Apparatus and method for controlling steering and speed of each wheel of vehicle using turning center

Abstract

An embodiment method of controlling steering and speed of each wheel of a vehicle based on a turning center includes calculating a turning center point of the vehicle based on driving information of the vehicle, calculating a turning radius of the vehicle, a steering angle of each wheel, a turning radius of each wheel based on the turning center point, and controlling steering and speed of each wheel based on the turning center point. Calculating a power frequency for each wheel based on the turning radius and the required speed, and during a time period in which the vehicle is moved based on a steering angle for each wheel and the power frequency for each wheel, the steering angle of each wheel is output into a corresponding steering device and power is applied to a motor in the corresponding wheel at the power frequency of each wheel.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Korean Patent Application No. 10-2023-0113991, filed on August 29, 2023, which is hereby incorporated herein by reference. Technical Field

[0003] The present disclosure relates to an apparatus and method for controlling the steering and speed of each wheel of a vehicle based on a turn center. Background Art

[0004] The descriptions in this section merely provide background information related to embodiments of the present disclosure and do not necessarily constitute related art.

[0005] The steering device of a vehicle is a system for steering the vehicle, and the rear wheel steering (RWS) system is a system for improving the maneuverability of the vehicle at low speeds and the stability of the vehicle when it is traveling at high speeds by adjusting the steering angle of the rear wheels based on the steering angle of the front wheels of the vehicle and the speed of the vehicle.

[0006] An in-wheel motor refers to an electric motor mounted on a wheel to directly drive the wheels of the vehicle. In the case of a conventional vehicle, a central motor or engine is mounted in the engine compartment of the vehicle so that the power of the engine is delivered to the wheels through various shafts and gear devices. In contrast, in the case of an in-wheel motor system, the driving force of the motor is delivered directly to the wheels of the vehicle, thereby improving power usage efficiency and reducing vehicle weight by eliminating a large drive motor mounted in the engine compartment of the vehicle and using the space in the engine compartment for other purposes.

[0007] Recently, a system capable of independently controlling the steering and driving of each of the four wheels of a vehicle has been developed. However, when a conventional rear wheel steering system and an in-wheel motor system are simply integrated, there is a problem that the vehicle cannot be stably controlled due to a complex structure and errors in data sensed by various sensors.

[0008] Therefore, a method of stably controlling the steering and acceleration / deceleration of individual wheels with a simple structure is required. Summary of the invention

[0009] Embodiments of the present disclosure provide an apparatus and method for calculating a turning center of a vehicle based on driving information and controlling the steering and speed of individual wheels based on the turning center.

[0010] Other embodiments of the present disclosure provide a method of adjusting the height of a suspension of a vehicle based on a turning center of the vehicle.

[0011] The embodiments of the present disclosure are not limited to the above-described embodiments, and other embodiments not mentioned herein will be clearly understood by those skilled in the art from the following description.

[0012] One embodiment of the present disclosure provides a method for controlling the steering and speed of each wheel of a vehicle based on a turning center, comprising the following steps: calculating the turning center point of the vehicle based on driving information of the vehicle, calculating the turning radius of the vehicle, the steering angle of each wheel, and the turning radius of each wheel based on the turning center point, calculating the power frequency of each wheel based on the turning radius and the required speed, and during a time period in which the vehicle is moved based on the steering angle of each wheel and the power frequency of each wheel, outputting the steering angle of each wheel to a corresponding steering device and applying power to the corresponding in-wheel motor at the power frequency of each wheel.

[0013] The driving information of the vehicle includes a driving track to be followed by the vehicle or an angle of a steering wheel input by a user.

[0014] Another embodiment of the present disclosure provides an apparatus for controlling the steering and speed of each wheel of a vehicle based on a turning center, comprising: an in-wheel motor installed on each wheel of the vehicle; a steering device for performing the steering of each wheel of the vehicle; and a controller for controlling the steering angle and the speed of each wheel of the vehicle, wherein the controller comprises: a turning center calculation unit, the turning center calculation unit being configured to calculate the turning center point of the vehicle based on the driving information of the vehicle; a steering angle calculation unit, the steering angle calculation unit being configured to calculate the turning radius of the vehicle, the steering angle of each wheel, and the turning radius of each wheel based on the turning center point; a power frequency calculation unit, the power frequency calculation unit being configured to calculate the power frequency of each wheel based on the turning radius and the required speed of each wheel; and an output unit, the output unit being configured to: during a time period in which the vehicle is moved based on the steering angle of each wheel and the power frequency of each wheel, output the steering angle of each wheel to the corresponding steering device and apply power to the corresponding in-wheel motor at the power frequency of each wheel.

[0015] According to the embodiments of the present disclosure, a structure for controlling the steering and speed of individual wheels may be simplified.

[0016] According to the embodiments of the present disclosure, the driving stability and convenience of the vehicle can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1is an exemplary diagram of a vehicle having some components of an apparatus for controlling the steering and speed of each wheel of the vehicle based on a turning center according to an embodiment of the present disclosure.

[0018] Figures 2A-2C is a diagram showing how the turning center of a vehicle changes depending on how each wheel is steered.

[0019] Figure 3 is an exemplary diagram of a process of calculating a turning center of a vehicle based on the steering angles of the front and rear wheels.

[0020] Figure 4 is a diagram of components of an apparatus for controlling the steering and speed of each wheel of a vehicle based on a turning center according to an embodiment of the present disclosure.

[0021] Figure 5A and Figure 5B is an exemplary diagram showing coordinate transformation for calculating a turning center under the condition of autonomous driving in which a driving trajectory to be followed by a vehicle is given as a set of point coordinates according to an embodiment of the present disclosure.

[0022] Figure 6 is an exemplary diagram illustrating a process of calculating a turning center under the condition of autonomous driving in which a driving trajectory to be followed by a vehicle is given as a set of point coordinates according to an embodiment of the present disclosure.

[0023] Figure 7 is an exemplary diagram illustrating a process of calculating a turning center when a user steers a vehicle by himself through a steering wheel in a case where only front wheels can be steered according to another embodiment of the present disclosure.

[0024] Figure 8 is an exemplary diagram illustrating a process of calculating a steering angle based on a turning center of a vehicle and a position of each wheel according to an embodiment of the present disclosure.

[0025] Fig. 9 is an exemplary diagram illustrating a process of calculating an adjusted height of a suspension of a vehicle based on a turning radius and a required speed of the vehicle according to an embodiment of the present disclosure.

[0026] Fig.10 is a flowchart illustrating a control process for each scenario according to an embodiment of the present disclosure.

[0027] Fig.11 is a flowchart illustrating a process of controlling the steering and speed of each wheel of a vehicle based on a turning center according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0028] Hereinafter, some embodiments of the present disclosure will be described in detail with reference to the attached illustrative drawings. In the following description, although the elements are shown in different drawings, the same reference numerals preferably represent the same elements. In addition, in the following description of some embodiments, for the sake of clarity and brevity, the detailed description of the relevant known parts and functions will be omitted when it is considered that the detailed description of the relevant known parts and functions will obscure the subject matter of the embodiments of the present disclosure.

[0029] Various ordinal numbers or letter codes (such as first, second, i), ii), a), b), etc.) are used only to distinguish one component from another rather than to imply or suggest the substance, order or sequence of the components. Throughout the specification, when a part "includes" or "contains" a component, the part means to also include other components rather than exclude other components, unless otherwise explicitly stated. Terms such as "unit", "module", etc. refer to one or more units for processing at least one function or operation, which can be implemented by hardware, software or a combination thereof.

[0030] The following description of the embodiments of the present disclosure in conjunction with the accompanying drawings is intended to describe exemplary embodiments of the present disclosure, and is not intended to identify the only embodiment in which the technical ideas of the embodiments of the present disclosure can be practiced.

[0031] The term “turning center” in this disclosure refers to the turning center point outside the vehicle and is used interchangeably with the term “rotation center.” The term “turning radius” is used interchangeably with the term “rotation radius.”

[0032] In the present disclosure, when the wheel turns right based on the axis in the direction of vehicle travel, the steering angle of each wheel has a negative value, and when the wheel turns left based on the axis in the direction of vehicle travel, the steering angle of each wheel has a positive value.

[0033] Figure 1 is an exemplary diagram of a vehicle having some components of an apparatus for controlling the steering and speed of each wheel of the vehicle based on a turning center according to an embodiment of the present disclosure.

[0034] See also Figure 1 The vehicle 10 according to the embodiment of the present disclosure may include steering devices 100a, 100b, 100c and 100d, in-wheel motors 200a, 200b, 200c and 200d, and a controller 300. The vehicle 10 may also include various sensors (not shown) and a device 400 for controlling a suspension to obtain driving information.

[0035] The steering apparatuses 100 a , 100 b , 100 c , and 100 d may perform steering by receiving information on a steering angle of each wheel from the controller 300 .

[0036] In-wheel motors 200 a , 200 b , 200 c , and 200 d may be installed in each wheel of vehicle 10 , respectively, and may be accelerated / decelerated by receiving AC power at a power frequency of each wheel from controller 300 .

[0037] The controller 300 may steer each wheel based on a turning angle of each wheel calculated based on a turning center of an expected driving trajectory given during autonomous parking or driving. The controller 300 may control the speed of each wheel by controlling the power frequency of the motor in each wheel based on the speed of each wheel extracted based on the tracking speed and the turning center.

[0038] refer to Figure 2A , Figure 2B and Figure 2C , will describe how the vehicle's turning center changes depending on how each wheel is turned. Figure 2A The turning center of a vehicle with a rear wheel steering system is shown when the steering direction of the rear wheels is the same as the steering direction of the front wheels (i.e., when they are in the same phase). At high speeds, the front and rear wheels can be controlled to be in phase with each other, thereby improving driving stability. Figure 2B The turning center is shown for a vehicle without a rear wheel steering system, ie a vehicle in which only the front wheels are steerable. Figure 2C The turning center of a vehicle with a rear wheel steering system is shown when the steering angle of the rear wheels is opposite to the steering angle of the front wheels (i.e., out of phase). At low speeds, the front and rear wheels can be controlled out of phase with each other so that the turning radius of the vehicle can be reduced, thereby enhancing maneuverability.

[0039] refer to Figure 3 , an example of a process of calculating a turning center of a vehicle based on the steering angles of the front and rear wheels will be described. With the center of the vehicle as a reference point, a coordinate in which the x-axis is along the longitudinal direction of the vehicle and the y-axis is along the lateral direction of the vehicle is assumed.

[0040] See also Figure 3 , the coordinates of the left front (FL) wheel of the vehicle are (m / 2, w / 2), the coordinates of the right front (FR) wheel are (m / 2, -w / 2), the coordinates of the left rear (RL) wheel are (-m / 2, w / 2), and the coordinates of the right rear (RR) wheel are (-m / 2, -w / 2). Where "m" represents the wheelbase of the vehicle, and "w" represents the track width of the vehicle. The shaded trapezoid represents the area where the turning center of the vehicle may exist based on the steering angle of the front wheels / rear wheels when the vehicle turns right.

[0041] When the steering angle of the FR wheel is given as α and the steering angle of the RR wheel is given as β, the turning center of the vehicle may be located at the intersection of straight lines ① and ②. Here, the equation of each of straight lines ① and ② may be as shown in Equation 1, and the x and y coordinates of the intersection of the two straight lines may be calculated as shown in Equation 2.

[0042] Equation 1 :

[0043]

[0044] Equation 2:

[0045]

[0046] Figure 4 is a diagram of components of an apparatus for controlling the steering and speed of each wheel of a vehicle based on a turning center according to an embodiment of the present disclosure.

[0047] See also Figure 4 According to an embodiment of the present disclosure, a device for controlling the steering and speed of each wheel of a vehicle based on a turning center (hereinafter referred to as "the device for controlling the steering and speed of each wheel") can control the steering and speed of each wheel based on the turning center of the vehicle and can control the process of adjusting the height of the suspension of the vehicle. To this end, the device for controlling the steering and speed of each wheel may include steering devices 100a, 100b, 100c, 100d, in-wheel motors 200a, 200b, 200c, 200d, and a controller 300. The device for controlling the steering and speed of each wheel may also include a device 400 for controlling the suspension.

[0048] The components of the device for controlling the steering and speed of each wheel may send or receive signals or data using various communication protocols within the vehicle. Here, the communication protocol may include at least one of a controller area network (CAN), a CAN with flexible data rate (CAN FD), a local interconnect network (LIN), FlexRay, and Ethernet.

[0049] The steering apparatuses 100 a , 100 b , 100 c , and 100 d , and the in-wheel motors 200 a , 200 b , 200 c , and 200 d have been described above.

[0050] Using the turning center point of the vehicle calculated based on the information about the vehicle's travel, the controller 300 may determine the steering angle of each wheel and output it to the steering device, and may determine the power frequency of each wheel and apply it to the in-wheel motor. The controller 300 may determine the height of the suspension of the vehicle and output it to the device 400 for controlling the suspension. To this end, the controller 300 may include all or some of the turning center calculation unit 310, the steering angle calculation unit 320, the power frequency calculation unit 330, the suspension height calculation unit 340, the output unit 350, and the inverter 360.

[0051] The controller 300 may be placed inside the vehicle and may be an electronic control unit (ECU). The controller 300 may include a hardware processor and a memory for storing commands, a lookup table (LUT), etc. for executing the controller 300, but is not limited thereto. The controller 300 may include all components for comprehensively controlling the device for controlling the steering and speed of each wheel.

[0052] The turning center calculation unit 310 may calculate the turning center of the vehicle based on information about the driving of the vehicle. Here, the information about the driving of the vehicle may include a driving track to be followed by the vehicle, an angle of a steering wheel input by a user, a vehicle speed, and the like.

[0053] According to an embodiment of the present disclosure, a process of calculating a turning center under the condition of autonomous driving in which a driving trajectory to be followed by a vehicle is given as a set of point coordinates is as follows: The point coordinates of the driving trajectory may be managed as a world coordinate system.

[0054] The turning center calculation unit 310 may calculate the turning center based on data about the current position of the vehicle (current position and current direction) and data about the target position of the vehicle (target position and target direction).

[0055] The turning center calculation unit 310 may set a local coordinate system using the current position of the vehicle as a reference point. That is, the local coordinate system may be set with the center of the vehicle at the current position as a reference point and the x-axis along the longitudinal direction of the vehicle.

[0056] The turning center calculation unit 310 can extract data about the target position to which the vehicle will move from a given driving trajectory. Specifically, the turning center calculation unit 310 can select two points P1 (px1, py1) and P2 (px2, py2) from the driving trajectory and convert them into a local coordinate system. The two points can be selected based on the specifications of the vehicle and / or the speed of the vehicle. When the driving trajectory includes more point coordinates, two points (P1 and P2) can be selected by sampling the point coordinates regularly or appropriately to reduce the amount of calculation.

[0057] The center P (px, py) of the two points and the slope a of the straight line passing through the two points can be calculated using the following equation 3. The center P can represent the target position, and the slope a can represent the target direction in which the vehicle is traveling. The equation of the straight line passing through the two points (P1 and P2) can be derived based on the center P and the slope a.

[0058] Equation 3 :

[0059] P(px,py)=((px1+px2) / 2,(py1+py2) / 2)

[0060] a=(py2-py1) / (px2-px1)

[0061] When the vehicle moves from its current position to its target position, a new local coordinate system may be set with the center of the vehicle at the target position as the reference point and the x-axis along the longitudinal direction of the vehicle, and the above process may be repeated.

[0062] Figure 5A Setting of a local coordinate system based on a current position (position A) and coordinate transformation of two points (P1 and P2) corresponding to a target position (position B) are shown. Figure 5B Setting a new local coordinate system based on position B and coordinate transformation of two points (P3 and P4) corresponding to the next target position (position C) when the vehicle moves from position A to position B are shown.

[0063] The turning center calculation unit 310 may calculate the turning center of the vehicle based on the current position data and the target position data of the vehicle. Figure 6 Describe in detail the process of calculating the turn center.

[0064] First, a point (d, 0) and a point (pdx, pdy) at the same distance (d) from the center of the vehicle in the traveling direction or longitudinal direction of the vehicle may be selected at each of the current position (position A) and the target position (position B), and a straight line from each point Can be drawn perpendicular to the direction the vehicle is traveling at each point.

[0065] When two straight lines and When the measured lengths from the intersecting point (s, t) to each of the two points (d, 0) and (pdx, pdy) have the same value, the point (s, t) may be considered the turning center of the vehicle.

[0066] A straight line can be obtained based on P1(px1,py1) and P2(px2,py2) The slope of the line can be obtained based on the (pdx, pdy) coordinates. The slope of the two straight lines and The angle between (ie, the turning angle of the vehicle) can be calculated as shown in Equation 4 below.

[0067] Equation 4 :

[0068] a=tan(π / 2+θ),θ=tan -1 ((py2-py1) / (px2-px1))

[0069] In equation 4, a represents the straight line The slope of θ represents two straight lines. and The angle between (i.e. the turning angle of the vehicle).

[0070] Because the straight line The equation can be shown as Equation 5 and the straight line The equation of can be shown as Equation 6, so two straight lines can be obtained as shown in Equation 7 and The intersection point (s, t).

[0071] Equation 5:

[0072] y=a*x+pdy-a*pdx

[0073] Equation 6 :

[0074] x=d

[0075] Equation 7 :

[0076] (s, t) = (d, a*d + pdy - a*pdx)

[0077] By solving Equation 8 to determine the optimal solution for d in the range δ≤d≤σ (δ<0,σ>0), it can be determined whether the length from the intersection point (s, t) to each of the two points (d, 0) and (pdx, pdy) has an equal value. Here, δ and σ may be limited by the maximum steering angle of the tire and the vehicle specifications.

[0078] Equation 8 :

[0079] d 2 -2d(pdx+a*pdy)+pdx 2 -pdy 2 +2a*pdx*pdy=0

[0080] By substituting the obtained value d into Equation 7, the turning center of the vehicle can be calculated.

[0081] According to another embodiment of the present disclosure, a process of calculating a turning center when a user steers with a steering wheel by himself is as follows.

[0082] In the case of a vehicle with a rear wheel steering system, the turning center of the vehicle and the one-step vehicle movement time t adjusted based on the angle of the steering wheel input by the user, the vehicle speed, etc. may be pre-stored in a lookup table (LUT) for management. Here, the one-step vehicle movement time t refers to a time period for moving the vehicle based on the steering angle of each wheel and the power frequency. Therefore, the center point of turning corresponding to the angle of the steering wheel input by the user and the speed of the vehicle may be calculated based on the pre-stored lookup table.

[0083] In the case of a vehicle without a rear wheel steering system (i.e., in the case of a vehicle in which only the front wheels are steerable), the turning center of the vehicle and the one-step vehicle movement time t adjusted based on the steering wheel angle, vehicle speed, etc. input by the user may be pre-stored in a lookup table (LUT) for management. Here, the one-step vehicle movement time t refers to a time period for moving the vehicle based on the steering angle and power frequency of each wheel. In this case, as described above with reference to Figure 2B As mentioned above, the turning center of the vehicle may be on the axis of the rear wheels. Figure 7 The turning center of the vehicle is obtained as shown in Equation 9.

[0084] Equation 9 :

[0085]

[0086] In Equation 9, k represents a proportional constant, τ represents an angle of a steering wheel input by a user, and m represents a wheelbase, and center point of turning represents a turning center point.

[0087] The steering angle calculation unit 320 may calculate the steering angle of each wheel based on the turning center point of the vehicle. In addition, the steering angle calculation unit 320 may calculate the turning radius of the vehicle and the turning radius of each wheel based on the turning center point of the vehicle. The process of calculating the steering angle will refer to Figure 8 Give a description.

[0088] The steering angle and turning radius of each wheel may be calculated based on the turning center of the vehicle and the position of each wheel.

[0089] The steering angle of each wheel can be obtained as shown in Equation 10.

[0090] Equation 10 :

[0091]

[0092] In equation 10, represents the steering angle of each wheel, (x', y') represents the position coordinates of each wheel, and (s, t) represents the coordinates of the turning center of the vehicle.

[0093] The turning radius R of the vehicle can be obtained as shown in Equation 11 vehicle .

[0094] Equation 11 :

[0095]

[0096] The turning radius R of each wheel can be obtained as shown in Equation 12: tire .

[0097] Equation 12 :

[0098]

[0099] At the same time, the range of selection of P1 (px1, py1) and P2 (px2, py2) is limited by the maximum steering angle of each wheel and the vehicle specifications. Therefore, equations 3 to 11 can be used to pre-calculate the turning center point of the vehicle corresponding to the optional points P1 and P2, the turning radius of the vehicle, the steering angle of each wheel, and the turning radius of each wheel so as to save their data in a lookup table (LUT).

[0100] The power frequency calculation unit 330 may calculate the power frequency of each wheel based on the turning radius of each wheel and the required speed of each wheel. Here, the required speed refers to the minimum value of the limit speed or the speed set by the user.

[0101] First, the limit speed refers to the maximum speed at which rollover does not occur based on the turning radius of the vehicle. When the vehicle turns, if the sum of the moment due to centrifugal force and the moment due to gravity is less than 0, rollover may occur. Therefore, the limit speed based on the turning radius of the vehicle obtained by the steering angle calculation unit 320 can be calculated using Equation 13.

[0102] Equation 13:

[0103]

[0104] In Equation 13, ∑ represents the sum of the moments, Z represents the height from the ground to the center of the vehicle, w represents the wheelbase of the vehicle, m represents the weight of the vehicle, g represents the gravitational acceleration, and R vehicle represents the turning radius of the vehicle, and V RolloverIndicates the maximum speed at which the vehicle does not roll over.

[0105] The angular velocity of each wheel can be equal to the angular velocity of the vehicle (ω). The velocity V of each wheel tire The turning radius R of each wheel tire In other words, the speed of each wheel can be determined by the turning radius of each wheel and the angular velocity of the vehicle, as shown in Equation 14.

[0106] Equation 14:

[0107]

[0108] In Equation 14, V represents the desired speed.

[0109] As shown in Equation 15, the radius of the tire r tire and each wheel speed V tire Get the power frequency f of each wheel tire .

[0110] Equation 15:

[0111] f tire =V tire / (r tire *2π), V tire =r tire *ω=r tire *2πf tire

[0112] The suspension height calculation unit 340 may calculate the height of the vehicle suspension based on the radius of the turn and the desired speed of the vehicle. In the case of an air suspension, the ride comfort may be improved by adjusting the height of the left / right suspension. The value of the force applied to the driver may correspond to the sum (Fa+Fg) of the force Fa applied by the centripetal acceleration and the force Fg applied by the gravitational acceleration. When the vehicle rolls at θ, the driver may not feel the centripetal acceleration, such as Fig. 9 and Equation 16.

[0113] Equation 16 :

[0114]

[0115] In Equation 16, h represents the height of the suspension of the vehicle to be adjusted, w represents the wheelbase of the vehicle, and θ represents the vehicle angle that can be changed by the air suspension of the vehicle.

[0116] Since the turning radius R of the vehicle has been calculated vehicle and the desired speed V, the height h of the vehicle's suspension can therefore be obtained by multiplying by the appropriate proportionality constant l, as shown in Equation 17.

[0117] Equation 17:

[0118]

[0119] During a time period (hereinafter referred to as a "movement period") during which the vehicle is moved based on the steering angle of each wheel and the power frequency of each wheel, the output unit 350 may output information about the steering angle of each wheel. The data is output to the corresponding steering device, and the power frequency f at each wheel is tire The power is applied to the corresponding in-wheel motor, and data on the height h of the suspension is output to the device for controlling the suspension.

[0120] According to an embodiment of the present disclosure, under the condition of autonomous driving in which the driving trajectory to be followed by the vehicle is given as a set of point coordinates, the moving time period can be calculated based on the turning angle of the vehicle, the turning radius of the vehicle, and the speed of the vehicle. For example, the time period t can be obtained as shown in Equation 18.

[0121] Equation 18:

[0122]

[0123] In Equation 18, θ represents the turning angle of the vehicle obtained by Equation 4.

[0124] According to another embodiment of the present disclosure, under the condition that the user steers the vehicle with the steering wheel himself, a moving time period corresponding to the data about the steering wheel angle input by the user and the speed of the vehicle can be obtained based on a pre-stored lookup table.

[0125] The inverter 360 may convert the DC power of the battery into AC power and supply it to the in-wheel motor. The inverter 360 may supply the AC power converted based on the power frequency of each wheel to the corresponding in-wheel motor.

[0126] Fig.10 is a flowchart illustrating a control process for each scenario according to an embodiment of the present disclosure.

[0127] See also Fig.10 , at S1010 , it may be determined whether the vehicle is operating in an automatic driving mode.

[0128] When it is determined that the vehicle is operating in autonomous driving mode, at S1020, local coordinates can be set based on the current position of the vehicle, a target position can be selected from a given tracking trajectory and converted into local coordinates, and the coordinates of the vehicle's turning center can be calculated based on the center of the vehicle and the direction the vehicle is traveling at the target position.

[0129] When it is determined that the vehicle is not operating in the automatic driving mode, at step S1030, it may be determined whether the vehicle has a rear wheel steering system, that is, whether the front wheels are steerable and the rear wheels are not steerable.

[0130] When it is determined that the vehicle does not have a rear wheel steering system (Yes at S1030 ), at step S1040 , the coordinates of the turning center of the vehicle may be calculated based on the angle of the steering wheel input by the user.

[0131] When it is determined that the vehicle has a rear wheel steering system (No at S1030 ), at step S1050 , the coordinates of the rotation center of the vehicle corresponding to the angle of the steering wheel input by the user may be obtained based on a lookup table.

[0132] After calculating or obtaining the coordinates of the turning center of the vehicle, S1060 may be performed. That is, the steering angle of each wheel and the turning radius of each wheel may be determined based on the coordinates of the turning center of the vehicle. The power frequency may be determined based on the turning radius of each wheel and the required speed. The moving time period t may be calculated or obtained by referring to a pre-stored lookup table. The suspension height for compensating for the centripetal force may be calculated. The vehicle may be operated by providing data on the steering angle of each wheel and the height of the device for controlling the suspension to the device for steering the wheel, and supplying power at the power frequency of each wheel to the motors in all wheels for the number of seconds of the moving time period t.

[0133] After determining whether the driving of the vehicle is ended at S1070 , S1010 may be performed while the vehicle is still being driven, and the entire process may be ended when the driving of the vehicle is ended.

[0134] Fig.11 is a flowchart illustrating a process of controlling the steering and speed of each wheel of a vehicle based on a turning center according to an embodiment of the present disclosure.

[0135] See also Fig.11 At S1110, the turning center point of the vehicle may be calculated based on the information about the driving of the vehicle. The information about the driving of the vehicle may include the driving track to be followed by the vehicle or the angle of the steering wheel input by the user.

[0136] At S1120 , a turning radius of the vehicle, a steering angle of each wheel, and a turning radius of each wheel may be calculated based on the turning center point.

[0137] At S1130 , the power frequency of each wheel may be calculated based on the turning radius and the required speed of each wheel.

[0138] At S1140 , the height of the suspension may be calculated based on the turning radius and the required speed of the vehicle.

[0139] During the moving time period, at S1150, the steering angle of each wheel may be output to the corresponding steering device, power at the power frequency of each wheel may be applied to the corresponding in-wheel motor, and the height of the suspension may be output to a device for controlling the suspension.

[0140] The above process can be repeated while driving the vehicle.

[0141] Each component of the device or method according to an embodiment of the present disclosure can be implemented by hardware, software, or a combination of hardware and software. In addition, the function of each component can be implemented by software, and the microprocessor can be implemented to execute the function of the software corresponding to each component.

[0142] Various specific implementations of the systems and techniques described herein may be implemented by digital electronic circuits, integrated circuits, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), computer hardware, firmware, software, and / or combinations thereof. These various specific implementations may include implementation in one or more computer programs that may be executed on a programmable system. A programmable system includes at least one programmable processor (which may be a special purpose processor or a general purpose processor) coupled to receive data and instructions from and send data and instructions to a storage system, at least one input device, and at least one output device. A computer program (also referred to as a program, software, software application, or code) includes instructions for a programmable processor and is stored on a "computer-readable recording medium."

[0143] Computer-readable storage media include various storage devices that store data that can be read by a computer system. Computer-readable storage media may include non-volatile or non-transitory media such as ROM, CD-ROM, magnetic tape, floppy disk, memory card, hard disk, magneto-optical disk, storage device, and also include transient media such as data transmission media. In addition, computer-readable storage media may be distributed in computer systems connected via a network, and computer-readable codes may be stored and executed in a distributed manner.

[0144] In the flowcharts in this specification, each process is described to occur sequentially, but this is only an example of the technology of the embodiments of the present disclosure. In other words, a person skilled in the art to which the embodiments of the present disclosure belong can make various modifications and variations by changing the order described in the flowcharts in this specification or by performing one or more processes in parallel within the basic features of the embodiments of the present disclosure, so the flowcharts in this specification are not limited to the time series order.

[0145] Although exemplary embodiments of the present disclosure are described for illustrative purposes, it will be appreciated by those skilled in the art that various modifications, additions, and substitutions may be made without departing from the concept and scope of the claimed invention. Therefore, exemplary embodiments of the present disclosure have been described for the sake of brevity and clarity. The scope of the technical ideas of the embodiments of the present disclosure is not limited by the illustrations. Therefore, it will be appreciated by those of ordinary skill that the scope of the claimed invention is not limited by the embodiments explicitly described above, but by the claims and their equivalents.

Claims

1. A method for controlling the steering and speed of each wheel of a vehicle based on a turning center, the method comprising the following steps: Calculating a turning center point of the vehicle based on driving information of the vehicle; Calculating the turning radius of the vehicle, the steering angle of each wheel, and the turning radius of each wheel based on the turning center point; calculating a power frequency for each wheel based on the turning radius and the desired speed; as well as During a period of moving the vehicle based on the steering angle of each wheel and the power frequency of each wheel, the steering angle of each wheel is output to the corresponding steering device, and power is applied to the corresponding in-wheel motor at the power frequency of each wheel. 2 . The method according to claim 1 , wherein the driving information of the vehicle includes a driving trajectory to be followed by the vehicle or an angle of a steering wheel input by a user.

3. The method according to claim 2, wherein calculating the turning center point comprises: setting a local coordinate system using the current position of the vehicle as a reference point; Selecting a target position to which the vehicle will move from the driving trajectory, and converting the target position into the local coordinate system; as well as The turning center point of the vehicle is calculated based on the current position and the target position.

4. The method according to claim 3, wherein: The time period for moving the vehicle based on the steering angle of each wheel and the power frequency of each wheel is calculated based on the turning angle between the current position and the target position, the turning radius of the vehicle, and the speed of the vehicle.

5. The method according to claim 2, wherein when calculating the turning center point, the turning center point of the vehicle is calculated based on a lookup table, and the turning center point corresponding to the steering wheel angle input by the user and the speed of the vehicle is pre-stored in the lookup table.

6. The method according to claim 5, wherein: The time period for moving the vehicle based on the steering angle of each wheel and the power frequency of each wheel is obtained based on the lookup table as a time period corresponding to the angle of the steering wheel input by the user and the speed of the vehicle. 7 . The method according to claim 1 , wherein in calculating the turning radius of the vehicle, the turning radius of the vehicle is calculated based on the turning center point and a center point of the vehicle.

8. The method according to claim 1, wherein in calculating the steering angle of each wheel and the turning radius of each wheel, the steering angle of each wheel and the turning radius of each wheel are calculated based on the turning center point and the position of each wheel of the vehicle. 9 . The method according to claim 1 , wherein the required speed is a minimum value between a limit speed at which the turning radius of the vehicle does not roll over and a speed set by a user.

10. The method of claim 1, wherein calculating the power frequency of each wheel comprises: calculating an angular velocity of the vehicle based on a turning radius of the vehicle and a speed of the vehicle; calculating a speed of each wheel based on an angular velocity of the vehicle and a turning radius of each wheel; as well as The power frequency of each wheel is calculated based on the speed of each wheel and the radius of each wheel.

11. The method according to claim 1, further comprising the steps of: calculating a height of a suspension of the vehicle based on a turning radius and a desired speed of the vehicle; as well as During the period of time of moving the vehicle, the calculated height of the suspension is output to a corresponding device for controlling the suspension.

12. An apparatus for controlling the steering and speed of each wheel of a vehicle based on a turning center, the apparatus comprising: an in-wheel motor mounted on each wheel of said vehicle; a steering device for performing steering of each wheel of said vehicle; as well as A controller for controlling the steering angle and speed of each wheel of the vehicle, wherein the controller comprises: one or more processors; and A storage device storing a program to be executed by the one or more processors, the program including instructions for: Calculating a turning center point of the vehicle based on driving information of the vehicle; Calculating the turning radius of the vehicle, the steering angle of each wheel, and the turning radius of each wheel based on the turning center point; calculating the power frequency of each wheel based on the turning radius and the required speed of each wheel; and During a period of moving the vehicle based on the steering angle of each wheel and the power frequency of each wheel, the steering angle of each wheel is output to the corresponding steering device, and power is applied to the corresponding in-wheel motor at the power frequency of each wheel. 13 . The device according to claim 12 , wherein the driving information of the vehicle includes a driving track to be followed by the vehicle or an angle of a steering wheel input by a user.

14. The apparatus of claim 13, wherein the program further comprises instructions for: setting a local coordinate system using a current position of the vehicle as a reference point, selecting a target position to which the vehicle will move from the driving trajectory, converting the target position into the local coordinate system, and calculating the turning center point of the vehicle based on the current position and the target position.

15. The device according to claim 14, wherein: The time period for moving the vehicle based on the steering angle of each wheel and the power frequency of each wheel is calculated based on the turning angle between the current position and the target position, the turning radius of the vehicle, and the speed of the vehicle.

16. The apparatus of claim 13, wherein the program further comprises instructions for calculating a turning center point of the vehicle based on a lookup table, in which turning center points corresponding to the steering wheel angle input by the user and the speed of the vehicle are pre-stored.

17. The device according to claim 16, wherein: The time period for moving the vehicle based on the steering angle of each wheel and the power frequency of each wheel is obtained based on the lookup table as a time period corresponding to the angle of the steering wheel and the speed of the vehicle input by the user.

18. The apparatus according to claim 12, further comprising: Device for controlling a suspension to adjust the height of the suspension of the vehicle, wherein the program further includes instructions for calculating the height of the suspension of the vehicle based on a turning radius and a required speed of the vehicle, and outputting the height of the suspension of the vehicle to the device for controlling the suspension.

19. The device according to claim 12, wherein: The required speed is a minimum value between a limit speed at which the vehicle does not roll over based on a turning radius and a speed set by a user.

20. The apparatus of claim 12, wherein the program further comprises instructions for calculating the power frequency of each wheel by: calculating an angular velocity of the vehicle based on a turning radius of the vehicle and a speed of the vehicle; calculating a speed of each wheel based on an angular velocity of the vehicle and the turning radius of each wheel; and The power frequency of each wheel is calculated based on the speed of each wheel and the radius of each wheel.

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