Vehicle control device and vehicle control method

Abstract

To contribute to safe driving by achieving vehicle speed control in consideration of cooperation with surrounding vehicles with a relatively simple and inexpensive configuration.SOLUTION: An average surrounding vehicle speed calculation unit configured to calculate an average surrounding vehicle speed based on an output of the detector, a first speed limit estimation unit configured to estimate a first speed limit based on the average surrounding vehicle speed, a second speed limit estimation unit configured to estimate a second speed limit based on an output of the detector or the average surrounding vehicle speed calculation unit, and a second reliability calculation unit configured to calculate a second reliability based on an output of the detector; A vehicle control device comprising: a speed limit and reliability selection unit configured to output a second reliability and a second speed limit when the second reliability is higher than the first reliability; and a control instruction unit configured to output a vehicle speed command corresponding to the speed limit received from the speed limit and reliability selection unit when the reliability received from the speed limit and reliability selection unit is equal to or higher than an arbitrary value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device and a vehicle control method that recognizes the speed limit of a travel section and controls the vehicle speed. [Background technology]

[0002] A known example of a device that controls vehicle speed in accordance with a recognized speed limit is the vehicle control device described in Patent Document 1. For example, claim 1 of this document states, "A vehicle control device including a plurality of speed limit recognition means for recognizing the speed limit in a section in which the vehicle is traveling, a braking / driving force output means for outputting driving force and braking force related to vehicle traveling, and a control means for controlling the vehicle, wherein the control means performs recognition-match control, in which, when a speed limit is recognized by two or more of the plurality of speed limit recognition means and the speed limits recognized by the two or more speed limit recognition means coincide, the control means controls the braking / driving force output means so that the vehicle travels at a speed equal to or less than the coincident speed limit." Claim 2 of this document states, "The vehicle control device is characterized in that, when the speed limit is recognized by only one of the plurality of speed limit recognition means, the control means performs independent recognition control, which is gentler than the recognition-match control."

[0003] In this way, Patent Document 1 discloses a vehicle control device that controls the vehicle speed so that it is below the agreed speed limit when the speed limits recognized by two or more speed limit recognition means are the same, and when only one speed limit recognition means recognizes the speed limit, performs gentler control than when the recognitions of two or more speed limit recognition means are the same. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-120111 Summary of the Invention [Problem to be solved by the invention]

[0005] However, as is clear from paragraph 0017 of Patent Document 1, which states that "the vehicle control device 1 includes, as its main components, a forward camera 10, a forward image recognition device 15, a rearward camera 20, a rearward image recognition device 25, a communication device 30, a navigation ECU (Electronic Control Unit) 35, a vehicle speed sensor 40, an HMI (Human Machine Interface) 50, and a master ECU 60," and paragraph 0024, which states that "the navigation ECU 35 is a computer unit that controls the navigation device, including a GPS receiver, a storage device storing map data, an LCD screen, an audio input / output device, an input switch unit, etc. When the communication device 30 acquires a speed limit, the navigation ECU 35 outputs the acquired speed limit to the master ECU 60." To realize the vehicle control device described in Patent Document 1, a camera and other devices requiring relatively advanced technology, such as a communication device, a GPS, and a high-precision map, are required. Therefore, installing the vehicle control device described in Patent Document 1 in a vehicle significantly increases the vehicle's manufacturing costs.

[0006] Furthermore, even if the technology in Patent Document 1 is used to switch vehicle speed control methods when there is a mismatch in the recognition of the speed limit, the switched vehicle speed control method does not take into account the speeds of surrounding vehicles, making it difficult to cooperate with surrounding vehicles.

[0007] The present invention is intended to solve these problems, and its main purpose is to realize vehicle speed control that takes into account cooperation with surrounding vehicles with a relatively simple and inexpensive configuration in a vehicle control device that recognizes speed limits and controls vehicle speed, thereby contributing to safe driving. [Means for solving the problem]

[0008] In order to solve the above problem, the vehicle control device of the present invention is a vehicle control device comprising: an average surrounding vehicle speed calculation unit that calculates an average surrounding vehicle speed, which is an average value of the vehicle speeds of surrounding vehicles, based on the output of a detector; a first speed limit estimation unit that estimates a first speed limit based on the average surrounding vehicle speed; a first reliability calculation unit that calculates a first reliability, which is the reliability of the first speed limit, based on the output of the detector or the average surrounding vehicle speed calculation unit; a second speed limit estimation unit that estimates a second speed limit based on the recognition of a sign that specifies the speed limit; a second reliability calculation unit that calculates a second reliability, which is the reliability of the second speed limit, based on the output of the detector; a speed limit / reliability selection unit that compares the first reliability with the second reliability, and outputs the first reliability and the first speed limit if the first reliability is higher, and outputs the second reliability and the second speed limit if the second reliability is higher; and a control instruction unit that outputs a vehicle speed command corresponding to the speed limit received from the speed limit / reliability selection unit if the reliability received from the speed limit / reliability selection unit is equal to or greater than a given value. [Effects of the Invention]

[0009] According to the present invention, a vehicle control device that recognizes speed limits and controls vehicle speed can achieve vehicle speed control that takes into account cooperation with surrounding vehicles with a relatively simple and inexpensive configuration, contributing to safe driving. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a functional block diagram of a vehicle control device according to an embodiment. [Figure 2] 10 is a time chart of vehicle speed control in a situation where the reliability of sign recognition is always high. [Figure 3] 10 is a time chart of vehicle speed control in a situation where the reliability of sign recognition is low. DETAILED DESCRIPTION OF THE INVENTION

[0011] A vehicle control device 1 according to an embodiment of the present invention will be described below with reference to the drawings.

[0012] 1 is a functional block diagram of a vehicle control device 1 according to this embodiment. This vehicle control device 1 is an ECU (Electronic Control Unit) that controls the drive system and braking system of the vehicle so that the vehicle speed is equal to or less than a predetermined speed limit by transmitting a speed command generated based on the output of a detector 2 to the drive system and braking system of the vehicle, and includes an average surrounding vehicle speed calculation unit 3, a first speed limit estimation unit 4, a speed change rate calculation unit 5, a first reliability calculation unit 6, a second speed limit estimation unit 7, a second reliability calculation unit 8, a speed limit / reliability selection unit 9, and a control instruction unit 10. Each component will be described in detail below.

[0013] The detector 2 is a group of sensors such as a camera 2a for reading road signs or road markings (hereinafter simply referred to as signs) that specify speed limits or the types of surrounding vehicles, a radar 2b for detecting the relative vehicle speed of surrounding vehicles, and a vehicle speed detector 2c for detecting the vehicle speed of the vehicle itself. The detector 2 transmits data required by the average surrounding vehicle speed calculation unit 3, the first reliability calculation unit 6, the second speed limit estimation unit 7, and the second reliability calculation unit 8, respectively.

[0014] The average surrounding vehicle speed calculation unit 3 calculates the average vehicle speed of surrounding vehicles such as preceding vehicles, vehicles running alongside, and oncoming vehicles based on the outputs of the radar 2b and the vehicle speed detector 2c, and outputs this as the average surrounding vehicle speed Va to the first speed limit estimation unit 4, the speed change rate calculation unit 5, and the first reliability calculation unit 6.

[0015] When the average surrounding vehicle speed calculation unit 3 calculates the average vehicle speed, it may exclude abnormal vehicle speeds that deviate from the standard deviation. Alternatively, it may estimate whether the speed limits on the uphill and downhill directions are the same based on factors such as the road slope, and only when it is estimated that the speed limits on both directions are the same (for example, when traveling on flat ground) may the average vehicle speed be calculated taking into account the speed of oncoming vehicles. Furthermore, it may estimate the type of surrounding vehicles based on the image data captured by camera 2a, and calculate the average vehicle speed by weighting public transportation such as buses and emergency vehicles such as police cars that are not in an emergency. Furthermore, when freight vehicles with different speed limits are traveling around the vehicle, it is desirable to calculate the average vehicle speed by excluding the speed of the freight vehicles.

[0016] The first speed limit estimation unit 4 estimates a first speed limit V1 in units of 10 km / h based on the average surrounding vehicle speed Va calculated by the average surrounding vehicle speed calculation unit 3, taking into consideration regional attributes, and transmits the first speed limit V1 to the speed limit / reliability selection unit 9. For example, in consideration of the fact that many vehicles in Japan exceed the speed limit, the first speed limit estimation unit 4 subtracts an arbitrary value (for example, 10 km / h) from the average surrounding vehicle speed Va, and sets the first speed limit V1 to that speed.

[0017] Based on the output of camera 2a or average surrounding vehicle speed calculation unit 3, first reliability calculation unit 6 calculates a first reliability T1 for the first speed limit V1 estimated by first speed limit estimation unit 4 and transmits the calculated reliability to speed limit / reliability selection unit 9. Note that because there is a high possibility that both the subject vehicle and other vehicles will be accelerating or decelerating for a certain period of time after sign recognition, first reliability calculation unit 6 sets the first reliability T1 low for the period immediately after sign recognition based on the image data captured by camera 2a. Also, if the number of vehicles used to calculate the average vehicle speed by average surrounding vehicle speed calculation unit 3 is equal to or less than a given value, first reliability calculation unit 6 considers the reliability of the calculated average vehicle speed to be low, and sets the first reliability T1 low for the entire time domain, regardless of the time since sign recognition.

[0018] The second speed limit estimation unit 7 estimates a second speed limit V2 based on the speed limit specified by the sign photographed by the camera 2a, and transmits it to the speed change rate calculation unit 5 and the speed limit / reliability selection unit 9.

[0019] The speed change rate calculation unit 5 calculates the rate of change between the average surrounding vehicle speed Va and the second speed limit V2 within a certain time period after passing the sign, and outputs the rate of change to the first reliability calculation unit 6. If the difference between the two change rates is equal to or less than a given value (in other words, if it can be determined that the surrounding vehicles are accelerating or decelerating in accordance with the speed limit indicated by the sign), the first reliability calculation unit 6 does not lower the first reliability T1 even if the number of surrounding vehicles used when the average surrounding vehicle speed calculation unit 3 calculates the average surrounding vehicle speed Va is equal to or less than the given value.

[0020] The second reliability calculation unit 8 calculates a second reliability T2 for the second speed limit V2 estimated by the second speed limit estimation unit 7 based on the image capture data from the camera 2a, and transmits the calculated second reliability T2 to the speed limit / reliability selection unit 9. The initial value of this second reliability T2 is set to a value (e.g., 90%) greater than the maximum value (e.g., 80%) of the first reliability T1 calculated by the first reliability calculation unit 6. If the camera 2a does not detect a subsequent sign even after a sufficient amount of time has passed since detecting a sign, it is highly likely that the sign was overlooked, and the second reliability calculation unit 8 sets the second reliability T2 to a low value (e.g., 10%). Furthermore, if the signal-to-noise ratio of the image capture data from the camera 2a is lower than a predetermined value due to the effects of rain, snow, lens dirt, or the like, the second reliability calculation unit 8 also sets the second reliability T2 to a low value.

[0021] The speed limit / reliability selection unit 9 selects and outputs the higher of the first reliability T1 and the second reliability T2 input from the first reliability calculation unit 6 and the second reliability calculation unit 8. When outputting the first reliability T1, the speed limit / reliability selection unit 9 selects and outputs the first speed limit V1, and when outputting the second reliability T2, it selects and outputs the second speed limit V2.

[0022] If the reliability received from the speed limit / reliability selection unit 9 is equal to or greater than a given value, the control instruction unit 10 outputs a deceleration command according to the speed limit received from the speed limit / reliability selection unit 9. On the other hand, if the reliability received from the speed limit / reliability selection unit 9 is less than the given value, the control instruction unit 10 continues to output the previous vehicle speed command.

[0023] Next, the vehicle speed control by the vehicle control device 1 of this embodiment will be specifically described with reference to the time charts of FIGS.

[0024] FIG. 2 is a time chart of vehicle speed control in a situation where the second reliability T2 of the second speed limit V2 based on sign recognition is always higher than the first reliability T1 of the first speed limit V1 based on the surrounding vehicle speeds.

[0025] 2(a) is a conceptual diagram showing the positional relationship between the vehicle and signs. As shown in the figure, signs specifying a speed limit of 60 km / h, a speed limit of 50 km / h, and a speed limit of 40 km / h are installed on the road on which the vehicle is traveling. Therefore, the vehicle control device 1 installed in the vehicle traveling on this road needs to sequentially output deceleration commands to decelerate the vehicle speed to 60 km / h, 50 km / h, and 40 km / h in that order.

[0026] In Fig. 2(b), the reliability indicated by the dashed line represents the second reliability T2, and the reliability indicated by the solid line represents the first reliability T1. Therefore, in Fig. 2, the second reliability T2 based on sign recognition is always higher than the first reliability T1 based on the surrounding vehicle speed.

[0027] In addition, the speed limit based on sign recognition in Figure 2(c) indicates the second speed limit V2 estimated by the second speed limit estimation unit 7, and the speed limit based on the average surrounding vehicle speed in Figure 2(d) indicates the first speed limit V1 estimated by the first speed limit estimation unit 4.

[0028] Figure 2 shows a case where there are no problems with sign recognition, so the second reliability T2 remains constant and high throughout the entire time domain. At times t1 and t2, camera 2a recognizes a sign ahead, but because the second reliability T2 is higher than the first reliability T1 at both times, the speed limit / reliability selection unit 9 outputs the second speed limit V2 corresponding to the second reliability T2 to the control instruction unit 10. Therefore, the control instruction unit 10 outputs a deceleration command to the braking system to follow the second speed limit V2 based on sign recognition, as shown in Figure 2(e).

[0029] In this example, the roadway had signs arranged so that the speed limits gradually decreased, so the control instruction unit 10 output a deceleration command to the braking system. However, if the signs had been arranged so that the speed limits gradually increased, it goes without saying that the control instruction unit 10 would output an acceleration control command to the drive system.

[0030] On the other hand, Figure 3 is a deceleration control time chart for a situation in which the second reliability T2 for the second speed limit V2 based on sign recognition is lower than the first reliability T1 for the first speed limit V1 based on the surrounding vehicle speed in some sections.

[0031] In this example, when a sign indicating a speed limit of 50 km / h is recognized at time t3, the second reliability T2 is higher than the first reliability T1, as in Figure 2, so the control instruction unit 10 outputs a deceleration command based on the second speed limit V2.

[0032] However, in this example, since sufficient time has passed since time t3, when camera 2a recognized the sign, the next sign cannot be detected, suggesting a high possibility that the sign was overlooked. Therefore, at time t4, second reliability calculation unit 8 sets second reliability T2 lower than first reliability T1. As a result, speed limit / reliability selection unit 9 outputs first reliability T1 and first speed limit V1 to control instruction unit 10 from time t4 onward. Therefore, control instruction unit 10 outputs a deceleration command to the braking system to achieve first speed limit V1, thereby achieving a vehicle speed that is coordinated with surrounding vehicles. Note that time t4 is a time when sufficient time has passed since camera 2a passed the sign that it overlooked, and therefore the surrounding vehicle speed is likely to have settled at a value close to the speed limit indicated by the sign. Therefore, with the above mechanism, even if camera 2a overlooks a sign, vehicle speed control in accordance with the correct speed limit can be achieved by referring to the speeds of surrounding vehicles.

[0033] As described above, the vehicle control device of this embodiment can realize vehicle speed control that takes into account cooperation with surrounding vehicles with a relatively simple and inexpensive configuration, thereby contributing to safe driving. [Explanation of symbols]

[0034] 1 vehicle control device, 2 detectors, 2a camera, 2b radar, 2c Vehicle speed detector, 3. Average surrounding vehicle speed calculation unit, 4. First speed limit estimation unit; 5. Speed ​​change rate calculation unit; 6. First reliability calculation unit; 7 second speed limit estimation unit, 8 second reliability calculation unit, 9 Speed ​​limit and reliability selection section, 10 Control instruction section

Claims

1. A vehicle control device that outputs a vehicle speed command based on an output of a detector, an average surrounding vehicle speed calculation unit that calculates an average surrounding vehicle speed, which is an average value of the vehicle speeds of surrounding vehicles, based on the output of the detector; a first speed limit estimation unit that estimates a first speed limit based on the average surrounding vehicle speed; a first reliability calculation unit that calculates a first reliability, which is a reliability of the first speed limit, based on an output of the detector or the average surrounding vehicle speed calculation unit; a second speed limit estimation unit that estimates a second speed limit based on recognition of a sign that specifies a speed limit; a second reliability calculation unit that calculates a second reliability, which is a reliability of the second speed limit, based on an output of the detector; a speed limit / reliability selection unit that compares the first reliability with the second reliability, and outputs the first reliability and the first speed limit if the first reliability is higher, and outputs the second reliability and the second speed limit if the second reliability is higher; a control instruction unit that outputs a vehicle speed command according to the speed limit received from the speed limit / reliability selection unit when the reliability received from the speed limit / reliability selection unit is equal to or greater than a predetermined value; A vehicle control device comprising:

2. The vehicle control device according to claim 1 , wherein the first speed limit estimation unit estimates a speed that is higher than the average surrounding vehicle speed by a predetermined speed as the first speed limit.

3. 2. The vehicle control device according to claim 1, wherein the first reliability calculation unit lowers the first reliability when the elapsed time since the detector detected the sign is equal to or less than a predetermined time, or when the number of surrounding vehicles used in calculating the average surrounding vehicle speed by the average surrounding vehicle speed calculation unit is equal to or less than a predetermined number.

4. a speed change rate calculation unit that calculates a change rate between the average surrounding vehicle speed and the second speed limit within a certain time period after passing the sign; 4. The vehicle control device according to claim 3, wherein the first reliability calculation unit does not lower the first reliability when the difference in the rate of change between the average surrounding vehicle speed and the second speed limit is equal to or less than an arbitrary value, even if the number of surrounding vehicles used in calculating the average surrounding vehicle speed by the average surrounding vehicle speed calculation unit is equal to or less than the predetermined number.

5. 2. The vehicle control device according to claim 1, wherein the second reliability calculation unit reduces the second reliability when a predetermined time has elapsed since the detector detected the sign, or when an S / N ratio of the data output by the detector is equal to or less than a predetermined value.

6. A vehicle control method for outputting a vehicle speed command based on an output of a detector, comprising: an average surrounding vehicle speed calculation step of calculating an average surrounding vehicle speed, which is an average value of the vehicle speeds of surrounding vehicles, based on the output of the detector; a first speed limit estimation step of estimating a first speed limit based on the average surrounding vehicle speed; a first reliability calculation step of calculating a first reliability that is the reliability of the first speed limit; a second speed limit estimation step of estimating a second speed limit based on recognition of a sign specifying a speed limit; a second reliability calculation step of calculating a second reliability that is the reliability of the second speed limit; a speed limit / reliability selection step of comparing the first reliability with the second reliability, and outputting the first reliability and the first speed limit if the first reliability is higher, and selecting the second reliability and the second speed limit if the second reliability is higher; a control instruction step of outputting a vehicle speed command according to the speed limit selected in the speed limit / reliability selection step when the reliability selected in the speed limit / reliability selection step is equal to or greater than a given value; A vehicle control method comprising:

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