Vehicle motion control system, pitching control unit and control method

Abstract

The invention provides a vehicle motion control system, a pitching control unit and a control method. The pitch control unit includes: a detection module configured to detect whether a requested braking level is greater than a braking threshold level; a first calculation module configured to calculate an actual pitching state and a target pitching state of the vehicle when the detection result is positive; the second calculation module is configured to calculate a first pitching moment by adopting a feedforward control algorithm and calculate a second pitching moment by adopting a feedback control algorithm; and the third calculation module is configured to calculate a plurality of adjusting forces according to the first pitching moment and the second pitching moment, and the adjusting forces are respectively used for adjusting forces generated by actuators, coupled with the wheels, of the full-active suspension system, so that the actual pitching state of the vehicle is close to the target pitching state as much as possible or consistent with the target pitching state as much as possible.

Description

Technical Field

[0001] The present invention generally belongs to the technical field of vehicle motion control, and in particular, the present invention relates to a vehicle motion control system, a pitch control unit and a pitch control method. Background Art

[0002] In order to improve the ride smoothness of vehicles (especially large vehicles such as SUVs and MPVs or electric vehicles with heavy batteries), a softer suspension system is usually used. However, this practice often causes the vehicle to produce uncomfortable pitching motion during braking.

[0003] To address this problem, one solution in the prior art is to use Continuous Damping Control (CDC) to improve it. However, the damper may not be able to generate enough damping force to completely eliminate the pitching motion. Another solution in the prior art is to adjust the distribution of braking torque between the front and rear axles of the vehicle to reduce the pitching. However, the implementation effect of this method is limited by the geometric design of the vehicle suspension, because some suspension designs may not be suitable for adjusting the distribution of braking torque. Summary of the invention

[0004] In this context, the present invention aims to provide a pitch control solution based on a fully active suspension (Fully Active Suspension), which is suitable for both driver driving mode and autonomous driving mode.

[0005] According to one embodiment of the present invention, there is provided a pitch control unit for a vehicle, comprising: a detection module, configured to detect whether a requested braking level is greater than a braking threshold level; a first calculation module, configured to calculate an actual pitch state and a target pitch state of the vehicle when the detection result is positive, the actual pitch state comprising first and second actual pitch parameters, and the target pitch state comprising first and second target pitch parameters; a second calculation module, configured to calculate a first pitch moment according to the first actual pitch parameter and the first target pitch parameter and using a feedforward control algorithm, and calculate a second pitch moment according to the second actual pitch parameter and the second target pitch parameter and using a feedback control algorithm; and a third calculation module, configured to calculate a plurality of adjustment forces according to the first pitch moment and the second pitch moment, respectively used to adjust the forces generated by actuators coupled to each wheel of the fully active suspension system, so that the actual pitch state of the vehicle is as close as possible to the target pitch state or consistent with the target pitch state.

[0006] According to another embodiment of the present invention, a pitch control method for a vehicle is provided, comprising: detecting whether a requested braking level is greater than a braking threshold level; when the detection result is positive, calculating an actual pitch state and a target pitch state of the vehicle, the actual pitch state comprising first and second actual pitch parameters, and the target pitch state comprising first and second target pitch parameters; calculating a first pitch moment based on the first actual pitch parameter and the first target pitch parameter and using a feedforward control algorithm, and calculating a second pitch moment based on the second actual pitch parameter and the second target pitch parameter and using a feedback control algorithm; and calculating a plurality of adjustment forces based on the first pitch moment and the second pitch moment, respectively used to adjust the forces generated by actuators coupled to each wheel of the fully active suspension system, so that the actual pitch state of the vehicle is as close as possible to the target pitch state or consistent with the target pitch state.

[0007] According to another embodiment of the present invention, a vehicle motion control system is provided, which includes: a pitch control unit as described above; a suspension control unit; and a plurality of actuators, which are respectively coupled to each wheel and generate forces that affect the pitch motion of the vehicle; wherein the suspension control unit receives a plurality of adjustment forces from the pitch control unit, and adjusts the forces generated by the plurality of actuators according to the plurality of adjustment forces.

[0008] According to yet another embodiment of the present invention, a computer program product is provided, which includes computer executable instructions, and when the instructions are executed, one or more processors are caused to perform the pitch control method as described above.

[0009] A summary of the main aspects of the present invention is provided above so that these aspects can be basically understood. This summary is not intended to describe the key or important elements of all aspects of the present invention, nor is it intended to limit the scope of any or all aspects of the present invention. The purpose of this summary is to provide some implementations of these aspects in a simplified form as a preface to the detailed description that will be provided later. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The technical solution of the present invention will become clearer from the following detailed description in conjunction with the accompanying drawings. It is understood that these drawings are only used for exemplary description and are not intended to limit the scope of protection of the present invention.

[0011] Figure 1 is a schematic block diagram of a vehicle motion control system according to an embodiment of the present invention.

[0012] Figure 2 is a schematic block diagram of a pitch control unit according to an embodiment of the present invention.

[0013] Figure 3A and Figure 3BA fully active suspension system according to an embodiment of the present invention is schematically shown.

[0014] Figure 4 is a flow chart of a vehicle pitch control method according to an embodiment of the present invention.

[0015] Figure 5 Multiple parameters of the pitch motion model according to an embodiment of the present invention are schematically shown. DETAILED DESCRIPTION

[0016] The specific implementation of the present invention is described below in conjunction with the accompanying drawings.

[0017] Figure 1 FIG. 1 shows a vehicle motion control system 100 according to an embodiment of the present invention, which is arranged on a vehicle. Figure 1 As shown, the vehicle motion control system 100 includes a sensor unit 10, a pitch control unit 20, a human machine interface (HMI) 30, a suspension control unit 40, and a plurality of actuators 51-54.

[0018] The sensor unit 10 provides sensor information (Info_1) related to the vehicle motion state, such as the wheel speed of each wheel, the vehicle speed, the brake pedal travel, the accelerator pedal opening, the driver force on the accelerator pedal, the height of the vehicle center of gravity, etc. It is understood that the information related to the vehicle motion state can be obtained directly from the measurement results of the sensor, or by calculating the measurement results of the sensor. For example, the wheel speed of each wheel can be measured by a wheel speed sensor, and the vehicle speed can be directly measured or calculated by calculating the wheel speed of each wheel.

[0019] In one embodiment, the sensor unit 10 may include sensors for sensing parameters such as wheel speed, vehicle speed, and accelerator pedal position, and may also include a receiving unit for receiving information related to the vehicle operating status from an edge server, a cloud server, or other vehicles in the Internet of Vehicles via V2X (Vehicle to Everything) communication.

[0020] When the pitch control unit 20 predicts that "over-pitch" (i.e., unstable pitch motion) will occur during the vehicle braking process, it calculates the regulating force (F) for eliminating or reducing the pitch motion of the vehicle based on the sensor information (Info_1) from the sensor unit 10 and the target deceleration information (Info_2) from the driving assistance function module of the vehicle. FL ,F FR ,F RL ,F RR ). These regulating forces are used, for example, to regulate vertical forces relative to the vehicle body.

[0021] In one embodiment, the pitch control unit 20 is implemented to include: a detection module 21 for detecting whether "over-pitch" is about to occur, a first calculation module 22 for calculating the actual pitch state and the target pitch state of the vehicle, a second calculation module 23 for calculating the pitch moment, a third calculation module 24 for calculating multiple adjustment forces, and an adjustment module 25 for adjusting the target pitch state. These modules are divided according to function, and the specific implementation method or physical location of these modules is not limited. For example, these modules can be implemented on the same chip or circuit, or on different chips or circuits. For example, each module can be further divided into multiple sub-modules, or two or more of these modules can be merged into one module.

[0022] In one embodiment, the pitch control unit 20 and its various modules can be implemented in hardware or software or a combination of software and hardware. For the part implemented in hardware, it can be implemented in one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, electronic units designed to perform their functions, or a combination thereof. For the part implemented in software, it can be implemented with the help of microcodes, program codes or code segments, and they can also be stored in a machine-readable storage medium such as a storage component.

[0023] In one embodiment, the pitch control unit 20 may be arranged in an electronic control unit (ECU) of the vehicle, or in a vehicle body control unit (VCU) of the vehicle, or in a domain controller of the vehicle. In addition, the pitch control unit 20 may also be implemented as follows: some of its multiple functional modules are arranged in the vehicle ECU, and another part of its functional modules are arranged in the vehicle VCU.

[0024] Below, see Figure 3A and Figure 3B The suspension control unit 40 and the plurality of actuators 51 to 54 are introduced. The above-mentioned regulating force will be clearly described in this introduction.

[0025] Figure 3A A fully active suspension system according to an embodiment of the present invention is shown, the system comprising a suspension control unit 40 and a plurality of active actuators 51 - 54. For the sake of brevity and clarity, descriptions of other components of the fully active suspension system are omitted herein.

[0026] The multiple actuators (active actuators) 51-54 in the fully active suspension system are coupled to the four wheels of the vehicle, that is, the actuator 51 is coupled to the left front wheel FL, the actuator 52 is coupled to the right front wheel, the actuator 53 is coupled to the left rear wheel, and the actuator 54 is coupled to the right rear wheel. Each actuator can be installed between the vehicle body and a corresponding wheel, and affects the pitch state (pitch motion) of the vehicle by generating a force (in some places below, this force is referred to as the actuator force, that is, the force generated by the actuator). These actuators can generate force by motor drive, or by a motor combined with hydraulic elements (such as hydraulic lines and hydraulic valves). The suspension control unit 40 controls each actuator. For example, the suspension control unit 40 receives a plurality of adjustment forces from the pitch control unit 20, and adjusts the actuator forces generated by each actuator according to these adjustment forces.

[0027] For clarity, Figure 3B In the description, actuator 51 is taken as an example. Figure 3B As shown, the suspension control unit 40 adjusts the pressure according to the received adjustment force F FL The actuator 51 coupled to the left front wheel FL is controlled so that the actuator force generated by the actuator is adjusted accordingly according to the adjustment force.

[0028] It should be noted that the active actuator in the embodiment of the present invention can be driven by an electric motor or other types of drive units to generate the desired force. The present invention does not limit the specific implementation of the active actuator. "Active" is relative to "passive". For example, in a suspension system, springs and shock absorbers are both passive actuators. The force generated by the spring is related to its deformation, while the force generated by the shock absorber is related to the movement speed of its push rod, so these passive actuators have certain limitations in application. In contrast, the active actuator according to the embodiment of the present invention can generate a force large enough to adjust the pitch of the vehicle, without being limited by the vehicle speed or the suspension geometry.

[0029] Return to see Figure 1 The human-machine interface (HMI) 30 is used to interact with the vehicle user and receive the pitch state of the vehicle desired by the user, that is, the pitch state requested by the user (REQ). The HMI 30 sends the pitch state desired by the user to the pitch control unit 20, so that the pitch control unit 20 adjusts the target pitch state according to the user's expectation, thereby satisfying the user's expectation.

[0030] In one implementation, the HMI 30 uses a touch screen, such as a central control display screen or a head-up display of a vehicle. In this implementation, the vehicle user inputs the desired pitch state by operating the relevant modules on the touch screen (such as dragging a slider or rotating a schematic vehicle model), such as wanting a smaller pitch angle or a faster adjustment speed.

[0031] In another implementation, the HMI 30 uses a voice control interface. In this implementation, the vehicle user can express the desired pitch state through voice, such as "pitch a little smaller" or "adjust faster", etc. The HMI 30 will recognize the received voice, extract the instruction from it, and send the instruction to the pitch control unit 20, so that it adjusts the target pitch state accordingly according to the voice instruction to achieve the pitch state desired by the user.

[0032] In the embodiment of the present invention, the vehicle user can include multiple roles, and is not limited to the vehicle driver. For example, in addition to the vehicle driver, the vehicle user can also include the vehicle occupants, the developer of the vehicle system, the purchaser of the vehicle system, and the like.

[0033] Figure 4 is a flow chart of a vehicle pitch control method 400 according to an embodiment of the present invention. The method 400 can be executed by the pitch control unit 40 described above.

[0034] See also Figure 4 In box 402, the detection module 21 detects during the vehicle braking process whether the requested braking level is greater than the braking threshold level, thereby detecting whether the vehicle will experience "over-pitch" (ie, unstable pitching motion).

[0035] The braking threshold level can be determined in advance based on the suspension stiffness of the vehicle and the preset speed (for example, the speed limit of the vehicle on the urban road), and by using real vehicle testing and / or model calculation. The braking threshold level can be regarded as a critical level, that is, if the braking level of the vehicle exceeds the braking threshold level, "over-pitch" will occur, which will affect the stability and comfort of the vehicle; on the contrary, the vehicle braking will not cause "over-pitch", and the vehicle can brake stably. In addition, the detection module 21 can adjust the braking threshold level according to the current vehicle speed, because at a higher speed, the vehicle is more susceptible to the influence of the braking force and produces over-pitch; on the contrary, at a lower speed, the vehicle reacts more gently to the braking force, and a larger braking force can be allowed without causing over-pitch. For example, if the current vehicle speed is greater than the preset vehicle speed, the braking threshold level is reduced; if the current vehicle speed is less than the preset vehicle speed, the braking threshold level is increased; if the current vehicle speed is exactly equal to the preset vehicle speed, the braking threshold level is kept unchanged.

[0036] Next, some embodiments of block 402 (blocks 4021 and 4022) are introduced.

[0037] In one embodiment, referring to block 4021, the vehicle is operated in the driver driving mode. The detection module 21 detects whether the braking level requested by the driver is greater than the braking threshold level. In this embodiment, different parameters can be detected for different types of brake pedals. The following introduces the situations of different types of brake pedals.

[0038] In the case where the brake pedal is a travel-type brake pedal, the braking intention parameter characterizing the driver's braking intention includes the travel of the brake pedal and the rate of change of the travel. In this case, the detection module 21 detects whether the following conditions are met: 1) the travel of the brake pedal is greater than or equal to the established pedal travel threshold; 2) the rate of change of the travel is greater than or equal to the travel change rate threshold. If both of the above conditions are met, it means that the braking level requested by the driver is detected to be greater than the braking threshold level, and the detection result of box 402 is positive. If at least one of the above conditions is not met, it means that the braking level requested by the driver is not detected to be greater than the braking threshold level, and the detection result of box 402 is negative.

[0039] In the case where the brake pedal is a pressure-type brake pedal, the braking intention parameter characterizing the driver's braking intention includes the driver force received on the brake pedal and the rate of change of the driver force. In this case, the detection module 21 detects whether the following conditions are met: 1) the driver force received on the brake pedal is greater than or equal to the driver force threshold; 2) the rate of change of the driver force is greater than or equal to the driver force change rate threshold. If both of the above conditions are met, it means that the braking level requested by the driver is detected to be greater than the braking threshold level, and the detection result of box 402 is positive. If at least one of the above conditions is not met, it means that the braking level requested by the driver is not detected to be greater than the braking threshold level, and the detection result of box 402 is negative.

[0040] In the case of single pedal mode, the braking intention parameters characterizing the driver's braking intention include the accelerator pedal opening and the rate of change of the accelerator pedal opening. In this case, the detection module 21 detects whether the following conditions are met: 1) the accelerator pedal opening is greater than or equal to the accelerator pedal opening threshold; 2) the rate of change of the accelerator pedal opening is greater than or equal to the accelerator pedal opening rate of change threshold. If both of the above conditions are met, it means that the braking level requested by the driver is detected to be greater than the braking threshold level, and the detection result of box 402 is positive. If at least one of the above conditions is not met, it means that the braking level requested by the driver is not detected to be greater than the braking threshold level, and the detection result of box 402 is negative.

[0041] It should be understood that the single-pedal mode is mainly used in pure electric vehicles and hybrid vehicles. This mode allows the driver to accelerate, decelerate, brake, etc. by lightly stepping on or releasing the accelerator pedal without using the brake pedal. In the single-pedal mode, when the driver steps on the accelerator pedal, the vehicle will accelerate; when the driver gradually releases the accelerator pedal, the electric motor will automatically decelerate and transform into a generator, converting kinetic energy into electrical energy and storing it in the battery, while achieving vehicle deceleration and braking. The braking force varies with the degree to which the accelerator pedal is lifted.

[0042] In another embodiment, referring to block 4022, the vehicle is operated in the automatic driving mode. The detection module 21 detects whether the braking level requested by the automatic driving system is greater than the braking threshold level. Some implementation methods of this embodiment are described below.

[0043] In one embodiment, the braking request of the autonomous driving system includes a target deceleration and a rate of change of the target deceleration. In this embodiment, the detection module 21 detects whether the following conditions are met: 1) the target deceleration is greater than or equal to the target deceleration threshold; 2) the rate of change of the target deceleration is greater than or equal to the target deceleration change rate threshold. If both of the above conditions are met, it means that the braking level requested by the autonomous driving system is detected to be greater than the braking threshold level, and the detection result of box 402 is positive. If at least one of the above conditions is not met, it means that the braking level requested by the autonomous driving system is not detected to be greater than the braking threshold level, and the detection result of box 402 is negative.

[0044] In another embodiment, the braking request of the automatic driving system includes a target braking force and a rate of change of the target braking force. In this embodiment, the detection module 21 detects whether the following conditions are met: 1) the target braking force is greater than or equal to the target braking force threshold; 2) the rate of change of the target braking force is greater than or equal to the target braking force change rate threshold. If both of the above conditions are met, it means that the braking level requested by the automatic driving system is detected to be greater than the braking threshold level, and the detection result of box 402 is positive. If at least one of the above conditions is not met, it means that the braking level requested by the automatic driving system is not detected to be greater than the braking threshold level, and the detection result of box 402 is negative.

[0045] In yet another embodiment, the braking request of the automatic driving system includes a target braking torque and a rate of change of the target braking torque. In this embodiment, the detection module 21 detects whether the following conditions are met: 1) the target braking torque is greater than or equal to the target braking torque threshold; 2) the rate of change of the target braking torque is greater than or equal to the target braking torque rate of change threshold. If both of the above conditions are met, it means that the braking level requested by the automatic driving system is detected to be greater than the braking threshold level, and the detection result of box 402 is positive. If at least one of the above conditions is not met, it means that the braking level requested by the automatic driving system is not detected to be greater than the braking threshold level, and the detection result of box 402 is negative.

[0046] In addition, there may be a situation where the braking request of the autonomous driving system includes a combination of the above three implementation modes, for example, the braking request of the autonomous driving system includes two or more of the following items: 1) target deceleration and the rate of change of the target deceleration; 2) target braking force and the rate of change of the target braking force; and 3) target braking torque and the rate of change of the target braking torque. In this combination, it can be determined whether each of the two or more items is satisfied according to the above method. If each item is satisfied, the detection result of box 402 is positive; if at least one item is not satisfied, the detection result of box 402 is negative.

[0047] In the above description of the detection embodiments in the driver driving mode and the automatic driving mode, multiple thresholds are involved, such as the brake pedal travel threshold, the driver force threshold, the target deceleration threshold, etc. These thresholds are used to characterize the braking threshold level, are predetermined, and can be adjusted according to the current vehicle speed. The above description of the braking threshold level also applies to these thresholds.

[0048] If the detection result of box 402 is negative, it means that the current braking condition of the vehicle will not cause the "over-pitch" phenomenon, and the subsequent calculations will not be performed, but the detection of box 402 will continue to be performed until the detection result is positive.

[0049] If the result of the detection in block 402 is positive, it means that an “over pitch” phenomenon is about to occur, and the method 400 proceeds to block 404 .

[0050] In block 404, the first calculation module 22 calculates an actual pitch state and a target pitch state of the vehicle. The actual pitch state includes a first actual pitch parameter and a second actual pitch parameter, wherein the first actual pitch parameter includes an angular acceleration of an actual pitch angle, and the second actual pitch parameter includes an actual pitch angle and an angular velocity of the actual pitch angle. The target pitch state includes a first target pitch parameter and a second target pitch parameter, wherein the first target pitch parameter includes an angular acceleration of a target pitch angle, and the second target pitch parameter includes a target pitch angle and an angular velocity of the target pitch angle.

[0051] An embodiment of block 404 (blocks 4041 and 4042) is described below.

[0052] In one embodiment, referring to block 4041 , the first calculation module 22 uses the first pitch motion model to calculate the actual pitch angle of the vehicle, the angular velocity of the actual pitch angle, and the angular acceleration of the actual pitch angle.

[0053] The first pitch motion model is a mathematical model used to describe the actual pitch behavior of the vehicle. It contains multiple parameters that can affect the pitch motion of the vehicle. These parameters include but are not limited to: pitch moment of inertia (Jx), sprung mass (SM), center of gravity height (H g ), pitch center height (H p ), the distance between the actuator force point and the pitch center on the front and rear axes (Lpf, Lpr), and the equivalent pitch stiffness of the front and rear axle springs (K SF ,K SR The first pitch motion model may be expressed in the form of a graph (e.g., a graph expressing the relationship between the parameter that can affect the pitch motion of the vehicle and the pitch motion), a lookup table (e.g., a lookup table including pitch motions under different parameter values ​​of the parameter that can affect the pitch motion of the vehicle), or a formula (e.g., a formula that quantitatively describes the relationship between the parameter that can affect the pitch motion of the vehicle and the pitch motion).

[0054] exist Figure 5 In FIG. 1 , multiple parameters that can affect the pitch motion of a vehicle are shown. Figure 5 An example of the first pitch motion model is introduced.

[0055] In one embodiment, the first pitch motion model is expressed using the following formula (1).

[0056]

[0057] In formula (1):

[0058] θ represents the actual pitch angle of the vehicle;

[0059] Angular acceleration representing the actual pitch angle of the vehicle;

[0060] F FL represents the actuator force currently generated by the actuator 51 coupled to the left front wheel;

[0061] F FR represents the actuator force currently generated by the actuator 52 coupled to the left rear wheel;

[0062] F RL represents the actuator force currently generated by the actuator 53 coupled to the left rear wheel;

[0063] F RR represents the actuator force currently generated by the actuator 54 coupled to the right rear wheel;

[0064] Jx represents the pitch moment of inertia;

[0065] SM represents the sprung mass of the vehicle;

[0066] H g Indicates the height of the vehicle's center of gravity G from the ground GND;

[0067] H p Indicates the height of the vehicle pitch center CoP from the ground GND;

[0068] Lpf represents the water level between the point of action of the actuator force on the front axle of the vehicle and the pitch center CoP

[0069] Flat distance;

[0070] Lpr represents the water level between the point of action of the actuator force on the rear axle of the vehicle and the pitch center CoP

[0071] Flat distance;

[0072] K SF represents the equivalent pitch stiffness of the front axle spring;

[0073] K SR represents the equivalent pitch stiffness of the rear axle spring;

[0074] a x Indicates the target deceleration of the vehicle.

[0075] Next, some implementation methods of the target deceleration of the vehicle are introduced.

[0076] In one embodiment, in the driver driving mode, the target deceleration is obtained based on the driver's braking request. The first calculation module 22 puts the target deceleration obtained based on the driver's braking request into formula (1).

[0077] In another embodiment, in the automatic driving mode, the target deceleration is issued by the automatic driving system. The first calculation module 22 puts the target deceleration issued by the automatic driving system into formula (1).

[0078] In another embodiment, the vehicle has enabled a driving assistance function related to braking, such as a comfort braking function, an automatic parking function, etc. At this time, the driving assistance function related to braking will issue a target deceleration of the vehicle. The first calculation module 22 brings the target deceleration issued by the driving assistance function related to braking into formula (1).

[0079] Therefore, according to formula (1) and integration operation, the angular acceleration of the actual pitch angle of the vehicle, the angular velocity of the actual pitch angle, and the actual pitch angle can be obtained.

[0080] In one embodiment, referring to block 4042, the first calculation module 22 uses the second pitch motion model to calculate the target pitch angle, the angular velocity of the target pitch angle, and the angular acceleration of the target pitch angle of the vehicle.

[0081] The second pitch motion model is a mathematical model for describing the target pitch behavior of the vehicle. The second vehicle pitch motion model is obtained by using a correction coefficient to correct some of the multiple parameters of the first pitch motion model. The second pitch motion model can be expressed by the following formula (2).

[0082]

[0083] In formula (2):

[0084] θ Tar represents the target pitch angle of the vehicle;

[0085] angular acceleration representing the target pitch angle of the vehicle;

[0086] F FL represents the actuator force currently generated by the actuator 51 coupled to the left front wheel;

[0087] F FR represents the actuator force currently generated by the actuator 52 coupled to the left rear wheel;

[0088] F RL represents the actuator force currently generated by the actuator 53 coupled to the left rear wheel;

[0089] F RR represents the actuator force currently generated by the actuator 54 coupled to the right rear wheel;

[0090] J x_Tar The pitch moment of inertia J xand the first correction coefficient C1 is obtained, for example, J x_Tar =J x *C1;

[0091] SM Tar The sprung mass SM of the vehicle and the second correction coefficient C1 are obtained, for example, SM Tar =SM*C2;

[0092] H g Indicates the height of the vehicle's center of gravity G from the ground GND;

[0093] H p_Tar By H p and the third correction factor is obtained, for example, H p_Tar =H p *C3;

[0094] Lpf represents the horizontal distance between the point of action of the actuator force on the front axle of the vehicle and the pitch center CoP;

[0095] Lpr represents the horizontal distance between the point of action of the actuator force on the rear axle of the vehicle and the pitch center CoP;

[0096] K SF_Tar By K SF and the fourth correction factor is obtained, for example, K SF_Tar =K SF *C4;

[0097] K SR_Tar By K SR and the fifth correction factor is obtained, for example, K SR_Tar =K SR *C5;

[0098] a x Indicates the target deceleration of the vehicle.

[0099] In formula (2), the target deceleration of the vehicle is the target deceleration obtained based on the driver's braking request or the braking request of the automatic driving system. Even if the vehicle has enabled a driving assistance function related to braking, and the assistance function also issues a target deceleration, in formula (2), the target deceleration will ignore the target deceleration issued by the assistance function.

[0100] The values ​​of the correction coefficients are predetermined based on actual vehicle testing and / or model calculations, and the adjustment module 25 can adjust these coefficients within a predetermined range, such as 0 to 2. In other words, the values ​​of these correction coefficients are between 0 and 2.

[0101] The following is an introduction to each correction factor.

[0102] The first correction coefficient C1 is used to correct the pitch moment of inertia. This coefficient can affect the delay between the input target deceleration and the vehicle body pitch response. The delay can be reduced by setting the value of this coefficient to less than 1; the delay can also be increased by setting the value of this coefficient to greater than 1.

[0103] The second correction coefficient C2 is used to correct the sprung mass. This coefficient parameter can affect the value of the angular acceleration of the target pitch angle of the vehicle. The angular acceleration of the target pitch angle can be reduced by setting the value of this coefficient to less than 1; the angular acceleration of the target pitch angle can also be increased by setting the value of this coefficient to greater than 1.

[0104] The third correction coefficient C3 is used to correct the vehicle pitch center height. This coefficient can affect the value of the vehicle target pitch angle and the value of the angular acceleration of the target pitch angle. The target pitch angle and the angular acceleration of the target pitch angle can be adjusted simultaneously by adjusting this coefficient.

[0105] The fourth and fifth correction coefficients C4 and C5 are used to correct the equivalent pitch stiffness of the front and rear axle springs, respectively. These two coefficients can affect the value of the vehicle's target pitch angle. These two coefficients can be adjusted simultaneously or individually. For example, the vehicle's target pitch angle can be reduced by setting the sum of C4 and C5 to be greater than 1; the vehicle's target pitch angle can also be increased by setting the sum of C4 and C5 to be less than 1.

[0106] Thus, according to formula (2) and integral operation, the angular acceleration of the target pitch angle, the angular velocity of the target pitch angle, and the target pitch angle of the vehicle can be obtained.

[0107] In block 406, the second calculation module 23 calculates the first pitch moment according to the first actual pitch parameter and the first target pitch parameter using a feedforward control algorithm, and calculates the second pitch moment according to the second actual pitch parameter and the second target pitch parameter using a feedback control algorithm. Both the first pitch moment and the second pitch moment are moments for eliminating or at least partially counteracting the pitch motion of the vehicle.

[0108] In one embodiment, referring to block 4061, the second calculation module 23 calculates the first pitch moment according to the difference between the angular acceleration of the target pitch angle and the angular acceleration of the actual pitch angle and the pitch moment of inertia. For example, the second calculation module 23 calculates the first pitch moment using the following formula (3).

[0109]

[0110] In formula (3), PM FF Represents the first pitch moment. For the definitions of other parameters, please refer to the above descriptions of these parameters.

[0111] In one embodiment, referring to block 4062, the second calculation module 23 calculates the second pitch moment according to the first feedback control coefficient and the difference between the actual pitch angle and the target pitch angle, and the second feedback control coefficient and the difference between the rate of change of the actual pitch angle and the rate of change of the target pitch angle. The first and second feedback coefficients are both predetermined, and the first feedback control coefficient can adjust the difference between the actual pitch angle and the target pitch angle so that the actual pitch angle is closer to the target pitch angle, and the second feedback control coefficient can adjust the overshoot and oscillation of the actual pitch angle so that the feedback system is more stable.

[0112] The second calculation module 23 can adopt a variety of feedback algorithms. For example, the second calculation module 23 performs feedback control through the actual pitch angle and the target pitch angle, and the rate of change of the actual pitch angle and the rate of change of the target pitch angle. The algorithm of feedback control is, for example, PID (proportional-integral-differential), fuzzy control, or sliding mode control, etc. The selection of these algorithms depends on the specific control requirements and system characteristics. Below, how to use PD (proportional-differential) for control is explained by way of example.

[0113] The second calculation module 23 calculates the second pitch moment according to the first feedback control coefficient and the difference between the actual pitch angle and the target pitch angle, and the second feedback control coefficient and the difference between the rate of change of the actual pitch angle and the rate of change of the target pitch angle. The first and second feedback coefficients are both predetermined, and the first feedback control coefficient can adjust the difference between the actual pitch angle and the target pitch angle so that the actual pitch angle is closer to the target pitch angle, and the second feedback control coefficient can adjust the overshoot and oscillation of the actual pitch angle so that the feedback system is more stable.

[0114] The second calculation module 23 may use the following formula (4) to calculate the second pitching moment.

[0115]

[0116] In formula (4), PM FB represents the second pitching moment, Indicates the rate of change of the target pitch angle, Indicates the rate of change of the actual pitch angle, K p represents the first feedback control coefficient, K d Represents the second feedback control coefficient. For the definitions of other parameters, please refer to the above description of these parameters.

[0117] In block 408, the third calculation module 24 calculates a plurality of adjustment forces according to the first pitch moment and the second pitch moment, which are respectively used to adjust the actuator forces generated by the fully active actuators coupled to the respective wheels, so that the actual pitch state of the vehicle is close to or the same as the target pitch state. According to an embodiment of the present invention, the plurality of adjustment forces are used to eliminate or at least partially eliminate (offset) the pitch motion of the vehicle, and will not cause the roll motion of the vehicle. That is, the actuator forces adjusted according to the adjustment forces can balance the roll moment at the roll center of the vehicle.

[0118] In one embodiment, the third calculation module 24 calculates a plurality of adjustment forces according to the following formulas (5) to (8).

[0119]

[0120]

[0121] In formulas (5) to (8), the definitions of the various parameters refer to the above descriptions of these parameters.

[0122] In addition, according to an embodiment of the present invention, when the HMI 30 receives a user request regarding a user-desired pitch state, the adjustment module 25 adjusts the first and / or second target pitch parameters in response to the user request so that the target pitch state matches (is consistent with) the user-desired pitch state.

[0123] In one embodiment, the adjustment module 25 adjusts one or more of the first to fifth correction coefficients according to the pitch state desired by the user, so that the target pitch state matches the pitch state desired by the user. For example, the adjustment includes one or more of the following: 1) adjusting the delay time between the change of the vehicle pitch motion relative to the target deceleration input by adjusting the first correction coefficient; 2) adjusting the value of the angular acceleration of the target pitch angle by adjusting the second correction coefficient; 3) adjusting the angular acceleration and the value of the pitch angle of the target pitch angle by adjusting the third correction coefficient; and 4) adjusting the value of the target pitch angle by adjusting the fourth and fifth correction coefficients.

[0124] In addition, according to an embodiment of the present invention, the detection module 21 also detects the real-time vehicle speed, and when it is detected that the vehicle is stationary based on the vehicle speed (for example, the current vehicle speed is detected to be zero or close to zero), the current pitch control is terminated.

[0125] An embodiment of the present invention further provides a machine-readable storage medium storing executable instructions, which, when executed, enable one or more processors to perform the pitch control method as described above.

[0126] An embodiment of the present invention further provides a computer program product, which includes computer executable instructions, and when the instructions are executed, one or more processors execute the pitch control method as described above.

[0127] It should be noted that in the embodiments of the present invention, the autonomous driving mode should be broadly understood to include various levels of autonomous driving and driving assistance, that is, including assisted driving with different degrees of automation. For example, in the autonomous driving mode, the vehicle can be fully autonomous or semi-autonomous, or can be driven with the help of an advanced driver assistance system.

[0128] It should be noted that all operations in the method described above are merely exemplary, and the present disclosure is not limited to any operation in the method or the order of these operations, but should cover all other equivalent transformations under the same or similar concept.

[0129] It should be noted that the processor may use any combination of one or more of the following: an appropriate central processing unit, CPU, multiprocessor, single-chip microcomputer, digital signal processor, DSP, application-specific integrated circuit, etc., capable of executing software instructions of a computer program stored in the memory. Therefore, the memory may be considered as part of or forming part of a computer program product. The processor may be configured to execute a computer program stored therein to cause the controller to perform the required steps.

[0130] It should be noted that software should be broadly considered to represent instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software modules, applications, software applications, software packages, routines, subroutines, objects, running threads, processes, functions, etc. The software may reside in a computer-readable medium. The computer-readable medium may include, for example, a memory, which may be, for example, a magnetic storage device (e.g., a hard disk, a floppy disk, a magnetic stripe), an optical disk, a smart card, a flash memory device, a random access memory (RAM), a read-only memory (ROM), a programmable ROM (PROM), an erasable PROM (EPROM), an electrically erasable PROM (EEPROM), a register, or a removable disk. Although the memory is shown as being separate from the processor in the various aspects provided in the present disclosure, the memory may also be located inside the processor (e.g., a cache or a register).

[0131] The above description is provided to enable any person skilled in the art to implement the various aspects described herein. Various modifications to these aspects are apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. Therefore, the claims are not intended to be limited to the aspects shown herein. All structural and functional equivalents of elements of various aspects described in this disclosure that are known or to be known to those skilled in the art will be expressly included herein by reference and are intended to be covered by the claims.

Claims

1. A pitch control unit for a vehicle, comprising: a detection module configured to detect whether the requested braking level is greater than a braking threshold level; A first calculation module is configured to calculate an actual pitch state and a target pitch state of the vehicle when the detection result is positive, the actual pitch state comprising first and second actual pitch parameters, and the target pitch state comprising first and second target pitch parameters; a second calculation module, configured to: calculate a first pitch moment according to a first actual pitch parameter and a first target pitch parameter by adopting a feedforward control algorithm, and calculate a second pitch moment according to a second actual pitch parameter and a second target pitch parameter by adopting a feedback control algorithm; as well as The third calculation module is configured to calculate multiple adjustment forces based on the first pitch moment and the second pitch moment, which are respectively used to adjust the forces generated by the actuators coupled to each wheel of the fully active suspension system, so that the actual pitch state of the vehicle is as close as possible to the target pitch state or is consistent with the target pitch state.

2. The pitch control unit according to claim 1, wherein: The detection module is configured to: in the driver mode, detect whether the braking level requested by the driver is greater than a braking threshold level; and In the autonomous driving mode, the braking level requested by the autonomous driving system is detected to detect whether the requested braking level is greater than a braking threshold level.

3. The pitch control unit according to claim 1, wherein: The detection module is configured to: in the driver mode, detect whether the braking level requested by the driver is greater than the braking threshold level, and Detecting the driver's requested braking level includes: - When the vehicle is equipped with a travel-type brake pedal, detecting the brake pedal travel based on the driver's operation and the rate of change of the travel; - when the vehicle is equipped with a pressure-type brake pedal, detecting the driver force received on the brake pedal and the rate of change of the driver force; -In the one-pedal mode, the accelerator pedal opening degree and the rate of change of the accelerator pedal opening degree based on the driver's operation are detected.

4. The pitch control unit according to claim 1, wherein: The detection module is configured to: in the automatic driving mode, detect whether the braking level requested by the automatic driving system is greater than the braking threshold level, and Detecting the level of braking requested by the automated driving system includes detecting that the automated driving system: - the target deceleration and the rate of change of the target deceleration; and / or - the target braking force and the rate of change of the target braking force; and / or -Target braking torque and rate of change of target braking torque.

5. The pitch control unit according to any one of claims 1 to 4, wherein: The braking threshold level is predetermined based on the vehicle's suspension stiffness and a preset vehicle speed, and The detection module adjusts the braking threshold level according to a comparison result between the current vehicle speed and the preset vehicle speed.

6. The pitch control unit according to claim 1, wherein: The first actual pitch parameter includes an angular acceleration of an actual pitch angle, and the second actual pitch parameter includes a target pitch angle and an angular velocity of the target pitch angle; and The first target pitch parameter includes an angular acceleration of a target pitch angle, and the second target pitch parameter includes a target pitch angle and an angular velocity of the target pitch angle.

7. The pitch control unit according to any one of claims 1 to 6, wherein: The first calculation module is configured to calculate the first and second actual pitch parameters using a first pitch motion model, and the first pitch motion model includes a plurality of parameters that can affect the pitch motion of the vehicle.

8. The pitch control unit according to claim 7, wherein: The first calculation module is configured to calculate first and second target pitch parameters using a second pitch motion model, and The second pitch motion model is obtained by using a correction coefficient to correct at least part of the multiple parameters.

9. The pitch control unit according to claim 8, wherein: The plurality of parameters include at least: pitch moment of inertia, sprung mass, center of gravity height, pitch center height, distance between the point of action of the force generated by the actuators on the front and rear axles and the pitch center, and equivalent pitch stiffness of the front and rear axle springs; and The correction coefficients include: a first correction coefficient for correcting the pitch moment of inertia, a second correction coefficient for correcting the sprung mass, a third correction coefficient for correcting the pitch center height, and a fourth correction coefficient for correcting the equivalent pitch stiffness of the front and rear axle springs.

10. The pitch control unit according to any one of claims 1 to 9, wherein: The second calculation module is configured to calculate a first pitch moment based on the pitch moment of inertia and a difference between an angular acceleration of an actual pitch angle and an acceleration of a target pitch angle.

11. The pitch control unit according to any one of claims 1 to 9, wherein: The second calculation module is configured to calculate a second pitch moment based on a first value obtained by a first feedback control coefficient and a difference between an actual pitch angle and a target pitch angle, and a second value obtained by a second feedback control coefficient and a difference between a rate of change of the actual pitch angle and a rate of change of the target pitch angle.

12. The pitch control unit according to any one of claims 1 to 10, wherein: The third computing module is configured to: Calculating the plurality of adjustment forces based on the sum of the first pitch moment and the second pitch moment and the distance between the point of action of the force generated by the actuator on the front and rear axles and the pitch center of the vehicle; and The plurality of adjusting forces can balance the rolling moment on the roll center of the vehicle body.

13. The pitch control unit according to claim 9, wherein: The pitch control unit further includes an adjustment module configured to: The target pitch state is adjusted according to the desired state of the vehicle pitch motion of the vehicle user received by the human-machine interface of the vehicle, so that the target pitch state is consistent with the pitch state desired by the user.

14. The pitch control unit according to claim 13, wherein: Adjusting the target pitch state includes one or more of the following: The delay time between the change of the pitch motion of the vehicle and the target deceleration input is adjusted by adjusting the first correction coefficient; The value of the angular acceleration of the target pitch angle is adjusted by adjusting the second correction coefficient; The angular acceleration and the pitch angle of the target pitch angle are adjusted simultaneously by adjusting the third correction coefficient; as well as The value of the target pitch angle is adjusted by adjusting the fourth and fifth correction coefficients.

15. A pitch control method for a vehicle, comprising: detecting whether the requested braking level is greater than a braking threshold level; When the detection result is positive, calculating an actual pitch state and a target pitch state of the vehicle, the actual pitch state comprising first and second actual pitch parameters, and the target pitch state comprising first and second target pitch parameters; Calculating a first pitch moment according to a first actual pitch parameter and a first target pitch parameter using a feedforward control algorithm, and calculating a second pitch moment according to a second actual pitch parameter and a second target pitch parameter using a feedback control algorithm; as well as A plurality of adjustment forces are calculated according to the first pitch moment and the second pitch moment, and are respectively used to adjust the forces generated by the actuators coupled to the wheels of the fully active suspension system, so that the actual pitch state of the vehicle is as close as possible to the target pitch state or is consistent with the target pitch state.

16. A vehicle motion control system, comprising: A pitch control unit as claimed in any one of claims 1 to 14; Suspension control unit; as well as A plurality of actuators are respectively coupled to each wheel and generate a force affecting the pitch motion of the vehicle; The suspension control unit receives a plurality of regulating forces from the pitch control unit, and adjusts the forces generated by the plurality of actuators according to the plurality of regulating forces.

17. A computer program product comprising computer executable instructions, which when executed cause one or more processors to perform the pitch control method of claim 15.

Images