CN114179809A - Radar data-based collision time calculation method and device, vehicle and medium - Google Patents
Radar data-based collision time calculation method and device, vehicle and medium Download PDFInfo
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Abstract
The invention discloses a method, a device, a vehicle and a medium for calculating collision time based on radar data, wherein a quadratic equation of distance and time is established based on a kinematic formula of relative acceleration; acquiring radar data monitored by a millimeter wave radar; the radar data at least comprises the relative distance between the vehicle and the front vehicle and the current time corresponding to the sampling relative distance; estimating the coefficients of the quadratic equation according to the radar data and the estimation matrix to obtain a plurality of estimation coefficients of the quadratic equation; calculating through the quadratic equation according to the estimation coefficient to obtain the prediction time when the relative distance is zero; and carrying out collision prediction processing according to the current time and the predicted time to obtain collision time. The invention integrates the relative acceleration change of the two workshops into the calculation of the collision time, can greatly improve the calculation precision of the collision time, simultaneously reduces the influence of clutter, and ensures the safety of the vehicle during running.
Description
Technical Field
The invention relates to the technical field of automatic driving, in particular to a method and a device for calculating collision time based on radar data, a vehicle and a medium.
Background
The millimeter wave radar is a sensor widely used in an auxiliary driving system and an automatic driving system, and is mainly applied to functions of an Adaptive Cruise Control (ACC), an automatic Braking system (AEB) and the like in medium and long distances; the self-adaptive cruise control can reduce driving load caused by frequent starting/stopping operations during traffic jam, the safe vehicle distance model is used as a main control strategy of an ACC system, if the control strategy is too conservative, the jam is caused, and if the control strategy is too aggressive, rear-end collision is easily caused; in the safe inter-vehicle distance model, Time To Collision (TTC) is a core index of the model, and means that assuming that the current relative speed is maintained, the time required for two vehicles to collide with each other is required, and after the collision time is obtained, other control strategies of the vehicles can be triggered to realize automatic driving of the vehicles; for example, an automatic braking system control strategy for a passenger vehicle would need to be triggered based on this time to collision; for another example, some AEB systems trigger emergency braking 1.3 seconds before a collision; for another example, the problem of limitations of physical contact-based airbag deployment algorithms can be solved by predicting accurate collision times, improving occupant safety.
In the prior art, a millimeter wave radar obtains a relative distance from a front vehicle, differentiates the relative distance from the front vehicle into a relative speed, and divides the relative distance by the relative speed to obtain collision time between the front vehicle and an obstacle; however, distance signals measured by the millimeter wave radar are easily interfered by external noise waves, and if the relative distance is directly differentiated, the obtained relative speed amplifies the noise waves, so that the calculated collision time is inaccurate, and the safety of the vehicle during running is influenced.
Therefore, a method, an apparatus, a vehicle and a medium for calculating collision time based on radar data are needed, which integrate the relative acceleration changes between two vehicles into the method for calculating collision time, improve the calculation accuracy of collision time, reduce the influence of noise and ensure the safety of the vehicle during driving.
Disclosure of Invention
In view of the problems in the prior art, the invention provides a method and a device for calculating collision time based on radar data, a vehicle and a medium, wherein the method and the device are used for integrating the relative acceleration change of two workshops into the method for calculating the collision time, so that the calculation precision of the collision time can be greatly improved, the estimated collision time is closer to the real collision time, meanwhile, the influence of clutter is reduced, and the safety of the vehicle during running is ensured. The technical scheme is as follows:
in one aspect, the invention provides a method for calculating a collision time based on radar data, comprising the following steps:
establishing a quadratic equation of distance and time based on a kinematic formula of relative acceleration;
acquiring radar data monitored by a millimeter wave radar; the radar data at least comprises the relative distance between the vehicle and the front vehicle and the current time corresponding to the sampling relative distance;
estimating the coefficients of the quadratic equation according to the radar data and the estimation matrix to obtain a plurality of estimation coefficients of the quadratic equation;
calculating through the quadratic equation according to the estimation coefficient to obtain the prediction time when the relative distance is zero;
and carrying out collision prediction processing according to the current time and the predicted time to obtain collision time.
Further, the estimation matrix is a covariance matrix, and an initial value of the estimation matrix is an identity matrix.
Further, the estimating the coefficients of the quadratic equation according to the radar data and the estimation matrix to obtain a plurality of estimation coefficients of the quadratic equation includes:
performing preliminary estimation processing according to the radar data and the estimation matrix of the sampling point at the previous moment to obtain a weight factor of the current sampling point; wherein the sampling points correspond to the radar data one to one;
estimating according to the radar data, the weighting factor and the coefficient state of the sampling point at the previous moment to obtain the current coefficient state; wherein the coefficient state is composed of a plurality of the estimation coefficients.
Further, after the obtaining of the predicted time when the relative distance is zero by performing the calculation through the quadratic equation according to the estimation coefficient, the method further includes:
judging whether the predicted time is greater than the current time or not to select the value of the predicted time; wherein the number of the prediction time is two;
if the two predicted moments are both greater than the current moment, the predicted moment is the minimum value of the two predicted moments;
and if only one predicted time is greater than the current time, the predicted time is a value greater than the current time.
Further, after the obtaining of the predicted time when the relative distance is zero by performing the calculation through the quadratic equation according to the estimation coefficient, the method further includes:
judging whether the value of the predicted time is an imaginary number or not;
if the value of the predicted time is an imaginary number, setting the predicted time as a self-adaptive constant;
and if the value of the predicted time is not an imaginary number, executing the step of judging whether the predicted time is greater than the current time so as to select the value of the predicted time.
Further, the acquiring radar data monitored by the millimeter wave radar further includes:
acquiring the radar data monitored by the millimeter wave radar within a preset time interval;
and translating the current moment according to the size of the preset time interval to obtain the translated current moment, and calculating the collision time in the preset time interval.
Further, after the translating the current time according to the size of the preset time interval to obtain the translated current time and calculating the collision time within the preset time interval, the method further includes:
carrying out translation processing on the preset time interval;
and calculating the collision time in the translated preset time interval according to the coefficient state estimated from the previous preset time interval as an initial coefficient state.
In another aspect, the present invention provides a device for calculating a collision time based on radar data, including at least:
the building module is used for building a quadratic equation of distance and time based on a kinematic formula of relative acceleration;
the acquisition module is used for acquiring radar data monitored by the millimeter wave radar; the radar data at least comprises the relative distance between the vehicle and the front vehicle and the current time corresponding to the sampling relative distance;
the estimation processing module is used for estimating the coefficients of the quadratic equation according to the radar data and the estimation matrix to obtain a plurality of estimation coefficients of the quadratic equation;
the calculation module is used for calculating through the quadratic equation according to the estimation coefficient to obtain the prediction time when the relative distance is zero;
and the collision prediction processing module is used for performing collision prediction processing according to the current time and the prediction time to obtain collision time.
The invention also provides a vehicle, which comprises the device for calculating the collision time based on the radar data, and the device is integrated in a controller of the vehicle.
The present invention also provides a medium having at least one instruction or at least one program stored therein, which is loaded and executed by a processor to implement the method for calculating a collision time based on radar data as described above.
The implementation of the invention has the following beneficial effects:
1. according to the method, the relative acceleration change of the two workshops is integrated into the collision time calculation method, so that the calculation accuracy of the collision time can be greatly improved, the estimated collision time is closer to the real collision time, meanwhile, the influence of clutter can be reduced, and the accuracy of the estimated collision time is further improved; and the improvement of the accuracy of the collision time enables the vehicle to have redundant time to decide the time point for intervening in controlling the vehicle, and the decision real-time performance and the reliability of the vehicle driving strategy are improved, so that the safety of the vehicle in running is ensured.
2. According to the method, the estimation matrix and the weight factor are utilized to combine the data of the sampling points at the previous moment and the data of the sampling points at the next moment, the coefficient state of the current moment is estimated by utilizing the data of the estimation matrix, the coefficient state and the like of the sampling points at the previous moment, the calculation error can be further reduced, the estimated coefficient state is enabled to be closer to a true value, and the accuracy of the predicted moment and the collision time obtained by calculation is further improved.
3. The method can estimate the instantaneous collision time, can estimate the relative distance sampling points in a period of time, obtains the collision time in any period of time, and has strong applicability.
Drawings
In order to more clearly illustrate the technical solution in the embodiments of the present invention, the drawings used in the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.
FIG. 1 is a logic structure diagram of a method for calculating a collision time based on radar data according to one possible embodiment of the present invention;
FIG. 2 is a schematic flow chart of an estimation process according to one possible embodiment of the present invention;
FIG. 3 is a logical block diagram of a method for selecting a predicted time in one possible embodiment of the present invention;
FIG. 4 is a schematic diagram illustrating simulation verification of accuracy of a method for calculating a time-to-collision based on radar data according to one possible embodiment of the present invention;
fig. 5 is a schematic structural diagram of a device for calculating a collision time based on radar data according to a possible embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments, and therefore, the present invention is not to be construed as being limited thereby. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention can be practiced otherwise than as specifically illustrated or described below. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or server that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
In the prior art, distance information measured by millimeter radar waves is easily interfered by external clutter, and if the relative distance is directly differentiated, the clutter is amplified by the obtained relative speed, so that the calculated collision time is inaccurate; to solve this problem, this embodiment provides a method for calculating a collision time based on radar data, which can be applied to a device for calculating a collision time based on radar data according to an embodiment of the present invention, and the device for calculating a collision time based on radar data can be configured in a controller of a vehicle, and takes into account the influence of a change in relative acceleration, the controller of the vehicle establishes a quadratic equation between distance and time in advance, when a calculation requirement for a collision time occurs, the controller obtains radar data monitored by a millimeter wave radar, and then the controller controls the calculation to perform an estimation process on each coefficient in the quadratic equation according to the radar data and an estimation matrix that changes with time, so as to obtain a plurality of estimation coefficients that are closest to a true value, and then substitutes the estimation coefficients into the quadratic equation to perform the calculation, and obtaining the predicted time when the relative distance is zero, namely the vehicle collides with the front vehicle, and then the difference value between the predicted time and the current time is the collision time.
The following describes in detail the technical solution of the embodiment of the present invention, with reference to the accompanying fig. 1 of the specification, the method includes:
and S101, establishing a quadratic equation of the distance and the time based on a kinematic formula of the relative acceleration.
In kinematics, a quadratic function is usually used to solve the pursuit problem in kinematics, such as time of encounter, nearest or farthest distance, and the distance Δ s between two pursuit objects is just a quadratic function of time t:
Δs＝at2+bt+c
where the horizontal axis of the function is time and the vertical axis is the relative distance between two chasing objects.
And comparing the quadratic function with a kinematic formula, a kinematic formula of distance and time can be obtained:
dk+1＝0.5Akt2+Vkt+dk
wherein A iskAs relative acceleration, VkAs relative velocity, dkAre relative distances.
Then in this step, a quadratic equation of distance versus time is established as:
wherein, ak、bk、ckThe estimation coefficients which are quadratic equations are respectively called quadratic estimation coefficient, first estimation coefficient and zero estimation coefficient, k represents the kth sampling point, the sampling point refers to the corresponding sampling point when the relative distance is sampled in the subsequent S103 step, and the information of the sampling point includes packetAnd S103, including the radar data acquired in the step.
As can be seen from the comparison between the kinematic formula and the quadratic equation, the following relationship exists between the relative acceleration and the quadratic estimation coefficient to be estimated: a. thek＝2ak。
S103, acquiring radar data monitored by the millimeter wave radar; the radar data at least comprises the relative distance between the vehicle and the front vehicle and the current time corresponding to the sampling relative distance.
When a vehicle or an obstacle in front is monitored, the relative distance between the vehicle and the front vehicle is continuously monitored by the millimeter wave radar, and the relative distance and the current moment when the relative distance is monitored are continuously output to the controller for subsequent calculation; then, from time 0 to tkAll relative distance data between moments are estimated, and the relative distance measured by the millimeter wave radar can be expressed by a quadratic equation related to the moments as follows:
wherein the content of the first and second substances,
represents a known time vector;
represents the state of the coefficient to be estimated, and is also a vector; t is tkThe current time representing the current kth sampling point, that is, the time when the millimeter wave radar monitors radar data, belongs to real-world time (equivalent to the x-axis in the quadratic function).
And S105, estimating the coefficients of the quadratic equation according to the radar data and the estimation matrix to obtain a plurality of estimation coefficients of the quadratic equation.
Specifically, in the present embodiment, the estimation matrix is a covariance matrix, and the estimation matrix changes as the current time or the sampling point changes, and the estimation matrix is set to P, and the initial value of the estimation matrix is set to the identity matrix I, that is, the identity matrix I at time 0
In this step, the estimation process of the coefficient requires the use of information of the previous time sampling point, for example, the state of the coefficient of the previous time sampling point
To calculate the coefficient state of the sampling point at the current moment
Through a series of estimation formulas, the cyclic calculation can be repeated from the time 0, and the coefficient state of the sampling point at the current time, namely a plurality of estimation coefficients at the current time, is obtained through estimation.
And S107, calculating through the quadratic equation according to the estimation coefficient to obtain the prediction time when the relative distance is zero.
The predicted time represents a time at which the host vehicle and the preceding vehicle are likely to collide with each other, which is calculated by the calculation method of the present invention, and the predicted time is set as
Then, the estimated coefficient a estimated in step S105 is usedk、bk、ckSubstituting into the quadratic equation and making the relative distance at that time
Is 0, i.e. akt2+bkt+ckIf 0, the formula of the predicted time can be calculated by the quadratic equation as follows:
and S109, performing collision prediction processing according to the current time and the predicted time to obtain collision time.
In this step, the time difference between the current time and the predicted time can be directly calculated by subtracting the current time from the predicted time, and the Time To Collision (TTC), i.e. the Time To Collision (TTC), can be directly obtained
And the influence of the relative acceleration is considered in the whole calculation process, so that the calculated time to collision TTC is closer to a real time to collision value compared with the time to collision without considering the relative acceleration.
Specifically, as shown in fig. 2 in the specification, in one possible embodiment of the specification, the estimating, according to the radar data and the estimation matrix, the coefficients of the quadratic equation are estimated to obtain a plurality of estimated coefficients of the quadratic equation, that is, the step S105 may further specifically include:
s202, performing primary estimation processing according to the radar data and the estimation matrix of the sampling point at the previous moment to obtain a weight factor of the current sampling point; wherein the sampling points correspond to the radar data one to one.
S204, estimating according to the radar data, the weight factor and the coefficient state of the sampling point at the previous moment to obtain the current coefficient state; wherein the coefficient state is composed of a plurality of the estimation coefficients.
As explained in step S105 above, the coefficient state of the sampling point at the previous time is used
To calculate the coefficient state of the sampling point at the current moment
The estimation formula is:
wherein, KkIs the weight factor, R, of the current k-th sample pointkRepresents the relative distance, P, of the current kth sample pointkIs the estimation matrix of the current k-th sample point and λ is the forgetting factor.
The coefficient state of the kth sampling point can be obtained by repeated and cyclic calculation from the moment 0 through the three estimation formulas; taking the first sampling point as an example, can
Using the state of coefficients of the sampling point at the previous moment
That is, the coefficient state at time 0 indicates that, in the method for calculating a collision time based on radar data according to the present invention, the data at time 0 is set as an initial value and R is used as the initial value0The initial value of the coefficient state is set as the relative distance initial value measured by the millimeter wave radar
Then the weighting factor of the first sample point can be obtained by step S202 as follows:
wherein, P0Is represented by an identity matrix, and
the time vector of the first sampling point is the current time t acquired by the millimeter wave radar1And (4) obtaining.
Will K1Substituting the estimation formula of the coefficient state, the coefficient state of the first sampling point can be obtained by the step S204 as follows:
in addition, during the estimation process, the estimation vector is also changed, and the estimation vector of the first sampling point is:
the coefficient state and the estimation vector of the current first sampling point can be obtained through the estimation formulas, and the two estimation results can be further substituted into the three estimation formulas to estimate the weight factor and the estimation vector of the second sampling point at the next moment so as to obtain the coefficient state of the second sampling point; by analogy, the weight factor, the estimation vector and the coefficient state of the kth sampling point can be estimated and obtained through continuous calculation, the estimation error is small, and the estimated coefficient vector, namely the estimation coefficient a can be obtainedk、bk、ckThe actual value is approached to the maximum extent, so that the finally calculated collision time can be ensured to approach the actual value to the maximum extent, and the accuracy and the reliability are high.
Specifically, as shown in fig. 3 in the specification, in one possible embodiment of the specification, after the obtaining of the predicted time when the relative distance is zero by the calculation according to the estimation coefficient through the quadratic equation, that is, after step S107 and before step S109, the method further includes:
s305, judging whether the predicted time is larger than the current time or not to select the value of the predicted time; wherein the prediction time has two values.
S307, if the two predicted moments are both larger than the current moment, the predicted moment is the minimum value of the two predicted moments.
S309, if only one predicted time is larger than the current time, the predicted time is a value larger than the current time.
In kinematics, two intersection points of an image of a quadratic function and an x-axis represent two meeting points in a pursuit process, if the image and the x-axis have no intersection point, the meeting is impossible, and the judgment can be carried out by using a discriminant
Judging whether the judgment result is greater than or equal to zero, if the judgment result is greater than zero, two solutions are provided, and the meeting is represented twice; if the discriminant is equal to zero, the image and the x axis have only one intersection point, namely the vertex is on the x axis, which indicates that the images meet each other only once in the pursuit process; if the discriminant is less than zero, the image and the x-axis do not have an intersection point, indicating that no encounter is possible.
Then in step S107, two predicted times are calculated
If the values of the two predicted times are both larger than the current time, because the vehicle is unlikely to collide with the preceding vehicle twice, the collision is already generated at the predicted time which is closer to the current time, and therefore the minimum value of the two predicted times is selected as the predicted time; in addition, if only one predicted time is greater than the current time, the other predicted time is less than the current time, and it is obviously impossible for a collision to occur before the current time, in which case the value of the one predicted time greater than the current time is selected as the predicted time to be calculated in step S109.
Specifically, as shown in fig. 3 in the specification, in a possible embodiment of the specification, after the obtaining of the predicted time when the relative distance is zero by the calculation according to the estimation coefficient through the quadratic equation, that is, after step S107 and before step S109, the method may further include:
s301, judging whether the value of the prediction time is an imaginary number.
And if the value of the predicted time is not an imaginary number, executing the step of judging whether the predicted time is greater than the current time so as to select the value of the predicted time.
That is, before step S305, the value of the predicted time is determined according to the discriminant of the quadratic function, and if b is the casek 2-4akckIf the value is not less than 0, the value representing the predicted time is not an imaginary number, and the step S305 may be performed to perform the subsequent determination.
And S303, if the value of the predicted time is an imaginary number, setting the predicted time as an adaptive constant.
If b isk 2-4akck<0, the value representing the predicted time is an imaginary number, at this time, the value of the predicted time can be set as a self-adaptive constant, and the self-adaptive constant can be set as any constant according to the difference between the actual vehicle type and the vehicle control system; in addition, in one possible embodiment of the present description, the adaptive constant may be set to 10, which both allows sufficient warning time and does not cause premature decision inefficiency.
Specifically, the method for calculating collision time based on radar data according to the present invention may not only calculate collision time at an instant time using the time 0 monitored by the radar as an initial value according to the above steps, but also calculate collision time at a relative distance sampling point within a period of time, where, in this case, the step S103, that is, the acquiring radar data monitored by the millimeter wave radar further includes:
acquiring the radar data monitored by the millimeter wave radar within a preset time interval;
and translating the current moment according to the size of the preset time interval to obtain the translated current moment, and calculating the collision time in the preset time interval.
In the process, with the addition of a new sampling point, the oldest sampling point is abandoned at the current moment corresponding to the translation sampling point; selecting a period of time as a preset time interval YkSetting the size of the preset time interval as n sampling points, setting the sampling time of each sampling point as T, and performing translation zeroing processing on the current time by taking the initial sampling point of the preset time interval as an initial value, wherein the initial current time of the preset time interval is 0; at the other end of the preset time interval, taking the latest sampling point k after translation as the final value of the preset time interval, and determining the occurrence time of the kth sampling point, namely the current time tk(n-1) T; corresponding the current time to a preset time interval YkThe preset time interval is represented by the following formula:
Yk＝[Rk-n+1K Rk-1 Rk]。
then, for a preset time interval YkInner sampling point, estimating coefficient state
The estimation formula of (c) can be expressed as:
wherein i represents a preset time interval YkThe ith sample point in.
And the current time t of the ith sample pointiTime vector of ═ i-1) T
Can be expressed by the following formula:
when the preset time interval Y is completedkAfter the calculation of the inner n sampling points, the method can obtain
At this time, the collision time is:
in a possible embodiment of the present specification, the method for calculating collision time based on radar data of the present invention may perform translation processing on a sampling point within a period of time to calculate collision time within a preset time interval, and may also perform translation processing on the preset time interval to calculate collision time within any preset time interval.
Specifically, after the translating the current time according to the size of the preset time interval to obtain the translated current time and calculating the collision time within the preset time interval, the method further includes:
carrying out translation processing on the preset time interval;
and calculating the collision time in the translated preset time interval according to the coefficient state estimated from the previous preset time interval as an initial coefficient state.
When the preset time interval is translated, the initial value of the translated preset time interval is changed, and then the coefficient state of the translated preset time interval is estimated
The estimation formula needs to use a new initial value of the coefficient state, which is already obtained by the calculation of the sampling points in a period of time
Taking into account the translation sample point (at the present moment by t)kBecomes tk+ T) can be utilized
Setting the initial value of the translated preset time interval, namely setting the initial value of the new coefficient state as follows:
and then, calculating according to the new initial value of the coefficient state to obtain the collision time of the translated preset time interval.
In addition, in order to verify the accuracy of the method for calculating the collision time based on the radar data, a driving state with relative acceleration between two vehicles is adopted for verification, in order to compare the difference of various algorithms, the collision time TTC is taken as 10s to be used as a basis for verifying whether the method is accurate, and the comparison result of simulation verification is shown in the attached figure 4 of the specification; the method for calculating the collision time based on the radar data is characterized in that the calculation result of the 2-State Kalman filter does not consider the influence of the relative acceleration of two vehicles, and the method for calculating the collision time based on the radar data considers the influence of the acceleration on the TTC (time to collision) time, so that the calculation result obtained by the method for calculating the collision time based on the radar data is obviously closer to an ideal State than the calculation result in the prior art on the estimation of the TTC; it is assumed that in the same situation (i.e., in the condition of FIG. 4), the preceding and following vehicles travel at the same vehicle speed first, and then the preceding vehicle travels at 2m/s2Deceleration of (1.5 m/s) after the front vehicle starts decelerating for one second and the rear vehicle starts decelerating for one second2The deceleration of the vehicle approaches the front vehicle, and it can be seen from fig. 4 that the present invention starts to change about the 32 nd secondThe calculation result is obviously superior to the calculation result of the 2-State Kalman filter which starts to change only about 33 seconds; meanwhile, as can be seen from the change of the time to collision TTC from the 33 th second to the 35 th second, the shock of the method is smaller and can be quickly close to the ideal time to collision TTC, which indicates that the method for calculating the time to collision based on radar data provided by the invention has a better warning effect relatively stable for the driver.
In addition, in the verification process, a group of optimal forgetting factors and the time interval size of a period of time for sampling can be found, the degree of closeness of the output result of the forgetting factors and the standard curve in an ideal state is judged by inputting the numerical values and the time intervals of different forgetting factors, if the deviation is excessive, the numerical values of the forgetting factors and the time intervals are adjusted until the output result meets the actual requirement, and the calculation accuracy and the reliability of the whole method are further improved.
According to the embodiment, the method for calculating the collision time based on the radar data has the following beneficial effects:
1. according to the method, the relative acceleration change of the two workshops is integrated into the collision time calculation method, so that the calculation accuracy of the collision time can be greatly improved, the estimated collision time is closer to the real collision time, meanwhile, the influence of clutter can be reduced, and the accuracy of the estimated collision time is further improved; and the improvement of the accuracy of the collision time enables the vehicle to have redundant time to decide the time point for intervening in controlling the vehicle, and the decision real-time performance and the reliability of the vehicle driving strategy are improved, so that the safety of the vehicle in running is ensured.
2. According to the method, the estimation matrix and the weight factor are utilized to combine the data of the sampling points at the previous moment and the data of the sampling points at the next moment, the coefficient state of the current moment is estimated by utilizing the data of the estimation matrix, the coefficient state and the like of the sampling points at the previous moment, the calculation error can be further reduced, the estimated coefficient state is enabled to be closer to a true value, and the accuracy of the predicted moment and the collision time obtained by calculation is further improved.
3. The method can estimate the instantaneous collision time, can estimate the relative distance sampling points in a period of time, obtains the collision time in any period of time, and has strong applicability.
Corresponding to the method for calculating time to collision based on radar data provided in the foregoing embodiment, an embodiment of the present invention further provides a device for calculating time to collision based on radar data, and since the device for calculating time to collision based on radar data provided in the embodiment of the present invention corresponds to the method for calculating time to collision based on radar data provided in the foregoing several embodiments, the foregoing embodiments of the method for calculating time to collision based on radar data are also applicable to the device for calculating time to collision based on radar data provided in the embodiment, and are not described in detail in the embodiment.
The device for calculating the time to collision based on the radar data according to the embodiment of the present invention can implement the method for calculating the time to collision based on the radar data according to the above method embodiment, as shown in fig. 5 of the specification, the system may include:
a building module 510, configured to build a quadratic equation between a distance and a time based on a kinematic formula of the relative acceleration;
an obtaining module 520, configured to obtain radar data monitored by a millimeter wave radar; the radar data at least comprises the relative distance between the vehicle and the front vehicle and the current time corresponding to the sampling relative distance;
an estimation processing module 530, configured to perform estimation processing on coefficients of the quadratic equation according to the radar data and an estimation matrix to obtain multiple estimation coefficients of the quadratic equation;
the calculating module 540 is configured to calculate according to the estimation coefficient by using the quadratic equation to obtain a predicted time when the relative distance is zero;
and a collision prediction processing module 550, configured to perform collision prediction processing according to the current time and the predicted time, so as to obtain collision time.
It should be noted that, when the apparatus provided in the foregoing embodiment implements the functions thereof, only the division of the functional modules is illustrated, and in practical applications, the functions may be distributed by different functional modules according to needs, that is, the internal structure of the apparatus may be divided into different functional modules to implement all or part of the functions described above. In addition, the apparatus and method embodiments provided by the above embodiments belong to the same concept, and specific implementation processes thereof are described in the method embodiments for details, which are not described herein again.
According to the radar data-based collision time calculation device, the quadratic equation of the change of the relative distance is adopted, the condition that the relative distance is zero is utilized, the influence of the relative acceleration between the vehicle and the front vehicle is considered, and compared with a calculation method without considering the influence of the relative acceleration, the collision time obtained through calculation is more timely in response and is closer to an ideal collision time value; meanwhile, the invention can also effectively reduce the influence of clutter, improve the calculation accuracy of collision time and further ensure the driving safety of the vehicle.
The embodiment of the present invention further provides a vehicle, which includes the above-mentioned device for calculating a collision time based on radar data, and is integrated in a controller of the vehicle, where the controller includes a processor and a memory, and the memory stores at least one instruction or at least one program, where the at least one instruction or the at least one program is loaded and executed by the processor to implement the method for calculating a collision time based on radar data; in yet another possible embodiment of the present description, the controller may be an autonomous driving range controller in a vehicle.
The processor (or CPU) is a core component of the device for calculating collision time based on radar data, and mainly has the functions of interpreting memory instructions and Processing data fed back by each monitoring module or acquisition module; the processor is generally divided into an arithmetic logic unit and a register unit, wherein the arithmetic logic unit mainly performs related logic calculations (such as shift operations, logic operations, fixed-point or floating-point arithmetic operations, address operations, etc.), and the register unit is used for temporarily storing instructions, data, and addresses.
The memory is a memory device and can be used for storing software programs and modules, and the processor executes various functional applications and data processing by running the software programs and modules stored in the memory. The memory can mainly comprise a program storage area and a data storage area, wherein the program storage area can store an operating system, application programs needed by functions and the like; the storage data area may store data created according to use of the device, and the like; accordingly, the memory may also include a memory controller to provide the processor access to the memory.
The embodiment of the present invention further provides a medium, where at least one instruction or at least one program is stored in the storage medium, and the at least one instruction or the at least one program is loaded and executed by a processor to implement the method for calculating collision time based on radar data; alternatively, the medium may reside on at least one of a plurality of network servers of a computer network; in addition, the medium may include, but is not limited to, various media that may store program codes, such as a Random Access Memory (RAM), a Read-Only Memory (ROM), a usb disk, a removable hard disk, a magnetic disk storage device, a flash Memory device, other volatile solid state storage devices, and the like.
It should be noted that the order of the above embodiments of the present invention is only for description, and does not represent the merits of the embodiments. And specific embodiments thereof have been described above. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims may be performed in a different order than in the embodiments and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing may also be possible or may be advantageous.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, as for the apparatus embodiment, since it is substantially similar to the method embodiment, the description is relatively simple, and for the relevant points, reference may be made to the partial description of the method embodiment.
While the invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes and modifications may be made, and equivalents may be substituted for elements thereof without departing from the scope of the invention as defined by the claims.
Claims (10)
1. A method for calculating a time to collision based on radar data, comprising:
establishing a quadratic equation of distance and time based on a kinematic formula of relative acceleration;
acquiring radar data monitored by a millimeter wave radar; the radar data at least comprises the relative distance between the vehicle and the front vehicle and the current time corresponding to the sampling relative distance;
estimating the coefficients of the quadratic equation according to the radar data and the estimation matrix to obtain a plurality of estimation coefficients of the quadratic equation;
calculating through the quadratic equation according to the estimation coefficient to obtain the prediction time when the relative distance is zero;
and carrying out collision prediction processing according to the current time and the predicted time to obtain collision time.
2. The method of claim 1, wherein the estimation matrix is a covariance matrix, and an initial value of the estimation matrix is an identity matrix.
3. The method of claim 1, wherein the estimating coefficients of the quadratic equation according to the radar data and an estimation matrix to obtain a plurality of estimation coefficients of the quadratic equation comprises:
performing preliminary estimation processing according to the radar data and the estimation matrix of the sampling point at the previous moment to obtain a weight factor of the current sampling point; wherein the sampling points correspond to the radar data one to one;
estimating according to the radar data, the weighting factor and the coefficient state of the sampling point at the previous moment to obtain the current coefficient state; wherein the coefficient state is composed of a plurality of the estimation coefficients.
4. The method of claim 1, wherein after the calculating according to the estimation coefficient and the quadratic equation to obtain the predicted time when the relative distance is zero, the method further comprises:
judging whether the predicted time is greater than the current time or not to select the value of the predicted time; wherein the number of the prediction time is two;
if the two predicted moments are both greater than the current moment, the predicted moment is the minimum value of the two predicted moments;
and if only one predicted time is greater than the current time, the predicted time is a value greater than the current time.
5. The method of claim 4, wherein after the calculating according to the estimation coefficient and the quadratic equation to obtain the predicted time when the relative distance is zero, the method further comprises:
judging whether the value of the predicted time is an imaginary number or not;
if the value of the predicted time is an imaginary number, setting the predicted time as a self-adaptive constant;
and if the value of the predicted time is not an imaginary number, executing the step of judging whether the predicted time is greater than the current time so as to select the value of the predicted time.
6. The method of claim 1, wherein the obtaining of the radar data monitored by the millimeter wave radar further comprises:
acquiring the radar data monitored by the millimeter wave radar within a preset time interval;
and translating the current moment according to the size of the preset time interval to obtain the translated current moment, and calculating the collision time in the preset time interval.
7. The method according to claim 6, wherein after the translating the current time according to the size of the preset time interval to obtain the translated current time, and calculating the collision time within the preset time interval, the method further comprises:
carrying out translation processing on the preset time interval;
and calculating the collision time in the translated preset time interval according to the coefficient state estimated from the previous preset time interval as an initial coefficient state.
8. A device for calculating a time-to-collision based on radar data, comprising at least:
the building module is used for building a quadratic equation of distance and time based on a kinematic formula of relative acceleration;
the acquisition module is used for acquiring radar data monitored by the millimeter wave radar; the radar data at least comprises the relative distance between the vehicle and the front vehicle and the current time corresponding to the sampling relative distance;
the estimation processing module is used for estimating the coefficients of the quadratic equation according to the radar data and the estimation matrix to obtain a plurality of estimation coefficients of the quadratic equation;
the calculation module is used for calculating through the quadratic equation according to the estimation coefficient to obtain the prediction time when the relative distance is zero;
and the collision prediction processing module is used for performing collision prediction processing according to the current time and the prediction time to obtain collision time.
9. A vehicle comprising the radar-data-based time-to-collision calculation apparatus of claim 8 integrated into a controller of the vehicle.
10. A medium having at least one instruction or at least one program stored therein, the at least one instruction or the at least one program being loaded and executed by a processor to implement the radar data based collision time calculation method according to any one of claims 1 to 7.
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