JP5263041B2 - Road surface information acquisition device - Google Patents

Description

  The present invention relates to a road surface information acquisition device that acquires road surface information related to a road surface on which a vehicle or the like travels.

  In recent years, a technique has been developed in which an optimal travel locus of a vehicle is generated and the vehicle is automatically traveled using the travel locus. In this type of technology, it is required to acquire road surface information of a road surface on which the vehicle travels in addition to the traveling state of the vehicle. The road surface information here includes, for example, a road friction coefficient. As for the friction coefficient of the road surface, although various values are taken on an actual road surface, a constant estimated value is often used.

  Further, as a device for acquiring a friction coefficient of a road surface, there is a road surface information distribution system disclosed in Japanese Patent Application Laid-Open No. 2002-8198, for example. This road surface information distribution system detects road slip information while the vehicle is running, detects position information of the running vehicle, and aggregates the road slip information corresponding to the position of the vehicle. is there. The aggregated information is also distributed to other vehicles, and information related to road surface slipperiness corresponding to the position information is shared by a plurality of vehicles.

Japanese Patent Laid-Open No. 2002-8198

  By the way, when acquiring the friction coefficient, by acquiring the limit value of the friction coefficient, it is possible to perform control according to various situations. However, in the road surface information distribution system in Patent Document 1, it is difficult to acquire the limit value of the friction coefficient while the vehicle is traveling. For this reason, there is a problem that the situation where the information acquired by the road surface information distribution system can be used is limited.

  Then, the subject of this invention is providing the road surface information acquisition apparatus which can utilize the acquired road surface information effectively in various situations.

  A road surface information acquisition device according to the present invention that has solved the above problems acquires road surface information acquisition means that acquires, as road surface information, a friction coefficient of a road surface on which the vehicle travels, based on the vehicle state of the vehicle, and acquires the travel position of the vehicle. A road surface information acquisition device comprising: a travel position acquisition unit; and a road surface information recording unit that records the road surface information acquired by the road surface information acquisition unit in association with the travel position of the vehicle acquired by the travel position acquisition unit, The vehicle is further provided with grip state determination means for determining whether the vehicle is in a grip state or a non-grip state with respect to the road surface, and the road surface information recording means performs the distinction according to the determination result by the grip state determination means, It is characterized by recording information.

  The road surface information acquisition device according to the present invention further includes grip state determination means for determining whether the vehicle is in the grip state or the non-grip state, and the road surface information recording means is distinguished according to the determination result by the grip state determination means. To record road surface information. A certain reliable value can be obtained as the friction coefficient of the road surface in the grip state, but since the tire is slipping on the road surface in the non-grip state, the friction coefficient obtained here is the friction coefficient of the road surface. There is a high possibility that it is not reflected accurately. For this reason, by distinguishing according to the determination result by a grip state determination means, and recording road surface information, the acquired road surface information can be used effectively in various situations.

  Here, it can be set as the aspect which records the road surface information at the time of determining with a grip state as a lower limit friction coefficient.

  When the friction coefficient is acquired in the grip state, it can be expected that a friction coefficient higher than the acquired friction coefficient can be obtained. For this reason, by recording the road surface information in the grip state as the lower limit friction coefficient, it is possible to obtain the minimum value of the friction coefficient of the road surface obtained at the minimum.

  Moreover, it can be set as the aspect which records the road surface information acquired immediately before it determines with a non-grip state as an upper limit friction coefficient.

  It is unlikely that the friction coefficient exceeds the friction coefficient acquired immediately before the non-grip state is reached. For this reason, the limit value of the friction coefficient of a road surface is acquirable by recording the road surface information acquired immediately before it determines with a non-grip state as an upper limit friction coefficient.

  Furthermore, it can be set as the aspect further provided with the friction coefficient map production | generation means which produces | generates the friction coefficient map corresponding to the driving | running route of a vehicle based on the road surface information recorded by the road surface information recording means.

  Thus, by generating the friction coefficient map corresponding to the travel route of the vehicle based on the road surface information recorded by the road surface information recording means, it is possible to accurately generate the road surface information when performing the travel control of the vehicle. Can do. As a result, it is possible to perform appropriate travel control according to the road surface condition.

  According to the road surface information acquisition apparatus according to the present invention, the acquired road surface information can be effectively used in various situations.

It is a block block diagram of a travel control apparatus provided with a road surface information acquisition apparatus. It is a flowchart which shows the process sequence in a road surface condition acquisition part. It is a flowchart explaining the production | generation procedure of mu distribution map, and control amount calculation. It is explanatory drawing which shows the example of telematics information collection.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. For the convenience of illustration, the dimensional ratios in the drawings do not necessarily match those described.

  FIG. 1 is a block configuration diagram of a travel control device including a road surface information acquisition device according to the present embodiment. As shown in FIG. 1, the travel control apparatus according to this embodiment includes a travel control ECU (Electronic Control Unit) 1. The travel control ECU 1 is composed of a microcomputer having, as hardware, a ROM (Read Only Memory), a RAM (Random Access Memory) that temporarily stores input data, a CPU (Central Processing Unit) that executes a program, and the like. .

  The travel control ECU 1 includes a road surface condition acquisition unit 2, a friction coefficient map generation unit 3, and a control amount calculation unit 4. The road surface condition acquisition unit 2 includes a grip state determination unit 11, a friction coefficient calculation unit 12, a travel position acquisition unit 13, a road surface information recording unit 14, and a road surface information storage unit 15.

  Further, a brake pedal sensor 21, an accelerator pedal sensor 22, a rudder angle sensor 23, and a G sensor 24 are connected to the travel control ECU 1. The travel control ECU 1 includes a yaw rate sensor 25, a wheel speed sensor 26, a lane recognition sensor 27, a navigation system 28, a VSC (Vehicle Stability Control) ECU 29A, an ABS (Antilock Brake System) ECU 29B, and a TRC (Traction Control) ECU 29C. It is connected. Further, a throttle actuator 31, a brake actuator 32, and a steering actuator 33 are connected to the travel control ECU 1.

  The brake pedal sensor 21 detects the amount of depression of the brake pedal that is depressed by the driver. The amount of depression of the brake pedal detected here is detected by the brake pedal stroke or the depression force. The brake pedal sensor 21 transmits the detected brake pedal depression amount, which is the detected depression amount of the brake pedal, to the travel control ECU 1.

  The accelerator pedal sensor 22 detects the amount by which the accelerator pedal is depressed by the driver. The amount of depression of the accelerator pedal detected here is detected by the accelerator opening. The accelerator pedal sensor 22 transmits the accelerator pedal depression amount, which is the detected depression amount of the accelerator pedal, to the travel control ECU 1.

  The steering angle sensor 23 is attached to a steering rod of a vehicle, for example, and detects a steering angle of a steering wheel steered by a driver. The steering angle sensor 23 transmits the detected steering angle of the steering wheel to the travel control ECU 1.

  The G (acceleration) sensor 24 detects longitudinal acceleration and lateral acceleration acting on the vehicle. The G sensor 24 transmits the detected longitudinal acceleration and lateral acceleration to the travel control ECU 1. The yaw rate sensor 25 detects the yaw rate (lateral turning speed) generated in the vehicle. The yaw rate sensor 25 transmits the detected yaw rate to the travel control ECU 1.

  The wheel speed sensor 26 is provided for each of the four wheels of the vehicle, and detects the wheel speed of each wheel. The wheel speed sensor 26 transmits the detected wheel speed of each wheel to the travel control ECU 1. The travel control ECU 1 calculates the vehicle speed based on the transmitted wheel speed of each wheel.

  The lane recognition sensor 27 includes a camera and an image processing device, recognizes the left and right white lines on both sides of the travel lane, and recognizes the travel lane in which the vehicle travels. The lane recognition sensor 27 subjects the image captured by the camera to image processing by the image processing device, and transmits the detected positions (coordinates) of the left and right white lines to the travel control ECU 1. The travel control ECU 1 calculates a center line that is a line passing through the center of the vehicle from the transmitted left and right white line positions, a curve radius of the center line, and the like.

  The navigation system 28 is a system that detects the current position of the vehicle and provides route guidance to the destination. In particular, the navigation system 28 reads the road shape of the road on which the host vehicle is currently traveling from the map database, and transmits the read road shape to the travel control ECU 1. Further, the navigation system 28 transmits the travel position where the host vehicle is currently traveling to the travel control ECU 1.

  The VSC ECU 29A automatically detects the brake and engine output of each wheel when the sensor senses a sudden spin handle for avoiding an obstacle or a vehicle spin state that occurs when the vehicle slips on a slippery road surface. By controlling the speed, the unstable behavior of the host vehicle is suppressed. Further, the VSC ECU 29A transmits a non-grip state signal to the travel control ECU 1 when detecting the vehicle spin state.

  The ABS ECU 29B detects the slip of the tire when braking the host vehicle, and when the brake is in a brake lock state in which the slip of the tire occurs, the ABS ECU 29B performs a control to be a so-called pumping brake that repeats the operation of releasing the brake a little and then depressing it again. Is going. Further, the ABS ECU 29B transmits a non-grip state signal to the travel control ECU 1 when detecting the brake lock state.

  The TRC ECU 29C grasps the wheel spin state in which the tire idles from the vehicle speed and the rotation speed of each tire, and performs control to eliminate the wheel spin state by reducing the driving force from the engine. Further, the TRC ECU 29C transmits a non-grip state signal to the travel control ECU 1 when detecting the wheel spin state.

  The grip state determination unit 11 in the road surface condition acquisition unit 2 of the travel control ECU 1 determines the grip state of the host vehicle based on the non-grip state signal transmitted from the VSC ECU 29A, ABS ECU 29B, and TRC ECU 29C. The grip state determination unit 11 determines that the host vehicle is in the grip state when the non-grip signal is not transmitted from the VSC ECU 29A, ABS ECU 29B, or TRC ECU 29C, and if the non-grip signal is transmitted, It is determined that the vehicle is in the grip state. When it is determined that the host vehicle is in the non-grip state, the grip state determination unit 11 outputs a non-grip state signal to the friction coefficient calculation unit 12.

  The friction coefficient calculation unit 12 calculates the vehicle speed of the host vehicle based on the wheel speed transmitted from the wheel speed sensor 26. The lateral force applied to the host vehicle is calculated based on the calculated vehicle speed and the curve R obtained from the map shape transmitted from the navigation system 28. The friction coefficient calculation unit 12 calculates the friction coefficient of the road surface based on the calculated lateral force and the vehicle acceleration / deceleration transmitted from the G sensor 24. Further, when the non-grip state signal is output from the grip state determination unit 11, the friction coefficient calculation unit 12 does not calculate the friction coefficient, and calculates the previously calculated friction coefficient as the current friction coefficient. The friction coefficient calculation unit 12 outputs the calculated friction coefficient to the road surface information recording unit 14.

  The travel position acquisition unit 13 acquires the travel position of the host vehicle based on the travel position transmitted from the navigation system 28. The travel position acquisition unit 13 outputs the acquired travel position to the road surface information recording unit 14.

  The road surface information recording unit 14 records the friction coefficient output from the friction coefficient calculation unit 12 and the travel position output from the travel position acquisition unit 13 in the road surface information storage unit 15 as road surface information. The road surface information recorded in the road surface information storage unit 15 is associated with a travel position and a friction coefficient at the travel position. Further, in the road surface information recording unit 14, the friction coefficient calculated by the friction coefficient calculation unit 12 is a friction coefficient calculated by receiving a non-grip state signal or a friction coefficient calculated without receiving a non-grip state signal. The road surface information is recorded by distinguishing whether there is any.

  The road surface information storage unit 15 stores road surface information recorded by the road surface information recording unit 14. The road surface information storage unit 15 stores the friction coefficient in association with the road position, and when new road surface information is output for the same road position, it is rewritten and stored with a new friction coefficient.

  The friction coefficient map generation unit 3 extracts the road surface information stored in the road surface information storage unit 15 in the road surface condition acquisition unit 2, writes the friction coefficient in the map information stored in advance, and generates a friction coefficient map. The friction coefficient map generation unit 3 outputs the generated friction coefficient map to the control amount calculation unit 4.

  Based on the friction coefficient map output from the friction coefficient map generation unit 3 and various information transmitted from the various sensors 21 to 27, the control amount calculation unit 4 determines the control amount related to acceleration / deceleration and steering angle of the host vehicle. calculate. The control amount calculation unit 4 controls the throttle actuator 31, the brake actuator 32, and the steering actuator 33 according to the calculated control amount.

  The throttle actuator 31 opens and closes the throttle valve in the electronic throttle device and adjusts the throttle opening. The travel control ECU 1 operates the throttle actuator 31 by transmitting an engine control signal, adjusts the opening of the throttle valve, and adjusts the driving amount.

  The brake actuator 32 adjusts the control hydraulic pressure to the wheel cylinder provided in the brake device. The traveling control ECU 1 operates the brake actuator 32 by transmitting a brake control signal, adjusts the brake pressure of the wheel cylinder, and adjusts the braking amount.

  The steering actuator 33 applies a rotational driving force from the motor as a steering torque to the steering mechanism. The steering actuator 33 applies a rotational driving force to the steering mechanism via the speed reduction mechanism. The traveling control ECU 1 operates the steering actuator 33 by transmitting a steering control signal to the steering actuator 33, and adjusts the steering torque by the motor.

  In the travel control device according to the present embodiment, when performing manual travel or automatic travel, a travel line on which the vehicle travels is generated by a predetermined method, and road surface information on the road on which the vehicle travels is acquired. Using the road surface information acquired here, a μ distribution map for the generated travel line is generated. The travel control apparatus according to the present embodiment performs vehicle travel control based on the travel line and the μ distribution map thus generated.

  The generation of the travel line can be performed using a known method as appropriate. For example, when the road is generated with a clothoid curve, the line on which the vehicle travels in the center can be used as the travel line, or the line corrected using an optimization method can be used as the travel line. You can also.

  Next, the process procedure of the road surface condition acquisition unit in the travel control apparatus according to the present embodiment will be described. FIG. 2 is a flowchart illustrating a processing procedure in the road surface condition acquisition unit. As shown in FIG. 2, in the travel control apparatus according to this embodiment, first, it is determined whether or not the host vehicle is traveling (S1). This determination is made based on the vehicle speed calculated from the wheel speed transmitted from the wheel speed sensor 26. As a result, when it is determined that the host vehicle is not running, the processing is terminated as it is.

  On the other hand, if it is determined that the host vehicle is traveling, the lateral force of the host vehicle is calculated (S2). Here, the lateral force Ay of the host vehicle is calculated based on the following equation (1) using the vehicle speed V of the host vehicle and the curve radius R of the road on which the host vehicle travels.

Ay = V2 ^{/ R} (1)

  Next, the grip state determination unit 11 determines whether the host vehicle is in a grip state or a non-grip state (S3). The grip state determination unit 11 determines whether the grip state is in the grip state or the non-grip state based on whether a non-grip signal is transmitted from the VSC ECU 29A, ABS ECU 29B, or TRC ECU 29C. Here, when a non-grip signal is transmitted from any of the ECUs 29A to 29C, it is determined that the ECU is not in a grip state. When no non-grip signal is transmitted from any of the ECUs 29A to 29C, the grip is Judged as a state.

  If it is determined that the vehicle is in the grip state as a result of determining whether the vehicle is in the grip state or the non-grip state, the friction coefficient calculation unit 12 uses the following equation (2) to determine the lower limit in consideration of the acceleration / deceleration Ax of the vehicle. μ is calculated by calculation (S4). Further, the friction coefficient calculation unit 12 temporarily stores the lower limit μ calculated by the calculation until the next calculation is performed. Here, the lower limit μ is a lower limit value that a higher μ can be expected as μ on the road surface.

(Lower limit μ) = (Ax ² + Ay ² ) ^1/2 / g (2)

  When the lower limit μ is calculated, the road surface information recording unit 14 stores the lower limit μ as data in the road surface information storage unit 15 (S5). In storing the data, the road surface information recording unit 14 records the lower limit μ in the road surface information storage unit 15 as road surface information in association with the travel position of the host vehicle acquired by the travel position acquisition unit 13. Here, latitude and longitude are recorded as the traveling position of the host vehicle. It also records information such as temperature. In this way, the process in the road surface condition acquisition part 2 is complete | finished.

  On the other hand, if it is determined in step S3 that the host vehicle is in a non-grip state, the friction coefficient calculation unit 12 does not calculate the friction coefficient, and calculates the lower limit μ calculated by the previous calculation as the upper limit μ ( S6). Then, the road surface information recording unit 14 stores the upper limit μ as data in the road surface information storage unit 15 (S5). In this way, the process in the road surface condition acquisition part 2 is complete | finished.

  After acquiring the road surface information in the road surface condition acquisition unit 2 in this way, the friction coefficient map generation unit 3 creates a μ distribution map of the travel line based on the road surface information acquired by the road surface state acquisition unit 2. Further, the control amount calculation unit 4 uses the μ distribution map generated by the friction coefficient map generation unit 3 to calculate a control amount such as a speed pattern of the vehicle when traveling on the travel line.

  When creating a μ distribution map, the driving line is divided into a set of minute intervals and considered as a collection of multiple target points, and a friction coefficient map (hereinafter referred to as “μ distribution map”) for each of these target points is mapped. Turn into. Hereinafter, a procedure for creating a μ distribution map and calculating a control amount using the μ distribution map will be described. FIG. 3 is a flowchart for explaining the processing procedure for generating the μ distribution map and calculating the control amount.

  As shown in FIG. 3, the friction coefficient map generation unit 3 sets the first target point when setting μ at the target point on the travel line (S10). An arbitrary point on the travel line is set as the first target point here. Next, an upper limit μ within a predetermined temperature difference and within a predetermined range as viewed from the target point is searched from the road surface information stored in the road surface information storage unit 15 (S11). Here, the predetermined temperature difference refers to a range in which the temperature difference between the temperature at the time when the road surface information is acquired and the current temperature is within 5 ° C. Further, the predetermined range refers to a range within a radius of 10 m from the target point.

  As a result of searching for the upper limit μ within the predetermined temperature difference and within the predetermined range (S12), when the upper limit μ within the predetermined temperature difference and within the predetermined range is searched, the searched upper limit μ is set in the friction coefficient map. (S28). Here, when a plurality of upper limits μ satisfying this condition are found, the upper limit μ of the point closest to the target point is set in the friction coefficient map.

  However, the upper limit μ that satisfies other arbitrary conditions can be set. As an arbitrary condition at this time, for example, it is possible to set the upper limit μ of the point where the temperature difference at the target point is closest to the temperature difference. Alternatively, it may be an average value of the upper limit μ at a plurality of points, or a numerical value obtained by weighting a plurality of points using a coefficient corresponding to the relationship between the temperature difference and the distance.

  Further, when the upper limit μ within the predetermined temperature difference and the predetermined range is not searched, the lower limit μ within the predetermined temperature difference and the predetermined range is searched from the road surface information stored in the road surface information storage unit 15. (S13). As a result (S14), when the lower limit μ is searched, a predetermined coefficient, for example, 1.1 is added to the searched lower limit μ (S15) to calculate the correction lower limit μ, and the obtained correction lower limit μ is obtained. Is set in the friction coefficient map (S28). Here, when a plurality of lower limits μ satisfying this condition are searched, the lower limit μ of the point closest to the target point is set in the friction coefficient map. However, an arbitrary condition similar to that when the upper limit μ is set is set. It is also possible to set a lower limit μ that is satisfied.

  On the other hand, when the lower limit μ within the predetermined temperature difference and the predetermined range is not searched, the upper limit μ within the predetermined range is searched from the road surface information stored in the road surface information storage unit 15 regardless of the temperature difference. (S16). As a result (S17), if the upper limit μ within the predetermined range is found, the process proceeds to step S24.

  Further, when the upper limit μ within the predetermined range is not searched, the lower limit μ within the predetermined range is searched from the road surface information stored in the road surface information storage unit 15 regardless of the temperature difference (S18). As a result (S19), when the lower limit μ within the predetermined range is found, a predetermined coefficient, for example, 1.1 is added (S20), and the process proceeds to step S24.

  On the other hand, if the lower limit μ within the predetermined range is not retrieved, the temporary μ that is the temporary μ is set as the friction coefficient at the target point (S21). As the temporary μ here, a general numerical value, for example, 0.6 is used. However, other numerical values can be used. After setting the provisional μ, it is determined whether or not there is an altitude object whose temperature is low and whose elevation angle is 30 ° or more on the north side of the altitude of the target point (S22). The reference | standard of whether the temperature here is low can be 4 degreeC. Further, when it is not possible to obtain information on the altitude object, it is determined that there is no altitude object.

  As a result, if it is determined that there is an altitude object whose temperature is low and the elevation angle is 30 ° or more on the north side of the altitude of the target point, the provisional μ is corrected low (S23), and the corrected μ is calculated and calculated. The corrected μ is set in the friction coefficient map (S28). On the other hand, if it is determined that the condition that there is an altitude object having an elevation angle of 30 ° or more on the north side of the altitude of the target point, provisional μ is set in the friction coefficient map (S28).

  If it is determined in step S17 that the upper limit μ is within the predetermined range, and if it is determined in step S19 that the lower limit μ is within the predetermined range and the coefficients are integrated, the temperature at the time when the road surface information is acquired is low. If not (high), it is determined whether the current temperature is low (S24). The determination as to whether the temperature at the time when the road surface information is acquired is not low is performed based on, for example, 10 ° C. In addition, the determination as to whether or not the temperature at the current time is low is made based on 4 ° C., for example.

  As a result, when it is determined that the temperature at the time when the road surface information is acquired is not low and the current temperature is low, the coefficient is integrated in step S15 selected in step S11 or the upper limit μ selected in step S11. The correction lower limit μ is corrected to be low (S25). When the upper limit μ or the correction lower limit μ is corrected, for example, the upper limit μ or the correction lower limit μ is multiplied by 0.5 to halve these numerical values. If it is determined in step S24 that the temperature at the time when the road surface information is acquired is not low and the current temperature is low, the process directly proceeds to step S26.

  Thereafter, it is determined whether or not the temperature at the time when the road surface information is acquired is low and the current temperature is not low (high) (S26). The determination as to whether or not the temperature at the time when the road surface information is acquired is made based on 4 ° C., for example. In addition, whether or not the current temperature is not low (high) is determined based on 10 ° C., for example.

  As a result, when it is determined that the temperature at the time when the road surface information is acquired is low and the current temperature is not low, the coefficient is integrated in step S15 selected in step S11 or the upper limit μ selected in step S11. The correction lower limit μ is corrected to be higher (S27). When the upper limit μ or the correction lower limit μ is corrected, for example, the upper limit μ or the correction lower limit μ is multiplied by 1.2. In Step S26, if it is determined that the condition that the temperature at the time when the road surface information is acquired is low and the current temperature is not low is satisfied, the process directly proceeds to Step S28.

  Thereafter, the upper limit μ or the lower limit μ corrected or not corrected is set in the friction coefficient map (S28). After setting the friction coefficient map, it is determined whether or not the setting of the friction coefficient has been completed for all target points set on the travel line (S29). As a result, when it is determined that the setting of the friction coefficient for all target points has not been completed, the target point is shifted to the next target point (S30), and the process returns to step S11.

  On the other hand, if it is determined that the setting of the friction coefficients for all target points has been completed, the control amount calculation unit 4 calculates the vehicle speed pattern in consideration of the travel line and the friction coefficient in the travel line (S31). The speed pattern is calculated by the following procedure, for example. First, R is calculated for each target point obtained by dividing the travel line, and the maximum steady-state circle at each target point is calculated based on μ and R of each target point based on the μ distribution map generated by the friction coefficient map generation unit 3. Generate a velocity pattern.

  Thereafter, the acceleration between adjacent points is calculated from the travel start point toward the travel end point. If the acceleration is in excess of the acceleration, the speed at the high speed point is corrected to be within the acceleration upper limit. Further, the deceleration between adjacent points is calculated from the travel end point toward the travel start point, and if there is an excess of deceleration, the speed at the point with the higher speed is corrected to be within the deceleration upper limit. In this way, the speed pattern is calculated.

  After calculating the speed pattern, the control amount calculation unit 4 calculates a travel pattern related to acceleration / deceleration and steering angle of the host vehicle based on the calculated speed pattern and various information transmitted from the various sensors 21 to 27. A control amount to be realized is calculated. Then, the control amount calculation unit 4 controls the throttle actuator 31, the brake actuator 32, and the steering actuator 33 according to the calculated control amount. In this way, the process by the traveling control device is finished.

  Thus, in the travel control apparatus according to the present embodiment, the road surface condition acquisition unit 2 records the friction coefficient corresponding to the position of the road surface. Here, when the friction coefficient is acquired, road surface information is distinguished and recorded depending on whether the vehicle is in a grip state or a non-grip state. Specifically, for the friction coefficient obtained when the vehicle is in the grip state, the road surface information is recorded as the lower limit μ, and for the friction coefficient obtained when the vehicle is in the non-grip state, the road surface information is recorded as the upper limit μ. As recorded.

  When the vehicle is in a grip state, a friction coefficient greater than or equal to the friction coefficient obtained here can be obtained. For this reason, the coefficient of friction acquired when in the grip state is recorded as the lower limit μ. On the other hand, when the vehicle is in a non-grip state, the friction coefficient acquired here cannot be used, and it is unlikely that the friction coefficient acquired immediately before the acquisition is higher than the friction coefficient. For this reason, the coefficient of friction acquired when in the non-grip state is recorded as the upper limit μ. In this manner, by recording the road surface information by distinguishing it according to the state when the friction coefficient is acquired, the acquired road surface information can be effectively used in various situations.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. For example, in the above embodiment, the road surface information storage unit 15 is provided in the vehicle, but may be provided in a computer in a telematics information center (hereinafter referred to as “information center”), for example. In this aspect, the vehicle includes a transmission / reception device capable of transmitting / receiving to / from the information center, and the road surface information recording unit 14 applies a friction coefficient to the road surface information storage unit provided in the information center via the transmission / reception device. Record. According to this aspect, road surface information acquired not only by the host vehicle but also by other vehicles such as a probe car can be used, and information acquired by a plurality of vehicles can be shared among the plurality of vehicles.

  For example, as shown in FIG. 4, the road surface information of the road R is acquired by the first probe car P1 and the second probe car P2, transmitted to the computer C, and the host vehicle M receives the road surface information from the computer C. Suppose. At this time, the probe cars P1 and P2 and the host vehicle M are equipped with a travel control device including the transmission / reception device described above.

  For example, when the first probe car P1 acquires the friction coefficient at the measurement point Ra on the road R, the first probe car P1 transmits road surface information regarding the measurement point Ra including the acquired friction coefficient to the computer C in the information center via the transmission / reception device. To do. The road surface information transmitted by the first probe car P1 is given information such as the latitude / longitude of the measurement point Ra, the friction coefficient, the distinction between the upper limit μ and the lower limit μ, and the temperature. The information center stores the road surface information transmitted from the first probe car P1 in the road surface information storage unit.

  Similarly, the second probe car P2 acquires road surface information of the road R and transmits it to the computer C. The road surface information storage unit in the computer C stores road surface information transmitted from many other vehicles, including road surface information transmitted from the first probe car P1 and the second probe car P2. Further, the road surface information storage unit in the computer C also stores a lot of road surface information acquired at points other than the measurement point Ra.

  Here, when the probe cars P1 and P2 can travel in the grip state, the acquired road surface information is recorded as the lower limit μ. When the vehicle is driven in a non-grip state, it is recorded as the upper limit μ. The lower limit μ is a friction coefficient that is not expected to have a frictional resistance lower than the friction coefficient. The upper limit μ is a value close to the actual friction coefficient. However, the upper limit μ cannot be obtained unless the probe cars P1 and P2 are traveling at the grip limit.

  In the computer C, the road surface information transmitted from the probe cars P1, P2 is corrected, and the corrected road surface information is recorded. When correcting the road surface information, the information acquired by the probe car is classified for each temperature, and linear interpolation is performed for the position and the temperature. Furthermore, by determining the topography of mountains and the like based on elevation information published by the navigation system and the Geospatial Information Authority of Japan, by estimating the places where the friction coefficient is low due to freezing etc. due to many shades such as roads on the north side of the mountains, Even when the road surface information by the probe car is insufficient, the estimation accuracy of the friction coefficient on the road can be improved.

  Then, when the host vehicle M travels on the road R, road surface information regarding the road R is transmitted from the computer C to the host vehicle M. In the own vehicle M, the road surface information transmitted from the computer C is received by the transmission / reception device, and the traveling control using the received road surface information is performed. In having road surface information, if there is road surface information having a temperature close to the position where the vehicle M travels, the road surface information can be used.

  Also, if there is no road surface information that is close to the temperature, select candidate points according to the characteristics of the upper and lower limits and temperature, such as “First upper limit μ when the temperature is high, and lower limit μ when the temperature is low”. After obtaining a good friction coefficient, a running pattern including a speed pattern can be generated. By generating the travel pattern in this way, it is possible to generate a travel pattern that is suitable when the host vehicle M travels.

  Furthermore, the friction coefficient can be corrected by estimating a road with a high possibility of freezing, such as a north surface road, from surrounding altitude information. According to these methods, it is possible to deal with roads with a generally uneven μ distribution, and even in time zones and local roads where it is difficult to obtain a fresh thing with a probe car, A traveling pattern suitable for traveling can be generated.

  DESCRIPTION OF SYMBOLS 1 ... Travel control ECU, 2 ... Road surface condition acquisition part, 3 ... Friction coefficient map production | generation part, 4 ... Control amount calculation part, 10 ... Road surface information acquisition ECU, 11 ... Grip state determination part, 12 ... Friction coefficient calculation part, 13 DESCRIPTION OF SYMBOLS ... Traveling position acquisition part, 14 ... Road surface information recording part, 15 ... Road surface information storage part, 21 ... Brake pedal sensor, 22 ... Accel pedal sensor, 23 ... Steering angle sensor, 24 ... G sensor, 25 ... Yaw rate sensor, 26 ... Wheel speed sensor, 27 ... Lane recognition sensor, 28 ... Navigation system, 29A ... VSC ECU, 29B ... ABS ECU, 29C ... TRC ECU, 31 ... Throttle actuator, 32 ... Brake actuator, 33 ... Steering actuator, C ... Computer, M ... Own vehicle , P1 ... first probe car, P2 ... second probe car, R ... road.

Claims (3)

Road surface information acquisition means for acquiring, as road surface information, a friction coefficient of a road surface on which the vehicle travels, based on a vehicle state in the vehicle;
Traveling position acquisition means for acquiring the traveling position of the vehicle;
A road surface information acquisition device comprising: road surface information recording means for recording the road surface information acquired by the road surface information acquisition means in association with the travel position of the vehicle acquired by the travel position acquisition means,
Grip state determination means for determining whether the vehicle is in a grip state or a non-grip state with respect to the road surface;
The road surface information recording means performs discrimination according to the determination result by the grip state determination means, records the road surface information ,
A road surface information acquisition apparatus that records road surface information acquired immediately before the non-grip state is determined as an upper limit friction coefficient .   The road surface information acquisition apparatus according to claim 1, wherein road surface information when the grip state is determined is recorded as a lower limit friction coefficient. On the basis of the road information recorded by the road information recording means, the road information acquisition apparatus according to claim 1 or 2 further comprising a friction coefficient map generating means for generating a friction coefficient map corresponding to the traveling path of the vehicle.

Images