ ₀ ) + φ _to (t-τ ₀ ) + φ _pr ]
U _pr2 (t) = V _pr cos [ω _pr (t-τ ₀ ) + φ _to (t-τ ₀ ) + φ _pr -90 ^° ], 0≤t≤T _s ,
where U _CR = 1 / 2k ₁ V ₀ V _g ;
k ₁ - transfer coefficient of the mixers;
ω _CR = ω _c -ω _g is the intermediate frequency;
φ _ol = φ ₀ -φ _g .
The voltage U _p1 (t) is supplied to the first input of the adder 31. The voltage U _p2 (t) is supplied to the input of the phase shifter 30 by 90 ^° , at the output of which the following voltage is generated

This voltage is supplied to the second input of the adder 31, the output of which is formed by the total voltage
U _Σ1 (t) = V _Σ1 cos [ω _pr (t-τ ₀ ) + φ _к (t-τ ₀ ) + φ _pr ], 0≤t≤T _s ,
where V _Σ1 = 2V _ave .

This voltage is supplied to the second input of the multiplier 32, the first input of which receives reflected from the front of the vehicle in advance F _mn signal U ₀ (t). A harmonic voltage is generated at the output of the multiplier
U ₃ (t) = V ₃ cos (ω _g t + φ _g ), 0≤t≤T _s ,
where U ₃ = 1 / 2k ₂ V ₀ V _Σ1 ;
k ₂ - transfer coefficient of the multiplier.

Since the tuning frequency ω _{n =} narrow-band filter 33 is chosen equal to the local oscillator frequency ω _g (ω _n = ω _g ), the inharmonious voltage U ₃ (t) is emitted by the narrow-band filter 33 detected by the amplitude detector 34 and is supplied to the control input of the key 35, opening his. In the initial state, the key 35 is always closed.

The voltage U _Σ1 (t) from the output of the adder 31 through the public key 35 is supplied to the first input of the adjustable delay unit 19, which, together with the multiplier 20, the second input of which receives the F _mn signal U _c (t) from the output of the power amplifier 14, and the low-pass filter 21 forms a correlator 18. The correlation function R (τ) obtained at the output of the correlator 18 has a maximum at the value of the introduced adjustable delay τ ₀ . The correlation function R (τ ₀ ) is recorded by the measuring device 23. The maximum value of R (τ ₀ ) is maintained using the extreme controller 22 acting on the adjustable delay unit 19. When compensating for the time delay τ ₀ using the block 19 adjustable delay to the first input of the multiplier receives F _mn signal of intermediate frequency.

U _Σ2 (t) = V _Σ1 cos [ω _pr t + φ _k (t) + φ _pr ], 0≤t≤T _s .

и поступает на первый вход фазометра 25, на второй вход которого подается напряжение U_г(t) гетеродина 15. Фазометр 25 измеряет фазовый сдвиг Δφ, по которому точно определяется расстояние R_т до впереди идущего транспортного средства. Так формируется фазовая шкала измерения, которая является точной, но неоднозначной. Измененный фазовый сдвиг поступает в блок 9 выработки сигнала предупреждения.The output of the multiplier 20 produces a harmonic voltage
U ₄ (t) = V ₄ cos [ω _g t + φ _g (t) + Δφ], 0≤t≤T _s ,
where U ₄ = 1 / 2k ₂ V _c V _Σ1 ;
Δφ = φ _c -φ ₀ = ω _c 2R / C,
which is allocated by a narrow-band filter 24 tuned to the local oscillator frequency

and enters the first input of the phase meter 25, the second input of which is supplied with the voltage U _g (t) of the local oscillator 15. The phase meter 25 measures the phase shift Δφ, which accurately determines the distance R _t to the vehicle in front. This forms the phase scale of the measurement, which is accurate, but ambiguous. The changed phase shift enters the block 9 generate a warning signal.

The time shift τ ₀ is determined by the scale of the adjustable delay unit 19, from the second output of which it also enters the warning signal generation unit 9. Thus, a time scale for measuring the range R _gp to the vehicle in front is formed, which is rough, but unambiguous. Thus, the distance to the vehicle in front is measured accurately and unambiguously.

It should be noted that the phase scale, which allows measuring the distance to the vehicle in front with high accuracy, is ambiguous, i.e. a phase meter 25 measures the phase difference only modulo 2π:
ΔΦ = k + Δφ,
where k is the integer number of periods of the total phase difference (in phase cycles);
Δφ is the phase difference measured by the phase scale (measured in fractions of a single cycle, 0≤Δφ≤π).

To determine the integer number of periods of the total phase difference k, the time scale of measurements is used. The condition for matching the phase and time scales is that the doubled maximum error of measuring the distance R _gp on the rough (time) scale is less than the interval of unambiguous measurement of R _t on the exact (phase) scale.

2δ _Rgr <ΔR _one
δ _Rgr = (C / R _gr ) δ _τ : δ $\genfrac{}{}{0ex}{}{\text{2}}{\text{τ}}$ = (τ _e / 2q $\genfrac{}{}{0ex}{}{\text{2}}{\text{in}}$ ) (ΔF / Δf _c ),
where q _I ² - the signal-to-noise power ratio at the input of the receiver;
ΔF is the width of the output strip of the system for measuring the time delay of the reflected F _mn signal with respect to the probing one;
Δf _c is the bandwidth of the linear system, consistent with the spectrum of the used f _mn signal.

где m - некоторый коэффициент, связанный с Р_над следующим соотношением: m = Ф^-1(Р_над);
Ф^-1( ) - обратная функция интеграла вероятности;
Р_над - вероятность надежности согласования шкал (например, при Р_над= 0,9973 m=3).Given that τ _e = 1 / Δf _c , it is possible to replace the condition for matching the phase and time scales in the form

where m is a coefficient associated with P _{over the} following relationship: m = Ф ^-1 (P _over );
F ^-1 () is the inverse function of the probability integral;
P _over - the probability of reliability of the matching scales (for example, when P _over = 0,9973 m = 3).

From the above expression it follows that the reliability of matching the measuring scales does not depend on the distance R between the vehicles, but is determined by the characteristics of the complex F _mn signal and its energy, as well as the output frequency band of the measurement time scale.

Moreover, if R> R ₀ , where R ₀ is a safe distance, then a signal about the presence of a reserve of a safe distance is recorded in the recorder 10. If R <R ₀ , then the recorder 10 gives an alarm, for example, sound or light, and the executive unit 26, for example, the brake system of the car, automatically slows down the movement of your own vehicle with an intensity proportional to the deficit of the safe distance, as a result of which the distance to the front Transport increases to safe.

The operation of the device described above corresponds to the case of receiving the reflected useful f _mn signal from the vehicle in front through the main channel at a frequency ω _c (Fig. 2).

If a false signal (interference) is received on the mirror channel at a frequency ω _s :
U _s (t) = V _s cos [ω _s t + φ _s ], 0≤t≤T _s ,
then the amplifiers 17 and 29 of the intermediate frequency are allocated the following voltages:
_WP4 U (t) = V _WP4 cos [ω t + φ _{straight WP4]
Np5} U (t) = V _WP4 cos [ω t + φ _{straight WP4} +90 ^°], 0≤t≤T ₃
where V _CR4 = 1 / 2k ₁ V ₃ V _g1 ;
_straight ω = ω _r -ω _s - intermediate frequency.

0≤t≤T₃.The voltage U _p4 (t) from the output of the intermediate frequency amplifier 29 is supplied to the input of the phase shifter 30 by 90 ^° , at the output of which a voltage is generated:

0≤t≤T ₃ .

The _voltages U _p4 (t) and U _p6 (t) supplied to the two inputs of the adder 31 are compensated at its output.

Therefore, a false signal (interference) received on the mirror channel at a frequency ω _s is suppressed.

For a similar reason, a false signal (interference) received on the first combination channel at a frequency ω _{k1 is also} suppressed.
If a false signal (interference) is received on the second combination channel at a frequency ω _k2
U _к2 (t) = V _к2 cos [ω _к2 t + φ _к2 ], 0≤t≤T _к2 ,
then the amplifiers 17 and 29 of the intermediate frequency are allocated the following voltages:
_Pr7 U (t) = V _pr7 cos [ω t + φ _{straight pr7]
Pr8} U (t) = V _pr7 cos [ω t + φ _{straight pr7} -90 ^°], 0≤t≤T _k2
where V _pr7 = 1 / 2k ₁ V _k2 V _g3 ;
ω = ω _{ave k2} -2ω _g;
φ _pr7 = φ _k2 -φ _g .

0≤t≤T_к2.The voltage U _p8 (t) from the output of the intermediate frequency amplifier 29 is supplied to the input of the phase shifter 30 by 90 ^° , at the input of which a voltage is generated

0≤t≤T _k2 .

Voltages U _p7 (t) and U _p9 (t) are supplied to the two inputs of the adder 31, the output of which produces a voltage
_{U Σ3 (t) = V Σ3} cos [ω t + φ _{straight pr7],} 0≤t≤T _k2
where V _Σ3 = 2V _pr7 .

This voltage is multiplied in the multiplier 32 with the received false signal (interference) U _k2 (t).

As a result of multiplication, a harmonic voltage is formed
U ₅ (t) = V ₅ cos [2ω _g t + φ _g ], 0≤t≤T _k2 ,
where V ₅ = 1 / 2k ₂ V _к2 V _Σ3 ,
which does not fall into the passband of the narrow-band filter 33, the key 35 does not open and the false signal (interference) received on the second combinational channel at a frequency ω _k2 is suppressed.

 Thus, to suppress false signals (interference) received via the mirror and the first Raman channel, the phase-compensation method is used.

To suppress false signals (interference) received on the second combinational channel at a frequency ω _k2 , the method of narrow-band filtering is used.

 This device reduces the total radiation level of the sensors during their mass use, which reduces the influence of the microwave field on people, reduces the mutual influence of the sensors on each other, which reduces the likelihood of false alarms, improves accuracy characteristics, and also reduces the effect of radiation on other microwave devices.

 Using this device eliminates the main cause of road traffic accidents associated with non-compliance with the distance. By accurately measuring the distance to the vehicle in front, reserves are created to increase the density of traffic on roads; thereby increasing their throughput. The device promptly informs the driver about the speed of the car, the condition of the road and the distance to the vehicle in front, and also allows to simplify the process of driving a car in a tense situation on a busy highway, by freeing the driver from the function of evaluating and maintaining a safe distance to the vehicle in front.

Moreover, the measurement of the phase shift Δφ is carried out at a fixed frequency ω _{g of the} local oscillator. Therefore, the instability of the carrier frequency of the reflected F _mn signal, due to various destabilizing factors, does not affect the measurement results. In addition, this device allows you to realize the advantages inherent in complex F _mn signals, including increasing sensitivity with a low signal-to-noise ratio. This is achieved by convolution of the spectrum of a complex F _mn signal, which is converted into a narrow-band harmonic voltage, which allows you to select it with a narrow-band filter, filtering out a significant part of noise and interference, i.e., to increase the real sensitivity of the device with a low signal to noise ratio.

 Complex signals also have energy and structural secrecy and allow structural selection. This means that there is a new opportunity to isolate these signals operating in the same frequency band and at the same time intervals with other signals and interference.

 The proposed device in comparison with the base object provides increased noise immunity and accuracy of measuring the distance to the vehicle in front. This is achieved by suppressing false signals (interference) received via additional (mirror and Raman) channels.

Claims (1)

A radar device for preventing collisions with a vehicle, comprising a road condition sensor, a driver of a control signal, the second input of which is connected to the output of the speed sensor, an attenuator and a transmitting antenna, a series-connected high-frequency generator, a phase manipulator, the second input of which is connected to the output of the modulating code generator , and a power amplifier, the output of which is connected to the second input of the attenuator, the receiving antenna connected in series, the first a mixer, the second input of which is connected to the first output of the local oscillator, and the first intermediate frequency amplifier, a warning signal generating unit connected to the output of the speed sensor in series, the second input of which is connected to the output of the road condition sensor, and the recorder, connected in series to the first output of the adjustable delay unit a multiplier, the second input of which is connected to the output of the power amplifier, a low-pass filter and a measuring device, connected in series to the output of the first The multiplier is a first narrow-band filter, a phase meter, the second input of which is connected to the first output of the local oscillator, a warning signal generating unit, the fourth input of which is connected to the second output of the adjustable delay unit, and the executive unit, the first input of the adjustable delay unit through an extreme regulator is connected to the output of the low-pass filter characterized in that it entered the second mixer, the second intermediate-frequency amplifier, the two phase shifter 90 ^o, the second multiplier, a second narrowband filter Vp projectile loader detector, an adder and a key, wherein a second output of the local oscillator connected in series with the first phase shifter 90 ^o, a second mixer, a second input coupled to an output of the receiving antenna, a second intermediate-frequency amplifier, a second phase shifter 90 ^o, an adder, a second input coupled to the output of the first intermediate frequency amplifier, the second multiplier, the second input of which is connected to the output of the receiving antenna, the second narrow-band filter, the amplitude detector and the key, the second input of which is connected to the output torus, and the output is connected to the second input of the adjustable delay unit.

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