Environmentally friendly vehicle and steep slope descent control method for environmentally friendly vehicle

Abstract

The present invention relates to an environmentally friendly vehicle and a steep slope descent control method of the environmentally friendly vehicle, so as to be able to travel stably on a downhill road. The method comprises: based on a steep slope descent control request, detecting the inclination of the downhill road, and determining the average inclination and the inclination change amplitude based on the identified downhill road inclination. Based on the average inclination and the inclination change amplitude, determining the first braking force of the main braking source in the motor and hydraulic pressure braking system; and based on the target speed set for the steep slope descent control and the speed of each driving wheel, determining the second braking force of the auxiliary braking source in the motor and hydraulic pressure braking system for each driving wheel. Outputting the first braking force and the second braking force of the corresponding braking source in the motor and hydraulic pressure braking system.

Description

Technical Field

[0001] The invention relates to an environmentally friendly vehicle and a steep slope descent control method of the environmentally friendly vehicle, so as to enable the vehicle to travel smoothly and efficiently on a downhill road. Background Art

[0002] Vehicles developed in recent years include various driving convenience functions implemented by electronic devices. One of these driving convenience functions may be a hill descent control (HDC) function, which will be described in detail in accordance with the relevant technical references. Figure 1 Describe the feature.

[0003] Figure 1 Schematic diagram for explaining the concept of a general HDC function. The HDC function may be a convenient function that is mainly applied to a four-wheel drive (4WD) vehicle that is suitable for driving on a rough road and can independently and automatically control the braking of the four wheels so that the vehicle can travel at a constant speed during driving on a steep road. Therefore, through the corresponding function, the vehicle can travel smoothly even in a bad road condition.

[0004] In recent years, as interest in environmental issues has increased, research has been conducted on environmentally friendly vehicles. Representative examples of environmentally friendly vehicles may be electric vehicles (EVs) and hybrid electric vehicles (HEVs). Generally, a hybrid electric vehicle (HEV) refers to a vehicle that uses two power sources (mainly an engine and a motor). Compared to a vehicle that includes only an internal combustion engine, HEVs have excellent fuel efficiency and engine performance, and are also conducive to reducing emissions, and therefore, HEVs have been actively developed in recent years.

[0005] Hybrid electric vehicles (HEV) and electric vehicles (EV) generally include a drive motor that can apply reverse torque to the motor in a braking or deceleration state to perform a power generation mode, thereby realizing a regenerative braking function that collects the vehicle's kinetic energy to charge the battery. Figure 2 , the regenerative braking function is described.

[0006] Figure 2 An example of the distribution of the braking force of a typical environmentally friendly vehicle is shown. Figure 2 , an environmentally friendly vehicle including a driving motor forms a total braking force by the sum of hydraulic braking for applying a braking torque using friction force based on hydraulic pressure and regenerative braking using reverse torque of a motor. Specifically, generally, a brake controller is configured to calculate a required total braking force, in which case a predetermined portion of the calculated required total braking force is satisfied by regenerative braking, and the remaining insufficient braking force is satisfied by hydraulic braking.

[0007] This distribution of regenerative braking can be performed to maximize utilization within the limits of the power assembly to improve fuel efficiency. However, unlike friction, when a large amount of reverse torque is applied to the motor in a low speed range (e.g., less than about 3 to 5 kph), reverse movement may occur due to inertia, so the regenerative torque is reduced in the low speed range to enhance the stable braking feel. Conventional environmentally friendly vehicles can also implement the HDC function, but the aforementioned regenerative braking cannot be applied to the vehicle, which will be referred to in accordance with the relevant technical reference Figure 3 Give a description.

[0008] Figure 3 Schematic diagram for explaining the problem caused by the application of regenerative braking when a conventional environmentally friendly vehicle implements the HDC function. Figure 3 , when the road inclination changes irregularly around the average inclination, the total braking amount may also change rapidly in order to maintain the same speed. In this case, when regenerative braking is applied according to normal control, the braking performance decreases due to the alternation of hydraulic braking and regenerative braking every time the total braking amount becomes greater than the regenerative braking limit. Therefore, generally, when HDC is applied, environmentally friendly vehicles do not apply regenerative braking. Summary of the invention

[0009] Therefore, the present invention is directed to providing an environmentally friendly vehicle and a method for controlling a steep slope descent of an environmentally friendly vehicle, which can substantially eliminate one or more problems caused by limitations and disadvantages of the related art. An object of the present invention is to provide an environmentally friendly vehicle and a method for controlling a steep slope descent of an environmentally friendly vehicle, for performing a steep slope descent control (HDC) function by a motor.

[0010] Other advantages, purposes and features of the present invention will be presented in part in the following description, and will become apparent to those skilled in the art in part during subsequent review, or may be learned through practice of the present invention. The purposes and other advantages of the present invention may be realized and obtained through the structures specifically pointed out in the written description and claims and the accompanying drawings.

[0011] To achieve these objectives and other advantages, in accordance with the purposes of the present invention, as embodied and broadly described herein, a steep slope descent control method for an environmentally friendly vehicle may include: in response to a steep slope descent control request, identifying the inclination of a downhill road; based on the identified downhill road inclination, determining the average inclination and the magnitude of the inclination change; based on the average inclination and the magnitude of the inclination change, determining a first braking force of a main braking source in a motor and a hydraulic pressure braking system; based on a target speed set for the steep slope descent control and the speed of each driving wheel, determining a second braking force of an auxiliary braking source in a motor and a hydraulic pressure braking system for each driving wheel; and outputting the first braking force and the second braking force of the corresponding braking sources in the motor and the hydraulic pressure braking system.

[0012] In another aspect of the present invention, an environmentally friendly vehicle may include: a first controller configured to identify the inclination of a downhill road in response to a steep slope descent control request; determine the average inclination and the inclination change amplitude based on the identified downhill road inclination; determine the first braking force of the main braking source in the motor and hydraulic pressure brake system based on the average inclination and the inclination change amplitude; determine the second braking force of the auxiliary braking source in the motor and hydraulic pressure brake system for each driving wheel based on the target speed set for the steep slope descent control and the speed of each driving wheel. The vehicle further includes: a second controller and a third controller, the second controller is configured to operate the motor to output any one of the first braking force and the second braking force; the third controller is configured to operate the hydraulic pressure brake system to output the other of the first braking force and the second braking force. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The included drawings are used to provide a further understanding of the present invention and are incorporated into and constitute a part of this application. These drawings illustrate exemplary embodiments of the present invention and together with the description, explain the principles of the present invention. In the drawings:

[0014] Figure 1 is a schematic diagram for explaining the concept of a general hill descent control (HDC) function according to the related art;

[0015] Figure 2 An example of distribution of braking force of a general environmentally friendly vehicle according to the related art is shown;

[0016] Figure 3 is a schematic diagram for explaining a problem caused by application of regenerative braking when a conventional eco-friendly vehicle according to the related art implements an HDC function;

[0017] Figure 4 is a schematic diagram for explaining a powertrain configuration of an environmentally friendly vehicle applicable to an exemplary embodiment of the present invention;

[0018] Figure 5 is a block diagram showing an example of a vehicle configuration according to an exemplary embodiment of the present invention;

[0019] Figure 6 An example of a hill descent control logic model according to an exemplary embodiment of the present invention is shown;

[0020] Figure 7 A schematic diagram showing an example of a form of realizing a total braking amount according to an exemplary embodiment of the present invention;

[0021] Figure 8 A schematic diagram showing another example of a steep slope descent control logic model according to an exemplary embodiment of the present invention;

[0022] Fig. 9 A schematic diagram showing another example of a form of realizing the total braking amount according to an exemplary embodiment of the present invention;

[0023] Fig.10 is a flowchart showing an example of a steep hill descent control step according to an exemplary embodiment of the present invention;

[0024] Fig.11 is a schematic diagram for explaining physical factors for identifying a downhill road inclination according to an exemplary embodiment of the present invention; and

[0025] Fig.12 2 is a schematic diagram for explaining an average inclination according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0026] It should be understood that the term "vehicle" or "vehicular" or other similar terms used herein generally include motor vehicles, such as passenger automobiles including sport utility vehicles (SUVs), buses, trucks, various commercial vehicles, ships including various boats, marine vessels, aircraft, etc., and include hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other alternative fuel vehicles (e.g., fuels derived from non-petroleum energy sources). As referred to herein, a hybrid vehicle is a vehicle having two or more power sources, such as both gasoline-powered and electric-powered vehicles.

[0027] Although the exemplary embodiments are described as using multiple units to perform the exemplary processes, it should be understood that the exemplary processes can also be performed by one or more modules. In addition, it should be understood that the term controller / control unit represents a hardware device including a memory and a processor. The memory is configured to store the modules, and the processor is specifically configured to execute the modules to perform one or more processes described further below.

[0028] In addition, the control logic of the present invention can be implemented as a non-transitory computer readable medium on a computer readable medium, which contains executable program instructions executed by a processor, a controller / controller unit, etc. Examples of computer readable media include, but are not limited to, ROM, RAM, compact disc (CD)-ROM, magnetic tape, floppy disk, flash drive, smart card, and optical data storage device. The computer readable recording medium can also be distributed on a network-connected computer system so that the computer readable medium is stored and executed in a distributed manner, for example, through a telematics server or a controller area network (CAN).

[0029] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to limit the present invention. As used herein, the singular forms "one", "an" and "the" are intended to also include plural forms, unless the context clearly states otherwise. It will also be understood that when the terms "include" and / or "include" are used in this specification, it is indicated that the features, numerical values, steps, operations, elements and / or components exist, but do not exclude the presence or addition of one or more other features, numerical values, steps, operations, elements, components and / or their groups. As used herein, the term "and / or" includes any and all combinations of one or more related enumerated items.

[0030] Unless otherwise stated or apparent from the context, the term "about" as used herein is understood to be within the normal tolerance range in the art, such as within 2 standard deviations of the average. "About" may be understood to be within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise apparent from the context, all numerical values ​​provided herein are modified by the term "about".

[0031] The exemplary embodiments of the present invention are described in detail so that those skilled in the art can easily implement with reference to the accompanying drawings. However, the present invention can be implemented in different ways and is not limited to these embodiments. In order to clearly describe the present invention, components that are not related to the description are omitted in the accompanying drawings, and the same reference numerals in the specification represent the same elements. Throughout the drawings and the specification, the same reference numerals will be used to represent the same components.

[0032] According to the proposal of an exemplary embodiment of the present invention, during downhill road driving, a main braking source and an auxiliary braking source can be determined, the main braking source is used to provide continuous braking force according to the configuration of the powertrain of the environmentally friendly vehicle, and the auxiliary braking source is used to independently distribute the braking force to each wheel and meet the total braking force to utilize the braking force to assist the main braking source. In this case, any one of the main braking source and the auxiliary braking source can be achieved through regenerative braking using an electric motor.

[0033] Before describing the steep slope descent control method according to an exemplary embodiment of the present invention, reference will be made to Figure 4 A configuration of a power train of an environmentally friendly vehicle applicable to the exemplary embodiment is described. Figure 4 is a schematic diagram for explaining the configuration of a power train of an environmentally friendly vehicle applicable to an exemplary embodiment of the present invention.

[0034] Figure 4 Two configurations of powertrains for an environmentally friendly vehicle capable of four-wheel drive (4WD) are shown. Figure 4 The powertrain configuration shown uses an electric motor and is therefore also referred to as "e4WD".

[0035] first, Figure 4 The powertrain shown on the left side of can be configured in such a way that the front wheels are driven by the engine and the rear wheels are driven by one motor. Specifically, the rear wheels are connected to the motor through a differential (Diff.), so that the same torque can be transmitted to both wheels at the rear wheels. Therefore, in the powertrain configuration, regenerative braking torque cannot be applied to each wheel individually, so that hydraulic braking can be an auxiliary braking source and regenerative braking can be a main braking source.

[0036] Then, Figure 4 The powertrain shown on the right side of the embodiment may have a drive body similar to the drive body of the front and rear wheels of the powertrain shown on the left side. However, the two wheels at the rear wheel may each include a motor (e.g., an in-wheel motor). In other words, the left wheel may be driven by motor 1 and the right wheel may be driven by motor 2. Therefore, in the powertrain configuration, the regenerative braking torque may be applied independently to each wheel, so that the hydraulic braking may be the main braking source and the regenerative braking may be the auxiliary braking source. Of course, it may also be used in reverse.

[0037] Figure 4 The powertrain shown includes an engine and can thus be implemented in the form of a hybrid electric vehicle (HEV), but the exemplary embodiment of the present invention can also be applied to an electric vehicle (EV) without an engine as long as the current situation is a steep hill descent control situation in which only braking force is applied without driving force.

[0038] Then, reference will be made to Figure 5 A vehicle configuration for executing a hill descent control method according to an exemplary embodiment is described. Figure 5 2 is a block diagram showing an example of a vehicle configuration according to an exemplary embodiment of the present invention. Figure 5, the environmentally friendly vehicle according to the exemplary embodiment may include: a driver manipulation unit 510, a hybrid control unit (HCU) 520, a navigation system 530, a brake controller 540, a hydraulic pressure brake system 550, a motor controller 560, an inverter 570, and a drive motor 580. Each component may be operated by a general controller having a processor and a memory.

[0039] Specifically, as long as the driver manipulation unit 510 can receive a command from the driver for determining whether to set the HDC function, the driver manipulation unit 510 may not be limited to a specific form. When the driver manipulation unit 510 sets the HDC function, the HCU 520 may be configured to determine a main braking source and an auxiliary braking source of a braking force for achieving a tracking target speed based on a road inclination, and may be configured to determine and correct the braking force of each braking source.

[0040] The navigation system 530 may be configured to provide the hybrid controller 520 with information on the inclination of the road. In some exemplary embodiments, the navigation system 530 may also be omitted. The brake controller 540 may be implemented in the form of an electronic brake system (EBS), and according to the determination result of the hybrid controller 520, the brake controller 540 may be configured to operate the hydraulic pressure brake system 550 to perform the hydraulic braking amount.

[0041] The motor control unit (MCU) 560 may be configured to operate the inverter 570, which supplies alternating current (AC) power to the drive motor 580 based on the determination result of the hybrid controller 520, and the motor control unit (MCU) 560 may be configured to operate the drive motor 580 to perform regenerative braking. Figure 4 The vehicle configuration shown on the left side of FIG. 1 is configured with a drive motor 580, which can be Figure 4 In the vehicle configuration shown on the right side of FIG. , a total of two drive motors 580 are configured for each wheel.

[0042] Subsequently, the hill descent control logic will be described based on the above-mentioned vehicle configuration. Figure 6 An example of a steep slope descent control logic model according to an exemplary embodiment of the present invention is shown. Figure 4 When the powertrain configuration cannot use the motor to adjust the torque of the drive wheels on the opposite sides separately, it can be applied Figure 6 The logical model shown.

[0043] In the control logic model, the motor can be configured to provide an average braking force based on the average inclination, and the hydraulic pressure brake system of each driving wheel can be configured to perform individual control on the braking force of each driving wheel, including posture control as feedback control. In other words, in this control logic model, the motor can be the main braking source and the hydraulic pressure brake system can be the auxiliary braking source.

[0044] refer to Figure 6 The driving environment model 610 may be generated by sensor information such as a target driving force, a speed of each wheel, a vertical / horizontal acceleration, or a steering angle. When the driving environment model 610 obtains the average inclination information of the current driving road, the average braking force based on the vehicle model 630 may be obtained using the target speed. When the control margin is determined based on the inclination change (i.e., the inclination change amplitude) obtained by the driving environment model 610, the regenerative braking force performed by the motor 640 may be determined by feedforward control based on the difference between the average braking force and the control margin.

[0045] The amount of hydraulic braking to be performed by the hydraulic brake 660 of each driving wheel can be obtained by feeding back the speed of each driving wheel based on the target speed and the behavior of the actual vehicle 670 through the proportional-integral (PI) control 650. Specifically, the feedback information of the PI control 650 can be basic information for correcting the control margin 620. The behavior of the vehicle 670 based on the total amount of braking performed by the motor 640 and the hydraulic brake 660 of each driving wheel can be fed back again on the speed of each driving wheel through the observer 680.

[0046] Will refer to Figure 7 Description based on Figure 6 The control logic model of the braking form is shown. Figure 7 FIG. 2 is a schematic diagram showing an example of a form of realizing a total braking amount according to an exemplary embodiment of the present invention. Figure 7 , the braking amount obtained by subtracting the control margin from the average braking amount can be performed by regenerative braking, and the total braking amount can be satisfied by the change in hydraulic braking amount. Therefore, regenerative braking can also be applied to the HDC function, and hydraulic braking and regenerative braking do not alternate, so that no Figure 3 The problem shown.

[0047] Figure 8 FIG. 2 is a schematic diagram showing another example of a steep slope descent control logic model according to an exemplary embodiment of the present invention. Figure 4 On the right side, when the powertrain configuration is capable of using the motor to adjust the torque of the drive wheels on the opposite sides respectively, it can be applied Figure 8The logic model shown. In the control logic model, the hydraulic brake can be configured to provide an average braking force based on the average inclination, and the motor of each driving wheel can be configured to perform individual control of the braking force of each driving wheel, including posture control as feedback control. In other words, in this control logic model, the motor can be an auxiliary braking source and the hydraulic pressure brake system can be a main braking source.

[0048] Will Figure 8 The model configuration and Figure 6 The model configuration is the same except that Figure 8 The feedback control target of the PI control 650 is the motor control 660' for each driving wheel, and the hydraulic brake 640' is used instead as the execution subject of the average braking force, so repeated description is omitted.

[0049] Will refer to Fig. 9 Description based on Figure 8 The control logic model of the braking form is shown. Fig. 9 FIG. 2 is a schematic diagram showing another example of a form of realizing the total braking amount according to an exemplary embodiment of the present invention. Fig. 9 , the braking amount obtained by subtracting the control margin from the average braking amount can be performed by hydraulic braking, and the total braking amount can be satisfied by the change in the regenerative braking amount. Therefore, regenerative braking can also be applied to the HDC function, and hydraulic braking and regenerative braking do not alternate, so that no Figure 3 The problem shown.

[0050] Next, the above-mentioned control steps will be described with reference to the flowchart. Fig.10 FIG. 2 is a flowchart showing an example of a steep slope descent control step according to an exemplary embodiment of the present invention. Fig.10 First, the hybrid controller 520 may be configured to determine the driver's HDC driving intention (S1010). In this step, the HDC driving intention may be determined based on receiving a command for activating the HDC function input through the driver manipulation unit 510.

[0051] When there is a driver's HDC driving intention (ie, when hill descent control is required), the hybrid controller 520 may be configured to identify a downhill road inclination (S1020). The downhill road inclination may be estimated by an acceleration sensor value or a wheel speed value measured by a wheel speed sensor of each wheel. Fig.11 2 is a schematic diagram for explaining physical factors for identifying a downhill road inclination according to an exemplary embodiment of the present invention.

[0052] refer to Fig.11, when the vehicle is traveling on a downhill road, the acceleration sensor value detected by the acceleration sensor may be a value obtained by adding the driving direction component of the gravity acceleration to the wheel acceleration. Therefore, when the wheel acceleration is subtracted from the acceleration sensor value, the driving direction component of the gravity acceleration may be obtained, and the inclination may be obtained according to "arcsin (acceleration sensor value - wheel acceleration)". Specifically, the wheel acceleration may be obtained according to "d / dt (average wheel speed of four wheels)". This step may be performed within a predetermined period, or may be performed continuously in real time. This step may also be performed using detailed map data instead of the sensor value, or using detailed map data and the sensor value. Specifically, the detailed map data may be obtained from the navigation system 530, or may be obtained from an external object through V2X communication.

[0053] Reference again Fig.10 , the hybrid controller 520 may be configured to obtain an average downhill road inclination based on the downhill road inclination to estimate the change range (S1030). Fig.12 Describes the average value of the downhill road inclination, that is, the average gradient. Fig.12 Schematic diagram for explaining the average inclination according to an exemplary embodiment of the present invention. Fig.12 , the hybrid controller 520 may be configured to estimate the inclination average value and the inclination variation amplitude within a moving window having a predetermined length and moving over time.

[0054] Specifically, the downhill road inclination average value may be an average of the measured inclination values ​​included in the window, and the variation range may be calculated based on data having a predetermined reliability in the distribution of the values ​​measured in the window (e.g., data corresponding to about 90% of the measured inclination values ​​based on the average inclination). This step may be a step of calculating the deviation range of the braking force irregularly generated on each wheel in the future with the variation range of the road inclination so far, and the estimated value of the variation range may correspond to Figures 6 to 9 The control margin in .

[0055] Reference again Fig.10 , the hybrid controller 520 can be configured to determine whether regenerative braking can be achieved through the motor (S1040). When the battery state of charge (SoC) is too high, or the power components such as the motor 580 / inverter 570 / battery are in a high temperature state, regenerative braking cannot be achieved, so the controller can be configured to determine whether regenerative braking can be achieved through the motor. As a result of the determination, when regenerative braking cannot be achieved ("No" of S1040), the hybrid controller 520 can be configured to perform a normal HDC function to achieve total braking torque using only friction braking without applying regenerative braking (S1050).

[0056] On the other hand, when regenerative braking is possible (“Yes” in S1040), the hybrid controller 520 may be configured to select a main braking source and an auxiliary braking source (S1060). Specifically, the braking system for independently distributing the braking force to each wheel may be the auxiliary braking source, and the braking system that continuously provides the maximum braking force may be the main braking source. For example, Figure 4 In the power transmission system shown on the left side of FIG, the motor can be the main braking source, and the hydraulic pressure braking system can be the auxiliary braking source. Figure 4 In the power transmission system shown on the right side of , the motor can be the auxiliary braking source and the hydraulic pressure braking system can be the main braking source.

[0057] The hybrid control unit (HCU) 520 may be configured to determine the braking force of each of the main braking source and the auxiliary braking source when the function of each braking source is determined (S1070). Specifically, the main braking source may be operated using a feedforward method to satisfy the braking force obtained by excluding the estimated value of the road variation from the average inclination. For example, the braking force managed by the main braking source may be obtained according to "M*g*sin(inclination-variation)", where M is the vehicle mass and g is the gravitational acceleration.

[0058] The auxiliary braking source can achieve braking force based on feedback that enables each drive wheel to travel at a preset target speed in the HDC function. The target speed preset in the HDC function can be a constant value of about 3 to 8 kph, but is not limited to this. The speed error of the feedback control can be a value obtained by subtracting the current linear speed of the wheel from the target speed, and the braking torque can be determined separately for each drive wheel to reduce the speed error. When the hybrid controller determines the braking force (i.e., braking torque) of each braking source, each determined braking torque can be sent to the brake controller 540 and the motor controller 560, and each controller can be configured to output the friction braking force and regenerative braking force corresponding to the determined braking torque.

[0059] According to the exemplary embodiment of the present invention described so far, the braking force for HDC control performed by the hydraulic pressure system and the mechanical friction material can be distributed to the drive motor, and therefore, the HDC control can be realized by the motor, thereby enhancing the regulation stability. The exemplary embodiment of the present invention can reduce the burden of hydraulic pressure braking, and can be advantageous in terms of temperature management and durability of the friction material. In addition, energy can be collected even in extreme road conditions, so that it can be expected that the climbing ability on the next uphill road will be enhanced, and fuel efficiency can also be improved.

[0060] The above-described environmentally friendly vehicle associated with at least one embodiment of the present invention can achieve steep slope descent control using a motor, thereby enhancing regulation stability. The exemplary embodiment of the present invention can reduce the burden of hydraulic pressure braking in downhill road conditions, and can be advantageous in terms of temperature management and durability of friction materials. In addition, energy can be harvested even in extreme road conditions, and fuel efficiency can also be improved.

[0061] Those skilled in the art will appreciate that the effects achievable through the present invention are not limited to the effects that have been specifically described above, and other advantages of the present invention will be more clearly understood from the detailed description.

[0062] The present invention described above may also be implemented as computer-readable code stored on a non-transient computer-readable recording medium. A non-transient computer-readable recording medium is any data storage device that can store data that can be subsequently read by a computer. Examples of non-transient computer-readable recording media include a hard disk drive (HDD), a solid state drive (SSD), a silicon disc drive (SDD), a read-only memory (ROM), a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like.

[0063] It will be apparent to those skilled in the art that various modifications and changes can be made to the present invention without departing from the spirit or scope of the present invention. Therefore, the present invention is intended to cover the modifications and changes of the present invention provided, and the modifications and changes of the present invention are within the scope of the appended claims and their equivalents.

Claims

1. A steep slope descent control method for an environmentally friendly vehicle, comprising: In response to a hill descent control request, the controller detects a downhill road inclination; Based on the identified downhill road inclination, the controller determines an average inclination and an inclination change amplitude; Based on the average inclination and the inclination change amplitude, the controller determines a first braking force of a main braking source in a motor or hydraulic pressure braking system; determining, by the controller, a second braking force of an auxiliary braking source in a motor or hydraulic pressure braking system for each driving wheel based on a target speed set for the hill descent control and a speed of each driving wheel; The controller outputs the first braking force and the second braking force of the corresponding braking sources in the motor and the hydraulic pressure brake system; Here, the first braking force corresponds to a value obtained by subtracting a control margin corresponding to the gradient change amplitude from a braking force corresponding to the average gradient.

2. The method according to claim 1, wherein: When the motor is connected to each driving wheel through a differential, the main braking source is the motor and the auxiliary braking source is the hydraulic pressure brake system.

3. The method according to claim 1, wherein: When two or more motors are connected to each driving wheel, the main braking source is a hydraulic pressure braking system, and the auxiliary braking source is the two or more motors connected to each driving wheel.

4. The method according to claim 1, wherein: The motor is configured to output any one of a first braking force and a second braking force through regenerative braking.

5. The method according to claim 1, wherein: Detecting downhill road inclination includes: obtaining, by a controller, wheel acceleration based on an average speed of four wheels included in the environmentally friendly vehicle; The downhill road inclination is obtained by the controller based on a value obtained by subtracting the wheel acceleration from the acceleration sensor value.

6. The method according to claim 1, wherein: Determining the average slope and slope variation involves: The controller obtains the average inclination by using the average value of the inclination of the downhill road existing in the moving window with a predetermined time length; The controller obtains the gradient variation amplitude based on the downhill road gradient distribution with a predetermined reliability based on the average gradient within the moving window.

7. The method according to claim 1, wherein: Determining the second braking force includes: The controller obtains a speed error of each driving wheel by subtracting a linear speed of the wheel obtained based on the speed of each driving wheel from the target speed; A second braking force is determined by the controller for each driven wheel to reduce the speed error.

8. The method according to claim 1, wherein: The first braking force is determined in the form of feedforward control; the second braking force is determined in the form of feedback control. 9 . A non-transitory computer-readable recording medium having recorded thereon a program for executing the hill descent control method for an environmentally-friendly vehicle of claim 1 .

10. An environmentally friendly vehicle, comprising: The first controller is configured as follows: In response to a hill descent control request, detecting a downhill road inclination; Based on the identified downhill road inclination, determining an average inclination and an inclination change magnitude; Determine a first braking force of a main braking source in a motor or hydraulic pressure braking system based on the average inclination and the inclination change amplitude; determining a second braking force of an auxiliary braking source in a motor or hydraulic pressure braking system for each driving wheel based on a target speed set for the hill descent control and a speed of each driving wheel; a second controller configured to operate the motor to output an output corresponding to any one of the first braking force and the second braking force; as well as a third controller configured to operate the hydraulic pressure brake system to output the other corresponding to the first braking force and the second braking force; The first braking force corresponds to a value obtained by subtracting a control margin corresponding to a variation range of the inclination from a braking force corresponding to an average inclination.

11. The environmentally friendly vehicle according to claim 10, wherein: When the motor is connected to each driving wheel through a differential, the main braking source is the motor and the auxiliary braking source is the hydraulic pressure brake system.

12. The environmentally friendly vehicle according to claim 10, wherein: When two or more motors are connected to each driving wheel, the main braking source is a hydraulic pressure braking system, and the auxiliary braking source is the two or more motors connected to each driving wheel.

13. The environmentally friendly vehicle according to claim 10, wherein: The motor outputs any one of a first braking force and a second braking force through regenerative braking.

14. The environmentally friendly vehicle according to claim 10, wherein: The first controller is configured to obtain wheel acceleration based on an average speed of four wheels included in the environmentally-friendly vehicle, and obtain a downhill road inclination based on a value obtained by subtracting the wheel acceleration from an acceleration sensor value.

15. The environmentally friendly vehicle according to claim 10, wherein: The first controller is configured to obtain an average inclination by using an average value of downhill road inclinations within a moving window with a predetermined time length, and to obtain an inclination variation amplitude based on a downhill road inclination distribution with a predetermined reliability based on the average inclination within the moving window.

16. The environmentally friendly vehicle according to claim 10, wherein: The first controller is configured to obtain a speed error of each driving wheel by subtracting a linear speed of the wheel obtained based on the speed of each driving wheel from a target speed, and determine a second braking force for each driving wheel to reduce the speed error.

17. The environmentally friendly vehicle according to claim 10, wherein: The first braking force is determined in the form of feedforward control, and the second braking force is determined in the form of feedback control.

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