Method and device for estimating longitudinal speed of vehicle

Abstract

The invention discloses a longitudinal speed estimation method and device of a vehicle. According to the scheme, the driving state parameters of a vehicle at the current moment and the longitudinal vehicle speed of the vehicle at the previous moment are obtained; the driving state parameters comprise the longitudinal acceleration of the vehicle and the wheel speed of each wheel; determining the wheel state of the vehicle at the current moment based on the driving state parameter at the current moment and the longitudinal vehicle speed at the previous moment; the wheel state is used for representing whether each wheel slips or not; determining a vehicle speed estimation mode matched with the wheel state from a plurality of preset vehicle speed estimation modes based on the wheel state; and estimating the longitudinal vehicle speed of the vehicle at the current moment based on the vehicle speed estimation mode and the driving state parameters. According to the technical scheme, the longitudinal vehicle speed of the vehicle at the current moment is determined through the vehicle speed estimation mode matched with the wheel state, and the accuracy of longitudinal vehicle speed estimation of the vehicle is improved.

Description

Technical Field

[0001] The present application relates to the technical field of vehicle power control, and in particular to a method and device for estimating the longitudinal speed of a vehicle. Background Art

[0002] With the development of vehicle power control technology, vehicle dynamics control plays an important role in vehicle driving performance and safety performance. Dynamics performance has become one of the key indicators that users consider when buying a car. The longitudinal speed of the vehicle is an important state parameter of vehicle dynamics control. Accurate longitudinal speed is essential for achieving key functions such as drive anti-skid, brake lock, and handling stability control.

[0003] At present, the prior art usually adopts a kinematic estimation method to estimate the longitudinal speed of a vehicle by processing signals such as wheel speed signals and inertial measurement unit signals (such as acceleration signals, angular velocity signals, etc.) to obtain the longitudinal speed of the vehicle. However, since the vehicle is prone to wheel slippage, signal interference and noise during driving, the accuracy of the longitudinal speed of the vehicle obtained based on the wheel speed signal and the inertial measurement unit signal is low, which affects the driving performance and safety performance of the vehicle and leads to a low driving experience for users. Summary of the invention

[0004] Based on the above problems, the present application provides a method and device for estimating the longitudinal speed of a vehicle, the purpose of which is to improve the accuracy of estimating the longitudinal speed of the vehicle.

[0005] The embodiments of the present application disclose the following technical solutions:

[0006] In a first aspect of the present application, a method for estimating the longitudinal speed of a vehicle is provided, the method comprising:

[0007] Obtaining the vehicle's current driving state parameters and the vehicle's previous longitudinal speed; the driving state parameters include the vehicle's longitudinal acceleration and the wheel speed of each wheel;

[0008] Based on the driving state parameters at the current moment and the longitudinal vehicle speed at the previous moment, the wheel state of the vehicle at the current moment is determined; the wheel state is used to indicate whether each wheel has wheel slip;

[0009] Determining a vehicle speed estimation method that matches the wheel state from a plurality of preset vehicle speed estimation methods based on the wheel state;

[0010] The longitudinal speed of the vehicle at the current moment is estimated based on the vehicle speed estimation method and the driving state parameters.

[0011] In an optional implementation, determining the wheel state of the vehicle at the current moment based on the driving state parameter at the current moment and the longitudinal vehicle speed at the previous moment includes:

[0012] Derivative the wheel speed of each wheel to obtain the acceleration of each wheel;

[0013] Determine the slip rate of each wheel according to the wheel speed of each wheel and the longitudinal vehicle speed at the last moment;

[0014] The wheel state is determined based on the acceleration of each wheel, the longitudinal acceleration, and the slip ratio of each wheel.

[0015] In an optional implementation, determining the wheel state based on the acceleration of each wheel, the longitudinal acceleration and the slip rate of each wheel includes:

[0016] Determining the difference between the acceleration of each wheel and the longitudinal acceleration;

[0017] Determine whether the difference corresponding to each wheel is less than a first preset threshold;

[0018] If the difference corresponding to the wheel is less than the first preset threshold, determining whether the slip rate of each wheel is less than the slip rate threshold;

[0019] If the slip rate of the wheel is less than the slip rate threshold, the wheel is determined to be a target wheel; the target wheel is a wheel that has not experienced wheel slip;

[0020] The wheel status is determined based on the number of target wheels.

[0021] In an optional implementation, determining the wheel state based on the number of target wheels includes:

[0022] Determining whether the number of target wheels is greater than a first preset value;

[0023] If the number of target wheels is greater than a first preset value, the wheel state is determined to be a first state; the first state is used to indicate that no wheel slip occurs on any of the wheels.

[0024] In an optional implementation, the method for estimating the longitudinal speed of the vehicle further includes:

[0025] If the difference corresponding to the wheel is greater than or equal to the first preset threshold, or the slip rate of the wheel is greater than or equal to the slip rate threshold, the wheel is determined to be a non-target wheel; the non-target wheel is a wheel where wheel slip occurs;

[0026] The wheel status is determined based on the number of non-target wheels.

[0027] In an optional implementation, determining the wheel state based on the number of non-target wheels includes:

[0028] Determining whether the number of non-target wheels is greater than a second preset value;

[0029] If the number of non-target wheels is greater than a second preset value, the wheel state is determined to be a second state; the second state is used to indicate that all wheels are slipping;

[0030] If the number of non-target wheels is less than or equal to the second preset value, the wheel state is determined to be the third state; the third state is used to indicate that some wheels of the vehicle are slipping.

[0031] In an optional implementation, when the wheel state is the first state, the vehicle speed estimation method is determined to be the first vehicle speed estimation method; the first vehicle speed estimation method is used to determine the longitudinal vehicle speed of the vehicle at the current moment based on the wheel speed of each wheel;

[0032] The longitudinal speed of the vehicle at the current moment is estimated based on the vehicle speed estimation method and the driving state parameters, including:

[0033] The average speed of the vehicle wheels is determined based on the wheel speeds of the individual wheels, and the average speed is used as the longitudinal speed of the vehicle at the current moment.

[0034] In an optional implementation, when the wheel state is the second state, the vehicle speed estimation method is determined to be the second vehicle speed estimation method; the second vehicle speed estimation method is used to determine the longitudinal vehicle speed of the vehicle at the current moment based on the acceleration-integrated vehicle speed, the wheel speeds of each wheel, and the driving condition of the vehicle; the acceleration-integrated vehicle speed is the speed obtained by integrating the longitudinal acceleration of the vehicle; the driving condition includes a driving condition and a braking condition;

[0035] The longitudinal speed of the vehicle at the current moment is estimated based on the vehicle speed estimation method and the driving state parameters, including:

[0036] If the vehicle's driving condition is a driving condition, the minimum value of the acceleration-integrated vehicle speed and the wheel speed of each wheel is taken as the longitudinal vehicle speed of the vehicle at the current moment;

[0037] If the driving condition of the vehicle is a braking condition, the maximum value of the acceleration-integrated vehicle speed and the wheel speed of each wheel is taken as the longitudinal vehicle speed of the vehicle at the current moment.

[0038] In an optional implementation, when the wheel state is the third state, the vehicle speed estimation method is determined to be the third vehicle speed estimation method; the third vehicle speed estimation method is used to determine the longitudinal vehicle speed at the current moment according to the wheel speed and slip state of each wheel; the slip state is used to characterize the condition of wheel slippage of each wheel;

[0039] The longitudinal speed of the vehicle at the current moment is estimated based on the vehicle speed estimation method and the driving state parameters, including:

[0040] determining a wheel speed of a target wheel based on the slip state and the wheel speeds of the respective wheels;

[0041] The longitudinal speed of the vehicle at the current moment is estimated based on the wheel speed of the target wheel.

[0042] In an optional implementation, when the wheel state is the second state, the method for estimating the longitudinal speed of the vehicle further includes:

[0043] monitoring whether a difference between the average speed and the wheel speed of each wheel is less than a second preset threshold, and whether a difference between the longitudinal acceleration of the vehicle and the acceleration of each wheel is less than a third preset threshold;

[0044] If the difference between the average speed and the wheel speed of each wheel is less than the second preset threshold, and the difference between the longitudinal acceleration of the vehicle and the acceleration of each wheel is less than the third preset threshold, it is determined that the wheel state of the vehicle is switched from the second state to the first state, and the average speed is used as the longitudinal speed of the vehicle at the target time; the target time is the time when the wheel state of the vehicle is switched from the second state to the first state.

[0045] In an optional implementation, the method for estimating the longitudinal speed of the vehicle further includes:

[0046] When the wheel state of the vehicle is switched from the second state to the first state, the longitudinal speed of the vehicle in the second state is smoothly transitioned to the longitudinal speed in the first state.

[0047] In a second aspect of the present application, a device for estimating the longitudinal speed of a vehicle is provided, the device comprising:

[0048] An acquisition module, used to acquire the vehicle's driving state parameters at the current moment and the vehicle's longitudinal speed at the previous moment; the driving state parameters include the vehicle's longitudinal acceleration and the wheel speed of each wheel;

[0049] The wheel state determination module is used to determine the wheel state of the vehicle at the current moment based on the driving state parameters at the current moment and the longitudinal vehicle speed at the previous moment; the wheel state is used to indicate whether each wheel has wheel slip;

[0050] A vehicle speed estimation mode determination module, used to determine a vehicle speed estimation mode matching the wheel state from a plurality of preset vehicle speed estimation modes based on the wheel state;

[0051] The vehicle speed estimation module is used to estimate the longitudinal speed of the vehicle at the current moment based on the vehicle speed estimation method and the driving state parameters.

[0052] Compared with the prior art, this application has the following beneficial effects:

[0053] In the technical solution of the present application, firstly, the driving state parameters of the vehicle at the current moment and the longitudinal speed of the vehicle at the previous moment are obtained, and based on the driving state parameters of the vehicle at the current moment and the longitudinal speed of the vehicle at the previous moment, the wheel state of the vehicle at the current moment is determined, so as to accurately determine whether wheel slip (i.e., wheel state) occurs on each wheel at the current moment; then, based on the wheel state, a speed estimation method matching the wheel state is determined from a plurality of preset speed estimation methods, so as to accurately determine a speed estimation method matching the wheel state from a plurality of preset speed estimation methods; thus, based on the driving state parameters and the accurate speed estimation method, the longitudinal speed of the vehicle at the current moment can be accurately estimated, so as to solve the technical problem of low accuracy of longitudinal speed estimation of the vehicle existing in the prior art, thereby improving the driving performance and safety performance of the vehicle, and improving the driving experience of the user. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0055] Figure 1 A flowchart of a method for estimating the longitudinal speed of a vehicle provided in an embodiment of the present application;

[0056] Figure 2 A flowchart of another method for estimating the longitudinal speed of a vehicle provided in an embodiment of the present application;

[0057] Figure 3 A flowchart of a process for determining a wheel state provided in an embodiment of the present application;

[0058] Figure 4 A flowchart of another process for determining a wheel state provided in an embodiment of the present application;

[0059] Figure 5 A flowchart of another process for determining a wheel state provided in an embodiment of the present application;

[0060] Figure 6 A schematic diagram of the structure of a device for estimating the longitudinal speed of a vehicle provided in an embodiment of the present application. DETAILED DESCRIPTION

[0061] As described above, the current existing technology usually uses a kinematic estimation method to estimate the longitudinal speed of a vehicle by processing signals such as wheel speed signals and inertial measurement unit signals (such as acceleration signals, angular velocity signals, etc.) to obtain the longitudinal speed of the vehicle. However, since the vehicle is prone to wheel slippage, signal interference and noise during driving, the accuracy of the longitudinal speed of the vehicle obtained based on the wheel speed signal and inertial measurement unit signal is low, which affects the driving performance and safety performance of the vehicle and leads to a low driving experience for users.

[0062] After research, the inventor proposed to obtain the driving state parameters of the vehicle at the current moment and the longitudinal speed of the vehicle at the previous moment, and determine the wheel state of the vehicle at the current moment based on the driving state parameters of the vehicle at the current moment and the longitudinal speed of the vehicle at the previous moment, so as to accurately determine whether each wheel is slipping (i.e., the wheel state) at the current moment; proposed to determine a speed estimation method that matches the wheel state from multiple preset speed estimation methods based on the wheel state, so as to accurately determine a speed estimation method that matches the wheel state from multiple preset speed estimation methods; thereby, based on the driving state parameters and the accurate speed estimation method, the longitudinal speed of the vehicle at the current moment can be accurately estimated, which solves the technical problem of low accuracy of longitudinal speed estimation of the vehicle in the prior art, thereby improving the driving performance and safety performance of the vehicle as well as the driving experience of the user.

[0063] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0064] Method Embodiment

[0065] An embodiment of the present application provides an embodiment of a method for estimating the longitudinal speed of a vehicle. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0066] See also Figure 1 , which is a flow chart of a method for estimating the longitudinal speed of a vehicle provided in an embodiment of the present application, the method comprising the following steps:

[0067] Step S101, obtaining the driving state parameters of the vehicle at the current moment and the longitudinal speed of the vehicle at the previous moment.

[0068] In an optional embodiment, a vehicle longitudinal speed estimation system can be used as the execution body of the vehicle longitudinal speed estimation method of the embodiment of the present application. For the convenience of description, the vehicle longitudinal speed estimation system is referred to as a system below.

[0069] In step S101, the driving state parameters include the longitudinal acceleration of the vehicle and the wheel speed of each wheel. The wheel speed of each wheel may be the linear speed of the wheel collected by a wheel speed sensor or other equipment, and the longitudinal acceleration is acceleration data collected by an acceleration sensor or other equipment.

[0070] In the embodiments of the present application, Figure 2 As shown, by obtaining the longitudinal acceleration a of the vehicle at the current moment x The wheel speed of each wheel and the longitudinal speed of the vehicle at the previous moment can accurately reflect the wheel status of each wheel of the vehicle through the longitudinal acceleration and the wheel speed of each wheel, combined with the reference value of the longitudinal speed of the vehicle at the previous moment, thereby providing data preparation for accurately estimating the longitudinal speed of the vehicle at the current moment.

[0071] Step S102, determining the wheel state of the vehicle at the current moment based on the driving state parameters at the current moment and the longitudinal vehicle speed at the previous moment.

[0072] In step S102, the wheel status is used to characterize whether each wheel has wheel slip. In the scenario where the vehicle is a four-wheel drive vehicle, the wheel status can be used to characterize whether each wheel of the four-wheel drive vehicle has wheel slip. For example, the wheel status can be used to characterize that three wheels of the four-wheel drive vehicle have wheel slip, wherein the wheels having wheel slip are the left front wheel, the right front wheel, and the right rear wheel of the four-wheel drive vehicle.

[0073] In order to accurately determine whether each wheel of the vehicle is slipping at the current moment (i.e., the wheel state of the vehicle at the current moment), in this embodiment, the system can determine the wheel state of the vehicle at the current moment through the longitudinal acceleration of the vehicle at the current moment, the wheel speed of each wheel, and the longitudinal speed of the vehicle at the previous moment. Figure 3 , which is a flow chart of a process for determining a wheel state provided in an embodiment of the present application, and the process includes the following steps:

[0074] Step S301, deriving the wheel speed of each wheel respectively to obtain the acceleration of each wheel.

[0075] In the embodiment of the present application, the system can obtain the acceleration of each wheel through the formula (1) shown below.

[0076]

[0077] Among them, a i is the acceleration of the ith wheel; V i is the wheel speed of the ith wheel (eg, the linear speed of the ith wheel).

[0078] Step S302, determining the slip rate of each wheel according to the wheel speed of each wheel and the longitudinal vehicle speed at the last moment.

[0079] In the embodiment of the present application, the system can obtain the slip rate of each wheel through the formula (2) shown below.

[0080]

[0081] Among them, S i is the slip rate of the i-th wheel; V x -1 is the longitudinal speed of the vehicle at the previous moment; V i is the wheel speed of the ith wheel.

[0082] Step S303: determining the wheel state based on the acceleration of each wheel, the longitudinal acceleration and the slip rate of each wheel.

[0083] In order to avoid the problem that it is impossible to accurately determine whether each wheel is slipping due to the vehicle being in a wheel locking state, and to improve the accuracy of determining whether each wheel of the vehicle is slipping at the current moment, in this embodiment, the system can determine whether each wheel of the vehicle is slipping (i.e., wheel state) at the current moment through the difference between the acceleration and longitudinal acceleration of each wheel and the slip rate of each wheel. Figure 4 , which is a flowchart of another process for determining a wheel state provided in an embodiment of the present application, the process includes the following steps:

[0084] Step S401, respectively determining the difference between the acceleration of each wheel and the longitudinal acceleration.

[0085] In this embodiment, if Figure 2 As shown, if the longitudinal acceleration of the vehicle is a x , the acceleration of the i-th wheel is a i , then the above difference can be expressed as |a i -a x |.

[0086] Step S402, determining whether the difference corresponding to each wheel is less than a first preset threshold.

[0087] In this embodiment, the first preset threshold is a pre-set threshold for characterizing the wheel slip state. The system can quickly and accurately determine whether each wheel is slipping by judging whether the difference corresponding to each wheel is less than the first preset threshold.

[0088] Step S403: if the difference corresponding to the wheel is less than the first preset threshold, it is determined whether the slip rate of each wheel is less than the slip rate threshold.

[0089] In this embodiment, the slip rate threshold is a preset threshold for determining whether a wheel is slipping. The system can accurately determine whether each wheel is slipping by judging whether the slip rate of each wheel is less than the slip rate threshold.

[0090] Step S404: if the slip rate of the wheel is less than the slip rate threshold, the wheel is determined to be a target wheel.

[0091] In step S403, the target wheel is a wheel that has no wheel slip.

[0092] For example, when the difference corresponding to the left front wheel of the four-wheel drive vehicle is smaller than the first preset threshold and the slip rate of the wheel is smaller than the slip rate threshold, the system can determine that the left front wheel does not slip.

[0093] Step S405, determining the wheel status based on the number of target wheels.

[0094] In this embodiment, the system can determine the wheel state of the vehicle by determining whether the number of target wheels is greater than a first preset value. Specifically, the system can determine whether the number of target wheels is greater than the first preset value; if the number of target wheels is greater than the first preset value, the system can determine that the wheel state is the first state; the first state is used to indicate that no wheel slip occurs on each wheel.

[0095] For example, in a scenario where the vehicle is a four-wheel drive vehicle, Figure 2 As shown, the first preset value is set to 3. If the system determines that the number of target wheels is 4, the system can determine that no wheel slip occurs on each wheel of the vehicle.

[0096] Alternatively, see Figure 5 , which is a flowchart of another process for determining a wheel state provided in an embodiment of the present application, the process includes the following steps:

[0097] Step S501: If the difference corresponding to the wheel is greater than or equal to a first preset threshold, or the slip rate of the wheel is greater than or equal to a slip rate threshold, the wheel is determined to be a non-target wheel.

[0098] In step S501, the non-target wheel is a wheel where wheel slip occurs.

[0099] Step S502: determining the wheel status based on the number of non-target wheels.

[0100] For example, if the difference corresponding to the left rear wheel of a four-wheel drive vehicle is greater than or equal to a first preset threshold, the system can determine that the left rear wheel is the wheel where wheel slippage occurs; or if the slip rate corresponding to the left rear wheel of the four-wheel drive vehicle is greater than or equal to a slip rate threshold, the system can determine that the left rear wheel is the wheel where wheel slippage occurs.

[0101] In this embodiment, the system can determine the wheel state of the vehicle by judging whether the number of non-target wheels is greater than a second preset value; if the number of non-target wheels is greater than the second preset value, the system determines that the wheel state is the second state, wherein the second state is used to characterize that wheel slip occurs on all wheels; if the number of non-target wheels is less than or equal to the second preset value, the system determines that the wheel state is the third state, wherein the third state is used to characterize that wheel slip occurs on some wheels of the vehicle.

[0102] For example, in a scenario where the vehicle is a four-wheel drive vehicle, Figure 2 As shown, the second preset value is set to 3. If the system determines that the number of non-target wheels is 4, the system can determine that all wheels of the vehicle are slipping; if the number of non-target wheels is 2, the system can determine that some wheels of the vehicle are slipping.

[0103] Step S103, determining a vehicle speed estimation method that matches the wheel state from a plurality of preset vehicle speed estimation methods based on the wheel state.

[0104] In step S103 , the correspondence between the wheel states and a plurality of preset vehicle speed estimation methods may be as shown in Table 1.

[0105] Table 1

[0106]

[0107] In order to accurately determine the vehicle speed estimation method that matches the wheel state, in an embodiment of the present application, the system can determine the vehicle speed estimation method that matches the wheel state from multiple preset vehicle speed estimation methods based on the wheel state. For example, when the wheel state is a first state, the system can determine the vehicle speed estimation method that matches the first state from multiple preset vehicle speed estimation methods as the first vehicle speed estimation method.

[0108] Step S104, estimating the longitudinal speed of the vehicle at the current moment based on the vehicle speed estimation method and the driving state parameters.

[0109] In order to accurately estimate the longitudinal speed of the vehicle at the current moment, thereby solving the technical problem of low accuracy of the longitudinal speed estimation of the vehicle in the prior art, in an embodiment of the present application, the system can estimate the longitudinal speed of the vehicle at the current moment based on the speed estimation method and driving state parameters.

[0110] Specifically, Figure 2 As shown, when the wheel state is the first state, the system can determine that the vehicle speed estimation method is the first vehicle speed estimation method; the first vehicle speed estimation method is used to determine the longitudinal vehicle speed of the vehicle at the current moment based on the wheel speed of each wheel; the system estimates the longitudinal vehicle speed of the vehicle at the current moment based on the vehicle speed estimation method and the driving state parameters, including: the system can determine the average speed of the vehicle wheels based on the wheel speed of each wheel, and use the average speed as the longitudinal vehicle speed of the vehicle at the current moment.

[0111] For example, in a scenario where the vehicle is a four-wheel drive vehicle, the system can determine the average speed of the vehicle wheels by the following formula (3).

[0112]

[0113] Among them, V x，av is the average speed of the vehicle wheels; V i is the wheel speed of the ith wheel.

[0114] Alternatively, if Figure 2 As shown, when the wheel state is the second state, the system can determine that the vehicle speed estimation method is the second vehicle speed estimation method; wherein the second vehicle speed estimation method is used to determine the longitudinal vehicle speed of the vehicle at the current moment based on the acceleration-integrated vehicle speed, the wheel speed of each wheel and the driving condition of the vehicle; the acceleration-integrated vehicle speed is the speed obtained by integrating the longitudinal acceleration of the vehicle; the driving condition includes the driving condition and the braking condition. The system estimates the longitudinal vehicle speed of the vehicle at the current moment based on the vehicle speed estimation method and the driving state parameters, including: if the driving condition of the vehicle is the driving condition, the system can use the minimum value of the acceleration-integrated vehicle speed and the wheel speed of each wheel as the longitudinal vehicle speed of the vehicle at the current moment; if the driving condition of the vehicle is the braking condition, the system can use the maximum value of the acceleration-integrated vehicle speed and the wheel speed of each wheel as the longitudinal vehicle speed of the vehicle at the current moment.

[0115] In this embodiment, the driving condition can be used to characterize the state of the vehicle in the process of acceleration, cruising and normal driving, and the braking condition is used to characterize the state in the process of deceleration. For example, in the scenario where the vehicle is a four-wheel drive vehicle, if the vehicle is in the acceleration state, the system can use the minimum value of the acceleration-integrated vehicle speed and the wheel speed of each wheel as the longitudinal vehicle speed of the vehicle at the current moment; if the vehicle is in the deceleration state, the system can use the maximum value of the acceleration-integrated vehicle speed and the wheel speed of each wheel as the longitudinal vehicle speed of the vehicle at the current moment.

[0116] It should be noted that when all wheels of the vehicle are slipping, by determining the longitudinal speed of the vehicle at the current moment based on the driving condition of the vehicle, the longitudinal speed of the vehicle at the current moment under different driving conditions can be accurately estimated, thereby improving the accuracy of the longitudinal speed estimation of the vehicle.

[0117] Alternatively, if Figure 2 As shown, when the wheel state is the third state, the system can determine that the vehicle speed estimation method is the third vehicle speed estimation method; the third vehicle speed estimation method is used to determine the longitudinal vehicle speed at the current moment according to the wheel speed and slip state of each wheel; the slip state is used to characterize the condition of wheel slippage of each wheel; the system estimates the longitudinal vehicle speed of the vehicle at the current moment based on the vehicle speed estimation method and the driving state parameters, including: the system can determine the wheel speed of the target wheel based on the slip state and the wheel speed of each wheel; the system can estimate the longitudinal vehicle speed of the vehicle at the current moment based on the wheel speed of the target wheel.

[0118] In this embodiment, the system can estimate the longitudinal speed of the vehicle at the current moment by using the following formula (4).

[0119]

[0120] Among them, V x，b is the longitudinal speed of the vehicle at the current moment; b i is the slip state of the i-th wheel, where if the wheel slips, then b i = 0, if the wheel does not slip, then b i = 1. For example, if the left front wheel of the vehicle has wheel slip, but the left rear wheel, right front wheel and right rear wheel do not have wheel slip, the system may use the average of the wheel speeds of the left rear wheel, right front wheel and right rear wheel as the longitudinal speed of the vehicle at the current moment; if the left rear wheel, right front wheel and right rear wheel of the vehicle have wheel slip, but the left front wheel of the vehicle does not have wheel slip, the system may use the wheel speed of the left front wheel as the longitudinal speed of the vehicle at the current moment.

[0121] It should be noted that since the wheel speed of the wheel without wheel slip (i.e., the target wheel) can more truly reflect the actual driving speed of the vehicle, determining the longitudinal speed of the vehicle at the current moment through the wheel speed of the target wheel can improve the accuracy of the vehicle's longitudinal speed estimation.

[0122] In the prior art, when the wheel state of a vehicle switches from a state where all tires are slipping (i.e., the second state) to a state where all tires are not slipping (i.e., the first state), it is usually determined whether each wheel has exited the wheel slipping state by monitoring the vehicle's acceleration-integrated vehicle speed. However, since the acceleration-integrated vehicle speed is the vehicle speed obtained by integrating the longitudinal acceleration of the vehicle, when each wheel of the vehicle slips for a long time, the vehicle speed obtained by integrating the longitudinal acceleration of the vehicle gradually deviates from the true value, resulting in the inability of each wheel of the vehicle to exit the wheel slipping state in time, thereby resulting in the inability to timely and accurately estimate the longitudinal vehicle speed of the vehicle.

[0123] In order to solve the above problem, in an embodiment of the present application, when the wheel state is the second state, the system can monitor whether the difference between the average speed of the vehicle wheels and the wheel speed of each wheel is less than the second preset threshold, and whether the difference between the longitudinal acceleration of the vehicle and the acceleration of each wheel is less than the third preset threshold; if the difference between the average speed and the wheel speed of each wheel is less than the second preset threshold, and the difference between the longitudinal acceleration of the vehicle and the acceleration of each wheel is less than the third preset threshold, the system can determine that the wheel state of the vehicle is switched from the second state to the first state, and use the average speed as the longitudinal speed of the vehicle at the target time; wherein the target time is the time when the wheel state of the vehicle switches from the second state to the first state.

[0124] In this embodiment, the system can determine whether each wheel has exited the wheel slip state (i.e., whether the wheel state of the vehicle has switched from the second state to the first state) by monitoring in real time whether the difference between the average speed of the vehicle wheels and the wheel speed of each wheel is less than the second preset threshold, and whether the difference between the longitudinal acceleration of the vehicle and the acceleration of each wheel is less than the third preset threshold; if the vehicle satisfies the condition that the difference between the average speed of the wheels and the wheel speed of each wheel is less than the second preset threshold at the target time, and the difference between the longitudinal acceleration of the vehicle and the acceleration of each wheel is less than the third preset threshold, the system can determine that the wheel state of the vehicle is switched from the second state to the first state, and use the average speed of the wheels as the longitudinal speed of the vehicle at the target time.

[0125] In order to improve the safety and stability of the vehicle, in this embodiment, when the wheel state of the vehicle switches from the second state to the first state, the system can smoothly transition the longitudinal speed of the vehicle in the second state to the longitudinal speed in the first state. Specifically, the system can smoothly transition the longitudinal speed in the second state to the longitudinal speed in the first state through the following formula (5).

[0126] y=A×(1-t)+B×t (5)

[0127] Among them, y is the vehicle speed at time t during the process of smoothly transitioning and adjusting the longitudinal speed of the vehicle; A is the initial longitudinal speed (i.e., the longitudinal speed in the second state); and B is the longitudinal speed in the first state (i.e., the longitudinal speed at the target moment).

[0128] Optionally, in this embodiment, when the wheel state of the vehicle switches from the third state to the first state, the system may smoothly transition the longitudinal speed of the vehicle in the third state to the longitudinal speed in the first state; when the wheel state of the vehicle switches from the second state to the third state, the system may smoothly transition the longitudinal speed of the vehicle in the second state to the longitudinal speed in the third state.

[0129] Through the vehicle longitudinal speed estimation method proposed in the present application, it is possible to accurately determine whether each wheel is slipping (i.e., the wheel state) at the current moment, thereby accurately determining the speed estimation method that matches the wheel state from multiple preset speed estimation methods, and estimating the vehicle's longitudinal speed at the current moment based on the driving state parameters and the accurate speed estimation method, thereby improving the accuracy of the vehicle's longitudinal speed estimation, thereby solving the technical problem of low accuracy in vehicle longitudinal speed estimation in the prior art, and improving the vehicle's driving performance and safety performance as well as the user's driving experience.

[0130] Device Embodiment

[0131] The embodiment of the present application provides a device for estimating the longitudinal speed of a vehicle, wherein: Figure 6 A schematic diagram of the structure of a vehicle longitudinal speed estimation device provided in an embodiment of the present application is shown in FIG. Figure 6 As shown, the device includes: an acquisition module 11, a wheel state determination module 12, a vehicle speed estimation method determination module 13 and a vehicle speed estimation module 14. Figure 6 You can see the connection relationship between several modules.

[0132] The acquisition module 11 is used to acquire the vehicle's driving state parameters at the current moment and the vehicle's longitudinal speed at the previous moment; the driving state parameters include the vehicle's longitudinal acceleration and the wheel speed of each wheel;

[0133] The wheel state determination module 12 is used to determine the wheel state of the vehicle at the current moment based on the driving state parameters at the current moment and the longitudinal vehicle speed at the previous moment; the wheel state is used to indicate whether each wheel has wheel slip;

[0134] A vehicle speed estimation mode determination module 13, configured to determine a vehicle speed estimation mode that matches the wheel state from a plurality of preset vehicle speed estimation modes based on the wheel state;

[0135] The vehicle speed estimation module 14 is used to estimate the longitudinal speed of the vehicle at the current moment based on the vehicle speed estimation method and the driving state parameters.

[0136] Optionally, the wheel state determination module includes: an acceleration calculation unit, a slip ratio determination unit and a wheel state determination unit;

[0137] The acceleration calculation unit is used to respectively derive the wheel speed of each wheel to obtain the acceleration of each wheel;

[0138] A slip ratio determination unit, used to determine the slip ratio of each wheel according to the wheel speed of each wheel and the longitudinal vehicle speed at a previous moment;

[0139] The wheel state determination unit is used to determine the wheel state based on the acceleration of each wheel, the longitudinal acceleration and the slip rate of each wheel.

[0140] Optionally, the wheel state determination unit includes: a first determination unit, a first judgment unit, a slip ratio judgment unit, a second determination unit and a third determination unit.

[0141] Wherein, the first determination unit is used to respectively determine the difference between the acceleration of each wheel and the longitudinal acceleration;

[0142] A first judging unit, used to judge whether the difference corresponding to each wheel is less than a first preset threshold;

[0143] a slip rate determination unit, configured to determine whether the slip rate of each wheel is less than a slip rate threshold value if the difference value corresponding to the wheel is less than a first preset threshold value;

[0144] A second determination unit is used to determine that the wheel is a target wheel if the slip rate of the wheel is less than the slip rate threshold; the target wheel is a wheel that does not experience wheel slip;

[0145] The third determining unit is configured to determine the wheel status based on the number of target wheels.

[0146] Optionally, the third determining unit includes: a second judging unit and a fourth determining unit.

[0147] Wherein, the second judgment unit is used to judge whether the number of target wheels is greater than a first preset value;

[0148] The fourth determination unit is used to determine that the wheel state is a first state if the number of target wheels is greater than a first preset value; the first state is used to indicate that no wheel slip occurs on each wheel.

[0149] Optionally, the vehicle longitudinal speed estimation device further includes: a third judgment unit and a fifth determination unit.

[0150] The third judgment unit is used to determine that the wheel is a non-target wheel if the difference corresponding to the wheel is greater than or equal to the first preset threshold, or the slip rate of the wheel is greater than or equal to the slip rate threshold; the non-target wheel is a wheel where wheel slip occurs;

[0151] A fifth determining unit is configured to determine the wheel status based on the number of non-target wheels.

[0152] Optionally, the fifth determining unit includes: a fourth judging unit, a sixth determining unit and a seventh determining unit.

[0153] The fourth judgment unit is used to judge whether the number of non-target wheels is greater than a second preset value;

[0154] a sixth determining unit, configured to determine that the wheel state is a second state if the number of non-target wheels is greater than a second preset value; the second state is used to indicate that all wheels are slipping;

[0155] The seventh determination unit is used to determine that the wheel state is a third state if the number of non-target wheels is less than or equal to a second preset value; the third state is used to indicate that some wheels of the vehicle are slipping.

[0156] Optionally, the vehicle speed estimation module includes: a first determination module, used to determine that the vehicle speed estimation method is a first vehicle speed estimation method when the wheel state is a first state; the first vehicle speed estimation method is used to determine the longitudinal speed of the vehicle at the current moment based on the wheel speed of each wheel; determine the average speed of the vehicle wheels based on the wheel speed of each wheel, and use the average speed as the longitudinal speed of the vehicle at the current moment.

[0157] Optionally, the vehicle speed estimation module further includes: a second determination module and a third determination module.

[0158] The second determination module is used to determine that the vehicle speed estimation method is the second vehicle speed estimation method when the wheel state is the second state; the second vehicle speed estimation method is used to determine the longitudinal vehicle speed of the vehicle at the current moment based on the acceleration-integrated vehicle speed, the wheel speeds of each wheel and the driving condition of the vehicle; the acceleration-integrated vehicle speed is the speed obtained by integrating the longitudinal acceleration of the vehicle; the driving condition includes a driving condition and a braking condition; if the driving condition of the vehicle is a driving condition, the minimum value of the acceleration-integrated vehicle speed and the wheel speeds of each wheel is used as the longitudinal vehicle speed of the vehicle at the current moment;

[0159] The third determination module is used to take the maximum value of the acceleration-integrated vehicle speed and the wheel speed of each wheel as the longitudinal vehicle speed of the vehicle at the current moment if the driving condition of the vehicle is a braking condition.

[0160] Optionally, the vehicle speed estimation module further includes: a fourth determination module and a fifth determination module.

[0161] The fourth determination module is used to determine that the vehicle speed estimation method is the third vehicle speed estimation method when the wheel state is the third state; the third vehicle speed estimation method is used to determine the longitudinal vehicle speed at the current moment according to the wheel speed and slip state of each wheel; the slip state is used to characterize the condition of wheel slip of each wheel; the wheel speed of the target wheel is determined based on the slip state and the wheel speed of each wheel;

[0162] The fifth determination module is used to estimate the longitudinal speed of the vehicle at a current moment based on the wheel speed of the target wheel.

[0163] Optionally, the vehicle speed estimation module further includes: a monitoring module and a switching module.

[0164] The monitoring module is used to monitor whether the difference between the average speed and the wheel speed of each wheel is less than a second preset threshold value, and whether the difference between the longitudinal acceleration of the vehicle and the acceleration of each wheel is less than a third preset threshold value when the wheel state is the second state;

[0165] A switching module is used to determine that the wheel state of the vehicle is switched from the second state to the first state if the difference between the average speed and the wheel speed of each wheel is less than a second preset threshold, and the difference between the longitudinal acceleration of the vehicle and the acceleration of each wheel is less than a third preset threshold, and use the average speed as the longitudinal speed of the vehicle at a target time; the target time is the time when the wheel state of the vehicle is switched from the second state to the first state.

[0166] Optionally, the vehicle speed estimation module further includes: a smooth transition module, which is used to smoothly transition the longitudinal vehicle speed of the vehicle in the second state to the longitudinal vehicle speed in the first state when the wheel state of the vehicle switches from the second state to the first state.

[0167] It should be noted that each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. The device embodiment described above is merely schematic, in which the unit described as a separate component may or may not be physically separated, and the component prompted as a unit may or may not be a physical unit, that is, it may be located in one place, or it may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative work.

[0168] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for estimating the longitudinal speed of a vehicle, characterized in that: include: Acquiring a driving state parameter of the vehicle at a current moment and a longitudinal speed of the vehicle at a previous moment; the driving state parameter includes the longitudinal acceleration of the vehicle and the wheel speed of each wheel; Determining the wheel state of the vehicle at the current moment based on the driving state parameter at the current moment and the longitudinal vehicle speed at the previous moment; The wheel status is used to indicate whether wheel slip occurs on each wheel; Determining a vehicle speed estimation method that matches the wheel state from a plurality of preset vehicle speed estimation methods based on the wheel state; The longitudinal speed of the vehicle at the current moment is estimated based on the vehicle speed estimation method and the driving state parameter.

2. The method according to claim 1, characterized in that: The determining of the wheel state of the vehicle at the current moment based on the driving state parameter at the current moment and the longitudinal vehicle speed at the previous moment includes: Deriving the wheel speed of each wheel respectively to obtain the acceleration of each wheel; Determining the slip rate of each wheel according to the wheel speed of each wheel and the longitudinal vehicle speed at the last moment; The wheel states are determined based on the accelerations of the respective wheels, the longitudinal accelerations, and the slip rates of the respective wheels.

3. The method according to claim 2, characterized in that The determining the wheel state based on the acceleration of each wheel, the longitudinal acceleration and the slip rate of each wheel comprises: respectively determining the difference between the acceleration of each wheel and the longitudinal acceleration; Determine whether the difference corresponding to each wheel is less than a first preset threshold; If the difference corresponding to the wheel is less than the first preset threshold, determining whether the slip rate of each wheel is less than a slip rate threshold; If the slip rate of the wheel is less than the slip rate threshold, the wheel is determined to be a target wheel; the target wheel is a wheel that has not experienced wheel slip; The wheel status is determined based on the number of the target wheels.

4. The method according to claim 3, characterized in that The determining the wheel state based on the number of the target wheels comprises: Determining whether the number of the target wheels is greater than a first preset value; If the number of the target wheels is greater than the first preset value, the wheel state is determined to be a first state; the first state is used to indicate that none of the wheels experience wheel slippage.

5. The method according to claim 4, characterized in that The method further comprises: If the difference corresponding to the wheel is greater than or equal to the first preset threshold, or the slip rate of the wheel is greater than or equal to the slip rate threshold, the wheel is determined to be a non-target wheel; the non-target wheel is the wheel where the wheel slip occurs; The wheel status is determined based on the number of the non-target wheels.

6. The method according to claim 5, characterized in that The determining the wheel state based on the number of the non-target wheels comprises: Determining whether the number of the non-target wheels is greater than a second preset value; If the number of the non-target wheels is greater than the second preset value, the wheel state is determined to be a second state; the second state is used to indicate that the wheel slip occurs on each of the wheels; If the number of the non-target wheels is less than or equal to the second preset value, the wheel state is determined to be a third state; the third state is used to indicate that wheel slip occurs on some wheels of the vehicle.

7. The method according to claim 6, characterized in that When the wheel state is the first state, determining the vehicle speed estimation method to be a first vehicle speed estimation method; the first vehicle speed estimation method is used to determine the longitudinal vehicle speed of the vehicle at the current moment based on the wheel speeds of the respective wheels; The estimating the longitudinal speed of the vehicle at the current moment based on the vehicle speed estimation method and the driving state parameter includes: An average speed of the vehicle wheels is determined based on the wheel speeds of the individual wheels, and the average speed is used as the longitudinal speed of the vehicle at the current moment.

8. The method according to claim 6, characterized in that When the wheel state is the second state, the vehicle speed estimation mode is determined to be the second vehicle speed estimation mode; the second vehicle speed estimation mode is used to determine the longitudinal vehicle speed of the vehicle at the current moment based on the acceleration-integrated vehicle speed, the wheel speeds of the respective wheels, and the driving condition of the vehicle; the acceleration-integrated vehicle speed is the speed obtained by integrating the longitudinal acceleration of the vehicle; the driving condition includes a driving condition and a braking condition; The estimating the longitudinal speed of the vehicle at the current moment based on the vehicle speed estimation method and the driving state parameter includes: If the running condition of the vehicle is the driving condition, taking the minimum value of the acceleration-integrated vehicle speed and the wheel speed of each wheel as the longitudinal vehicle speed of the vehicle at the current moment; If the driving condition of the vehicle is the braking condition, the maximum value of the acceleration-integrated vehicle speed and the wheel speed of each wheel is used as the longitudinal vehicle speed of the vehicle at the current moment.

9. The method according to claim 6, characterized in that When the wheel state is the third state, the vehicle speed estimation method is determined to be the third vehicle speed estimation method; the third vehicle speed estimation method is used to determine the longitudinal vehicle speed at the current moment according to the wheel speed and slip state of each wheel; the slip state is used to characterize the condition in which the wheel slip occurs on each wheel; The estimating the longitudinal speed of the vehicle at the current moment based on the vehicle speed estimation method and the driving state parameter includes: determining the wheel speed of the target wheel based on the slip state and the wheel speeds of the respective wheels; The longitudinal speed of the vehicle at the current moment is estimated based on the wheel speed of the target wheel.

10. The method according to claim 7, characterized in that When the wheel state is the second state, the method further includes: monitoring whether a difference between the average speed and the wheel speed of each wheel is less than a second preset threshold, and whether a difference between the longitudinal acceleration of the vehicle and the acceleration of each wheel is less than a third preset threshold; If the difference between the average speed and the wheel speed of each wheel is less than the second preset threshold, and the difference between the longitudinal acceleration of the vehicle and the acceleration of each wheel is less than the third preset threshold, it is determined that the wheel state of the vehicle is switched from the second state to the first state, and the average speed is used as the longitudinal speed of the vehicle at the target time; the target time is the time when the wheel state of the vehicle is switched from the second state to the first state.

11. The method according to claim 10, characterized in that The method further comprises: When the wheel state of the vehicle is switched from the second state to the first state, the longitudinal speed of the vehicle in the second state is smoothly transitioned to the longitudinal speed of the vehicle in the first state.

12. A device for estimating the longitudinal speed of a vehicle, characterized in that: include: An acquisition module, used to acquire the driving state parameters of the vehicle at the current moment and the longitudinal speed of the vehicle at the previous moment; the driving state parameters include the longitudinal acceleration of the vehicle and the wheel speed of each wheel; A wheel state determination module, used to determine the wheel state of the vehicle at the current moment based on the driving state parameter at the current moment and the longitudinal vehicle speed at the previous moment; The wheel status is used to indicate whether wheel slip occurs on each wheel; a vehicle speed estimation mode determination module, configured to determine a vehicle speed estimation mode matching the wheel state from a plurality of preset vehicle speed estimation modes based on the wheel state; The vehicle speed estimation module is used to estimate the longitudinal speed of the vehicle at the current moment based on the vehicle speed estimation method and the driving state parameter.

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