Accurate multi-element ultrasonic radar detection method

Abstract

The invention discloses an accurate multi-element ultrasonic radar detection method, which comprises the steps of controlling an ultrasonic radar of a target vehicle to emit ultrasonic waves to an obstacle and receive reflected waves, and obtaining a unit signal period of the ultrasonic radar and an emission frequency change value in the unit signal period; determining a frequency function for transmitting ultrasonic waves, and determining a frequency function for reflecting the ultrasonic waves; an ultrasonic difference frequency expression is obtained according to the difference value of the frequency function of the transmitted ultrasonic waves and the frequency function of the reflected ultrasonic waves, and the distance between the target vehicle and the obstacle is calculated based on the peak frequency of the ultrasonic difference frequency and the ultrasonic difference frequency expression; according to the difference value of the frequency function of the transmitted ultrasonic waves and the frequency function of the reflected ultrasonic waves, an ultrasonic wave difference frequency expression in the frequency rising band and an ultrasonic wave difference frequency expression in the frequency falling band are obtained, and the speed of the obstacle is calculated. According to the method, on one hand, accurate distance measurement can be achieved, and on the other hand, the speed of the obstacle can be rapidly calculated.

Description

Technical Field

[0001] The present invention relates to the field of vehicle environment perception and detection technology, and in particular to an accurate multi-factor ultrasonic radar detection method. Background Art

[0002] Currently, the relevant reversing radar system is a mature ultrasonic radar route: it emits ultrasonic waves of a specific frequency and feedbacks the corresponding distance. The basic reversing radar system consists of 3-4 existing reversing radars, a reversing radar ECU, and a radar group consisting of multiple ultrasonic radars. By calculating the echo of the ultrasonic waves emitted by a certain probe itself (A transmits, A receives), or calculating the echoes emitted by other probes (B transmits, A receives), multiple sets of data are comprehensively used to determine the actual location of the obstacle. However, all current reversing radar system solutions have limited detection distances and a maximum detection distance. The detection range of ultrasonic radar is usually between 1 meter and 5 meters, and the specific distance depends on the radar's operating frequency, transmission power, receiving sensitivity, the reflective characteristics of the target object, and environmental factors. This limited detection distance restricts the application of ultrasonic radar in scenarios that require longer-distance detection.

[0003] Traditional, simple, single-transmitter, single-receiver ultrasonic radar solutions have limited detection range. Ultrasonic radars are primarily used for parking, providing accurate output of obstacle type and speed. Other high-end ultrasonic radars are inadequate and cannot fully capture obstacles. Three-chamber parking sensors are typically used in entry-level or low-priced vehicles or aftermarket parking sensors. They primarily identify obstacles by measuring the echo size of the ultrasonic sensor itself, but lack precise distance measurement. Four- or six-chamber parking sensors utilize multiple ultrasonic sensors. These sensors calculate the ultrasonic echo from a specific sensor (A transmits, A receives) or from other sensors (B transmits, A receives). These multiple data sets are combined to determine the true obstacle location. Consequently, multiple sets of measurement data are generated for each obstacle, providing a comprehensive estimate of the obstacle's true location. This solution offers high accuracy and is adopted by many international parking sensor vendors. However, this solution involves multiple ultrasonic sensors with different receiving methods, requiring a specific cycle for stable ranging. However, the combination of multiple ultrasonic sensors results in a lengthy ranging cycle, often increasing ranging latency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an accurate multi-factor ultrasonic radar detection method to address the shortcomings of the existing technology. On the one hand, the method provided by the present invention can accurately measure the distance, and on the other hand, it can break through the constraints of a single unchanging ultrasonic phase difference. By controlling the ultrasonic radar to measure the frequency and phase difference of the reflected wave, the speed of the obstacle can be quickly calculated, and the application requirements in various complex scenarios can be met.

[0005] To achieve the above object, according to one aspect of the present invention, there is provided a precise multi-element ultrasonic radar detection method, including:

[0006] Controlling the ultrasonic radar of the target vehicle to emit ultrasonic waves to a stationary obstacle and receive the reflected waves, and obtaining the unit signal period of the ultrasonic radar and the change value of the emission frequency within the unit signal period;

[0007] Determining the frequency function of the emitted ultrasonic waves and the frequency function of the reflected ultrasonic waves;

[0008] Obtaining an ultrasonic beat frequency expression based on the difference between the frequency function of the emitted ultrasonic waves and the frequency function of the reflected ultrasonic waves;

[0009] Calculating the distance between the target vehicle and the stationary obstacle based on the peak frequency of the ultrasonic beat frequency and the ultrasonic beat frequency expression.

[0010] In the above solution, the frequency function of the emitted ultrasonic waves is:

[0011]

[0012] where f t is the frequency of the emitted ultrasonic waves; f0 is the frequency of the emitted ultrasonic waves at time 0; t is the period time; T m is the unit signal period of the ultrasonic radar, that is, the minimum accuracy of time; 4Δf is the change value of the emission frequency within the unit signal period, where Δf is the minimum frequency change gradient.

[0013] In the above solution, the frequency function of the reflected ultrasonic waves is:

[0014]

[0015] where f r is the frequency of the reflected ultrasonic waves; f0 is the frequency of the emitted ultrasonic waves at time 0; t is the period time; T m is the unit signal period of the ultrasonic radar, that is, the minimum accuracy of time; 4Δf is the change value of the emission frequency within the unit signal period, where Δf is the minimum frequency change gradient; R is the distance between the target vehicle and the obstacle; c is the speed of sound.

[0016] In the above solution, the method for obtaining the ultrasonic beat frequency expression based on the difference between the frequency function of the emitted ultrasonic waves and the frequency function of the reflected ultrasonic waves is:

[0017]

[0018] where f b is the ultrasonic beat frequency.

[0019] In the above solution, the method for calculating the distance between the target vehicle and the stationary obstacle based on the peak frequency of the ultrasonic beat frequency and the ultrasonic beat frequency expression is as follows:

[0020] According to the ultrasonic beat frequency expression, it is obtained that:

[0021]

[0022] After the transmitted signal is scattered by the obstacle, a frequency difference, that is, a beat frequency signal, will be generated between the echo signal and the transmitted signal. The frequency f of the beat frequency signal b has a linear relationship with the distance R from the obstacle to the radar (target vehicle). Specifically, this relationship can usually be expressed as:

[0023] When the ultrasonic beat frequency is the peak frequency, for the convenience of calculation, the ultrasonic beat frequency expression can be transformed into:

[0024]

[0025] where f bav is the peak line value of f b , and f m is the frequency of the unit signal period T m .

[0026] According to another aspect of the present invention, an accurate multi-element ultrasonic radar detection method is provided, including:

[0027] In the above solution, control the ultrasonic radar of the target vehicle to emit ultrasonic waves to the moving obstacle and receive the reflected waves, and obtain the unit signal period of the ultrasonic radar and the change value of the emission frequency within the unit signal period;

[0028] Determine the frequency function of the transmitted ultrasonic wave and the frequency function of the reflected ultrasonic wave;

[0029] Obtain the ultrasonic beat frequency expression in the ascending frequency band and the ultrasonic beat frequency expression in the descending frequency band according to the difference between the frequency function of the transmitted ultrasonic wave and the frequency function of the reflected ultrasonic wave;

[0030] Calculate the speed of the moving obstacle based on the ultrasonic beat frequency expression in the ascending frequency band and the ultrasonic beat frequency expression in the descending frequency band.

[0031] In the above solution, the frequency function of the transmitted ultrasonic wave is:

[0032]

[0033] where f t is the frequency of the transmitted ultrasonic wave; f0 is the frequency of the transmitted ultrasonic wave at time 0; t is the period time; Tm is the unit signal period of the ultrasonic radar, i.e., the minimum precision of time; 4Δf is the change value of the emission frequency within the unit signal period, where Δf is the minimum frequency change gradient.

[0034] In the above solution, the frequency function of the reflected ultrasonic wave is:

[0035]

[0036] where, f r is the frequency of the reflected ultrasonic wave; f0 is the frequency of the emitted ultrasonic wave at time 0; f d is the median of the ultrasonic wave frequency, i.e., half of the sum of the maximum and minimum values of the ultrasonic wave frequency, used to distinguish the rising and falling trends of the ultrasonic wave; t is the cycle time; T m is the unit signal period of the ultrasonic radar, i.e., the minimum precision of time; 4Δf is the change value of the emission frequency within the unit signal period, where Δf is the minimum frequency change gradient; R is the distance between the target vehicle and the obstacle; c is the speed of sound.

[0037] In the above solution, the method for obtaining the ultrasonic wave difference frequency expression in the rising frequency band and the ultrasonic wave difference frequency expression in the falling frequency band based on the difference between the emission ultrasonic wave frequency function and the reflected ultrasonic wave frequency function is:

[0038] Rising frequency band:

[0039]

[0040] Falling frequency band:

[0041]

[0042] where; fx + is the ultrasonic wave difference frequency expression in the rising frequency band; f b- is the ultrasonic wave difference frequency expression in the falling frequency band.

[0043] In the above solution, the method for calculating the speed of the moving obstacle based on the ultrasonic wave difference frequency expression in the rising frequency band and the ultrasonic wave difference frequency expression in the falling frequency band is:

[0044] From the ultrasonic wave difference frequency expression in the rising frequency band and the ultrasonic wave difference frequency expression in the falling frequency band, it is obtained that:

[0045]

[0046] It is obtained that:

[0047]

[0048] Where v is the speed of the obstacle; λ is the wavelength of the ultrasonic wave; f tm It is the modulation frequency of the ultrasonic emission signal. The frequency of the emission signal will change from a certain starting frequency to another ending frequency within a cycle. This change process is affected by f tm Modulated, specifically, if the frequency of the ultrasonic emission signal changes linearly with time, then f tm This is the slope of the linear change, in other words, f tm Determines how fast the frequency of the ultrasonic signal changes.

[0049] In the above solution, the ultrasonic radar has normal ultrasonic radar functions. When the ultrasonic radar identifies an excessively weak radar echo, it does not shield it and still outputs a characteristic echo signal.

[0050] In the above solution, the ultrasonic radar transmission setting is:

[0051]

[0052] Among them, U t The instantaneous voltage of the ultrasonic emission signal can represent the amplitude; f0 is the frequency of the ultrasonic emission at time 0; t is the cycle time; f m is the frequency of the unit signal.

[0053] Theoretical basis of the present invention: The present invention provides a precise multi-factor ultrasonic radar detection method, the theoretical basis of which is that ultrasonic waves can be effectively returned at fixed points or inflection points of irregular obstacles, but because the obstacle's reflecting surface is too small, it is generally filtered out and cannot be identified; other reflecting surfaces of irregular obstacles have specific reflection angles, so most radar waves are reflected and cannot be captured by any ultrasonic radar. Simply increasing the sensitivity of the probe or lowering the filtering threshold will inevitably lead to the identification of ultrasonic waves reflected by the ground or the environment, resulting in obvious false alarms, which is obviously undesirable. The present invention uses an algorithm to identify unrecognizable areas caused by obstacles with too small reflecting surfaces, and can also use an algorithm to identify unrecognizable reflection areas due to irregular reflecting surfaces. If the two situations are strongly correlated in certain circumstances, irregular obstacles can be identified through specific correlation relationships. In order to implement the control method of the present invention, the entire vehicle system needs to use each ultrasonic radar to access a controller with high algorithm storage and editing capabilities (such as an intelligent driving domain controller); the algorithm of the present invention is built into the controller, and the ultrasonic radar system's own algorithm is not used. Instead, the received return ultrasonic wave is sampled through the intelligent driving domain controller, and the received sampling value and the sampling value of the transmitted waveform are correlated to obtain accurate calculation results, thereby maximizing the anti-interference capability.

[0054] The relevant formulas and derivation process of the present invention are as follows:

[0055] The radar ultrasonic emission signal, and the basic mathematical expression formula of the radar ultrasonic wave is as follows:

[0056]

[0057] Where in the formula:

[0058] S(t) is the mathematical expression of the ultrasonic wave function, where the subscript t represents the emission flag, and the subscript r represents the reception flag. Therefore, S t (t) is the expression of the emitted ultrasonic wave; t is the cycle time; T p is the cycle of a single loop in this embodiment; f c is the actual ultrasonic wave frequency (not the propagation frequency) in the ultrasonic wave function mathematical expression. Its subscript c is the actual representation symbol. Specifically, the changing value is represented by the subscript t as the emission flag; A1 is the power adjustment parameter of the ultrasonic wave function, which can adjust the strength of the emitted ultrasonic wave during vehicle model calibration and is the amplitude in the mathematical expression; where K r is the frequency conversion coefficient; where the cycle T of a single loop p refers to a unit signal cycle emitted by the ultrasonic radar, which is not emitted cyclically. The ultrasonic wave function mathematical expression T p is equivalent to T in the ordinary function m .

[0059] It can be understood that when the ultrasonic wave emitted by the ultrasonic radar encounters multiple reflection targets, these targets will each reflect the ultrasonic wave back, forming multiple echo signals. These echo signals will be received by the ultrasonic radar and used for subsequent target detection and positioning. If there are multiple targets in space, these signals will have different differences, and the position, distance, speed and other parameters of the targets will be judged according to information such as the signal strength and time delay. When there are multiple targets, the basic mathematical expression formula (ultrasonic radar reflection target function) of the ultrasonic wave received by the ultrasonic radar is as follows:

[0060]

[0061] Where in the formula: τ k is the adjustment time, which is the time delay of the ultrasonic wave signal reflected by the k-th target; c is the speed of sound; R is the distance, and the subscript R 0k represents the initial distance between the ultrasonic wave emission to the target and the ultrasonic radar during the acquisition cycle of the k-th target due to target movement. V k is the target speed extracted at time k.

[0062] Where τ k The derivation process of the adjustment time is as follows:

[0063] The time delay τ kThis is because it takes a certain amount of time for the ultrasonic wave to be transmitted and received, and this time is related to the distance R of the target 0k and the speed of sound c. When the target is stationary, but when the target is moving, we need to consider the influence of the target speed V k on the distance measurement. Assume that at the moment t = 0 when the ultrasonic wave is transmitted, the initial distance between the target and the radar is R 0k . At time t, the target has moved a distance of V k t due to its movement. Therefore, the actual distance between the target and the radar at time t is R k = R 0k - V k t (here it is assumed that the target moving towards the radar direction is the negative direction, so it is subtracting V k t). So the time delay τ k can be expressed as: where for simplicity in calculating the ratio of V k and c, let

[0064] The rect function usually represents the rectangular function, which is a function with a value of 1 within a specific interval and a value of 0 in other intervals. The rectangular function takes a value of 1 within a certain interval and a value of 0 outside that interval. Therefore, the entire expression represents the sum of a series of weighted rectangular functions, where the weight of each rectangular function is σ k , and the position and time scale are determined by τ k and T p Such an expression is very common in signal processing, communication, and radar systems for describing the shapes and characteristics of various signals.

[0065] After filtering, its expression is:

[0066]

[0067] Substituting the above filtered ultrasonic radar reflected target function gives:

[0068]

[0069] After ignoring the quadratic terms:

[0070]

[0071] In the expression after ignoring the quadratic terms, the instantaneous phase is:

[0072]

[0073] The instantaneous frequency f kIt is the derivative of the instantaneous phase with respect to time, representing the instantaneous frequency of the ultrasonic signal reflected by the k-th target, and is defined as Substitute the instantaneous phase into the above formula to obtain: That is:

[0074] f k = K r τ0t - f d

[0075] Obtain

[0076] f k The expression also contains an additional term In order to more accurately describe the instantaneous frequency of the echo signal received by the radar in the case of target movement. In practical applications, in order to accurately obtain the speed and distance information of the target, complex processing and analysis of the radar signal are required. The additional term is intended to more accurately describe the instantaneous frequency of the echo signal in the case of target movement. Where Δf is the frequency change amount, and T m is a certain period related to modulation, and combine it with Combine:

[0077]

[0078] Generally speaking, compared with the prior art, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0079] (1) The present invention provides an accurate multi-element ultrasonic radar detection method, which has high ranging accuracy, can also improve the ranging accuracy, reduce the risk of vehicle collision with obstacles, and ensure the safety of vehicles and pedestrians.

[0080] (2) The present invention provides an accurate multi-element ultrasonic radar detection method, which can break through the bondage of a single and unchanged ultrasonic phase difference, and by controlling the ultrasonic radar to measure the frequency and phase difference of the reflected wave, quickly calculate the speed of the obstacle.

[0081] (3) The present invention provides an accurate multi-element ultrasonic radar detection method, which can complete the performance improvement of the reverse radar system at zero cost and without increasing the cost under the condition of the same function configuration; and this method is simple and practical, applicable to all vehicle models, can interact with various models of reverse radar systems, and operates modularly. Description of the Drawings

[0082] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The accompanying drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0083] Figure 1 It is a schematic flow chart of an accurate multi-element ultrasonic radar detection method in Embodiment 1 of the present invention.

[0084] Figure 2 It is a schematic diagram of the frequency function of the ultrasonic wave emitted and the frequency function of the reflected ultrasonic wave in Embodiment 1 of the present invention.

[0085] Figure 3 It is a schematic diagram of obtaining the ultrasonic difference frequency according to the difference between the frequency function of the ultrasonic wave emitted and the frequency function of the reflected ultrasonic wave in Embodiment 1 of the present invention.

[0086] Figure 4 It is a schematic flow chart of an accurate multi-element ultrasonic radar detection method in Embodiment 2 of the present invention. Detailed implementation manners

[0087] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0088] It should be understood that the magnitude of the sequence numbers of the steps in the embodiments does not mean the order of execution. The execution order of each process should be determined according to its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0089] Embodiment 1

[0090] One aspect of the embodiments of the present application provides an accurate multi-element ultrasonic radar detection method. Please refer to Figure 1 , including:

[0091] S1. Control the ultrasonic radar of the target vehicle to emit ultrasonic waves to a stationary obstacle and receive the reflected waves, and obtain the unit signal period of the ultrasonic radar and the change value of the emission frequency within the unit signal period.

[0092] In the embodiments of the present application, it can be understood that the target vehicle is equipped with a reverse radar and a central controller. The ultrasonic radar has normal ultrasonic radar functions. When identifying weak radar echoes, the ultrasonic radar does not shield them and can still output characteristic echo signals to the central controller. The central controller is responsible for storing the ordinary reverse radar algorithm and the algorithm of the present invention, and is responsible for implementing the core inventive points involved in the present invention.

[0093] S2. Determine the frequency function of the transmitted ultrasonic wave and the frequency function of the reflected ultrasonic wave.

[0094] Specifically, it can be understood that in the embodiments of the present application, the frequency function of the transmitted ultrasonic wave is:

[0095]

[0096] where f t is the frequency of the transmitted ultrasonic wave; f0 is the frequency of the transmitted ultrasonic wave at time 0; t is the periodic time; T m is the unit signal period of the ultrasonic radar, that is, the minimum precision of time; 4Δf is the change value of the transmitted frequency within the unit signal period, where Δf is the minimum frequency change gradient.

[0097] Similarly, it can be understood that the frequency function of the reflected ultrasonic wave is:

[0098]

[0099] where f r is the frequency of the reflected ultrasonic wave; f0 is the frequency of the transmitted ultrasonic wave at time 0; t is the periodic time; T m is the unit signal period of the ultrasonic radar, that is, the minimum precision of time; 4Δf is the change value of the transmitted frequency within the unit signal period, where Δf is the minimum frequency change gradient; R is the distance between the target vehicle and the obstacle; c is the speed of sound.

[0100] S3. Obtain the ultrasonic beat frequency expression according to the difference between the frequency function of the transmitted ultrasonic wave and the frequency function of the reflected ultrasonic wave.

[0101] Specifically, it can be understood that in the embodiments of the present application, the method for obtaining the ultrasonic beat frequency expression according to the difference between the frequency function of the transmitted ultrasonic wave and the frequency function of the reflected ultrasonic wave is:

[0102]

[0103] where f b is the ultrasonic beat frequency.

[0104] S4. Calculate the distance between the target vehicle and the stationary obstacle based on the peak frequency of the ultrasonic beat frequency and the ultrasonic beat frequency expression.

[0105] Specifically, it can be understood that in the embodiments of the present application, the method for calculating the distance between the target vehicle and the stationary obstacle based on the peak frequency of the ultrasonic beat frequency and the ultrasonic beat frequency expression is as follows:

[0106] Obtained according to the ultrasonic beat frequency expression:

[0107]

[0108] Figure 2 It is a schematic diagram of the frequency function of the transmitted ultrasonic wave and the frequency function of the reflected ultrasonic wave in this embodiment. Figure 3 It is a schematic diagram of obtaining the ultrasonic beat frequency according to the difference between the frequency function of the transmitted ultrasonic wave and the frequency function of the reflected ultrasonic wave in this embodiment. As can be seen from Figure 3 It can be seen that when the ultrasonic beat frequency f b is the peak frequency f bav , the value of the ultrasonic beat frequency is stable and the duration is relatively long. For the convenience of calculation, the above ultrasonic beat frequency expression can be transformed into:

[0109]

[0110] Among them, f bav is the peak line value of f b , and f m is the frequency of the unit signal period T m . Substituting the value of f bav can calculate the distance R between the target vehicle and the obstacle.

[0111]

[0111] Among them, the accuracy of R is:

[0112]

[0113] Therefore, the resolution ρ R of the distance is:

[0114]

[0115] While the accuracy of radar ranging in the traditional scheme is:

[0116]

[0117] Among them, A is approximately the time accuracy of the wave emission period, about 1000 or so, which is much smaller than B. Therefore, the distance accuracy obtained by the method of the present invention is high.

[0118] In summary, this embodiment provides an accurate multi-element ultrasonic radar detection method. This method has high ranging accuracy, can also improve the ranging accuracy, reduce the risk of collision between the vehicle and the obstacle, and ensure the safety of the vehicle and pedestrians.

[0119] Embodiment 2

[0120] On the one hand, an embodiment of the present application provides an accurate multi-element ultrasonic radar detection method, including:

[0121] S1, controlling the ultrasonic radar of the target vehicle to emit ultrasonic waves to a stationary obstacle and receive the reflected waves, and obtaining the unit signal period of the ultrasonic radar and the change value of the emission frequency within the unit signal period.

[0122] In the embodiment of the present application, it can be understood that the target vehicle is equipped with a reverse radar and a central controller. The ultrasonic radar has normal ultrasonic radar functions. When identifying weak radar echoes, the ultrasonic radar does not shield them and can still output characteristic echo signals to the central controller. The central controller is responsible for storing the ordinary reverse radar algorithm and the algorithm of the present invention, and is responsible for the implementation of the core invention points involved in the present invention.

[0123] S2, determining the frequency function of the emitted ultrasonic waves and the frequency function of the reflected ultrasonic waves.

[0124] Specifically, it can be understood that in the embodiment of the present application, the frequency function of the emitted ultrasonic waves is:

[0125]

[0126] where f t is the frequency of the emitted ultrasonic waves; f0 is the frequency of the emitted ultrasonic waves at time 0; t is the cycle time; T m is the unit signal period of the ultrasonic radar, that is, the minimum accuracy of time; 4Δf is the change value of the emission frequency within the unit signal period, where Δf is the minimum frequency change gradient.

[0127] Similarly, it can be understood that the frequency function of the reflected ultrasonic waves is:

[0128]

[0129] where f r is the frequency of the reflected ultrasonic waves; f0 is the frequency of the emitted ultrasonic waves at time 0; t is the cycle time; T m is the unit signal period of the ultrasonic radar, that is, the minimum accuracy of time; 4Δf is the change value of the emission frequency within the unit signal period, where Δf is the minimum frequency change gradient; R is the distance between the target vehicle and the obstacle; c is the speed of sound.

[0130] S3, obtaining the ultrasonic difference frequency expression according to the difference between the frequency function of the emitted ultrasonic waves and the frequency function of the reflected ultrasonic waves.

[0131] Specifically, it can be understood that, in the embodiment of the present application, the method for obtaining the ultrasonic difference frequency expression according to the difference between the frequency function of the transmitted ultrasonic wave and the frequency function of the reflected ultrasonic wave is:

[0132]

[0133] where f b It is the ultrasonic difference frequency.

[0134] S4, calculating the distance between the target vehicle and the obstacle based on the peak frequency of the ultrasonic difference frequency and the ultrasonic difference frequency expression.

[0135] Specifically, it can be understood that, in the embodiment of the present application, the method for calculating the distance between the target vehicle and the obstacle based on the peak frequency of the ultrasonic beat frequency and the ultrasonic beat frequency expression is:

[0136] According to the ultrasonic difference frequency expression, we can get:

[0137]

[0138] When the ultrasonic difference frequency f b is the peak frequency f bav When , the ultrasonic difference frequency value is stable and lasts for a long time. For the convenience of calculation, the above ultrasonic difference frequency expression can be converted into:

[0139]

[0140] Among them, f bav f b Peak line value, f m is the unit signal period T m The frequency of f bav The distance R between the target vehicle and the obstacle can be calculated based on the value.

[0141] Furthermore, this embodiment also provides optimization of this method.

[0142] In the embodiments of the present application:

[0143]

[0144] Where c is the speed of sound. It can be seen that the larger 8Δf is, the higher the accuracy of R is. The fixed error △R is inversely proportional to the frequency deviation △f, but has nothing to do with the distance R and the operating frequency f of the ultrasonic radar. To improve the accuracy of ranging, the ultrasonic radar transmission can be set to:

[0145]

[0146] Among them, U tThe instantaneous voltage of the ultrasonic emission signal can characterize the amplitude; f0 is the frequency of the emitted ultrasonic wave at time 0; t is the cycle time; f m is the frequency of the unit signal.

[0147] Embodiment 3

[0148] One aspect of the embodiments of the present application provides an accurate multi-element ultrasonic radar detection method. Please refer to Figure 4 , including:

[0149] S1, controlling the ultrasonic radar of the target vehicle to emit ultrasonic waves to a moving obstacle and receive the reflected waves, and obtaining the unit signal period of the ultrasonic radar and the change value of the emission frequency within the unit signal period.

[0150] In the embodiments of the present application, it can be understood that the target vehicle is equipped with a reverse radar and a central controller. The ultrasonic radar has normal ultrasonic radar functions. When identifying weak radar echoes, the ultrasonic radar does not shield them and can still output characteristic echo signals to the central controller. The central controller is responsible for storing the ordinary reverse radar algorithm and the algorithm of the present invention, and is responsible for the implementation of the core invention points involved in the present invention.

[0151] S2, determining the frequency function of the emitted ultrasonic wave and the frequency function of the reflected ultrasonic wave.

[0152] Specifically, it can be understood that in the embodiments of the present application, the frequency function of the emitted ultrasonic wave is:

[0153]

[0154] where f t is the frequency of the emitted ultrasonic wave; f0 is the frequency of the emitted ultrasonic wave at time 0; t is the cycle time; T m is the unit signal period of the ultrasonic radar, that is, the minimum accuracy of time; 4Δf is the change value of the emission frequency within the unit signal period, where Δf is the minimum frequency change gradient.

[0155] Similarly, it can be understood that the frequency function of the reflected ultrasonic wave is:

[0156]

[0157] where f r is the frequency of the reflected ultrasonic wave; f0 is the frequency of the emitted ultrasonic wave at time 0; f d is the median ultrasonic frequency, that is, half of the sum of the maximum and minimum ultrasonic frequencies, used to distinguish the rising and falling trends of the ultrasonic wave; t is the cycle time; T mis the unit signal period of the ultrasonic radar, that is, the minimum precision of time; 4Δf is the change value of the transmission frequency within the unit signal period, where Δf is the minimum frequency change gradient; R is the distance between the target vehicle and the obstacle; c is the speed of sound.

[0158] S3. Obtain the ultrasonic difference frequency expressions in the ascending frequency band and the descending frequency band according to the difference between the frequency function of the transmitted ultrasonic wave and the frequency function of the reflected ultrasonic wave.

[0159] Specifically, it can be understood that in the embodiment of the present application, the method for obtaining the ultrasonic difference frequency expressions in the ascending frequency band and the descending frequency band according to the difference between the frequency function of the transmitted ultrasonic wave and the frequency function of the reflected ultrasonic wave is as follows:

[0160] Ascending frequency band:

[0161]

[0162] Descending frequency band:

[0163]

[0164] where; f b+ is the ultrasonic difference frequency expression in the ascending frequency band; f b- is the ultrasonic difference frequency expression in the descending frequency band.

[0165] S4. Calculate the speed of the moving obstacle based on the ultrasonic difference frequency expressions in the ascending frequency band and the descending frequency band.

[0166] Specifically, it can be understood that in the embodiment of the present application, the method for calculating the speed of the moving obstacle based on the ultrasonic difference frequency expressions in the ascending frequency band and the descending frequency band is as follows:

[0167] According to the ultrasonic difference frequency expressions in the ascending frequency band and the descending frequency band, it is obtained that:

[0168]

[0169] It is obtained that:

[0170]

[0171] where v is the speed of the obstacle; λ is the wavelength of the ultrasonic wave; f tm is the modulation frequency of the ultrasonic transmission signal.

[0172] In summary, the embodiment of the present application also provides an accurate multi-element ultrasonic radar detection method, which can break through the bondage of a single and unchanging ultrasonic phase difference, and quickly calculate the speed of the obstacle by controlling the ultrasonic radar to measure the frequency and phase difference of the reflected wave.

[0173] It should be noted that according to the needs of implementation, each step described in this application can be split into more steps, or two or more steps or partial operations of steps can be combined into new steps to achieve the purpose of the present invention.

[0174] Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An accurate multi-element ultrasonic radar detection method, characterized in that, Including: Controlling the ultrasonic radar of the target vehicle to emit ultrasonic waves towards a stationary obstacle and receive the reflected waves, and obtaining the unit signal period of the ultrasonic radar and the change value of the emission frequency within the unit signal period; Determining the frequency function of the emitted ultrasonic waves and the frequency function of the reflected ultrasonic waves; Obtaining an ultrasonic difference frequency expression based on the difference between the frequency function of the emitted ultrasonic waves and the frequency function of the reflected ultrasonic waves; Calculating the distance between the target vehicle and the stationary obstacle based on the peak frequency of the ultrasonic difference frequency and the ultrasonic difference frequency expression.

2. An accurate multi-factor ultrasonic radar detection method, characterized in that, Including: Controlling the ultrasonic radar of the target vehicle to emit ultrasonic waves towards a moving obstacle and receive the reflected waves, and obtaining the unit signal period of the ultrasonic radar and the change value of the emission frequency within the unit signal period; Determining the frequency function of the emitted ultrasonic waves and the frequency function of the reflected ultrasonic waves; Obtaining an ultrasonic difference frequency expression in the ascending frequency band and an ultrasonic difference frequency expression in the descending frequency band based on the difference between the frequency function of the emitted ultrasonic waves and the frequency function of the reflected ultrasonic waves; Calculating the speed of the moving obstacle based on the ultrasonic difference frequency expression in the ascending frequency band and the ultrasonic difference frequency expression in the descending frequency band.

3. A precise multi-factor ultrasonic radar detection method according to claim 1, characterized in that The frequency function of the emitted ultrasonic waves is: Among them, f t is the frequency of the ultrasonic wave emitted; f0 is the frequency of the ultrasonic wave at the moment of 0; t is the periodic moment; T m is the unit signal period of the ultrasonic radar, that is, the minimum accuracy of time; 4Δf is the change value of the emission frequency within the unit signal period, where Δf is the minimum frequency change gradient.

4. The precise multi-element ultrasonic radar detection method according to claim 3, characterized in that, The frequency function of the reflected ultrasonic waves is: Among them, f r is the frequency of the reflected ultrasonic wave; f0 is the frequency of the transmitted ultrasonic wave at time 0; t is the cycle time; T m is the unit signal period of the ultrasonic radar, that is, the minimum precision of time; 4Δf is the change value of the transmission frequency within the unit signal period, where Δf is the minimum frequency change gradient; R is the distance between the target vehicle and the obstacle; c is the speed of sound.

5. An accurate multi-element ultrasonic radar detection method according to claim 4, characterized in that The method for obtaining the ultrasonic difference frequency expression based on the difference between the frequency function of the emitted ultrasonic waves and the frequency function of the reflected ultrasonic waves is: where f b is the ultrasonic beat frequency.

6. An accurate multi-factor ultrasonic radar detection method according to claim 5, characterized in that The method for calculating the distance between the target vehicle and the stationary obstacle based on the peak frequency of the ultrasonic difference frequency and the ultrasonic difference frequency expression is: According to the ultrasonic difference frequency expression, it is obtained that: When the ultrasonic difference frequency is the peak frequency, for the convenience of calculation, the ultrasonic difference frequency expression can be transformed into: where, f bav is the peak line value of f b , and f m is the frequency of the unit signal period T m .

7. A precise multi-element ultrasonic radar detection method according to claim 2, characterized in that The frequency function of the emitted ultrasonic waves is: Among them, f t is the frequency of the ultrasonic wave emitted; f t is the frequency at the moment when the ultrasonic wave is emitted at time 0; t is the cycle moment; T m is the unit signal period of the ultrasonic radar, that is, the minimum precision of time; 4Δf is the change value of the emission frequency within the unit signal period, where Δf is the minimum frequency change gradient.

8. An accurate multi-element ultrasonic radar detection method according to claim 7, characterized in that, The frequency function of the reflected ultrasonic waves is: Among them, f r is the frequency of the reflected ultrasonic wave; f0 is the frequency of the transmitted ultrasonic wave at time 0; f d is the median of the ultrasonic wave frequencies, that is, half of the sum of the maximum and minimum values of the ultrasonic wave frequencies, which is used to distinguish the rising and falling trends of the ultrasonic waves; t is the cycle time; T m is the unit signal period of the ultrasonic radar, that is, the minimum precision of time; 4Δf is the change value of the transmission frequency within the unit signal period, where Δf is the minimum frequency change gradient; R is the distance between the target vehicle and the obstacle; c is the speed of sound.

9. A precise multi-factor ultrasonic radar detection method according to claim 8, characterized in that The method for obtaining the ultrasonic difference frequency expression in the ascending frequency band and the ultrasonic difference frequency expression in the descending frequency band based on the difference between the frequency function of the emitted ultrasonic waves and the frequency function of the reflected ultrasonic waves is: Ascending frequency band: Descending frequency band: Wherein; f b+ is the ultrasonic difference frequency expression in the ascending frequency band; f b- is the ultrasonic difference frequency expression in the descending frequency band.

10. The precise multi-element ultrasonic radar detection method according to claim 9, characterized in that, The method for calculating the speed of the moving obstacle based on the ultrasonic difference frequency expression in the ascending frequency band and the ultrasonic difference frequency expression in the descending frequency band is: According to the ultrasonic difference frequency expression in the ascending frequency band and the ultrasonic difference frequency expression in the descending frequency band, it is obtained that: Obtaining: where v is the speed of the obstacle; λ is the wavelength of the ultrasonic wave; f tm is the modulation frequency of the ultrasonic emission signal.

11. A precise multi-element ultrasonic radar detection method according to claim 1 or 2, characterized in that The ultrasonic radar has normal ultrasonic radar functions. When the ultrasonic radar identifies a weak radar echo, it does not shield it and still outputs a characteristic echo signal.

12. A precise multi-factor ultrasonic radar detection method according to claim 6, characterized in that The emission setting of the ultrasonic radar is: Among them, U t is the instantaneous voltage of the ultrasonic emission signal, which can characterize the amplitude; f0 is the frequency at the moment of 0 of the emitted ultrasonic wave; t is the periodic moment; f m is the frequency of the unit signal.

Images