vehicle

Abstract

To properly control driving force of a vehicle.SOLUTION: A vehicle comprises: a first detection unit detecting first road surface information related to a road surface state of a first road surface which is a road surface at a present position contacted by driving wheels of the vehicle; a second detection unit detecting second road surface information related to a road surface state of a second road surface which is a road surface positioned in front of the vehicle; and a control unit controlling driving force of the vehicle by using a road surface friction coefficient estimated from at least one of the first road surface information and the second road surface information. The control unit performs processing including: determining whether or not a road surface state of the first road surface and a road surface state of the second road surface are the same kind of road surface state, on the basis of the first road surface information and the second road surface information; and controlling driving force of the vehicle by applying the first road surface friction coefficient estimated from the first road surface information in place of a second road surface friction coefficient, as a road surface friction coefficient of the second road surface, in the case that a road surface state of the first road surface and a road surface state of the second road surface are the same kind of road surface state.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a vehicle.

Background Art

[0002] [[ID=eleven]] In conventional vehicles, there is a device for controlling the driving force of driving wheels in order to prevent the driving wheels of the vehicle from slipping. For example, in Patent Document 1, based on an image of the road surface in front of the vehicle captured by a camera, the friction coefficient of the road surface in front of the vehicle is estimated, and based on the friction coefficient, the maximum driving force of the driving wheels is calculated, and the driving force of the driving wheels is controlled so as to fall within the range below the maximum driving force.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As in Patent Document 1, by estimating the friction coefficient of the road surface in front of the vehicle using a non-contact sensor such as a camera, it is possible to control the driving force, etc. in advance before the vehicle travels on the road surface in front, and prevent slipping. However, non-contact sensors such as cameras have lower accuracy in estimating the friction coefficient of the road surface than contact sensors installed on driving wheels, etc. Therefore, there was a possibility that an appropriate upper limit of the driving force could not be set and the driving force could not be appropriately controlled with the friction coefficient of the road surface estimated by a non-contact sensor such as a camera.

[0005] Therefore, an object of the present invention is to appropriately control the driving force of a vehicle.

Means for Solving the Problems

[0006] To solve the above problems, a vehicle according to one embodiment of the present invention is provided. A first detection unit detects first road surface information relating to the road surface condition of the first road surface, which is the road surface at the current position where the vehicle's drive wheels are in contact, A second detection unit that detects second road surface information relating to the road surface condition of a second road surface located in front of the vehicle in a non-contact manner, A control unit that controls the driving force of the vehicle using a road surface friction coefficient estimated from at least one of the first road surface information and the second road surface information, Equipped with, The first detection unit detects, as the road surface conditions of the first road surface, left-side first road surface information relating to the road surface condition of the left-side first road surface, which is the road surface to the left of the direction of travel of the vehicle, and right-side first road surface information relating to the road surface condition of the right-side first road surface, which is the road surface to the right of the direction of travel of the vehicle. The second detection unit detects, in a non-contact manner, the road surface conditions of the second road surface, specifically the left-side second road surface, which is the road surface to the left of the vehicle's direction of travel, and the right-side second road surface, which is the road surface to the right of the vehicle's direction of travel. The control unit comprises one or more processors and one or more memories connected to the processors. The aforementioned processor, Based on the first road surface information and the second road surface information, it is determined whether the road surface condition of the first road surface and the road surface condition of the second road surface are of the same type. When the road surface conditions of the first road surface and the road surface conditions of the second road surface are of different types, the driving force of the vehicle is controlled using the second road surface friction coefficient estimated from the second road surface information as the road surface friction coefficient of the second road surface, When the road surface condition of the first road surface and the road surface condition of the second road surface are of the same type, the driving force of the vehicle is controlled by using the first road surface friction coefficient estimated from the first road surface information instead of the second road surface friction coefficient. Using the road surface friction coefficients of the left and right sides, the upper limits of the driving force of the left and right drive wheels are calculated independently to control the driving force of the vehicle. Using the left-side first road surface information and the left-side second road surface information, the left-side upper limit driving force is set as the upper limit driving force of the left-side drive wheel of the vehicle, Using the aforementioned right-side first road surface information and the aforementioned right-side second road surface information, the right-side upper limit driving force is set as the upper limit driving force of the right-side drive wheel of the vehicle, The lower of the left-side upper limit driving force and the right-side upper limit driving force is set as the overall upper limit driving force of the vehicle, thereby setting the overall upper limit driving force. If the requested driving force input by the driver exceeds the overall upper limit driving force, the driving force of the drive wheel on the side set to the upper limit driving force corresponding to the overall upper limit driving force is limited to or less than the overall upper limit driving force, and the difference between the requested driving force and the overall upper limit driving force is added to the driving force of the other drive wheel. Execute the process that includes this. To solve the above problems, a vehicle according to one embodiment of the present invention is provided. A first detection unit detects first road surface information relating to the road surface condition of the first road surface, which is the road surface at the current position where the vehicle's drive wheels are in contact, A second detection unit that detects second road surface information relating to the road surface condition of a second road surface located in front of the vehicle in a non-contact manner, An external information receiving unit receives a third road surface information relating to the road surface condition of the third road surface, which is the road surface located in front of the vehicle and includes the second road surface, from an information distribution device connected to the vehicle via a network. A control unit that controls the driving force of the vehicle using a road surface friction coefficient estimated from at least one of the first road surface information and the second road surface information, Equipped with, The control unit comprises one or more processors and one or more memories connected to the processors. The aforementioned processor, Based on the first road surface information and the second road surface information, it is determined whether the road surface condition of the first road surface and the road surface condition of the second road surface are of the same type. If the second detection unit cannot detect the second road surface information, the system determines, based on the third road surface information, whether the road surface condition of the first road surface and the road surface condition of the second road surface are of the same type, as road surface information relating to the road surface condition of the second road surface. <​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​

[0010] [1. Overall configuration of the vehicle and vehicle control system according to the first embodiment] First, with reference to Figure 1, the overall configuration of the vehicle control system 1 equipped with a vehicle 10 according to the first embodiment of the present invention will be described. Figure 1 is a schematic diagram showing the overall configuration of the vehicle control system 1 equipped with a vehicle 10 according to the first embodiment. As shown in Figure 1, the vehicle control system 1 includes a vehicle 10, an information distribution device 20, and a network 30. The vehicle 10 and the information distribution device 20 are connected via the network 30.

[0011] Vehicle 10 is an automobile capable of traveling on roads. Vehicle 10 is, for example, an engine-powered vehicle equipped with an engine as a power source for driving. Vehicle 10 may also be a hybrid vehicle equipped with both an engine and a motor as power sources for driving, or an electric vehicle equipped with a motor as a power source for driving. Furthermore, vehicle 10 may be an autonomous vehicle equipped with an autonomous driving function.

[0012] As shown in Figure 1, the vehicle 10 comprises a control unit 100, a contact-type detection unit 110, a non-contact-type detection unit 120, an external information detection unit 130, and a vehicle drive unit 140. The vehicle 10 also includes a communication unit capable of transmitting and receiving various types of information wirelessly or via wired connection to external devices such as an information distribution device 20.

[0013] The control unit 100 functions as a vehicle control device that controls the driving force of the vehicle 10. The control unit 100 controls the driving force of the vehicle 10 using, for example, a road surface friction coefficient μ estimated from at least one of the first road surface information and the second road surface information, which will be described later. The road surface friction coefficient μ is, for example, an index that represents the friction state of the road surface. The road surface information is, for example, information that is directly or indirectly related to the road surface condition of the road surface. As shown in Figure 1, the control unit 100 has a processor 102 and a memory 104 connected to the processor 102.

[0014] The processor 102 is an arithmetic processing unit installed in a computer. The processor 102 is composed of, for example, a CPU (Central Processing Unit), but may also be composed of other microprocessors. Furthermore, the processor 102 may be composed of one or more processors. The processor 102 executes programs stored in the memory 104 or other storage medium, thereby executing various processes in the control unit 100.

[0015] Memory 104 is a storage medium for storing programs and various other data. Memory 104 includes, for example, RAM (Random Access Memory) and ROM (Read Only Memory). ROM is a non-volatile memory that stores programs used by the processor 102, and data necessary to run those programs. RAM is a volatile memory that temporarily stores data such as variables, arithmetic parameters, and calculation results used in processes executed by the processor 102. Programs stored in ROM are read into RAM and executed by the processor 102, such as the CPU.

[0016] The contact-type detection unit 110 is an example of the first detection unit. The contact-type detection unit 110 includes a contact-type sensor 112, a first road surface friction coefficient estimation unit 114, and a driving condition determination unit 116. The contact-type sensor 112 may be at least one or more combinations of, for example, a vehicle speed sensor, a two-wheel drive wheel speed sensor or a four-wheel drive wheel speed sensor, a steering angle sensor, a yaw rate sensor, an accelerator opening sensor, a brake pedal switch, a brake fluid pressure sensor, a steering torque sensor, a longitudinal acceleration sensor, and a lateral acceleration sensor. The contact-type sensor 112 may also be, for example, a sensor provided in the engine that detects engine torque, engine speed, or throttle opening, a sensor provided in the transmission that detects turbine speed, transmission gear ratio, or differential limiting clutch engagement torque, or a sensor provided in the electric power steering that detects assist force by electric power steering.

[0017] The contact-type sensor 112 detects, for example, first road surface information relating to the road surface condition of the first road surface by contact. The road surface condition refers to various conditions relating to the road surface, such as conditions that can affect the frictional force between the drive wheels and the road surface. The road surface condition also refers to conditions relating to the slipperiness of the road surface. The road surface condition can be divided into, for example, high-μ roads where the road surface friction coefficient μ is above a predetermined threshold, and low-μ roads where the road surface friction coefficient μ is below the predetermined threshold. The predetermined threshold is, for example, 0.5. However, it is not limited to this, and the road surface condition may be divided into three or more categories by multiple thresholds of the road surface friction coefficient μ. Furthermore, the road surface condition may be classified according to the type of road surface, such as dry road surface (DRY), wet road surface (WET), snow-covered road surface (SNOW), and frozen road surface (ICE). The first road surface is the road surface at the current position where the drive wheels of the vehicle 10 are in contact. The first road surface information is information directly or indirectly related to the road surface condition of the first road surface, and may, for example, be information relating to the operation of the vehicle 10 that reflects the road surface condition of the first road surface. For example, the first road surface information may be at least one or more combinations of the following: vehicle speed, wheel speed, steering angle, yaw rate, accelerator opening, brake operation signal, brake operation amount, brake fluid pressure, longitudinal acceleration, lateral acceleration, engine speed, throttle opening, engine torque, turbine speed, transmission gear ratio, differential limiting clutch engagement torque, driver steering force, and electric power steering assist force.

[0018] The first road surface friction coefficient estimation unit 114 estimates the first road surface friction coefficient μ1, which is the road surface friction coefficient μ of the first road surface, from the first road surface information detected by the contact-type sensor 112. The first road surface friction coefficient estimation unit 114 can estimate the first road surface friction coefficient μ1 using multiple estimation methods. The driving conditions determined by the driving condition determination unit 116, which will be described later, are mainly of three types: acceleration, deceleration, and turning. The estimation methods corresponding to these three types of driving conditions will be described below.

[0019] First, the method for estimating the first road surface friction coefficient μ1 when the driving state is in an acceleration state will be explained. The first road surface friction coefficient estimation unit 114 calculates the generated braking force based on the requested driving force input by the driver. Then, the first road surface friction coefficient estimation unit 114 calculates the generated braking force difference value, which is the difference between the current value of the generated braking force and the past value of the generated braking force. The first road surface friction coefficient estimation unit 114 also calculates the estimated braking force based on the engine speed, throttle opening, turbine speed, transmission gear ratio, and brake fluid pressure detected by the contact sensor 112. Then, the first road surface friction coefficient estimation unit 114 calculates the estimated braking force difference value, which is the difference between the current value of the estimated braking force and the past value of the estimated braking force. Finally, the first road surface friction coefficient estimation unit 114 calculates the driving stiffness coefficient using the generated braking force difference value and the estimated braking force difference value. The first road surface friction coefficient estimation unit 114 applies the driving stiffness coefficient and the vehicle speed detected by the contact sensor 112 to a characteristic map to estimate the first road surface friction coefficient μ1. The characteristic map is a map that shows the relationship between the pre-stored driving stiffness coefficient, vehicle speed, and road surface friction coefficient μ.

[0020] Next, the method for estimating the first road surface friction coefficient μ1 when the driving state is decelerating will be explained. The first road surface friction coefficient estimation unit 114 calculates the front wheel speed and the rear wheel speed based on the wheel speed detected by the contact-type sensor 112, and sets the rear wheel speed as the vehicle speed. Then, the first road surface friction coefficient estimation unit 114 performs differential processing on the vehicle speed to calculate the vehicle deceleration. Subsequently, if certain conditions are met, the first road surface friction coefficient estimation unit 114 calculates the difference in front and rear wheel slip rates based on the vehicle speed, the front wheel speed, and the rear wheel speed, and applies this difference in front and rear wheel slip rates and the vehicle deceleration to a judgment map to estimate the instantaneous value of the road surface friction coefficient μM. The judgment map is a map that shows the relationship between the front and rear wheel slip rate difference, the vehicle deceleration, and the road surface friction coefficient μ, which are stored in advance. Subsequently, the first road surface friction coefficient estimation unit 114 determines that the brake operation signal detected by the contact sensor 112 is ON, and the vehicle deceleration is at a first threshold (for example, 0.5 m / s) 2The system determines whether the condition described above has continued for a certain period of time. If the condition has continued for a certain period of time, the first road surface friction coefficient estimation unit 114 determines that the instantaneous value of the road surface friction coefficient μM is μMH (for example, 1.0) or higher, and the vehicle deceleration is above the second threshold (for example, 2.0 m / s) 2 ) or if the instantaneous road surface friction coefficient μM is μMM (e.g., 0.75) or higher, and the vehicle deceleration is above the third threshold (e.g., 1.3 m / s) 2 ) or if the instantaneous road surface friction coefficient μM is μML (e.g., 0.3) or higher, and the vehicle deceleration is above the fourth threshold (e.g., 0.5 m / s 2 If the value is greater than or equal to ), the first road surface friction coefficient μ1 is updated with the instantaneous road surface friction coefficient μM.

[0021] Finally, the method for estimating the first road surface friction coefficient μ1 when the vehicle is in a turning state will be explained. First, the first road surface friction coefficient estimation unit 114 calculates the front wheel friction circle utilization rate based on engine torque, engine speed, main transmission gear ratio, turbine speed, differential limiting clutch engagement torque, yaw rate, and lateral acceleration. Next, the first road surface friction coefficient estimation unit 114 calculates the estimated rack thrust based on the steering angle, driver steering force, and assist force from the electric power steering. The first road surface friction coefficient estimation unit 114 also calculates the reference rack thrust based on the front wheel slip angle. The front wheel slip angle is calculated from the steering angle, yaw rate, and vehicle speed. Then, the first road surface friction coefficient estimation unit 114 calculates the rack thrust deviation based on the estimated rack thrust and the reference rack thrust. Subsequently, the first road surface friction coefficient estimation unit 114 compares the rack thrust deviation with the maximum value determination threshold. If the rack thrust deviation is greater than or equal to the maximum value determination threshold, it sets the front wheel friction circle utilization rate as the first road surface friction coefficient μ1. If the rack thrust deviation is less than the maximum value determination threshold, the first road surface friction coefficient estimation unit 114 uses the vehicle speed and the front wheel slip angle to refer to the recovery speed map and calculates the first road surface friction coefficient μ1 while restoring the road surface friction coefficient at the recovery speed. The recovery speed map is a map in which the recovery speed that restores the road surface friction coefficient μ to a predetermined set value based on the vehicle speed and the front wheel slip angle is pre-set.

[0022] As explained above, the first road surface friction coefficient estimation unit 114 estimates the first road surface friction coefficient μ1 using an estimation method corresponding to the acceleration state, for example, when the driving condition determination unit 116, which will be described later, determines that the vehicle 10 is in an acceleration state. The same applies when the vehicle 10 is in a deceleration state or a turning state.

[0023] The driving status determination unit 116 determines the driving state of the vehicle 10 from the first road surface information detected by the contact sensor 112. For example, the driving status determination unit 116 determines that the vehicle 10 is accelerating if the acceleration of the vehicle 10 detected by the contact sensor 112 is greater than or equal to a predetermined value. However, it is not limited to this, for example, the driving status determination unit 116 may determine that the vehicle 10 is accelerating when the contact sensor 112 detects the acceleration of the vehicle 10. Also, the driving status determination unit 116 determines that the vehicle 10 is decelerating if the amount of brake operation detected by the contact sensor 112 is greater than or equal to a predetermined value. However, it is not limited to this, for example, the driving status determination unit 116 may determine that the vehicle 10 is decelerating when the contact sensor 112 detects the amount of brake operation. Also, the driving status determination unit 116 determines that the vehicle 10 is turning if the steering angle detected by the contact sensor 112 is greater than or equal to a predetermined value. However, this is not limited to the above. For example, when the contact sensor 112 detects the steering wheel angle, the driving condition determination unit 116 may determine that the vehicle 10 is in a turning state.

[0024] As described above, the contact-type detection unit 110 detects the first road surface information by contact and estimates the first road surface friction coefficient μ1 using the detected first road surface information.

[0025] The non-contact detection unit 120 is an example of a second detection unit. The non-contact detection unit 120 includes a non-contact sensor 122 and a second road surface friction coefficient estimation unit 124. The non-contact sensor 122 may be at least one or more combinations of, for example, a camera that images the area in front of the vehicle 10, an outside temperature sensor, a road surface temperature sensor, a near-infrared sensor, and a laser light sensor. The non-contact sensor 122 detects, for example, second road surface information relating to the road surface condition of the second road surface in a non-contact manner. The second road surface is a road surface located a predetermined distance ahead from the current position of the vehicle 10, for example, a road surface about 100m ahead. The second road surface information is information directly or indirectly related to the road surface condition of the second road surface, and may be, for example, information relating to the condition of the second road surface that reflects the road surface condition of the second road surface. For example, the second road surface information may be at least one or more combinations of the following: an image of the area in front of the vehicle 10, ambient temperature, road surface temperature, road surface unevenness, road surface moisture content, and the roughness of the road surface in front of the vehicle 10.

[0026] The second road surface friction coefficient estimation unit 124 estimates the second road surface friction coefficient μ2, which is the road surface friction coefficient μ of the second road surface, from the second road surface information detected by the non-contact sensor 122. Specifically, the second road surface friction coefficient estimation unit 124 applies, for example, the road surface temperature, road surface irregularities, and road surface moisture content detected by the non-contact sensor 122 to a road surface condition map and determines whether the road surface condition of the second road surface is "DRY," "WET," "SNOW," or "ICE." However, it is not limited to this, and the second road surface friction coefficient estimation unit 124 may also determine, for example, whether the road surface condition of the second road surface is a high-μ road, a low-μ road, a paved road, an unpaved road, asphalt, or concrete. The road surface condition map is a map that associates the road surface conditions "DRY," "WET," "SNOW," and "ICE" with the road surface temperature, road surface irregularities, and road surface moisture content, which are stored in advance. The second road surface friction coefficient estimation unit 124 then estimates the second road surface friction coefficient μ2 to a value within the range of 0.65 to 1.0 when the road surface condition is "DRY", and when the road surface condition is "WET", it estimates the second road surface friction coefficient μ2 to a value within the range of 0.45 to 0.7. Furthermore, the second road surface friction coefficient estimation unit 124 estimates the second road surface friction coefficient μ2 to a value within the range of 0.25 to 0.6 when the road surface condition is "SNOW", and when the road surface condition is "ICE", it estimates the second road surface friction coefficient μ2 to a value within the range of 0.05 to 0.3. The second road surface friction coefficient estimation unit 124 then sets the median value of the range of road surface friction coefficient μ defined for each of the above road surface conditions as the second road surface friction coefficient μ2. However, it is not limited to this, and the second road surface friction coefficient estimation unit 124 may, for example, set the upper or lower limit of the range of the road surface friction coefficient μ as the second road surface friction coefficient μ2. Also, the second road surface friction coefficient estimation unit 124 may estimate it to any value within the range for each road surface condition, depending on parameters caused by the road surface condition (road surface unevenness, water film thickness, snow density, snow moisture content, road surface temperature, etc.).

[0027] As described above, the non-contact detection unit 120 detects the second road surface information in a non-contact manner and estimates the second road surface friction coefficient μ2 using the detected second road surface information.

[0028] The external information detection unit 130 includes an external information receiving unit 132 and a third road surface friction coefficient estimation unit 134. The external information receiving unit 132 is an example of the communication unit described above and is connected to the information distribution device 20 via the network 30. The external information receiving unit 132 receives, for example, external information regarding the road surface condition of the third road surface from the information distribution device 20. The third road surface is a road surface located a predetermined distance ahead from the current position of the vehicle 10, for example, a road surface approximately 100m to several kilometers away from the current location of the vehicle 10. The third road surface may include the second road surface. In this case, the external information regarding the road surface condition of the third road surface may include external information regarding the road surface condition of the second road surface. The external information is information directly or indirectly related to the road surface condition of the third road surface, and may, for example, be information regarding the condition of the third road surface that reflects the road surface condition of the third road surface. For example, the external information may be at least one or more combinations of road images, ambient temperature, road surface temperature, road surface unevenness, road surface moisture content, road surface roughness, etc. Alternatively, the external information may be, for example, road traffic information, road freezing information, weather information, or slip information from other vehicles. The various types of external information received by the external information receiving unit 132 described above may be associated with the detection location and detection time by, for example, the information distribution device 20 and transmitted back to the external information receiving unit 132.

[0029] The third road surface friction coefficient estimation unit 134 estimates the third road surface friction coefficient μ3, which is the road surface friction coefficient μ of the third road surface, from the third road surface information received by the external information receiving unit 132. Specifically, the third road surface friction coefficient estimation unit 134 estimates the third road surface friction coefficient μ3 using the same estimation method as the second road surface friction coefficient estimation unit 124. However, it is not limited to this, and the third road surface friction coefficient estimation unit 134 may also directly detect the road surface condition using, for example, at least one or more combinations of road traffic information, road freezing information, weather information, and slip information of other vehicles received by the external information receiving unit 132.

[0030] As described above, the external information detection unit 130 receives external information from the information distribution device 20 and uses the received external information to estimate the third road surface friction coefficient μ3.

[0031] The vehicle drive unit 140 is a motor or engine, etc., that drives the drive wheels of the vehicle 10. The vehicle drive unit 140 is connected to the control unit 100. The vehicle drive unit 140 drives the drive wheels, for example, in response to a signal from the control unit 100.

[0032] The information distribution device 20 is connected to the vehicle 10 via the network 30 and transmits external information to the vehicle 10. The information distribution device 20 transmits external information acquired by an information collection terminal to the vehicle 10, for example. The information distribution device 20 is, for example, a road information provision system, a weather information distribution system, etc. However, it is not limited to this, and the information distribution device 20 may be, for example, a device that is placed in various locations on the road surface and distributes external information to vehicles traveling on a certain section of the road surface. The information collection terminal is, for example, a camera or weather observation device placed in various locations on the road surface, for example. However, it is not limited to this, and the information collection terminal may be, for example, a road surface condition measurement vehicle, a snowplow, or another general vehicle. The information collection terminal is also a detection device that is placed in various locations on the road surface and detects the road surface condition, and may be, for example, a road surface temperature sensor, a near-infrared sensor, or a laser light sensor, etc. The information distribution device 20 distributes at least one or more combinations of, for example, road traffic information, road freezing information, and weather information, etc., to the vehicle 10. Furthermore, the information distribution device 20 may, for example, distribute to the vehicle 10 information regarding the road surface condition detected by a road surface condition measuring vehicle, a snowplow, or other general vehicle, or it may distribute to the vehicle 10 information detected by various sensors placed at various locations on the road surface.

[0033] [2. Functional configuration of the control unit of the vehicle according to the first embodiment] Next, with reference to Figure 2, the functional configuration of the control unit 100 of the vehicle 10 according to the first embodiment will be described. Figure 2 is a block diagram showing an example of the functional configuration of the control unit 100 of the vehicle 10 according to the first embodiment. In addition, when explaining the functional configuration of the control unit 100 of the vehicle 10 according to the first embodiment, Figure 3 will be used as necessary. Figure 3 is a diagram illustrating the control of the vehicle 10 according to the first embodiment. Figure 3 shows four patterns of combinations of the road surface conditions of the first road surface and the road surface conditions of the second road surface, and the control processing of the control unit 100 in each pattern will be explained. The four patterns are: (A) same type of road surface condition (high μ road - high μ road), (B) same type of road surface condition (low μ road - low μ road), (C) different types of road surface conditions (high μ road - low μ road), and (D) different types of road surface conditions (low μ road - high μ road). In the four patterns, the part before "-" indicates the road surface condition of the first road surface, and the part after "-" indicates the road surface condition of the second road surface.

[0034] First, as shown in Figure 2, the control unit 100 includes an information acquisition unit 300, a road surface condition determination unit 302, a road surface friction coefficient setting unit 304, an upper limit driving force setting unit 306, and a driving force control unit 308.

[0035] The information acquisition unit 300 acquires road surface information. For example, the information acquisition unit 300 acquires first road surface information and a first road surface friction coefficient μ1 detected by the contact-type detection unit 110. The information acquisition unit 300 also acquires second road surface information detected by the non-contact-type detection unit 120, information representing the road surface condition of the second road surface, and a second road surface friction coefficient μ2. Furthermore, if the non-contact-type detection unit 120 cannot detect the second road surface information, the information acquisition unit 300 acquires external information received by the external information detection unit 130, information representing the road surface condition of the third road surface, and a third road surface friction coefficient μ3.

[0036] For example, if the road in front of vehicle 10 has a sharp curve, if the road in front of vehicle 10 has a gentle curve and there is an obstacle on the inside of the curved road, or if vehicle 10 is turning at an intersection, it is not possible to see what is in front of vehicle 10. For example, a non-contact sensor 122 such as a camera or laser can image or measure a straight road ahead, but it cannot image or measure what is beyond a curved road ahead. In this case, the non-contact detection unit 120 will not be able to detect the second road surface information of the road ahead.

[0037] Furthermore, for example, when vehicle 10 is traveling at high speed, there is a risk that vehicle 10 may reach the second road surface before the control unit 100 can estimate the second road surface friction coefficient μ2 from the second road surface information and control the driving force of vehicle 10. For this reason, vehicle 10 needs to acquire road surface information about the road surface located approximately 100m or more ahead of vehicle 10. However, non-contact sensors 122, such as cameras or lasers, cannot detect road surface information about the road surface located approximately 100m or more ahead of vehicle 10.

[0038] Thus, if the non-contact detection unit 120 cannot detect the second road surface information, the information acquisition unit 300 acquires and uses external information as road surface information relating to the road surface condition of the second road surface, instead of the second road surface information.

[0039] The road surface condition determination unit 302 determines whether the road surface condition of the first road surface and the road surface condition of the second road surface (hereinafter sometimes referred to as "the two road surface conditions") are of the same type. The road surface condition determination unit 302 determines that the two road surface conditions are of the same type if, for example, both road surface conditions are high-μ roads, or both road surface conditions are low-μ roads. However, it is not limited to this, and for example, the road surface condition determination unit 302 determines that the two road surface conditions are of the same type if both road surface conditions are one of the following: "DRY", "WET", "SNOW", or "ICE". Alternatively, for example, the road surface conditions may be classified as high-μ roads if they are "DRY" or "WET", and as low-μ roads if they are "SNOW" or "ICE". In this case, the road surface condition determination unit 302 may also determine that the two road surface conditions are of the same type if both are "DRY" or "WET". Furthermore, if both road surface conditions are "SNOW" or "ICE," they may similarly be determined to be the same type of road surface condition. Also, the road surface condition determination unit 302 may determine that two road surface conditions are the same type if, for example, one of the two road surface conditions is a high-μ road and the other is "DRY." Furthermore, if the combination of one road surface condition and the other is a high-μ road and "WET," or a low-μ road and "SNOW," or a low-μ road and "ICE," both road surface conditions may similarly be determined to be the same type of road surface condition.

[0040] The road surface condition determination unit 302 determines, for example, whether the road surface condition of the first road surface and the road surface condition of the second road surface are of the same type, based on the first road surface friction coefficient μ1 and the second road surface friction coefficient μ2.

[0041] For example, the road surface condition determination unit 302 determines whether the first road surface friction coefficient μ1 detected by the contact-type detection unit 110 is above a predetermined threshold, and determines whether the road surface condition of the first road surface is high μ or low μ. Similarly, the road surface condition of the second road surface is determined by the second road surface friction coefficient μ2. Subsequently, as shown in Figure 3(A), if both the road surface condition of the first road surface and the road surface condition of the second road surface are high μ, or as shown in Figure 3(B), if both are low μ, the road surface condition determination unit 302 determines that the road surface condition of the first road surface and the road surface condition of the second road surface are of the same type. On the other hand, as shown in Figure 3(C), there are cases where the road surface condition of the first road surface is high μ and the road surface condition of the second road surface is low μ, or as shown in Figure 3(D), there are cases where the road surface condition of the first road surface is low μ and the road surface condition of the second road surface is high μ. In these cases, the road surface condition determination unit 302 determines that the road surface condition of the first road surface and the road surface condition of the second road surface are of different types.

[0042] Furthermore, the road surface condition determination unit 302 may determine, for example, whether the road surface condition of the first road surface and the road surface condition of the second road surface are of the same type, based on the first road surface friction coefficient μ1 and the road surface condition of the second road surface determined by the non-contact detection unit 120. Specifically, as described above, the road surface condition determination unit 302 determines the road surface condition of the first road surface based on the first road surface friction coefficient μ1. Then, the road surface condition determination unit 302 determines whether the road surface condition of the first road surface and the road surface condition of the second road surface determined by the non-contact detection unit 120, for example, one of the states "DRY", "WET", "SNOW", or "ICE", are of the same type. For example, the road surface condition determination unit 302 determines that the road surface conditions are of the same type if the road surface condition of the first road surface is a high μ road and the road surface condition of the second road surface is "DRY".

[0043] As described above, the road surface condition determination unit 302 determines whether the road surface condition of the first road surface and the road surface condition of the second road surface are of the same type, based on the first road surface information and the second road surface information. If the second road surface information cannot be detected by the non-contact detection unit 120, the road surface condition determination unit 302 determines whether the road surface condition of the first road surface and the road surface condition of the second road surface are of the same type, based on the first road surface information and external information. The specific determination method in this case is the same as in the case based on the first road surface friction coefficient μ1 and the second road surface friction coefficient μ2 described above, and in the case based on the first road surface friction coefficient μ1 and the road surface condition of the second road surface determined by the non-contact detection unit 120.

[0044] Furthermore, the road surface condition determination unit 302 determines, for example, whether the road surface condition of the first road surface is better than that of the second road surface, based on the first road surface information and the second road surface information. A good road surface condition is, for example, a condition in which the road surface friction coefficient μ is high. For example, as shown in Figure 3(C), if the road surface condition of the first road surface is a high μ road and the road surface condition of the second road surface is a low μ road, the road surface condition of the first road surface is better than that of the second road surface. Also, as shown in Figure 3(D), if the road surface condition of the first road surface is a low μ road and the road surface condition of the second road surface is a high μ road, the road surface condition of the first road surface is worse than that of the second road surface.

[0045] Returning to Figure 2, the road surface friction coefficient setting unit 304 sets the road surface friction coefficient μ corresponding to the road surface. For example, the road surface friction coefficient setting unit 304 sets a first road surface friction coefficient μ1 for the first road surface. Also, for example, the road surface friction coefficient setting unit 304 sets a second road surface friction coefficient μ2 for the second road surface. Furthermore, if the non-contact detection unit 120 cannot detect the second road surface information, the road surface friction coefficient setting unit 304 sets a third road surface friction coefficient μ3 for the second road surface.

[0046] Furthermore, the road surface friction coefficient setting unit 304 sets the road surface friction coefficient μ corresponding to each road surface, for example, based on the determination result by the road surface condition determination unit 302.

[0047] For example, as shown in Figures 3(A) and 3(B), if it is determined that the road surface condition of the first road surface and the road surface condition of the second road surface are of the same type, the road surface friction coefficient setting unit 304 sets the road surface friction coefficient μ of the first road surface to the first road surface friction coefficient μ1 estimated from the first road surface information, and also sets the road surface friction coefficient μ of the second road surface to the same first road surface friction coefficient μ1. In this way, the road surface friction coefficient setting unit 304 sets the road surface friction coefficient μ for the second road surface to the first road surface friction coefficient μ1 instead of the second road surface friction coefficient μ2. The same applies when a third road surface friction coefficient μ3 is set for the second road surface.

[0048] On the other hand, for example, as shown in Figures 3(C) and 3(D), if it is determined that the road surface conditions of the first road surface and the second road surface are of different types, the road surface friction coefficient setting unit 304 sets the road surface friction coefficient μ of the first road surface to the first road surface friction coefficient μ1 estimated from the first road surface information, and sets the road surface friction coefficient μ of the second road surface to the second road surface friction coefficient μ2 estimated from the second road surface information. In this way, in the cases of Figures 3(C) and 3(D), the road surface friction coefficient μ for the second road surface is not changed from the second road surface friction coefficient μ2 to the first road surface friction coefficient μ1, but the second road surface friction coefficient μ2 is used as is.

[0049] Returning to Figure 2, the upper limit driving force setting unit 306 calculates the upper limit of the driving force of the vehicle 10 (hereinafter referred to as "upper limit driving force") using the road surface friction coefficient μ, and sets the upper limit driving force used to control the driving force of the vehicle 10 to the calculated upper limit driving force. The upper limit driving force setting unit 306 calculates the upper limit driving force, for example, using the road surface friction coefficient μ set for the second road surface.

[0050] For example, when the road surface conditions of the first road surface and the second road surface are of the same type, the upper limit driving force setting unit 306 calculates the upper limit driving force of the vehicle 10 by using the first road surface friction coefficient μ1 instead of the second road surface friction coefficient μ2 as the road surface friction coefficient μ of the second road surface. For example, as shown in Figures 3(A) and 3(B), when it is determined that the road surface conditions of the first road surface and the second road surface are of the same type, the road surface friction coefficient μ for the second road surface is set to the first road surface friction coefficient μ1. Therefore, in the cases of Figures 3(A) and 3(B), the upper limit driving force setting unit 306 calculates the upper limit driving force of the vehicle 10 based on the first road surface friction coefficient μ1 set for the second road surface.

[0051] On the other hand, for example, when the road surface conditions of the first road surface and the second road surface are of different types, the upper limit driving force setting unit 306 calculates the upper limit driving force of the vehicle 10 using the second road surface friction coefficient μ2 as the road surface friction coefficient μ of the second road surface. For example, as shown in Figures 3(C) and 3(D), when it is determined that the road surface conditions of the first road surface and the second road surface are of different types, the road surface friction coefficient μ for the second road surface is set to the second road surface friction coefficient μ2. In the case of Figure 3(C), the upper limit driving force setting unit 306 calculates the upper limit driving force of the vehicle 10 based on the second road surface friction coefficient μ2 set for the second road surface, which is a low-μ road. As will be explained in more detail later, in the case of Figure 3(D), the upper limit driving force setting unit 306 calculates the upper limit driving force of the vehicle 10 based on the first road surface friction coefficient μ1 set for the first road surface, which is a low-μ road.

[0052] Furthermore, the upper limit driving force setting unit 306 may, for example, calculate the upper limit of the driving force of the vehicle 10 using the road surface friction coefficient μ set for the first road surface, according to the determination result by the road surface condition determination unit 302.

[0053] For example, if the road surface conditions of the first road surface and the second road surface are of different types, and the road surface condition of the first road surface is worse than that of the second road surface, the upper limit driving force setting unit 306 calculates the upper limit driving force of the vehicle 10 using the first road surface friction coefficient μ1 as the road surface friction coefficient μ of the first road surface. For example, as shown in Figures 3(C) and 3(D), if the road surface conditions of the first road surface and the second road surface are of different types, the road surface friction coefficient setting unit 304 sets the first road surface friction coefficient μ1 for the first road surface. Similarly, in the same case, the road surface friction coefficient setting unit 304 sets the second road surface friction coefficient μ2 for the second road surface. In this situation, as shown in Figure 3(D), if the road surface condition of the first road surface is worse than that of the second road surface, the upper limit driving force setting unit 306 calculates the upper limit driving force using the first road surface friction coefficient μ1 set for the first road surface with the worse road surface condition.

[0054] On the other hand, for example, if the road surface conditions of the first road surface and the second road surface are of different types, and the road surface condition of the first road surface is better than that of the second road surface, the upper limit driving force setting unit 306 calculates the upper limit driving force of the vehicle 10 using the second road surface friction coefficient μ2 as the road surface friction coefficient μ of the second road surface. For example, as shown in Figure 3(C), if the road surface condition of the first road surface is better than that of the second road surface, the upper limit driving force setting unit 306 calculates the upper limit driving force using the second road surface friction coefficient μ2 that is set for the second road surface which has a worse road surface condition.

[0055] Returning to Figure 2, the drive force control unit 308 controls the drive force of the vehicle 10. The drive force control unit 308 controls the drive force of the vehicle 10 based on, for example, the upper limit drive force set by the upper limit drive force setting unit 306. For example, if the drive force input by the driver's accelerator operation exceeds the upper limit drive force, the drive force control unit 308 controls the actual drive force to be less than or equal to the upper limit drive force and transmits it to the vehicle drive unit 140.

[0056] Furthermore, the drive force control unit 308 controls the driving force of the vehicle 10 according to the determination result of the road surface condition determination unit 302, for example. For example, as shown in Figure 3(C), if the road surface condition of the first road surface and the road surface condition of the second road surface are of different types, and the road surface condition of the first road surface is worse than that of the second road surface, the drive force control unit 308 reduces the speed of the vehicle 10. Specifically, if the first road surface is a high-μ road and the second road surface is a low-μ road, the road surface friction coefficient μ of the road surface in front of the vehicle 10 (second road surface) will be lower than the road surface the vehicle 10 is currently traveling on (first road surface). Therefore, the drive force control unit 308 reduces the speed of the vehicle 10 in advance to a speed corresponding to the road surface friction coefficient μ of the second road surface before entering the road surface in front. In this way, when the road surface conditions ahead of vehicle 10 deteriorate, reducing the speed of vehicle 10 in advance prevents slipping when vehicle 10 enters the road surface ahead, allowing vehicle 10 to travel more safely.

[0057] [3. Processing flow of the vehicle control unit according to the first embodiment] Next, with reference to Figure 4, the processing flow by the control unit 100 of the vehicle 10 according to the first embodiment will be described. Figure 4 is a flowchart showing the vehicle control processing by the control unit 100 according to the first embodiment.

[0058] As shown in Figure 4, first, the information acquisition unit 300 acquires various information from the contact-type detection unit 110 (step S100). Specifically, the information acquisition unit 300 acquires first road surface information and first road surface friction coefficient μ1 from the contact-type detection unit 110. Next, the road surface friction coefficient setting unit 304 sets the road surface friction coefficient μ of the first road surface to the first road surface friction coefficient μ1.

[0059] Subsequently, the information acquisition unit 300 determines whether or not the second road surface information can be detected by the non-contact detection unit 120 (step S102).

[0060] As a result, if the non-contact detection unit 120 determines that it can detect the second road surface information (YES in step S102), the information acquisition unit 300 acquires various information from the non-contact detection unit 120 (step S104). Specifically, the information acquisition unit 300 acquires the second road surface information, information representing the road surface condition of the second road surface, and the second road surface friction coefficient μ2 from the non-contact detection unit 120. Next, the road surface friction coefficient setting unit 304 sets the road surface friction coefficient μ of the second road surface to the second road surface friction coefficient μ2.

[0061] On the other hand, if the non-contact detection unit 120 determines that it is not possible to detect the second road surface information (NO in step S102), the information acquisition unit 300 acquires various information from the external information detection unit 130 (step S106). Specifically, the information acquisition unit 300 acquires external information, information representing the road surface condition of the third road surface, and the third road surface friction coefficient μ3 from the external information detection unit 130. Next, the road surface friction coefficient setting unit 304 sets the road surface friction coefficient μ of the second road surface to the third road surface friction coefficient μ3.

[0062] In step S104, after acquiring various information from the non-contact detection unit 120, or in step S106, after acquiring various information from the external information detection unit 130, the road surface condition determination unit 302 determines whether the road surface condition of the first road surface and the road surface condition of the second road surface are of the same type (step S108).

[0063] As a result, if it is determined that the road surface conditions of the first road surface and the second road surface are of the same type (YES in step S108), the road surface friction coefficient setting unit 304 sets the road surface friction coefficient μ of the second road surface to the first road surface friction coefficient μ1 instead of the second road surface friction coefficient μ2 (step S110).

[0064] Subsequently, the upper limit driving force setting unit 306 calculates the upper limit driving force of the vehicle 10 based on the road surface friction coefficient μ of the second road surface, and sets the upper limit driving force used to control the driving force of the vehicle 10 to the calculated upper limit driving force (step S112).

[0065] On the other hand, if it is determined in step S108 that the road surface conditions are not of the same type (NO in step S108), the road surface condition determination unit 302 determines whether the road surface condition of the first road surface is worse than that of the second road surface (step S114).

[0066] As a result, if it is determined that the road surface condition of the first road surface is better than that of the second road surface (NO in step S114), the drive force control unit 308 reduces the travel speed of the vehicle 10 by an amount corresponding to the reduction in the second road surface friction coefficient μ2 (step S116), and then proceeds to step S112.

[0067] On the other hand, in step S114, if it is determined that the first road surface is in a worse condition than the second road surface (YES in step S114), the upper limit driving force setting unit 306 calculates the upper limit driving force based on the road surface friction coefficient μ of the first road surface. Next, the upper limit driving force setting unit 306 sets the upper limit driving force used to control the driving force of the vehicle 10 to the calculated upper limit driving force (step S118).

[0068] After the upper limit of the driving force is set in step S112, or after the upper limit of the driving force is set in step S118, the driving force control unit 308 controls the driving force of the vehicle 10 based on the set upper limit of the driving force (step S120), and then terminates the vehicle control process.

[0069] As described above, according to the first embodiment, when the road surface condition of the first road surface and the road surface condition of the second road surface are of the same type, the driving force of the vehicle 10 is controlled using the first road surface friction coefficient μ1 obtained by the contact-type detection unit 110 as the road surface friction coefficient μ of both the first and second road surfaces. In this way, when the road surface conditions of the first and second road surfaces are of the same type, the first road surface friction coefficient μ1, which has high estimation accuracy, is used instead of the second road surface friction coefficient μ2, which has poor estimation accuracy. This makes it possible to set a more appropriate upper limit driving force and appropriately control the driving force of the vehicle 10, thereby suppressing driving problems such as slipping.

[0070] Furthermore, according to the first embodiment, when the road surface condition of the first road surface and the road surface condition of the second road surface are of different types, the second road surface friction coefficient μ2 obtained by the non-contact detection unit 120 is used as the road surface friction coefficient μ of the second road surface to control the driving force of the vehicle 10. This prevents the driving force of the vehicle 10 from being controlled using the road surface friction coefficient μ of different types of road surfaces, thereby suppressing driving problems such as slipping.

[0071] Furthermore, according to the first embodiment, if the road surface conditions of the first and second road surfaces are of different types, and the road surface condition of the first road surface is worse than that of the second road surface, the driving force of the vehicle 10 is controlled using the first road surface friction coefficient μ1, which represents the road surface condition of the first road surface. This prevents the driving force from being controlled using a high value for the second road surface friction coefficient μ2, even though the road surface friction coefficient μ of the first road surface currently being driven on is low. Therefore, an appropriate upper limit driving force can be set, and the driving force of the vehicle 10 can be appropriately controlled, preventing slippage on the road surface currently being driven on.

[0072] Furthermore, according to the first embodiment, if the non-contact detection unit 120 cannot detect the second road surface information of the second road surface, the external information detection unit 130 receives external information from the information distribution device 20. Then, using this external information, the road surface condition of the third road surface in front of the vehicle 10 is estimated. As a result, even if the non-contact detection unit 120 cannot detect the second road surface information of the second road surface, the vehicle 10 can be suitably controlled according to the road surface condition in front of the vehicle 10, and the driving force of the vehicle 10 can be controlled stably and appropriately.

[0073] [4. Functional configuration of the control unit of the vehicle according to the second embodiment] Next, a vehicle control system 1 equipped with a vehicle 10 according to a second embodiment of the present invention will be described in detail. Note that the second embodiment is a modified version of the first embodiment, and the differences from the first embodiment will be described below, while detailed descriptions of configurations and functions similar to those of the second embodiment will be omitted.

[0074] In the vehicle 10 according to the first embodiment, it is determined whether the road surface conditions of the first road surface and the second road surface are of the same type, and the driving force of the vehicle 10 is controlled accordingly. In the vehicle 10 according to the second embodiment, if the first road surface and the second road surface are split road surfaces, it is further determined whether the road surface conditions of the first road surface and the second road surface on the left and right sides are of the same type, and the driving force of the vehicle 10 is controlled accordingly. A split road surface is a type of road surface in which the road surface conditions of the left and right sides are different with respect to the direction of travel of the vehicle 10.

[0075] First, the vehicle 10 according to the second embodiment includes a control unit 100, a contact-type detection unit 110, a non-contact-type detection unit 120, an external information detection unit 130, and a vehicle drive unit 140, similar to the components of the vehicle 10 according to the first embodiment.

[0076] The control unit 100 controls the driving force of the vehicle 10 by independently calculating the upper limit driving force of the left drive wheel and the right drive wheel, respectively, using the road surface friction coefficient μ of the left road surface and the right road surface. The road surface friction coefficient μ of the left road surface is, for example, the road surface friction coefficient μ estimated from at least one of the left first road surface information and the left second road surface information, which will be described later. The road surface friction coefficient μ of the right road surface is, for example, the road surface friction coefficient μ estimated from at least one of the right first road surface information and the right first road surface information, which will be described later.

[0077] The control unit 100 calculates the upper limit driving force of the left drive wheel using, for example, the left first road surface friction coefficient μ1L or the left second road surface friction coefficient μ2L, which will be described later, and sets the upper limit driving force used to control the driving force of the left drive wheel to the calculated upper limit driving force. The control unit 100 also calculates the upper limit driving force of the right drive wheel using, for example, the right first road surface friction coefficient μ1R or the right second road surface friction coefficient μ2R, which will be described later, and sets the upper limit driving force used to control the driving force of the right drive wheel to the calculated upper limit driving force. Then, the control unit 100 controls the driving force of the vehicle 10 based on the set upper limit driving forces of the left and right drive wheels.

[0078] The contact-type detection unit 110 detects the left-side first road surface information and the right-side first road surface information of the first road surface as road surface conditions of the first road surface by contact. The left-side first road surface information is information that is directly or indirectly related to the road surface condition of the left-side first road surface, which is the road surface to the left of the direction of travel of the vehicle 10. For example, the left-side first road surface information may be information relating to the operation of the vehicle 10 that reflects the road surface condition of the left-side first road surface. The right-side first road surface information is information that is directly or indirectly related to the road surface condition of the right-side first road surface, which is the road surface to the right of the direction of travel of the vehicle 10. For example, the right-side first road surface information may be information relating to the operation of the vehicle 10 that reflects the road surface condition of the right-side first road surface. For example, the left-side first road surface information and the right-side first road surface information may be at least one or more combinations of the following: vehicle speed, wheel speed, steering angle, yaw rate, accelerator opening, brake operation signal, brake operation amount, brake fluid pressure, longitudinal acceleration, lateral acceleration, engine speed, throttle opening, engine torque, turbine speed, transmission gear ratio, differential limiting clutch engagement torque, driver steering force, and electric power steering assist force.

[0079] The contact-type detection unit 110 can estimate the left-side first road surface friction coefficient μ1L and the right-side first road surface friction coefficient μ1R using the method for estimating the first road surface friction coefficient μ1 when the driving state is a deceleration state, as described above. The contact-type detection unit 110 detects left-side first road surface information and right-side first road surface information from, for example, the wheel speed sensors of the two-wheel drive wheels. For example, the contact-type detection unit 110 detects the left front wheel speed, right front wheel speed, left rear wheel speed, and right rear wheel speed from the wheel speed sensors of the two-wheel drive wheels. Then, the contact-type detection unit 110 estimates the left-side first road surface friction coefficient μ1L based on the left front wheel speed and left rear wheel speed, and estimates the right-side first road surface friction coefficient μ1R based on the right front wheel speed and right rear wheel speed. The contact-type detection unit 110 may, for example, detect left-side first road surface information and right-side first road surface information from the wheel speed sensors of the four-wheel drive wheels.

[0080] The non-contact detection unit 120 detects the left-side second road surface information and the right-side second road surface information of the second road surface in a non-contact manner as road surface conditions of the second road surface. The left-side second road surface information is information that is directly or indirectly related to the road surface condition of the left-side second road surface, which is the road surface to the left of the direction of travel of the vehicle 10. For example, the left-side second road surface information may be information about the state of the left-side second road surface that reflects the road surface condition of the left-side second road surface. The right-side second road surface information is information that is directly or indirectly related to the road surface condition of the right-side second road surface, which is the road surface to the right of the direction of travel of the vehicle 10. For example, the right-side second road surface information may be information about the state of the right-side second road surface that reflects the road surface condition of the right-side second road surface. For example, the left-side second road surface information and the right-side second road surface information may be at least one or more combinations of the following: an image of the area in front of the vehicle 10, ambient temperature, road surface temperature, road surface unevenness, road surface moisture content, and the roughness of the road surface in front of the vehicle 10.

[0081] The non-contact detection unit 120 detects left-side second road surface information and right-side second road surface information from two locations on the left-side second road surface and the right-side second road surface, for example, using a camera that images the area in front of the vehicle 10, a road surface temperature sensor, a near-infrared sensor, or a laser light sensor. The left-side second road surface and the right-side second road surface are scanned using one of the sensors selected from the camera that images the area in front of the vehicle 10, the road surface temperature sensor, the near-infrared sensor, or the laser light sensor. Note that the number of sensors used for scanning is not limited to one; for example, multiple sensors of the same type or multiple sensors of different types may be used. Furthermore, based on the detected left-side second road surface information and right-side second road surface information, the non-contact detection unit 120 determines whether the road surface condition of the left-side second road surface and the right-side second road surface is "DRY", "WET", "SNOW", or "ICE". The non-contact detection unit 120 then estimates the left-side second road surface friction coefficient μ2L and the right-side second road surface friction coefficient μ2R according to the condition of the road surface.

[0082] Next, the control unit 100 according to the second embodiment includes, similar to the components of the control unit 100 according to the first embodiment, an information acquisition unit 300, a road surface condition determination unit 302, a road surface friction coefficient setting unit 304, an upper limit driving force setting unit 306, and a driving force control unit 308.

[0083] Here, in explaining the functional configuration of the control unit 100 of the vehicle 10 according to the second embodiment, Figure 5 will be used as necessary. Figure 5 is a diagram illustrating the control of the vehicle 10 according to the second embodiment. Figure 5 shows four patterns of combinations of road surface conditions for the left first road surface, left second road surface, right first road surface, and right second road surface, and will explain how the control unit 100 performs control processing in each pattern. The four patterns are: (a) the right side has the same type of road surface condition (high μ road - high μ road), and the left side has the same type of road surface condition (low μ road - low μ road); (b) the right side has the same type of road surface condition (low μ road - low μ road), and the left side has a different type of road surface condition (high μ road - low μ road). Furthermore, the four patterns are: (c) the right side has different types of road surface conditions (low μ road - high μ road), and the left side has the same type of road surface conditions (high μ road - high μ road); and (d) the right side has different types of road surface conditions (high μ road - low μ road), and the left side has different types of road surface conditions (low μ road - high μ road). In the four patterns, the part before the "-" indicates the road surface condition of the first road surface, and the part after the "-" indicates the road surface condition of the second road surface. Also, in the explanation of Figure 5, the right side refers to the right side in the direction of vehicle travel, and the left side refers to the left side in the direction of vehicle travel.

[0084] The information acquisition unit 300 acquires, for example, left-side first road surface information, right-side first road surface information, left-side first road surface friction coefficient μ1L, and right-side first road surface friction coefficient μ1R detected by the contact-type detection unit 110. The information acquisition unit 300 also acquires, for example, left-side second road surface information, right-side second road surface information, information representing the road surface condition of the left-side second road surface, information representing the road surface condition of the right-side second road surface, left-side second road surface friction coefficient μ2L, and right-side second road surface friction coefficient μ2R detected by the non-contact-type detection unit 120.

[0085] The road surface condition determination unit 302 determines, for example, whether the road surface condition of the left first road surface and the road surface condition of the left second road surface are of the same type, based on the left first road surface friction coefficient μ1L and the left second road surface friction coefficient μ2L. The road surface condition determination unit 302 also determines, for example, whether the road surface condition of the right first road surface and the road surface condition of the right second road surface are of the same type, based on the right first road surface friction coefficient μ1R and the right second road surface friction coefficient μ2R.

[0086] For example, the road surface condition determination unit 302 determines whether the left-side first road surface friction coefficient μ1L is above a predetermined threshold and whether the road surface condition of the left-side first road surface is high-μ or low-μ. Similarly, the road surface condition determination unit 302 determines whether the road surface condition of the left-side second road surface, the right-side first road surface, or the right-side second road surface is high-μ or low-μ based on the left-side second road surface friction coefficient μ2L, the right-side first road surface friction coefficient μ1R, or the right-side second road surface friction coefficient μ2R. Subsequently, the road surface condition determination unit 302 determines whether the left-side first road surface and the left-side second road surface are of the same type of road surface condition, and whether the right-side first road surface and the right-side second road surface are of the same type of road surface condition. For example, the road surface condition determination unit 302 determines that the road surface conditions are of the same type in the case shown for both sides of the road surface in Figure 5(a), the right-side road surface in Figure 5(b), and the left-side road surface in Figure 5(c). Furthermore, the road surface condition determination unit 302 determines that the road surface conditions are different in the cases shown for the left road surface in Figure 5(b), the right road surface in Figure 5(c), and the road surfaces on both sides in Figure 5(d).

[0087] As described above, the road surface condition determination unit 302 determines, based on the left-side first road surface information and the left-side second road surface information, whether the road surface condition of the left-side first road surface and the road surface condition of the left-side second road surface are of the same type. In addition, the road surface condition determination unit 302 determines, based on the right-side first road surface information and the right-side second road surface information, whether the road surface condition of the right-side first road surface and the road surface condition of the right-side second road surface are of the same type.

[0088] Furthermore, the road surface condition determination unit 302 determines, for example, whether the road surface condition of the left-side first road surface is better than that of the left-side second road surface, and whether the road surface condition of the right-side first road surface is better than that of the right-side second road surface. For example, as shown on the left-side road surface in Figure 5(b), if the road surface condition of the left-side first road surface is a high-μ road surface and the road surface condition of the left-side second road surface is a low-μ road surface, the road surface condition determination unit 302 determines that the road surface condition of the left-side first road surface is better than that of the left-side second road surface. Also, for example, as shown on the right-side road surface in Figure 5(d), if the road surface condition of the right-side first road surface is a high-μ road surface and the road surface condition of the right-side second road surface is a low-μ road surface, the road surface condition determination unit 302 determines that the road surface condition of the right-side first road surface is better than that of the right-side second road surface. Furthermore, the road surface condition determination unit 302 determines, for example, as shown in the left road surface of Figure 5(d), that if the road surface condition of the left first road surface is low μ and the road surface condition of the left second road surface is high μ, then the road surface condition determination unit 302 determines that the road surface condition of the left first road surface is worse than that of the left second road surface. Also, the road surface condition determination unit 302 determines, for example, as shown in the right road surface of Figure 5(c), that if the road surface condition of the right first road surface is low μ and the road surface condition of the right second road surface is high μ, then the road surface condition determination unit 302 determines that the road surface condition of the right first road surface is worse than that of the right second road surface.

[0089] Next, the road surface friction coefficient setting unit 304 sets, for example, the left-side first road surface friction coefficient μ1L for the left-side first road surface, and the right-side first road surface friction coefficient μ1R for the right-side first road surface. Furthermore, the road surface friction coefficient setting unit 304 sets, for example, the left-side second road surface friction coefficient μ2L for the left-side second road surface, and the right-side second road surface friction coefficient μ2R for the right-side second road surface.

[0090] Furthermore, the road surface friction coefficient setting unit 304, for example, in the case of the left road surface in Figure 5(a) and the left road surface in Figure 5(c), sets the road surface friction coefficient μ of the left first road surface to the left first road surface friction coefficient μ1L estimated from the left first road surface information. At the same time, the road surface friction coefficient setting unit 304 also sets the road surface friction coefficient μ of the left second road surface to the same left first road surface friction coefficient μ1L. In this way, if the road surface friction coefficient setting unit 304 determines, for example, that the road surface conditions of the left first road surface and the left second road surface are of the same type, it sets the road surface friction coefficient μ for the left second road surface to the left first road surface friction coefficient μ1L instead of the left second road surface friction coefficient μ2L. Furthermore, the road surface friction coefficient setting unit 304, for example, in the case of the right-side road surface in Figure 5(a) and the right-side road surface in Figure 5(b), sets the road surface friction coefficient μ of the right-side first road surface to the right-side first road surface friction coefficient μ1R estimated from the right-side first road surface information. At the same time, the road surface friction coefficient setting unit 304 also sets the road surface friction coefficient μ of the right-side second road surface to the same right-side first road surface friction coefficient μ1R. In this way, if the road surface friction coefficient setting unit 304 determines, for example, that the road surface conditions of the right-side first road surface and the right-side second road surface are of the same type, it sets the road surface friction coefficient μ for the right-side second road surface to the right-side first road surface friction coefficient μ1R instead of the right-side second road surface friction coefficient μ2R.

[0091] On the other hand, the road surface friction coefficient setting unit 304, for example, in the case of the left road surface in Figure 5(b) and the left road surface in Figure 5(d), sets the road surface friction coefficient μ of the left first road surface to the left first road surface friction coefficient μ1L estimated from the left first road surface information. At the same time, the road surface friction coefficient setting unit 304 sets the road surface friction coefficient μ of the left second road surface to the left second road surface friction coefficient μ2L estimated from the left second road surface information. In this way, if the road surface friction coefficient setting unit 304 determines, for example, that the road surface conditions of the left first road surface and the left second road surface are of different types, it uses the left second road surface friction coefficient μ2L as is, without changing the road surface friction coefficient μ2L for the left second road surface from the left second road surface friction coefficient μ2L to the left first road surface friction coefficient μ1L. Furthermore, the road surface friction coefficient setting unit 304, for example, in the case of the right-side road surface in Figure 5(c) and the right-side road surface in Figure 5(d), sets the road surface friction coefficient μ of the right-side first road surface to the right-side first road surface friction coefficient μ1R estimated from the right-side first road surface information. At the same time, the road surface friction coefficient setting unit 304 sets the road surface friction coefficient μ of the right-side second road surface to the right-side second road surface friction coefficient μ2R estimated from the right-side second road surface information. In this way, if the road surface friction coefficient setting unit 304 determines, for example, that the road surface conditions of the right-side first road surface and the right-side second road surface are of different types, it uses the right-side second road surface friction coefficient μ2R as is, without changing the right-side second road surface friction coefficient μ2R to the right-side first road surface friction coefficient μ1R.

[0092] The upper limit driving force setting unit 306 calculates the upper limit driving force of the left drive wheel using, for example, the road surface friction coefficient μ set for the left second road surface, and calculates the upper limit driving force of the right drive wheel using the road surface friction coefficient μ set for the right second road surface. Then, the upper limit driving force setting unit 306 sets the upper limit driving force used to control the driving force of the left drive wheel to the calculated upper limit driving force of the left drive wheel, and sets the upper limit driving force used to control the driving force of the right drive wheel to the calculated upper limit driving force of the right drive wheel.

[0093] Furthermore, the upper limit driving force setting unit 306 calculates the upper limit driving force of the left drive wheel using the road surface friction coefficient μ set for the left first road surface, for example, as shown in the left road surface in Figure 5(d). The upper limit driving force setting unit 306 then sets the upper limit driving force used to control the driving force of the left drive wheel to the upper limit driving force of the left drive wheel calculated thereto. In this way, if the upper limit driving force setting unit 306 determines, for example, that the road surface condition of the left first road surface is worse than that of the left second road surface, it calculates the upper limit driving force of the left drive wheel using the left first road surface friction coefficient μ1L set for the left first road surface with the worse road surface condition. Furthermore, the upper limit driving force setting unit 306 calculates the upper limit driving force of the right drive wheel using the road surface friction coefficient μ set for the right first road surface, for example, as shown in the right road surface in Figure 5(c). Then, the upper limit driving force setting unit 306 sets the upper limit driving force used to control the driving force of the right drive wheel to the calculated upper limit driving force of the right drive wheel. In this way, if the upper limit driving force setting unit 306 determines, for example, that the road surface condition of the right first road surface is worse than that of the right second road surface, it calculates the upper limit driving force of the right drive wheel using the right first road surface friction coefficient μ1R that is set for the right first road surface with the worse road surface condition.

[0094] The drive force control unit 308 controls the overall drive force of the vehicle 10 based on the upper limit drive force of the left drive wheel and the right drive wheel, which are set by the upper limit drive force setting unit 306. For example, the drive force control unit 308 controls the vehicle 10 by setting the lower of the upper limit drive force of the left drive wheel and the upper limit drive force of the right drive wheel as the overall upper limit drive force of the vehicle 10. However, it is not limited to this, and the drive force control unit 308 may, for example, make the drive forces of the left and right drive wheels different if the input drive force exceeds the lower of the upper limit drive force of the left drive wheel and the upper limit drive force of the right drive wheel, thereby controlling the overall drive force of the vehicle 10. For example, in this case, the drive force control unit 308 may set the drive force of the drive wheel that exceeded the upper limit drive force to the upper limit drive force, and add the difference between the input drive force and the said upper limit drive force to the drive force of the other drive wheel, thereby controlling the overall drive force of the vehicle 10.

[0095] Thus, in the second embodiment, when the road surface condition of the left first road surface and the road surface condition of the left second road surface are of the same type, the control unit 100 calculates the upper limit driving force of the left drive wheel by using the left first road surface friction coefficient μ1L instead of the left second road surface friction coefficient μ2L as the road surface friction coefficient μ of the left second road surface. Furthermore, in the second embodiment, when the road surface condition of the right first road surface and the road surface condition of the right second road surface are of the same type, the control unit 100 calculates the upper limit driving force of the right drive wheel by using the right first road surface friction coefficient μ1R instead of the right second road surface friction coefficient μ2R as the road surface friction coefficient μ of the right second road surface.

[0096] Furthermore, in the second embodiment, the control unit 100 calculates the upper limit driving force of the left drive wheel using the left second road surface friction coefficient μ2L as the road surface friction coefficient μ of the left second road surface when the road surface conditions of the left first road surface and the road surface conditions of the left second road surface are of different types. Furthermore, in the second embodiment, the control unit 100 calculates the upper limit driving force of the right drive wheel using the right second road surface friction coefficient μ2R as the road surface friction coefficient μ of the right second road surface when the road surface conditions of the right first road surface and the road surface conditions of the right second road surface are of different types.

[0097] Furthermore, in the second embodiment, the control unit 100 calculates the upper limit driving force of the left drive wheel when the road surface condition of the left first road surface and the road surface condition of the left second road surface are of different types, and the road surface condition of the left first road surface is worse than that of the left second road surface. Furthermore, in the second embodiment, the control unit 100 calculates the upper limit driving force of the right drive wheel when the road surface condition of the right first road surface and the road surface condition of the right second road surface are of different types, and the road surface condition of the right first road surface is worse than that of the right second road surface.

[0098] As described above, according to the second embodiment, when the road surface conditions of the first and second road surfaces are split road surfaces with different conditions on the left and right sides, it is determined whether the road surface conditions on the left and right sides are of the same type. This makes it possible to appropriately determine whether the road surface conditions are the same even when the road surface conditions differ on the left and right sides.

[0099] Furthermore, according to the second embodiment, the road surface conditions of the first and second road surfaces are determined on both the left and right sides, and different road surface friction coefficients μ are applied according to the results to set the upper limit driving force for each of the left and right drive wheels. This makes it possible to accurately calculate the upper limit driving force for the left and right drive wheels on a split road surface, and to control the driving force of the vehicle 10 more optimally.

[0100] Embodiments of the present invention have been described above with reference to the attached drawings, but it goes without saying that the present invention is not limited to these embodiments. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention.

[0101] For example, in the above embodiment, the first road surface friction coefficient estimation unit 114, the second road surface friction coefficient estimation unit 124, and the third road surface friction coefficient estimation unit 134 were described as being included in the contact-type detection unit 110, the non-contact-type detection unit 120, and the external information detection unit 130, respectively, but the system is not limited to such examples. The first road surface friction coefficient estimation unit 114, the second road surface friction coefficient estimation unit 124, and the third road surface friction coefficient estimation unit 134 may be included in the control unit 100, for example.

[0102] The series of processes according to the above-described embodiment may be implemented using software, hardware, or a combination of software and hardware. The program constituting the software is pre-stored in, for example, a non-transitory storage medium provided inside or outside each device. The program is then read from, for example, the non-transitory storage medium (e.g., ROM) to a temporary storage medium (e.g., RAM) and executed by a processor such as a CPU.

[0103] Furthermore, according to the above-described embodiment, a program for executing the processing of each function of the control unit 100 can be provided. In addition, a non-temporary recording medium that can be read by a computer and on which the program is stored can also be provided. The non-temporary recording medium may be a disk-type recording medium such as an optical disk, magnetic disk, or magneto-optical disk, or it may be a semiconductor memory such as a flash memory or USB memory. [Explanation of Symbols]

[0104] 1. Vehicle control system 10 vehicles 20 Information distribution device 30 Networks 100 Control Unit 102 processors 104 memory 110 Contact-type detection unit (first detection unit) 120 Non-contact detection unit (second detection unit) 132 External Information Receiving Unit

Claims

1. A first detection unit detects first road surface information relating to the road surface condition of the first road surface, which is the road surface at the current position where the vehicle's drive wheels are in contact, A second detection unit detects second road surface information relating to the road surface condition of a second road surface located in front of the vehicle in a non-contact manner, A control unit that controls the driving force of the vehicle using a road surface friction coefficient estimated from at least one of the first road surface information and the second road surface information, Equipped with, The first detection unit detects, as the road surface conditions of the first road surface, left-side first road surface information relating to the road surface condition of the left-side first road surface, which is the road surface to the left of the direction of travel of the vehicle, and right-side first road surface information relating to the road surface condition of the right-side first road surface, which is the road surface to the right of the direction of travel of the vehicle. The second detection unit detects, in a non-contact manner, the road surface conditions of the second road surface, specifically the left-side second road surface, which is the road surface to the left of the vehicle's direction of travel, and the right-side second road surface, which is the road surface to the right of the vehicle's direction of travel. The control unit comprises one or more processors and one or more memories connected to the processors. The aforementioned processor, Based on the first road surface information and the second road surface information, it is determined whether the road surface condition of the first road surface and the road surface condition of the second road surface are of the same type. When the road surface conditions of the first road surface and the road surface conditions of the second road surface are of different types, the driving force of the vehicle is controlled using the second road surface friction coefficient estimated from the second road surface information as the road surface friction coefficient of the second road surface, When the road surface condition of the first road surface and the road surface condition of the second road surface are of the same type, the driving force of the vehicle is controlled by using the first road surface friction coefficient estimated from the first road surface information instead of the second road surface friction coefficient. Using the road surface friction coefficients of the left and right sides, the upper limits of the driving force of the left and right drive wheels are calculated independently to control the driving force of the vehicle. Using the left-side first road surface information and the left-side second road surface information, the left-side upper limit driving force is set as the upper limit driving force of the left-side drive wheel of the vehicle, Using the aforementioned right-side first road surface information and the aforementioned right-side second road surface information, the right-side upper limit driving force is set as the upper limit driving force of the right-side drive wheel of the vehicle, The lower of the left-side upper limit driving force and the right-side upper limit driving force is set as the overall upper limit driving force of the vehicle, thereby setting the overall upper limit driving force. If the requested driving force input by the driver exceeds the overall upper limit driving force, the driving force of the drive wheel on the side set to the upper limit driving force corresponding to the overall upper limit driving force is limited to or less than the overall upper limit driving force, and the difference between the requested driving force and the overall upper limit driving force is added to the driving force of the other drive wheel. A vehicle that performs a process that includes the following.

2. A first detection unit detects first road surface information relating to the road surface condition of the first road surface, which is the road surface at the current position where the vehicle's drive wheels are in contact, A second detection unit detects second road surface information relating to the road surface condition of a second road surface located in front of the vehicle in a non-contact manner, An external information receiving unit receives a third road surface information relating to the road surface condition of the third road surface, which is the road surface located in front of the vehicle and includes the second road surface, from an information distribution device connected to the vehicle via a network. A control unit that controls the driving force of the vehicle using a road surface friction coefficient estimated from at least one of the first road surface information and the second road surface information, Equipped with, The control unit comprises one or more processors and one or more memories connected to the processors. The aforementioned processor, Based on the first road surface information and the second road surface information, it is determined whether the road surface condition of the first road surface and the road surface condition of the second road surface are of the same type. If the second detection unit cannot detect the second road surface information, the system determines, based on the third road surface information, whether the road surface condition of the first road surface and the road surface condition of the second road surface are of the same type, as road surface information relating to the road surface condition of the second road surface. When the road surface conditions of the first road surface and the road surface conditions of the second road surface are of different types, the driving force of the vehicle is controlled using the second road surface friction coefficient estimated from the second road surface information as the road surface friction coefficient of the second road surface, When the road surface condition of the first road surface and the road surface condition of the second road surface are of the same type, the driving force of the vehicle is controlled by using the first road surface friction coefficient estimated from the first road surface information instead of the second road surface friction coefficient. A vehicle that performs a process that includes the following.

3. The aforementioned processor, When the road surface conditions of the first road surface and the road surface conditions of the second road surface are of different types, and the road surface condition of the first road surface is better than the road surface condition of the second road surface, the driving force of the vehicle is controlled using the second road surface friction coefficient as the road surface friction coefficient of the second road surface. The vehicle according to claim 1 or 2, wherein, when the road surface condition of the first road surface and the road surface condition of the second road surface are of different types, and the road surface condition of the first road surface is worse than the road surface condition of the second road surface, the driving force of the vehicle is controlled using the first road surface friction coefficient as the road surface friction coefficient of the first road surface.

4. The processor is Based on the left-side first road surface information and the left-side second road surface information, it is determined whether the road surface condition of the left-side first road surface and the road surface condition of the left-side second road surface are of the same type, and based on the right-side first road surface information and the right-side second road surface information, it is determined whether the road surface condition of the right-side first road surface and the road surface condition of the right-side second road surface are of the same type. When the road surface condition of the left-side first road surface and the road surface condition of the left-side second road surface are of the same type, the upper limit of the driving force of the left-side drive wheel is calculated by using the left-side first road surface friction coefficient estimated from the left-side first road surface information, instead of the left-side second road surface friction coefficient estimated from the left-side second road surface information, The vehicle according to claim 1, wherein, when the road surface condition of the right first road surface and the road surface condition of the right second road surface are of the same type, the upper limit of the driving force of the right drive wheel is calculated by using the right first road surface friction coefficient estimated from the right first road surface information as the road surface friction coefficient of the right second road surface, instead of the right second road surface friction coefficient estimated from the right second road surface information.

5. The vehicle further includes an external information receiving unit that receives external information regarding the road surface condition of the second road surface from an information distribution device connected to the vehicle via a network, The vehicle according to claim 1, wherein, when the second detection unit cannot detect the second road surface information, the processor controls the driving force of the vehicle by using the external information as road surface information relating to the road surface condition of the second road surface.

Images