Electronic differential control method and system thereof

Abstract

The present invention provides an electronic differential control method and system thereof comprising: a steering input unit; a gainer; a conversion unit; an accelerator pedal input unit; a calculation unit; a yaw tracking unit; a wheel speed control unit; and a drive wheelset; wherein the steering input unit provides a torque demand command; the accelerator pedal input unit provides a torque demand command; the conversion unit generates a reference speed command ; the gainer generates a yaw angular speed command ; the calculation unit calculates and generates a radius of rotation information; and the yaw tracking unit calculates and generates a reference wheel speed command . The yaw tracking unit generates a reference wheel speed command based on the rotational radius information and the reference vehicle speed command; and the wheel speed control unit controls the drive wheelset based on the reference wheel speed command. When the steering command is detected to exceed the preset threshold value, the electronic differential system will automatically intervene and distribute the wheel speed accordingly, realizing the improvement of steering performance and driving stability.

Description

Technical Field

[0001] This invention relates to an electronic differential control method and system, and more particularly to a method and system capable of adjusting the drive wheels of a vehicle through steering input and accelerator pedal input. Prior Technology

[0002] With global environmental problems becoming increasingly serious, reducing the environmental impact of transportation has become an important goal for governments and businesses worldwide. Hybrid vehicles and pure electric vehicles, due to their ability to reduce emissions and improve energy efficiency, have become important means to achieve this goal.

[0003] Whether in passenger cars or buses, electric motors are gradually replacing engines as the main source of vehicle power transmission. Due to the flexibility of electric drive motor configuration, multiple drive motors can be equipped on a single vehicle, mainly divided into two types: centralized drive and independent wheel drive. Since the torque and speed required by each wheel are different when the vehicle is cornering, centralized drive requires a differential to distribute torque, but efficiency loss occurs after power is transmitted multiple times.

[0004] To reduce efficiency losses caused by the differential, direct drive can be implemented using independent wheel drive, reducing transmission losses. This design allows for independent drive control of the drive wheels and makes the control strategy more flexible. When the vehicle is turning, the controller can distribute the drive / braking torque to each wheel to achieve electronic differential function.

[0005] Electronic Differential Systems (EDS) play a crucial role in electric vehicles. For electric vehicles equipped with independent wheel drive, differential drive or differential braking can be used to generate the correct yaw torque. The electronic differential function is achieved by distributing the drive / braking torque of the motors on both sides of the wheel.

[0006] Conventional technology typically uses vehicle speed and steering angle to calculate the ideal yaw rate of the vehicle at the current time, and combines Ackerman geometry to calculate the reference wheel speed of the inner and outer drive wheels for speed control. It also has dynamic characteristics of yaw rate with high gain at low speed and low gain at high speed, which increases the vehicle's agility at low speed and stability at high speed.

[0007] Electronic differential control methods do not use yaw rate sensors, so they cannot use the feedback signal from this sensor to correct the yaw control command. They are open-loop control of yaw rate. Although the electronic differential effect can be achieved through wheel speed control, when the system is subjected to disturbance input, the lack of feedback signal to correct the control command makes it impossible to ensure a good yaw rate following effect.

[0008] To address this shortcoming, it is conventional to use a yaw rate sensor for closed-loop direct yaw moment control (DYC). This method primarily works by tracking the ideal yaw rate and limiting the vehicle's sideslip angle, enabling the vehicle to maintain stable driving while avoiding loss of lateral stability and skidding. This is one of the most common stability control methods currently available.

[0009] However, regardless of whether it is front-wheel drive or four-wheel drive, as long as torque vectoring control is applied to the front axle, the imbalance of longitudinal forces in the front wheels will generate interfering torque on the steering wheel, resulting in a poor driving experience and increasing the difficulty of driving.

[0010] Therefore, this paper provides a full-speed-range electronic differential control system based on a kinematic model. By combining kinematic geometry to consider the effects of centrifugal force and sideslip at high speeds, it can realize electronic differential control across the entire speed range. Moreover, all the necessary information can be obtained through actual vehicle sensors. This electronic differential control method and system has high practical application feasibility and is the problem that those skilled in the art wish to solve. Summary of the Invention

[0011] One objective of this invention is to provide an electronic differential control method that uses a computing unit to calculate information obtained from vehicle sensors using a kinematic model, and then combines this with considerations of centrifugal force and sideslip at high speeds to achieve full-speed-range electronic differential control.

[0012] To achieve the aforementioned objectives, this invention provides an electronic differential control method applied to a vehicle controlling a drive wheel assembly during cornering via a steering input unit, an accelerator pedal input unit, and a wheel speed control unit. The method includes: a calculation module receiving a steering command from the steering input unit and a torque demand command from the accelerator pedal input unit; the calculation module generating a reference vehicle speed command based on the torque demand command, and generating a yaw rate command based on the reference vehicle speed command and the steering command; calculating and generating rotation radius information based on the steering command, the reference vehicle speed command, and the yaw rate command; generating a reference wheel speed command based on the steering command, the rotation radius information, and the reference vehicle speed command, and transmitting it to the wheel speed control unit; and the wheel speed control unit controlling the drive wheel assembly based on the reference wheel speed command. This provides an electronic differential control method that replaces the previous method of adjusting the vehicle solely through a differential, offering better differential adjustment for various situations.

[0013] The present invention provides an embodiment in which the calculation module generates a reference vehicle speed command based on the torque demand command, generates a yaw rate command based on the reference vehicle speed command and the steering command, calculates and generates rotation radius information based on the steering command, the reference vehicle speed command and the yaw rate command, and generates a reference wheel speed command based on the steering command, the reference vehicle speed command and the yaw rate command, and transmits it to the wheel speed control unit. The embodiment further includes the following steps: a conversion unit generates a reference vehicle speed command based on the torque demand command; a gainer receives and generates a yaw rate command based on the reference vehicle speed command and the steering command; a calculation unit receives and calculates and generates rotation radius information based on the steering command, the reference vehicle speed command and the yaw rate command; and a yaw tracking unit receives and generates a reference wheel speed command based on the steering command, the rotation radius information and the reference vehicle speed command and transmits it to the wheel speed control unit.

[0014] The present invention provides an embodiment in which, in the steps of the calculation module generating a reference vehicle speed command based on the torque demand command, generating a yaw rate command based on the reference vehicle speed command and the steering command, calculating and generating rotation radius information based on the steering command, the reference vehicle speed command and the yaw rate command, and generating a reference wheel speed command based on the steering command, the rotation radius information and the reference vehicle speed command and transmitting it to the wheel speed control unit, the rotation radius information further includes rotation radius information of a left front drive wheel, rotation radius information of a left rear drive wheel, rotation radius information of a right front drive wheel and rotation radius information of a right rear drive wheel.

[0015] The present invention provides an embodiment in which, after a yaw tracking unit receives and generates a reference wheel speed command based on the steering command, the rotation radius information and the reference vehicle speed command and transmits it to the wheel speed control unit, the invention further includes the step of: a first sensing device sensing feedback information of one of the drive wheel sets and transmitting the feedback information back to the wheel speed control unit.

[0016] The present invention provides an embodiment in which, after a calculation unit receives and calculates and generates a rotation radius information based on the steering command, the reference vehicle speed command and the yaw rate command, the invention further includes the step of: a second sensing device sensing yaw rate feedback information of a vehicle and transmitting the yaw rate feedback information back to the yaw tracking unit.

[0017] Another objective of this invention is to provide an electronic differential control system that uses a computing unit to calculate information obtained from real vehicle sensors using a kinematic model, and combines kinematic geometry to consider the effects of centrifugal force and sideslip at high speeds, thereby enabling electronic differential control across the entire speed range.

[0018] To achieve the aforementioned objectives, the present invention provides an electronic differential control system, which is applied to a vehicle to control a drive wheel assembly during cornering via a steering input unit, an accelerator pedal input unit, and a wheel speed control unit. The system includes: the steering input unit; a calculation module connected to the steering input unit; the accelerator pedal input unit connected to the calculation module; the wheel speed control unit electrically connected to the calculation module; and the drive wheel assembly electrically connected to the wheel speed control unit. The calculation module receives a steering command from the steering input unit and a torque demand command from the accelerator pedal input unit. The calculation module generates a reference vehicle speed command based on the torque demand command, and generates a yaw rate command based on the reference vehicle speed command and the steering command. It also calculates and generates a rotation radius information based on the steering command, the reference vehicle speed command, and the yaw rate command. Finally, it generates a reference wheel speed command based on the steering command, the rotation radius information, and the reference vehicle speed command and transmits it to the wheel speed control unit. The wheel speed control unit controls the drive wheel assembly based on the reference wheel speed command, thereby providing an electronic differential control system that replaces the previous method of adjusting the vehicle solely through the differential, thus allowing for better adjustment of the vehicle's differential speed according to various situations.

[0019] The present invention provides an embodiment in which the computing module further includes: a gainer electrically connected to the steering input unit; a conversion unit electrically connected to the gainer; an accelerator pedal input unit electrically connected to the conversion unit; a computing unit electrically connected to the gainer, the conversion unit, and the steering input unit; and a yaw tracking unit electrically connected to the steering input unit, the computing unit, the conversion unit, and the wheel speed control unit; wherein the conversion unit generates a reference vehicle speed command based on the torque demand command; the gainer receives and generates a yaw rate command based on the reference vehicle speed command and the steering command; the computing unit receives and calculates and generates rotation radius information based on the steering command, the reference vehicle speed command, and the yaw rate command; and the yaw tracking unit receives and generates a reference wheel speed command based on the steering command, the rotation radius information, and the reference vehicle speed command and transmits it to the wheel speed control unit.

[0020] The present invention provides an embodiment in which the rotation radius information further includes rotation radius information of a left front drive wheel, rotation radius information of a left rear drive wheel, rotation radius information of a right front drive wheel, and rotation radius information of a right rear drive wheel.

[0021] The present invention provides an embodiment in which the drive wheel assembly is further disposed on the vehicle, the vehicle further comprising: a first sensing device disposed on the drive wheel assembly, the first sensing device being used to sense feedback information of the drive wheel assembly; and a second sensing device disposed on the vehicle, the second sensing device being used to sense yaw rate feedback information of the vehicle; wherein the first sensing device senses the feedback information of the drive wheel assembly and transmits the feedback information back to the wheel speed control unit, and the second sensing device senses the yaw rate feedback information of the vehicle and transmits the yaw rate feedback information back to the yaw tracking unit.

[0022] Therefore, an electronic differential control method and system that can adjust the differential speed of a vehicle according to different situations and can be used across the entire speed range is provided to address the problem that those skilled in the art wish to solve. Simple Explanation of the Diagram

[0023] Figure 1: It is a flowchart of the electronic differential control method of the present invention; Figure 2: It is a schematic diagram of the electronic differential control system of the present invention; Figure 3: It is a flowchart of the electronic differential control method of the present invention; Figure 4A: It is a schematic diagram of the steps of the electronic differential control method of the present invention; Figure 4B: This is a schematic diagram of the steps of the electronic differential control method of the present invention; Figure 5: This is a schematic diagram of the vehicle dynamics model of the present invention; Figure 6: This is a schematic diagram of the yaw rate gain of the present invention; Figure 7: It is a schematic diagram of the steps of the electronic differential control method of the present invention; Figure 8: This is a schematic diagram of the motion steering geometry of the present invention; Figure 9: It is a flowchart of the electronic differential control method of the present invention; and Figure 10: It is a schematic diagram of the electronic differential control system of the present invention. Implementation

[0024] To enable your review committee to gain a better understanding of the features and effects achieved by this invention, preferred embodiments and detailed descriptions are provided below:

[0025] Since most current systems are divided into low-speed and medium-to-high-speed components, it is common practice to use Ackerman geometry based on kinematic models for differential design in low-speed systems, while to use dynamic models for torque vector research in medium-to-high-speed systems. Different models are used for calculations at different vehicle speeds. Although differential control systems based on dynamic models can more accurately reflect the actual operating state of the vehicle, they mostly involve complex calculations and models with high degrees of freedom, and the control effect is not obvious at low speeds. Therefore, different models are used for calculations at different vehicle speeds.

[0026] This invention combines motion geometry to consider the effects of centrifugal force and sideslip at high speeds, thereby realizing a full-speed-range electronic differential control system. All the necessary information can be obtained from the vehicle's sensors. At the same time, this invention integrates an electric power steering control system and designs a simple feedforward compensation control method. By using the electric power steering system to counteract the interference torque generated by steering, the driver's steering feel is restored. This allows the driver to more easily control the vehicle's steering behavior without affecting the steering feel.

[0027] The invention will be described in detail below by way of the drawings illustrating various embodiments thereof. However, the concept of the invention may be embodied in many different forms and should not be construed as being limited to the exemplary embodiments set forth herein.

[0028] First, please refer to Figure 1, which is a flowchart of the electronic differential control method of the present invention. As shown in the figure, the steps of an electronic differential control method of the present invention will then be described in detail:

[0029] Step S10: The calculation module receives steering commands from the steering input unit and torque demand commands from the accelerator pedal input unit;

[0030] Step S20: The calculation module generates a reference vehicle speed command based on the torque demand command, and generates a yaw rate command based on the reference vehicle speed command and the steering command. It also calculates and generates rotation radius information based on the steering command, reference vehicle speed command, and yaw rate command, and generates a reference wheel speed command based on the steering command, rotation radius information, and reference vehicle speed command, and transmits it to the wheel speed control unit.

[0031] Step S30: The wheel speed control unit controls the drive wheel assembly according to the reference wheel speed command.

[0032] Next, please refer to Figure 2, which is a schematic diagram of the electronic differential control system of the present invention. As shown in the figure, an electronic differential control system 1 of the present invention will be described in detail, which includes: a steering input unit 10; a gainer 20 electrically connected to the steering input unit 10; a calculation module 5, which includes: a conversion unit 30 electrically connected to the gainer 20; an accelerator pedal input unit 40 electrically connected to the conversion unit 30; a calculation unit 50 electrically connected to the gainer 20, the conversion unit 30, and the steering input unit 10; a yaw tracking unit 60 electrically connected to the steering input unit 10, the calculation unit 50, and the conversion unit 30; a wheel speed control unit 70 electrically connected to the yaw tracking unit 60; and a drive wheel set 80 electrically connected to the wheel speed control unit 70.

[0033] The following details each step. In step S10, a calculation module 5 receives a steering command from the steering input unit 10 and a torque demand command from the accelerator pedal input unit 40. In this embodiment, the steering input unit 10 is a steering wheel of a vehicle, but is not limited thereto. The steering input unit 10 can be any unit that can control the steering of the vehicle's drive wheels. The accelerator pedal input unit 40 is an acceleration control device of a vehicle, but is not limited thereto. The accelerator pedal input unit 40 can be any unit that can control the forward movement of the vehicle's drive wheels.

[0034] Step S20 further includes steps S22-S28. Please refer to Figure 3, which is a flowchart of the electronic differential control method of the present invention, and is explained as follows:

[0035] Step S22: The conversion unit generates a reference vehicle speed command based on the torque demand command and transmits it to the gain unit, the calculation unit, and the yaw tracking unit;

[0036] Step S24: The gainer generates a yaw rate command based on the reference vehicle speed command and the steering command, and transmits it to the calculation unit;

[0037] Step S26: The calculation unit calculates and generates rotation radius information based on the steering command, reference vehicle speed command, and yaw rate command, and transmits it to the yaw tracking unit;

[0038] Step S28: The yaw tracking unit generates a reference wheel speed command based on the steering command, turning radius information, and reference vehicle speed command, and transmits it to the wheel speed control unit;

[0039] Please refer to Figures 3, 4A, and 4B. Figure 4A is a schematic diagram of the steps of the electronic differential control method of the present invention, and Figure 4B is a schematic diagram of the steps of the electronic differential control method of the present invention. As shown in the figures, in step S22, the conversion unit generates a reference vehicle speed command 32 based on the torque demand command 42. In this embodiment, the function of the conversion unit 30 is to convert the torque demand command 42 provided by the accelerator pedal input unit 40 into the digital reference vehicle speed command 32, that is, to provide the current reference vehicle speed of the vehicle for subsequent calculation by the gain unit 20, the calculation unit 50, and the yaw tracking unit 60.

[0040] Referring again to Figures 3, 4A, and 4B, as shown, in step S24, the gainer 20 receives and generates a yaw rate command 22 based on the reference vehicle speed command 32 and the steering command 12. In this embodiment, the function of the gainer 20 is to calculate and generate the yaw rate command 22 based on the reference vehicle speed command 32 and the steering command 12.

[0041] Continuing from the above, please refer to Figure 5, which is a schematic diagram of the vehicle dynamics model of the present invention. The calculation method of the yaw rate command 22 is shown in Equation (I) and Equation (II) below. The calculation here treats the vehicle as a front-wheel drive four-wheel vehicle. Formula (1) Formula (II)

[0042] in, For steady-state yaw rate gain, For reference vehicle speed, For vehicle mass, The reference command for yaw rate. Wheelbase Here, represents the front wheel tire steering angle, and represents the understeer coefficient. and The equivalent steering stiffness of the front and rear axles. The distance from the center of gravity to the front axle. The distance from the center of gravity to the rear axle is used to obtain the yaw rate command 22 required by the driver through the reference vehicle speed command 32 and the steering command 12.

[0043] Continuing from the above, please refer to Figure 6, which is a schematic diagram of the yaw rate gain of the present invention. As shown in the figure, it illustrates the yaw rate gain of a general vehicle and the system of the present invention at different speeds. The present invention enables the vehicle to have a more sensitive dynamic response at low speeds, and at high speeds, it can also prevent the vehicle from overturning or losing control due to excessively high yaw rates.

[0044] Continuing from the above, when the vehicle is cornering, it will travel according to the required yaw rate command 22. The calculation formula for its yaw rate gain is as described in Equation (I), and its understeer coefficient is also included. Designed with adjustable coefficients.

[0045] Please refer to Figures 3, 4 and 7. Figure 7 is a schematic diagram of the steps of the electronic differential control method of the present invention. As shown in the figure, in step S26, the calculation unit 50 receives and calculates and generates a rotation radius information 52 based on the steering command 12, the reference vehicle speed command 32 and the yaw rate command 22.

[0046] Next, please refer to Figure 8, which is a schematic diagram of the motion steering geometry of the present invention, as shown in the figure, wherein, For the tire radius, and are the reference wheel speeds for the left and right front wheels, respectively, and is the rotation center. Let be the center of rotation after being affected by centrifugal force, and let be the speed of the front wheels of the vehicle model. , The speeds of the left and right front wheels are respectively. The shortest distance from the turning center to the car. The turning radius of the left front wheel. Where is the turning radius of the right front wheel, is the wheelbase, and is the track width. For line segments The length of.

[0047] The vehicle will circle around the point during the turn. In this embodiment, the rotation is known to have a velocity direction perpendicular to the radius of rotation and at an angle to the longitudinal direction of the vehicle body. Through the two perspectives mentioned above, we can deduce that ∠ The current angle of 𝐴𝐸 is And because ∠ Since α is a right angle, we can use the fact that the sum of the interior angles of a triangle is 1 / 2. , to obtain ∠𝐴 𝐸 for The actual speed direction of the rear wheels is at an angle to the direction of the vehicle body. line segment Since the equivalent radius of rotation of the rear wheel of the model is perpendicular to its velocity direction, the other angles ∠ can be determined. 𝐵𝐸 for , and because of ∠ EB is a right angle, ∠B E is the ∠ in ∆O'BE the complementary angle of BE, so ∠B can be obtained E is .

[0048] Through the above description, all the angles in ∆ AE and ∆ BE of the two triangles can be calculated. In order to obtain the equivalent radius of gyration of the front and rear wheels of the model and then obtain the reference wheel speeds of each driving wheel, first, the relevant variables required for the calculation process need to be derived from ∆[[ID=6z]] AB and , in ∆ In 𝐴𝐸, ∠𝐴 can be used. To express using the tangent of 𝐸 and The relationship between them is calculated as shown in equation (iii), where ∆ ∠❐� can be used in 𝐵𝐸 To represent the tangent of 𝐸 and The relationship between them is calculated as shown in equation (iv). Can be determined by side length What was obtained. Formula (3) Formula (IV)

[0049] in and Let be the tire side slip angle of the front and rear wheels of the model. Their relationship can be expressed by the following formulas (5) and (6). Formula (5) Formula (VI)

[0050] in To determine the lateral velocity of the vehicle, we solve for the unknowns using equations (v) and (vi) above, and derive the required variables. as well as The expressions for are as follows: (VII) and (VIII). Formula (VII) Formula (8)

[0051] Continuing from the above, we can calculate the turning radius of the left and right drive wheels under the current cornering requirements using kinematic geometry. It is known that during a turn, the turning radius of the inner and outer wheels is affected by the steering angle; the projected distance of the inner wheel's center of rotation will decrease by half the wheelbase. The horizontal projection distance of the outer wheel's rotation center will increase by half the wheelbase. If the vehicle is front-wheel drive, the equations are as follows (9A) and (10A); if the vehicle is rear-wheel drive, the equations are as follows (9B) and (10B). Formula (9A) Formula (+A) Formula (9B) Formula (10)

[0052] in, The sign function is determined by the direction of the steering input unit 10, which determines the sign of its calculation, thereby obtaining the rotation radius information 52 of different drive wheels in the vehicle.

[0053] Next, referring to Figures 3, 4A, 4B and 7, as shown, in step S28, the yaw tracking unit 60 receives and generates a reference wheel speed command 62 based on the steering command 12, the rotation radius information 52 and the reference vehicle speed command 32, and transmits it to the wheel speed control unit 70.

[0054] The tire sideslip angle generated by the front and rear wheels during vehicle operation is affected by the lateral velocity. Considering that the dynamic response of the vehicle varies with speed, this invention calculates the lateral velocity of the current vehicle based on a kinematic model at low speeds, which is expressed by the following formula (XI): Formula (XI)

[0055] in The lateral velocity is calculated using a kinematic model. When the vehicle is at medium to high speeds, the lateral velocity can be calculated using a dynamic model, and its state-space equation is expressed by the following equation (xii): Formula (12)

[0056] in, and The equivalent steering stiffness of the front and rear axles. For rotational inertia, Lateral velocity calculated for the dynamic model.

[0057] Continuing from the above, since this invention calculates lateral velocity using two models, in this embodiment, it is set that when the velocity is lower than... At that time, the lateral velocity is calculated using a kinematic model, and the velocity is higher than When the vehicle speed is between two values, a dynamic model is used. When the vehicle speed is between two values, the weighted lateral velocity is calculated according to the ratio φ, and the equation is as follows (xiii): Formula (13)

[0058] Next, the relationship between the reference wheel speed command 62 direction and the forward rolling direction of the model's front tires is defined. If the vehicle is front-wheel drive, the equation is as follows (XIVA). If the vehicle is rear-wheel drive, the equation is as follows (XIVB). When the vehicle is cornering, it will travel according to the yaw angle velocity reference command 𝑟𝑑 required for driving, which can be expressed as follows (XV). During the process, it will rotate around the center of rotation. If the vehicle is front-wheel drive, its geometric relationship is as follows (XVIA). If the vehicle is rear-wheel drive, its geometric relationship is as follows (XVIB). Formula (14A) Formula (14B) Formula (15) Equation (16A) Formula (16B)

[0059] in, The reference vehicle speed command is projected onto the speed of the model's front tires in the forward rolling direction. The line segment length is the velocity of the rear wheel tires in the forward rolling direction, projected onto the vehicle speed command. Let be the turning radius of the front wheel of the model, and be the length of the line segment. This is the turning radius of the rear wheel of the model. In fact, the turning radii of the left and right wheels can be obtained from equations (ix) and (x) above. The reference wheel speed command 62 for the left and right drive wheels can be expressed as equations (xviiA) and (xviiiA) below. If the vehicle is front-wheel drive, then combine it with equation (xviiA) above. If the vehicle is rear-wheel drive, then combine it with equation (xviiB) above. The reference wheel speed command 62 for the left and right drive wheels can be expressed as equations (xviiB) and (xviiiB) below. Equation (17A) Formula (18A) Equation (17B) Formula (18B)

[0060] Continuing from the above, another embodiment is provided. The yaw tracking unit 60 of the present invention can further perform closed-loop feedback control to correct the yaw angular velocity command 22 for compensation. The compensation mainly consists of a feedforward compensation term and a PI controller. The compensation method is as follows: Equation (19), Equation (20), and Equation (21). Formula (19) Formula (20) Formula (21)

[0061] Where 𝑘 represents the 𝑘th sampling time, For wheel speed compensation command, This represents the error value between the yaw rate command and the yaw rate. and The gain value of the PI controller for yaw rate follow-up control.

[0062] Referring again to Figure 8 and Equations (XIVA) and (XIVB), the geometric relationships in Figure 8 can be derived from the velocity reference command. Front wheel steering angle Front wheel sideslip angle Rear wheel sideslip angle The turning radius of the front wheels can be calculated. Rear wheel turning radius The ratio is shown in equation (22). Formula (22)

[0063] Then, through the front wheel speed compensation amount The ratio of the turning radius to the calculated rear wheel speed compensation amount. As shown in equation (23) below. Formula (23)

[0064] Through rear wheel speed compensation Front wheel steering angle Rear wheel feedforward control quantity and The reference wheel speed command 62 for the rear left and rear right wheels can be calculated separately, as shown in equations (24) and (25) below. Formula (24) Formula (25)

[0065] Continuing from the above, the calculations described above describe how the reference wheel speed command 62 would be calculated if the vehicle is a four-wheel drive vehicle. Here, another embodiment is provided: if it is a front-wheel drive vehicle, the reference wheel speed command 62 of the rear wheels only needs to be removed to serve as the calculation model for the front-wheel drive vehicle.

[0066] Continuing from the above, another embodiment is provided here. If it is a rear-wheel drive vehicle, only the reference wheel speed command 62 of the front wheels needs to be removed to serve as the calculation model of the rear-wheel drive vehicle.

[0067] Next, referring back to Figure 7, in step S30, the wheel speed control unit 70 controls the drive wheel assembly 80 according to the reference wheel speed command 62. In this embodiment, the wheel speed control unit 70 mainly controls the front wheel drive torque through the RST controller, providing different driving forces to the two wheel motors when cornering, in order to maintain the stable driving of the vehicle.

[0068] The embodiments described above provide an electronic differential control method and system. After commands are provided through the steering input unit and the accelerator pedal input unit, the commands are calculated by the conversion unit, the gain unit, and the calculation unit to generate a reference vehicle speed command and a yaw rate command. The rotation radius information is then calculated based on these commands. The yaw tracking unit calculates a reference wheel speed command based on the steering command, the rotation radius information, and the reference vehicle speed command. The wheel speed control unit controls the drive wheel assembly based on the reference wheel speed command, thereby achieving stable and full-speed-range electronic differential control.

[0069] Next, another embodiment is provided. Referring again to Figures 2 to 8, the vehicle used in this embodiment is a four-wheel drive vehicle. In this embodiment, since all four wheels can be the drive wheel set 80, in addition to the calculation method used in the above embodiment, it is necessary to compensate for the front and rear wheels. Please refer to Figure 8. The compensation command for the front and rear wheels is referred to the above formula (22). The front wheel compensation command can be expressed as above formula (19), and the rear wheel compensation command can be expressed as above formula (23).

[0070] Furthermore, when the vehicle is four-wheel drive, the rotation radius information 52 further includes rotation radius information of the left front drive wheel, rotation radius information of the left rear drive wheel, rotation radius information of the right front drive wheel, and rotation radius information of the right rear drive wheel, replacing the rotation radius information 52 calculated in the above method. This allows the four drive wheels of the drive wheel assembly 80 to move forward at different wheel speeds, thus making the steering of the four-wheel drive smoother.

[0071] Since it is impossible to confirm whether the drive wheel assembly 80 moves according to the specified wheel speed and torque, the present invention provides another embodiment, which further provides a sensing device on the drive wheel assembly 80 to sense the movement of the drive wheel assembly 80 and provide feedback.

[0072] Another embodiment of the present invention is shown in Figure 9, which is a flowchart of the electronic differential control method of the present invention. As shown in the figure, except for steps S27 and S29, the rest are described in the foregoing embodiments and will not be repeated here. In this embodiment, steps S27 and S29 are described together, but this is not a limitation. The embodiments of the present invention can also be executed by adding step S27 or step S29 separately. The steps of an electronic differential control method of the present invention will be described in detail below:

[0073] Step S27: The second sensing device senses the yaw rate feedback information of the vehicle and transmits the yaw rate feedback information back to the yaw tracking unit;

[0074] Step S29: The first sensing device senses the feedback information of the drive wheel assembly and transmits the feedback information back to the wheel speed control unit.

[0075] Next, please refer to Figure 10, which is a schematic diagram of the electronic differential control system of the present invention. As shown in the figure, an electronic differential control system 3 of the present invention will be described in detail, which includes: a steering input unit 10; a calculation module 5, which includes: a gainer 20 electrically connected to the steering input unit 10; a conversion unit 30 electrically connected to the gainer 20; an accelerator pedal input unit 40 electrically connected to the conversion unit 30; a calculation unit 50 electrically connected to the gainer 20, the conversion unit 30, and the steering input unit 10; and a yaw tracking unit 60 electrically connected to the steering input unit 10. Unit 10, the calculation unit 50, and the conversion unit 30; a wheel speed control unit 70 electrically connected to the yaw tracking unit 60; a vehicle 110 comprising: a drive wheel assembly 80 electrically connected to the wheel speed control unit 70, the drive wheel assembly 80 further comprising: a first sensing device 84 disposed on the drive wheel assembly 80 for sensing feedback information 86 of the drive wheel assembly 80; and a second sensing device 112 disposed on the vehicle 110 for sensing yaw angular velocity feedback information 114 of the vehicle 110.

[0076] The steps will be described in detail below. Referring again to Figure 10, in step S27, the second sensing device 112 senses the yaw rate feedback information 114 of one of the vehicles 110 and transmits the yaw rate feedback information 114 back to the yaw tracking unit 60 so that in step S28 the yaw tracking unit 60 can use the yaw rate feedback information 114 to perform calculations.

[0077] Continuing from the above, in this embodiment, the yaw rate feedback information 114 can be one of the yaw rates of the vehicle 110. The purpose of the yaw rate feedback information 114 is to report the current yaw rate of the vehicle 110 so that the yaw tracking unit 60 can compensate and adjust the yaw rate command 22.

[0078] Referring again to Figure 10, in step S29, the first sensing device 84 senses the feedback information 86 of the drive wheel assembly 80 and transmits the feedback information 86 back to the wheel speed control unit 70.

[0079] Continuing from the above, in this embodiment, the feedback information 86 can be a wheel speed, a rotational speed, or a torque of the drive wheel assembly 80. The purpose of the feedback information 86 is to report whether the drive wheel assembly 80 is moving according to the correct wheel speed and torque, so that the wheel speed control unit 70 can adjust the reference wheel speed command 62.

[0080] The embodiments described above provide an electronic differential control method and system. After commands are provided through a steering input unit and an accelerator pedal input unit, a conversion unit, a gain unit, and a calculation unit calculate the commands to generate a reference vehicle speed command and a yaw rate command. The rotation radius information is then calculated based on this. The yaw tracking unit calculates a reference wheel speed command based on the steering input command, rotation radius information, reference vehicle speed command, and yaw rate feedback information. The wheel speed control unit controls the drive wheel assembly based on the reference wheel speed command and feedback information. The feedback information from the drive wheel assembly is transmitted back to the wheel speed control unit via a sensing device, thereby achieving stable and full-speed-range electronic differential control.

[0081] Therefore, this invention is indeed novel, inventive, and industrially applicable, and undoubtedly meets the requirements for patent application under the Patent Law of our country. Thus, we hereby file an invention patent application in accordance with the law, and earnestly pray that the Bureau will grant the patent as soon as possible.

[0082] However, the above description is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention. All equivalent changes and modifications made to the shape, structure, features and spirit described in the claims of the present invention should be included in the scope of the claims of the present invention.

[0083] S10-S30: Steps 1: Electronic differential control system 2: Electronic differential control system 3: Electronic differential control system 5: Computing Module 10: Steering Input Unit 12: Turning command 20: Gainer 22: Yaw rate command 30: Conversion Unit 32: Reference vehicle speed command 40: Accelerator pedal input unit 42: Torque Requirement Command 50: Computing Unit 52: Rotation radius information 60: Yaw tracking unit 62: Reference wheel speed command 70: Wheel speed control unit 72: Interference Torque 80: Drive wheel set 84: First sensing device 86: Feedback Information 110: Vehicle 112: Second sensing device 114: Yaw rate feedback information

Claims

1. An electronic differential control method, applied to a vehicle controlling a drive wheel assembly via a steering input unit, an accelerator pedal input unit, and a wheel speed control unit during cornering, comprising: a calculation module receiving a steering command from the steering input unit and a torque demand command from the accelerator pedal input unit; the calculation module generating a reference vehicle speed command based on the torque demand command, generating a yaw rate command based on the reference vehicle speed command and the steering command, calculating and generating rotation radius information based on the steering command, the reference vehicle speed command, and the yaw rate command, generating a reference wheel speed command based on the steering command, the rotation radius information, and the reference vehicle speed command, and transmitting it to the wheel speed control unit; and the wheel speed control unit controlling the drive wheel assembly based on the reference wheel speed command.

2. The electronic differential control method as described in claim 1, wherein the steps of the calculation module generating a reference vehicle speed command based on the torque demand command, generating a yaw rate command based on the reference vehicle speed command and the steering command, calculating and generating a rotation radius information based on the steering command, the reference vehicle speed command, and the yaw rate command, and generating a reference wheel speed command based on the steering command, the rotation radius information, and the reference vehicle speed command and transmitting it to the wheel speed control unit, further include the steps of: a conversion unit generating a reference vehicle speed command based on the torque demand command; a gainer receiving and generating a yaw rate command based on the reference vehicle speed command and the steering command; a calculation unit receiving and calculating and generating a rotation radius information based on the steering command, the reference vehicle speed command, and the yaw rate command; and a yaw tracking unit receiving and generating a reference wheel speed command based on the steering command, the rotation radius information, and the reference vehicle speed command and transmitting it to the wheel speed control unit.

3. The electronic differential control method as described in claim 1, wherein in the steps of the calculation module generating a reference vehicle speed command based on the torque demand command, generating a yaw rate command based on the reference vehicle speed command and the steering command, calculating and generating rotation radius information based on the steering command, the reference vehicle speed command and the yaw rate command, and generating a reference wheel speed command based on the steering command, the rotation radius information and the reference vehicle speed command and transmitting it to the wheel speed control unit, the rotation radius information further includes rotation radius information of a left front drive wheel, rotation radius information of a left rear drive wheel, rotation radius information of a right front drive wheel and rotation radius information of a right rear drive wheel.

4. The electronic differential control method as described in claim 2, wherein after the step of a yaw tracking unit receiving and generating a reference wheel speed command based on the steering command, the rotation radius information and the reference vehicle speed command and transmitting it to the wheel speed control unit, the method further includes the step of: a first sensing device sensing feedback information of the drive wheel assembly and transmitting the feedback information back to the wheel speed control unit.

5. The electronic differential control method as described in claim 2, wherein after a calculation unit receives and calculates and generates a rotation radius information based on the steering command, the reference vehicle speed command and the yaw rate command, the method further includes the step of: a second sensing device sensing yaw rate feedback information of a vehicle and transmitting the yaw rate feedback information back to the yaw tracking unit.

6. An electronic differential control system, applied to a vehicle controlling a drive wheel assembly during cornering via a steering input unit, an accelerator pedal input unit, and a wheel speed control unit, comprising: the steering input unit; a computing module connected to the steering input unit; the accelerator pedal input unit connected to the computing module; the wheel speed control unit electrically connected to the computing module; and the drive wheel assembly electrically connected to the wheel speed control unit; wherein... The calculation module receives a steering command from the steering input unit and a torque demand command from the accelerator pedal input unit; the calculation module generates a reference vehicle speed command based on the torque demand command, and generates a yaw rate command based on the reference vehicle speed command and the steering command; it calculates and generates rotation radius information based on the steering command, the reference vehicle speed command, and the yaw rate command; it then generates a reference wheel speed command based on the steering command, the rotation radius information, and the reference vehicle speed command and transmits it to the wheel speed control unit; and the wheel speed control unit controls the drive wheel assembly based on the reference wheel speed command.

7. The electronic differential control system as described in claim 6, wherein the computing module further comprises: a gainer electrically connected to the steering input unit; a conversion unit electrically connected to the gainer; an accelerator pedal input unit electrically connected to the conversion unit; a computing unit electrically connected to the gainer, the conversion unit, and the steering input unit; and a yaw tracking unit electrically connected to the steering input unit, the computing unit, the conversion unit, and the wheel speed control unit; wherein, The conversion unit generates a reference vehicle speed command based on the torque demand command; the gainer receives and generates a yaw rate command based on the reference vehicle speed command and the steering command; the calculation unit receives and calculates and generates a rotation radius information based on the steering command, the reference vehicle speed command, and the yaw rate command; and the yaw tracking unit receives and generates a reference wheel speed command based on the steering command, the rotation radius information, and the reference vehicle speed command and transmits it to the wheel speed control unit.

8. The electronic differential control system as described in claim 6, wherein the rotation radius information further includes rotation radius information of a left front drive wheel, rotation radius information of a left rear drive wheel, rotation radius information of a right front drive wheel, and rotation radius information of a right rear drive wheel.

9. The electronic differential control system as described in claim 6, wherein the drive wheel assembly is further disposed on the vehicle, the vehicle further comprising: a first sensing device disposed on the drive wheel assembly for sensing feedback information from the drive wheel assembly; and a second sensing device disposed on the vehicle for sensing yaw rate feedback information from the vehicle; wherein... The first sensing device senses the feedback information of the drive wheel assembly and transmits the feedback information back to the wheel speed control unit. The second sensing device senses the yaw rate feedback information of the vehicle and transmits the yaw rate feedback information back to the yaw tracking unit.

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