阅读说明：本技术 一种非接触式行驶车辆加速度测量方法 (Non-contact type running vehicle acceleration measuring method ) 是由 陈瑞 刘景顺 何辉 胡志勇 褚兆飞 于 2020-04-26 设计创作，主要内容包括：本发明公开了一种非接触式行驶车辆加速度测量方法,首先采用能够发射单频连续波和调频连续波的微波雷达,在T1时刻,先用单频连续波测量出目标的多普勒速度v<Sub>d</Sub>,然后利用调频连续波测量目标的距离D；根据微波雷达的安装高度H和距离D计算目标运动方向与微波雷达波束方向的夹角；步骤3、根据夹角θ计算T1时刻目标真正的速度v<Sub>1</Sub>；按照前述方法计算T2时刻目标真正的速度v<Sub>2</Sub>,根据T1时刻和T2时刻的速度计算加速度。本发明利用雷波雷达高精度的测量计算加速度,大大降低了加速度的测量成本,提高了测量精度,提高了环境适应能力,可以有效应对雨、雾、霾、强光照等环境因素均会对激光头产生影响。(The invention discloses a non-contact type acceleration measuring method for a running vehicle, which comprises the steps of firstly adopting a microwave radar capable of emitting single-frequency continuous waves and frequency-modulated continuous waves, and firstly measuring the Doppler velocity v of a target by using the single-frequency continuous waves at the time of T1 d Then, measuring the distance D of the target by using frequency modulation continuous waves; calculating an included angle between the target movement direction and the microwave radar wave beam direction according to the installation height H and the distance D of the microwave radar; step 3, calculating the real speed v of the target at the time of T1 according to the included angle theta 1 (ii) a The true speed v of the target at time T2 is calculated according to the method described above 2 Acceleration is calculated from the velocities at time T1 and time T2. The invention utilizes the high-precision measurement of the radar to calculate the acceleration which is largeThe acceleration measuring cost is greatly reduced, the measuring precision is improved, the environment adaptive capacity is improved, and the laser head can be effectively influenced by environmental factors such as rain, fog, haze and strong illumination.)

1. A non-contact running vehicle acceleration measuring method, characterized by comprising the steps of:

step 1, the invention adopts a microwave radar capable of transmitting single-frequency continuous waves and frequency-modulated continuous waves, and at the time of T1, the Doppler velocity v of a target is measured by the single-frequency continuous waves_dThen, measuring the distance D of the target by using frequency modulation continuous waves;

step 2, calculating the included angle between the target movement direction and the microwave radar wave beam direction according to the installation height H and the distance D of the microwave radar

Step 3, calculating the real speed of the target at the time of T1 according to the included angle theta,

step 4, calculating the real speed v of the target at the time T2 according to the method from the step 1 to the step 3₂，

Step 5, calculating the acceleration according to the speeds at the time T1 and the time T2

2. The noncontact traveling vehicle acceleration measurement method according to claim 1, characterized in that: the frequency modulation continuous wave for measuring the target distance D in the step 1 uses the triangular wave to sweep and measure the distance and the speed v of the target₀By the velocity v₀Correcting for Doppler velocity v_d。

3. The noncontact traveling vehicle acceleration measurement method according to claim 2, characterized in that: in the step 1, the distance and the speed v of the target are measured by utilizing the triangular wave frequency sweep₀The specific method comprises the following steps:

for stationary targets, radar transmission frequency f_tFrequency f received after reflection from the target_rThe difference is the frequency difference f_bThus, there is formula (1):

f_b＝f_t-f_rformula (1)

The radar sends out a signal, the back and forth of the target reflection is carried out, and the time is t_dSince there is formula (2), where D is the distance from the target to the radar, c is the speed of light:

frequency sweep bandwidth f of radar_devAnd sweep time t_sDelay time t_dDetermining the frequency difference f_bDue to the formula (3):

substituting the formula (2) into the formula (3), and substituting the formula (1) to obtain a formula (4):

for a moving target, when 1 triangular wave sweep is completed, 2 frequency differences can be obtained: up frequency difference F_buSum and fall frequency difference f_bdThe difference of rising frequency is determined by the distance frequency f of the target_bAnd Doppler frequency f_dDifference of difference, down-frequency difference from the range frequency f of the target_bAnd Doppler frequency f_dAnd, expressed as formula (5) and formula (6):

f_bu＝f_b-f_dformula (5)

f_bd＝f_b+f_dFormula (6)

Doppler frequency f_dCan be determined from the center frequency f₀Since the velocity v and the light velocity c are calculated, formula (7):

substituting the formula (5), the formula (6) and the formula (7) into the formula (4), and arranging to obtain the formula (8) and the formula (9):

4. a noncontact traveling vehicle acceleration measurement method according to claim 3, characterized in that: in the step 1, a data packet is transmitted at each moment, wherein the data packet comprises a frequency modulation continuous wave, and the frequency modulation continuous wave comprises a fixed frequency band, an ascending frequency band and a descending frequency band.

5. The noncontact traveling vehicle acceleration measurement method according to claim 4, characterized in that: the rising frequency segment and the falling frequency segment are equal in time.

Technical Field

The invention belongs to the technical field of radars, relates to an acceleration measuring method, and particularly relates to a non-contact type running vehicle acceleration measuring method.

Background

The existing non-contact acceleration measurement mainly depends on a laser technology, the distance is measured by laser, and the speed and the acceleration of a target are measured for multiple times in fixed time.

The existing laser measurement acceleration has the problems of high equipment cost and large measurement acceleration deviation, and has poor environment adaptability.

The reason why the laser technology is costly:

1. the laser device is high in manufacturing cost; 2. in order to measure the acceleration, 2 or more laser heads must be used for detection.

The laser technology measures the reason of inaccurate acceleration:

1. the laser is used for measuring the distance, the speed needs to be calculated through 2 or more lasers, and then the acceleration is calculated through the speed, so that the acceleration measurement is calculated for multiple times, and the accumulated error is large; 2. the measured target is irregular in shape, most of lasers are electro-optical or linear light, and laser is irradiated on the irregular target to generate deviation and cause measurement acceleration errors; 3. the number of laser devices is 2 or more, and the mounting position can not be ensured to be consistent with the ideal position in the actual mounting process, so that the error of acceleration measurement can be generated. The reason for the poor environmental adaptability of laser technology is: environmental factors such as rain, fog, haze, strong light all can produce the influence to the laser head, seriously probably leads to the laser instrument to damage.

The microwave radar can measure the speed and the distance of a target, the measurement accuracy is high, but the acceleration cannot be directly measured, so that the measurement cost is greatly reduced if the microwave radar can be used for calculating the acceleration of the target. The problem solved by the invention is to accurately measure the acceleration of a vehicle or other objects in a non-contact way. The non-contact accurate acceleration measurement is realized by utilizing the speed measurement and distance measurement technology of the microwave radar.

Disclosure of Invention

The invention aims to provide a new method for measuring acceleration by adopting a microwave radar, which solves the problems of high cost, poor precision and poor environment adaptability of non-contact acceleration measurement. The invention uses the microwave radar technology to realize the non-contact acceleration measurement with low cost, high precision and strong adaptability.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

a non-contact running vehicle acceleration measuring method, characterized by comprising the steps of:

step 1, the invention adopts a microwave radar capable of transmitting single-frequency continuous waves and frequency-modulated continuous waves, and at the time of T1, the Doppler velocity v of a target is measured by the single-frequency continuous waves_dThen, measuring the distance D of the target by using frequency modulation continuous waves;

step 2, calculating the included angle between the target movement direction and the microwave radar wave beam direction according to the installation height H and the distance D of the microwave radar

Step 3, calculating the real speed of the target at the time of T1 according to the included angle theta,

step 4, calculating the real speed v of the target at the time T2 according to the method from the step 1 to the step 3₂，

Step 5, calculating the acceleration according to the speeds at the time T1 and the time T2

Preferably, the frequency-modulated continuous wave for measuring the target distance D in step 1 uses a triangular wave frequency sweep to measure the distance and the speed v of the target₀By the velocity v₀Correcting for Doppler velocity v_dIn particular, when the velocity v measured by means of frequency-modulated continuous waves is used₀And velocity measured by a single-frequency continuous wavev_dIf the difference is within the threshold value range, the speed v is selected_dIf the calculated value is larger than the threshold range, the microwave radar is indicated to have faults or other interference factors, and detection equipment is needed.

Preferably, in step 1, the distance and the velocity v of the target are measured by using a triangular wave frequency sweep₀The specific method comprises the following steps:

for stationary targets, radar transmission frequency f_tFrequency f received after reflection from the target_rThe difference is the frequency difference f_bThus, there is formula (1):

f_b＝f_t-f_rformula (1)

The radar sends out a signal, the back and forth of the target reflection is carried out, and the time is t_dSince there is formula (2), where D is the distance from the target to the radar, c is the speed of light:

frequency sweep bandwidth f of radar_devAnd sweep time t_sDelay time t_dDetermining the frequency difference f_bDue to the formula (3):

substituting the formula (2) into the formula (3), and substituting the formula (1) to obtain a formula (4):

for a moving target, when 1 triangular wave sweep is completed, 2 frequency differences can be obtained: up frequency difference F_buSum and fall frequency difference f_bdThe difference of rising frequency is determined by the distance frequency f of the target_bAnd Doppler frequency f_dDifference of difference, down-frequency difference from the range frequency f of the target_bAnd Doppler frequency f_dAnd, expressed as formula (5) and formula (6):

f_bu＝f_b-f_dformula (5)

f_bd＝f_b+f_dFormula (6)

Doppler frequency f_dCan be determined from the center frequency f₀Since the velocity v and the light velocity c are calculated, formula (7):

substituting the formula (5), the formula (6) and the formula (7) into the formula (4), and arranging to obtain the formula (8) and the formula (9):

preferably, in step 1, a data packet is transmitted at each time, where the data packet includes a frequency modulated continuous wave, and the frequency modulated continuous wave includes a fixed frequency band, a rising frequency band, and a falling frequency band.

Preferably, the rising frequency segment and the falling frequency segment are equal in time.

The invention has the beneficial effects that:

the method comprises the steps of firstly measuring the speed value of the moving target by using the single-frequency continuous wave according to the Doppler principle, then measuring the speed and distance value of the target by using the frequency-modulated continuous wave, and then matching the speed value measured by using the single-frequency continuous wave with the speed value measured by using the frequency-modulated continuous wave, thereby obtaining the distance information and the accurate speed information of the target. By two measurements of the interval time Δ t, the acceleration value at a given distance is given: the method utilizes the high-precision measurement of the radar to calculate the acceleration, greatly reduces the measurement cost of the acceleration, improves the measurement precision, improves the environmental adaptability, and can effectively deal with the influence of environmental factors such as rain, fog, haze, strong illumination and the like on the laser head.

The frequency modulation signal generator of the device generates digital signals by a processor and converts the digital signals into analog signals by a DAC (digital-to-analog converter). Due to the characteristics of circuits and devices, the frequency nonlinear distortion of the generated frequency modulation continuous wave exists, and the frequency linearization of the frequency modulation continuous wave is realized by adopting digital predistortion correction in the device.

Drawings

Fig. 1 is a schematic structural diagram of a microwave radar used in the embodiment of the present invention.

Fig. 2 is a schematic diagram of a data packet signal transmitted by a microwave radar according to an embodiment of the present invention.

Fig. 3 is a schematic diagram of using a triangular wave frequency sweep as a microwave radar frequency modulated continuous wave in an embodiment of the present invention.

FIG. 4 is a diagram illustrating a Doppler frequency calculation method according to the present invention.

FIG. 5 is a schematic diagram of an algorithm for calculating a target acceleration according to the present invention.

Detailed Description

The embodiments of the present invention will be described in further detail with reference to the drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

The microwave radar adopted by the invention is schematically shown in fig. 1, wherein, LNA is a low noise amplifier, IF is an intermediate frequency signal, ADC is an analog-to-digital converter, PA is a power amplifier,is a mixer.

A noncontact running vehicle acceleration measurement method comprising the steps of:

step 1, the invention adopts a microwave radar capable of transmitting single-frequency continuous waves and frequency-modulated continuous waves, and at the time of T1, the Doppler velocity v of a target is measured by the single-frequency continuous waves_dThen, measuring the distance D of the target by using frequency modulation continuous waves;

step 2, calculating the included angle between the target movement direction and the microwave radar wave beam direction according to the installation height H and the distance D of the microwave radar

Step 3, calculating the real speed of the target at the time of T1 according to the included angle theta,

step 4, calculating the real speed v of the target at the time T2 according to the method from the step 1 to the step 3₂，

Step 5, calculating the acceleration according to the speeds at the time T1 and the time T2

The frequency modulation continuous wave for measuring the target distance D in the step 1 uses the triangular wave to sweep and measure the distance and the speed v of the target₀By the velocity v₀Correcting for Doppler velocity v_dIn particular, when the velocity v measured by means of frequency-modulated continuous waves is used₀And velocity v measured by a single-frequency continuous wave_dIf the difference is within the threshold value range, the speed v is selected_dIf the calculated value is larger than the threshold range, the microwave radar is indicated to have faults or other interference factors, and detection equipment is needed.

In the step 1, the distance and the speed v of the target are measured by utilizing the triangular wave frequency sweep₀The specific method comprises the following steps:

the transmitting channel of the microwave radar transmits one data packet (one frame) at each time, the data packet includes a frequency modulated continuous wave, and the frequency modulated continuous wave includes a fixed frequency segment t1, a rising frequency segment t2 and a falling frequency segment t3, in this embodiment, the time of the rising frequency segment and the time of the falling frequency segment are equal, i.e., t2 is t3, and the frequency waveform of the microwave signal transmitted by the transmitting channel is as shown in fig. 2. The frequency modulated continuous wave uses a triangular wave frequency sweep, and the modulation mode is shown in fig. 3, where ts is t2 in fig. 2 and t 3.

For stationary targets, radar transmission frequency f_tFrequency f received after reflection from the target_rThe difference is the frequency difference f_bThus, there is formula (1):

f_b＝f_t-f_rformula (1)

The radar sends out a signal, the back and forth of the target reflection is carried out, and the time is t_dSince there is formula (2), where D is the distance from the target to the radar, c is the speed of light:

frequency sweep bandwidth f of radar_devAnd sweep time t_sDelay time t_dDetermining the frequency difference f_bDue to the formula (3):

substituting the formula (2) into the formula (3), and substituting the formula (1) to obtain a formula (4):

as shown in fig. 4, for a moving target, when 1 triangular wave sweep is completed, 2 frequency differences can be obtained: up frequency difference F_buSum and fall frequency difference f_bdThe difference of rising frequency is determined by the distance frequency f of the target_bAnd Doppler frequency f_dDifference of difference, down-frequency difference from the range frequency f of the target_bAnd Doppler frequency f_dAnd, expressed as formula (5) and formula (6):

f_bu＝f_b-f_dformula (5)

f_bd＝f_b+f_dFormula (6)

Doppler frequency f_dCan be determined from the center frequency f₀Since the velocity v and the light velocity c are calculated, formula (7):

substituting the formula (5), the formula (6) and the formula (7) into the formula (4), and arranging to obtain the formula (8) and the formula (9):

wherein ts is t2 t 3.

The specific parameters of this example are as follows:

f1＝24.05GHz

f2＝24.25GHz

t1＝21ms

t2＝5ms

t3＝5ms

ADC sample rate 187500

The digital signal processing flow is as follows:

the device can measure the acceleration of the moving vehicle at a distance of 20-40 m, and can achieve the following indexes:

acceleration measurement range: (-10 to 10) m/S2;

acceleration measurement accuracy: is less than or equal to +/-0.2 m/S2.

The above embodiments are merely illustrative of the present invention and are not to be construed as limiting the invention. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that various combinations, modifications or equivalents may be made to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention, and the technical solution of the present invention is covered by the claims of the present invention.