Driving assistance device, recording medium, and driving assistance method

Abstract

The present invention provides a driving assistance device, a recording medium, and a driving assistance method that communicate vehicle behavior to a driver or the like in an easily understandable manner. The driving assistance device includes: a vehicle acceleration detection unit that detects vehicle acceleration, including lateral acceleration and longitudinal acceleration; a calculation unit that calculates, for each wheel, a friction circle, a lateral force generated on each wheel, and a longitudinal force generated on each wheel based on the detection results of the vehicle acceleration detection unit; and a display unit that displays, based on the calculation results of the calculation unit, an image of the friction circle and the resultant force of the lateral force and longitudinal force generated on each wheel, and the magnitude and / or direction of the resultant force.

Description

Technical Field

[0001] The present disclosure relates to a driving assistance device, a recording medium having a driving assistance program recorded thereon, and a driving assistance method. Background Art

[0002] Patent Document 1 discloses a driving assistance device that compares a friction circle with acceleration during driving. The friction circle is set to correspond to the acceleration limit of the vehicle's tire slippage and can be compared with the acceleration detected by an acceleration sensor. The driving assistance device includes an accelerometer that detects the acceleration generated by the vehicle during driving; a memory that stores acceleration boundary regions set before driving; a comparison unit that compares the acceleration detected by the accelerometer with the boundary regions during driving; and a reporting unit that reports the comparison results based on the comparison performed by the comparison unit during driving.

[0003] Patent Document 2 discloses a driving status display device that simultaneously displays the driving force of each wheel, calculated over time, and the magnitude and direction of vehicle acceleration that varies based on that driving force, for a moving vehicle. This driving status display device uses a simulated vehicle image on an in-vehicle display to display the vehicle's driving status. The simulated vehicle image displays at least the driving force of the front or rear wheels, and the magnitude and direction of vehicle acceleration, on or near the simulated vehicle image.

[0004] Prior art literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-168958

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2015-101310 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] Conventional technology compares a friction circle based on an acceleration setting set by the driver or other users with the actual measured acceleration. However, in reality, the limit of tire rollout acceleration varies significantly depending on the tire load, leaving room for improvement in accurately conveying vehicle behavior to the driver or other users. Furthermore, simply displaying the magnitude and direction of acceleration during vehicle travel fails to convey the degree to which tires are being used appropriately.

[0009] An object of the present invention is to provide a driving assistance device that communicates the behavior of a vehicle to a driver or the like in an easily understandable manner.

[0010] Means for solving problems

[0011] One embodiment of the present invention is a driving assistance device, characterized in that the driving assistance device includes: a vehicle information acquisition unit, which acquires information related to the state of the vehicle; a calculation unit, which calculates a friction circle for each wheel based on the acquisition result of the vehicle information acquisition unit; and a display unit, which displays an image of the friction circle based on each wheel.

[0012] Another embodiment of the present invention is a recording medium, which is a non-volatile computer-readable recording medium, recording a driving assistance program executed by a computer processor to grasp the behavior of a vehicle, wherein the driving assistance program causes the processor to function as the following units: a vehicle acceleration detection unit, which detects vehicle acceleration including lateral acceleration and longitudinal acceleration of the vehicle; a calculation unit, which calculates a friction circle for each wheel based on the detection result of the vehicle acceleration detection unit, and calculates a tire force as the magnitude of the resultant force and a tire friction direction as the direction of the resultant force for the resultant force of the lateral force generated by the tire of each wheel and the longitudinal force generated by the tire of each wheel; and a display unit, which displays the friction circle and an image based on the tire force and the tire friction direction for each wheel based on the calculation result of the calculation unit.

[0013] Another embodiment of the present invention is a driving assistance method, characterized in that the driving assistance method comprises: a vehicle acceleration detection step, detecting the vehicle acceleration including the lateral acceleration and the longitudinal acceleration of the vehicle; a calculation step, calculating the friction circle for each wheel based on the detection result of the vehicle acceleration detection step, and calculating the tire force as the magnitude of the resultant force and the tire friction direction as the direction of the resultant force for the lateral force generated by the tire of each wheel and the longitudinal force generated by the tire of each wheel; and a display step, displaying the friction circle and an image based on the tire force and the tire friction direction for each wheel based on the calculation result of the calculation step.

[0014] Effects of the Invention

[0015] The driving assistance device of the present invention has the effect of conveying the behavior of the vehicle to the driver in an easily understandable manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a block diagram of the driving assistance device according to the first embodiment.

[0017] Figure 2 This is the display image in the driving assistance device.

[0018] Figure 3 It is a warning display in the display image.

[0019] Figure 4 This is a display image of the second embodiment.

[0020] Figure 5 This is a block diagram of a driving assistance device according to a third embodiment.

[0021] Figure 6 This is a display image of embodiment 3.

[0022] Figure 7 This is a display image showing the steering characteristics.

[0023] Figure 8 This is a flowchart of the driving assistance method according to the fourth embodiment.

[0024] Description of Reference Numerals

[0025] 1…Driving assistance device, 5…Control unit, 7…Calculation unit, 8…Comparison operation unit, 9…Friction circle changing unit, 10…Display unit, 11…Display image, 12…Vehicle acceleration detection unit, 15…Tire friction display image, 20…Steering angle detection unit, 21…1G display circle, 22…Friction circle, 24…Maximum friction circle, 26…Second-timing resultant force indicator, 28…First-timing resultant force indicator, 32…Second-timing resultant force indicator, 34…Appropriate use display, 36…Warning display, 40…Center of gravity display, 42…Center of gravity, 44…Center of gravity trajectory, 50…Load display, 60…Steering characteristics display, 62…Understeer characteristics indicator, 64…Oversteer characteristics display. DETAILED DESCRIPTION

[0026] (Insights, etc. that form the basis of this disclosure)

[0027] When the inventors conceived of the present disclosure, there were driving assistance devices having a function such as a vehicle motion display for confirming the behavior of a vehicle while driving. This allows the behavior of the vehicle to be confirmed in real time or retrospectively.

[0028] However, there is no means for the driver to objectively judge whether the performance of the tire can be fully utilized, and the improvement of the skill for driving a vehicle mainly depends on the individual feeling of the driver.

[0029] Therefore, the present disclosure provides a driving assistance device, a driving assistance program, and a driving assistance method that can confirm the load applied to the tires, steering characteristics, and the like in real time or retrospectively after driving.

[0030] The following describes the embodiments in detail with reference to the accompanying drawings. However, excessive detail may be omitted. For example, detailed descriptions of well-known matters or repetitive descriptions of substantially identical structures may be omitted. This is to avoid excessive length in the following description and to facilitate understanding by those skilled in the art.

[0031] In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0032] (Implementation 1)

[0033] Below, use Figures 1 to 3 Implementation 1 will be described.

[0034] [1-1. Structure]

[0035] Figure 1 This is a block diagram of a driving assistance device 1 according to Embodiment 1. The driving assistance device 1 includes a vehicle acceleration detection unit 12 (acceleration sensor) as a vehicle information acquisition unit that detects vehicle acceleration, including lateral acceleration and longitudinal acceleration. Furthermore, the device includes a calculation unit 7 that calculates the friction circle, the lateral force generated in the tire, and the longitudinal force generated in the tire for each wheel based on the detection results of the vehicle acceleration detection unit 12; and a display unit 10 that displays an image based on the magnitude and / or direction of the resultant force of the friction circle and the resultant force of the lateral force and longitudinal force generated in each tire, based on the calculation results of the calculation unit 7.

[0036] Here, the friction circle corresponds to the limit value of the tire force calculated based on the road surface's coefficient of friction and the force generated by each tire. Specifically, the magnitude of the friction force between the road surface and the tire can be expressed as the radius of the friction circle. In this specification, the friction circle is displayed as a roughly circular plate. The size of the friction circle displayed on the display unit 10, specifically the radius of the friction circle, can be compared with the length of the display representing the net force generated by the tire.

[0037] However, the friction circle may be a perfect circle or an ellipse, or a combination of ellipses having different axis lengths.

[0038] Furthermore, while the vehicle acceleration detector is exemplified herein as a vehicle information acquisition unit, the present invention is not limited thereto. For example, a sensor that measures engine torque, brake fluid pressure, or the like may be used, and the forces generated in the tires may be estimated based on these. Alternatively, a sensor that directly measures the forces generated in the tires may be provided.

[0039] The calculation unit 7 can be implemented as a function of the control unit 5. Specifically, the control unit 5 is composed of a CPU, RAM, and ROM, and performs various controls through a processor. The CPU is a so-called central processing unit that executes various programs to implement various functions. The RAM is used as a working area and storage area of ​​the CPU, and the ROM is a recording medium that stores the operating system and programs executed by the CPU. Of course, as an alternative to the CPU, an MPU (Micro-Processing Unit) can also be used, and as the control unit 5, a wiring logic that cannot rewrite the program can also be used. If wiring logic is used as the control unit 5, it is effective for improving the processing speed. As wiring logic, there are ASICs (Application Specific Integrated Circuits), etc. In addition, the control unit 5 can be composed of one semiconductor element or a plurality of semiconductor elements. In the case of being composed of a plurality of semiconductor elements, each control described in the claims can also be implemented by different semiconductor elements. In addition, the control unit 5 can also be composed of a structure including semiconductor elements and passive components such as resistors or capacitors.

[0040] The calculation unit 7 calculates the force generated by each tire, specifically, the magnitude of the resultant force of the lateral force and the front and rear forces generated by the tire, i.e., the tire force, and the direction of the resultant force, i.e., the tire friction direction. The display unit 10 (display) displays the tire force calculated by the calculation unit 7 and an image that symbolically represents the tire friction direction. The display unit 10 can be a liquid crystal panel or an organic EL panel. In addition, the display unit 10 can also be provided on an onboard instrument or DA (display audio), or can be a screen on an information terminal such as a smart fan or a PC (personal computer) of the driver or fellow passengers in the vehicle. At this time, the control unit 5 and the information terminal can transmit and receive information wirelessly.

[0041] [1-2. Calculation method]

[0042] Here, the calculation method of the friction circle, tire force, and tire friction direction is briefly described. However, the calculation method described in this specification is for illustrative purposes only and does not limit the content of the claims. Various calculation methods are conceivable.

[0043] First, consider a coordinate system with the vertical direction as the Z axis, the front-to-back direction of the vehicle as the X axis, and the vehicle axis direction perpendicular to the X and Z axes as the Y axis. To calculate the friction circle of each tire, the friction coefficient μ of the road surface and the force F generated by each tire are required. Z When the vehicle is stationary, the force F generated on each tire is ZThe friction circle is determined by the balance of the weight of the vehicle and the load on the vehicle. Z The multiplication operation determines .

[0044] The friction coefficient μ also varies greatly depending on the condition of the road surface, specifically, when it is raining, snowing, or when the road surface is frozen, and also varies greatly depending on the amount of tire wear.

[0045] During driving, especially when turning, accelerating, or decelerating, the vehicle generates a force in the X-axis direction (front and rear force F X ) and the Y-axis force (lateral force F Y ). How much each tire is properly used can be defined by the relationship between the tire force, tire friction direction, and friction circle. Specifically, based on the front and rear force F X and lateral force F Y The degree to which the calculated tire force relative to the size of the friction circle is a measure of how close the tire is to its limit value, in other words, how much the tire is being used, can be used to determine the quality of the driving technique.

[0046] For example, assuming that the friction coefficients of the tire in the X-axis direction and the Y-axis direction are the same μ, the extent to which the tire's performance has been used can be expressed as a percentage according to equation (1).

[0047] [Mathematical formula 1]

[0048]

[0049] The force F generated at each tire Z For example, if the wheelbase length is L (wherein, for simplicity, the center of gravity is located at a position equidistant from the front and rear wheels), the tread width is d, the center of gravity height is h, the mass is M, the gravitational acceleration is g, and the acceleration detected by the vehicle acceleration detector 12 (see Figure 1 ) The acceleration in the X-axis direction is set as a X , set the acceleration in the Y-axis direction to a Y Assuming that the front-rear balance of the left and right load transfer is R, the force Fz generated in each tire is calculated by static balance, for example, as shown in mathematical formula (2).

[0050] [Mathematical formula 2]

[0051]

[0052] Here, the inertial force under the elastic force is not considered.

[0053] The front and rear forces F generated by each tire XIt can be estimated based on tire characteristics such as tire model and slip ratio, but this is rather complicated. Therefore, it can also be estimated approximately based on the acceleration in the X-axis direction. Specifically, if the influence of the drag force in the X-axis direction of the air acting on the vehicle is considered, the air density ρ, the vehicle speed V, the front projection area A, and the drag coefficient C are assumed to be d , then the basic front-rear force F generated in a tire X_Total Calculate as shown in formula (3).

[0054] [Mathematical formula 3]

[0055]

[0056] When an LSD (Limited Slip Differential: Differential Limiting Device) is installed to adjust the rotation difference between the inner and outer tires during acceleration, the longitudinal force F applied to one tire during acceleration is X_Acc As shown in the mathematical formula (4), the LSD driving force G coefficient is estimated as the acceleration a in the X and Y axis directions. Y .

[0057] [Formula 4]

[0058]

[0059] In addition, during braking, the front and rear force F generated by one tire X_Brake The coefficient representing the braking balance is set to B, and the front-rear force is estimated as shown in the mathematical formula (5) so that the same front-rear force is distributed to the left and right wheels.

[0060] [Formula 5]

[0061]

[0062] As the longitudinal force F generated at each tire X , you can use F when accelerating X_Acc , use F when braking X_Brake .

[0063] For the lateral force F generated on each tire Y , can also be simply based on the lateral acceleration a Y First, if the axle weight at the front of the vehicle is set to M f , let the vehicle's moment of inertia be I and the wheelbase length be L, then the lateral force F on the front tire is Y_Front It is estimated as shown in equation (6).

[0064] [Formula 6]

[0065]

[0066] Here, F Y The front-end and back-end distribution is equivalent to the 2-round model for calculation.

[0067] In addition, if the left and right are assigned F Z The factor that reduces the friction coefficient when the wheel load increases on the outer side of the inner tire is defined as the reduction rate ε of the friction coefficient. For example, when the force generated by the front left tire is defined as F Z_FL , the force generated by the front right tire is set to F Z_FR When the lateral force F is generated on the front left tire Y_FL It is estimated as shown in the following mathematical formula (7).

[0068] [Formula 7]

[0069]

[0070] By using the above-described estimation method, it is possible to estimate to what extent the performance of the tire is being exhausted.

[0071] [1-3. Action]

[0072] Figure 2 The figure shows an example of the display image 11 displayed on the display unit 10 of the driving assistance device 1. The display image 11 includes a tire friction display image 15A that displays information about the tire of the left front wheel (FL); a tire friction display image 15B that displays information about the tire of the right front wheel (FR); a tire friction display image 15C that displays information about the tire of the left rear wheel (RL); and a tire friction display image 15D that displays information about the tire of the right rear wheel (RR).

[0073] Tire friction display image 15 shows a 1G display circle 21, which represents the friction circle corresponding to the force generated by the tires when the vehicle is parked, and a maximum friction circle 24, which represents the friction circle when the tires assume maximum grip. The magnitude of maximum friction circle 24 may correspond to, for example, 9 kN for the front wheels and 6 kN for the rear wheels.

[0074] Furthermore, the friction coefficient μ varies significantly depending on road conditions, specifically, rain, snow, or frozen conditions, as well as tire wear. Therefore, the friction coefficient μ can be adjusted accordingly when calculating the size of friction circle 22. Furthermore, the control unit 5 may include a friction circle changing unit 9 for changing the size of friction circle 22. Specifically, a setting screen for changing the size of friction circle 22 is preferably displayed on the display unit 10, allowing the user to change the size of friction circle 22.

[0075] Of course, the driving assistance device can also obtain information about road conditions and tire wear, and the friction circle changing unit 9 can change the size of the friction circle 22. Specifically, the friction circle 22 can be calculated and displayed based on the road surface temperature and moisture content, the estimated friction coefficient μ based on the distance traveled since the tire was replaced, and other factors.

[0076] Furthermore, calculation unit 7 calculates the tire force and tire friction direction at a first timing and a second timing that is later than the first timing, respectively. Display unit 10 substantially simultaneously displays a first image representing the first tire force and first tire friction direction calculated at the first timing, and a second image representing the second tire force and second tire friction direction calculated at the second timing. Furthermore, the number of timings and the number of images representing the tire friction amount and tire friction direction calculated at each timing can be arbitrarily set.

[0077] Specifically, in tire friction display image 15A, which displays information about the left front wheel's tire, the resultant force (i.e., the second tire force) and the second tire friction direction, resulting from the most recent measurement corresponding to the second timing, are indicated by arrows as second-timing resultant force indicator 26. The resultant force (i.e., the second tire force) and the second tire friction direction, resulting from the first timing measurement 100 milliseconds prior to the second timing, are indicated as first-timing resultant force indicator 28. The length of the arrow corresponds to the magnitude of the resultant force, specifically the tire force, and the direction of the arrow corresponds to the direction of the resultant force, specifically the tire friction direction. Tire friction display image 15 can have a sampling interval of, for example, 100 milliseconds, with the display changing every 100 milliseconds. Furthermore, when displaying images from multiple timings, data from earlier timings can be displayed with decreasing brightness. Alternatively, different colors can be used for each timing. Furthermore, after a specified period of time, data from past timings can be deleted from display image 11.

[0078] Furthermore, the driving assistance device 1 includes a comparison calculation unit 8 for comparing the tire force with the size of the friction circle. Based on the comparison result of the comparison calculation unit 8, the display unit 10 notifies the user of the first state when the tire force is within a predetermined range, i.e., within the size of the friction circle 22. The first state is a value calculated using the mathematical formula (1), for example, between 80% and 100%.

[0079] Specifically, in tire friction display image 15B, when the size of resultant force indicator 32 reaches 80% or more and 100% or less of the radius of friction circle 22 at the second timing, the tire is determined to be properly used, and preferred use indicator 34 is displayed. In other words, when the value in equation (1) is 80% or more and 100% or less, the driver is informed that driving that utilizes the tire's performance is possible. Preferred use indicator 34 can be illuminated, for example, by emitting a green light on the outer periphery of maximum friction circle 24.

[0080] In addition, the display image 11 includes a center of gravity indicator 40 that displays the center of gravity of the vehicle or the magnitude and direction of acceleration at the center of gravity of the vehicle. The center of gravity indicator 40 can display a center of gravity 42 indicating the position of the center of gravity and a center of gravity trajectory 44 indicating its temporal change.

[0081] Furthermore, the control unit 5 of the driving assistance device 1 may include a recording unit (not shown) that continuously records information about the friction circle 22, the resultant force indicator, and the preferred use indicator 34 over time. Specifically, the recording unit may be an SSD (solid-state drive) or an HDD (hard disk drive). After driving, the driver can retrieve the information from the recording unit and display it on the display unit 10, etc., allowing them to objectively review their driving experience. Of course, the information can also be transferred to an information device such as a smartphone or PC (personal computer) for analysis.

[0082] Figure 3 Warning sign 36 is shown in display image 11. Based on the comparison result of comparison operation unit 8, display unit 10 notifies the user of the second state when the tire force exceeds the size of friction circle 22. The second state refers to a state where the tire usage exceeds the tire limit.

[0083] Specifically, when the length of the second timing resultant force indicator 32 is greater than the size of the friction circle 22, that is, when the magnitude of the resultant force generated by the tires, i.e., the tire force, exceeds the tire's limit value, and the possibility of slip increases, the control unit 5 controls the display unit 10 to display a warning indicator 36. The warning indicator 36 can be displayed overlapping the tire friction display image 15 of the corresponding tire. For example, the warning indicator 36 can be displayed as a red disk image overlapping the tire friction display image 15. A warning sound can also be generated at this time.

[0084] Furthermore, the control unit 5 may include a display setting change mode in which the user can enlarge or reduce the size of the friction circle 22 and the image representing the tire force and tire friction direction displayed on the display unit 10. Specifically, if the friction circle 22 is small, it is preferable to enlarge both the friction circle and the image representing the net force generated by the tire. To achieve this, the display unit 10 may be a touchscreen panel, allowing the image to be enlarged by sliding, or the magnification factor may be selectable.

[0085] [1-4. Effects, etc.]

[0086] The driving assistance device 1 according to the present disclosure includes a vehicle information acquisition unit that acquires information related to the vehicle state; a calculation unit 7 that calculates a friction circle for each wheel based on the acquisition result of the vehicle information acquisition unit; and a display unit 10 that displays an image based on the friction circle of each wheel.

[0087] This allows the driver and fellow passengers to visually recognize the limits of the forces on each tire, and thus achieves an excellent effect of enabling more accurate driving.

[0088] The driving assistance device 1 according to the present disclosure includes a friction circle changing unit 9 that changes the size of the friction circle.

[0089] This allows calculation and display of a friction circle reflecting the friction coefficient μ, which varies significantly depending on road conditions, specifically rain, snow, and frozen conditions, as well as tire wear. This allows users to easily visually obtain information that better matches the conditions.

[0090] In the driving assistance device 1 of the present disclosure, the vehicle information acquisition unit is a vehicle acceleration detection unit that detects vehicle acceleration including lateral acceleration and longitudinal acceleration.

[0091] Many vehicles already have accelerometers installed and can utilize them, eliminating the need for a new, specialized sensor. Accelerometers are inexpensive and highly accurate, enabling the highly accurate determination of the friction circle. Furthermore, drivers and passengers can easily and quantitatively identify the tire friction direction (described later), resulting in more accurate driving.

[0092] In the driving assistance device 1 disclosed herein, the calculation unit 7 calculates, for each wheel, the tire force as the magnitude of the resultant force of the lateral force generated by the tire of each wheel and the front-rear force generated by the tire of each wheel based on the vehicle acceleration, and the display unit 10 displays the tire force and tire friction direction calculated by the calculation unit 7 as an image.

[0093] This allows the driver and fellow passengers to visually recognize the usage status of each tire, resulting in an excellent effect of enabling more accurate driving.

[0094] In the driving assistance device 1 involved in the present disclosure, the calculation unit 7 calculates the tire force and the tire friction direction at a first timing and a second timing which is a moment later than the first timing, respectively, and the display unit 10 displays a first image showing the first tire force and the first tire friction direction calculated at the first timing, and a second image showing the second tire force and the second tire friction direction calculated at the second timing approximately simultaneously.

[0095] This allows the driver and fellow passengers to continuously monitor tire usage over time. For example, by observing information during circuit driving, they can gain insights into how to maximize the vehicle's performance, thereby improving their driving skills.

[0096] In the driving assistance device 1 according to the present disclosure, when the display unit 10 displays the second image, the second image is displayed in a color different from that of the first image.

[0097] This makes it easier for the driver and fellow passengers to visually recognize the latest tire conditions, thereby enabling more appropriate operation.

[0098] In the driving assistance device 1 according to the present disclosure, when the display unit 10 displays the second image, the first image is not displayed when a predetermined time has elapsed since the first image was displayed.

[0099] This makes it easier for the driver and fellow passengers to visually recognize the latest tire conditions, thereby enabling more appropriate driving.

[0100] The driving assistance device 1 according to the present disclosure includes a comparison calculation unit 8 that compares the tire force with the size of the friction circle 22 .

[0101] This allows comparison of the tire's usage status and the tire's ultimate performance, making it possible to identify how well the driver is utilizing the vehicle's performance through their own driving skills.

[0102] In the driving assistance device 1 according to the present disclosure, when the tire force is in a predetermined first state within a range not exceeding the size of the friction circle 22 based on the comparison result of the comparison operation unit 8 , the display unit 10 notifies the user of the first state.

[0103] This allows the driver to recognize that the vehicle is in a predetermined state. Specifically, the driver can confirm whether the tire's maximum performance is being utilized through his or her driving skills, thereby improving the driver's driving skills.

[0104] In the driving assistance device 1 according to the present disclosure, when the tire force exceeds the friction circle 22 in the second state based on the comparison result of the comparison operation unit 8 , the display unit 10 notifies the user of the second state.

[0105] This allows the driver and fellow passengers to recognize that they have exceeded the tire's performance limit, thereby preventing dangerous driving and providing guidance on improving their driving skills.

[0106] The driving assistance device 1 according to the present disclosure has a display setting change mode in which a user can enlarge / reduce the size of the friction circle 22 and the image showing the tire force and tire friction direction displayed on the display unit 10 .

[0107] This allows the driver to easily visually check the magnitude of the tire force even when the tire's limit value is low, thereby avoiding dangerous driving and providing guidance on improving their driving skills.

[0108] (Implementation Method 2)

[0109] Below, use Figure 4 Implementation method 2 will be described.

[0110] [2-1. Structure]

[0111] Figure 4 Display image 11 of Embodiment 2 is shown. In this embodiment, load indicators 50 indicating the forces generated by each tire are provided in place of center of gravity indicator 40. Specifically, calculation unit 7 calculates the magnitude of the load applied to each tire, and display unit 10 displays the magnitude of the load for each tire. The remaining configuration and calculation methods for the values ​​of the elements of each indicator are the same as those of Embodiment 1, and therefore are omitted for clarity.

[0112] [2-2. Action]

[0113] Next, the action is explained. Figure 4 In the case of , the load is moved when the vehicle turns right in the figure while braking. In this case, the load is moved to the tire on the front side by the braking action.

[0114] In this case, an illustration of a vehicle may be drawn at the center of the display image 11 , and friction circles corresponding to the respective tires may be arranged near the tires.

[0115] The greater the load, the brighter the display. In addition, it is possible to differentiate by color, so that when the load applied to the tire is less than the average load applied to each tire when the vehicle is stationary, it is differentiated in blue, and when the load applied to the tire is greater than the average load applied to each tire when the vehicle is stationary, it is differentiated in red. In addition, the size of the load can be represented by a one-dimensional bar graph. Figure 4 In the case of , a load marker 50A indicating the load on the front left tire and a load marker 50B indicating the load on the front right tire are highlighted.

[0116] [2-3. Effects, etc.]

[0117] In the driving assistance device 1 of the present disclosure, the calculation unit 7 calculates the magnitude of the load applied to each wheel, and the display unit 10 displays the magnitude of the load applied to each wheel.

[0118] This makes it easy to understand how the load is applied to each wheel, so that the driver and fellow passengers can easily recognize the driving situation.

[0119] (Implementation 3)

[0120] Below, use Figures 5 to 7 Implementation method 3 will be described.

[0121] [3-1. Structure]

[0122] Figure 5 This is a block diagram of the driving assistance device 1 according to Embodiment 3. The control unit 5 includes a steering angle detection unit 20 (steering angle sensor) that detects the steering angle of the steering wheel. The remaining configuration is the same as that of Embodiment 1, and therefore description thereof is omitted.

[0123] Figure 6 Display image 11 of embodiment 3 is shown. A steering characteristic indicator 60 indicating steering characteristics is included, for example, in the lower center portion of display image 11. Steering characteristics refer to the relationship between steering wheel operation and vehicle behavior. Specifically, they indicate the characteristics of the vehicle when changing direction. Steering characteristics are categorized into understeer (US), where the turning radius increases as speed increases; oversteer (OS), where the turning radius decreases as speed increases; and neutral steering, where the turning radius remains unchanged even when speed changes. These characteristics can generally be changed by adjusting settings such as the suspension.

[0124] [3-2. Action]

[0125] The change in turning radius can generally be expressed by the stability coefficient, the difference in slip angles between the front and rear tires, and other factors. Here, the stability coefficient is used as an example for explanation. Specifically, it is determined by the relationship between the tire yaw stiffness K, the proportionality coefficient between the sideslip angle β and the magnitude of the lateral force F generated by each tire, and the distance from the center of gravity to the front and rear axles. A positive stability coefficient indicates a vehicle US, while a negative stability coefficient indicates an OS.

[0126] In the present embodiment, the display image 11 displayed on the display unit 10 includes a steering characteristic indicator 60 reflecting the stability coefficient.

[0127] Figure 7 An example of a steering characteristic indicator 60 is shown. In this embodiment, the magnitude of the stability coefficient is displayed using a one-dimensional bar graph. When the stability coefficient is positive, i.e., in an understeering state, the steering characteristic indicator 60 illuminates understeering characteristic indicators 62A, 62B, and 62C, indicating the US side, thereby notifying the driver and passengers that the steering characteristics are US. Furthermore, when the stability coefficient is negative, i.e., in an oversteering state, the steering characteristic indicator 60 illuminates oversteering characteristic indicators 64A and 64B, indicating the OS side, thereby notifying the driver and passengers that the steering characteristics are US.

[0128] [3-3. Effects, etc.]

[0129] The driving assistance device 1 according to the present disclosure includes a steering angle detection unit 20 that detects a steering angle of a vehicle, a calculation unit 7 that calculates a steering characteristic of the vehicle based on vehicle acceleration and the steering angle, and a display unit 10 that displays the steering characteristic.

[0130] This allows the driver and fellow passengers to visually recognize the vehicle's steering characteristics, enabling the driver to drive appropriately in accordance with the steering characteristics and improve driving skills.

[0131] Regarding the above-mentioned embodiments 1 to 3, in order for the user (specifically, for example, the driver) to understand the behavior of the vehicle, it can also be achieved through a driving assistance program, which is used to enable the computer to function as the following units: a vehicle acceleration detection unit, which detects the vehicle acceleration including the lateral acceleration and the longitudinal acceleration of the vehicle; a calculation unit, which calculates the friction circle, the lateral force generated on the tire, and the longitudinal force generated on the tire for each wheel based on the detection results of the vehicle acceleration detection unit; and a display unit, which displays an image based on the magnitude and / or direction of the resultant force of the friction circle and the resultant force of the lateral force and the longitudinal force generated on each tire based on the calculation results of the calculation unit.

[0132] (Implementation 4)

[0133] Below, use Figure 8 Implementation method 4 is described.

[0134] Figure 8 : is a flowchart of the driving assistance method disclosed in the present invention. First, the vehicle acceleration, including the lateral acceleration and the longitudinal acceleration of the vehicle, is detected (step S1). Next, the friction circle is calculated for each tire based on the detection result of step S1 (step S2). Based on the detection result, the lateral force generated on the tire and the longitudinal force generated on the tire are calculated for each tire (step S3). Then, the friction circle and the following image are displayed for each tire, which is an image of the tire friction direction as the direction of the resultant force of the lateral force and the longitudinal force generated by each tire, based on the tire force as the magnitude of the resultant force and the direction of the tire friction as the direction of the resultant force (step S4).

[0135] According to the driving assistance method of the present disclosure, the driver and fellow passengers can visually recognize the usage status of each tire, thereby achieving an excellent effect of enabling more accurate driving.

[0136] As described above, embodiments 1 to 4 have been described as examples of the technology disclosed in this application. However, the technology disclosed in this application is not limited thereto and can be applied to embodiments that have been modified, replaced, added, or omitted. In addition, the components described in embodiments 1 to 4 can be combined to form new embodiments.

[0137] [Structure supported by the above-mentioned embodiment]

[0138] The above-mentioned embodiment is a specific example of the following structure.

[0139] (Structure 1) A driving assistance device, characterized in that it includes: a vehicle information acquisition unit that acquires information related to the state of the vehicle; a calculation unit that calculates a friction circle for each wheel based on the acquisition result of the vehicle information acquisition unit; and a display unit that displays an image of the friction circle based on each wheel.

[0140] (Configuration 2) The driving assistance device according to Configuration 1 is characterized in that it includes a friction circle changing unit that changes the size of the friction circle.

[0141] (Configuration 3) The driving assistance device according to Configuration 1 or Configuration 2 is characterized in that the vehicle information acquisition unit is a vehicle acceleration detection unit that detects vehicle acceleration including lateral acceleration and longitudinal acceleration.

[0142] (Structure 4) The driving assistance device according to Structure 3 is characterized in that the calculation unit calculates, for each wheel, a tire force as the magnitude of the resultant force of the lateral force generated by the tire of each wheel and a front-rear force generated by the tire of each wheel based on the vehicle acceleration, and a tire friction direction as the direction of the resultant force, and the display unit displays the tire force and the tire friction direction calculated by the calculation unit as an image.

[0143] (Structure 5) The driving assistance device according to Structure 4 is characterized in that the calculation unit calculates the tire force and the tire friction direction for each wheel at a first timing and a second timing which is a moment later than the first timing, and the display unit displays a first image and a second image approximately simultaneously, wherein the first image shows the first tire force and the first tire friction direction calculated at the first timing, and the second image shows the second tire force and the second tire friction direction calculated at the second timing.

[0144] (Configuration 6) The driving assistance device according to Configuration 5, wherein the display unit displays the second image in a color different from that of the first image.

[0145] (Configuration 7) The driving assistance device according to Configuration 5 or Configuration 6 is characterized in that, when the display unit displays the second image, it no longer displays the first image when a predetermined time has passed since the first image was displayed.

[0146] (Structure 8) The driving assistance device according to any one of Structures 4 to 7 is characterized in that the driving assistance device includes a comparison operation unit that compares the tire force with the size of the friction circle.

[0147] (Structure 9) The driving assistance device according to Structure 8 is characterized in that, based on the comparison result of the comparison operation unit, when the tire force is in a range that does not exceed the size of the friction circle, that is, in a predetermined first state, the display unit reports to the user that it is in the first state.

[0148] (Structure 10) The driving assistance device according to Structure 8 or Structure 9 is characterized in that, based on the comparison result of the comparison operation unit, when the tire force is in the second state exceeding the size of the friction circle, the display unit reports to the user that it is in the second state.

[0149] (Structure 11) The driving assistance device according to any one of Structures 4 to 10 is characterized in that the driving assistance device has a display setting change mode, in which the user enlarges or reduces the size of the friction circle displayed on the display unit and the image showing the tire force and the tire friction direction.

[0150] (Structure 12) The driving assistance device according to any one of Structures 3 to 11, wherein the calculation unit calculates the magnitude of the load applied to each wheel, and the display unit displays the magnitude of the load for each wheel.

[0151] (Structure 13) The driving assistance device according to any one of Structures 3 to 12 is characterized in that the driving assistance device includes a steering angle detection unit, which detects the steering angle of the steering wheel in the vehicle, the calculation unit calculates the steering characteristics of the vehicle based on the vehicle acceleration and the steering angle, and the display unit displays the steering characteristics.

[0152] (Structure 14) A recording medium, which is a non-volatile computer-readable recording medium, recording a driving assistance program executed by a processor of a computer in order to grasp the behavior of a vehicle, wherein the driving assistance program causes the processor to function as the following units: a vehicle acceleration detection unit, which detects the vehicle acceleration including the lateral acceleration and the longitudinal acceleration of the vehicle; a calculation unit, which calculates a friction circle for each wheel based on the detection result of the vehicle acceleration detection unit, and calculates a tire force as the magnitude of the resultant force and a tire friction direction as the direction of the resultant force for the resultant force of the lateral force generated by the tire of each wheel and the longitudinal force generated by the tire of each wheel; and a display unit, which displays the friction circle and an image based on the tire force and the tire friction direction for each wheel based on the calculation result of the calculation unit.

[0153] (Structure 15) A driving assistance method, characterized in that the driving assistance method comprises: a vehicle acceleration detection step for detecting the vehicle acceleration including the lateral acceleration and the front-rear acceleration of the vehicle; a calculation step for calculating the friction circle for each wheel based on the detection result of the vehicle acceleration detection step, and for the resultant force of the lateral force generated by the tire of each wheel and the front-rear force generated by the tire of each wheel, calculating the tire force as the magnitude of the resultant force and the tire friction direction as the direction of the resultant force; and a display step for displaying the friction circle and an image based on the tire force and the tire friction direction for each wheel based on the calculation result of the calculation step.

Claims

1. A driving assistance device comprising a processor, characterized in that: The processor performs the following processing: Obtain information related to the status of the vehicle; Based on the obtained results, the friction circle of each wheel is calculated; displaying an image of the friction circle based on each wheel on a display; Detect vehicle acceleration including lateral acceleration and front-to-back acceleration; Calculating a tire force and a tire friction direction of each wheel based on the detected vehicle acceleration, wherein the tire force is a resultant of a lateral force generated by a tire associated with each wheel and a fore-aft force generated by a tire associated with each wheel; displaying the tire force and the tire friction direction as a first image on the display; performing a comparison operation to compare the tire force with the size of the friction circle; displaying a depiction of the first state on the display when a predetermined first state is determined based on the comparison result of the comparison operation, the first state being a state in which the tire force is within a range that does not exceed the size of the friction circle; When a predetermined second state is determined based on the comparison result of the comparison operation, displaying a depiction of the second state on the display, the second state being a state where the tire force exceeds the size of the friction circle; Being able to obtain the center of gravity position of the vehicle; displaying a center-of-gravity position of the vehicle and a center-of-gravity trajectory indicating a temporal change in the center-of-gravity position as a second image; On the display, the first image and the second image are displayed in different areas in a corresponding manner.

2. The driving assistance device according to claim 1, wherein: The processor changes the size of the friction circle.

3. The driving assistance device according to claim 1, wherein: The processor has a display setting change mode in which a user enlarges or reduces the size of the friction circle displayed on the display and the image showing the tire force and the tire friction direction.

4. The driving assistance device according to claim 1, wherein: The processor calculates the magnitude of the load applied to each wheel. The magnitude of the load is displayed on the display for each wheel.

5. The driving assistance device according to claim 1, wherein: The processor detects a steering angle of a steering wheel in the vehicle, the processor calculating a steering characteristic of the vehicle based on the vehicle acceleration and the steering angle, The steering characteristic is displayed on the display.

6. A driving assistance method, characterized in that: The driving assistance method comprises the following steps: A vehicle acceleration detection step of detecting the vehicle acceleration including the lateral acceleration and the front-rear acceleration of the vehicle; a calculation step of calculating a friction circle for each wheel based on the detection result of the vehicle acceleration detection step, and calculating a tire force as the magnitude of a resultant force of a lateral force generated by the tire of each wheel and a longitudinal force generated by the tire of each wheel, and a tire friction direction as the direction of the resultant force; a display step of displaying, based on the calculation result of the calculation step, the friction circle and a first image based on the tire force and the tire friction direction for each wheel on a display; performing a comparison operation to compare the tire force with the size of the friction circle; displaying a depiction of the first state on the display when a predetermined first state is determined based on the comparison result of the comparison operation, the first state being a state in which the tire force is within a range that does not exceed the size of the friction circle; When a predetermined second state is determined based on the comparison result of the comparison operation, displaying a depiction of the second state on the display, the second state being a state where the tire force exceeds the size of the friction circle; Obtaining the center of gravity position of the vehicle; displaying, on the display, a center-of-gravity position of the vehicle and a center-of-gravity trajectory indicating temporal changes in the center-of-gravity position as a second image; On the display, the first image and the second image are displayed in different areas in a corresponding manner.

Images