Vehicle control device, vehicle control program, and vehicle control method

Abstract

A vehicle control device (300) comprises: a reference target torque estimation unit (302) that estimates, on the basis of vehicle information, a reference target torque for causing a following vehicle (100) following a preceding vehicle to travel when the traveling state of the following vehicle meets a specific criterion; and a target inter-vehicle distance calculation unit (303) that, when the inter-vehicle distance from the preceding vehicle to the following vehicle is changed on the basis of the reference target torque, calculates, as a target inter-vehicle distance, a corresponding inter-vehicle distance, which corresponds to a value within a specific range including the minimum value among the actual values of torque generated on the basis of the reference target torque.

Description

Vehicle control device, vehicle control program, and vehicle control method CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on and claims the benefit of priority from patent application serial number 2024-151387, filed September 3, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a vehicle control device, a vehicle control program, and a vehicle control method.

[0003] The conventional technology disclosed in Patent Document 1 calculates the rate of change in air resistance based on a reference torque and an actual torque, and causes vehicles to travel in a convoy at a distance that satisfies a target rate of change in air resistance.

[0004] Japanese Patent Application Laid-Open No. 2021-059131

[0005] The torque (MG torque) generated by the rotating electric machine of the following vehicle can vary depending on the driving conditions of the following vehicle, such as vehicle speed, acceleration / deceleration, road gradient, and vehicle weight. Therefore, when these driving conditions change, the inter-vehicle distance calculated based on the MG torque can also vary. Therefore, even if the air resistance increase / decrease rate meets the target value, it does not necessarily mean that the following vehicle is driving at an inter-vehicle distance where the driving resistance is minimum or close to minimum. As such, as a result of detailed studies by the inventors, it was found that the conventional technology has a problem in that there is room for improvement in terms of reducing the driving energy consumption of the following vehicle following the leading vehicle.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a vehicle control device, a vehicle control program, and a vehicle control method that suppress the consumption of traveling energy by a following vehicle.

[0007] In order to achieve the above-mentioned object, the vehicle control device of the present disclosure includes a reference target torque estimation unit that estimates, based on vehicle information, a reference target torque for causing a following vehicle following a leading vehicle to travel when the traveling state of the following vehicle satisfies specific conditions, and a target inter-vehicle distance calculation unit that, based on the reference target torque, calculates, as a target inter-vehicle distance, a corresponding inter-vehicle distance that corresponds to a value within a specific range including the minimum value of the actual torque generated based on the reference target torque when the inter-vehicle distance from the leading vehicle to the following vehicle is changed.

[0008] The vehicle control program of the present disclosure causes at least one processor to execute processing that includes estimating, based on vehicle information, a standard target torque for causing a following vehicle following a leading vehicle to travel when the traveling state of the following vehicle satisfies specific conditions, and calculating, based on the standard target torque, a corresponding inter-vehicle distance that corresponds to a value within a specific range including the minimum value of the actual torque generated based on the standard target torque when the inter-vehicle distance from the leading vehicle to the following vehicle is changed.

[0009] The vehicle control method disclosed herein executes processing in which at least one processor estimates, based on vehicle information, a reference target torque for causing a following vehicle following a leading vehicle to travel when the traveling state of the following vehicle satisfies a specific condition, and, based on the reference target torque, calculates, as a target following vehicle distance, a corresponding following vehicle distance that corresponds to a value within a specific range including the minimum value of the actual torque generated based on the reference target torque when the following vehicle distance from the leading vehicle to the following vehicle is changed.

[0010] According to the present disclosure, it is possible to reduce the consumption of energy required for driving by a following vehicle.

[0011] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. In the drawings, FIG. 1 is a diagram illustrating a vehicle equipped with a vehicle control device 300 according to an embodiment of the present disclosure. FIG. 2 is a diagram illustrating a hardware configuration of the vehicle control device 300 according to an embodiment of the present disclosure. FIG. 3 is a diagram illustrating functional blocks of the vehicle control device 300 according to an embodiment of the present disclosure. FIG. 4A is a diagram illustrating an inter-vehicle distance corresponding to a minimum actual torque. FIG. 4B is a diagram illustrating an inter-vehicle distance corresponding to a minimum actual torque. FIG. 4C is a diagram illustrating an inter-vehicle distance corresponding to a minimum actual torque. FIG. 4D is a diagram illustrating an inter-vehicle distance corresponding to a minimum actual torque. FIG. 4E is a diagram illustrating an inter-vehicle distance corresponding to a minimum actual torque. FIG. 5A is a diagram illustrating a method for calculating a torque difference correction amount. FIG. 5B is a diagram illustrating a method for calculating a torque difference correction amount. FIG. 5C is a diagram illustrating a method for calculating a torque difference correction amount. FIG. 5D is a diagram illustrating a method for calculating a torque difference correction amount. FIG. 5E is a diagram illustrating a method for calculating a torque difference correction amount. FIG. 6 is a diagram illustrating a method by which the target inter-vehicle distance calculation unit 303 sets an initial inter-vehicle distance value. FIG. 7 is a diagram illustrating a method by which the target inter-vehicle distance calculation unit 303 calculates a target inter-vehicle distance. FIG. 8 is a flowchart illustrating an example of an operation for determining whether or not to execute low air resistance search control. FIG. 9 is a flowchart illustrating an example of an operation for estimating MG torque when a reference condition is satisfied. FIG. 10 is a flowchart illustrating an example of an operation of low air resistance search control in step S24 of FIG. 9. FIG. 11 is a timing chart illustrating an example of an operation of low air resistance search control by the vehicle control device 300. FIG. 12 is a timing chart illustrating an example of an operation of low air resistance search control by the vehicle control device 300 when a cutting-in vehicle occurs. FIG. 13A is a diagram illustrating an example of a lateral deviation amount in step S8 of FIG. 8. FIG. 13B is a diagram illustrating an example of a lateral deviation amount in step S8 of FIG. 8. FIG. 14 is a diagram illustrating an example of the inter-vehicle distance from the following vehicle to the leading vehicle during low air resistance search control. FIG. 15 is a diagram illustrating a situation in which a cutting-in vehicle occurs.

[0012] Hereinafter, one embodiment of the present disclosure will be described.

[0013] 1 is a diagram illustrating a vehicle equipped with a vehicle control device according to an embodiment of the present disclosure. Vehicle 100 may be interpreted as a vehicle that runs based on a driver's driving operation, and may be interpreted as an electric vehicle that drives the rear wheels and steers the front wheels. Vehicle body 100A of vehicle 100 is the main body of vehicle 100, and is the part referred to as the "body."

[0014] Vehicle 100 may be configured as a so-called "rear-wheel drive" vehicle, or alternatively, as a front-wheel drive vehicle, i.e., a vehicle in which the front wheels are driven and the front wheels are steered. Vehicle 100 may also be configured as a four-wheel drive vehicle, i.e., a vehicle in which the front and rear wheels are driven and the front wheels are steered. In the former case, a separate rotating electric machine 103 for driving the front wheels may be provided instead of rotating electric machine 103 for driving the rear wheels. In the latter case, a separate rotating electric machine 103 for driving the front wheels may be provided in addition to rotating electric machine 103 for driving the rear wheels.

[0015] The vehicle 100 may include a battery 101, an inverter 102, a rotating electric machine 103, an EPS (Electric Power Steering) 104, a brake ECU (Electronic Control Unit) 105, an ACC (Adaptive Cruise Control) system 106, a drive train 107, a sensor group 200, and a vehicle control device 300. The vehicle control device 300 may be interpreted as an EVC (Electric Vehicle Controller or Electric Vehicle Control Unit).

[0016] The battery 101 may be interpreted as a power storage device including a plurality of cells. The battery 101 may store power to drive the rotating electric machine 103 and may store power regenerated from the rotating electric machine 103. Each of the plurality of cells may be interpreted as a secondary battery such as a lithium ion battery, a nickel-metal hydride battery, or a lithium iron phosphate battery.

[0017] The inverter 102 may be interpreted as a device that controls the rotation of the rotating electric machine 103. The inverter 102 may convert DC power supplied from the battery 101 into AC power in accordance with the torque from the vehicle control device 300, and supply the AC power to the rotating electric machine 103, thereby controlling the rotation of the rotating electric machine 103. One or more inverters 102 may be provided in the vehicle 100.

[0018] The rotating electric machine 103 may be considered as a traction motor that receives power from the battery 101 and generates driving force for rotating the wheels, i.e., driving force (driving torque) necessary for the vehicle 100 to run. One example of the rotating electric machine 103 is a so-called "motor generator" (MG). The driving force generated by the rotating electric machine 103 is transmitted to the wheels via a drive train 107. The drive train 107 may include a driving force transmission system for the rear wheels, tires for the rear wheels, etc.

[0019] The EPS 104 may be considered as a system that assists steering of the steering wheel using an electric motor. The brake ECU 105 may brake each wheel of the vehicle 100 by driving an actuator (not shown) according to the braking amount.

[0020] The sensor group 200 may include a wheel speed sensor 201 , an acceleration sensor 202 , an external sensor 203 , a gradient sensor 204 and an imaging device 205 .

[0021] The wheel speed sensor 201 may be interpreted as a sensor that detects the wheel speed (vehicle speed) of the vehicle 100. The acceleration sensor 202 may be interpreted as a sensor that detects the acceleration and deceleration of the vehicle 100.

[0022] The external sensor 203 may be interpreted as a sensor that detects the surrounding conditions of the vehicle 100. The external sensor 203 may include, for example, an on-board millimeter-wave radar, a camera, an on-board sonar sensor, a LiDAR (Light Detection and Ranging), etc. The external sensor 203 may detect the inter-vehicle distance from the following vehicle to the leading vehicle, and input the detected inter-vehicle distance as vehicle information to the vehicle control device 300. The following vehicle may be interpreted as the vehicle 100 of the present disclosure.

[0023] The gradient sensor 204 is a sensor that detects the gradient of the road surface on which the vehicle 100 is traveling. A signal (detected value) indicating the value of the gradient detected by the gradient sensor 204 may be input to the vehicle control device 300 as vehicle information. The gradient of the road surface may be calculated by the vehicle control device 300. For example, the vehicle control device 300 may calculate the gradient based on the acceleration and deceleration detected by the acceleration sensor 202, the acceleration calculated from the wheel speed detected by the wheel speed sensor 201, etc.

[0024] The imaging device 205 may input captured image data generated by capturing an image of the surroundings of the following vehicle to the vehicle control device 300 as vehicle information.

[0025] The ACC system 106 may be considered to have an adaptive cruise function. The adaptive cruise function may include at least one of a constant speed control that controls the vehicle speed of the following vehicle so that the speed of the following vehicle is equal to or less than a set speed, and a leading vehicle following control that controls the vehicle speed and the distance between the leading vehicle and the following vehicle so that the distance between the leading vehicle and the following vehicle is a set distance.

[0026] (Overview of Vehicle Control Device 300) The vehicle control device 300 may be interpreted as a device that controls the inverter 102. The vehicle control device 300 may control the rotation speed, rotation direction, torque, etc. of the rotating electric machine 103 by controlling the inverter 102.

[0027] In order to estimate and detect the inter-vehicle distance that minimizes air resistance from the MG torque, it is necessary to separately estimate whether the MG torque has changed due to an external disturbance factor or due to the inter-vehicle distance. To address this issue, the vehicle control device 300 may be configured as follows.

[0028] (1) The vehicle control device 300 calculates a target inter-vehicle distance that minimizes the MG torque of the following vehicle by eliminating external disturbance factors. (1_a) Determination of Execution of Low Air Resistance Search Control: The vehicle control device 300 may determine whether to execute the low air resistance search control by determining whether the driving state of the following vehicle following the leading vehicle satisfies specific conditions. Hereinafter, for convenience of explanation, the low air resistance search control may be simply referred to as "search control." The search control may be interpreted as driving control that causes the following vehicle to follow the leading vehicle with low air resistance. Since the search control includes driving control that causes the following vehicle to follow the leading vehicle, it may be interpreted as platooning control. (1_b) Estimation of Reference Target Torque: If the vehicle control device 300 determines that the search control is executable, it may estimate the MG torque when the driving state of the following vehicle following the leading vehicle satisfies specific conditions as the reference target torque (normalized MG torque). (1_c) Calculation of target inter-vehicle distance: The vehicle control device 300 executes search control to slowly change the inter-vehicle distance, i.e., while shortening or widening the inter-vehicle distance, calculates the target inter-vehicle distance at which the reference target torque becomes minimum. The calculated target inter-vehicle distance is transmitted to the ACC system 106.

[0029] In this way, by estimating the reference target torque with external disturbance factors eliminated, the vehicle control device 300 can distinguish, for example, whether the MG torque has been minimized because the vehicle speed simply decreased, or because the inter-vehicle distance has changed. In other words, it is possible to eliminate external disturbance factors and appropriately calculate the target inter-vehicle distance that minimizes the air resistance of the following vehicle.

[0030] (2) The vehicle control device 300 may calculate the target inter-vehicle distance while eliminating the influence on search control due to differences in the shape of the preceding vehicle. (2_a) When the vehicle control device 300 detects that a specific vehicle (cutting in vehicle) has cut in between the preceding vehicle and the following vehicle that it has been following, as shown in Figures 12 and 15, for example, the vehicle control device 300 may reset the reference target torque estimated up to the detection. After the reset, the vehicle control device 300 may regard the cutting in vehicle as a new preceding vehicle, re-estimate the reference target torque for driving the following vehicle when the driving state of the following vehicle following the preceding vehicle satisfies a specific condition, and further perform search control.

[0031] (2_b) When the vehicle control device 300 detects a vehicle that has cut in and then re-executes searching control, the vehicle control device 300 may estimate an initial value of the inter-vehicle distance when starting (resuming) searching control based on the projected area of ​​the inter-vehicle. This initial value may be interpreted as the inter-vehicle distance when starting the process of calculating the corresponding inter-vehicle distance that minimizes the MG torque as the target inter-vehicle distance.

[0032] In this way, the vehicle control device 300 can complete the low air resistance search more quickly by setting the initial value of the inter-vehicle distance when starting search control, taking into account the projected area of ​​the cutting-in vehicle.

[0033] Next, the hardware configuration of the vehicle control device 300 will be described with reference to Fig. 2. Fig. 2 is a diagram showing the hardware configuration of the vehicle control device 300 according to an embodiment of the present disclosure.

[0034] The vehicle control device 300 may include an input / output I / F (Interface) 1, a memory 2, and a processor 3. These may be communicably connected via a bus 4.

[0035] The input / output I / F 1 may be interpreted as an interface for communicating with the on-board device shown in Fig. 1. The on-board device may be interpreted as the inverter 102, the EPS 104, the brake ECU 105, the ACC system 106, the sensor group 200, etc. shown in Fig. 1.

[0036] The input / output I / F 1 may be interpreted as an input / output function based on CAN (Controller Area Network: a registered trademark), a communication protocol defined in ISO 11898-6. The vehicle control device 300 can transmit data between the vehicle control device 300 and the ACC system 106 via CAN communication via the input / output I / F 1. The CAN can connect the vehicle control device 300 and the ACC system 106 via serial wiring, for example, thereby reducing the costs associated with wiring throughout the vehicle 100, specifically, the labor costs of procuring, laying, and replacing wiring. Furthermore, because CAN has a bus topology, employing CAN communication between the vehicle control device 300 and the ACC system 106 allows the ACC system 106 to be easily connected to the vehicle control device 300, and the ACC system 106 can be easily removed from the vehicle control device 300 during maintenance.

[0037] The memory 2 may store a vehicle control program 2a for controlling the rotating electric machine 103, etc. The processor 3 may execute specific processing by expanding the vehicle control program 2a.

[0038] The functions realized by the vehicle control program 2a will be described with reference to Fig. 3. Fig. 3 is a diagram showing functional blocks of a vehicle control device 300 according to an embodiment of the present disclosure.

[0039] The vehicle control device 300 may include a torque calculation unit 301, a reference target torque estimation unit 302, a target inter-vehicle distance calculation unit 303, an inter-vehicle distance transmission unit 304, an execution flag transmission unit 305, and a target torque selection unit 306. These functions may be realized by the processor 3 shown in FIG. 2 executing the vehicle control program 2 a.

[0040] (Torque Calculation Unit 301 ) The torque calculation unit 301 may calculate an accelerator target torque TACL, which is a required torque according to the accelerator operation by the driver, and input the accelerator target torque TACL to the target torque selection unit 306 .

[0041] (Reference target torque estimation unit 302) When the instruction 400a to execute searching control is input, the reference target torque estimation unit 302 may estimate the reference target torque excluding disturbance factors based on the vehicle information at the timing of inputting (receiving) the instruction 400a to execute searching control. The instruction 400a to execute searching control may be output when the driver operates the switch 400.

[0042] The reference target torque estimation unit 302 determines whether the driving condition of the following vehicle following the preceding vehicle satisfies a specific condition, and if the driving condition does not satisfy the specific condition, it may not estimate the reference target torque, but if the driving condition satisfies the specific condition, it may estimate the reference target torque.

[0043] The vehicle information may include an instruction 400a to execute search control, a vehicle-to-vehicle distance, a steering angle, a vehicle speed, a gradient, an actual torque, a lateral deviation amount, a rotation speed of the rotating electric machine 103, a brake torque, and the like.

[0044] The actual torque may be interpreted as the torque generated by the rotating electric machine 103. Because there is a certain correlation between the current flowing through the rotating electric machine 103 and the torque generated by the rotating electric machine 103, the actual torque may be calculated based on the current, the angular velocity of the rotating electric machine 103, etc. The current may become larger when the running resistance is large, and may become smaller when the running resistance is small.

[0045] The amount of lateral deviation may be interpreted as the amount of deviation of the following vehicle relative to the preceding vehicle in the lateral direction, or as the amount of deviation of the following vehicle in the lateral direction from the center of the preceding vehicle in the lateral direction (vehicle width direction).

[0046] The instruction 400a to execute search control may be generated by the display control unit of a specific display panel when a driver operation is performed on an icon set on the display panel, instead of an operation on the switch 400.

[0047] The reference target torque may be interpreted as a target torque for causing a following vehicle following a leading vehicle to travel when the traveling state of the following vehicle satisfies a specific condition.

[0048] The driving conditions satisfying a specific condition may include, for example, at least one of the following: the speed of the following vehicle while traveling on a highway is within a specific speed range; the gradient of the highway road surface is within a specific gradient range; the steering angle of the following vehicle while traveling on a highway is within a specific steering angle range; the acceleration / deceleration of the following vehicle while traveling on a highway is within a specific acceleration / deceleration range; the relative lateral deviation of the following vehicle in the width direction with respect to the preceding vehicle is within a specific range; and the speed difference between the preceding vehicle and the following vehicle is within a specific range.

[0049] Specifically, the driving state satisfying the specific conditions may include at least one of the following conditions (1) to (6): (1) The vehicle speed (Vb) of a following vehicle traveling on a highway or the like is within a specific speed range that can be considered constant, for example, 110 KPH > Vb > 90 KPH. The specific speed range is not limited to this and may include any value from + several percent to - several percent of the current vehicle speed, taking into account vehicle speed detection errors. (2) The acceleration / deceleration (ΔVb) of a following vehicle traveling on a highway is within a specific acceleration / deceleration range that can be considered constant, for example, 0.1 G > ΔVb > -0.1 G. The specific acceleration / deceleration is not limited to this and may include any value from + several percent to - several percent of the current acceleration / deceleration, taking into account acceleration / deceleration detection errors. (3) The gradient (θr) in the pitch direction of the road surface of the highway on which the following vehicle is traveling is within a specific gradient range that can be considered flat, for example, 5% > θr > -5%. The specific gradient range is not limited to these and may include any value between + a few percent and - a few percent of the current gradient, taking into account gradient detection errors. (4) The steering angle (θEPS) of a following vehicle traveling on a highway or the like is within a specific steering angle range in which the following vehicle can be considered to be traveling straight, for example, a steering angle equivalent to 200R to the left > θEPS and a steering angle equivalent to 200R to the right > θEPS. 200R may be interpreted as a radius of curvature of 200. The specific steering angle range is not limited to these and may include a specific radius of curvature that can be considered to be a straight road. (5) The relative lateral deviation amount (ΔZURE) of the following vehicle in the width direction with respect to the preceding vehicle is within a specific range, for example, 0.5 m to the left > ΔZURE and 0.5 m to the right > ΔZURE. The specific range is not limited to these and may include any value between + a few percent and - a few percent of the current lateral deviation amount, taking into account lateral deviation amount detection errors. The amount of lateral deviation may be corrected to zero by the EPS 104, and this corrected amount of deviation may be transmitted as vehicle information from the EPS 104 to the vehicle control device 300 via CAN communication. (6) The speed difference between the leading vehicle and the following vehicle is within a specific range, for example, the speed difference is less than 2 kph.

[0050] The fact that the driving state satisfies the specific conditions may be interpreted as the absence of all or any of the disturbance factors shown in (7) to (12) below. (7) The speed of the following vehicle while driving on an expressway is outside a specific speed range. (8) The gradient of the road surface of the expressway is outside a specific gradient range. (9) The steering angle of the following vehicle while driving on an expressway is outside a specific steering angle range. (10) The acceleration / deceleration of the following vehicle while driving on an expressway is outside a specific acceleration / deceleration range. (11) The amount of lateral deviation of the following vehicle relative to the leading vehicle is outside a specific range. (12) The speed difference between the leading vehicle and the following vehicle is outside a specific range.

[0051] (Another Estimation Example 1 of Reference Target Torque) When the reference target torque estimation unit 302 detects that a specific vehicle has cut in between the leading vehicle and the following vehicle while the following vehicle is performing cruise control to follow the leading vehicle while maintaining the corresponding inter-vehicle distance, the reference target torque estimation unit 302 may reset the reference target torque that has been estimated up to that point. After resetting the reference target torque, the reference target torque estimation unit 302 may regard the specific vehicle as the leading vehicle and re-estimate the reference target torque at which the following vehicle will travel when the traveling state of the following vehicle following the leading vehicle satisfies a specific condition. Details of the corresponding inter-vehicle distance will be described later.

[0052] With this configuration, even if the size (projected area) of the cutting-in vehicle is different from the size of the preceding vehicle before the cutting-in occurred, the cutting-in vehicle can be considered as a new preceding vehicle, and a reference target torque can be estimated that will result in a vehicle-to-vehicle distance that will result in the following vehicle's consumption of driving energy being close to a minimum.

[0053] (Another example 2 of estimating the reference target torque) The calculation period in which the reference target torque estimation unit 302 estimates the reference target torque when the above-mentioned specific conditions are satisfied may be shorter than the calculation period in which the target inter-vehicle distance calculation unit 303 calculates the corresponding inter-vehicle distance as the target inter-vehicle distance.

[0054] This configuration can prevent mutual interference between the calculation timings of the reference target torque estimation unit 302 and the target inter-vehicle distance calculation unit 303.

[0055] (Another example 3 of estimating reference target torque) The reference target torque estimation unit 302 calculates one or more torque difference correction amounts (ΔT) to correct the error (MG torque difference) caused by the difference between the current driving conditions (driving state) and the specific conditions described above, and may correct the target torque (MG target torque TMG) ​​of the rotating electric machine 103 for driving the following vehicle by the torque difference correction amount (ΔT), and input the corrected torque to the target inter-vehicle distance calculation unit 303 as the reference target torque.

[0056] Specifically, the reference target torque estimation unit 302 may calculate a plurality of torque difference correction amounts (ΔT) by the calculations shown in equations (20) to (24). ΔT (vehicle speed difference) = LPF1 {MAP1 (Vb)} (20) ΔT (acceleration / deceleration difference) = LPF2 {MAP2 (ΔVb)} (21) ΔT (gradient difference) = LPF3 {MAP3 (θr)} (22) ΔT (steering angle difference) = LPF4 {MAP4 (θEPS)} (23) ΔT (deviation amount difference) = LPF5 {MAP5 (ΔZURE)} (24)

[0057] LPF* in each equation represents a smoothing operation using a first-order low-pass filter. The time constant for the operation of equation (20) may be, for example, 1 s. The time constant for the operation of equation (21) may be, for example, 0.1 s. The time constant for the operation of equation (22) may be, for example, 0.5 s. The time constant for the operation of equations (23) and (24) may be, for example, 1.0 s.

[0058] MAP1 (Vb) in equation (20) may be interpreted as a MAP1 value corresponding to the difference between the current vehicle speed and the reference speed, as shown in FIG. 5A, or as a rolling resistance difference. MAP2 (Vb) in equation (21) may be interpreted as a MAP2 value corresponding to the acceleration / deceleration difference between the current acceleration / deceleration and the reference acceleration / deceleration, as shown in FIG. 5B. MAP3 (Vb) in equation (22) may be interpreted as a MAP3 value corresponding to the gradient difference between the current gradient and the reference gradient, as shown in FIG. 5C. MAP4 (Vb) in equation (23) may be interpreted as a MAP4 value corresponding to the steering angle difference between the current steering angle and the reference steering angle, as shown in FIG. 5D. MAP5 (Vb) in equation (24) may be interpreted as a MAP5 value corresponding to the deviation difference between the current deviation amount and the reference deviation amount, as shown in FIG. 5E.

[0059] The reference target torque estimation unit 302 may calculate the reference target torque by the calculation shown in equation (25): Reference target torque=TMG+ΔT (vehicle speed difference)+ΔT (acceleration / deceleration difference)+ΔT (gradient difference)+ΔT (steering angle difference)+ΔT (deviation amount difference) (25)

[0060] By calculating equations (20) to (25), it is possible to estimate the MG torque without the influence of the above-mentioned disturbance factors (vehicle speed, road gradient, acceleration / deceleration, steering angle, etc.).

[0061] (Target Inter-Vehicle Distance Calculation Unit 303) When the inter-vehicle distance from the leading vehicle to the following vehicle is changed based on the reference target torque, the target inter-vehicle distance calculation unit 303 may calculate, as the target inter-vehicle distance, a corresponding inter-vehicle distance that corresponds to a value within a specific range including the minimum value of the actual torque generated based on the reference target torque. Changing the inter-vehicle distance may be interpreted as gradually shortening the inter-vehicle distance, gradually widening the inter-vehicle distance, or repeatedly shortening and widening the inter-vehicle distance.

[0062] The target inter-vehicle distance calculation unit 303 calculates this corresponding inter-vehicle distance as the target inter-vehicle distance and transmits information on the calculated target inter-vehicle distance to the ACC system 106, for example, by CAN communication. The ACC system 106 that receives the target inter-vehicle distance may calculate a target torque (ACC target torque TACC) so that the current inter-vehicle distance matches the target inter-vehicle distance.

[0063] (Regarding the Corresponding Inter-Vehicle Distance) The corresponding inter-vehicle distance may be interpreted as the inter-vehicle distance corresponding to the actual torque generated based on the reference target torque within a specific range including the minimum value (minimum torque), as shown in, for example, FIGS. 4A to 4E . These figures show the actual torque that changes depending on the inter-vehicle distance. The vertical axis represents the actual torque, and the horizontal axis represents the inter-vehicle distance. These figures show the minimum value of the actual torque, the actual torque within a specific range including the minimum value, and the like. The specific range may be interpreted as a certain range from the inter-vehicle distance corresponding to the minimum value of the actual torque. For example, if the inter-vehicle distance is 30 m, the certain range may be interpreted as a distance equivalent to X% of 30 m (e.g., ±3 m). X% may include any value ranging from several percent to several tens of percent, taking into account errors in the detection accuracy of the external sensor 203 and the detection accuracy of the actual torque. The actual torque within the specific range may include the minimum value of the actual torque, an actual torque that can be considered equivalent to this minimum value, and the like. Specifically, the actual torque within the specific range may include the minimum actual torque, the actual torque next to the minimum actual torque, and so on.

[0064] For example, the corresponding inter-vehicle distance may be interpreted as the inter-vehicle distance corresponding to the minimum actual torque as shown in Figures 4A and 4B, or as the inter-vehicle distance corresponding to the actual torque next to the minimum actual torque. When there are multiple minimum actual torques with the same value as shown in Figure 4E, the corresponding inter-vehicle distance may be interpreted as the inter-vehicle distance corresponding to any one of these actual torques. When there are multiple minimum actual torques with the same value, the corresponding inter-vehicle distance may be interpreted as the inter-vehicle distance corresponding to the value of these actual torques that corresponds to the position where the following vehicle is farthest from the leading vehicle.

[0065] (Specific Example 1 of Calculating Target Inter-Vehicle Distance) When there is one value when the actual torque changes from decreasing to increasing (for example, the actual torque indicated by the dashed line in FIG. 4C ), the target inter-vehicle distance calculation unit 303 may set this value as a value within a specific range and calculate the corresponding inter-vehicle distance as the target inter-vehicle distance. This makes it possible to set an inter-vehicle distance that minimizes the driving energy consumption of the following vehicle.

[0066] (Specific Example 2 of Calculating Target Inter-Vehicle Distance) When there are multiple values ​​at which the actual torque changes from decreasing to increasing (for example, the two actual torques indicated by the dashed lines in FIGS. 4D and 4E ), the target inter-vehicle distance calculation unit 303 may set one of the multiple values ​​to a value within a specific range and calculate the corresponding inter-vehicle distance as the target inter-vehicle distance. This reduces the processing time required to identify the minimum value by sequentially comparing the magnitudes of the actual torque in chronological order, and makes it possible to set an inter-vehicle distance that will result in a value close to the minimum for the running energy consumption of the following vehicle.

[0067] (Specific Example 3 of Calculating Target Inter-Vehicle Distance) When there are multiple values ​​at which the actual torque changes from decreasing to increasing, the target inter-vehicle distance calculation unit 303 may set the lowest value (see FIG. 4D ) among the multiple values ​​as a value within a specific range and calculate the corresponding inter-vehicle distance as the target inter-vehicle distance. This makes it possible to set an inter-vehicle distance that minimizes the driving energy consumption of the following vehicle.

[0068] (Specific Example 4 of Calculating Target Inter-Vehicle Distance) When there are multiple values ​​when the actual torque changes from decreasing to increasing and the multiple values ​​are equal (see FIG. 4E ), the target inter-vehicle distance calculation unit 303 may set the value of the multiple values ​​that corresponds to the position where the following vehicle is farthest from the leading vehicle as a value within a specific range, and calculate the corresponding inter-vehicle distance as the target inter-vehicle distance. This makes it possible to set an inter-vehicle distance that minimizes the driving energy consumption of the following vehicle while maintaining a safe inter-vehicle distance.

[0069] (Specific Example 5 of Calculating Target Inter-Vehicle Distance) The target inter-vehicle distance calculation unit 303 may compare, among the actual torques, the actual torque at a first time point with the actual torque at a second time point that is earlier than the first time point, and may determine, as a result of the comparison, that the smaller actual torque is within a specific range, and calculate the corresponding inter-vehicle distance as the target inter-vehicle distance. Specifically, the target inter-vehicle distance calculation unit 303 may, for example, compare, among the actual torques detected in chronological order, the most recent actual torque detected this time with the smallest value among the actual torques detected up to the last time. The comparison may be continued, for example, until the following vehicle reaches a safe inter-vehicle distance (specific inter-vehicle distance), or until the following vehicle reaches (or becomes equal to) the specific distance described above.

[0070] The safe following distance may be interpreted as a distance that increases the possibility of avoiding a collision of a following vehicle with a leading vehicle. Specifically, the safe following distance may be interpreted as the braking distance that can avoid a collision of a following vehicle with a leading vehicle, a cutting-in vehicle, etc., or the braking distance plus the free-running distance. The free-running distance may be interpreted as the distance traveled from the time the driver senses danger and applies the brakes until the brakes actually start to operate. The braking distance may be interpreted as the distance traveled from the time the brakes are applied until the following vehicle stops.

[0071] If the comparison shows that the currently detected actual torque is smaller than the minimum value among the actual torques detected up to the last time, the target inter-vehicle distance calculation unit 303 may calculate the corresponding inter-vehicle distance corresponding to the currently detected actual torque as the target inter-vehicle distance. In other words, the target inter-vehicle distance may be updated. On the other hand, if the currently detected actual torque is greater than the minimum value among the previously detected actual torques, the target inter-vehicle distance may be calculated as the corresponding inter-vehicle distance corresponding to the minimum value among the previously detected actual torques.

[0072] By comparing the magnitude of the actual torque in chronological order in this way, it is possible to easily set an inter-vehicle distance that will result in a value close to the minimum for the running energy consumption of the following vehicle.

[0073] (Specific Example 6 of Calculating Target Inter-Vehicle Distance) The target inter-vehicle distance calculation unit 303 may calculate, as the target inter-vehicle distance, a corresponding inter-vehicle distance that corresponds to the smallest value (minimum value) of the actual torque within a specific range. This makes it possible to maintain an inter-vehicle distance that minimizes the consumption of driving energy by the following vehicle.

[0074] (Specific Example 7 of Calculating Target Inter-Vehicle Distance) When the specific inter-vehicle distance is a safe inter-vehicle distance and the applicable inter-vehicle distance is shorter than the safe inter-vehicle distance, the target inter-vehicle distance calculation unit 303 may calculate the safe inter-vehicle distance instead of the applicable inter-vehicle distance as the target inter-vehicle distance. On the other hand, when the applicable inter-vehicle distance is longer than the safe inter-vehicle distance, the target inter-vehicle distance calculation unit 303 may calculate the applicable inter-vehicle distance instead of the safe inter-vehicle distance as the target inter-vehicle distance.

[0075] This makes it possible to reduce the running energy consumption of the following vehicle while maintaining a safe distance when the following distance is shorter than the safe following distance, and also makes it possible to reduce the running energy consumption of the following vehicle while maintaining a safer distance when the following distance is longer than the safe following distance.

[0076] (Specific Example 8 of Calculating Target Inter-Vehicle Distance) The target inter-vehicle distance calculation unit 303 may calculate the corresponding inter-vehicle distance as the target inter-vehicle distance while a specific function is being executed. The specific function may include cruise control (CC), a platooning mode, an autonomous driving mode, an autonomous lane keeping mode, etc. For example, if the following vehicle is not executing a specific function, the target inter-vehicle distance calculation unit 303 may not need to calculate the corresponding inter-vehicle distance as the target inter-vehicle distance, and may calculate the corresponding inter-vehicle distance as the target inter-vehicle distance only when the following vehicle is executing a specific function.

[0077] In this way, by calculating the corresponding inter-vehicle distance as the target inter-vehicle distance only while a specific function is being executed, it is possible to prevent the driver from feeling uncomfortable with accelerator operation when the specific function is not being executed, for example, because the vehicle is being driven manually. Also, at the driver's discretion, the vehicle can be shifted to a low air resistance driving mode that reduces the driving energy consumption of the following vehicle.

[0078] (Another example configuration 1 of the target inter-vehicle distance calculation unit 303) After resetting the reference target torque estimated by the reference target torque estimation unit 302 up to that point, the target inter-vehicle distance calculation unit 303 may estimate an initial value of the inter-vehicle distance when estimation of the reference target torque starts based on the projected area of ​​the preceding vehicle, and calculate the corresponding inter-vehicle distance when the inter-vehicle distance is changed as the target inter-vehicle distance based on the estimated initial value.

[0079] For example, when a specific vehicle cuts in between the leading vehicle and the following vehicle and the reference target torque estimated up until the cut-in detection is reset, the target inter-vehicle distance calculation unit 303 then calculates the projection area of ​​the specific vehicle that cut in (cut-in vehicle). The calculation of the projection area may be performed, for example, by taking the vertical width of a group of pixels constituting an image on a transparent surface of the back of the cutting in vehicle as viewed from the following vehicle in a plan view in an image captured by the imaging device 205 provided on the following vehicle as the vehicle height of the leading vehicle, and taking the horizontal width of the group of pixels as the vehicle width of the leading vehicle, and calculating the value of the product of the vehicle height and the vehicle width as the projection area of ​​the leading vehicle.

[0080] The target inter-vehicle distance calculation unit 303, which has calculated the projected area as described above, may estimate the initial inter-vehicle distance using, for example, a target inter-vehicle distance initial value map (hereinafter referred to as the initial value map) shown in FIG. 6 . The vertical axis in FIG. 6 represents the initial inter-vehicle distance, and the horizontal axis in FIG. 6 represents the vehicle speed. The solid line represents the initial inter-vehicle distance value versus vehicle speed when the preceding vehicle is a large vehicle (e.g., a bus, truck, or passenger car). The dashed line represents the initial inter-vehicle distance value versus vehicle speed when the preceding vehicle is a small vehicle (e.g., a compact car with a total engine displacement of 2,000 cc or less, and dimensions of 4.7 m or less in length, 1.7 m or less in width, and 2.0 m or less in height). Since the projected area of ​​a large vehicle is smaller than that of a small vehicle, the initial inter-vehicle distance value for a large vehicle tends to be larger than the initial inter-vehicle distance value for a small vehicle. In other words, as indicated by the dashed arrow, the larger the projected area of ​​the preceding vehicle (the preceding vehicle), the larger the initial inter-vehicle distance value. These initial values ​​also tend to increase as the vehicle speed increases.

[0081] (Another example configuration 2 of the target inter-vehicle distance calculation unit 303) The target inter-vehicle distance calculation unit 303 may refer to a map that associates multiple inter-vehicle distances between a leading vehicle and a following vehicle with multiple different speed ranges of the following vehicle, and calculate the inter-vehicle distance that corresponds to a speed range among the multiple speed ranges that includes the speed of the following vehicle following the leading vehicle as the target inter-vehicle distance.

[0082] For example, the target inter-vehicle distance, which is the optimal inter-vehicle distance for low air resistance, should ideally be calculated at a constant vehicle speed (for example, a constant 92 kph). However, in actual driving situations, the speed of the preceding vehicle changes, so it is necessary to calculate the optimal inter-vehicle distance in accordance with the change in the speed of the preceding vehicle.

[0083] As a countermeasure, the target inter-vehicle distance calculation unit 303 may refer to a map (KYORIMAP) shown in Fig. 7, which associates vehicle speeds with optimal inter-vehicle distances. The vertical axis of Fig. 7 represents the optimal inter-vehicle distance from the leading vehicle to the following vehicle, and the horizontal axis of Fig. 7 represents the vehicle speed of the following vehicle.

[0084] KYORIMAP has, for example, three speed ranges (low speed range L, medium speed range M, high speed range H) and optimum inter-vehicle distances (L_LOW, L_MID, L_HIG) set within each speed range. The low speed range L is, for example, 90 to 97 KPH, the medium speed range M is, for example, 97 to 103 KPH, and the high speed range H is, for example, 103 to 110 KPH. The optimum inter-vehicle distance L_LOW in the low speed range L may be shorter than the optimum inter-vehicle distance L_MID in the medium speed range M, and the optimum inter-vehicle distance L_MID in the medium speed range M may be shorter than the optimum inter-vehicle distance L_HIG in the high speed range H.

[0085] For example, when the target inter-vehicle distance calculation unit 303 receives the reference target torque estimated by the reference target torque estimation unit 302 when a specific condition is satisfied, if the current vehicle speed Vb is 95 KPH, the target inter-vehicle distance calculation unit 303 may calculate the optimal inter-vehicle distance L_LOW corresponding to the low speed range L, which includes this speed, as the target inter-vehicle distance.

[0086] Similarly, when the target inter-vehicle distance calculation unit 303 receives the reference target torque, if the current vehicle speed Vb is 100 KPH, it may calculate the optimal inter-vehicle distance L_MID corresponding to the medium speed range M, which includes this speed, as the target inter-vehicle distance.

[0087] Furthermore, when the target inter-vehicle distance calculation unit 303 receives the reference target torque, if the current vehicle speed Vb is 105 KPH, it may calculate the optimal inter-vehicle distance L_HIG corresponding to the high speed range H, which includes this speed, as the target inter-vehicle distance.

[0088] As a result, even if the speed of the following vehicle changes due to a change in the speed of the preceding vehicle, the target inter-vehicle distance corresponding to a specific speed range including the changed vehicle speed, that is, the inter-vehicle distance at which the following vehicle can travel with the minimum torque, can be instantly calculated.

[0089] (Inter-vehicle distance transmitting unit 304) The inter-vehicle distance transmitting unit 304 may transmit the target inter-vehicle distance to the ACC system 106 via CAN communication. For example, when the inter-vehicle distance transmitting unit 304 receives an instruction 400a to execute search control transmitted by the driver operating the switch 400, the inter-vehicle distance transmitting unit 304 may transmit the target inter-vehicle distance to the ACC system 106 via CAN communication at the timing of receiving the instruction 400a to execute search control. This allows the ACC system 106 to instantly calculate the ACC target torque TACC for maintaining the target inter-vehicle distance. Therefore, even when the inter-vehicle distance between the leading vehicle and the following vehicle is relatively close, it is possible to set an inter-vehicle distance that maintains a safe inter-vehicle distance while minimizing the driving energy consumption of the following vehicle.

[0090] (Execution Flag Transmission Unit 305) When the execution flag transmission unit 305 receives the instruction 400a to execute the search control, it may transmit a low air resistance search control execution flag XLOWRES, which is a flag that permits the execution of the low air resistance search control, to the ACC system 106. For convenience of explanation, the low air resistance search control execution flag XLOWRES may be referred to below simply as the "execution flag XLOWRES".

[0091] (Target Torque Selection Unit 306) The target torque selection unit 306 may select either the accelerator target torque TACL or the ACC target torque TACC, and input the selected torque as the target torque (MG target torque TMG) ​​of the rotating electric machine 103 for driving the following vehicle to the inverter 102. The ACC target torque TACC may be calculated by the ACC system 106 that receives the target inter-vehicle distance from the target inter-vehicle distance calculation unit 303.

[0092] For example, when receiving the accelerator target torque TACL and the ACC target torque TACC, the target torque selection unit 306 may select the larger one. Specifically, when the ACC target torque TACC is larger than the accelerator target torque TACL, the target torque selection unit 306 may select the ACC target torque TACC, and when the ACC target torque TACC is smaller than the accelerator target torque TACL, the target torque selection unit 306 may select the accelerator target torque TACL. The target torque selection unit 306 may input the selected ACC target torque TACC to the inverter 102 as the MG target torque TMG. The inverter 102 executes torque control commensurate with the MG target torque TMG, which is the command torque value.

[0093] (Functional Allocation of Searching Control and Inter-Vehicle Distance Control) The vehicle control device 300 and the ACC system 106 may share the functions of searching control and inter-vehicle distance control. By sharing the functions of searching control and inter-vehicle distance control, it is possible to achieve highly accurate functionality while minimizing modifications to the ACC system 106. In other words, it is possible to accurately estimate the inter-vehicle distance at which the torque of the following vehicle becomes low while traveling.

[0094] For example, when the ACC input switch 500 is operated while the instruction 400a to execute searching control has not been input to the vehicle control device 300, a signal (ACC input 500a) to start the execution of normal adaptive cruise control is input to the ACC system 106. In this case, the ACC system 106 may execute the preceding vehicle following control, constant vehicle speed control, etc., as described above. At this time, the vehicle control device 300 may not execute the above-described (1_a) execution determination of low air resistance searching control, (1_b) estimation of the reference target torque, and (1_c) calculation of the target inter-vehicle distance.

[0095] When the instruction 400a to execute the searching control is input to the vehicle control device 300, the vehicle control device 300 may execute the above-mentioned (1_a) execution determination of the low air resistance searching control, (1_b) estimation of the reference target torque, and (1_c) calculation of the target inter-vehicle distance. When the target inter-vehicle distance and the execution flag XLOWRES are input from the vehicle control device 300, the ACC system 106 may generate an ACC target torque TACC, which is an MG torque for maintaining the target inter-vehicle distance constant, and transmit this ACC target torque TACC to the inverter 102 via the vehicle control device 300.

[0096] The functions of search control and inter-vehicle distance control may be provided in the vehicle control device 300.

[0097] When the ACC system 106 detects a cutting-in vehicle, it may input a cutting-in detection flag XWARIKOMI via CAN communication to the vehicle control device 300. For example, when a vehicle cuts in between a leading vehicle and a following vehicle, causing the inter-vehicle distance measured by the external sensor 203 to change in a short period of time, the ACC system 106 may determine that a cutting-in has occurred and may generate the cutting-in detection flag XWARIKOMI.

[0098] When receiving the ACC input 500a, the ACC system 106 may execute cruise control, that is, the aforementioned adaptive cruise control, constant vehicle speed control, etc. The ACC system 106 executing cruise control may input an ACC execution flag XACC, which indicates that cruise control is being executed, to the vehicle control device 300 via CAN communication.

[0099] Next, the operation of the vehicle control device 300 will be described with reference to Fig. 8 to Fig. 15. Fig. 8 is a flowchart showing an example of an operation for determining whether or not to execute low air resistance search control. Fig. 9 is a flowchart showing an example of an operation for estimating MG torque when a reference condition is satisfied. Fig. 10 is a flowchart showing an example of an operation for low air resistance search control in step S24 of Fig. 9.

[0100] 8, if the vehicle control device 300 receives the ACC execution flag XACC from the ACC system 106 via CAN communication, it may execute the process of step S2 (see time t1 in FIG. 11). If the vehicle control device 300 has not received the ACC execution flag XACC, it may execute the process of step S12.

[0101] In step S2, the vehicle control device 300 may compare the ACC target torque TACC with the accelerator target torque TACL. If the ACC target torque TACC is greater than the accelerator target torque TACL, the vehicle control device 300 may execute the process of step S3, and if the ACC target torque TACC is smaller than the accelerator target torque TACL, the vehicle control device 300 may execute the process of step S12.

[0102] In step S3, if the vehicle control device 300 receives an instruction 400a to perform search control, it may execute the processing of step S4, and if the vehicle control device 300 does not receive an instruction 400a to perform search control, it may execute the processing of step S12.

[0103] In step S4, if the vehicle speed Vb is within a specific speed range, the vehicle control device 300 may execute the process of step S5, and if the vehicle speed Vb is outside the specific speed range, the vehicle control device 300 may execute the process of step S12.

[0104] In step S5, if the acceleration / deceleration ΔVb is within the specific acceleration / deceleration range, the vehicle control device 300 may execute the process of step S6, and if the acceleration / deceleration ΔVb is outside the specific acceleration / deceleration range, the vehicle control device 300 may execute the process of step S12.

[0105] In step S6, if the gradient θr is within a specific gradient range, the vehicle control device 300 may execute the process of step S7, and if the acceleration / deceleration ΔVb is outside the specific gradient range, the vehicle control device 300 may execute the process of step S12.

[0106] In step S7, if the steering angle θEPS is within a specific steering angle range, the vehicle control device 300 may execute the processing of step S8, and if the steering angle θEPS is outside the specific steering angle range, the vehicle control device 300 may execute the processing of step S12.

[0107] In step S8, if the lateral deviation amount ΔZURE is within a specific range (see Figure 13A), the vehicle control device 300 may execute the processing of step S9, and if the lateral deviation amount ΔZURE is outside the specific range (see Figure 13B), the vehicle control device 300 may execute the processing of step S12.

[0108] In step S9, if the speed difference is within a specific range, the vehicle control device 300 may execute the process of step S10, and if the speed difference is outside the specific range, the vehicle control device 300 may execute the process of step S12.

[0109] If the vehicle control device 300 has not received the interruption detection flag XWARIKOMI in step S10, the vehicle control device 300 may execute the process of step S11. On the other hand, if the vehicle control device 300 has received the interruption detection flag XWARIKOMI in step S10, the vehicle control device 300 may execute the process of step S12. For example, time t17 in Figure 12 may be interpreted as the timing when the interruption detection flag XWARIKOMI is received.

[0110] In step S11, the vehicle control device 300 may set the execution flag XLOWRES to 1 to permit the execution of low air resistance search control for a following vehicle that is traveling steadily on a highway (see time t2 in FIG. 11 ). Steady traveling may be interpreted as a state in which the vehicle speed is approximately constant, there is little change in speed, the vehicle is traveling on a road that can be considered straight, the road surface on which the vehicle is traveling is flat, the center position of the following vehicle in the lateral direction approximately coincides with the center position of the preceding vehicle in the lateral direction, etc.

[0111] In step S12, the vehicle control device 300 may not set the execution flag XLOWRES to 1, but may leave it at 0, in order to prohibit the execution of low air resistance search control.

[0112] In the present disclosure, the process of step S11 is executed when all the conditions of steps S3 to S9 are satisfied, but the process of step S11 may be executed when at least one of the conditions of steps S3 to S9 is satisfied. However, when all of these conditions are satisfied, the accuracy of the inter-vehicle distance at which the driving energy consumption of the following vehicle is minimized or close to the minimum value can be improved.

[0113] 9, the vehicle control device 300 determines whether the execution flag XLOWRES is set to 1. If the execution flag XLOWRES is set to 1, the vehicle control device 300 may execute the process of step S14. If the execution flag XLOWRES is set to 0, the vehicle control device 300 may execute the process of step S16.

[0114] In step S16, the vehicle control device 300 may set the low air resistance search counter CLOWRES to 0 because the traveling state of the following vehicle does not satisfy the specific condition.

[0115] In step S17, the search execution flag XEX_ ＊ is set to 0, and the search end flag XEND_ ＊ is set to 1. For example, when the MAP shown in FIG. 7 is being created, the search in progress flag XEX_ is set to 1. ＊ is set to 1 and the creation of the MAP is suspended, the search in progress flag XEX_ ＊ During the low air resistance search, the search end flag XEND is set to 0, and when the low air resistance search is completed, the search end flag XEND_ ＊ These flags are set to 1. These flags are set to correspond to any of the low speed range L, medium speed range M, and high speed range H described above.

[0116] In step S18, the maximum value that a RAM (Random Access Memory) value can take is set as the target inter-vehicle distance, and at this time, the ACC system 106 may control the inter-vehicle distance using normal cruise control. For example, as shown at times t17 to t18 in FIG. 12, the RAM value may be set to, for example, 80 m.

[0117] In step S19 , the vehicle control device 300 may transmit the target inter-vehicle distance to the ACC system 106 .

[0118] In step S14, the vehicle control device 300 may calculate the MG torque difference correction amount, for example, using the above-mentioned equations (20) to (24), and in step S15, the vehicle control device 300 may calculate the reference target torque, for example, using the above-mentioned equation (25) (see, for example, times t3 to t5 in Figure 11).

[0119] In step S20, the vehicle control device 300 may start counting up the low air resistance search counter CLOWRES because the driving state of the following vehicle satisfies a specific condition. The reason for counting up is to ensure time required for processes such as changing the inter-vehicle distance and calculating the projected area from the image data until a specific calculation period (e.g., 2 seconds) has elapsed since the specific condition was satisfied. This calculation period can be interpreted as the time required for the target inter-vehicle distance calculation unit 303 to calculate the target inter-vehicle distance, and is longer, i.e., has a lower calculation frequency, than the calculation period (e.g., 10 ms, 20 ms, etc.) used by the reference target torque estimation unit 302 to estimate the reference target torque. By providing a difference of about one digit in the calculation period, interference between the process of estimating the reference target torque and processes such as adjusting the inter-vehicle distance when calculating the target inter-vehicle distance can be suppressed.

[0120] In step S21, if the low air resistance search counter CLOWRES is less than 2 seconds, for example, the vehicle control device 300 may execute the process of step S17.

[0121] In step S21, if the low air resistance search counter CLOWRES reaches, for example, 2 seconds, the vehicle control device 300 may execute the process of step S22.

[0122] In step S21, if the low air resistance search counter CLOWRES exceeds, for example, 2 seconds, the vehicle control device 300 may execute the process of step S23.

[0123] In step S22, the vehicle control device 300 may refer to the initial value MAP shown in Figure 6 to set the target inter-vehicle distance to the initial value of the inter-vehicle distance when starting (resuming) the search control, and then execute the processing of step S19 (see time t5 in Figure 11).

[0124] In step S23, if the remainder obtained by dividing the value of the low air resistance search counter CLOWRES by, for example, 2s, is 0, the vehicle control device 300 may execute the process of step S24.

[0125] The vehicle control device 300 may execute the process of step S19 when the remainder obtained by dividing the value of the low air resistance search counter CLOWRES by, for example, 2s is other than 0.

[0126] In step S24, the vehicle control device 300 may execute low air resistance search control, and then execute the processing of step S25 (see times t5 to t8 in FIG. 11).

[0127] In step S25, the vehicle control device 300 may refer to the above-mentioned KYORIMAP and set the optimal inter-vehicle distance corresponding to each speed range as the target inter-vehicle distance, and then execute the process of step S19. The target inter-vehicle distance set at this time may be interpreted as the corresponding inter-vehicle distance searched for, for example, from time t7 to time t8 in FIG. 11 during the search for low air resistance.

[0128] In step S31 shown in FIG. 10, the vehicle control device 300 sets the search execution flag XEX_ ＊ If the search execution flag XEX_ has changed from 0 to 1, the vehicle control device 300 may execute the process of step S32. ＊ If it has not changed from 0 to 1, the process of step S33 may be executed.

[0129] In step S32, the vehicle control device 300 may set the current vehicle speed Vb as the stored value Vbo of the vehicle speed when starting the search for low air resistance.

[0130] In step S33, if the absolute value of the difference between the current vehicle speed Vb and the stored value Vbo is less than 3 kph, for example, that is, if the change in vehicle speed after the start of the low air resistance search is small, the vehicle control device 300 may execute the process of step S34. If the absolute value of the difference between the current vehicle speed Vb and the stored value Vbo is greater than or equal to 3 kph, that is, if the change in vehicle speed after the start of the low air resistance search is large, the vehicle control device 300 may execute the process of step S42 to restart the low air resistance search.

[0131] In step S34, the vehicle control device 300 sets the search end flag XEND_ ＊ If the search end flag XEND_ is 0, the vehicle control device 300 may execute the process of step S35. ＊ If the value is 1, the search for low air resistance has been completed, and the process of step S42 may be executed.

[0132] In step S35, if the current vehicle speed Vb is within a specific vehicle speed range, the vehicle control device 300 may execute the process of step S36. If the current vehicle speed Vb is outside the specific vehicle speed range, the vehicle control device 300 may execute the process of step S42 to redo the low air resistance search. Specifically, when performing a low air resistance search in the low speed range L (e.g., 90 kph to 97 kph) shown in FIG. 7 , the vehicle control device 300 may execute the process of step S36 if the driver operates the accelerator pedal with a constant force and the vehicle speed Vb is within the low speed range L. On the other hand, if the vehicle speed Vb exceeds the low speed range L because the driver depresses the accelerator pedal more strongly, the vehicle control device 300 cannot appropriately search for the target inter-vehicle distance at which torque is minimized in the low speed range L. Therefore, the vehicle control device 300 may execute the process of step S42 to redo the low air resistance search.

[0133] In step S36, the vehicle control device 300 sets the search execution flag XEX_ ＊ While maintaining the value "1", the process of step S37 may be executed.

[0134] In step S37, if the reference target torque is smaller than the minimum value TMGMIN of the actual torques being searched, the vehicle control device 300 may execute the process of step S38 to record the vehicle speed Vb at that time, the MG torque (reference target torque: TMGMIN) generated at that vehicle speed Vb, and the target inter-vehicle distance at that time in the MAP. On the other hand, if the reference target torque is equal to or greater than the minimum value TMGMIN of the actual torques being searched, the MG torque tends to be larger by TMGMIN. In this case, the vehicle control device 300 may execute the process of step S40 to end the low air resistance search.

[0135] In step S38, the vehicle control device 300 may set the minimum value TMGMIN being searched for as the reference target torque. The vehicle control device 300 may also set the vehicle speed Vb and the target inter-vehicle distance when this reference target torque is being generated, in correspondence with the vehicle speed and target inter-vehicle distance on the KYORIMAP.

[0136] In step S39, the vehicle control device 300 may set the target inter-vehicle distance to a value obtained by adding 1 meter to the previously calculated target inter-vehicle distance by moving the following vehicle away from the leading vehicle, for example, by 1 meter every 2 seconds. Note that the vehicle control device 300 may set the target inter-vehicle distance to a value obtained by adding 1 meter to the previously calculated target inter-vehicle distance by moving the following vehicle closer to the leading vehicle, for example, by 1 meter every 2 seconds.

[0137] In step S40, the vehicle control device 300 ends the search for low air resistance by setting the search end flag XEND_ ＊ In step S41, the vehicle control device 300 sets the search execution flag XEX_ ＊ Set to 0.

[0138] In step S42, the vehicle control device 300 resets the search in progress flag XEX_ ＊ Set to 0.

[0139] For example, when searching control is started at time t2 in FIG. 11, an initial value at the start of searching control is set at time t5 in FIG. 11 (see also FIG. 14). Thereafter, for example, by gradually bringing the following vehicle closer to the preceding vehicle, the corresponding inter-vehicle distance is searched for as the inter-vehicle distance is gradually reduced. Specifically, from time t6 to time t8 in FIG. 11, TMGMIN decreases. Then, since TMGMIN after time t8 is greater than TMGMIN from time t7 to time t8, the inter-vehicle distance corresponding to TMGMIN from time t7 to time t8 may be set as the corresponding inter-vehicle distance (see also FIG. 14).

[0140] (Action, effect) As described above, the vehicle control device 300 of the present disclosure may estimate a reference target torque for driving a following vehicle following a leading vehicle when the driving state of the following vehicle satisfies specific conditions, and may calculate, as the target inter-vehicle distance, a corresponding inter-vehicle distance that corresponds to the minimum torque generated based on the reference target torque when the inter-vehicle distance is changed based on the estimated reference target torque.

[0141] This allows the system to properly calculate the target inter-vehicle distance that minimizes the air resistance of the following vehicle while eliminating external disturbances. Therefore, by maintaining the target inter-vehicle distance, the following vehicle's consumption of driving energy can be reduced.

[0142] It should be noted that the vehicle 100 of the present disclosure is not limited to an electric vehicle. For example, the vehicle 100 may be a hybrid vehicle equipped with an internal combustion engine in addition to the rotating electric machine 103, or may be a conventional engine vehicle equipped with only an internal combustion engine instead of the rotating electric machine 103.

[0143] The controller and methods described herein may be implemented by a special-purpose computer having a processor programmed to perform one or more functions embodied in a computer program. Alternatively, the apparatus and methods described herein may be implemented by a special-purpose computer having a processor configured with dedicated hardware logic circuitry. Alternatively, the apparatus and methods described herein may be implemented by one or more special-purpose computers configured by a combination of a processor executing a computer program and one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory storage medium.

[0144] <Additional Notes> The features of the present invention are as follows.

[0145] (Supplementary Note 1) A vehicle control device (300) comprising: a reference target torque estimation unit (302) that estimates, based on vehicle information, a reference target torque for causing a following vehicle (100) following a preceding vehicle to travel when the traveling state of the following vehicle satisfies a specific condition; and a target inter-vehicle distance calculation unit (303) that, based on the reference target torque, calculates, as a target inter-vehicle distance, a corresponding inter-vehicle distance that corresponds to a value within a specific range including a minimum value of the actual torque generated based on the reference target torque when the inter-vehicle distance from the preceding vehicle to the following vehicle is changed.

[0146] (Supplementary Note 2) When the driving state satisfies the specific condition, the vehicle control device according to Supplementary Note 1 includes at least one of the following: the vehicle speed of the following vehicle while traveling on a highway is within a specific speed range; the gradient of the road surface of the highway is within a specific gradient range; the steering angle of the following vehicle while traveling on a highway is within a specific steering angle range; the acceleration / deceleration of the following vehicle while traveling on a highway is within a specific acceleration / deceleration range; the amount of lateral deviation of the following vehicle in the width direction relative to the preceding vehicle is within a specific range; and the speed difference between the preceding vehicle and the following vehicle is within a specific range.

[0147] (Supplementary Note 3) The vehicle control device according to Supplementary Note 1 or 2, wherein the reference target torque estimation unit does not estimate the reference target torque when the specific condition is not satisfied, and estimates the reference target torque when the specific condition is satisfied.

[0148] (Supplementary Note 4) The vehicle control device described in any one of Supplementary Notes 1 to 3, wherein when the reference target torque estimation unit detects that a specific vehicle has cut in between the leading vehicle and the following vehicle during a period in which the following vehicle is performing driving control to follow the leading vehicle while maintaining the corresponding inter-vehicle distance, the reference target torque estimation unit resets the reference target torque estimated up to the detection, and then regards the specific vehicle as the leading vehicle, and re-estimates the reference target torque for the following vehicle to travel when the driving state of the following vehicle following the leading vehicle satisfies the specific condition; and the target inter-vehicle distance calculation unit, after the reset, estimates an initial value of the inter-vehicle distance when estimation of the reference target torque is started based on a projected area of ​​the leading vehicle calculated using an image captured by an imaging device provided on the following vehicle, and calculates the corresponding inter-vehicle distance when the inter-vehicle distance is changed based on the estimated initial value.

[0149] (Supplementary Note 5) A vehicle control device according to any one of Supplementary Notes 1 to 4, wherein an adaptive cruise function (106) including at least one of a constant speed control that controls the speed of the following vehicle so that the speed of the following vehicle is equal to or less than a set speed, and a leading vehicle following control that controls the speed and the distance between the preceding vehicle and the following vehicle so that the distance between the preceding vehicle and the following vehicle becomes a set distance, comprises: an inter-vehicle distance transmitting unit (304) that transmits the target inter-vehicle distance via CAN (Controller Area Network: registered trademark) communication; and a target torque selecting unit (306) that selects a torque for maintaining the target inter-vehicle distance constant, calculated by the adaptive cruise function that has received the target inter-vehicle distance, and inputs the selected torque to an inverter as a target torque of a rotating electric machine for driving the following vehicle.

[0150] (Appendix 6) The vehicle control device described in Appendix 5, wherein the inter-vehicle distance transmission unit transmits the target inter-vehicle distance to the adaptive cruise function via the CAN communication when receiving an instruction (400a) to execute driving control to cause the following vehicle to follow the leading vehicle with low air resistance.

[0151] (Appendix 7) A vehicle control device described in any one of Appendices 1 to 6, wherein a calculation period for estimating the reference target torque when the reference target torque estimation unit satisfies the specific condition is shorter than a calculation period for calculating the corresponding inter-vehicle distance as the target inter-vehicle distance by the target inter-vehicle distance calculation unit.

[0152] (Appendix 8) A vehicle control device as described in any one of Appendices 1 to 7, wherein the target inter-vehicle distance calculation unit refers to a map (KYORIMAP) that associates multiple inter-vehicle distances between the leading vehicle and the following vehicle with multiple different speed ranges of the following vehicle, and estimates, as the reference target torque, an inter-vehicle distance that corresponds to a speed range that includes the speed of the following vehicle following the leading vehicle, among the multiple speed ranges.

[0153] (Supplementary Note 9) A vehicle control program (2a) that causes at least one processor (3) to execute processing including: estimating, based on vehicle information, a reference target torque for causing a following vehicle following a leading vehicle to travel when the traveling state of the following vehicle satisfies a specific condition; and calculating, based on the reference target torque, a corresponding inter-vehicle distance that corresponds to a value within a specific range including the minimum value of the actual torque generated based on the reference target torque when the inter-vehicle distance from the leading vehicle to the following vehicle is changed.

[0154] (Supplementary Note 10) A vehicle control method in which at least one processor executes processing including: estimating, based on vehicle information, a reference target torque for causing a following vehicle following a leading vehicle to travel when the traveling state of the following vehicle satisfies a specific condition; and calculating, based on the reference target torque, a corresponding inter-vehicle distance that corresponds to a value within a specific range including the minimum value of the actual torque generated based on the reference target torque when the inter-vehicle distance from the leading vehicle to the following vehicle is changed.

[0155] The above describes one embodiment of the present invention, but the present invention is not limited to the above, and it goes without saying that the present invention can be implemented in various modified forms within the scope of the gist of the present invention.

Claims

1. A vehicle control device (300) comprising: a reference target torque estimation unit (302) that estimates, based on vehicle information, a reference target torque for causing a following vehicle (100) following a preceding vehicle to travel when the traveling state of the following vehicle satisfies a specific condition; and a target inter-vehicle distance calculation unit (303) that, based on the reference target torque, calculates, as a target inter-vehicle distance, a corresponding inter-vehicle distance that corresponds to a value within a specific range including the minimum value of an actual torque generated based on the reference target torque when the inter-vehicle distance from the preceding vehicle to the following vehicle is changed.

2. A vehicle control device as described in claim 1, wherein when the driving state satisfies the specific condition, the vehicle speed of the following vehicle while traveling on a highway is within a specific speed range, the gradient of the road surface of the highway is within a specific gradient range, the steering angle of the following vehicle while traveling on a highway is within a specific steering angle range, the acceleration / deceleration of the following vehicle while traveling on a highway is within a specific acceleration / deceleration range, the relative lateral deviation of the following vehicle in the width direction with respect to the preceding vehicle is within a specific range, and the speed difference between the preceding vehicle and the following vehicle is within a specific range.

3. The vehicle control device according to claim 1, wherein the reference target torque estimation unit does not estimate the reference target torque when the specific condition is not satisfied, and estimates the reference target torque when the specific condition is satisfied.

4. The vehicle control device described in claim 1, wherein, when the reference target torque estimation unit detects that a specific vehicle has cut in between the leading vehicle and the following vehicle while the following vehicle is performing driving control to follow the leading vehicle while maintaining the corresponding inter-vehicle distance, the reference target torque estimation unit resets the reference target torque estimated up to the detection, regards the specific vehicle as the leading vehicle, and re-estimates the reference target torque for the following vehicle to travel when the driving state of the following vehicle following the leading vehicle satisfies the specific condition; and the target inter-vehicle distance calculation unit, after the reset, estimates an initial value of the inter-vehicle distance when estimation of the reference target torque is started based on a projected area of ​​the leading vehicle calculated using an image captured by an imaging device provided on the following vehicle, and calculates the corresponding inter-vehicle distance when the inter-vehicle distance is changed based on the estimated initial value as the target inter-vehicle distance.

5. A vehicle control device as described in claim 1, wherein the adaptive cruise function (106) includes at least one of a constant speed control that controls the speed of the following vehicle so that it is equal to or lower than a set speed, and a leading vehicle following control that controls the speed and distance between the preceding vehicle and the following vehicle so that the distance between the preceding vehicle and the following vehicle becomes a set distance, and further comprises: an inter-vehicle distance transmitting unit (304) that transmits the target inter-vehicle distance via CAN (Controller Area Network: registered trademark) communication; and a target torque selecting unit (306) that selects a torque for maintaining the target inter-vehicle distance constant, calculated by the adaptive cruise function that has received the target inter-vehicle distance, and inputs the selected torque to an inverter as a target torque for a rotating electric machine for driving the following vehicle.

6. A vehicle control device as described in claim 5, wherein the inter-vehicle distance transmission unit transmits the target inter-vehicle distance to the adaptive cruise function via the CAN communication when it receives an instruction (400a) to execute driving control to cause the following vehicle to follow the leading vehicle with low air resistance.

7. A vehicle control device as described in claim 1, wherein the calculation period in which the reference target torque estimation unit estimates the reference target torque when the specific condition is satisfied is shorter than the calculation period in which the target inter-vehicle distance calculation unit calculates the corresponding inter-vehicle distance as the target inter-vehicle distance.

8. The vehicle control device described in claim 1, wherein the target inter-vehicle distance calculation unit refers to a map (KYORIMAP) that associates multiple inter-vehicle distances between the leading vehicle and the following vehicle with multiple different speed ranges of the following vehicle, and estimates the inter-vehicle distance corresponding to a speed range that includes the speed of the following vehicle following the leading vehicle, among the multiple speed ranges, as the reference target torque.

9. A vehicle control program (2a) that causes at least one processor (3) to execute processing including: estimating, based on vehicle information, a reference target torque for causing a following vehicle following a leading vehicle to travel when the traveling state of the following vehicle satisfies a specific condition; and calculating, as a target following distance, a corresponding following distance that corresponds to a value within a specific range including the minimum value of the actual torque generated based on the reference target torque when the following distance from the leading vehicle to the following vehicle is changed based on the reference target torque.

10. A vehicle control method in which at least one processor executes processing including: estimating, based on vehicle information, a reference target torque for driving a following vehicle following a leading vehicle when the driving state of the following vehicle satisfies a specific condition; and calculating, as a target following distance, a corresponding following distance that corresponds to a value within a specific range including the minimum value of the actual torque generated based on the reference target torque when the following distance from the leading vehicle to the following vehicle is changed based on the reference target torque.

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