Radar ranging method

Abstract

The present application belongs to the field of automobile electronics, and particularly relates to a radar ranging method, which determines the working state of the radar and the alarm interval according to the automobile communication system, the automobile communication system collects vehicle driving state information or automobile environment information, which is used to determine the working state of the radar, the working state of the radar includes a normal state and a high reaction state, each working state is provided with corresponding alarm interval information, then the radar collects obstacle information, compares the collected obstacle distance L with the alarm interval, and alarms according to the comparison result. The present application can dynamically adjust the alarm interval according to the vehicle driving state information or automobile environment information, and further select a more optimal working mode for the radar, so as to improve the accuracy of radar ranging and the reliability of the auxiliary driving function.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of automotive electronics, in particular to a radar ranging method. BACKGROUND

[0002] The reversing radar system can assist the user to determine the distance between the vehicle body and the obstacle, and has been popularly installed on various passenger cars. The radar ranging algorithm has been improved in accuracy after years of application and optimization, however, the frequent jump of critical distance still cannot be avoided.

[0003] Chinese patent CN104991246B discloses a radar ranging method for eliminating critical jitter, which compares the increased distance L1 with the critical distance value D. When the increased distance L1 does not belong to the value interval [D-5, D+5], the alarm and display are performed according to the L1 value itself; when the increased distance L1 is in the value interval [D-5, D+5], the previous cycle distance value L0 is compared, if the increased distance L1 is greater than the previous cycle distance value L0+5, the alarm is performed according to the value D-5, if the increased distance L1 is less than the previous cycle distance value L0-5, the alarm is performed according to the value D+5, and if the increased distance L1 is in the interval [L0-5, L0+5], the alarm is performed according to the increased distance L1 value itself.

[0004] The ultrasonic radar commonly used in parking assistance is easily affected by the weather, and the detection error is large when the vehicle speed is high. Even if the above method is applied to avoid the jump phenomenon, the ranging accuracy in different application scenarios cannot be guaranteed. SUMMARY

[0005] The purpose of the present application is to provide a radar ranging method which can weaken environmental errors and improve ranging accuracy.

[0006] To achieve the above purpose, the technical solution adopted by the present application is:

[0007] A radar ranging method,

[0008] Step one, judging the radar working state and determining the alarm interval according to the automobile communication system, the automobile communication system collects vehicle driving state information or automobile environment information, which is used to judge the radar working state;

[0009] Step two, the radar collects obstacle information, compares the collected obstacle distance L with the alarm interval, and alarms according to the comparison result; wherein, the radar working state includes a normal state and a high reaction state, each working state sets corresponding alarm interval information; in the same alarm interval, the interval range of the alarm interval in the high reaction state is smaller than that in the normal state.

[0010] Compared with the prior art, the present application has the following technical effects: the alarm interval can be dynamically adjusted according to the vehicle driving state information or the environment information of the vehicle, and a more optimal working mode is selected for the radar, thereby improving the accuracy of radar ranging and the reliability of the auxiliary driving function. BRIEF DESCRIPTION OF DRAWINGS

[0011] The content expressed by each drawing of the present specification and the labels in the drawings are briefly described as follows:

[0012] Figure 1 is a flowchart of the radar working in the normal state of example one;

[0013] Figure 2 is a flowchart of the radar working in the high reaction state of example one. DETAILED DESCRIPTION

[0014] The specific embodiments of the present application are further described in detail below through the description of examples.

[0015] Example one

[0016] A radar ranging method, comprising the following steps:

[0017] Step one, determining the radar working state and the alarm interval according to the vehicle communication system.

[0018] The ultrasonic radar is greatly affected by factors such as air humidity, temperature, transmission frequency, and the properties of the measured object. In order to ensure the accuracy of the measurement results, the vehicle communication system collects vehicle driving state information or environment information of the vehicle for determining the radar working state. The vehicle driving information includes the vehicle driving speed and the brake pedal stepping frequency, and the environment information of the vehicle includes the obstacle distance change rate, the ambient light intensity, and the radar probe temperature.

[0019] The radar working state includes a normal state and a high reaction state. In each working state, there are at least two alarm intervals. The prior art usually adopts a buzzer alarm, and the distance between the vehicle body and the obstacle is represented by the buzzer sound frequency. Generally, the higher the buzzer sound frequency, the smaller the distance between the vehicle and the obstacle.

[0020] In the high reaction working state, the sensitivity of the radar is higher. Therefore, in the same alarm interval, that is, in the alarm interval with the same buzzer sound frequency in different radar working states, the interval range of the alarm interval in the high reaction state is smaller than that in the normal state. For example, in the normal state, the interval range of the first alarm interval is [30, 100], and the interval range of the second alarm interval is [100, 150]; in the high reaction state, the interval range of the first alarm interval is [30, 70], and the interval range of the second alarm interval is [70, 100].

[0021] The improvement of radar ranging sensitivity makes false alarm or critical jitter phenomenon more likely to occur. The alarm interval information for distinguishing the high reaction state from the normal state makes the area range of the alarm interval in the high reaction state more reasonable, and effectively reduces the occurrence of critical jitter phenomenon.

[0022] In this embodiment, the vehicle speed is set as the radar working state judgment condition, and the radar working state is the normal state by default. The specific judgment method is that when the vehicle speed is greater than the threshold, the radar enters the high reaction state, otherwise the radar enters the normal state. Since the faster the vehicle speed, the faster the distance between the vehicle body and the surrounding obstacles changes, the high reaction state can detect obstacle information more quickly, thereby providing auxiliary judgment information for reversing in time.

[0023] In other embodiments, any one of the obstacle distance change rate, ambient light intensity, radar probe temperature, brake pedal depression frequency, or other related vehicle driving state information and environment information of the vehicle can be applied as the judgment condition of the radar working state.

[0024] If the vehicle speed is used as the judgment condition, when the vehicle speed is greater than the threshold, the radar enters the high reaction state, otherwise the radar enters the normal state;

[0025] If the obstacle distance change rate is used as the judgment condition, when the change rate of the obstacle distance collected by the radar is greater than the threshold, the radar enters the high reaction state, otherwise the radar enters the normal state;

[0026] If the ambient light intensity is used as the judgment condition, when the vehicle is in an environment with light intensity lower than the threshold, the radar enters the high reaction state, otherwise the radar enters the normal state;

[0027] If the radar probe temperature is used as the judgment condition, when the temperature of the vehicle is lower than the threshold or higher than the threshold, the radar enters the high reaction state, otherwise the radar enters the normal state; or when the temperature difference of each radar probe is greater than the set threshold, the radar enters the high reaction state, otherwise the radar enters the normal state;

[0028] If the brake pedal depression frequency is used as the judgment condition, when the depression frequency of the brake pedal is greater than the set threshold, the radar enters the high reaction state, otherwise the radar enters the normal state;

[0029] Step 2, the radar collects obstacle information, compares the collected obstacle distance L with the alarm interval, and alarms according to the comparison result.

[0030] In order to prevent the detection result from repeatedly jumping in the adjacent alarm interval, and to make the user difficult to judge the distance between the vehicle body and the obstacle, the interval range of the alarm interval in which the obstacle is located in the last period is enlarged, except for the first ranging period. If the obstacle distance L measured in the current period is similar to the critical value of the alarm interval in the last period, it is considered that the obstacle is still in the alarm interval in the last period, the jump caused by the similar obstacle distance L and the critical value is avoided, and the frequent change of the alarm signal is prevented.

[0031] That is, after the radar collects the obstacle distance L, the obstacle distance L is compared with the enlarged interval of the alarm interval in the last ranging period.

[0032] Let the critical value of the alarm interval in the last period be d 01 , d 02 ,

[0033] If d 01 -a≤L≤d 02 +a, the alarm is performed according to the result of the last period,

[0034] If L 01 -a or L > d 02 +a or the current period is the first ranging period, the obstacle distance L is compared with the original alarm interval to determine, and then the alarm is performed according to the determination result. Wherein a is a constant, and a 02 < d 01 / 2. In the specific implementation, the constant a can be set by the engineer according to experience, and a=2 in the embodiment. The value of a can also be related to the vehicle driving state information or the environment information of the vehicle. For example, the value of a is negatively related to the vehicle driving speed. The faster the vehicle driving speed, the faster the distance between the vehicle body and the obstacle changes, and the tolerance of the critical value of the alarm interval is reduced, which can avoid the reduction of accuracy caused by the lag of the change of the alarm interval. Similarly, the value of a is negatively related to the change rate of the obstacle distance. Of course, the more preferred solution is that the value of a is positively related when the vehicle is far away from the obstacle, and is negatively related when the vehicle is close to the obstacle. The value of a is negatively related to the frequency of stepping on the brake pedal. If the user frequently steps on the brake pedal, the vehicle may be in a more complex scene, and the tolerance of the critical value of the alarm interval is reduced, which can timely reflect the change of the distance between the vehicle body and the obstacle.

[0035] In the embodiment, the radar in the normal working state specifically includes the following steps:

[0036] a. The radar collects the obstacle distance L;

[0037] b. Determine whether it is the first ranging period. If yes, go to step e, otherwise go to step c;

[0038] c. increase the interval range of the alarm interval to which the current cycle belongs;

[0039] d. determine whether the obstacle distance L belongs to the alarm interval obtained in step c,

[0040] if yes, alarm according to the alarm interval to which the current cycle belongs, restore the interval range of the alarm interval to which the current cycle belongs, and then return to step a,

[0041] if no, restore the interval range of the alarm interval to which the current cycle belongs, and enter step e;

[0042] e. compare the obstacle distance L with each alarm interval, determine the alarm interval to which it belongs, and then alarm according to the determination result;

[0043] f. enter step a.

[0044] When the radar is in a high reaction state, the radar compares the obstacle distance L obtained after collection with the latest alarm interval information to determine, and then alarms according to the determination result. When the alarm interval to which the obstacle distance L belongs changes each time, the interval range of the changed alarm interval is reduced and the alarm interval information is updated until the interval range of the alarm interval is less than or equal to D, where D is a constant. That is, after the obstacle is determined to be in a certain alarm interval range for the first time, if the alarm interval jumps, the condition for determining that the obstacle returns to the alarm interval will change. The specific change of the determination condition is that the obstacle distance L should be in the new interval range after the range of the alarm interval is reduced. For example, the interval range of the first alarm interval is [30, 70], after the obstacle is determined to be in the first alarm interval for the first time, the obstacle is determined to be in another alarm interval, and when the obstacle is determined to be in the first alarm interval again, the obstacle distance L should be in the interval range [35, 65]. Then, the obstacle enters another alarm interval, and when the obstacle is determined to be in the first alarm interval for the third time, the obstacle distance L should be in the interval range [40, 60]. In this way, the alarm range can be maintained, and the false alarm of the radar in the high sensitivity detection mode can be avoided.

[0045] In the same alarm interval in this embodiment, the wave emission frequency in the high reaction state is higher than the wave emission frequency in the normal state. For example, in the normal state, the detection wave frequency of the first alarm interval is 3hz, and in the high reaction state, the detection wave frequency of the first alarm interval is 4hz. The higher the frequency of the detection wave, the higher the sensitivity, but the detection angle in the horizontal and vertical directions is smaller. That is, it is easier to detect obstacles in the high reaction state, and false alarms are more likely to occur. Therefore, in the high reaction state of the radar, the alarm interval is reduced to increase the difficulty of jumping to the alarm interval that has been entered, thereby achieving the effect of maintaining the same alarm interval.

[0046] To change the alarm interval range, after obtaining the obstacle distance L judgment result, it is necessary to determine whether the obstacle is in the same alarm interval as the previous cycle. If so, no change is needed to the alarm interval information, and the next ranging cycle can be directly entered. If not, the range of the alarm interval in the current cycle should be narrowed first, and the new alarm interval range should be updated to the alarm interval information before entering the next ranging cycle.

[0047] Each alarm interval has a minimum range D, which is 15cm in this embodiment. The reduction value of the alarm interval range and the minimum alarm interval range can be changed according to radar performance and actual application scenarios. Let the reduction value of the alarm interval range be 2b, where b is a constant; in this embodiment, b = 5. In other embodiments, the value of b can be different for different alarm intervals, or the reduction range of the alarm interval can be different each time.

[0048] It should be noted that b ≥ a under normal circumstances. This is because in normal working conditions, it is sufficient to meet the anti-shake requirement as long as the measured obstacle distance L does not jump when it is close to the critical value of the previous cycle. However, when the radar is in high-response working state, obstacles or vehicle bodies may move rapidly, or the environment around the vehicle body may be complex, which will greatly affect the radar's detection performance. The collected obstacle distance L will have a large deviation. Therefore, significantly narrowing the interval range can effectively avoid the alarm interval from jumping repeatedly, which will cause the alarm beep frequency to change frequently, thus providing users with reliable alarm information, while ensuring alarm accuracy.

[0049] In this embodiment, the radar is in a high-response state, specifically including the following steps:

[0050] a. Radar detects the distance L of the obstacle;

[0051] b. Compare the obstacle distance L with the new alarm interval information, determine the alarm interval to which it belongs, and then trigger an alarm.

[0052] c. Determine whether the current cycle and the previous cycle belong to the same alarm interval.

[0053] If so, proceed to step a.

[0054] If not, narrow the range of the alarm interval for this cycle, update the alarm interval information, and then proceed to step a.

[0055] In this way, the range of the alarm interval after the jump can be updated each time an alarm interval jump occurs.

[0056] Example 2

[0057] The difference between this embodiment and Embodiment 1 is that, in step one, two or more of the following are set as radar operating status judgment conditions: vehicle speed, obstacle distance change rate, ambient light intensity, radar probe temperature, brake pedal depressing frequency, and GPS positioning. The radar operating status is set to normal by default. When any one of the judgment conditions reaches the high-response state judgment threshold, the radar enters a high-response operating state.

[0058] For example, vehicle speed, brake pedal depressing frequency, and ambient light intensity can be selected as the conditions for determining the radar's operating status. When the vehicle speed exceeds a set threshold, or the brake pedal depressing frequency exceeds a set threshold, or the ambient light intensity is below a set threshold, the radar enters a high-response state; otherwise, the radar enters a normal state.

[0059] Example 3

[0060] The difference between this embodiment and embodiment two is that each judgment condition is calculated using reference coefficients. When the sum of the reference coefficients of each judgment condition reaches a set threshold, the radar enters a high-response working state. Among them, the proportions of vehicle speed and obstacle distance change rate are greater than the proportions of ambient light intensity, radar probe temperature, and brake pedal pressing frequency.

[0061] For example, the obstacle distance change rate, radar probe temperature, illuminance, brake pedal depressing frequency, and GPS positioning information are selected as judgment conditions. Among them, the obstacle distance change rate judgment result accounts for 50%, the radar probe temperature and illuminance judgment results account for 30%, the brake pedal depressing frequency judgment result accounts for 10%, and the GPS positioning information judgment result accounts for 10%. The radar operating status is judged according to the weight of each judgment condition. When the cumulative judgment result reaches the high-response state switching condition, the radar enters the high-response state.

Claims

1. A radar ranging method, comprising the following steps: Step 1: Determine the radar's operating status and alarm range based on the vehicle's communication system. The vehicle communication system collects information on the vehicle's driving status or the environment in which the vehicle is located, in order to determine the radar's working status. Step 2: The radar collects obstacle information, compares the collected obstacle distance L with the alarm range, and issues an alarm based on the comparison result; in, The radar operates in two states: normal and high-response. Each state has a corresponding alarm range. Within the same alarm range, the range of the alarm range in the high-response state is smaller than that in the normal state. When the radar is in normal operating condition, in step two, after the radar acquires the obstacle distance L, it first compares the obstacle distance L with the expanded range of the alarm interval of the previous ranging cycle, and records the critical value d of the alarm interval of the previous cycle. 01 d 02 If d 01 -a≤L≤d 02 +a, trigger an alarm based on the results of the previous cycle, if L < d 01 -a or L>d 02 +a or this cycle is the first ranging cycle. The obstacle distance L is compared with the original alarm interval information for judgment, and then an alarm is triggered according to the judgment result, where a is a constant and a < (d 02 -d 01 ) / 2; When the radar is in a high-response state, in step two, after the radar acquires the obstacle distance L, it compares the obstacle distance L with the latest alarm interval information and then issues an alarm according to the judgment result. Each time the alarm interval to which the obstacle distance L belongs changes, the range of the changed alarm interval is narrowed and the alarm interval information is updated until the range of the alarm interval is less than or equal to D, where D is a constant.

2. The radar ranging method according to claim 1, characterized in that: Within the same alarm range, the emission frequency under high-response conditions is higher than that under normal conditions.

3. The radar ranging method according to claim 1, characterized in that: When the radar is in normal operating condition, step two specifically includes the following steps. a. Radar detects the distance L of the obstacle; b. Determine if this is the first ranging cycle. If yes, proceed to step e; otherwise, proceed to step c. c. Increase the range of the alarm interval belonging to the previous cycle; d. Determine whether the obstacle distance L falls within the alarm range obtained in step c. If so, trigger an alarm according to the alarm interval of the previous cycle, restore the interval range of the alarm interval of the previous cycle, and then return to step a. If not, restore the range of the alarm interval to that of the previous cycle and proceed to step e; e. Compare the distance L of the obstacle with each alarm interval, determine the alarm interval to which it belongs, and then trigger an alarm. f. Proceed to step a.

4. The radar ranging method according to claim 1, characterized in that: When the radar is in a high-response state, step two specifically includes the following steps. a. Radar detects the distance L of the obstacle; b. Compare the distance L of the obstacle with each alarm interval, determine the alarm interval to which it belongs, and then trigger an alarm. c. Determine whether the current cycle and the previous cycle belong to the same alarm interval. If so, proceed to step a. If not, narrow the range of the alarm interval to which this cycle belongs, update the alarm interval information, and then proceed to step a; The alarm interval has a range of 15cm or more.

5. The radar ranging method according to claim 4, characterized in that: In step c, the range of the alarm interval is reduced by 2b, where b is a constant and b ≥ a.

6. The radar ranging method according to claim 1, characterized in that: In step one, any one of the following is set as the radar working status judgment condition: vehicle speed, obstacle distance change rate, ambient light intensity, radar probe temperature, and brake pedal depressing frequency. The radar's default operating state is normal. If the vehicle speed is used as the judgment condition, the radar enters a high-response state when the vehicle speed is greater than the threshold, otherwise the radar enters a normal state. If the rate of change of obstacle distance is used as the criterion, when the rate of change of obstacle distance acquired by the radar is greater than the threshold, the radar enters a high-response state; otherwise, the radar enters a normal state. If ambient light intensity is used as the criterion, the radar enters a high-response state when the vehicle is in an area where the light intensity is below the threshold; otherwise, the radar enters a normal state. If the radar probe temperature is used as the judgment condition, when the temperature of the vehicle is below or above the threshold, or when the temperature difference between the radar probes is greater than the set threshold, the radar enters a high-response state; otherwise, the radar enters a normal state. If the frequency of brake pedal application is used as the judgment condition, the radar enters a high-response state when the frequency of brake pedal application exceeds a set threshold; otherwise, the radar enters a normal state.

7. The radar ranging method according to claim 1, characterized in that: In step one, two or more of the following are set as conditions for judging the radar's working status: vehicle speed, rate of change of obstacle distance, ambient light intensity, radar probe temperature, and brake pedal depressing frequency. The radar's default operating state is normal. The radar enters a high-response state when any one of the criteria reaches the high-response threshold. Alternatively, each judgment condition can be calculated using reference coefficients. When the sum of the reference coefficients of each judgment condition reaches a set threshold, the radar enters a high-response working state. Among these, the proportions of vehicle speed and obstacle distance change rate are greater than the proportions of ambient light intensity, radar probe temperature, and brake pedal tapping frequency.

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