阅读说明：本技术 环保车辆及控制环保车辆的电机转矩的方法 (Eco-friendly vehicle and method of controlling motor torque of eco-friendly vehicle ) 是由 张苏摞 金贵哲 于 2020-04-29 设计创作，主要内容包括：一种环保车辆及控制环保车辆的电机转矩的方法,该环保车辆包括电机,并且通过在控制环保车辆的启动时根据车轮行为特性确定路面特性,以及根据道路特性确定结果,在车辆起步时,在发生明显的车轮打滑之前控制电动的机转矩来控制该环保车辆的电机转矩。控制环保车辆的电机转矩的方法包括确定车辆的车轮行为特性,基于车辆的车轮行为特性确定车辆所在道路的路面特性,以及基于该路面特性控制车辆的电机转矩。(An eco-vehicle and a method of controlling motor torque of the eco-vehicle, the eco-vehicle including a motor and controlling the motor torque of the eco-vehicle by determining road surface characteristics according to wheel behavior characteristics when controlling start of the eco-vehicle and controlling electric motor torque before occurrence of significant wheel slip at vehicle start-up according to the road characteristic determination result. The method of controlling motor torque of an environmentally friendly vehicle includes determining a wheel behavior characteristic of the vehicle, determining a road surface characteristic of a road on which the vehicle is located based on the wheel behavior characteristic of the vehicle, and controlling motor torque of the vehicle based on the road surface characteristic.)

1. A method of controlling motor torque of an environmentally friendly vehicle, the method comprising the steps of:

determining a wheel behavior characteristic of the vehicle;

determining road surface characteristics of a road on which the vehicle is located based on the wheel behavior characteristics of the vehicle; and

controlling a motor torque of the vehicle based on the road surface characteristic.

2. The method of claim 1, wherein determining the wheel behavior characteristic comprises:

determining the wheel behavior characteristic of the vehicle using a wheel acceleration rate, a wheel speed, and a motor torque of the vehicle.

3. The method of claim 2, wherein determining the road surface characteristic comprises:

when the wheel acceleration rate W of the vehicle_jerkAnd motor torque T_motorSatisfies the respective preset reference ranges and the wheel acceleration W_decelAnd a wheel acceleration code count value Cnt_wdecelAnd determining the road surface characteristics as a low-friction road surface when the preset reference ranges are met.

4. The method of claim 3, wherein determining the road surface characteristic comprises:

when the wheel acceleration rate W of the vehicle_jerkAnd the motor torque T_motorNot satisfying the respective preset reference ranges or the wheel acceleration W_decelAnd the wheel acceleration code count value Cnt_wdecelAnd when the preset reference ranges are not met, determining the road surface characteristics as a high-friction road surface.

5. The method of claim 4, further comprising:

calculating the wheel acceleration W based on a rate of change of wheel speeds of left and right drive wheels of the vehicle_decelOr the wheel acceleration rate W_jerk。

6. The method of claim 5, wherein the wheel acceleration is calculated as in equation 1 below:

wherein, in equation 1, W_decelIs the wheel acceleration, and WSPD_LHAnd WSPD_RHIs the wheel speed of the left and right drive wheels.

7. The method of claim 5, wherein the wheel acceleration rate is calculated as in equation 2 below:

wherein, in equation 2, W_jerkIs the wheel acceleration rate, and WSPD_LHAnd WSPD_RHIs the wheel speed of the left and right drive wheels.

8. The method of claim 1, wherein controlling the motor torque comprises:

controlling the motor torque to reduce wheel slip of the vehicle when the determined road surface characteristic is a low friction road surface.

9. The method of claim 1, further comprising:

displaying the result of determining the road surface characteristic on a display.

10. The method of claim 9, wherein the displaying comprises:

when the determination result of the road surface characteristic is a low friction road surface, displaying on the display that the current road surface is the low friction road surface.

11. An environmentally friendly vehicle comprising:

a motor configured to generate power for driving a vehicle; and

a controller configured to determine a wheel behavior characteristic of the vehicle,

determining road surface characteristics of a road on which the vehicle is located based on wheel behavior characteristics of the vehicle, an

Controlling a motor torque of the vehicle based on the road surface characteristic.

12. The environmentally friendly vehicle of claim 11, wherein the controller is configured to use a wheel acceleration rate W of the vehicle_jerkWheel speed and motor torque T_motorDetermining the wheel behavior characteristic of the vehicle.

13. The eco-friendly vehicle as claimed in claim 12, wherein a wheel acceleration rate W of the vehicle is measured_jerkAnd motor torque T_motorSatisfies the respective preset reference ranges and the wheel acceleration W_decelAnd a wheel acceleration code count value Cnt_wdecelThe controller is configured to determine the road surface characteristic as a low-friction road surface when each preset reference range is satisfied.

14. The eco-vehicle of claim 13, wherein the wheel acceleration rate W of the vehicle is when_jerkAnd the motor torque T_motorNot satisfying the respective preset reference ranges or the wheel acceleration W_decelAnd the wheel acceleration code count value Cnt_wdecelThe controller is configured to determine the road surface characteristic as a high-friction road surface when the preset reference ranges are not satisfied.

15. The environmentally friendly vehicle of claim 14, wherein the controller is configured to calculate the wheel acceleration WoUc based on a rate of change of wheel speeds of left and right drive wheels of the vehicle_decelOr the vehicleAcceleration rate W of wheel_jerk。

16. The environmentally friendly vehicle of claim 15, wherein the controller is configured to calculate the wheel acceleration as in equation 1 below:

wherein, in equation 1, W_decelIs the wheel acceleration, and WSPD_LHAnd WSPD_RHIs the wheel speed of the left and right drive wheels.

17. The environmentally friendly vehicle of claim 15, wherein the controller is configured to calculate the wheel acceleration rate as in equation 2 below:

wherein, in equation 2, W_jerkIs the wheel acceleration rate, and WSPD_LHAnd WSPD_RHIs the wheel speed of the left and right drive wheels.

18. The environmentally friendly vehicle of claim 11, wherein when the determined road surface characteristic is a low friction road surface, the controller is configured to control the motor torque to reduce wheel slip of the vehicle.

19. The environmentally friendly vehicle of claim 11, wherein the controller is configured to display a result of determining the road surface characteristic on a display.

20. The eco-vehicle of claim 19, wherein when the determination result of the road surface property is a low friction road surface, the controller is configured to display on the display that the current road surface is the low friction road surface.

Technical Field

The present disclosure relates to a vehicle, and more particularly, to a vehicle having a motor as a power source to generate driving force of wheels.

Background

In an environmentally-friendly vehicle having an electric motor (i.e., an electric motor) as a power source for generating driving force of wheels, the electric motor responds faster than an engine (i.e., an internal combustion engine). The eco-friendly vehicle can generate high torque and thus is excellent in instantaneous acceleration performance. In addition, in the case of an electric vehicle, a tire having a very small frictional force is used to increase the fully charged one-time travelable distance, and in this case, the frictional force (grip) of the tire is reduced.

The environmentally-friendly vehicle equipped with the motor generates rapid and large wheel slip of the drive wheel on a low-friction road surface, which may result in poor starting stability of the vehicle. Currently, when wheel slip of the drive wheels occurs more than a predetermined amount, control is applied to reduce the motor torque. However, since wheel slip occurs rapidly and to a large extent due to the characteristics of the eco-friendly vehicle having the motor, there is a problem in that the wheel slip cannot be sufficiently reduced even when the motor torque is controlled.

Disclosure of Invention

Therefore, it is an aspect of the present disclosure to determine a road surface characteristic based on a wheel behavior characteristic when controlling a start of an eco-vehicle equipped with a motor. Another aspect of the present disclosure is to control the torque of the motor before significant slip of the wheels occurs at the time of vehicle start, based on the road characteristic determination result.

Additional aspects of the disclosure are set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the disclosure.

According to an aspect of the present disclosure, a method of controlling a motor torque of an eco-friendly vehicle includes: determining a wheel behavior characteristic of the vehicle; determining road surface characteristics of a road on which the vehicle is located based on wheel behavior characteristics of the vehicle; the motor torque of the vehicle is controlled according to the road surface characteristics.

The determination of the wheel behavior characteristic of the vehicle may comprise: the wheel behavior characteristics of the vehicle are determined using the wheel acceleration rate, the wheel speed, and the motor torque of the vehicle.

The determination of the road surface property of the road may comprise: acceleration rate W of vehicle wheel_jerkAnd motor torque T_motorSatisfy each preset reference range and the wheel acceleration W_decelAnd a wheel acceleration code count value Cnt_wdecelAnd when the preset reference ranges are met, determining the road surface characteristics as the low-friction road surface.

The determination of the road surface property of the road may comprise: vehicle for carrying as requiredAcceleration rate W of vehicle wheel_jerkAnd motor torque T_motorWhen the preset reference ranges are not satisfied, and when the wheel acceleration W_decelAnd a wheel acceleration code count value Cnt_wdecelAnd when the preset reference ranges are not met, determining the road surface characteristics as a high-friction road surface.

The method may further include calculating a wheel acceleration or a wheel acceleration rate based on a rate of change of wheel speed of left and right drive wheels of the vehicle.

The wheel acceleration can be calculated as the following equation 1.

In equation 1, W_decelIs wheel acceleration, WSPD_LHAnd WSPD_RHIs the wheel speed of the left and right drive wheels.

The wheel acceleration rate can be calculated as the following equation 2.

In equation 2, W_jerkIs the wheel acceleration rate, WSPD_LHAnd WSPD_RHIs the wheel speed of the left and right drive wheels.

The control of the motor torque of the vehicle may include: when the determined road surface characteristic is a low friction road surface, the motor torque is controlled to reduce wheel slip of the vehicle.

The method may further include displaying the results of determining the road surface characteristic on a display.

The displaying may include: when the determination result of the road surface characteristic is a low-friction road surface, it is displayed on the display that the current road surface is the low-friction road surface.

According to another aspect of the present disclosure, an eco-vehicle includes a motor configured to generate power for driving the vehicle and a controller. The controller is configured to: determining a wheel behavior characteristic of the vehicle; determining road surface characteristics of a road on which the vehicle is located based on wheel behavior characteristics of the vehicle; and controlling motor torque of the vehicle based on the road surface characteristic.

The controller may be configured to determine a wheel behavior characteristic of the vehicle using a wheel acceleration rate, a wheel speed, and a motor torque of the vehicle.

Acceleration rate W of vehicle wheel_jerkAnd motor torque T_motorSatisfy each preset reference range and the wheel acceleration W_decelAnd a wheel acceleration code count value Cnt_wdecelThe controller may be configured to determine the road surface characteristic as the low-friction road surface when the preset reference ranges are satisfied.

Acceleration rate W of vehicle wheel_jerkAnd motor torque T_motorNot satisfying the preset reference ranges and the wheel acceleration W_decelAnd a wheel acceleration code count value Cnt_wdecelWhen the preset reference ranges are not satisfied, the controller may be configured to determine the road surface characteristic as a high-friction road surface.

The controller may be configured to calculate a wheel acceleration or a wheel acceleration rate based on a rate of change of wheel speed of left and right drive wheels of the vehicle.

The controller may be configured to calculate the wheel acceleration as the following equation 1.

In equation 1, W_decelIs wheel acceleration, and WSPD_LHAnd WSPD_RHIs the wheel speed of the left and right drive wheels.

The controller may be configured to calculate the wheel acceleration rate as the following equation 2.

In equation 2, W_jerkIs the wheel acceleration rate, and WSPD_LHAnd WSPD_RHIs a left driving wheel and a right driving wheelThe wheel speed of the wheel.

When the determined road surface characteristic is a low friction road surface, the controller may be configured to control the motor torque to reduce wheel slip of the vehicle.

The controller may be configured to display a result of determining the road surface characteristic on the display.

The controller may be configured to display the current road surface as a low-friction road surface on the display when the determination result of the road surface characteristic is the low-friction road surface.

Drawings

These and/or other aspects of the present disclosure will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a view showing a control system of a vehicle according to an embodiment of the present disclosure.

Fig. 2 is a view illustrating a method of controlling motor torque of a vehicle according to an embodiment of the present disclosure.

Fig. 3 is a view illustrating a method of determining whether to use past motor torque control data in a method of controlling motor torque of a vehicle according to an embodiment of the present disclosure.

Fig. 4 is a view showing wheel behavior characteristic determination and road surface characteristic determination in a method of controlling motor torque of a vehicle according to an embodiment of the present disclosure.

Fig. 5A and 5B are views showing a road surface characteristic determination reference in motor torque control of a vehicle according to an embodiment of the present disclosure.

Fig. 6 is a diagram illustrating various aspects of a method of controlling motor torque of a vehicle according to an embodiment of the present disclosure.

Detailed Description

Fig. 1 is a view showing a control system of a vehicle according to an embodiment of the present disclosure.

A controller 102 may be provided to control the overall operation of the vehicle. In particular, the controller 102 of the vehicle may determine a current road surface state to generate a road surface determination result. The controller 102 may control the torque of the motor 150 according to the generated road surface determination result so that no wheel slip occurs (or at least the wheel slip is minimized) when the vehicle is started, to ensure the running stability of the vehicle. The controller 102 may be any one of a plurality of electronic control units provided in a vehicle.

The controller 102 may internally include wheel behavior determination logic 104 and road surface determination logic 106. The road surface condition may refer to a friction coefficient of the road surface. The higher the friction coefficient of the road surface, the greater the friction between the wheel and the road surface, and therefore no or reduced wheel slip occurs. Conversely, the lower the friction coefficient of the road surface, the smaller the friction force between the wheel and the road surface, so that the wheel slip increases.

The wheel behavior determination logic 104 may collect information related to wheel behavior and determine wheel behavior based on the collected information. The information related to wheel behavior may include wheel speed, wheel acceleration and wheel acceleration rate. The road surface determination logic 106 may determine the state of the road surface based on the wheel behavior determination results of the wheel behavior determination logic 104.

The wheel acceleration rate may refer to the sudden movement of the wheels in the fore and aft direction when the vehicle is taking off (taking off). The amount of change in wheel acceleration per unit time (i.e., the derivative of wheel acceleration) may be used to estimate the magnitude (degrees) of the wheel acceleration rate (wheel jerk). The wheel acceleration can be obtained by differentiating the wheel speed. Distinguishing the wheel acceleration makes it possible to obtain a value of the wheel acceleration rate.

For this reason, the controller 102 may determine or obtain a wheel acceleration, a wheel acceleration rate, a wheel slip, a motor torque control value, a vehicle speed, a vehicle deceleration, a road surface state, and the like using various information input from the outside.

The wheel behavior determination logic 104 of the controller 102 may use various information received from the outside to perform the following operations.

Wheel acceleration calculation and wheel acceleration sign verification:

in equation 1, W_decelIs wheel acceleration, and WSPD_LHAnd WSPD_RHIs the wheel speed of the left and right drive wheels.

Wheel acceleration rate:

in equation 2, W_jerkIs the wheel acceleration rate, and WSPD_LHAnd WSPD_RHIs the wheel speed of the left and right drive wheels.

Wheel slip:

W_spin＝v_whi-v_vehicle <equation 3>

In equation 3, v_whlIs the wheel speed of the non-driven wheel, and v_vehicleIs the vehicle speed.

Vehicle speed and deceleration:

in equation 4, v_vehicleIs the vehicle speed, v_decelIs the vehicle deceleration.

A Control Area Network (CAN) signal receiver 122 may receive various signals (information) transmitted through a CAN provided in the vehicle and transmit them to the controller 102.

The navigation 124 may provide the current position of the vehicle to the controller 102. The controller 102 may recall the past road surface determination result of the position where the vehicle is currently located from the memory 170, which will be described, based on the information of the current position of the vehicle provided from the navigation 124. The controller 102 may utilize torque control of the motor 150 according to the road surface state.

When the vehicle is stopped on a slope and then started, hill start assist control (HAC)126 may prevent the vehicle from backing up by temporarily operating the brake. Controller 102 may receive control information for preventing ramp roll by communicating with HAC126 via CAN. The controller 102 can distinguish whether the slope of where the vehicle is currently located is slow or fast by control information provided from the HAC 126.

A temperature detector 132 may be provided to detect an outdoor temperature around the vehicle. Information regarding the outdoor temperature detected by the temperature detector 132 may be provided to the controller 102. In the above description of the navigation 124, the controller 102 may extract the past road surface determination result of the current position of the vehicle from the memory to utilize the torque control of the motor 150 according to the road surface state. At this time, when the outdoor temperature is 0 ℃ or more, the controller 102 may utilize the past road surface state information (see 206 in fig. 2). In contrast, when the outdoor temperature is less than 0 ℃, the controller 102 may perform torque control of another aspect without using the past road surface state information (see 218 in fig. 2). The controller 102 may perform the motor torque control by referring to the temperature of the drive system of the vehicle and the outdoor temperature.

A wheel speed detector 134 may be provided to detect the rotational speed of the wheels of the vehicle. The wheel speed detected by the wheel speed detector 134 may be provided to the controller 102. The controller 102 may calculate a wheel acceleration and a wheel acceleration rate based on the wheel speed information provided from the wheel speed detector 134. The controller 102 obtains the wheel behavior characteristics of the vehicle from the information of the wheel speed, the wheel acceleration, and the wheel acceleration rate.

A vehicle speed detector 136 may be provided to detect the traveling speed of the vehicle. The vehicle speed information detected by the vehicle speed detector 136 may be provided to the controller 102. The controller 102 may be based on the wheel speed v_whlWith vehicle speed v_vehicleThe difference therebetween to calculate the wheel slip W_spin。

The motor 150 is a power source for driving the vehicle. The vehicle may be an electric vehicle driven only by the power of the motor 150, or a hybrid vehicle using the power of the motor 150 and an engine (not shown).

The dashboard 160 is a display that displays various traveling information of the vehicle. In particular, the dashboard 160 of the vehicle may display the road surface determination result. The passenger of the vehicle can recognize the road surface state of the road on which the vehicle is currently traveling from the road surface determination result displayed in the instrument panel 160.

The memory 170 is a memory that stores various information and data generated in the vehicle. In particular, the memory 170 of the vehicle may store the road surface determination results for each position or orientation. When a new road surface determination result occurs at the same position, the controller 102 may update the existing road surface determination result for the position stored in the memory 170 with the new road surface determination result.

Fig. 2 is a view illustrating a method of controlling motor torque of a vehicle according to an embodiment of the present disclosure. In the method of controlling the motor torque of the vehicle shown in fig. 2, the road surface characteristics of the place where the vehicle is located are determined by the wheel behavior characteristics of the vehicle. The motor torque of the vehicle is controlled in accordance with the determined road surface characteristic.

First, the controller 102 may receive various signals (information) transmitted through the CAN of the vehicle through the CAN signal receiver 122 (202). For example, the controller 102 may obtain control information for the HAC and torque information for the motor 150 from the CAN signal. The controller 102 may distinguish whether the slope where the vehicle is currently located is slow or fast based on the control information provided by the HAC 126. The torque information of the motor 150 may be used to control the motor 150 such that the current torque of the motor 150 follows the target torque.

Controller 102 may also determine whether to utilize past motor torque control data stored in memory 170 (204). When the past road surface determination data at the current position is stored in the memory 170, the controller 102 may determine whether to use the past road surface determination data stored in the memory 170 or to attempt a new road surface determination.

This is described with reference to fig. 3. Fig. 3 is a view illustrating a method of determining whether to use past motor torque control data (204) in a method of controlling motor torque of a vehicle according to an embodiment of the present disclosure.

To this end, the controller 102 may identify whether data of road surface determinations that have been made in the past at the current position or orientation of the vehicle is stored in the memory 170 (302).

When the history of low-friction road surfaces at the current position of the vehicle in the past has been stored in the memory 170 ("yes" in 304), the controller 102 may recognize that the temperature outside the current vehicle, i.e., the outdoor temperature, is lower than 0 ℃ (304). When the outdoor temperature is lower than 0 ℃, that is, when the current position is historically determined to be a low-friction road surface (yes in 304) and the current outdoor temperature is lower than 0 ℃ (yes in 306), the controller 102 may determine that the road surface of the current position is a low-friction road surface, and may perform motor torque control (see low-friction road surface control step 2 (see 218 in fig. 2)) to cause the vehicle to start stably on the low-friction road surface. In contrast, when there is no history of the low friction road in the past (no in 304), or when there is a history of the low friction road in the past and the current outdoor temperature is higher than 0 ℃ (no in 306), the controller 102 may determine that the road surface state information needs to be updated and attempt to determine new road surface characteristics (see 206 and 208 in fig. 2).

Returning to fig. 2, when it is determined that a new road surface property determination is required (no in 204), the controller 102 may perform the wheel behavior property determination as a preliminary operation of the road surface property determination (206). The behavior characteristics of the wheels of the vehicle differ according to the road surface state. The wheel behavior characteristics may include, for example, wheel acceleration and wheel acceleration rate. In other words, since the wheel acceleration and the wheel acceleration rate are different on the low-friction road surface and the high-friction road surface, the controller 102 may determine the road surface characteristics by the wheel behavior characteristics such as the wheel acceleration and the wheel acceleration rate.

Further, the controller 102 may determine a road surface characteristic on which the vehicle is currently located according to the wheel behavior characteristic determination result (208).

Determination of the road surface characteristic based on the wheel behavior characteristic determination is described with reference to fig. 4, 5A, and 5B. Fig. 4 is a view showing a wheel behavior characteristic determination (206) and a road surface characteristic determination (208) in a method of controlling motor torque of a vehicle according to an embodiment of the present disclosure. Fig. 5A and 5B are views showing a road surface characteristic determination reference in motor torque control of a vehicle according to an embodiment of the present disclosure.

The various aspects of the pavement shown in fig. 4, 5A, and 5B may be defined as follows, respectively.

Dry pavement is a general road surface that is not wet. Wet pavement refers to a road with a wet surface. In embodiments of the present disclosure, dry pavement and wet pavement may be classified as high friction pavement. On high friction roads, the friction between the wheels and the road is large enough that no special motor torque control is required at vehicle start-up.

A slope may refer to a road that is uneven and sloped. The detection of the slope or the detection of the steepness may be detected by the operation of the HAC126 of the vehicle or by an acceleration sensor provided in the vehicle.

The special road surface can be deceleration strip, manhole cover, gravel field, belgium road surface, etc. Belgian pavement is a bumpy road made of small bricks, and is also called Belgian road. In the embodiment of the invention, the special road surface is also classified as a high friction road surface. In other words, all road surfaces except for the low-friction road surface can be classified as the high-friction road surface.

A snow road or an ice road may be a road surface on which snow or water freezes due to low outdoor temperature. In the embodiments of the present disclosure, a snow road or an icy road may be classified as a low friction road surface. In a snowy road or an icy road, the frictional force between the wheels and the road surface is significantly reduced, and thus special motor torque control is required at the time of starting the vehicle.

As shown in fig. 4, the controller 102 may obtain data required for the wheel behavior characteristic determination to determine the wheel behavior characteristic determination (462). The data required for the determination of the wheel behavior characteristics may include CAN signals and position or orientation information, slope anti-roll control information, outdoor temperature, wheel speed, vehicle speed, motor torque, data stored in the memory 170, and the like.

First, the controller 102 may identify the wheel acceleration rate W_jerkAnd motor torque T_motorWhether each preset reference range is satisfied (464). In other words, when the wheel acceleration rate W_jerkExceeds the reference value alpha of the acceleration rate of the wheel and the motor torque T_motorWhen the torque is smaller than the motor torque reference value beta, controlThe machine 102 may determine a wheel acceleration rate W_jerkAnd motor torque T_motorEach preset reference range is satisfied (see fig. 5A).

The wheel acceleration rate reference value α may be determined by detecting the wheel acceleration rate on each road surface through an experiment of starting the vehicle on various road surfaces. For example, as shown in fig. 5A, the value "α" may be set to distinguish between the wheel acceleration rate values on roads including dry roads, wet roads, and slopes and the wheel acceleration rate values on roads including special roads, snowy roads, and icy roads. The value α may be set as the wheel acceleration rate reference value α.

The motor torque reference value "β" may also be determined by detecting the torque value of the motor 150 on each road side through experiments in which the vehicle is started on various road surfaces. For example, as shown in fig. 5A, a value "β" may be set to distinguish a motor torque on a road including a dry road, a wet road, and a slope from a motor torque on a road including a special road, a snowy road, and an icy road. The value β may be set as the motor torque reference value β.

Therefore, the wheel acceleration rate W when at the current position of the vehicle_jerkWhen the wheel acceleration rate reference value α is exceeded, this means that the current road surface may be a snow road, an ice road, or a special road surface. In addition, when at the current position of the vehicle, the motor torque T_motorSmaller than the motor torque reference value beta, this means that the current road surface may be a snow covered road, an ice covered road or a special road surface. When at the current position of the vehicle, the wheel acceleration rate W_jerkExceeds the reference value alpha of the acceleration rate of the wheel, and the motor torque T_motorLess than the motor torque reference value beta, this means that the current road surface is likely to be a snow covered road, an icy road or a special road surface.

When acceleration rate W of wheel_jerkAnd motor torque T_motorWhen the preset reference ranges are satisfied (yes in 464), the controller 102 may recognize the wheel acceleration W_decelAnd a wheel acceleration code count value Cnt_wdecelWhether each preset reference range is satisfied (466). The wheel acceleration code may be referred to by the symbol (+) (0) (-)Showing the direction of the change in wheel acceleration. The amount of change in the wheel speed per unit time, that is, the wheel acceleration becomes large when the wheel acceleration is positive, and the wheel acceleration becomes small when the wheel acceleration is negative. When the symbol is (0), the wheel acceleration is kept as it is. The wheel acceleration code count value Cntwdecel may be a value obtained by counting and accumulating wheel acceleration codes at predetermined intervals.

When the wheel acceleration W_decelExceeds the wheel acceleration reference value 'gamma' and counts the wheel acceleration code values Cnt_wdecelThe controller 102 may determine the wheel acceleration W when it is less than the wheel acceleration code count reference value' theta_decelAnd a wheel acceleration code count value Cnt_wdecelEach preset reference range is satisfied (see fig. 5B).

The wheel acceleration reference value γ can be determined by detecting the wheel acceleration on each road surface through an experiment of starting the vehicle on various road surfaces. For example, as shown in fig. 5B, the value γ may be set to distinguish between the acceleration of the wheels on a road including a special road surface and a dry road surface and the acceleration of the wheels on a road including a wet road, a special road surface, a snow road, and an icy road. The value γ may be set as the wheel acceleration reference value γ.

Wheel acceleration code count reference Cnt_wdecelIt can also be determined by detecting the wheel acceleration code on each road surface through experiments to start the vehicle on various road surfaces. For example, as shown in fig. 5B, the value θ may be set to distinguish the wheel acceleration code count value on a road including a special road surface, a dry road surface, and a wet road surface from the wheel acceleration code count value on a road including a snow road and an icy road. The value θ may be set as the wheel acceleration code count reference value θ.

Therefore, when the wheel acceleration W_decelWhen the vehicle wheel acceleration reference value gamma is exceeded, the current road surface can be a wet road surface, a special road surface, a snow covered road or an icy road. In addition, the reference value Cnt is counted when the wheel acceleration code is applied_wdecelWhen smaller than the wheel acceleration code count reference value θ, it means that the current road surface may be a snowy road or an icy road.When the wheel acceleration W_decelExceeding the wheel acceleration reference value gamma and the wheel acceleration code counting reference value Cnt_wdecelWhen smaller than the wheel acceleration code count reference value θ, it means that the current road surface is likely to be a snow road, an icy road, or a special road surface.

In operation 466 of FIG. 4, when the wheel acceleration W is_decelAnd a wheel acceleration code count value Cnt_wdecelWhen the preset reference ranges are satisfied (yes in 466), the controller 102 may determine the current road surface as the low friction road surface (482). On the contrary, when the wheel acceleration W is_decelAnd a wheel acceleration code count value Cnt_wdecelWhen the preset reference ranges are not satisfied (no in 466), the controller 102 may determine the current road surface as the special road surface (484).

Returning to 464 of FIG. 4, when the wheel acceleration rate W_jerkAnd motor torque T_motorWhen the preset reference ranges are not satisfied (no in 464), the controller 102 may recognize whether the slope anti-roll operation is performed by communicating with the HAC126 or may determine whether the current road surface is a slope (468).

When HAC126 is operating or the road surface is determined to be a slope ("yes" in 468), controller 102 may determine that the road surface is a slope (uphill). Since the HAC126 runs on an uphill road, the controller 102 may recognize that the current road surface is a hill through the operation of the HAC 126. Conversely, when HAC126 is not operating or the road surface is determined not to be a hill ("no" at 468), controller 102 may determine the road surface to be a high friction road surface (488). In other words, when the current road surface is not a low friction road surface and is not a slope, the controller 102 may determine the road surface as a high friction road surface.

As shown in fig. 5A and 5B, according to the wheel acceleration rate W_jerkTorque of motor T_motorAcceleration W of wheel_decelAnd a wheel acceleration code count value Cnt_wdecelThe road surface may be classified into "dry road surface", "wet road surface", "slope", "special road surface", "snow-covered road", "ice road".

In fig. 5A and 5B, the snow road and the ice road are low-friction road surfaces. The low-friction road surface may be defined as a low-friction road surface at a level at which a friction force required for stable start of the vehicle is not obtained.

The reference for determining the road surface characteristic as the low-friction road surface may be variously applied depending on the vehicle. In other words, the frictional force required for stable start of the vehicle varies depending on the load of the vehicle and the state of the tires. Therefore, it is desirable to determine reference values (α, β, γ, θ, etc. in fig. 4) for distinguishing or identifying "low friction roads" requiring motor torque control by experimentally obtaining and analyzing data on various road surfaces.

Returning to fig. 2, when it is determined that the current road surface is a low-friction road surface (yes in 210), controller 102 may execute low-friction road surface motor torque control step 1 (212). When the past motor torque control data is used in the above-described operation 204 (yes in 204), the controller 102 may execute the low-friction-road-surface motor torque control step 2 (218).

The low-friction road surface motor torque control step 1 (see 212 in fig. 2) and the low-friction road surface motor torque control step 2 (see 218 in fig. 2) are described below with reference to fig. 6.

Fig. 6 is a diagram illustrating various aspects of a method of controlling motor torque of a vehicle according to an embodiment of the present disclosure. Fig. 2 described above shows two cases 212 and 218 of motor torque control of the vehicle on a low-friction road surface. In other words, when no in 204 determines the new road surface characteristic without using the past motor torque control data, the controller 102 may execute low-friction road surface motor torque control step 1 (see 212 in fig. 2).

In contrast, when the new road surface characteristics are determined using the past motor torque control data (yes in 204), the controller 102 may execute the low-friction road surface motor torque control step 2 (see 218 in fig. 2). In fig. 6, the characteristics of low-friction road surface motor torque control step 1(212) and low-friction road surface motor torque control step 2(218), which are two aspects of the method of controlling the vehicle motor torque, and the characteristics of the basic control for identifying the relative difference are shown.

As shown in fig. 6, the basic control (broken line diagram) increases the motor torque as the operation amount of the accelerator pedal increases, without considering the road characteristics. Then, when the motor torque reaches a predetermined value, the basic control slowly changes the rate of change (inclination) of the motor torque. The motor torque control aspect is a control aspect that regards the oscillation performance of the vehicle as a primary task.

Based on the determination result of the road surface characteristic, the low-friction road surface motor torque control step 1 (solid line diagram) is for controlling the torque of the motor 150 by determining the wheel behavior characteristic of the current vehicle without using the motor torque control data in the past. As shown in fig. 6, low-friction-road-surface motor torque control step 1 reduces the maximum value of the motor torque as compared with the case of the basic control (dashed line). In other words, the controller 102 also increases the motor torque as the operation amount of the accelerator pedal increases, while maintaining the motor torque at a position where the motor torque is relatively small with respect to the basic control (dashed line diagram). The motor torque is then reduced to a smaller value and the motor torque in the reduced state is maintained. This is to stably start the vehicle by reducing the motor torque below a predetermined value at which no wheel slip is generated. This is because the motor torque is too high on a low-friction road surface, resulting in wheel slip and unstable vehicle launch.

Low friction road surface motor torque control step 2 (two dashed lines) utilizes the past motor torque control data, but controls the torque of the motor 150 when the current temperature is below 0 ℃. As shown in fig. 6, in the low-friction-road-surface motor torque control step 2, the rate of change (inclination) and the maximum value of the motor torque are relatively smaller than those in the basic control (dashed line diagram) and the low-friction-road-surface motor torque control step 1 (solid line diagram). In other words, the controller 102 increases the motor torque as the operation amount of the accelerator pedal increases, while maintaining the motor torque at a position (broken line diagram) relatively smaller than that in the case of the basic control. However, in the low-friction-road-surface motor torque control step 2, the rate of change in the motor torque is relatively smaller than in the basic control (dashed line diagram) or the low-friction-road-surface motor torque control step 1 (solid line diagram). This is because the temperature is low even on a low-friction road surface, so that the rate of change in the motor torque is further reduced, and the vehicle can be started more stably.

Returning to fig. 2, when it is determined that the current road surface is not the low friction road surface ("no" at 210), the controller 102 may determine that the current road surface characteristic is at least one of a high friction road surface, a special road surface, and a slope. Therefore, the motor torque can be controlled in the basic control (broken line diagram) mentioned in the description of fig. 6 above.

Based on the determination result of the road surface characteristic, when the control of the motor torques 212 and 218 in consideration of the low-friction road surface is completed, the controller 102 may store (update) the current values relating to the motor torque control in the memory 170 (230). The current values relating to the motor torque control may include the current position and current time (including date), the determination result of the road surface characteristic, and the motor torque control value.

Further, controller 102 may display the road surface characteristics of the current location on a display of a dashboard of the vehicle (232). In addition to the dashboard, the controller 102 may also be displayed by another display (e.g., a navigation screen or LED lights). Through the display of the road surface characteristics, the passenger can recognize the road surface characteristics where the vehicle is currently located.

According to the embodiment of the present disclosure, the road surface characteristic is determined based on the wheel behavior characteristic during the start control of the motor-equipped eco-vehicle. According to the road characteristic determination result, at the time of starting the vehicle, the vehicle is stably started by controlling the motor torque before occurrence of significant wheel slip.

The disclosed embodiments are merely illustrative of the technical idea. Those skilled in the art will appreciate that various modifications, changes, and substitutions are possible, without departing from the basic characteristics thereof. Therefore, the above disclosed embodiments and drawings are not intended to limit the technical ideas, but to describe the technical spirit of the present disclosure. The scope of the technical idea is not limited by the embodiments and the drawings. The scope of protection is to be construed by the appended claims, and all technical ideas within the equivalent scope are to be construed as being included in the claims.