WO2021027286A1 - 一种控制车辆稳定性的方法及设备 - Google Patents

一种控制车辆稳定性的方法及设备 Download PDF

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WO2021027286A1
WO2021027286A1 PCT/CN2020/080531 CN2020080531W WO2021027286A1 WO 2021027286 A1 WO2021027286 A1 WO 2021027286A1 CN 2020080531 W CN2020080531 W CN 2020080531W WO 2021027286 A1 WO2021027286 A1 WO 2021027286A1
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Prior art keywords
slip rate
vehicle
rear axle
front axle
target
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PCT/CN2020/080531
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English (en)
French (fr)
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刘栋豪
张永生
张伟
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华为技术有限公司
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Priority to EP20803070.0A priority Critical patent/EP3805057A4/en
Publication of WO2021027286A1 publication Critical patent/WO2021027286A1/zh
Priority to US17/326,006 priority patent/US11731611B2/en

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    • B60T8/1755Brake regulation specially adapted to control the stability of the vehicle, e.g. taking into account yaw rate or transverse acceleration in a curve
    • B60T8/17551Brake regulation specially adapted to control the stability of the vehicle, e.g. taking into account yaw rate or transverse acceleration in a curve determining control parameters related to vehicle stability used in the regulation, e.g. by calculations involving measured or detected parameters
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    • B60L15/20Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
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Definitions

  • This application relates to the technical field of smart cars, and in particular to a method and equipment for controlling vehicle stability.
  • the electronic stability program (ESP) of the vehicle body generally controls the generation of additional yaw moment by generating braking force vectors on the left and right wheels of the vehicle to improve vehicle stability.
  • the vehicle can use ESP to brake the inner rear wheels to generate additional yaw moment in the same steering direction to ensure that the vehicle is stable and follows the driver's desired trajectory, as shown in the left picture in Figure 1. Shown.
  • the vehicle can use ESP to brake on the outer front wheels to generate additional yaw moment contrary to the steering scheme to ensure that the vehicle is stable and follows the driver's desired trajectory, as shown in the right picture in Figure 1. Shown.
  • this method of generating a yaw moment through the intervention of braking force to improve vehicle stability usually sets the intervention late and the braking intervention is stronger, which reduces the driver's experience.
  • the front and rear axle distributed drive vehicles Compared with traditional centralized drive vehicles, the front and rear axle distributed drive vehicles have a set of drive systems on the front axle and the rear axle, and the two systems are coupled through control. Because the torque distribution ratio of the front and rear axles is more free, this drive architecture provides greater control freedom for the vehicle's economy, power, maneuverability and stability.
  • the distribution ratio of the front and rear axle torques will also directly affect the slip rate of the wheels, thereby affecting the steering characteristics and stability of the vehicle. Therefore, how to provide additional yaw moment to maintain vehicle stability by controlling the wheel slip rate is full of challenges in the practical engineering application of front and rear axle distributed drive electric vehicles.
  • the present application provides a method and equipment for controlling the stability of a vehicle, which are used to control the lateral stability of a front and rear axle distributed drive vehicle.
  • the present application provides a method for controlling the stability of a vehicle.
  • the method can be applied to the front and rear axle distributed drive vehicle shown in FIG. 6 and executed by a device (electronic device for short) that controls vehicle stability.
  • the method specifically includes the following steps:
  • the electronic device can perform stability control on the vehicle according to the front axle target torque and the rear axle target torque.
  • the electronic device can obtain the actual slip rate of the front axle and the actual slip rate of the rear axle, and then quickly and accurately obtain the target slip rate of the front axle and the rear axle target in line with the current driving situation
  • the slip rate may be further based on the difference between the front axle target slip rate and the front axle actual slip rate, and the difference between the rear axle target slip rate and the rear axle actual slip rate,
  • the front axle target torque and the rear axle target torque that can ensure the stability of the vehicle are determined, so that the stability control of the vehicle can be performed.
  • This method takes into account the yaw motion of the vehicle, and provides the vehicle with additional yaw moment that maintains the lateral stability of the vehicle through the compensation of the front and rear axle slip rate, so as to control the lateral stability of the vehicle and improve the vehicle's driving process. stability.
  • the front axle target slip rate and the rear axle target slip rate are obtained according to the vehicle's required yaw moment at the current moment, the real-time calculated front axle target slip rate and the rear axle target slip rate are more consistent with The driving situation of the vehicle at the current moment, that is, no matter what driving mode the vehicle is in the stability control enable, the stability of the vehicle can be quickly and accurately ensured by this method.
  • the electronic device can also, but not limited to, determine the state of the vehicle through the following methods:
  • Method 1 The electronic device determines the state of the vehicle according to the angular velocity error between the actual yaw rate and the target yaw rate of the vehicle at the current moment;
  • the electronic device can accurately determine the state of the vehicle.
  • the electronic device can determine the state of the vehicle according to the angular velocity error between the actual yaw rate of the vehicle and the target yaw rate through the following steps:
  • the electronic device obtains the longitudinal vehicle speed, the wheel steering angle, and the actual yaw rate of the vehicle at the current moment; the electronic device determines the target lateral speed according to the longitudinal vehicle speed, the wheel steering angle, and the stored steering characteristic factors. Swivel angular velocity; the electronic device calculates the angular velocity error between the actual yaw angular velocity and the target yaw angular velocity; when the angular velocity error does not fall within the threshold interval formed by the first threshold and the second threshold, Determine that the state of the vehicle is unstable; otherwise, determine that the state of the vehicle is stable.
  • the actual yaw rate can characterize the actual trajectory of the vehicle without changing the operating conditions of the vehicle
  • the target yaw rate is used to characterize the desired trajectory of the driver of the vehicle
  • the first threshold is A positive number
  • the second threshold is a negative number.
  • the electronic device can accurately determine the state of the vehicle according to the current driving situation of the vehicle.
  • the target yaw rate conforms to the following formula:
  • ⁇ d (t) is the target yaw rate
  • v x (t) is the longitudinal vehicle speed
  • ⁇ (t) is the steering angle of the wheels
  • l f is the distance from the center of mass of the vehicle to the front axle
  • L r is the distance from the center of mass of the vehicle to the rear axle
  • K is the steering characteristic factor
  • t is the current time.
  • the electronic device can accurately calculate the target yaw rate of the vehicle.
  • the electronic device may determine the required yaw moment according to the angular velocity error.
  • the required yaw moment conforms to the following formula:
  • the required yaw moment conforms to the following formula:
  • M(t) is the required yaw moment
  • sign( ⁇ (t)) is a sign function
  • ⁇ (t) is the steering angle of the wheel
  • e ⁇ (t) is the actual yaw rate and The difference between the target yaw rate
  • K Po is the proportional module gain coefficient of the vehicle in excessive steering conditions
  • K Io is the integral module gain coefficient of the vehicle in excessive steering conditions
  • K Do The differential module gain coefficient of the vehicle in an over-steering condition
  • t 0 is the moment when the state of the vehicle is unstable
  • t is the current moment
  • K Pu is the proportional module gain of the vehicle in an under-steering condition
  • the coefficients are the gain coefficients of the integral module when the vehicle is under-steered by K Iu, and the gain coefficients of the differential module when the vehicle is under-steered by the K Du .
  • the electronic device can accurately calculate the required yaw moment that can stabilize the vehicle.
  • the angular velocity error conforms to the following formula:
  • e ⁇ (t) is the angular velocity error
  • ⁇ (t) is the actual yaw angular velocity
  • ⁇ d (t) is the target yaw angular velocity
  • the electronic device may obtain the actual front axle slip rate ⁇ f (t) and the rear axle actual slip rate ⁇ f (t) of the vehicle at the current time through the following steps:
  • the electronic device can accurately determine the actual slip rate of the front axle and the actual slip rate of the rear axle according to the current driving situation of the vehicle.
  • the electronic device in a manual driving scenario, can be based on the opening of the accelerator pedal and the brake pedal in the driver input device, and the output of the manual gear rocker and/or the automatic gear controller. Gear position, according to the power optimization or energy optimization method, the initial torque T f0 of the front axle and the initial torque T r0 of the rear axle are calculated.
  • the electronic device can accurately calculate the initial torque of the front axle and the initial torque of the rear axle according to the data output by the driver input device.
  • the electronic device may calculate the initial torque T f0 of the front axle and the initial torque T r0 of the rear axle according to the braking or driving demand output by the ADAS. Through this design, the electronic device can accurately calculate the initial torque of the front axle and the initial torque of the rear axle in an autonomous driving scenario.
  • the electronic device determines the correspondence between the yaw moment of the vehicle and the slip rate of the front axle and the slip rate of the rear axle through the following steps, including:
  • the electronic device obtains the wheel steering angle, front axle side slip angle, rear axle side slip angle, front axle vertical force, and rear axle vertical force of the vehicle at the current moment; then, according to the wheel steering Angle, the front axle side slip angle, the rear axle side slip angle, the front axle vertical force and the rear axle vertical force, and the stored target correspondence relationship to establish the yaw moment and the front axle Corresponding relationship between slip rate and rear axle slip rate.
  • the target corresponding relationship is based on the corresponding relationship between the front axle lateral force and the front axle slip rate, the front and rear side slip angle, and the front axle vertical force, the rear axle lateral force and the rear axle slip rate, and the rear axle side
  • the corresponding relationship between the yaw angle and the vertical force of the rear axle, and the corresponding relationship between the yaw moment and the steering angle of the vehicle, the lateral force of the front axle, and the lateral force of the rear axle are determined.
  • the corresponding relationship between the front axle lateral force and the front axle slip rate, the front axle side slip angle, the front axle vertical force, and the rear axle lateral force and the rear axle slip rate, the rear axle side slip angle, the rear axle The corresponding relationship of the vertical force is obtained from the linear analysis of the relationship between the lateral force and the yaw rate.
  • the corresponding relationship between the yaw moment and the steering angle of the vehicle, the lateral force of the front axle, and the lateral force of the rear axle is determined by the analysis of the two-degree-of-freedom vehicle model. Therefore, through this design, the electronic device can accurately establish the corresponding relationship between the yaw moment, the front axle slip rate and the rear axle slip rate.
  • M is the yaw moment
  • is the wheel steering angle
  • C 1f and C 0f are the linearization coefficients of the front axle equivalent tire model
  • C 1r and C 0r are the rear axle equivalent tire linearization factors
  • ⁇ fd is the front axle Slip rate
  • ⁇ rd is the rear axle slip rate
  • ⁇ f is the front axle side slip angle
  • ⁇ r is the rear axle side slip angle
  • F zf is the front axle vertical force
  • F zr is the rear axle vertical force
  • l f is the distance from the center of mass of the vehicle to the front axle
  • l r is the distance from the center of mass of the vehicle to the rear axle.
  • the electronic device can determine the front axle target slip rate and the rear axle target slip rate through the following steps:
  • the electronic device determines a plurality of slip rate combinations according to the corresponding relationship between the yaw moment, the front axle slip rate and the rear axle slip rate, and the required yaw moment, wherein each slip The combination of rates includes a front axle slip rate and a rear axle slip rate; afterwards, the electronic device selects at least one of the front axle slip rate and the rear axle slip rate less than 0 from the plurality of slip rate combinations A slip rate combination; then, select the target slip rate combination with the smallest sum of the absolute value of the front axle slip rate and the absolute value of the rear axle slip rate from the at least one slip rate combination; finally, the The electronic device determines that the front axle slip rate in the target slip rate combination is the front axle target slip rate, and determines that the rear axle slip rate in the target slip rate combination is the rear axle target slip rate. Shift rate.
  • the electronic device can obtain multiple sets of solutions according to the corresponding relationship between the yaw moment, the front axle slip rate and the rear axle slip rate, and the required yaw moment.
  • the numerical value in the group solution has positive and negative values.
  • the vehicle can be braked.
  • the slip rate of the vehicle is less than 0.
  • the electronic device may reduce the front axle slip rate and the rear axle slip rate to less than 0, and the absolute value of the front axle slip rate and the rear axle slip rate
  • the sum of the absolute values of is the smallest, as two constraints, so that the target slip rate of the front axle and the target slip rate of the rear axle finally obtained by the electronic device can ensure the driving safety of the vehicle.
  • the front axle target torque conforms to the following formula:
  • the target rear axle torque conforms to the following formula:
  • T f (t) is the front axle target torque
  • T f0 is the front axle initial torque
  • e ⁇ f (t) is the difference between the front axle target slip rate and the front axle actual slip rate
  • T r (t) is the rear axle target torque
  • T r0 is the rear axle initial torque
  • e ⁇ r (t) is the difference between the rear axle target slip rate and the rear axle actual slip rate
  • K P is the gain coefficient of the proportional module
  • K I is the gain coefficient of the integral module
  • K D is the gain coefficient of the differential module
  • t 0 is the moment when the state of the vehicle is unstable
  • t is the current moment.
  • the electronic device can accurately calculate the front axle target torque and the rear axle target torque, so that the stability control of the vehicle can be performed according to the front axle target torque and the rear axle target torque.
  • an embodiment of the present application provides a device for controlling the stability of a vehicle, including a unit for executing each step in the above first aspect.
  • an embodiment of the present application provides a device for controlling vehicle stability, including at least one processing element and at least one storage element, wherein the at least one storage element is used for storing programs and data, and the at least one processing element is used for Perform the method provided in the first aspect of this application.
  • the embodiments of the present application also provide a computer program, which when the computer program runs on a computer, causes the computer to execute the method provided in the first aspect.
  • the embodiments of the present application also provide a computer storage medium in which a computer program is stored.
  • the computer program is executed by a computer, the computer is caused to execute the method provided in the first aspect. .
  • an embodiment of the present application also provides a chip, which is used to read a computer program stored in a memory and execute the method provided in the above-mentioned first aspect.
  • an embodiment of the present application also provides a chip system, which includes a processor, and is configured to support a computer device to implement the method provided in the first aspect.
  • the chip system further includes a memory, and the memory is used to store necessary programs and data of the computer device.
  • the chip system can be composed of chips, or can include chips and other discrete devices.
  • FIG. 1 is a schematic diagram of a vehicle steering characteristic provided by an embodiment of the application
  • FIG. 2 is a schematic diagram of comparison of different drive architectures provided by the embodiments of the application.
  • FIG. 3 is a schematic diagram of a two-degree-of-freedom vehicle model provided by an embodiment of the application.
  • FIG. 4 is a schematic diagram of the corresponding relationship between the yaw moment and the lateral force of the two-degree-of-freedom vehicle model provided by an embodiment of the application;
  • FIG. 5 is a schematic diagram of a function curve of a lateral adhesion coefficient provided by an embodiment of the application.
  • FIG. 6 is a system architecture diagram of a front and rear axle distributed drive vehicle provided by an embodiment of the application.
  • FIG. 7 is a flowchart of a method for controlling vehicle stability according to an embodiment of the application.
  • FIG. 8 is a schematic structural diagram of a device for controlling vehicle stability according to an embodiment of the application.
  • FIG. 9 is a schematic structural diagram of yet another device for controlling vehicle stability according to an embodiment of the application.
  • FIG. 10 is a schematic structural diagram of another device for controlling vehicle stability according to an embodiment of the application.
  • the present application provides a method and equipment for controlling vehicle stability, which are used to provide an additional yaw moment to maintain vehicle stability for front and rear axle distributed drive electric vehicles by controlling wheel slip rate, so as to control the front and rear axle distributed drive vehicles. Lateral stability.
  • the method and the device are based on the same technical idea. Since the principles of the method and the device to solve the problem are similar, the implementation of the device and the method can be referred to each other, and the repetition will not be repeated.
  • the working condition of the vehicle that is, the working condition of the vehicle, can also be called the steering characteristics of the vehicle, which can be divided into three types: neutral steering, under-steer, and over-steer.
  • neutral steering refers to steering under a constant radius, and the steering angle does not require changes when the vehicle speed changes.
  • Understeer refers to steering under a constant radius, and the steering angle gradually increases with the increase of vehicle speed. Therefore, when a vehicle with a higher speed is turning, the driving trajectory will be deflected due to the larger steering angle, as shown by the dotted line on the left in Figure 1.
  • Excessive steering refers to steering at a constant radius, and the steering angle gradually decreases with the increase of vehicle speed. Therefore, when a vehicle with a higher speed is turning, the driving trajectory is deflected inward due to the smaller steering angle, as shown in the dotted line on the right in Figure 1. Shown.
  • the state of the vehicle is divided into two types: unstable and stable. Generally, the state of the vehicle can be judged by the angular velocity error between the actual yaw rate of the vehicle and the target yaw rate used to characterize the driver's desired trajectory.
  • the state of the vehicle is unstable.
  • the state of the vehicle is stable. Specifically as shown in the following formula:
  • e ⁇ is the angular velocity error
  • thd1 is the first threshold
  • thd1 is a positive number
  • thd2 is the second threshold
  • thd2 is a negative number
  • the angular velocity error between the actual yaw rate and the target yaw rate is used to determine whether the actual state of the vehicle meets the driver's desired state, that is, whether the state of the vehicle is unstable.
  • the angular velocity error can be determined using the following formula:
  • e ⁇ is the angular velocity error
  • is the actual yaw angular velocity
  • ⁇ d is the target yaw angular velocity
  • the front and rear axle distributed drive vehicles are proposed relative to the traditional centralized drive vehicle architecture.
  • the front and rear axle distributed drive vehicles have a set of drive systems on the front axle and the rear axle. The two systems are coupled through control instead of A special mechanical structure is required for hardware connection.
  • front and rear axle distributed drive vehicles can freely switch between front drive, rear drive and four-wheel drive. When four-wheel drive mode is adopted, it can independently, accurately and quickly control the drive/brake rotation of the motor. Torque makes the torque distribution ratio of the front and rear axles more free. Therefore, this drive architecture provides greater control freedom for the economy, power, maneuverability and stability of the vehicle.
  • this drive architecture provides greater control freedom for the economy, power, maneuverability and stability of the vehicle.
  • many vehicle manufacturers use this drive architecture to manufacture vehicles.
  • the two-degree-of-freedom vehicle model is a simplification of the entire vehicle model under the assumption that the longitudinal speed of the vehicle is uniform. Among them, the two degrees of freedom involved are the lateral (ie lateral) movement of the vehicle and the yaw movement of the vehicle.
  • the simplified process and coordinate system definition are shown in Figure 3.
  • the black dots in the figure represent the center of mass of the vehicle, and the squares represent the wheels.
  • is the steering angle of the wheels of the vehicle
  • v x is the longitudinal vehicle speed
  • v y is the lateral vehicle speed
  • is the yaw rate of the vehicle.
  • v x (m/s) is the longitudinal speed of the vehicle
  • v y (m/s) is the lateral speed of the vehicle
  • the longitudinal speed v x is a constant value and the lateral speed v y is a variable
  • k f (N /rad) are the equivalent cornering stiffnesses of the front and rear wheels, determined by the tire’s own characteristics
  • l f (m) and l r (m) are the center of mass to the front axle
  • the distance of the rear axle, m (kg) is the mass of the vehicle.
  • brackets in the above parameters are the units of the corresponding parameters.
  • the formula (5) can be defined Is the steering characteristic factor K. It should be noted that when the vehicle is fixed, the parameters related to K are all fixed parameters, that is, the vehicle is fixed, and its K is also a fixed constant. Therefore, an on-board processor capable of controlling vehicle stability The value of K can be stored, so that it can be used directly when calculating the target yaw rate, which improves the calculation efficiency.
  • the formula (6) for calculating the target yaw rate can be obtained through the two-degree-of-freedom vehicle model.
  • the corresponding relationship between the yaw moment and the steering angle of the vehicle, the lateral force of the front axle (the tire), and the lateral force of the rear axle (the tire) can be determined by the above two-degree-of-freedom vehicle model.
  • the positive yaw moment generated by the front axle lateral force relative to the center of mass is cos ⁇ F yf l f
  • the rear axle lateral force relative to the negative yaw moment generated by the center of mass -F yr l r therefore,
  • the yaw moment of the vehicle is the sum of the above positive yaw moment and negative yaw moment, as shown in formula (7):
  • the corresponding relationship can be determined by linearizing the relationship between the lateral force and the yaw rate (that is, the locally linearized tire model), which specifically includes the following steps:
  • the wheel lateral force F y (N) is usually determined by the wheel slip rate ⁇ (-), the wheel slip angle ⁇ (deg) and the wheel vertical force F z (N). Note that the brackets in the above parameters are the units of the corresponding parameters.
  • ⁇ y (-) is the lateral adhesion coefficient, which is a non-linear function of wheel slip rate ⁇ and wheel side slip angle ⁇ , and its non-linear function relationship is shown in Figure 5.
  • C 1 and C 0 are linearization coefficients.
  • the wheel slip rate is divided into two working conditions: driving condition and braking condition, then the wheel slip rate is defined as formula (10):
  • the tire linearization model can finally be expressed as formula (11):
  • C 1f and C 0f are the linearization coefficients of the front axle equivalent tire model
  • ⁇ fd is the equivalent front axle slip rate
  • ⁇ f is the front axle side slip angle
  • ⁇ 1 is the left front wheel slip angle
  • ⁇ 2 is the right front wheel slip angle
  • F zf is the front axle vertical force
  • F zf F z1 + F z2
  • F z1 is the left front wheel vertical force
  • F z2 is the right front wheel Vertical force.
  • C 1r and C 0r are the linearization coefficients of the equivalent rear axle tire model
  • ⁇ rd is the equivalent rear axle slip rate
  • ⁇ r is the rear axle slip angle
  • ⁇ 3 is the left rear wheel slip angle
  • ⁇ 4 is the right rear wheel slip angle
  • F zr is the rear axle vertical force
  • F zr F z3 +F z4
  • F z3 is the left rear wheel vertical force
  • F z4 It is the vertical force of the right rear wheel.
  • the method for controlling vehicle stability can be applied to a front and rear axle distributed drive vehicle. Specifically, the method for controlling vehicle stability can be carried on a separate vehicle-mounted electronic device (also referred to as controlling vehicle stability). It may be coupled to traditional vehicle stability control systems such as ESP and vehicle braking systems, which is not limited in this application.
  • ESP vehicle stability control systems
  • the vehicle may include: on-board sensors, driver input devices, advanced driver assistance system (ADAS), vehicle controllers, torque execution Unit and so on.
  • ADAS advanced driver assistance system
  • vehicle controllers torque execution Unit and so on.
  • the vehicle sensor is used to collect longitudinal acceleration a x (m/s 2 ), lateral acceleration a y (m/s 2 ), yaw rate ⁇ (rad/s), wheel speed ⁇ i ( rad/s) and other parameters.
  • i 1, 2, 3, 4, which respectively represent the front left vehicle, the front right vehicle, the rear left vehicle, and the rear right wheel.
  • the unit of the corresponding parameter is in the brackets of the above parameters.
  • the driver input device is used in manual driving scenarios, which can include steering wheel, accelerator pedal and brake pedal, manual gear lever, automatic gear controller, etc., to receive the driver's driving intention and generate corresponding data. For example, after the driver operates the steering wheel, the steering wheel will get the steering wheel angle ⁇ SW (rad).
  • the vehicle controller has a dynamics control function, which can control the driving and stability of the vehicle. Further, the vehicle controller may include a dynamics control function unit for executing the method for controlling vehicle stability provided in the embodiments of the present application.
  • the number of the motor control units may be one or two.
  • the motor control unit can control the front axle motor and the rear axle motor.
  • different motor control units can control different motors respectively.
  • the system architecture shown in FIG. 6 does not constitute a limitation on the front and rear axle distributed drive vehicles applicable to the embodiments of the present application, and the front and rear axle distributed drive vehicles may include more or fewer components.
  • the current rear axle distributed drive vehicle does not have an automatic driving function, it does not contain ADAS.
  • the driver's input device is not included inside.
  • the current rear axle distributed drive vehicle has both automatic driving function and manual driving function, it contains ADAS and driver input devices.
  • the parameters that can be changed in real time can be recorded as a function with time t as a variable, and t can represent the current time.
  • the parameters calculated or estimated based on the function with t as the variable are also recorded as the function with t as the variable.
  • the longitudinal acceleration, lateral acceleration, yaw rate, wheel speed, and steering wheel output angle measured by the on-board sensor can be denoted as a x (t), a y ( t), ⁇ (t), ⁇ i (t), ⁇ SW (t).
  • the wheel steering angle calculated by the steering wheel angle or output by ADAS is recorded as ⁇ (t).
  • ⁇ (t) ⁇ SW (t)/I s , where I s is the vehicle steering ratio, which is a fixed value.
  • the embodiment of the application provides a method for controlling the stability of a vehicle, and the method is suitable for the front and rear axle distributed drive vehicle shown in FIG. 6.
  • the method is executed by a device that controls the stability of the vehicle.
  • the device for controlling vehicle stability may be a vehicle controller, or an independent electronic device independent of the vehicle controller, or various on-board equipment coupled with vehicle stability control functions.
  • the device for controlling the stability of the vehicle may be referred to as an electronic device for short.
  • the vehicle may adopt any driving mode of front drive, rear drive, four-wheel drive with the best power, and four-wheel drive with the best effect, which is not limited in the present application.
  • the method specifically includes the following steps:
  • the electronic device may also use multiple methods to determine the state of the vehicle during the driving process of the vehicle, and the following methods may be used but not limited to:
  • the electronic device can obtain the driving parameters of the vehicle, such as longitudinal vehicle speed, lateral vehicle speed, side slip angle of the vehicle's center of mass, longitudinal acceleration, lateral acceleration, etc., and determine the vehicle by analyzing the above parameters status.
  • driving parameters of the vehicle such as longitudinal vehicle speed, lateral vehicle speed, side slip angle of the vehicle's center of mass, longitudinal acceleration, lateral acceleration, etc.
  • Method 2 Because the actual yaw rate of the vehicle can represent the actual trajectory of the vehicle without changing the working conditions of the vehicle, and the target yaw rate of the vehicle can represent the desired trajectory of the driver.
  • the state of the vehicle can be determined by the angular velocity error between the actual yaw rate of the vehicle and the target yaw rate. It can include the following steps:
  • the electronic device obtains the longitudinal speed, wheel steering angle, and actual yaw rate of the vehicle at the current moment.
  • the electronic device may collect the longitudinal acceleration a x (t), lateral acceleration a y (t), wheel speed ⁇ i (t), and actual yaw rate ⁇ of the vehicle at the current moment through the vehicle-mounted sensor. (t).
  • the electronic device can also obtain the steering wheel angle ⁇ SW (t) from the current steering wheel, and then obtain the wheel steering angle ⁇ (t) through ⁇ SW (t)/I s , where: wherein I s is the ratio of a vehicle steering, a fixed value; when the vehicle is driving automatically, the electronic device may acquire the steering wheel angle ⁇ (t) from the ADAS.
  • the electronic device may adopt a traditional longitudinal vehicle speed estimation method, and calculate according to the longitudinal acceleration a x (t), lateral acceleration a y (t), wheel speed ⁇ i (t), and actual yaw rate ⁇ (t) The longitudinal speed of the vehicle at the current moment v x (t).
  • the electronic device determines a target yaw rate based on the longitudinal vehicle speed, the steering angle of the wheels, and the stored steering characteristic factor.
  • the target yaw rate conforms to the following formula:
  • K is obtained by constructing a two-degree-of-freedom vehicle model for the vehicle.
  • m is the mass of the vehicle
  • k f and k r are the equivalent cornering stiffnesses of the front wheels and the rear wheels, respectively, which are determined by the characteristics of the tires of the vehicle.
  • the electronic device may also perform saturation processing on the target yaw rate.
  • the electronic device calculates an angular velocity error between the actual yaw rate and the target yaw rate.
  • the angular velocity error e ⁇ (t) conforms to the following formula:
  • the vehicle-mounted sensor will be interfered by the outside world during the driving of the vehicle, there will be errors in the collected data.
  • the target yaw rate calculated by the two-degree-of-freedom vehicle model will also have errors, although each error is relatively high. Small can be ignored, but when the error accumulates, it will affect the final judgment result of the electronic device. Therefore, it is necessary to set a certain threshold to judge the state of the vehicle.
  • the electronic device determines that the angular velocity error does not fall within the threshold interval formed by the first threshold and the second threshold, it determines that the state of the vehicle is unstable, wherein the first threshold is a positive number, The second threshold is a negative number.
  • step A4 the electronic device may determine the state of the vehicle through the judgment method shown in the following formula:
  • thd1 is the first threshold, and thd1 is a positive number, thd2 is the second threshold, and thd2 is a negative number.
  • step S701 when the electronic device executes the above step S701, it can obtain the actual front axle slip rate ⁇ f (t) and the rear axle actual slip rate ⁇ f of the vehicle at the current time through the following steps (t):
  • the electronic device obtains the current longitudinal acceleration a x (t), lateral acceleration a y (t), wheel speed ⁇ i (t), and actual yaw rate ⁇ (t), wheel steering angle ⁇ ( t), the specific process can refer to the above step A1.
  • the electronic device may output according to the opening of the accelerator pedal and the brake pedal in the driver input device, and the manual gear rocker and/or the automatic gear controller.
  • the initial torque T f0 of the front axle and the initial torque T r0 of the rear axle are calculated.
  • the electronic device may calculate the initial torque T f0 of the front axle and the initial torque T r0 of the rear axle according to the braking or driving demand output by the ADAS.
  • the electronic device may obtain the required yaw moment M(t) of the vehicle through the following steps when performing step S701:
  • the electronic device obtains the angular velocity error between the actual yaw rate and the target yaw rate.
  • the electronic device may directly use the angular velocity error calculated in step A3.
  • the electronic device determines the required yaw moment according to the acquired angular velocity error.
  • the required yaw moment conforms to the following formula:
  • the required yaw moment conforms to the following formula:
  • M(t) is the required yaw moment
  • sign( ⁇ (t)) is a sign function
  • ⁇ (t) is the steering angle of the wheel
  • e ⁇ (t) is the actual yaw rate and The difference between the target yaw rate
  • K Po is the proportional module gain coefficient of the vehicle in excessive steering conditions
  • K Io is the integral module gain coefficient of the vehicle in excessive steering conditions
  • K Do The differential module gain coefficient of the vehicle in an over-steering condition
  • t 0 is the moment when the state of the vehicle is unstable
  • t is the current moment
  • K Pu is the proportional module gain of the vehicle in an under-steering condition
  • the coefficient is the gain coefficient of the integral module of the vehicle in the under-steer condition of K Iu, and the gain coefficient of the differential module of the vehicle in the under-steer condition of the K Du .
  • the electronic device determines the corresponding relationship between the yaw moment and the slip rate of the front axle and the slip rate of the rear axle.
  • the corresponding relationship between the yaw moment and the slip rate of the front axle and the slip rate of the rear axle is stored internally in the electronic device.
  • the corresponding relationship between the yaw moment and the slip rate of the front axle and the slip rate of the rear axle is determined by the electronic device according to the current driving situation of the vehicle.
  • formula (12) and formula (13) can be substituted into formula (7) to obtain the target correspondence, that is, yaw moment and front axle slip rate, rear axle
  • the slip rate, and the corresponding relationship between the vehicle steering angle, front axle slip angle, rear axle slip angle, front axle vertical force, and rear axle vertical force are shown in the following formula:
  • M is the yaw moment
  • is the wheel steering angle
  • C 1f and C 0f are the linearization coefficients of the front axle equivalent tire model
  • C 1r and C 0r are the rear axle equivalent tire linearization factors
  • ⁇ fd is the front axle Equivalent slip rate
  • ⁇ rd is the equivalent slip rate of the rear axle
  • ⁇ f is the side slip angle of the front axle
  • ⁇ r is the side slip angle of the rear axle
  • F zf is the front axle vertical force
  • F zr is the rear axle vertical
  • l f is the distance from the center of mass of the vehicle to the front axle
  • l r is the distance from the center of mass of the vehicle to the rear axle.
  • the values of other parameters except M, ⁇ fd and ⁇ rd can be determined by the electronic device.
  • is the wheel steering angle ⁇ (t) at the current moment obtained by the electronic device
  • ⁇ f is the front axle side slip angle calculated at the current moment by the electronic device
  • ⁇ r is the side slip angle of the rear axle calculated at the current moment
  • F zf is the front axle vertical force
  • F zf (t) F z1 (t) + F z2 (t) calculated at the current moment of the electronic device
  • F zr is the rear axle vertical force calculated at the current moment of the electronic device
  • F zr (t) F z3 (t) + F z4 (t)
  • ⁇ i (t) is the side slip angle of each wheel at the current moment
  • F zi (t) is the vertical force of each wheel at the current moment
  • ⁇ i (t) is determined by the electronic device according to the centroid side slip angle according to the existing calculation method, and the centroid side slip angle may be the longitudinal acceleration a of the electronic device according to the current moment of the vehicle.
  • x (t) lateral acceleration a y (t), wheel speed ⁇ i (t), actual yaw rate ⁇ (t), wheel steering angle ⁇ (t) and other parameters are estimated.
  • F zi (t) is also estimated by the electronic device according to the existing calculation method, based on the aforementioned parameters, the braking or driving requirements of the vehicle, and the mass, l f , l r, etc. of the vehicle.
  • the electronic device can obtain the values of other parameters except M, ⁇ fd , and ⁇ rd in formula (14) and substitute them into formula (14).
  • the electronic device can establish the yaw moment and front axle slip Corresponding relationship between rate and rear axle slip rate.
  • the electronic device determines the front axle target slip rate and the rear axle target slip rate according to the determined correspondence between the yaw moment, the front axle slip rate, and the rear axle slip rate, and the required yaw moment. Shift rate.
  • step B1 the electronic device can substitute the required yaw moment M(t) obtained in S701 into formula (14), and a constraint equation for the front axle slip rate and the rear axle slip rate can be obtained. Since the front and rear slip rate and the rear axle slip rate in the constraint equation are both absolute values, multiple slip rate combinations can be obtained by solving the above constraint equation.
  • the electronic device selects at least one slip rate combination in which the front axle slip rate and the rear axle slip rate are less than 0 among the multiple slip rate combinations.
  • the current vehicle may be in the driving mode or the braking mode
  • the vehicle since the vehicle is unstable at the current moment, in order to ensure driving safety, it is generally necessary to brake the vehicle. Quickly ensure the stability of the vehicle.
  • the front axle slip rate and the rear axle slip rate of the vehicle are both less than zero.
  • the electronic device selects the target slip rate combination with the smallest sum of the absolute value of the front axle slip rate and the absolute value of the rear axle slip rate from the at least one slip rate combination.
  • the electronic device may select the target slip with the smallest sum of the absolute value of the front axle slip rate and the absolute value of the rear axle slip rate from the at least one slip rate combination. Shift rate combination.
  • the electronic device determines that the front axle slip rate in the target slip rate combination is the front axle target slip rate, and determines that the rear axle slip rate in the target slip rate combination is the Target slip rate of the rear axle.
  • the electronic device can quickly and accurately obtain the front axle target slip rate ⁇ fd (t) and the rear axle target slip rate ⁇ in accordance with the current driving situation under the premise of ensuring the safety of the vehicle. rd (t).
  • the electronic device determines the front axle target torque according to the difference between the front axle target slip rate and the front axle actual slip rate, and the front axle initial torque; and according to the rear axle target slip The difference between the shift rate and the actual slip rate of the rear axle, and the initial torque of the rear axle, determine the target torque of the rear axle.
  • the front axle target torque conforms to the following formula:
  • the target rear axle torque conforms to the following formula:
  • T f (t) is the front axle target torque
  • T f0 is the front axle initial torque
  • T r (t) is the target torque of the rear axle
  • T r0 is the initial torque of the rear axle
  • K P is the gain coefficient of the proportional module
  • K I I is the gain coefficient of the integral module
  • K D is the gain coefficient of the differential module
  • t 0 is the moment when the state of the vehicle is unstable
  • t is the current moment.
  • S705 The electronic device performs stability control on the vehicle according to the front axle target torque and the rear axle target torque.
  • the electronic device may be a front axle of the target torque T f (t) and the target axle torque T r (t) transmitted to the vehicle torque executing unit, so that,
  • the torque execution unit may control the front axle motor according to the front axle target torque T f (t), and control the rear axle motor according to the rear axle target torque T r (t) to make the front axle motor
  • the axle motor and the rear axle motor apply corresponding target torques to the front axle and the rear axle, respectively, so as to realize the stability control of the vehicle, thereby ensuring the stability and safety of the vehicle.
  • the control response is faster, so the convergence speed of the yaw rate of the vehicle is faster, and thus The time for the vehicle to enter the stable state from the unstable state is shorter, so that the safety of the vehicle can be further ensured.
  • the embodiment of the present application provides a method for controlling the stability of a vehicle.
  • the electronic device can obtain the actual slip rate of the front axle and the actual slip rate of the rear axle when determining the vehicle instability, and then quickly and accurately Obtain the front axle target slip rate and the rear axle target slip rate that conform to the current driving situation, and then the difference between the front axle target slip rate and the front axle actual slip rate, and the rear axle target
  • the difference between the slip rate and the actual slip rate of the rear axle determines the target torque of the front axle and the target torque of the rear axle that can ensure the stability of the vehicle, so that the stability of the vehicle can be controlled.
  • the method takes into account the yaw motion of the vehicle, and provides the vehicle with additional yaw moment that maintains the lateral stability of the vehicle through the compensation of the front and rear axle slip rate, thereby controlling the lateral stability of the vehicle and improving the driving process of the vehicle In the stability.
  • the front axle target slip rate and the rear axle target slip rate are obtained according to the vehicle's required yaw moment at the current moment, the real-time calculated front axle target slip rate and the rear axle target slip rate are more consistent with The driving situation of the vehicle at the current moment, that is, no matter what driving mode the vehicle is in the stability control enable, the stability of the vehicle can be quickly and accurately ensured by this method.
  • the method establishes the corresponding relationship between the yaw moment and the slip rate of the front axle and the slip rate of the rear axle through the two-degree-of-freedom vehicle model and the partially linearized tire model, so that the electronic device can obtain the more accurate information in real time.
  • the target slip rate of the front axle and the target slip rate of the rear axle that conform to the driving situation of the vehicle at the current moment, so that the vehicle can be controlled in real time.
  • the embodiments of the present application also provide a device for controlling vehicle stability.
  • the device is suitable for the front and rear axle distributed drive vehicle shown in FIG. 6 and is used to implement the above method for controlling vehicle stability.
  • the device may be a vehicle controller, an independent electronic device independent of the vehicle controller, or various vehicle-mounted devices coupled with vehicle stability control functions.
  • the device is connected with on-board sensors, driver input devices, ADAS, and torque execution units through a bus.
  • the device can obtain the longitudinal acceleration, lateral acceleration, wheel speed, and actual yaw rate of the vehicle at the current moment from the vehicle-mounted transmitter.
  • the device can obtain the steering wheel angle, accelerator pedal opening, brake pedal opening, and gear position from the driver input device.
  • the device can obtain wheel steering angle and braking or driving requirements from the ADAS.
  • the device executes the method of controlling vehicle stability and obtains the target torque of the front axle and the target torque of the rear axle, it can be sent to the torque execution unit, so that the torque execution unit controls the front axle motor and the rear axle motor, thereby Apply braking or driving torque to the front and rear axles, and finally realize the control of vehicle maneuverability and stability.
  • the data processing module is used to receive raw data sent by vehicle sensors, driver input devices, and ADAS, and calculate or estimate other related parameters based on the received raw data, as shown in FIG. 8.
  • the data processing module may use a traditional longitudinal vehicle speed estimation method to calculate the longitudinal vehicle speed of the vehicle at the current moment based on the longitudinal acceleration, lateral acceleration, wheel speed, and actual yaw rate.
  • the data processing module calculates the side slip angle of the center of mass of the wheel based on the longitudinal acceleration, lateral acceleration, wheel speed, and actual yaw rate, wheel steering angle, and estimates the side slip angle of each wheel based on the center of mass side slip angle. Slip angle.
  • the data processing module is based on longitudinal acceleration, lateral acceleration, wheel speed, actual yaw rate, wheel steering angle, braking or driving requirements of the vehicle, as well as the vehicle's mass, l f , l r, etc., Estimate the vertical force of each wheel.
  • the data processing module calculates the actual slip rate of each wheel based on the longitudinal vehicle speed and wheel speed.
  • the target yaw rate calculation module is used to calculate the target yaw rate based on the steering angle of the wheels and the longitudinal vehicle speed.
  • the target yaw rate conforms to the following formula:
  • ⁇ d (t) is the target yaw rate
  • v x (t) is the longitudinal vehicle speed
  • ⁇ (t) is the steering angle of the wheels
  • l f is the distance from the center of mass of the vehicle to the front axle
  • L r is the distance from the center of mass of the vehicle to the rear axle
  • K is the steering characteristic factor
  • t is the current time.
  • the state determining module of the vehicle is used to determine the state of the vehicle.
  • the state determining module of the vehicle may be implemented in multiple methods.
  • the state determining module of the vehicle may analyze the vehicle's state according to longitudinal vehicle speed, lateral vehicle speed, sideways angle of the center of mass, longitudinal acceleration, and lateral acceleration.
  • the state determining module of the vehicle may determine the state of the vehicle according to the angular velocity error between the actual yaw rate and the target yaw rate.
  • the angular velocity error conforms to the following formula:
  • e ⁇ (t) is the angular velocity error
  • ⁇ (t) is the actual yaw angular velocity
  • ⁇ d (t) is the target yaw angular velocity
  • thd1 is the first threshold, and thd1 is a positive number, thd2 is the second threshold, and thd2 is a negative number.
  • the required yaw moment calculation module is used to calculate the required yaw moment when the state determination module of the vehicle determines that the vehicle is unstable.
  • the required yaw moment is calculated according to the angular velocity error and the wheel steering angle.
  • the required yaw moment conforms to the following formula:
  • the front axle slip angle and the rear axle slip angle calculation module are used to calculate the front axle slip angle and the rear axle slip angle according to the slip angles of the four wheels, where the front axle slip angle Side slip angle of rear axle ⁇ i (t) is the slip angle of each wheel at the current moment.
  • M is the yaw moment
  • is the wheel steering angle
  • C 1f and C 0f are the linearization coefficients of the front axle equivalent tire model
  • C 1r and C 0r are the rear axle equivalent tire linearization factors
  • ⁇ fd is the front axle Equivalent slip rate
  • ⁇ rd is the equivalent slip rate of the rear axle
  • ⁇ f is the side slip angle of the front axle
  • ⁇ r is the side slip angle of the rear axle
  • F zf is the front axle vertical force
  • F zr is the rear axle vertical
  • l f is the distance from the center of mass of the vehicle to the front axle
  • l r is the distance from the center of mass of the vehicle to the rear axle.
  • the front axle target slip rate and rear axle target slip rate calculation module calculates the front axle slip rate and rear axle slip rate according to the required yaw moment and the corresponding relationship between the yaw moment and the front axle slip rate and rear axle slip rate. Axle target slip rate and rear axle target slip rate.
  • the calculation module for the actual slip rate of the front axle and the actual slip rate of the rear axle is used to calculate the actual slip rate of the front axle and the actual slip rate of the rear axle according to the actual slip rates of the four wheels.
  • the actual slip rate of the front axle ⁇ f (t) ⁇ 1 (t) + ⁇ 2 (t)
  • the actual slip rate of the rear axle ⁇ r (t) ⁇ 3 (t) + ⁇ 4 (t) .
  • ⁇ i (t) is the actual slip rate of each wheel at the current moment.
  • the calculation module for the initial torque of the front axle and the initial torque of the rear axle is used in a manual driving scenario, and the electronic equipment can be based on the opening of the accelerator pedal and the brake pedal output by the driver input device, and the manual gear rocker And/or the gear output by the automatic gear controller, according to the power optimization or energy optimization method, the initial torque T f0 of the front axle and the initial torque T r0 of the rear axle are calculated.
  • the electronic device can calculate the initial torque T f0 of the front axle and the initial torque T r0 of the rear axle according to the braking or driving demand output by the ADAS.
  • the front axle target torque and rear axle target torque calculation modules are used to obtain the difference e ⁇ f (t) between the front axle target slip rate and the front axle actual slip rate, and then according to e ⁇ f (t) And the initial torque of the front axle, the formula Obtain the front axle target torque; and obtain the difference e ⁇ r (t) between the rear axle target slip rate and the rear axle actual slip rate, and then according to e ⁇ r (t) and the rear axle initial torque, the formula Get the rear axle torque.
  • T f (t) is the front axle target torque
  • T f0 is the front axle initial torque
  • T r (t) is the target torque of the rear axle
  • T r0 is the initial torque of the rear axle
  • K P is the gain coefficient of the proportional module
  • K I I is the gain coefficient of the integral module
  • K D is the gain coefficient of the differential module
  • t 0 is the moment when the state of the vehicle is unstable
  • t is the current moment.
  • the embodiments of the present application also provide a device for controlling the stability of a vehicle.
  • the device is suitable for the front and rear axle distributed drive vehicle shown in FIG. 6 and is used to implement the above method for controlling the stability of the vehicle.
  • Figure 8 shows the function of the device.
  • the device 900 includes: an acquisition unit 901, a determination unit 902, a torque calculation unit 903, and a stability control unit 904. The following describes the functions of each unit of the device 900 during vehicle stability control.
  • the obtaining unit 901 is used to obtain the required yaw moment, the actual slip rate of the front axle, the actual slip rate of the rear axle, the initial torque of the front axle and the initial initial torque of the rear axle of the vehicle at the current moment when the state of the vehicle is unstable Torque
  • the determining unit 902 is used to determine the corresponding relationship between the yaw moment and the front axle slip rate and the rear axle slip rate of the vehicle; and according to the determined yaw moment and the front axle slip rate and the rear axle slip The corresponding relationship between the ratio and the required yaw moment, determine the target slip ratio of the front axle and the target slip ratio of the rear axle;
  • the preset threshold interval is an interval formed by the first threshold and the second threshold, wherein, The first threshold is a positive number, and the second threshold is a negative number.
  • the target yaw rate conforms to the following formula:
  • the angular velocity error conforms to the following formula:
  • e ⁇ (t) is the angular velocity error
  • ⁇ (t) is the actual yaw angular velocity
  • ⁇ d (t) is the target yaw angular velocity
  • the determining unit 902 may determine the corresponding relationship between the yaw moment, the front axle slip rate, and the rear axle slip rate through the following steps:
  • M is the yaw moment
  • is the wheel steering angle
  • C 1f and C 0f are the linearization coefficients of the front axle equivalent tire model
  • C 1r and C 0r are the rear axle equivalent tire linearization factors
  • ⁇ fd is the front axle Slip rate
  • ⁇ rd is the rear axle slip rate
  • ⁇ f is the front axle side slip angle
  • ⁇ r is the rear axle side slip angle
  • F zf is the front axle vertical force
  • F zr is the rear axle vertical force
  • l f is the distance from the center of mass of the vehicle to the front axle
  • l r is the distance from the center of mass of the vehicle to the rear axle.
  • the determining unit 902 may determine the corresponding relationship between the yaw moment, the front axle slip rate, the rear axle slip rate, and the required yaw moment through the following steps Front axle target slip rate and rear axle target slip rate:
  • the front axle target torque complies with the following formula:
  • the target rear axle torque conforms to the following formula:
  • the device takes into account the yaw motion of the vehicle, and compensates for the slip ratio of the front and rear axles to provide the vehicle with additional yaw moment that maintains the lateral stability of the vehicle, thereby controlling the lateral stability of the vehicle and improving the vehicle's driving process The stability.
  • the front axle target slip rate and the rear axle target slip rate are obtained according to the vehicle's required yaw moment at the current moment, the real-time calculated front axle target slip rate and the rear axle target slip rate are more consistent with The driving situation of the vehicle at the current moment, that is, regardless of the driving mode of the vehicle in the stability control enable, the device can quickly and accurately ensure the stability of the vehicle.
  • each functional unit in each embodiment of this application It can be integrated into one processing unit, or it can exist alone physically, or two or more units can be integrated into one unit.
  • the above-mentioned integrated unit can be implemented in the form of hardware or software functional unit.
  • the embodiments of the present application also provide a device for controlling the stability of a vehicle.
  • the device is suitable for the front and rear axle distributed drive vehicle shown in FIG. 6 and is used to implement the above method for controlling the stability of the vehicle.
  • Figure 8 and Figure 9 show the function of the device.
  • the device 1000 includes: a communication interface 1001, a processor 1002, and a memory 1003.
  • the communication interface 1001 is used to communicate with other components in the vehicle.
  • the communication interface 1001 obtains various data from components such as on-board sensors, driver input devices, and ADAS.
  • the communication interface 1001 sends the calculated front axle target torque and the rear axle target torque to the torque execution unit for the final vehicle stability control.
  • the embodiments of the present application also provide a computer storage medium in which a computer program is stored.
  • the computer program executes the method provided in the above embodiment.
  • an embodiment of the present application also provides a chip, which is used to read a computer program stored in a memory to implement the method provided in the above embodiment.

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Abstract

一种控制车辆稳定性的方法及设备,该方法可以应用于智能驾驶/自动驾驶等智能汽车领域,用于控制前后轴分布式驱动车辆的横向稳定性。该方法考虑到车辆的横摆运动,并且通过前后轴滑移率补偿的方式来为车辆提供额外维持车辆横向稳定性的横摆力矩,从而控制车辆的横向稳定性,进而提升车辆行驶过程中的稳定性。

Description

一种控制车辆稳定性的方法及设备
相关申请的交叉引用
本申请要求在2019年08月15日提交中国专利局、申请号为201910754641.9、申请名称为“一种控制车辆稳定性的方法及设备”的中国专利申请的优先权,其全部内容通过引用结合在本申请中。
技术领域
本申请涉及智能汽车技术领域,尤其涉及一种控制车辆稳定性的方法及设备。
背景技术
目前,车辆的车身电子稳定系统(electronic stability program,ESP)一般通过在车辆的左右轮上产生制动力矢量来控制产生附加横摆力矩,以提升车辆稳定性。例如,当车辆转向力不足时,车辆可以通过ESP在内后轮进行制动产生与转向方向相同的附加横摆力矩,以保证车辆稳定并按照驾驶员期望轨迹行驶,如图1中的左图所示。又例如,当车辆转向力过多时,车辆可以通过ESP在外前轮进行制动产生与转向方案相反的附加横摆力矩,以保证车辆稳定并按照驾驶员期望轨迹行驶,如图1中的右图所示。然而这种通过制动力介入产生横摆力矩以提高车辆稳定性的方法通常设置的介入较晚且制动介入较强烈,降低了驾驶员的使用体验。
相对于传统的集中式驱动车辆,前后轴分布式驱动车辆在前轴和后轴各有一套驱动系统,两个系统之间通过控制进行耦合。由于前后轴的扭矩分配比例更自由,因此,这种驱动架构为车辆的经济性、动力性、操纵性和稳定性等提供了更大的控制自由度。
特别地,前后轴扭矩的分配比例还会直接影响车轮的滑移率,进而影响车辆的转向特性和稳定性。因此,如何通过控制车轮滑移率来提供额外维持车辆稳定的横摆力矩在前后轴分布式驱动电动车辆实际工程应用中充满了挑战。
发明内容
本申请提供一种控制车辆稳定性的方法及设备,用于控制前后轴分布式驱动车辆的横向稳定性。
第一方面,本申请提供了一种控制车辆稳定性的方法,该方法可以适用于图6所示的前后轴分布式驱动车辆中,由控制车辆稳定性的设备(简称电子设备)执行。其中该方法具体包括以下步骤:
所述电子设备在车辆的状态为失稳时,获取当前时刻所述车辆的需求横摆力矩、前轴实际滑移率、后轴实际滑移率,以及前轴初始扭矩和后轴初始扭矩;然后,所述电子设备确定所述车辆的横摆力矩与前轴滑移率、后轴滑移率的对应关系,并根据确定的所述横摆力矩与前轴滑移率、后轴滑移率的对应关系,以及所述需求横摆力矩,确定前轴目标滑移率和后轴目标滑移率;之后,所述电子设备根据所述前轴目标滑移率和所述前轴实际滑移率的差值,以及所述前轴初始扭矩,确定前轴目标扭矩;并根据所述后轴目标滑移率和所述后轴实际滑移率的差值,以及所述后轴初始扭矩,确定后轴目标扭矩;最终所述电子设备可以根据所述前轴目标扭矩和所述后轴目标扭矩,对所述车辆进行稳定性控制。
在本方法中,电子设备在车辆失稳时,可以获取前轴实际滑移率和后轴实际滑移率,然后快速且准确地得到符合当前行驶情况的前轴目标滑移率和后轴目标滑移率,进而可以根据所述前轴目标滑移率和所述前轴实际滑移率的差值,以及所述后轴目标滑移率和所述 后轴实际滑移率的差值,确定能够保证所述车辆稳定的前轴目标扭矩和后轴目标扭矩,进而可以对车辆进行稳定性控制。该方法考虑到车辆的横摆运动,并且通过前后轴滑移率补偿的方式来为车辆提供额外维持车辆横向稳定性的横摆力矩,从而控制车辆的横向稳定性,进而提升车辆行驶过程中的稳定性。另外,由于所述前轴目标滑移率和后轴目标滑移率是根据当前时刻车辆的需求横摆力矩得到的,因此实时计算的前轴目标滑移率和后轴目标滑移率更符合当前时刻所述车辆的行驶情况,即无论所述车辆在稳定性控制使能是何种驱动方式,通过该方法均可以快速且准确地保证车辆的稳定性。
在一个可能的设计中,所述电子设备还可以但不限于通过以下方法,确定车辆的状态:
方法一:所述电子设备根据当前时刻所述车辆的实际横摆角速度和目标横摆角速度之间的角速度误差,确定车辆的状态;
方法二:所述电子设备可以根据所述车辆的行驶参数,例如纵向车速、横向车速、车辆的质心侧偏角、纵向加速度、侧向加速度等,并通过对以上参数进行分析,确定所述车辆的状态。
通过该设计,所述电子设备可以准确地确定所述车辆的状态。
在一个可能的设计中,所述电子设备可以通过以下步骤,根据所述车辆的实际横摆角速度和目标横摆角速度之间的角速度误差,确定车辆的状态:
所述电子设备获取所述当前时刻所述车辆的纵向车速、车轮转向角和实际横摆角速度;所述电子设备根据所述纵向车速、所述车轮转向角以及存储的转向特性因数,确定目标横摆角速度;所述电子设备计算所述实际横摆角速度与所述目标横摆角速度之间的角速度误差;当所述角速度误差未落入由第一阈值和第二阈值构成的阈值区间内时,确定所述车辆的状态为失稳;否则,确定所述车辆的状态为稳定。其中,所述实际横摆角速度能够表征在不改变车辆的工况情况下车辆实际的行驶轨迹,所述目标横摆角速度用于表征所述车辆的驾驶员的期望轨迹,所述第一阈值为正数,所述第二阈值为负数。
通过该设计,所述电子设备可以根据所述车辆的当前行驶情况,准确地确定所述车辆的状态。
在一个可能的设计中,所述目标横摆角速度符合以下公式:
Figure PCTCN2020080531-appb-000001
其中,γ d(t)为所述目标横摆角速度,v x(t)为所述纵向车速,δ(t)为所述车轮转向角,l f为所述车辆的质心到前轴的距离,l r为所述车辆的质心到后轴的距离,K为所述转向特性因数,t为当前时刻。
通过该设计,所述电子设备可以准确地计算所述车辆的目标横摆角速度。
在一个可能的设计中,所述电子设备可以根据所述角速度误差,确定所述需求横摆力矩。
示例性的,当所述角速度误差大于所述第一阈值时,所述需求横摆力矩符合以下公式:
Figure PCTCN2020080531-appb-000002
示例性的,当所述角速度误差小于所述第二阈值时,所述需求横摆力矩符合以下公式:
Figure PCTCN2020080531-appb-000003
其中,M(t)为所述需求横摆力矩,sign(δ(t))为符号函数,δ(t)为所述车轮转向角,e γ(t)为所述实际横摆角速度与所述目标横摆角速度的差值,K Po为所述车辆在过多转向工况时的比例模块增益系数,K Io为所述车辆在过多转向工况时的积分模块增益系数、K Do所述车辆在过多转向工况时的微分模块增益系数,t 0为所述车辆的状态为失稳的时刻,t为当前时刻,K Pu为所述车辆在不足转向工况时的比例模块增益系数,K Iu所述车辆在不足转向工况时的积分模块增益系数、K Du所述车辆在不足转向工况时的微分模块增益系数。
通过该设计,所述电子设备可以准确地计算出能够使所述车辆稳定的需求横摆力矩。
示例性的,所述角速度误差符合以下公式:
Figure PCTCN2020080531-appb-000004
其中,e γ(t)为所述角速度误差,γ(t)为所述实际横摆角速度,γ d(t)为所述目标横摆角速度。
在一个可能的设计中,所述电子设备可以通过以下步骤获取所述车辆当前时刻的前轴实际滑移率λ f(t)和后轴实际滑移率λ f(t):
首先所述电子设备获取车辆当前时刻的纵向加速度a x(t)、侧向加速度a y(t)、轮速ω i(t),以及实际横摆角速度γ(t),车轮转向角δ(t);然后所述电子设备根据以上参数,先计算纵向车速v x(t),然后根据纵向车速v x(t)和轮速ω i(t),按照传统的车轮滑移率计算方法,计算四个车轮的实际滑移率λ i(t),且i=1,2,3,4时分别代表左前车轮、右前车轮、左后车轮、右后车轮;最后,所述电子设备计算前轴实际滑移率λ f(t)=λ 1(t)+λ 2(t),以及计算后轴实际滑移率λ r(t)=λ 3(t)+λ 4(t)。
通过该设计,所述电子设备可以根据所述车辆当前的行驶情况,准确地确定前轴实际滑移率和后轴实际滑移率。
在一个可能的设计中,在人工驾驶场景下,所述电子设备可以根据驾驶员输入装置中油门踏板和制动踏板的开度,以及手动档位摇杆和/或自动档位控制器输出的档位,按照动力最优或者能量最优方法,计算得到前轴初始扭矩T f0和后轴初始扭矩T r0
通过该设计,所述电子设备可以根据驾驶员输入装置输出的数据,准确地计算前轴初始扭矩和后轴初始扭矩。
在一个可能的设计中,在自动驾驶场景下,所述电子设备可以根据ADAS输出的制动或驱动需求,计算得到前轴初始扭矩T f0和后轴初始扭矩T r0。通过该设计,所述电子设备可以在自动驾驶场景下,准确地计算前轴初始扭矩和后轴初始扭矩。
在一个可能的设计中,所述电子设备通过以下步骤,确定所述车辆的横摆力矩与前轴滑移率、后轴滑移率的对应关系,包括:
首先,所述电子设备获取所述当前时刻所述车辆的车轮转向角、前轴侧偏角、后轴侧偏角、前轴垂向力以及后轴垂向力;然后,根据所述车轮转向角、所述前轴侧偏角、所述后轴侧偏角、所述前轴垂向力以及所述后轴垂向力,以及存储的目标对应关系,建立所述横摆力矩与前轴滑移率、后轴滑移率的对应关系。其中,所述目标对应关系为根据前轴侧向力与前轴滑移率、前后侧偏角、前轴垂向力的对应关系,后轴侧向力与后轴滑移率、后轴侧偏角、后轴垂向力的对应关系,以及横摆力矩与车辆转向角、前轴侧向力、后轴侧向力的对应关系确定的。
其中,前轴侧向力与前轴滑移率、前轴侧偏角、前轴垂向力的对应关系,以及后轴侧向力与后轴滑移率、后轴侧偏角、后轴垂向力的对应关系,是根据侧向力与横摆角速度关系的线性化分析得到的。而横摆力矩与车辆转向角、前轴侧向力、后轴侧向力的对应关系是对两自由度车辆模型的分析确定的。因此通过该设计,所述电子设备可以准确地建立横摆力矩与前轴滑移率、后轴滑移率的对应关系。
示例性的,所述横摆力矩与前轴滑移率、后轴滑移率的对应关系符合以下公式:
M=cosδ(C 1ffd|+C 0ffF zfl f-(C 1rrd|+C 0rrF zrl r
其中,M为横摆力矩,δ为车轮转向角,C 1f和C 0f为前轴等效轮胎模型线性化系数,C 1r和C 0r为后轴等效轮胎线性化系数,λ fd为前轴滑移率,λ rd为后轴滑移率,α f为前轴侧偏角,α r为后轴侧偏角,F zf为前轴垂向力,F zr为后轴垂向力,l f为车辆的质心到前轴的距离,l r为车辆的质心到后轴的距离。
在一个可能的设计中,所述电子设备可以通过以下步骤,确定前轴目标滑移率和后轴目标滑移率:
首先,所述电子设备根据所述横摆力矩与前轴滑移率、后轴滑移率的对应关系,以及所述需求横摆力矩,确定多个滑移率组合,其中,每个滑移率组合包含一个前轴滑移率和一个后轴滑移率;之后,所述电子设备在所述多个滑移率组合中,选择前轴滑移率和后轴滑移率小于0的至少一个滑移率组合;然后,在所述至少一个滑移率组合中选择前轴滑移率的绝对值和后轴滑移率的绝对值之和最小的目标滑移率组合;最后,所述电子设备确定所述目标滑移率组合中的前轴滑移率为所述前轴目标滑移率,并确定所述目标滑移率组合中的后轴滑移率为所述后轴目标滑移率。
通过上述公式可知,所述电子设备根据所述横摆力矩与前轴滑移率、后轴滑移率的对应关系,以及所述需求横摆力矩,可以得到多组解,而且所述多个组解中数值有正值也有负值。并且我们知道,为了保证车辆的行驶安全,可以对车辆进行制动处理,在车辆处于制动模式下,车辆的滑移率小于0。我们还知道,车辆的滑移率的绝对值越小,制动效果越好。因此,为了在所述多组解中找到最优解,所述电子设备可以将前轴滑移率和后轴滑移率小于0,以及前轴滑移率的绝对值和后轴滑移率的绝对值之和最小,作为两个约束条件,这样所述电子设备最终得到的前轴目标滑移率和后轴目标滑移率可以保证车辆的行驶安全。
在一个可能的设计中,所述前轴目标扭矩符合以下公式:
Figure PCTCN2020080531-appb-000005
所述后轴目标扭矩符合以下公式:
Figure PCTCN2020080531-appb-000006
其中,T f(t)为所述前轴目标扭矩,T f0为所述前轴初始扭矩,e λf(t)为所述前轴目标滑移率和所述前轴实际滑移率的差值,T r(t)为所述后轴目标扭矩,T r0为所述后轴初始扭矩,e λr(t)为所述后轴目标滑移率和所述后轴实际滑移率的差值,K P为比例模块增益系数,K I为积分模块增益系数,K D为微分模块增益系数,t 0为所述车辆的状态为失稳的时刻,t为当前时刻。
通过该设计,所述电子设备可以准确地计算到前轴目标扭矩和后轴目标扭矩,从而可以根据所述前轴目标扭矩和所述后轴目标扭矩,对所述车辆进行稳定性控制。
第二方面,本申请实施例提供了一种控制车辆稳定性的设备,包括用于执行以上第一方面中各个步骤的单元。
第三方面,本申请实施例提供了一种控制车辆稳定性的设备,包括至少一个处理元件和至少一个存储元件,其中该至少一个存储元件用于存储程序和数据,该至少一个处理元件用于执行本申请第一方面中提供的方法。
第四方面,本申请实施例还提供了一种计算机程序,当所述计算机程序在计算机上运行时,使得所述计算机执行上述第一方面提供的方法。
第五方面,本申请实施例还提供了一种计算机存储介质,所述计算机存储介质中存储有计算机程序,当所述计算机程序被计算机执行时,使得所述计算机执行上述第一方面提供的方法。
第六方面,本申请实施例还提供了一种芯片,所述芯片用于读取存储器中存储的计算机程序,执行上述第一方面提供的方法。
第七方面,本申请实施例还提供了一种芯片系统,该芯片系统包括处理器,用于支持计算机装置实现上述第一方面提供的方法。在一种可能的设计中,所述芯片系统还包括存储器,所述存储器用于保存该计算机装置必要的程序和数据。该芯片系统可以由芯片构成,也可以包含芯片和其他分立器件。
附图说明
图1为本申请实施例提供的一种车辆转向特性的示意图;
图2为本申请实施例提供的不同驱动架构对比示意图;
图3为本申请实施例提供的两自由度车辆模型示意图;
图4为本申请实施例提供的两自由度车辆模型的横摆力矩与侧向力的对应关系示意图;
图5为本申请实施例提供的侧向附着系数的函数曲线示意图;
图6为本申请实施例提供的一种前后轴分布式驱动车辆的系统架构图;
图7为本申请实施例提供的一种控制车辆稳定性的方法的流程图;
图8为本申请实施例提供的一种控制车辆稳定性的设备的结构示意图;
图9为本申请实施例提供的又一种控制车辆稳定性的设备的结构示意图;
图10为本申请实施例提供的又一种控制车辆稳定性的设备的结构示意图。
具体实施方式
本申请提供一种控制车辆稳定性的方法及设备,用以通过控制车轮滑移率来为前后轴分布式驱动电动车辆提供额外维持车辆稳定的横摆力矩,以控制前后轴分布式驱动车辆的横向稳定性。其中,方法和设备是基于同一技术构思的,由于方法及设备解决问题的原理相似,因此设备与方法的实施可以相互参见,重复之处不再赘述。
以下,对本申请中的部分用语进行解释说明,以便于本领域技术人员理解。
1)、车辆的工况,即车辆的工作状况,又可以称为车辆的转向特性,主要分为三种:中性转向、不足转向、过多转向。
其中,中性转向指在等半径下转向,当车速变化时转向角不要求改变。不足转向指在等半径下转向,转向角随车速的提高而逐渐增加,因此行驶速度比较大的车辆在转弯时由于转向角较大而行车轨迹外偏,如图1中的左图虚线所示。过多转向指在等半径下转向,转向角随车速的提高而逐渐减小,因此行驶速度比较大的车辆在转弯时由于转向角较小而行车轨迹内偏,如图1中的右图虚线所示。
2)、车辆的状态,分为失稳和稳定两种。通常车辆的状态可以通过车辆的实际横摆角速度和用于表征驾驶员的期望轨迹的目标横摆角速度之间的角速度误差来判断。
当所述角速度误差大于第一阈值或者小于第二阈值时,所述车辆的状态为失稳。当所述角速度误差在所述第二阈值和所述第一阈值之间时,所述车辆的状态为稳定。具体如以下公式所示:
Figure PCTCN2020080531-appb-000007
其中,e γ为所述角速度误差,thd1为第一阈值,且thd1为正数,thd2为所述第二阈值,且thd2负数。
当然,目前还有很多其他方法也可以确定车辆的运行状态,例如,通过纵向车速、横向车速、车辆的质心侧偏角、纵向加速度、侧向加速度等参数来确定,具体过程本申请对此不再赘述。
3)、实际横摆角速度和目标横摆角速度之间的角速度误差,用于判断车辆的实际状态是否符合驾驶员的期望状态,即判断车辆的状态是否失稳。在本申请中,所述角速度误差可以采用以下公式确定:
Figure PCTCN2020080531-appb-000008
其中,e γ为所述角速度误差,γ为实际横摆角速度,γ d为目标横摆角速度。
4)、前后轴分布式驱动车辆,是相对于传统的集中式驱动车辆架构提出的。如图2所示,与集中式驱动车辆的中央差速器机械结构不同,前后轴分布式驱动车辆在前轴和后轴各有一套驱动系统,两个系统之间通过控制进行耦合,而不需要专门的机械结构进行硬件 连接。相对于集中式驱动车辆,前后轴分布式驱动车辆可以在前驱、后驱和四驱之间自由切换,且采用四驱模式时,由于可以独立、准确且快速地控制电机的驱动/制动转矩,使前后轴的扭矩分配比例更自由,因此,这种驱动架构为车辆的经济性、动力性、操纵性和稳定性等提供了更大的控制自由度。目前,很多车辆制造商采用这种驱动架构制造车辆。
5)、两自由度车辆模型,为假设车辆的纵向车速为匀速的情况下,对车辆的整车模型的简化。其中,涉及的两个自由度为车辆的侧向(即横向)运动和车辆的横摆运动。简化过程和坐标系定义如图3所示,其中图中的黑点表示车辆的质心,方块表示车轮。
其中,δ为车辆的车轮转向角,v x为纵向车速,v y为侧向车速,γ为车辆的横摆角速度。
根据两自由度车辆模型的运动与受力分析,在车辆稳定时纵向车速v x和横摆角速度γ均为定值,侧向运动和横摆运动对应的动力学方程的方程组为:
Figure PCTCN2020080531-appb-000009
Figure PCTCN2020080531-appb-000010
其中,v x(m/s)为车辆的纵向车速,v y(m/s)为车辆的侧向车速,且纵向车速v x为定值而侧向车速v y为变量;k f(N/rad),k r(N/rad)分别为前车轮、后车轮的等效侧偏刚度,由轮胎的自身特性决定;l f(m),l r(m)分别为质心到前轴、后轴的距离,m(kg)为车辆的整车质量。注意,以上参数中的括号内为相应参数的单位。
通过以上公式,通过以下推导,可以得到目标横摆角速度公式:
由公式(2)可得以下公式(3):
Figure PCTCN2020080531-appb-000011
将上述(3)代入公式(1),可以得到以下公式(4)
Figure PCTCN2020080531-appb-000012
对公式(4)进行简化处理,可以得到公式(5):
Figure PCTCN2020080531-appb-000013
其中,在车辆固定的情况下,m、l f、l r、k r和k f均为固定不变的参数,与车速、车辆转向角等变量不相关,因此,可以定义公式(5)中
Figure PCTCN2020080531-appb-000014
为转向特性因数K。需要说明的是,车辆固定的情况下,与K相关的参数均为固定不变的参数,即车辆固定,它的K也是固定的常量,因此,能够实现控制车辆稳定性的方法的车载处理器可以存储K的值,便于后续在计算目标横摆角速度时可以直接使用,提高计算效率。
这样,通过K的定义可以将公式(5)简化为公式(6):
Figure PCTCN2020080531-appb-000015
通过以上算法,可以通过两自由度车辆模型,得到计算目标横摆角速度的公式(6)。
6)、横摆力矩与车辆转向角、前轴(的轮胎)侧向力、后轴(的轮胎)侧向力的对应关系,可以通过上述两自由度车辆模型确定。
如图4所示,前轴侧向力相对于质心产生的正向横摆力矩为cosδF yfl f,后轴侧向力相对于质心产生的负向横摆力矩-F yrl r,因此,车辆的横摆力矩为上述正向横摆力矩和负向横摆力矩的和,如公式(7)所示:
M=cosδF yfl f-F yrl r   (7)
7)、侧向力与滑移率、侧偏角、垂向力的对应关系,具体包括前轴侧向力与前轴滑移率、前轴侧偏角、前轴垂向力的对应关系,以及后轴侧向力与后轴滑移率、后轴侧偏角、后轴垂向力的对应关系。
在本申请中,该对应关系可以通过对侧向力与横摆角速度关系的线性化(即局部线性化轮胎模型)确定,具体包括以下步骤:
a、车轮侧向力F y(N)通常由车轮滑移率λ(-)、车轮侧偏角α(deg)和车轮垂向力F z(N)决定。注意,以上参数中的括号内为相应参数的单位。
首先假设车轮侧向力与车轮垂向力呈线性比例关系,如公式(8)所示:
F y=μ yF z=μ y(λ,α)F z   (8)
其中,μ y(-)为侧向附着系数,它是车轮滑移率λ和车轮侧偏角α的非线性函数,其非线性函数关系如图5所示。
b、由于通常车轮滑移率λ在制动防抱死(Antilock Brake System,ABS)/牵引力控制系统(Traction Control System,TCS)的作用下不会大于0.3,在此滑移率区间内侧向附着系数μ y随滑移率λ的增加近似线性下降,且侧向附着系数μ y与车轮侧偏角α的关系可以近似为正比例关系。因此,在滑移率小于0.3的情况下,可以将车轮侧向力线性化为公式(9):
F y=(C 1λ+C 0)αF z,λ∈[0 0.3]  (9)
其中,C 1和C 0为线性化系数。
c、实际中车轮滑移率分为两种工况:驱动工况和制动工况,则定义车轮滑移率为公式(10):
Figure PCTCN2020080531-appb-000016
其中,R w为车轮半径(假设四个车轮半径一致);λ i特指各个车轮的滑移率,且i=1,2,3,4时分别代表左前车轮、右前车轮、左后车轮、右后车轮;在车轮在驱动工况下,λ i为正数,且介于[0 1]之间;当车轮在制动工况下,λ i为负数,且介于[-1 0]之间。
由于步骤b中的车轮侧向力默认为λ i≥0的场景,且假设制动工况和驱动工况对应的轮胎模型是对称的,所以轮胎线性化模型最终可以表示为公式(11):
F y=(C 1|λ|+C 0)αF z,λ∈[-0.3 0.3]  (11)
根据上述公式(11),可以得到前轴侧向力与前轴滑移率、前轴侧偏角、前轴垂向力的对应关系,如公式(12)所示:
F yf=(C 1ffd|+C 0ffF zf  (12)
其中,C 1f和C 0f为前轴等效轮胎模型线性化系数,λ fd为等效前轴滑移率,α f为前轴侧偏角,
Figure PCTCN2020080531-appb-000017
α 1为左前车轮侧偏角,α 2为右前车轮侧偏角,F zf为前轴垂向力,F zf=F z1+F z2,F z1为左前车轮垂向力,F z2为右前车轮垂向力。
同理,根据上述公式(11),还可以得到后轴侧向力与后轴滑移率、后轴侧偏角、后轴垂向力的对应关系,如公式(13)所示。
F yr=(C 1rfd|+C 0rrF zr   (13)
其中,C 1r和C 0r为后轴等效轮胎模型线性化系数,λ rd为等效后轴滑移率,α r为后轴侧偏角,
Figure PCTCN2020080531-appb-000018
α 3为左后车轮侧偏角,α 4为右后车轮侧偏角,F zr为后轴垂向力,F zr=F z3+F z4,F z3为左后车轮垂向力,F z4为右后车轮垂向力。
需要说明的是,本申请中所涉及的“和/或”,用于描述关联对象的关联关系,表示可以存在三种关系,例如,A和/或B,可以表示:单独存在A,同时存在A和B,单独存在B这三种情况。字符“/”一般表示前后关联对象是一种“或”的关系。本申请中所涉及的多个,是指两个或两个以上。
另外,需要理解的是,在本申请的描述中,“第一”、“第二”等词汇,仅用于区分描述的目的,而不能理解为指示或暗示相对重要性,也不能理解为指示或暗示顺序。
下面结合附图对本申请实施例做进行具体说明。
本申请实施例提供的控制车辆稳定性的方法可以应用于前后轴分布式驱动车辆中,具 体的,该控制车辆稳定性的方法可以承载在一个单独的车载电子设备(还可以称为控制车辆稳定性的设备)中,或者耦合到ESP等传统的车辆稳定性控制系统、车辆制动系统中,本申请对此不作限定。
参阅图6所示的前后轴分布式驱动车辆的系统架构图,该车辆可以包含:车载传感器、驾驶员输入装置、高级驾驶辅助系统(advanced driver assistance system,ADAS)、整车控制器、扭矩执行单元等等。
其中,所述车辆传感器用于实时采集车辆的纵向加速度a x(m/s 2)、侧向加速度a y(m/s 2)、横摆角速度γ(rad/s)、轮速ω i(rad/s)等参数。其中i=1,2,3,4,分别代表左前车辆、右前车辆、左后车辆、右后车轮。以上参数括号内为相应参数的单位。
ADAS,应用于自动驾驶场景,其中包含轨迹跟踪控制器,能够根据当前车辆的行驶情况,自动检测车辆的转向需求(即车轮转向角δ)和制动或驱动需求(即加减速需求)。
驾驶员输入装置,应用于人工驾驶场景,具体可以包含方向盘、油门踏板和制动踏板、手动档位摇杆、自动档位控制器等,用于接收驾驶员的驾驶意图,生成相应的数据。例如,在驾驶员对方向盘进行操作后,方向盘会得到方向盘转角δ SW(rad)。
整车控制器具有动力学控制功能,可以控制车辆行驶和稳定性等。进一步的,整车控制器可以包含动力学控制功能单元,用于执行本申请实施例所提供的控制车辆稳定性的方法。
所述整车控制器可以从车载传感器、驾驶员输入装置,以及ADAS中获取各种数据,并通过所述动力学控制功能单元对获取的数据进行处理,从而进行车辆的操纵性和稳定性控制。例如,所述动力学控制功能单元对获取的数据进行处理,判断车辆的状态是否稳定,以及在车辆失稳时完成车辆控制量的计算,并将控制量转化为前后和后轴(即车轮)的驱动/制动扭矩需求(即前轴扭矩和后轴扭矩)。
扭矩执行单元可以用于接收来自整车控制器的前后和后轴的驱动/制动扭矩需求,然后根据上述扭矩需求,对前轴电机和后轴电机进行控制,从而对前轴和后轴施加制动或驱动扭矩,进而实现车辆的操纵性和稳定性控制。可选的,所述扭矩执行单元中可以包含用于控制电机的电机控制单元。
可选的,所述电机控制单元的数量可以为1个也可以为2个。当所述电机控制单元的数量为1个时,所述电机控制单元可以实现对前轴电机和后轴电机的控制。当所述电机控制单元的数量为2个时,不同的电机控制单元可以分别对不同的电机进行控制。
需要说明的是,图6所示的系统架构并不构成对本申请实施例适用的前后轴分布式驱动车辆的限定,前后轴分布式驱动车辆可以包含更多或更少的部件。例如,当前后轴分布式驱动车辆不具有自动驾驶功能时,其内部不包含ADAS。又例如,当前后轴分布式驱动车辆只具有自动驾驶功能,而不具有人工驾驶功能时,其内部则不包含驾驶员输入装置。再例如,当前后轴分布式驱动车辆既具有自动驾驶功能,又具有人工驾驶功能时,其内部包含ADAS和驾驶员输入装置。
另外,还需要说明的是,在本申请实施例中,能够实时改变的参数可以记为以时间t为变量的函数,t可以表示当前时刻。当然,基于以t为变量的函数计算或估计得到的参数,也记为以t为变量的函数。
例如,在图6所示的系统架构中,车载传感器测量得到的纵向加速度、侧向加速度、横摆角速度、轮速以及方向盘输出的方向盘转角,可以分别记为a x(t)、a y(t)、γ(t)、ω i(t)、δ SW(t)。
通过方向盘转角计算得到的或者ADAS输出的车轮转向角,记为δ(t)。并且δ(t)=δ SW(t)/I s,其中I s为车辆转向比,为固定值。
通过以上参数的中的部分或全部估计得到的纵向车速v x(m/s)、车轮垂向力F zi(N)、车轮侧偏角α i(deg),车轮实际滑移率λ i(-)等,均可以记为v x(t)、F zi(t)、α i(t)、λ i(t)。
由于以上参数的计算方法均为现有且较为复杂,在本申请实施例中不再详细展开。
本申请实施例提供了一种控制车辆稳定性的方法,该方法适用于图6所示的前后轴分布式驱动车辆。所述方法由控制车辆稳定性的设备执行。所述控制车辆稳定性的设备可以为整车控制器,也可以为独立于整车控制器的一个独立电子设备,还可以是耦合有车辆稳定性控制功能的各种车载设备,在以下实施例中,所述控制车辆稳定性的设备可以简称为电子设备。另外,在本申请实施例中,所述车辆可以采用前驱、后驱、动力最优四驱、效果最优四驱中任一种驱动方式,本申请对此不作限定。
参阅图7所示,该方法具体包括以下步骤:
S701:电子设备在车辆的状态为失稳时,获取当前时刻所述车辆的需求横摆力矩、前轴实际滑移率、后轴实际滑移率,以及前轴初始扭矩和后轴初始扭矩。
本申请实施例中,车辆在行驶过程中,所述电子设备还可以采用多种方法判定车辆的状态,可以但不限于采用以下方法:
方法一:所述电子设备可以获取所述车辆的行驶参数,例如纵向车速、横向车速、车辆的质心侧偏角、纵向加速度、侧向加速度等,并通过对以上参数进行分析,确定所述车辆的状态。
方法二:由于车辆的实际横摆角速度能够表征在不改变车辆的工况情况下车辆实际的行驶轨迹,而车辆的目标横摆角速度能够表征驾驶员的期望轨迹。我们了解,一般情况下,若车辆的实际行驶轨迹严重偏离驾驶员的期望轨迹时,车辆的状态为失稳;否则,车辆的状态为稳定。因此,在本申请实施例中,可以通过车辆的实际横摆角速度和目标横摆角速度之间的角速度误差来确定车辆的状态。具体可以包含以下步骤:
A1、所述电子设备获取所述当前时刻所述车辆的纵向车速、车轮转向角和实际横摆角速度。
在步骤A1中,所述电子设备可以通过车载传感器,采集车辆当前时刻的纵向加速度a x(t)、侧向加速度a y(t)、轮速ω i(t),以及实际横摆角速度γ(t)。当所述车辆为人工驾驶时,所述电子设备还可以从当前方向盘中获取方向盘转角δ SW(t),然后通过δ SW(t)/I s,得到车轮转向角δ(t),其中,其中I s为车辆转向比,为固定值;当所述车辆为自动驾驶时,所述电子设备可以从ADAS获取车轮转向角δ(t)。
所述电子设备可以采用传统的纵向车速估计方法,根据纵向加速度a x(t)、侧向加速度a y(t)、轮速ω i(t),以及实际横摆角速度γ(t),计算当前时刻所述车辆的纵向车速v x(t)。
A2、所述电子设备根据所述纵向车速、所述车轮转向角以及存储的转向特性因数,确定目标横摆角速度。
所述目标横摆角速度符合以下公式:
Figure PCTCN2020080531-appb-000019
其中,γ d(t)为所述目标横摆角速度,l f为所述车辆的质心到前轴的距离,lr为所述车辆的质心到后轴的距离,K为所述转向特性因数,t为当前时刻。K是通过对所述车辆构建两自由度车辆模型得到的,根据以上对两自由度车辆模型的介绍可知,
Figure PCTCN2020080531-appb-000020
m为所述车辆的整车质量,k f,k r分别为前车轮、后车轮的等效侧偏刚度,由所述车辆的轮胎的自身特性决定。
在具体实施中,为了安全起见,所述电子设备还可以将所述目标横摆角速度进行饱和处理。
A3、所述电子设备计算所述实际横摆角速度与所述目标横摆角速度之间的角速度误差。可选的,所述角速度误差e γ(t)符合以下公式:
Figure PCTCN2020080531-appb-000021
由于所述车辆在行驶过程中,车载传感器会受到外界干扰,采集到的数据会存在误差,同时通过两自由度车辆模型计算得到的所述目标横摆角速度也会存在误差,虽然每个误差较小可以忽略,但是当误差累积时,会影响到所述电子设备最终的判断结果,因此,需要设定一定的阈值,来判断所述车辆的状态。
A4、所述电子设备确定所述角速度误差未落入由第一阈值和第二阈值构成的阈值区间内时,确定所述车辆的状态为失稳,其中,所述第一阈值为正数,所述第二阈值为负数。
在步骤A4中,所述电子设备可以通过如以下公式所示的判断方法,确定所述车辆的状态:
Figure PCTCN2020080531-appb-000022
其中,thd1为第一阈值,且thd1为正数,thd2为所述第二阈值,且thd2负数。
需要说明的是,本申请并不对thd1、thd2的取值进行限定,thd1、thd2的取值可以根据实际的场景以及车辆具体设定。
在一个具体的实现方式中,所述电子设备在执行上述步骤S701时,可以通过以下步骤获取所述车辆当前时刻的前轴实际滑移率λ f(t)和后轴实际滑移率λ f(t):
首先所述电子设备获取车辆当前时刻的纵向加速度a x(t)、侧向加速度a y(t)、轮速ω i(t),以及实际横摆角速度γ(t),车轮转向角δ(t),具体过程可以参见上述步骤A1。
然后所述电子设备根据以上参数,先计算纵向车速v x(t),然后根据纵向车速v x(t)和轮速ω i(t),按照传统的车轮滑移率计算方法(如以上公式(10)所示),计算四个车轮的实际滑移率λ i(t),且i=1,2,3,4时分别代表左前车轮、右前车轮、左后车轮、右后车轮。
最后,所述电子设备计算前轴实际滑移率λ f(t)=λ 1(t)+λ 2(t),以及计算后轴实际滑移率λ r(t)=λ 3(t)+λ 4(t)。
在一个具体的实现方式中,在人工驾驶场景下,所述电子设备可以根据驾驶员输入装置中油门踏板和制动踏板的开度,以及手动档位摇杆和/或自动档位控制器输出的档位,按照动力最优或者能量最优方法,计算得到前轴初始扭矩T f0和后轴初始扭矩T r0
在一个具体的实现方式中,在自动驾驶场景下,所述电子设备可以根据ADAS输出的制动或驱动需求,计算得到前轴初始扭矩T f0和后轴初始扭矩T r0
在一个具体的实现方式中,所述电子设备在执行上述步骤S701时可以通过以下步骤获取所述车辆的需求横摆力矩M(t):
所述电子设备获取所述实际横摆角速度与所述目标横摆角速度之间的角速度误差。可选的,在所述电子设备通过上述步骤A1-A4确定所述车辆的状态的情况下,所述电子设备可以直接沿用步骤A3中计算得到的所述角速度误差。
然后,所述电子设备根据获取的角速度误差,确定所述需求横摆力矩。
在一个示例中,当所述角速度误差大于所述第一阈值时,所述需求横摆力矩符合以下公式:
Figure PCTCN2020080531-appb-000023
在另一个示例中,当所述角速度误差小于所述第二阈值时,所述需求横摆力矩符合以下公式:
Figure PCTCN2020080531-appb-000024
其中,M(t)为所述需求横摆力矩,sign(δ(t))为符号函数,δ(t)为所述车轮转向角,e γ(t)为所述实际横摆角速度与所述目标横摆角速度的差值,K Po为所述车辆在过多转向工况时的比例模块增益系数,K Io为所述车辆在过多转向工况时的积分模块增益系数、K Do所述车 辆在过多转向工况时的微分模块增益系数,t 0为所述车辆的状态为失稳的时刻,t为当前时刻,K Pu为所述车辆在不足转向工况时的比例模块增益系数,K Iu所述车辆在不足转向工况时的积分模块增益系数、K Du所述车辆在不足转向工况时的微分模块增益系数。
S702:所述电子设备确定横摆力矩与前轴滑移率、后轴滑移率的对应关系。
在一个实现方式中,所述横摆力矩与前轴滑移率、后轴滑移率的对应关系为所述电子设备内部存储的。
在另一个实现方式中,所述横摆力矩与前轴滑移率、后轴滑移率的对应关系为所述电子设备根据所述车辆当前的行驶情况确定的。
通过以上第6)点对两自由度车辆模型的分析可以确定,横摆力矩与车辆转向角、前轴(的轮胎)侧向力、后轴(的轮胎)侧向力之间存在对应关系,如以上公式(7)所示。
另外,通过第7)点对侧向力与横摆角速度关系的线性化分析,还可以确定前轴侧向力与前轴滑移率、前轴侧偏角、前轴垂向力的对应关系,以及后轴侧向力与后轴滑移率、后轴侧偏角、后轴垂向力的对应关系,分别为公式(12)和公式(13)所示。
在本申请中,所述电子设备在执行S702时,可以将公式(12)和公式(13)代入公式(7),从而得到目标对应关系,即横摆力矩与前轴滑移率、后轴滑移率,以及车辆转向角、前轴侧偏角、后轴侧偏角、前轴垂向力以及后轴垂向力的对应关系,如以下公式所示:
M=cosδ(C 1ffd|+C 0ffF zfl f-(C 1rrd|+C 0rrF zrl r  公式(14)
其中,M为横摆力矩,δ为车轮转向角,C 1f和C 0f为前轴等效轮胎模型线性化系数,C 1r和C 0r为后轴等效轮胎线性化系数,λ fd为前轴等效滑移率,λ rd为后轴等效滑移率,α f为前轴侧偏角,α r为后轴侧偏角,F zf为前轴垂向力,F zr为后轴垂向力,l f为车辆的质心到前轴的距离,l r为车辆的质心到后轴的距离。
另外,在当前时刻,上述公式(14)中,除M、λ fd、λ rd以外的其他参数的取值,所述电子设备均可以确定。例如,δ为所述电子设备获取的当前时刻的车轮转向角δ(t),α f为所述电子设备当前时刻计算的前轴侧偏角
Figure PCTCN2020080531-appb-000025
α r为所述电子设备当前时刻计算的后轴侧偏角
Figure PCTCN2020080531-appb-000026
F zf为所述电子设备当前时刻计算的前轴垂向力F zf(t)=F z1(t)+F z2(t),F zr为所述电子设备当前时刻计算的后轴垂向力F zr(t)=F z3(t)+F z4(t),其中,α i(t)为当前时刻各个车轮的侧偏角,F zi(t)为当前时刻各个车轮的垂向力,且i=1,2,3,4时分别代表左前车轮、右前车轮、左后车轮、右后车轮。
需要说明的是,α i(t)为所述电子设备按照现有计算方法根据质心侧偏角确定,而所述质心侧偏角可以为所述电子设备根据所述车辆当前时刻的纵向加速度a x(t)、侧向加速度a y(t)、轮速ω i(t),以及实际横摆角速度γ(t),车轮转向角δ(t)等参数,估计得到的。F zi(t)也为所述电子设备按照现有的计算方法,根据上述参数、车辆的制动或驱动需求,以及所述车辆的质量、l f、l r等估计得到的。
综上,所述电子设备可以获取公式(14)中除M、λ fd、λ rd以外的其他参数的取值并代入公式(14),所述电子设备可以建立横摆力矩与前轴滑移率、后轴滑移率的对应关系。
S703:所述电子设备根据确定的所述横摆力矩与前轴滑移率、后轴滑移率的对应关系,以及所述需求横摆力矩,确定前轴目标滑移率和后轴目标滑移率。
在一个具体的实现方式中,所述电子设备可以通过以下步骤,确定前轴目标滑移率和后轴目标滑移率:
B1、所述电子设备根据所述横摆力矩与前轴滑移率、后轴滑移率的对应关系,以及所述需求横摆力矩,确定多个滑移率组合,其中,每个滑移率组合包含一个前轴滑移率和一个后轴滑移率。
在步骤B1中,所述电子设备可以将S701获取的所述需求横摆力矩M(t)代入公式(14),可以得到前轴滑移率和后轴滑移率的一个约束方程。由于所述约束方程中前后滑移率和后轴滑移率均为绝对值,因此,解上述约束方程,可以得到多个滑移率组合。
B2、所述电子设备在所述多个滑移率组合中,选择前轴滑移率和后轴滑移率小于0的至少一个滑移率组合。
在本申请实施例中,虽然当前所述车辆可以处于驱动模式,也可以是处于制动模式,但是由于当前时刻所述车辆失稳,为了保证行驶安全,一般需要对所述车辆进行制动来快速地保证车辆的稳定。换句话说,由于所述车辆当前处于制动模式,所以所述车辆的前轴滑移率和后轴滑移率均小于0。
B3、所述电子设备在所述至少一个滑移率组合中选择前轴滑移率的绝对值和后轴滑移率的绝对值之和最小的目标滑移率组合。
我们知道,在车辆控制领域,车辆的滑移率的绝对值越小,制动效果越好,车辆的形式就越安全。因此,为了保证所述车辆的行驶安全,所述电子设备可以在所述至少一个滑移率组合中选择前轴滑移率的绝对值和后轴滑移率的绝对值之和最小的目标滑移率组合。
B4、所述电子设备确定所述目标滑移率组合中的前轴滑移率为所述前轴目标滑移率,并确定所述目标滑移率组合中的后轴滑移率为所述后轴目标滑移率。
通过上述步骤,所述电子设备可以在保证所述车辆的行驶安全的前提下,快速且准确地得到符合当前行驶情况的前轴目标滑移率λ fd(t)和后轴目标滑移率λ rd(t)。
S704:所述电子设备根据所述前轴目标滑移率和所述前轴实际滑移率的差值,以及所述前轴初始扭矩,确定前轴目标扭矩;并根据所述后轴目标滑移率和所述后轴实际滑移率的差值,以及所述后轴初始扭矩,确定后轴目标扭矩。
在一个具体的实现方式中,所述前轴目标扭矩符合以下公式:
Figure PCTCN2020080531-appb-000027
所述后轴目标扭矩符合以下公式:
Figure PCTCN2020080531-appb-000028
其中,T f(t)为所述前轴目标扭矩,T f0为所述前轴初始扭矩,e λf(t)为所述前轴目标滑移率和所述前轴实际滑移率的差值,即e λf(t)=λ fd(t)-λ f(t),T r(t)为所述后轴目标扭矩,T r0为所述后轴初始扭矩,e λr(t)为所述后轴目标滑移率和所述后轴实际滑移率的差值,即e λr(t)=λ rd(t)-λ f(t),K P为比例模块增益系数,K I为积分模块增益系数,K D为微分模块增益系数,t 0为所述车辆的状态为失稳的时刻,t为当前时刻。
S705:所述电子设备根据所述前轴目标扭矩和所述后轴目标扭矩,对所述车辆进行稳定性控制。
在一个具体的实现方式中,所述电子设备可以将所述前轴目标扭矩T f(t)和所述后轴目标扭矩T r(t)发送给所述车辆中的扭矩执行单元,这样,所述扭矩执行单元可以根据所述前轴目标扭矩T f(t),对前轴电机进行控制,以及根据所述后轴目标扭矩T r(t),对后轴电机进行控制,以使前轴电机和后轴电机对前轴和后轴分别施加相应的目标扭矩,从而实现所述车辆的稳定性控制,进而保证所述车辆行驶的稳定性和安全性。
在上述实现方式中,由于所述车辆最终由前轴电机和后轴电机作为最终稳定性控制的执行主体,其控制响应更加快速,因此所述车辆的横摆角速度的收敛速度更快,进而可以使所述车辆从失稳状态进入稳定状态的时间更短,从而可以进一步保证所述车辆的安全。
在另一个实现方式中,所述电子设备在所述车辆处于失稳状态时,持续执行以上步骤,实时通过监控车辆的前轴滑移率和后轴滑移率,确定前轴目标扭矩和后轴目标扭矩,从而持续对所述车辆进行稳定性控制。
本申请实施例提供了一种控制车辆稳定性的方法,在该方法中,电子设备在确定车辆失稳时,可以获取前轴实际滑移率和后轴实际滑移率,然后快速且准确地得到符合当前行驶情况的前轴目标滑移率和后轴目标滑移率,进而可以根据所述前轴目标滑移率和所述前轴实际滑移率的差值,以及所述后轴目标滑移率和所述后轴实际滑移率的差值,确定能够保证所述车辆稳定的前轴目标扭矩和后轴目标扭矩,进而可以对车辆进行稳定性控制。
首先,该方法考虑到车辆的横摆运动,并且通过前后轴滑移率补偿的方式来为车辆提供额外维持车辆横向稳定性的横摆力矩,从而控制车辆的横向稳定性,进而提升车辆行驶过程中的稳定性。另外,由于所述前轴目标滑移率和后轴目标滑移率是根据当前时刻车辆的需求横摆力矩得到的,因此实时计算的前轴目标滑移率和后轴目标滑移率更符合当前时刻所述车辆的行驶情况,即无论所述车辆在稳定性控制使能是何种驱动方式,通过该方法均可以快速且准确地保证车辆的稳定性。
再者,该方法通过两自由度车辆模型和局部线性化轮胎模型,建立横摆力矩与前轴滑移率、后轴滑移率的对应关系,从而所述电子设备可以实时、准确地得到更符合当前时刻所述车辆的行驶情况的前轴目标滑移率和后轴目标滑移率,从而可以实时的对车辆进行控制。
另外,该方法可以在不增加前后轴分布式驱动车辆的硬件成本的情况下,仅通过应用软件控制,即可提高所述车辆在各种驱动方式下的稳定性。并且该方法最后的稳定性控制由电机执行,由于电机的响应速度极快,相对于传统的液压制动方式,该方法可以使车辆稳定性控制的过程更加平顺,提高了驾驶员的使用体验。
还需要说明的是,本申请实施例提供的控制车辆稳定性的方法可以与传统的ESP互为冗余和备份,即车辆可以同时通过两套稳定性控制机制实现自身的稳定性控制,进一步提高了车辆的稳定性。
基于以上实施例,本申请实施例还提供了一种控制车辆稳定性的设备,该设备适用于图6所示的前后轴分布式驱动车辆,用于实现上述控制车辆稳定性的方法。所述设备可以为整车控制器,也可以为独立于整车控制器的一个独立电子设备,还可以是耦合有车辆稳定性控制功能的各种车载设备。如图8所示,按照逻辑功能划分,所述设备包含以下10个模块:信号处理(参数估计),目标横摆角速度计算,车辆的状态确定,需求横摆力矩计算,前轴垂向力、后轴垂向力计算,前轴侧偏角、后轴侧偏角计算,前轴目标滑移率、后轴目标滑移率计算,前轴实际滑移率、后轴实际滑移率计算,前轴初始扭矩、后轴初始扭矩计算,前轴目标扭矩、后轴目标扭矩计算。
所述设备与车载传感器、驾驶员输入装置、ADAS,以及扭矩执行单元之间通过总线相连。其中,所述设备可以从所述车载传输器获取当前时刻车辆的纵向加速度、侧向加速度、轮速,以及实际横摆角速度。在车辆处于人工驾驶场景中,所述设备可以从所述驾驶员输入装置获取方向盘转角、油门踏板开度、制动踏板开度,以及档位。在自动驾驶场景中,所述设备可以从所述ADAS获取车轮转向角以及制动或驱动需求。
所述设备在执行控制车辆稳定性的方法,得到前轴目标扭矩和后轴目标扭矩后,可以发送给扭矩执行单元,以使所述扭矩执行单元对前轴电机和后轴电机进行控制,从而对前轴和后轴施加制动或驱动扭矩,最终实现车辆的操纵性和稳定性控制。
下面对所述设备在实现上述控制车辆稳定性的方法的过程中,各个模块的功能进行介绍。
所述数据处理模块,用于接收车载传感器、驾驶员输入装置、ADAS发送的原始数据,并基于接收的原始数据,计算或估计其他相关参数,如图8所示。
例如,所述数据处理模块可以采用传统的纵向车速估计方法,根据纵向加速度、侧向加速度、轮速,以及实际横摆角速度,计算当前时刻车辆的纵向车速。
又例如,所述数据处理模块根据方向盘转角计算车轮转向角。
再例如,所述数据处理模块根据纵向加速度、侧向加速度、轮速,以及实际横摆角速度,车轮转向角等计算车轮的质心侧偏角,以及基于所述质心侧偏角估计每个车轮的侧偏角。
再例如,所述数据处理模块根据纵向加速度、侧向加速度、轮速,实际横摆角速度,车轮转向角,车辆的制动或驱动需求,以及所述车辆的质量、l f、l r等,估计每个车轮的 垂向力。
再例如,所述数据处理模块根据纵向车速和轮速,计算每个车轮的实际滑移率。
所述目标横摆角速度计算模块,用于根据车轮转向角进而纵向车速,计算目标横摆角速度。其中,所述目标横摆角速度符合以下公式:
Figure PCTCN2020080531-appb-000029
其中,γ d(t)为所述目标横摆角速度,v x(t)为所述纵向车速,δ(t)为所述车轮转向角,l f为所述车辆的质心到前轴的距离,l r为所述车辆的质心到后轴的距离,K为所述转向特性因数,t为当前时刻。
所述车辆的状态确定模块,用于判定车辆的状态。可选的,所述车辆的状态确定模块可以采用多种方法实现。
例如,所述车辆的状态确定模块可以根据纵向车速、横向车速、质心侧偏角、纵向加速度、侧向加速度等进行分析,确定所述车辆的状态。
又例如,所述车辆的状态确定模块可以根据所述实际横摆角速度与所述目标横摆角速度之间的角速度误差,确定所述车辆的状态。其中,所述角速度误差符合以下公式:
Figure PCTCN2020080531-appb-000030
其中,e γ(t)为所述角速度误差,γ(t)为所述实际横摆角速度,γ d(t)为所述目标横摆角速度。
所述车辆的状态符合以下公式:
Figure PCTCN2020080531-appb-000031
其中,thd1为第一阈值,且thd1为正数,thd2为所述第二阈值,且thd2负数。
需要说明的是,本申请并不对thd1、thd2的取值进行限定,thd1、thd2的取值可以根据实际的场景以及车辆具体设定。
所述需求横摆力矩计算模块,用于在所述车辆的状态确定模块确定所述车辆失稳时,计算需求横摆力矩。所述需求横摆力矩根据所述角速度误差和车轮转向角,计算需求横摆力矩。
当所述角速度误差大于所述第一阈值时,所述需求横摆力矩符合以下公式:
Figure PCTCN2020080531-appb-000032
当所述角速度误差小于所述第二阈值时,所述需求横摆力矩符合以下公式:
Figure PCTCN2020080531-appb-000033
其中,M(t)为所述需求横摆力矩,sign(δ(t))为符号函数,δ(t)为所述车轮转向角,e γ(t)为所述实际横摆角速度与所述目标横摆角速度的差值,K Po为所述车辆在过多转向工况时的比例模块增益系数,K Io为所述车辆在过多转向工况时的积分模块增益系数、K Do所述车辆在过多转向工况时的微分模块增益系数,t 0为所述车辆的状态为失稳的时刻,t为当前时刻,K Pu为所述车辆在不足转向工况时的比例模块增益系数,K Iu所述车辆在不足转向工况时的积分模块增益系数、K Du所述车辆在不足转向工况时的微分模块增益系数。
所述前轴垂向力、后轴垂向力计算模块,用于根据四个车轮的垂向力,计算前轴垂向力和后轴垂向力,其中,前轴垂向力F zf(t)=F z1(t)+F z2(t),后轴垂向力F zr(t)=F z3(t)+F z4(t),F zi(t)为当前时刻各个车轮的垂向力,且i=1,2,3,4时分别代表左前车轮、右前车轮、左后车轮、右后车轮。
所述前轴侧偏角、后轴侧偏角计算模块,用于根据四个车轮的侧偏角,计算前轴侧偏角和后轴侧偏角,其中,前轴侧偏角
Figure PCTCN2020080531-appb-000034
后轴侧偏角
Figure PCTCN2020080531-appb-000035
α i(t)为当前时刻各个车轮的侧偏角。
所述前轴目标滑移率、后轴目标滑移率计算模块,用于根据需求横摆力矩,车轮转向角、前轴垂向力和后轴垂向力,以及前轴侧偏角和后轴侧偏角,以及存储的目标对应关系(如公式14所示),计算前轴目标滑移率和后轴目标滑移率。
在一个具体的实现方式中,所述前轴目标滑移率、后轴目标滑移率计算模块首先将获取的车轮转向角、前轴垂向力和后轴垂向力,以及前轴侧偏角和后轴侧偏角,代入以下公式,从而得到横摆力矩与前轴滑移率、后轴滑移率的对应关系:
M=cosδ(C 1ffd|+C 0ffF zfl f-(C 1rrd|+C 0rrF zrl r  公式(14)
其中,M为横摆力矩,δ为车轮转向角,C 1f和C 0f为前轴等效轮胎模型线性化系数,C 1r和C 0r为后轴等效轮胎线性化系数,λ fd为前轴等效滑移率,λ rd为后轴等效滑移率,α f为前轴侧偏角,α r为后轴侧偏角,F zf为前轴垂向力,F zr为后轴垂向力,l f为车辆的质心到前轴的距离,l r为车辆的质心到后轴的距离。
然后所述前轴目标滑移率、后轴目标滑移率计算模块根据所述需求横摆力矩,以及上述横摆力矩与前轴滑移率、后轴滑移率的对应关系,计算得到前轴目标滑移率和后轴目标滑移率。
所述前轴实际滑移率、后轴实际滑移率计算模块,用于根据四个车轮的实际滑移率,计算前轴实际滑移率、后轴实际滑移率。其中,前轴实际滑移率λ f(t)=λ 1(t)+λ 2(t),以及后轴实际滑移率λ r(t)=λ 3(t)+λ 4(t)。λ i(t)为当前时刻各个车轮的实际滑移率。
所述前轴初始扭矩、后轴初始扭矩计算模块,用于在人工驾驶场景下,所述电子设备可以根据驾驶员输入装置输出的油门踏板和制动踏板的开度,以及手动档位摇杆和/或自动档位控制器输出的档位,按照动力最优或者能量最优方法,计算得到前轴初始扭矩T f0和后轴初始扭矩T r0。在自动驾驶场景下,所述电子设备可以根据ADAS输出的制动或驱动需求,计算得到前轴初始扭矩T f0和后轴初始扭矩T r0
所述前轴目标扭矩、后轴目标扭矩计算模块,用于获取所述前轴目标滑移率和所述前轴实际滑移率的差值e λf(t),然后根据e λf(t)以及前轴初始扭矩,公式
Figure PCTCN2020080531-appb-000036
Figure PCTCN2020080531-appb-000037
得到前轴目标扭矩;以及获取所述后轴目标滑移率和所述后轴实际滑移率的差值e λr(t),然后根据e λr(t)以及后轴初始扭矩,公式
Figure PCTCN2020080531-appb-000038
Figure PCTCN2020080531-appb-000039
得到后轴扭矩。
其中,T f(t)为所述前轴目标扭矩,T f0为所述前轴初始扭矩,e λf(t)为所述前轴目标滑移率和所述前轴实际滑移率的差值,即e λf(t)=λ fd(t)-λ f(t),T r(t)为所述后轴目标扭矩,T r0为所述后轴初始扭矩,e λr(t)为所述后轴目标滑移率和所述后轴实际滑移率的差值,即e λr(t)=λ rd(t)-λ f(t),K P为比例模块增益系数,K I为积分模块增益系数,K D为微分模块增益系数,t 0为所述车辆的状态为失稳的时刻,t为当前时刻。
基于以上实施例,本申请实施例还提供了一种控制车辆稳定性的设备,该设备适用于图6所示的前后轴分布式驱动车辆,用于实现上述控制车辆稳定性的方法,且具有图8所示的设备的功能。参阅图9所示,该设备900包括:获取单元901、确定单元902,扭矩计算单元903,稳定性控制单元904。下面介绍所述设备900在进行车辆稳定性控制时,各个单元的功能。
获取单元901,用于在车辆的状态为失稳时,获取当前时刻所述车辆的需求横摆力矩、前轴实际滑移率、后轴实际滑移率,以及前轴初始扭矩和后轴初始扭矩;
确定单元902,用于确定所述车辆的横摆力矩与前轴滑移率、后轴滑移率的对应关系;以及根据确定的所述横摆力矩与前轴滑移率、后轴滑移率的对应关系,以及所述需求横摆 力矩,确定前轴目标滑移率和后轴目标滑移率;
扭矩计算单元903,用于根据所述前轴目标滑移率和所述前轴实际滑移率的差值,以及所述前轴初始扭矩,确定前轴目标扭矩;以及根据所述后轴目标滑移率和所述后轴实际滑移率的差值,以及所述后轴初始扭矩,确定后轴目标扭矩;
稳定性控制单元904,用于根据所述前轴目标扭矩和所述后轴目标扭矩,对所述车辆进行稳定性控制。
在一个实现方式中,所述设备还包括状态确定单元905,用于通过以下步骤,确定车辆的状态为失稳:
获取所述当前时刻所述车辆的纵向车速、车轮转向角和实际横摆角速度;
根据所述纵向车速、所述车轮转向角以及存储的转向特性因数,确定目标横摆角速度,其中,所述转向特性因数用于表征所述车辆的转向特性的常量;
计算所述实际横摆角速度与所述目标横摆角速度之间的角速度误差;
若所述角速度误差未落入预设阈值区间内,确定所述车辆的状态为失稳,其中,所述预设阈值区间为所述第一阈值和所述第二阈值构成的区间,其中,所述第一阈值为正数,所述第二阈值为负数。
示例性的,所述目标横摆角速度符合以下公式:
Figure PCTCN2020080531-appb-000040
其中,γ d(t)为所述目标横摆角速度,v x(t)为所述纵向车速,δ(t)为所述车轮转向角,l f为所述车辆的质心到前轴的距离,l r为所述车辆的质心到后轴的距离,K为所述转向特性因数,t为当前时刻。
在一个实现方式中,所述获取单元901,可以根据所述角速度误差,确定所述需求横摆力矩。
示例性的,当所述角速度误差大于所述第一阈值时,所述需求横摆力矩符合以下公式:
Figure PCTCN2020080531-appb-000041
当所述角速度误差小于所述第二阈值时,所述需求横摆力矩符合以下公式:
Figure PCTCN2020080531-appb-000042
其中,M(t)为所述需求横摆力矩,sign(δ(t))为符号函数,δ(t)为所述车轮转向角,e γ(t)为所述实际横摆角速度与所述目标横摆角速度的差值,K Po为所述车辆在过多转向工况时的比例模块增益系数,K Io为所述车辆在过多转向工况时的积分模块增益系数、K Do所述车辆在过多转向工况时的微分模块增益系数,t 0为所述车辆的状态为失稳的时刻,t为当前时刻,K Pu为所述车辆在不足转向工况时的比例模块增益系数,K Iu所述车辆在不足转向工况时的积分模块增益系数、K Du所述车辆在不足转向工况时的微分模块增益系数。
示例性的,所述角速度误差符合以下公式:
Figure PCTCN2020080531-appb-000043
其中,e γ(t)为所述角速度误差,γ(t)为所述实际横摆角速度,γ d(t)为所述目标横摆角速度。
在一个实现方式中,所述确定单元902,可以通过以下步骤确定所述横摆力矩与前轴滑移率、后轴滑移率的对应关系:
获取所述当前时刻所述车辆的车轮转向角、前轴侧偏角、后轴侧偏角、前轴垂向力以及后轴垂向力;根据所述车轮转向角、所述前轴侧偏角、所述后轴侧偏角、所述前轴垂向力以及所述后轴垂向力,建立所述横摆力矩与前轴滑移率、后轴滑移率的对应关系。
示例性的,所述横摆力矩与前轴滑移率、后轴滑移率的对应关系符合以下公式:
M=cosδ(C 1ffd|+C 0ffF zfl f-(C 1rrd|+C 0rrF zrl r
其中,M为横摆力矩,δ为车轮转向角,C 1f和C 0f为前轴等效轮胎模型线性化系数,C 1r和C 0r为后轴等效轮胎线性化系数,λ fd为前轴滑移率,λ rd为后轴滑移率,α f为前轴侧偏角,α r为后轴侧偏角,F zf为前轴垂向力,F zr为后轴垂向力,l f为车辆的质心到前轴的距离,l r为车辆的质心到后轴的距离。
在一个实现方式中,所述确定单元902,可以通过以下步骤,根据确定的所述横摆力矩与前轴滑移率、后轴滑移率的对应关系,以及所述需求横摆力矩,确定前轴目标滑移率和后轴目标滑移率:
根据所述横摆力矩与前轴滑移率、后轴滑移率的对应关系,以及所述需求横摆力矩,确定多个滑移率组合,其中,每个滑移率组合包含一个前轴滑移率和一个后轴滑移率;
在所述多个滑移率组合中,选择前轴滑移率和后轴滑移率小于0的至少一个滑移率组合;
在所述至少一个滑移率组合中选择前轴滑移率的绝对值和后轴滑移率的绝对值之和最小的目标滑移率组合;
确定所述目标滑移率组合中的前轴滑移率为所述前轴目标滑移率,并确定所述目标滑移率组合中的后轴滑移率为所述后轴目标滑移率。
示例性的,所述前轴目标扭矩符合以下公式:
Figure PCTCN2020080531-appb-000044
所述后轴目标扭矩符合以下公式:
Figure PCTCN2020080531-appb-000045
其中,T f(t)为所述前轴目标扭矩,T f0为所述前轴初始扭矩,e λf(t)为所述前轴目标滑移率和所述前轴实际滑移率的差值,T r(t)为所述后轴目标扭矩,T r0为所述后轴初始扭矩,e λr(t)为所述后轴目标滑移率和所述后轴实际滑移率的差值,K P为比例模块增益系数,K I为积分模块增益系数,K D为微分模块增益系数,t 0为所述车辆的状态为失稳的时刻,t为当前时刻。
在以上实施例中提供了一种控制车辆稳定性的设备,该设备在车辆失稳时,可以获取前轴实际滑移率和后轴实际滑移率,然后快速且准确地得到符合当前行驶情况的前轴目标滑移率和后轴目标滑移率,进而可以根据所述前轴目标滑移率和所述前轴实际滑移率的差值,以及所述后轴目标滑移率和所述后轴实际滑移率的差值,确定能够保证所述车辆稳定的前轴目标扭矩和后轴目标扭矩,进而可以对车辆进行稳定性控制。由于该设备考虑到车辆的横摆运动,并且通过前后轴滑移率补偿的方式来为车辆提供额外维持车辆横向稳定性的横摆力矩,从而控制车辆的横向稳定性,进而提升车辆行驶过程中的稳定性。另外,由于所述前轴目标滑移率和后轴目标滑移率是根据当前时刻车辆的需求横摆力矩得到的,因此实时计算的前轴目标滑移率和后轴目标滑移率更符合当前时刻所述车辆的行驶情况,即无论所述车辆在稳定性控制使能是何种驱动方式,该设备均可以快速且准确地保证车辆的稳定性。
需要说明的是,本申请实施例中对模块的划分是示意性的,仅仅为一种逻辑功能划分,实际实现时可以有另外的划分方式,另外,在本申请各个实施例中的各功能单元可以集成在一个处理单元中,也可以是单独物理存在,也可以两个或两个以上单元集成在一个单元中。上述集成的单元既可以采用硬件的形式实现,也可以采用软件功能单元的形式实现。
所述集成的单元如果以软件功能单元的形式实现并作为独立的产品销售或使用时,可以存储在一个计算机可读取存储介质中。基于这样的理解,本申请的技术方案本质上或者说对现有技术做出贡献的部分或者该技术方案的全部或部分可以以软件产品的形式体现出来,该计算机软件产品存储在一个存储介质中,包括若干指令用以使得一台计算机设备(可以是个人计算机,服务器,或者网络设备等)或处理器(processor)执行本申请各个实施例所述方法的全部或部分步骤。而前述的存储介质包括:U盘、移动硬盘、只读存储 器(Read-Only Memory,ROM)、随机存取存储器(Random Access Memory,RAM)、磁碟或者光盘等各种可以存储程序代码的介质。
基于以上实施例,本申请实施例还提供了一种控制车辆稳定性的设备,该设备适用于图6所示的前后轴分布式驱动车辆,用于实现上述控制车辆稳定性的方法,且具有图8和图9所示的设备的功能。参阅图10所示,所述设备1000中包括:通信接口1001、处理器1002,以及存储器1003。
所述通信接口1001和所述存储器1003与所述处理器1002之间相互连接。可选的,所述通信接口1001和所述存储器1003与所述处理器1002之间可以通过总线相互连接;所述总线可以是外设部件互连标准(peripheral component interconnect,PCI)总线或扩展工业标准结构(extended industry standard architecture,EISA)总线等。所述总线可以分为地址总线、数据总线、控制总线等。为便于表示,图10中仅用一条粗线表示,但并不表示仅有一根总线或一种类型的总线。
所述通信接口1001用于与所述车辆中的其他部件通信。例如,所述通信接口1001从车载传感器、驾驶员输入装置、ADAS等部件中获取各种数据。又例如,所述通信接口1001将计算的前轴目标扭矩和后轴目标扭矩发送给扭矩执行单元,用于实现最后的车辆稳定性控制。
所述处理器1002用于实现如图7所示的控制车辆稳定性的方法,具体可以参见上述实施例中的描述,此处不再赘述。可选的,所述处理器1002可以是中央处理器(central processing unit,CPU),或者其他硬件芯片。上述硬件芯片可以是专用集成电路(application-specific integrated circuit,ASIC),可编程逻辑器件(programmable logic device,PLD)或其组合。上述PLD可以是复杂可编程逻辑器件(complex programmable logic device,CPLD),现场可编程逻辑门阵列(field-programmable gate array,FPGA),通用阵列逻辑(generic array logic,GAL)或其任意组合。所述处理器1002在实现上述功能时,可以通过硬件实现,当然也可以通过硬件执行相应的软件实现。
所述存储器1003用于存放程序指令和数据等。具体地,程序指令可以包括程序代码,该程序代码包括计算机操作的指令。存储器1003可能包含随机存取存储器(random access memory,RAM),也可能还包括非易失性存储器(non-volatile memory),例如至少一个磁盘存储器。所述处理器1002执行所述存储器1003所存放的程序,并通过上述各个部件,实现上述功能,从而最终实现以上实施例提供的方法。
基于以上实施例,本申请实施例还提供了一种计算机程序,当所述计算机程序在计算机上运行时,使得所述计算机执行以上实施例提供的方法。
基于以上实施例,本申请实施例还提供了一种计算机存储介质,该计算机存储介质中存储有计算机程序,所述计算机程序被计算机执行时,使得计算机执行以上实施例提供的方法。
基于以上实施例,本申请实施例还提供了一种芯片,所述芯片用于读取存储器中存储的计算机程序,实现以上实施例提供的方法。
基于以上实施例,本申请实施例提供了一种芯片系统,该芯片系统包括处理器,用于支持计算机装置实现以上实施例提供的方法中终端设备所涉及的功能。在一种可能的设计中,所述芯片系统还包括存储器,所述存储器用于保存该计算机装置必要的程序和数据。该芯片系统,可以由芯片构成,也可以包含芯片和其他分立器件。
本领域内的技术人员应明白,本申请的实施例可提供为方法、系统、或计算机程序产品。因此,本申请可采用完全硬件实施例、完全软件实施例、或结合软件和硬件方面的实施例的形式。而且,本申请可采用在一个或多个其中包含有计算机可用程序代码的计算机可用存储介质(包括但不限于磁盘存储器、CD-ROM、光学存储器等)上实施的计算机程序产品的形式。
本申请是参照根据本申请的方法、设备(系统)、和计算机程序产品的流程图和/或方框图来描述的。应理解可由计算机程序指令实现流程图和/或方框图中的每一流程和/或方框、以及流程图和/或方框图中的流程和/或方框的结合。可提供这些计算机程序指令到通用计算机、专用计算机、嵌入式处理机或其他可编程数据处理设备的处理器以产生一个机器,使得通过计算机或其他可编程数据处理设备的处理器执行的指令产生用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的装置。
这些计算机程序指令也可存储在能引导计算机或其他可编程数据处理设备以特定方式工作的计算机可读存储器中,使得存储在该计算机可读存储器中的指令产生包括指令装置的制造品,该指令装置实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能。
这些计算机程序指令也可装载到计算机或其他可编程数据处理设备上,使得在计算机或其他可编程设备上执行一系列操作步骤以产生计算机实现的处理,从而在计算机或其他可编程设备上执行的指令提供用于实现在流程图一个流程或多个流程和/或方框图一个方框或多个方框中指定的功能的步骤。
显然,本领域的技术人员可以对本申请进行各种改动和变型而不脱离本申请的范围。这样,倘若本申请的这些修改和变型属于本申请权利要求及其等同技术的范围之内,则本申请也意图包含这些改动和变型在内。

Claims (24)

  1. 一种控制车辆稳定性的方法,其特征在于,包括:
    车辆的状态为失稳时,获取当前时刻所述车辆的需求横摆力矩、前轴实际滑移率、后轴实际滑移率,以及前轴初始扭矩和后轴初始扭矩;
    确定所述车辆的横摆力矩与前轴滑移率、后轴滑移率的对应关系;
    根据确定的所述横摆力矩与前轴滑移率、后轴滑移率的对应关系,以及所述需求横摆力矩,确定前轴目标滑移率和后轴目标滑移率;
    根据所述前轴目标滑移率和所述前轴实际滑移率的差值,以及所述前轴初始扭矩,确定前轴目标扭矩;
    根据所述后轴目标滑移率和所述后轴实际滑移率的差值,以及所述后轴初始扭矩,确定后轴目标扭矩;
    根据所述前轴目标扭矩和所述后轴目标扭矩,对所述车辆进行稳定性控制。
  2. 如权利要求1所述的方法,其特征在于,还包括:
    获取所述当前时刻所述车辆的纵向车速、车轮转向角和实际横摆角速度;
    根据所述纵向车速、所述车轮转向角以及存储的转向特性因数,确定目标横摆角速度,其中,所述转向特性因数用于表征所述车辆的转向特性的常量;
    计算所述实际横摆角速度与所述目标横摆角速度之间的角速度误差;
    若所述角速度误差未落入预设阈值区间内,确定所述车辆的状态为失稳,其中,所述预设阈值区间为所述第一阈值和所述第二阈值构成的区间,所述第一阈值为正数,所述第二阈值为负数。
  3. 如权利要求2所述的方法,其特征在于,所述目标横摆角速度符合以下公式:
    Figure PCTCN2020080531-appb-100001
    其中,γ d(t)为所述目标横摆角速度,v x(t)为所述纵向车速,δ(t)为所述车轮转向角,l f为所述车辆的质心到前轴的距离,l r为所述车辆的质心到后轴的距离,K为所述转向特性因数,t为当前时刻。
  4. 如权利要求2或3所述的方法,其特征在于,获取所述需求横摆力矩,包括:
    根据所述角速度误差,确定所述需求横摆力矩。
  5. 如权利要求4所述的方法,其特征在于,
    当所述角速度误差大于所述第一阈值时,所述需求横摆力矩符合以下公式:
    Figure PCTCN2020080531-appb-100002
    当所述角速度误差小于所述第二阈值时,所述需求横摆力矩符合以下公式:
    Figure PCTCN2020080531-appb-100003
    其中,M(t)为所述需求横摆力矩,sign(δ)t))为符号函数,δ(t)为所述车轮转向角,e γ(t)为所述实际横摆角速度与所述目标横摆角速度的差值,K Po为所述车辆在过多转向工况时的比例模块增益系数,K Io为所述车辆在过多转向工况时的积分模块增益系数、K Do所述车辆在过多转向工况时的微分模块增益系数,t 0为所述车辆的状态为失稳的时刻,t为当前时刻,K Pu为所述车辆在不足转向工况时的比例模块增益系数,K Iu所述车辆在不足转向工况时的积分模块增益系数、K Du所述车辆在不足转向工况时的微分模块增益系数。
  6. 如权利要求2-5任一项所述的方法,其特征在于,所述角速度误差符合以下公式:
    Figure PCTCN2020080531-appb-100004
    其中,e γ(t)为所述角速度误差,γ(t)为所述实际横摆角速度,γ d(t)为所述目标横摆角速度。
  7. 如权利要求1-6任一项所述的方法,其特征在于,确定所述车辆的横摆力矩与前轴滑移率、后轴滑移率的对应关系,包括:
    获取所述当前时刻所述车辆的车轮转向角、前轴侧偏角、后轴侧偏角、前轴垂向力以及后轴垂向力;
    根据所述车轮转向角、所述前轴侧偏角、所述后轴侧偏角、所述前轴垂向力以及所述后轴垂向力,建立所述横摆力矩与前轴滑移率、后轴滑移率的对应关系。
  8. 如权利要求7所述的方法,其特征在于,所述横摆力矩与前轴滑移率、后轴滑移率的对应关系符合以下公式:
    M=cosδ(C 1ffd|+C 0ffF zfl f-(C 1rrd|+C 0rrF zrl r
    其中,M为横摆力矩,δ为所述车轮转向角,C 1f和C 0f为前轴等效轮胎模型线性化系数,C 1r和C 0r为后轴等效轮胎线性化系数,λ fd为前轴滑移率,λ rd为后轴滑移率,α f为所述前轴侧偏角,α r为所述后轴侧偏角,F zf为所述前轴垂向力,F zr为所述后轴垂向力,l f为车辆的质心到前轴的距离,l r为车辆的质心到后轴的距离。
  9. 如权利要求8所述的方法,其特征在于,根据确定的所述横摆力矩与前轴滑移率、后轴滑移率的对应关系,以及所述需求横摆力矩,确定前轴目标滑移率和后轴目标滑移率,包括:
    根据所述横摆力矩与前轴滑移率、后轴滑移率的对应关系,以及所述需求横摆力矩,确定多个滑移率组合,其中,每个滑移率组合包含一个前轴滑移率和一个后轴滑移率;
    在所述多个滑移率组合中,选择前轴滑移率和后轴滑移率小于0的至少一个滑移率组合;
    在所述至少一个滑移率组合中选择前轴滑移率的绝对值和后轴滑移率的绝对值之和最小的目标滑移率组合;
    确定所述目标滑移率组合中的前轴滑移率为所述前轴目标滑移率,并确定所述目标滑移率组合中的后轴滑移率为所述后轴目标滑移率。
  10. 如权利要求1-9任一项所述的方法,其特征在于,
    所述前轴目标扭矩符合以下公式:
    Figure PCTCN2020080531-appb-100005
    所述后轴目标扭矩符合以下公式:
    Figure PCTCN2020080531-appb-100006
    其中,T f(t)为所述前轴目标扭矩,T f0为所述前轴初始扭矩,e λf(t)为所述前轴目标滑移率和所述前轴实际滑移率的差值,T r(t)为所述后轴目标扭矩,T r0为所述后轴初始扭矩,e λr(t)为所述后轴目标滑移率和所述后轴实际滑移率的差值,K P为比例模块增益系数,K I为积分模块增益系数,K D为微分模块增益系数,t 0为所述车辆的状态为失稳的时刻,t为当前时刻。
  11. 一种控制车辆稳定性的设备,其特征在于,包括:
    获取单元,用于在车辆的状态为失稳时,获取当前时刻所述车辆的需求横摆力矩、前轴实际滑移率、后轴实际滑移率,以及前轴初始扭矩和后轴初始扭矩;
    确定单元,用于确定所述车辆的横摆力矩与前轴滑移率、后轴滑移率的对应关系;以及根据确定的所述横摆力矩与前轴滑移率、后轴滑移率的对应关系,以及所述需求横摆力矩,确定前轴目标滑移率和后轴目标滑移率;
    扭矩计算单元,用于根据所述前轴目标滑移率和所述前轴实际滑移率的差值,以及所述前轴初始扭矩,确定前轴目标扭矩;以及根据所述后轴目标滑移率和所述后轴实际滑移率的差值,以及所述后轴初始扭矩,确定后轴目标扭矩;
    稳定性控制单元,用于根据所述前轴目标扭矩和所述后轴目标扭矩,对所述车辆进行稳定性控制。
  12. 如权利要求11所述的设备,其特征在于,所述设备还包括状态确定单元,用于:
    获取所述当前时刻所述车辆的纵向车速、车轮转向角和实际横摆角速度;
    根据所述纵向车速、所述车轮转向角以及存储的转向特性因数,确定目标横摆角速度,其中,所述转向特性因数用于表征所述车辆的转向特性的常量;
    计算所述实际横摆角速度与所述目标横摆角速度之间的角速度误差;
    若所述角速度误差未落入预设阈值区间内,确定所述车辆的状态为失稳,其中,所述预设阈值区间为所述第一阈值和所述第二阈值构成的区间,其中,所述第一阈值为正数,所述第二阈值为负数。
  13. 如权利要求12所述的设备,其特征在于,所述目标横摆角速度符合以下公式:
    Figure PCTCN2020080531-appb-100007
    其中,γ d(t)为所述目标横摆角速度,v x(t)为所述纵向车速,δ(t)为所述车轮转向角,l f为所述车辆的质心到前轴的距离,l r为所述车辆的质心到后轴的距离,K为所述转向特性因数,t为当前时刻。
  14. 如权利要求12或13所述的设备,其特征在于,所述获取单元,在获取所述需求横摆力矩时,具体用于:
    根据所述角速度误差,确定所述需求横摆力矩。
  15. 如权利要求14所述的设备,其特征在于,
    当所述角速度误差大于所述第一阈值时,所述需求横摆力矩符合以下公式:
    Figure PCTCN2020080531-appb-100008
    当所述角速度误差小于所述第二阈值时,所述需求横摆力矩符合以下公式:
    Figure PCTCN2020080531-appb-100009
    其中,M(t)为所述需求横摆力矩,sign(δ(t))为符号函数,δ(t)为所述车轮转向角,e γ(t)为所述实际横摆角速度与所述目标横摆角速度的差值,K Po为所述车辆在过多转向工况时的比例模块增益系数,K Io为所述车辆在过多转向工况时的积分模块增益系数、K Do所述车辆在过多转向工况时的微分模块增益系数,t 0为所述车辆的状态为失稳的时刻,t为当前时刻,K Pu为所述车辆在不足转向工况时的比例模块增益系数,K Iu所述车辆在不足转向工况时的积分模块增益系数、K Du所述车辆在不足转向工况时的微分模块增益系数。
  16. 如权利要求12-15任一项所述的设备,其特征在于,所述角速度误差符合以下公式:
    Figure PCTCN2020080531-appb-100010
    其中,e γ(t)为所述角速度误差,γ(t)为所述实际横摆角速度,γ d(t)为所述目标横摆角速度。
  17. 如权利要求11-16任一项所述的设备,其特征在于,所述确定单元,在确定所述车辆的横摆力矩与前轴滑移率、后轴滑移率的对应关系时,具体用于:
    获取所述当前时刻所述车辆的车轮转向角、前轴侧偏角、后轴侧偏角、前轴垂向力以及后轴垂向力;
    根据所述车轮转向角、所述前轴侧偏角、所述后轴侧偏角、所述前轴垂向力以及所述后轴垂向力,建立所述横摆力矩与前轴滑移率、后轴滑移率的对应关系。
  18. 如权利要求17所述的设备,其特征在于,所述横摆力矩与前轴滑移率、后轴滑移率的对应关系符合以下公式:
    M=cosδ(C 1ffd|+C 0ffF zfl f-(C 1rrd|+C 0rrF zrl r
    其中,M为横摆力矩,δ为车轮转向角,C 1f和C 0f为前轴等效轮胎模型线性化系数,C 1r和C 0r为后轴等效轮胎线性化系数,λ fd为前轴滑移率,λ rd为后轴滑移率,α f为前轴侧偏角,α r为后轴侧偏角,F zf为前轴垂向力,F zr为后轴垂向力,l f为车辆的质心到前轴的距离,l r为车辆的质心到后轴的距离。
  19. 如权利要求18所述的设备,其特征在于,所述确定单元,在根据确定的所述横摆力矩与前轴滑移率、后轴滑移率的对应关系,以及所述需求横摆力矩,确定前轴目标滑移率和后轴目标滑移率时,具体用于:
    根据所述横摆力矩与前轴滑移率、后轴滑移率的对应关系,以及所述需求横摆力矩,确定多个滑移率组合,其中,每个滑移率组合包含一个前轴滑移率和一个后轴滑移率;
    在所述多个滑移率组合中,选择前轴滑移率和后轴滑移率小于0的至少一个滑移率组合;
    在所述至少一个滑移率组合中选择前轴滑移率的绝对值和后轴滑移率的绝对值之和最小的目标滑移率组合;
    确定所述目标滑移率组合中的前轴滑移率为所述前轴目标滑移率,并确定所述目标滑移率组合中的后轴滑移率为所述后轴目标滑移率。
  20. 如权利要求11-19任一项所述的设备,其特征在于,
    所述前轴目标扭矩符合以下公式:
    Figure PCTCN2020080531-appb-100011
    所述后轴目标扭矩符合以下公式:
    Figure PCTCN2020080531-appb-100012
    其中,T f(t)为所述前轴目标扭矩,T f0为所述前轴初始扭矩,e λf(t)为所述前轴目标滑移率和所述前轴实际滑移率的差值,T r(t)为所述后轴目标扭矩,T r0为所述后轴初始扭矩,e λr(t)为所述后轴目标滑移率和所述后轴实际滑移率的差值,K P为比例模块增益系数,K I为积分模块增益系数,K D为微分模块增益系数,t 0为所述车辆的状态为失稳的时刻,t为当前时刻。
  21. 一种控制车辆稳定性的设备,其特征在于,包括:
    存储器,用于存储程序指令;
    通信接口,用于接收和发送数据;
    处理器,用于调用存储在所述存储器中的所述程序指令,通过所述通信接口执行如权利要求1-10任一项所述的方法。
  22. 一种计算机程序,其特征在于,当所述计算机程序在计算机上运行时,使得所述计算机执行如权利要求1-10任一项所述的方法。
  23. 一种计算机存储介质,其特征在于,所述计算机存储介质中存储有计算机程序,当所述计算机程序被计算机执行时,使得所述计算机执行如权利要求1-10任一项所述的方法。
  24. 一种芯片,其特征在于,所述芯片用于读取存储器中存储的计算机程序,执行如权利要求1-10任一项所述的方法。
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