Vehicle control system, vehicle

Abstract

It accurately estimates the condition of the road surface in contact with each of the vehicle's drive wheels. [Solution] The vehicle control device 1 includes a torque command output unit 30 that outputs a torque command T for the braking and driving torque of the drive wheels, an instantaneous torque command output unit 110 that outputs an instantaneous torque command Ts for the instantaneous torque superimposed on the braking and driving torque, a drive control unit 130 that performs driving control of the drive wheels based on the torque command T and the instantaneous torque command Ts, and a road surface condition estimation unit 120 that estimates the condition of the road surface in contact with the drive wheels based on the rotational speed ω of the drive wheels when the instantaneous torque command output unit 110 outputs the instantaneous torque command Ts.

Description

Technical Field

[0001] The present invention relates to a vehicle control device that controls a vehicle, and a vehicle controlled by the vehicle control device.

Background Art

[0002] In vehicles including electric vehicles, there are increasing demands for improving the riding comfort and safe driving according to road surface conditions. To achieve this, a technique has been proposed in which the slip ratio of drive wheels is estimated based on the torque and rotational state of each of the plurality of drive wheels of the vehicle, and vehicle control is performed according to the estimation result (Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the method of Patent Document 1, the slip ratio is estimated by calculating an ordinary differential equation using the calculated values of the rotational speed and rotational acceleration of the drive wheel and the torque measurement value of the motor that drives the drive wheel. Therefore, when the road surface conditions are different for each drive wheel, there is a problem that it becomes difficult to estimate the slip ratio.

[0005] In Patent Document 2, information corresponding to the vertical force on each of the plurality of drive wheels is acquired, and based on the acquisition result, friction coefficient information regarding each of the plurality of drive wheels is calculated, and the slip ratio of each drive wheel is calculated. Therefore, similar to Patent Document 1, when the road surface conditions are different for each drive wheel, there is a problem that it becomes difficult to estimate the slip ratio.

[0006] In view of the above problems, the present invention aims to provide a technology that can accurately estimate the condition of the road surface in contact with each drive wheel of a vehicle. [Means for solving the problem]

[0007] The vehicle control device according to the present invention controls a vehicle having one or more drive wheels and comprises: a torque command output unit that outputs a torque command for the braking and driving torque of the drive wheel; an instantaneous torque command output unit that outputs an instantaneous torque command for the instantaneous torque superimposed on the braking and driving torque; a drive control unit that performs driving control of the drive wheel based on the torque command and the instantaneous torque command; and a road surface condition estimation unit that estimates the condition of the road surface in contact with the drive wheel based on the rotational speed of the drive wheel when the instantaneous torque command output unit outputs the instantaneous torque command. The vehicle according to the present invention comprises a vehicle control device and one or more drive wheels that are driven and controlled by the vehicle control device. [Effects of the Invention]

[0008] According to the present invention, the condition of the road surface in contact with each drive wheel of a vehicle can be accurately estimated.

[0009] Furthermore, issues, configurations, and effects other than those mentioned above will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0010] [Figure 1] A block diagram showing the configuration of a vehicle control device according to the first embodiment of the present invention. [Figure 2] A diagram illustrating an example of the relationship between longitudinal forces acting on the drive wheels of a vehicle and the slip ratio. [Figure 3] A diagram showing an example of an instantaneous torque command. [Figure 4] This diagram shows the relationship between the longitudinal force applied to the drive wheel and the slip ratio, with the coefficient of friction μ as a parameter. [Figure 5]A diagram showing the relationship between the coefficient of friction μ and the slip ratio λ for different road surface conditions. [Figure 6] A block diagram showing the configuration of a vehicle control device according to a second embodiment of the present invention. [Figure 7] A diagram showing an example of a vehicle equipped with a vehicle control device according to a second embodiment of the present invention. [Figure 8] A diagram illustrating an example of a vehicle vibration control method. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the drawings. The following description and drawings are illustrative for illustrating the present invention, and have been omitted and simplified as appropriate for clarity of explanation. The present invention can also be carried out in various other forms. Unless otherwise specified, each component may be singular or plural.

[0012] The positions, sizes, shapes, and ranges of the components shown in the drawings may not represent their actual positions, sizes, shapes, and ranges in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the positions, sizes, shapes, and ranges disclosed in the drawings.

[0013] (First embodiment) Figure 1 is a block diagram showing the configuration of a vehicle control device according to a first embodiment of the present invention. The vehicle control device 1 shown in Figure 1 is a device that is mounted on an electric vehicle driven by an electric motor, for example, and controls the vehicle. The vehicle control device 1 is configured using an ECU (Electronic Control Unit), and its functions include an operation information output unit 10, a request level specification unit 20, a torque command output unit 30, and a drive wheel control unit 100.

[0014] The operation information output unit 10 detects the driving operations of the vehicle performed by the driver (e.g., steering operation, accelerator operation, brake operation, etc.) and outputs operation information Drv representing the content thereof. The operation information Drv corresponding to the driving operation of the vehicle output from the operation information output unit 10 is input to the required level specifying unit 20 and the torque command output unit 30, respectively.

[0015] Based on the operation information Drv input from the operation information output unit 10, the required level specifying unit 20 determines the required level for the estimated result of the road surface condition and outputs a required signal S corresponding to the required level. Thereby, the required level for the estimation of the road surface condition performed by the vehicle control device 1 is specified. Details of the method for determining the required level by the required level specifying unit 20 will be described later.

[0016] Based on the operation information Drv input from the operation information output unit 10, the torque command output unit 30 outputs a torque command T for the driving and braking torque of the driving wheels of the vehicle. For example, in order to realize the motion state of the vehicle corresponding to the operation information Drv, the magnitude of the driving and braking torque that the electric motor for driving mounted on the vehicle should output to the driving wheels is output as the torque command T.

[0017] The drive wheel control unit 100 includes an instantaneous torque command output unit 110, a road surface condition estimation unit 120, and a drive control unit 130.

[0018] The instantaneous torque command output unit 110 outputs an instantaneous torque command Ts for the instantaneous torque superimposed on the driving and braking torque of the driving wheels. Thereby, the driving and braking torque of the driving wheels is varied in a short time, and the state of the driving wheels at that time is observed, so that the state of the road surface with which the driving wheels are in contact can be estimated. Details of the instantaneous torque command Ts output by the instantaneous torque command output unit 110 will be described later.

[0019] The road surface condition estimation unit 120 acquires the rotational speed ω of the drive wheel when the instantaneous torque command output unit 110 outputs an instantaneous torque command Ts, and estimates the condition of the road surface in contact with the drive wheel based on this rotational speed ω. Then, it outputs road surface condition information I representing the estimation result to the torque command output unit 30. The rotational speed ω of the drive wheel can be calculated, for example, based on the time change of the rotation angle signal of an electric motor output from a rotation angle sensor such as a resolver. Alternatively, the rotational speed ω of the drive wheel may be determined from the signal output from a wheel speed sensor installed on the drive wheel.

[0020] The torque command output unit 30 adjusts the value of the torque command T based on the road surface condition information I input from the road surface condition estimation unit 120. This outputs braking and driving torque to the drive wheels according to the road surface condition, enabling the vehicle to run stably.

[0021] The drive control unit 130 receives a combined torque command T+Ts, which is the sum of the torque command T and the instantaneous torque command Ts. Based on this combined torque command T+Ts, the drive control unit 130 outputs a braking and driving torque To for the drive wheels. As a result, the drive of the drive wheels is controlled using a value obtained by superimposing the instantaneous torque command Ts onto the torque command T.

[0022] In this embodiment, the vehicle control device 1 is mounted on the vehicle, for example, for each drive wheel. That is, in the case of an electric motorcycle with one drive wheel, one vehicle control device 1 as shown in Figure 1 is mounted, and this vehicle control device 1 is used to control the drive of the drive wheel. In the case of an electric vehicle with two or four drive wheels, the same number of vehicle control devices 1 as the number of drive wheels are mounted, and each vehicle control device 1 is used to control the drive of each drive wheel.

[0023] Vehicles equipped with the vehicle control device 1 of this embodiment include, for example, in-wheel type vehicles in which electric motors are mounted inside the wheels, but onboard type vehicles in which electric motors are mounted on the vehicle body are also acceptable. Furthermore, the vehicle control device 1 of this embodiment can be applied even when a ball joint or reduction gear is arranged between the electric motor and the wheel. Preferably, if the vehicle is a four-wheel drive in-wheel vehicle in which all four wheels of an electric vehicle are driven wheels, it is possible to obtain the advantage of providing a large amount of interior space while performing stable vehicle control.

[0024] Next, the details of how the requirement level is determined by the requirement level specification unit 20 will be explained below.

[0025] As described above, the request level specification unit 20 determines the request level for the estimated road surface condition based on the operation information Drv and outputs a request signal S. This request level can be determined, for example, according to the driver's driving operation of the vehicle as represented by the operation information Drv. Specifically, for example, when the vehicle is traveling at a constant speed on a road surface with a relatively high coefficient of friction, such as a dry asphalt road, there is no need to estimate the road surface condition with high accuracy, so the request level is set low and the request signal S is output. In response to this request signal S, the magnitude of the instantaneous torque command Ts output by the instantaneous torque command output unit 110 is zero or a relatively small value. In this way, when there is no need to estimate the road surface condition with high accuracy, the effects of vehicle vibration due to the superposition of instantaneous torque can be reduced.

[0026] On the other hand, when a vehicle is traveling on a road surface with a relatively low coefficient of friction, such as an icy road, or when the driver is performing steering or braking operations, it is necessary to estimate the road surface condition with high accuracy to stabilize the vehicle's movement. Therefore, the requirement level is set high and a request signal S is output. The instantaneous torque command Ts output by the instantaneous torque command output unit 110 in response to this request signal S is larger than when the requirement level is low. In this way, the accuracy of the road surface condition estimation by the road surface condition estimation unit 120 can be improved.

[0027] The road surface condition estimation unit 120 estimates the condition of the road surface in contact with the drive wheels, for example, the slip ratio λ of the drive wheels. This estimated slip ratio λ is input from the road surface condition estimation unit 120 to the torque command output unit 30 as road surface condition information I.

[0028] When the slip ratio λ is below a predetermined value, the torque command output unit 30 outputs the value of the braking and driving torque corresponding to the driver's accelerator and brake operations as a torque command T to the drive control unit 130. In this case, the drive control unit 130 only needs to transmit a braking and driving torque To equivalent to the torque command T to the drive wheels. On the other hand, if the slip ratio λ exceeds a predetermined value, outputting the value of the braking and driving torque corresponding to the driver's accelerator and brake operations as a torque command T would further increase the slip ratio λ of the drive wheels, potentially resulting in a loss of vehicle control. Therefore, in this case, the torque command output unit 30 adjusts the torque command T so that the slip ratio λ is predetermined, thereby achieving stable vehicle control regardless of road surface conditions.

[0029] Next, the instantaneous torque command Ts output by the instantaneous torque command output unit 110 and the details of the road surface condition estimation method by the road surface condition estimation unit 120 will be explained below.

[0030] Figure 2 shows an example of the relationship between the longitudinal force acting on the drive wheels of a vehicle and the slip ratio. In Figure 2, the longitudinal force acting on the drive wheels of a moving vehicle is shown on the vertical axis, and the slip ratio is shown on the horizontal axis.

[0031] In Figure 2, if the slip ratio λ is the vertical force acting on the drive wheel F, then this slip ratio λ is expressed by the following equation (1). In equation (1), ω represents the rotational speed of the drive wheel, V represents the moving speed of the drive wheel, and R represents the radius of the drive wheel. λ=(Rω-V) / Rω ···(1)

[0032] When a vehicle is traveling on a straight road, the speed V of the drive wheels is approximately equivalent to the vehicle's travel speed. Therefore, if the actual vehicle's travel speed can be detected, this can be used as the drive wheel speed V, and the slip ratio λ can be estimated using equation (1). However, during cornering, the vehicle's travel speed and the drive wheel speed V do not necessarily coincide. Furthermore, during acceleration and deceleration, the center of gravity shifts on the drive wheels, causing deformation of the drive wheel tires. Due to these effects, estimating the slip ratio λ using equation (1) with the vehicle's travel speed as the drive wheel speed V results in a large estimation error.

[0033] Therefore, in the vehicle control device 1 of this embodiment, even if there is a change in the torque of the drive wheels, if the change is short-term, the moving speed V of the drive wheels can be considered constant based on the magnitude of the vehicle's inertia, and the slip ratio λ is estimated as follows.

[0034] Figure 3 shows an example of an instantaneous torque command output by the instantaneous torque command output unit 110. In Figure 3, the horizontal axis represents time, and the vertical axis represents the magnitude of the torque represented by the instantaneous torque command Ts.

[0035] When a torque in the acceleration direction is superimposed on the drive wheels for a short period of time Ta while the vehicle is in motion, let ωa be the rotational speed of the drive wheels, and let ΔF be the change (increase) in the force acting longitudinally on the drive wheels. At this time, as shown in Figure 2, the slip ratio λ increases by the change amount Δλa and changes to slip ratio λa. This changed slip ratio λa is expressed by the following equation (2). λa=λ+Δλa=(Rωa-V) / Rωa ···(2)

[0036] In equation (2), the change in slip ratio Δλa is added as a new unknown variable compared to equation (1). Therefore, the slip ratio λ cannot be determined from equation (2). On the other hand, the slip ratio λ during vehicle deceleration is defined by the following equation (1b). λ = (V - Rω) / V ... (1b) Therefore, while the vehicle is in motion, a torque in the deceleration direction is superimposed on the drive wheels for a short time by Tb, reducing the longitudinal force on the drive wheels by a change of ΔF, and the rotational speed of the drive wheels is set to ωb. At this time, as shown in Figure 2, the slip ratio λ decreases by a change of Δλb and changes to a slip ratio λb. This changed slip ratio λb is expressed by the following equation (3). λb=λ-Δλb=(V-Rωb) / V ···(3)

[0037] Here, assuming that the change in slip ratio due to the instantaneous torque command Ts is approximately the same in the acceleration and deceleration directions, and assuming Δλa ≈ Δλb, we can eliminate Δλa and Δλb from equations (2) and (3). Also, by rearranging equation (1), the vehicle's speed V can be expressed by the following equation (4). V=Rω(1-λ) ···(4)

[0038] By eliminating Δλa and Δλb from equations (2) and (3) and substituting the vehicle's moving speed V, expressed in equation (4), the slip ratio λ can be expressed as the solution to a quadratic equation in which the rotational speeds ω, ωa, and ωb of the drive wheels are obtained. Therefore, the road surface condition estimation unit 120 can determine the slip ratio λ using the rotational speeds ω, ωa, and ωb of the drive wheels. Alternatively, the road surface condition estimation unit 120 may determine the slip ratio λ by calculating the quadratic equation. Or, the road surface condition estimation unit 120 may store solutions to the quadratic equation relating to the slip ratio λ as map data in advance for various combinations of rotational speed values ​​ω, ωa, and ωb, and use this to determine the slip ratio λ.

[0039] In Figure 3, a period Tz is provided between the instantaneous torque command Ts for superimposing torque in the acceleration direction for a short period of Ta and the instantaneous torque command Ts for superimposing torque in the deceleration direction for a short period of Tb, during which the value of the instantaneous torque command Ts is set to 0. This period Tz is not necessarily required, but it is preferable to provide it between period Ta and period Tb. In this way, it is possible to check the change in the rotational speed ω of the drive wheels before and after superimposing torque in the acceleration and deceleration directions, respectively, which has the advantage of ensuring the reliability of the slip ratio λ estimation result by the road surface condition estimation unit 120.

[0040] Here, it is preferable that the time intervals Ta and Tb for superimposing instantaneous torque, and the time interval Tz between them, be shorter than the vehicle's response time to the torque change of the drive wheels, and longer than the torque setting time of the electric motor. For example, if the response time of the current controlling the torque of the electric motor is 1 ms, then Ta, Tb, and Tz can each be set to a range of 10 ms to 100 ms.

[0041] Furthermore, the road surface condition estimation unit 120 may estimate the friction coefficient μ of the road surface as the condition of the road surface in contact with the drive wheels. In this case, the estimated friction coefficient μ is input from the road surface condition estimation unit 120 to the torque command output unit 30 as road surface condition information I.

[0042] An example of the method for estimating the friction coefficient μ by the road surface condition estimation unit 120 is described below with reference to Figure 4. Figure 4 shows the relationship between the longitudinal force applied to the drive wheels and the slip ratio, with the friction coefficient μ as a parameter, under various road surface conditions. In Figure 4, as in Figure 2, the longitudinal force applied to the drive wheels in a moving vehicle is shown on the vertical axis, and the slip ratio is shown on the horizontal axis.

[0043] In Figure 4, curve 41 shows an example of the relationship between longitudinal force and slip ratio at a known friction coefficient μ0 on a dry road surface. Curves 42, 43, and 44 show examples of the relationship between longitudinal force and slip ratio at different road surface conditions (e.g., road surface under normal driving conditions, snow-covered road surface, icy road surface, etc.). As shown in these curves 41-44, the relationship between longitudinal force and slip ratio at road surfaces with different friction coefficients μ can be approximated as a similar shape to the road surface with friction coefficient μ0.

[0044] Therefore, in the vehicle control device 1 of this embodiment, for example, map data representing the relationship between longitudinal force and slip ratio on a road surface with a known coefficient of friction μ0, i.e., curve 41, is acquired in advance and stored in the road surface condition estimation unit 120. Then, the coefficient of friction μ on the current road surface is determined based on this map data and the slip ratio λ estimated by the estimation method described above. The relationship between longitudinal force and slip ratio on road surfaces with different coefficients of friction μ can be approximated as a similar form to the relationship between longitudinal force and slip ratio at a known coefficient of friction μ0, as shown in Figure 4. Therefore, the coefficient of friction μ on the current road surface can be determined using the estimated slip ratio λ on the current road surface.

[0045] Specifically, first, the gradient δ of the relationship between the longitudinal force and the slip ratio on the road surface where the vehicle is currently traveling is determined from the time change of the slip ratio λ estimated by the method described above. Then, the slip ratio λ0 at a gradient δ is determined in the map data of the friction coefficient μ0 that has been stored in advance. As described above, the relationship between the longitudinal force and the slip ratio on road surfaces with different friction coefficients μ can be approximated as a similar form. Therefore, the relationship between the slip ratio λ and friction coefficient μ on the current road surface and the slip ratio λ0 and friction coefficient μ0 represented by the map data can be expressed by the following equation (5). Thus, the friction coefficient μ on the current road surface can be determined from equation (5). λ:μ=λ0:μ0 ···(5)

[0046] The torque command output unit 30 adjusts the value of the torque command T so that the value of the friction coefficient μ is maximized on the current road surface, based on the estimated slip ratio λ or friction coefficient μ input as road surface condition information I from the road surface condition estimation unit 120. This enables stable vehicle control regardless of road surface conditions.

[0047] As explained above, the road surface condition estimation unit 120 can quickly and accurately estimate the slip ratio λ or friction coefficient μ of the road surface in contact with the drive wheels, based on the rotational speed ω of the drive wheels in response to the torque command T, and the rotational speeds ωa and ωb of the drive wheels when an instantaneous torque command Ts is superimposed on the torque command T. Here, it is generally known that when a vehicle is in motion, the friction coefficient μ and slip ratio λ are such that up to a predetermined slip ratio λp, the friction coefficient μ increases continuously as the value of the slip ratio λ increases, and beyond the slip ratio λp, the friction coefficient μ gradually decreases as the value of the slip ratio λ increases.

[0048] Figure 5 shows an example of the relationship between the friction coefficient μ and the slip ratio λ described above. In Figure 5, for each of the different road surface conditions (dry road surface, wet road surface, and icy road surface), examples of the relationship between the friction coefficient μ and the slip ratio λ when the slip ratio λ of the drive wheels changes in the positive and negative directions while the vehicle is running are shown.

[0049] When estimating the friction coefficient μ in the road surface condition estimation unit 120, the relationship between the friction coefficient μ and the slip ratio λ for each road surface condition, as shown in Figure 5, is acquired in advance as map data and stored in the road surface condition estimation unit 120. Then, the friction coefficient μ may be determined by referring to the map data from the estimated slip ratio λ value.

[0050] In Figure 5, the change in the coefficient of friction μ with increasing slip ratio λ is such that the absolute value of the coefficient of friction μ is maximum (μp). In the range of slip ratio λ where this state is obtained, i.e., 0 ≤ λ ≤ +λp, the vehicle is in a stable state. This range of slip ratio λ is referred to as the "stable region" below. On the other hand, when the value of the slip ratio λ is outside the stable region, the drive wheels slip or lock up occurs, and the vehicle is in an unstable state. This range of slip ratio λ is referred to as the "unstable region" below.

[0051] In the vehicle control device 1 of this embodiment, the road surface condition estimation unit 120 can determine the friction coefficient μ using the map data shown in Figure 5 when dealing with an unstable region. On the other hand, under normal circumstances, the drive wheels are controlled to maintain a stable region, so there is no problem in determining the friction coefficient μ using the aforementioned equation (5) without using the map data in Figure 5.

[0052] The road surface condition estimation method according to this embodiment, as described above, takes advantage of the fact that changes in vehicle conditions over a short period of time can be ignored. Therefore, the influence of factors such as vehicle weight and road surface gradient can be reduced in addition to the drive wheel speed V. However, when driving operations such as sharp turns or sudden braking are performed on the vehicle, it is necessary to appropriately control the vehicle's movement in accordance with the rapidly changing contact condition of the drive wheels. Such driving operations can be identified by the torque command output unit 30 based on the operation information Drv from the operation information output unit 10. Therefore, in such cases, by adjusting the torque command T by the torque command output unit 30 based on the friction coefficient μ estimated by the road surface condition estimation unit 120, the advantage of being able to appropriately respond even when the contact condition of the drive wheels changes over a short period of time can be obtained.

[0053] Furthermore, the road surface condition estimation unit 120 may pre-store as map data the relationship between the time change ΔT of the torque command T, or the change ΔF of the longitudinal force F applied to the drive wheels, and the change in slip ratio Δλ. This has the advantage of being able to estimate the slip ratio λ using only either the acceleration torque or the deceleration torque.

[0054] According to the road surface condition estimation method of the present invention, it is possible to estimate the road surface condition (slip ratio λ or friction coefficient μ) in contact with each drive wheel of a vehicle. Therefore, it has the advantage of enabling the detection of road surface conditions in various vehicle driving scenarios, thereby improving vehicle driving force control and driving safety.

[0055] According to the first embodiment of the present invention described above, the following effects are achieved.

[0056] (1) The vehicle control device 1 is a device for controlling a vehicle having one or more drive wheels. The vehicle control device 1 includes a torque command output unit 30 that outputs a torque command T for the braking and driving torque of the drive wheels, an instantaneous torque command output unit 110 that outputs an instantaneous torque command Ts for the instantaneous torque superimposed on the braking and driving torque, a drive control unit 130 that performs drive control of the drive wheels based on the torque command T and the instantaneous torque command Ts, and a road surface condition estimation unit 120 that estimates the condition of the road surface in contact with the drive wheels based on the rotational speed ω of the drive wheels when the instantaneous torque command output unit 110 outputs the instantaneous torque command Ts. In this way, the condition of the road surface in contact with each drive wheel of the vehicle can be accurately estimated.

[0057] (2) The instantaneous torque command output unit 110 outputs an instantaneous torque command Ts such that the instantaneous torque is superimposed on the braking and driving torque in a shorter time than the vehicle's response time to the torque change of the drive wheels. In this way, the road surface condition estimation unit 120 can estimate the road surface condition without adversely affecting the vehicle's behavior.

[0058] (3) The instantaneous torque command output unit 110 outputs an instantaneous torque command Ts such that an acceleration torque that increases the braking / driving torque in the vehicle's acceleration direction, or a deceleration torque that decreases the braking / driving torque in the vehicle's deceleration direction, is superimposed on the braking / driving torque as an instantaneous torque, as shown in Figure 3, for example. In this way, the rotational speed ωa of the drive wheels when acceleration torque is applied and the rotational speed ωb of the drive wheels when deceleration torque is applied can be obtained, and the slip ratio λ according to the road surface condition can be calculated using the estimation method described above.

[0059] (4) The vehicle control device 1 includes a requirement level specification unit 20 that specifies the required level for the road surface condition estimation performed by the road surface condition estimation unit 120. The instantaneous torque command output unit 110 changes the magnitude of the instantaneous torque command Ts based on the required level specified by the requirement level specification unit 20. In this way, the road surface condition estimation unit 120 can estimate the road surface condition with estimation accuracy appropriate to the situation.

[0060] (5) The requirement level designation unit 20 can determine the requirement level based on the driving operations performed by the driver. In this way, the requirement level can be appropriately determined according to the driving operations performed by the driver.

[0061] (6) The road surface condition estimation unit 120 estimates the slip ratio λ of the drive wheels or the friction coefficient μ of the road surface as the condition of the road surface in contact with the drive wheels. In this way, the road surface condition necessary for vehicle control can be appropriately estimated.

[0062] (Second embodiment) A second embodiment of the present invention will be described below. Figure 6 is a block diagram showing the configuration of a vehicle control device according to the second embodiment of the present invention.

[0063] The vehicle control device 1A shown in Figure 6 has the following differences compared to the vehicle control device 1 described in the first embodiment. Specifically, the vehicle control device 1A of this embodiment is used when mounted on a vehicle having multiple drive wheels, and has a drive wheel control unit 100 corresponding to each drive wheel. In Figure 6, each drive wheel control unit 100 of the vehicle control device 1A is represented as drive wheel control unit 100-1, 100-2, ... All of these drive wheel control units 100 have the same configuration as in Figure 1. Note that in Figure 6, only the configuration of drive wheel control unit 100-1 is shown, and the configurations of the other drive wheel control units 100-2, ... are not illustrated.

[0064] The number of drive wheel control units 100 in the vehicle control device 1A of this embodiment is determined according to the number of drive wheels of the vehicle. For example, if the vehicle is a two-wheel drive electric vehicle, the vehicle control device 1A is equipped with two drive wheel control units 100-1 and 100-2. If the vehicle is a four-wheel drive electric vehicle, the vehicle control device 1A is equipped with four drive wheel control units 100-1, 100-2, 100-3, and 100-4. In either case, each drive wheel control unit 100 has a similar configuration.

[0065] On the other hand, in the vehicle control device 1A of this embodiment, one operation information output unit 10, one request level specification unit 20, and one torque command output unit 30 are provided, regardless of the number of drive wheel control units 100. These are used in common among each drive wheel control unit 100.

[0066] Specifically, in the vehicle control device 1A of this embodiment, the request level specification unit 20 determines a request level corresponding to the condition of the road surface in contact with the drive wheel corresponding to the drive wheel 100, and outputs request signals S1, S2, ... to the instantaneous torque command output unit 110 of each drive wheel control unit 100. The request signals S1, S2, ... may be common to all units, or they may be different for each drive wheel control unit 100. The torque command output unit 30 adjusts the torque command for each drive wheel based on the road surface condition information I1, I2, ... output from the road surface condition estimation unit 120 of each drive wheel control unit 100. Then, it outputs the adjusted torque commands T1, T2, ... to the drive control unit 130 of each drive wheel control unit 100. This outputs braking and driving torque to each drive wheel according to the condition of the road surface in contact with each drive wheel, enabling the vehicle to run stably.

[0067] Figure 7 shows an example of a vehicle equipped with a vehicle control device according to a second embodiment of the present invention. The vehicle 2 shown in Figure 7 is an example of an in-wheel type electric vehicle and has four wheels 8. In Figure 7, the left front wheel of the vehicle 2 is denoted by reference numeral 8-1, the right front wheel by reference numeral 8-2, the left rear wheel by reference numeral 8-3, and the right rear wheel by reference numeral 8-4. An in-wheel type electric motor 3 and a wheel rotation sensor 4 are attached to each of these wheels 8, so that each wheel 8 operates as a drive wheel that can be independently driven and controlled. In Figure 7, the electric motor and wheel rotation sensor corresponding to the left front wheel 8-1 are denoted by reference numerals 3-1 and 4-1, the electric motor and wheel rotation sensor corresponding to the right front wheel 8-2 are denoted by reference numerals 3-2 and 4-2, the electric motor and wheel rotation sensor corresponding to the left rear wheel 8-3 are denoted by reference numerals 3-3 and 4-3, and the electric motor and wheel rotation sensor corresponding to the right rear wheel 8-4 are denoted by reference numerals 3-4 and 4-4.

[0068] Furthermore, when using an in-wheel type electric motor 3 as described above, the rotation angle sensor of the electric motor 3 may be used as the wheel rotation sensor 4. In this case, for example, a resolver, encoder, inductive sensor, or magnetic sensor can be used as the rotation angle sensor and wheel rotation sensor 4.

[0069] In this embodiment, it is preferable to reverse the phase of the instantaneous torques superimposed simultaneously on the four drive wheels 8 on the front and rear or left and right sides of the vehicle 2 by 180 degrees. Specifically, for example, acceleration torque is superimposed on the left front wheel 8-1 and the right front wheel 8-2 as instantaneous torques on the braking and driving torques represented by torque commands T1 and T2, and deceleration torque is superimposed on the left rear wheel 8-3 and the right rear wheel 8-4 as instantaneous torques on the braking and driving torques represented by torque commands T3 and T4, by adjusting the instantaneous torque commands Ts output from the instantaneous torque command output units 110 of the drive wheel control units 100-1 to 100-4. Furthermore, the instantaneous torque commands Ts output from the instantaneous torque command output units 110 of the drive wheel control units 100-1 to 100-4 are adjusted so that, for example, acceleration torque is superimposed on the left front wheel 8-1 and left rear wheel 8-3 as instantaneous torque to the braking and driving torques represented by torque commands T1 and T3, and deceleration torque is superimposed on the right front wheel 8-2 and right rear wheel 8-4 as instantaneous torque to the braking and driving torques represented by torque commands T2 and T4.

[0070] Alternatively, the phase of the instantaneous torque may be reversed by 180 degrees on both the front and rear and left and right sides of the vehicle 2. Specifically, for example, the instantaneous torque commands Ts output from the instantaneous torque command output units 110 of the drive wheel control units 100-1 to 100-4 are adjusted so that acceleration torque is superimposed on the left front wheel 8-1 and the right rear wheel 8-4 as instantaneous torque to the braking and driving torque represented by torque commands T1 and T4, and deceleration torque is superimposed on the right front wheel 8-2 and the left rear wheel 8-3 as instantaneous torque to the braking and driving torque represented by torque commands T2 and T3.

[0071] As explained above, by reversing the phase of the instantaneous torques superimposed simultaneously on either the front / rear or left / right sides of vehicle 2, or both, by 180 degrees, it is possible to cancel the instantaneous torque between the drive wheel superimposing the instantaneous torque in the acceleration direction and the drive wheel superimposing the instantaneous torque in the deceleration direction. As a result, there is an advantage in that the road surface condition in contact with the drive wheels can be estimated while the vehicle is running smoothly.

[0072] According to the second embodiment of the present invention described above, the vehicle 2 has a plurality of drive wheels that can be independently driven by the drive control units 130 of each drive wheel control unit 100 provided in the vehicle control device 1A. The instantaneous torque command output unit 110 of each drive wheel control unit 100 outputs an instantaneous torque command Ts such that acceleration torque is superimposed on the braking torque of the first drive wheel among the plurality of drive wheels, and deceleration torque is superimposed on the braking torque of the second drive wheel among the plurality of drive wheels. Here, the first drive wheel is one of the left and right wheels of the vehicle 2, or one of the front and rear wheels of the vehicle 2, and the second drive wheel is the other of the left and right wheels of the vehicle 2, or the other of the front and rear wheels of the vehicle. In this way, the road surface condition in contact with each drive wheel of the vehicle 2 can be accurately estimated while the vehicle 2 is running smoothly.

[0073] (Third embodiment) A third embodiment of the present invention will be described below. In this embodiment, a method will be described for improving the ride comfort of a vehicle and estimating the road surface condition at the same time as superimposing instantaneous torque on each drive wheel in a vehicle having multiple drive wheels, by canceling out the vibration of the vehicle caused by the superposition of instantaneous torque. The configuration of the vehicle control device in this embodiment may be either the vehicle control device 1 described in the first embodiment or the vehicle control device 1A described in the second embodiment.

[0074] Figure 8 shows an example of a vehicle vibration control method. In vehicles where each drive wheel can be controlled independently, a vibration control method is known that adjusts the jacking force that moves the vehicle vertically by controlling the braking and driving torque of each drive wheel, with the aim of reducing vehicle vibration. Specifically, for example, as shown in Figure 8(a), a torque in the deceleration direction is applied to the front wheels and a torque in the acceleration direction is applied to the rear wheels, thereby generating a downward jacking force and canceling out the upward vibration of the vehicle. Alternatively, for example, as shown in Figure 8(b), a torque in the acceleration direction is applied to the front wheels and a torque in the deceleration direction is applied to the rear wheels, thereby generating an upward jacking force and canceling out the downward vibration of the vehicle. By using such vibration control, it is possible to cancel out vehicle vibrations and improve ride comfort.

[0075] In the vibration damping control described above, it is necessary to constantly change the braking and driving torque of each drive wheel in order to cancel out vertical vibrations caused by unevenness in the road surface while the vehicle is in motion. By using this change in braking and driving torque as the instantaneous torque command Ts described above, it is possible to estimate the road surface condition in contact with each drive wheel in the same manner as described in the first and second embodiments. That is, in this embodiment, the instantaneous torque command output unit 110 outputs acceleration torque or deceleration torque as an instantaneous torque command Ts so that the jacking force generated in the vertical direction of the vehicle in response to the acceleration or deceleration of the vehicle acts in a direction that cancels out the vibration of the vehicle. This makes it possible to estimate the road surface condition while performing vibration damping control.

[0076] According to the third embodiment of the present invention described above, by treating the change in damping and driving torque in vibration damping control as an instantaneous torque command Ts, it is possible to estimate the road surface condition while performing vibration damping control. Therefore, there is an advantage in being able to achieve both ride comfort and safety for the vehicle.

[0077] In each of the above embodiments, it is preferable to use, for example, a permanent magnet synchronous motor (PMSM) as the electric motor that drives the drive wheels, but the effects of the present invention are not limited to this. Other electric motors, such as AC motors such as synchronous reluctance motors, wound-wound synchronous motors, and induction motors, or DC motors may also be used. Alternatively, the drive wheels may be driven using something other than an electric motor. As long as the torque of the drive wheels can be changed in a shorter time than the vehicle's response time in response to the instantaneous torque command Ts, it is possible to drive the drive wheels using any kind of device.

[0078] The present invention is not limited to the embodiments described above, and various modifications are included. For example, each of the embodiments described above is explained in detail to make the present invention easier to understand, and is not necessarily limited to having all of the described configurations. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations.

[0079] Furthermore, each of the above configurations, functions, processing units, processing means, etc., may be implemented in hardware, either partially or entirely, by designing them as integrated circuits, for example. Alternatively, each of the above configurations, functions, etc., may be implemented in software by having the processor interpret and execute programs that realize each of these functions.

[0080] Furthermore, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. [Explanation of Symbols]

[0081] 1,1A: Vehicle control device 2: Vehicles 3: Electric motor 4: Wheel rotation sensor 8: Wheels 10: Operation Information Output Unit 20: Request level specification section 30: Torque command output section 40: Motor drive unit 100: Drive wheel control unit 110: Instantaneous Torque Command Output Unit 120: Road surface condition estimation unit 130: Drive Control Unit

Claims

1. A vehicle control device for controlling a vehicle having one or more drive wheels, A torque command output unit that outputs a torque command for the braking and driving torque of the drive wheel, An instantaneous torque command output unit outputs an instantaneous torque command for the instantaneous torque superimposed on the braking drive torque, A drive control unit that controls the drive of the drive wheels based on the torque command and the instantaneous torque command, The system includes a road surface condition estimation unit that estimates the condition of the road surface in contact with the drive wheel based on the rotational speed of the drive wheel when the instantaneous torque command output unit outputs the instantaneous torque command, Vehicle control device.

2. In the vehicle control device according to claim 1, The instantaneous torque command output unit outputs the instantaneous torque command such that the instantaneous torque is superimposed on the braking and driving torque in a time shorter than the vehicle's response time to the torque change of the drive wheels. Vehicle control device.

3. In the vehicle control device according to claim 1, The instantaneous torque command output unit outputs the instantaneous torque command such that an acceleration torque that increases the braking / driving torque in the vehicle's acceleration direction, or a deceleration torque that decreases the braking / driving torque in the vehicle's deceleration direction, is superimposed on the braking / driving torque as the instantaneous torque. Vehicle control device.

4. In the vehicle control device according to claim 3, The vehicle has a plurality of drive wheels, each of which can be independently controlled by the drive control unit, The instantaneous torque command output unit outputs the instantaneous torque command such that the acceleration torque is superimposed on the braking torque for the first drive wheel among the plurality of drive wheels, and the deceleration torque is superimposed on the braking torque for the second drive wheel among the plurality of drive wheels. Vehicle control device.

5. In the vehicle control device according to claim 4, The first drive wheel is one of the left and right wheels of the vehicle, or one of the front and rear wheels of the vehicle. The second drive wheel is the other of the left and right wheels of the vehicle, or the other of the front and rear wheels of the vehicle. Vehicle control device.

6. In the vehicle control device according to claim 3, The instantaneous torque command output unit outputs the acceleration torque or deceleration torque as the instantaneous torque command such that the jacking force generated in the vertical direction of the vehicle in response to the acceleration or deceleration of the vehicle acts in a direction that cancels out the vibration of the vehicle. Vehicle control device.

7. In the vehicle control device according to claim 1, The system includes a requirement level specification unit that specifies the requirement level for the road surface condition estimation performed by the road surface condition estimation unit, The instantaneous torque command output unit changes the magnitude of the instantaneous torque command based on the required level specified by the required level specification unit. Vehicle control device.

8. In the vehicle control device according to claim 7, The aforementioned request level designation unit determines the request level based on the driving operations of the vehicle performed by the driver. Vehicle control device.

9. In the vehicle control device according to claim 1, The road surface condition estimation unit estimates the slip ratio of the drive wheels or the friction coefficient of the road surface as the road surface condition. Vehicle control device.

10. A vehicle control device according to any one of claims 1 to 9, A vehicle comprising one or more drive wheels that are driven and controlled by the vehicle control device.

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