Drift control method and control unit for vehicle
By calculating the degree of vehicle drift and stability factors and determining the steering control strategy, the problem of difficulty in quickly adjusting the body posture in the prior art is solved, and the stability and safety improvement in the process of vehicle drift is achieved.
Patent Information
- Application Number
- CN202510482783.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-17
- Publication Date
- 2025-06-27
AI Technical Summary
In some cases, existing drift control systems have difficulty adjusting the body posture quickly, resulting in drivers requiring manual correction of steering, increasing safety risks.
By calculating the amount of drift that characterizes the degree of vehicle drift and its change rate, the stability factor is calculated, and the steering control strategy for assisting vehicle drift is determined based on these parameters, including the target steering, target angle and target speed of the steering wheel.
Accurate and timely steering control during vehicle drifting is achieved, the stability during vehicle drifting is improved, and the risk of out-of-control is reduced.
Smart Images
Figure CN120207311A_ABST
Abstract
Description
Technical Field
[0001] The present invention generally relates to the technical field of vehicle control, and in particular to a drift control method and a control unit for a vehicle, and also relates to a corresponding machine-readable storage medium. Background Art
[0002] As an advanced driving technique, drifting is widely used in automotive shows and racing events due to its unique visual appeal and handling challenges, bringing unparalleled driving pleasure to vehicle owners. Existing drift control systems typically monitor vehicle dynamic parameters (such as yaw rate and sideslip angle) in real time and distribute the drive torque of the front and rear axles based on these parameters to control the drifting state of the vehicle. However, there are still some deficiencies in existing drift control systems: in some cases, it is difficult to quickly adjust the vehicle body attitude relying solely on torque distribution, and at this time, the driver needs to manually correct the steering. This intervention requires the driver to have rich driving experience to accurately master the steering amplitude. In addition, the driver's untimely response may lead to vehicle out of control, increasing the safety risk. Summary of the Invention
[0003] In this context, according to an embodiment of one aspect of the present invention, a drift control method for a vehicle is provided, which includes: calculating a value of a drift amount characterizing the degree of vehicle drift and its change rate based on parameters related to the vehicle motion state; calculating a value of a stability factor based on the value of the drift amount and its change rate, where the stability factor represents the risk level of loss of control during vehicle drifting; determining a steering control strategy for assisting vehicle drifting based on the value of the stability factor and the value of the drift amount, where the steering control strategy includes: when the value of the drift amount is greater than a first drift degree threshold, determining the target steering of the steering wheel as the direction opposite to the current vehicle steering, and determining the target steering angle of the steering wheel based on the value of the drift amount; and determining the target rotation speed of the steering wheel based on the target steering angle of the steering wheel and the value of the stability factor.
[0004] According to an embodiment of another aspect of the present invention, a drift control unit for a vehicle is provided, including a memory and one or more processors, the memory storing executable instructions that, when executed by the one or more processors, execute the above-mentioned drift control method.
[0005] According to an embodiment of still another aspect of the present invention, a machine-readable storage medium is provided, which stores executable instructions that, when executed by one or more processors, cause the one or more processors to execute the above-mentioned drift control method.
[0006] According to an embodiment of another aspect of the present invention, there is provided a computer program product including instructions that, when executed by one or more processors, cause the one or more processors to execute the drift control method as described above.
[0007] The above presents an overview of the main aspects of the present invention to provide a basic understanding of these aspects and as a prelude to the detailed description to be given later. BRIEF DESCRIPTION OF THE DRAWINGS
[0008] From the following detailed description in conjunction with the accompanying drawings, the technical solutions of the present invention will become clearer. It can be understood that these drawings are only for illustrative purposes and are not intended to limit the protection scope of the present invention.
[0009] Figure 1 is a schematic diagram of a drift control system for a vehicle according to an embodiment of the present invention.
[0010] Figure 2 is a flowchart of a drift control method for a vehicle according to an embodiment of the present invention.
[0011] Figure 3A and 3B respectively schematically show curves of a first value and a second value of a stability factor.
[0012] Figure 4 schematically shows a first steering mode and a second steering mode.
[0013] Figure 5A and 5B respectively schematically show curves of a first value and a second value of a target rotational speed of a steering wheel. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0014] Next, the specific embodiments of the present invention will be introduced in conjunction with the accompanying drawings.
[0015] Figure 1 schematically shows a drift control system 100 for a vehicle V according to an embodiment of the present invention. The drift control system 100 is provided on the vehicle V, so the drift control system 100 is an in-vehicle system. As Figure 1 shown, the drift control system 100 includes a sensor unit 10, a drift control unit 20, and an execution unit 30.
[0016] The sensor unit 10 includes a plurality of vehicle-mounted sensors for collecting information related to the vehicle drift state and information related to the driver's steering intention. The information related to the vehicle drift state includes, for example: the vehicle traveling direction, the steering of each wheel, the sideslip angle of the center of mass, the rear wheel sideslip angle, the body sideslip angle, the body sideslip angle, the yaw rate, the yaw acceleration, the lateral acceleration, and the tire lateral force. The information related to the driver's steering intention includes, for example, the steering wheel operation information of the driver.
[0017] The sensor unit 10 may include a plurality of vehicle-mounted sensors. For example, the sensor unit 10 is integrated in a multimodal vehicle-mounted sensing system for collecting vehicle drift state parameters and driver steering intention parameters.
[0018] In one embodiment, the information related to the vehicle drift state may include: 1) kinematic characteristic parameters, such as the vehicle traveling direction, the yaw rate, the yaw acceleration, and the lateral acceleration; 2) attitude characteristic parameters: the sideslip angle of the center of mass, the body sideslip angle, the rear wheel sideslip angle, and the tire lateral force; 3) wheel state characteristic parameters, such as the steering angle of each wheel. These parameters can all be measured by corresponding sensors or calculated based on the measurement values of the sensors.
[0019] In one embodiment, the information related to the driver's steering intention may include: the hand torque applied by the driver to the steering wheel, which can be measured by a steering column torque sensor. According to the measured steering wheel hand torque, the following can be obtained: the driver's requested steering direction, for example, determined by the polarity of the hand torque; and the driver's requested steering angle, for example, mapped based on the hand torque amplitude through the transfer function of the steering system.
[0020] The drift control unit 20 is used to execute the steering control method according to the embodiments of the present invention. Specifically, the drift control unit 20 determines the target steering, target angle, and target speed of the steering wheel according to the drift degree of the vehicle, and generates corresponding steering control instructions. Thereby, precise and timely steering control is achieved during the vehicle drift process, thereby improving the stability during the vehicle drift process.
[0021] The drift control unit 20 can be implemented in a way that combines hardware or software or software and hardware.
[0022] The drift control unit 20 can be set in an electronic control unit (ECU) related to the chassis or power system of the vehicle V. For example, the drift control unit 20 can be set in the steering system ECU or the braking system ECU. In addition, the drift control unit 20 can also be set in the vehicle body controller (VCU) or the domain controller.
[0023] In one embodiment, the drift control unit 20 includes a memory and one or more processors. The memory contains executable instructions that, when executed by the one or more processors, cause the one or more processors to execute a drift control method according to an embodiment of the present invention.
[0024] The execution unit 30 is configured to perform a steering operation according to a steering control instruction from the drift control unit 20. The execution unit 30 may include a steering system controller. When the vehicle's steering system is a steer-by-wire system, the steering system controller sends the steering control instruction to a steering wheel force feedback simulator (steering wheel torque feedback simulator).
[0025] Figure 2 A drift control method 200 according to an embodiment of the present invention is shown. The method 200 may be executed by the above-mentioned drift control unit 20.
[0026] At block 202, the drift control unit 20 calculates the value of the drift amount and its rate of change in real time based on the vehicle drift state-related information from the sensor unit 10.
[0027] The value of the drift amount characterizes the degree of vehicle drift. In other words, the magnitude of the value of the drift amount reflects the degree of vehicle drift. The larger the value, the higher the degree of drift; the smaller the value, the lower the degree of drift.
[0028] Next, some embodiments for calculating the value of the drift amount are introduced. After obtaining the value of the drift amount, its rate of change can be obtained through differential calculation. For example, sample the values of the drift amount in a continuous time series; then use a differential algorithm to calculate the instantaneous rate of change; then use a low-pass filter to eliminate the influence of measurement noise.
[0029] In one embodiment, the drift amount is represented by a drift angle. The drift angle can be represented by the angle between the actual slip direction of the vehicle's rear wheels and the vehicle's traveling direction, or by the angle between the actual movement direction of the vehicle (the direction of the center-of-mass velocity vector) and the longitudinal axis of the vehicle body. The present invention does not limit the specific manner of obtaining the drift angle.
[0030] In some other embodiments, the drift amount can be calculated based on the vehicle's lateral motion parameters. One way is to calculate the drift amount according to a single lateral motion parameter. For example, determine the value of the drift amount based on the measurement result of the vehicle body lateral acceleration. Specifically, the value of the drift amount increases as the vehicle body lateral acceleration increases. Another way is to calculate the drift amount according to multiple lateral motion parameters and through a weighting algorithm. For example, determine the drift amount based on the vehicle body yaw angle and yaw angular velocity and through a weighting algorithm.
[0031] According to an embodiment of the present invention, the vehicle drift degree is pre-divided into four levels in ascending order of the vehicle drift degree, namely, the drifting start level (L0), the first drift level (L1), the second drift level (L2), and the danger level (L3) with gradually increasing drift degree. These four levels are preset based on the drift amount. Each drift level has a corresponding drift amount range, that is, the upper and lower limits of the drift amount. For example, if the currently measured drift amount of vehicle V is within the range of the first drift level (L1), it is determined that the current drift level of vehicle V is the first drift level. The drift amount ranges corresponding to each drift level are predetermined and can be adjusted according to different vehicle models, user requirements, and application scenarios.
[0032] It can be understood that when determining the current drift level of the vehicle, it can be determined according to the specific parameter value representing the drift amount. For example, in an embodiment where the drift angle is used to represent the drift amount, the current drift level is determined according to the value of the drift angle.
[0033] Next, an example of the above four drift levels is shown in Table 1. In this example, the drift angle is used to represent the drift amount, and each drift level corresponds to a preset drift angle range. In Table 1, the first column represents the drift angle range, and the second column represents the drift level.
[0034] Table 1
[0035] Drift angle range Drift level 0～a Initial drift level (L0) a to b First drift level (L1) b to c Second drift level (L2) >c Hazard level (L3)
[0036] In block 204, the drift control unit 20 calculates the value of the stability factor (SF: Stability Factor) based on the value of the drift amount and its change rate. The stability factor is used to evaluate the degree of out-of-control risk of the vehicle during drifting. Specifically, the value of the stability factor can be between 0 and 1. The larger the value, the more stable the vehicle dynamics and the lower the out-of-control risk level; the smaller the value, the more unstable the vehicle dynamics and the higher the out-of-control risk level.
[0037] Next, the specific implementation of block 204 is introduced.
[0038] In one implementation, in block 2041, the drift control unit 20 determines the first value (SF1) of the stability factor in a manner negatively correlated with the value of the drift amount. In one embodiment, the first value (SF1) of the stability factor is calculated using the following formulas (1) and (2):
[0039] SF1 = f(ψ) (1)
[0040]
[0041] In Equation (1), ψ represents the value of the drift amount. In Equation (2), it is defined that the first value of the stability factor monotonically decreases as the drift amount increases. According to an embodiment of the present invention, the monotonic decrease is not a linear decrease, but rather the greater the value of the drift amount, the greater (steeper) the decrease slope. In other words, |ΔSF1 / Δψ| increases as ψ increases, thereby reflecting an increasing risk sensitivity.
[0042] In some other embodiments, the negative correlation relationship between the first value of the stability factor and the value of the drift amount is preset. For example, such a negative correlation relationship is expressed by a curve, a look-up table, or a parametric model (such as an exponential decay model) preset and stored in the drift control unit 20. For clarity, a curve expressing such a negative correlation relationship is shown in Figure 3A where the horizontal axis represents the value of the drift amount (ψ) and the vertical axis represents the first value of the stability factor (SF1).
[0043] In block 2042, when the change rate of the value of the drift amount is greater than zero (i.e., in the case of increasing drift degree), the drift control unit 20 determines the second value (SF2) of the stability factor in a manner negatively correlated with the change rate of the value of the drift amount. In one embodiment, the second value (SF2) of the stability factor is calculated using the following Equations (3) and (4):
[0044] SF2 = f(rψ) (3)
[0045]
[0046] In Equation (3), rψ represents the change rate of the value of the drift amount. In Equation (4), it is defined that the second value of the stability factor monotonically decreases as the drift amount increases.
[0047] According to an embodiment of the present invention, the monotonic decrease is not a linear decrease, but rather the greater the value of the drift amount, the greater (steeper) the decrease slope. In other words, |ΔSF2 / Δrψ| increases as rψ increases, thereby reflecting an increasing risk sensitivity.
[0048] In some other embodiments, the negative correlation relationship between the second value of the stability factor and the change rate of the value of the drift amount is preset. For example, such a negative correlation relationship is expressed by a curve, a look-up table, or a parametric model (such as an exponential decay model) preset and stored in the drift control unit 20. For clarity, a curve expressing such a negative correlation relationship is shown in Figure 3B where the horizontal axis represents the change rate of the value of the drift amount (rψ) and the vertical axis represents the second value of the stability factor (SF2).
[0049] It should be understood that the specific manner of the negative correlation relationship in block 2042 may be different from that of the negative correlation relationship in block 2041. In other words, the second value of the stability factor is calculated independently of its first value. For example, they may adopt different functional forms, different curve styles, or different calibration processes.
[0050] When the rate of change of the value of the drift amount is less than or equal to zero (i.e., in the case where the degree of drift decreases or remains unchanged), the drift control unit 20 determines the second value (SF2) of the stability factor as a value indicating a low risk level of vehicle out-of-control, such as 1, and at this time, the risk of vehicle out-of-control is zero or almost zero.
[0051] In block 2043, the drift control unit 20 determines the value of the stability factor based on the first value and the second value of the stability factor.
[0052] In one embodiment, the drift control unit 20 determines the value (SF) of the stability factor according to the first value (SF1) and the second value (SF2) of the stability factor and by using a weighted average algorithm.
[0053] In one embodiment, the drift control unit 20 uses the following formula (5) to calculate the value of the stability factor:
[0054] SF = α * SF1 + β * SF2 (5)
[0055] Where, α is the weight coefficient of the first value of the stability factor and has an initial value α0; β is the weight coefficient of the second value of the stability factor and has an initial value β0. α and β respectively have a predetermined adjustment range, that is, α ∈ [α_min, α_max], β ∈ [β_min, β_max].
[0056] According to an embodiment of the present invention, the weight of the value of the drift amount is always greater than the weight of the rate of change of the value of the drift amount, that is, α > β. And the weights α and β are adjustable, for example, having the following adjustment strategy.
[0057] If the value of the drift amount (relatively large) is greater than the drift amount threshold, but its rate of change (almost no change) is less than the rate of change threshold, the weight of the second value of the stability factor will be reduced from the current value (for example, the initial value) to the minimum value of its predetermined adjustment range, and at this time, the calculated stability factor will be a very small value.
[0058] If the value of the drift amount (relatively small) is less than or equal to the drift amount threshold, but its rate of change (very fast) is greater than or equal to the rate of change threshold, at this time, the weight of the second value of the stability factor will be increased from its current value (for example, the initial value) to the maximum value of its predetermined adjustment range, and at this time, the calculated stability factor is a relatively large value.
[0059] Next, an example of the weight adjustment strategy is shown in Table 2.
[0060] Table 2
[0061] Operating condition characteristics Weight adjustment Output characteristics ψ > ψ_thr & rψ < rψ_thr β → β_min (Effect of decreasing change rate) <![CDATA[SF approaches SF1]]> ψ ≤ ψ_thr & rψ ≥ rψ_thr β → β_max (Effect of increasing change rate) <![CDATA[SF approaches SF2]]>
[0062] According to such a weight adjustment strategy, the value ψ of the drift amount is used as the main risk assessment index (α > β). When a rapid dynamic change (rψ suddenly increases) occurs, the decision-making weight of the change rate is automatically increased. The threshold ψ_thr can be pre-calibrated according to vehicle geometric parameters (such as the wheelbase / track width ratio). The threshold rψ_thr can be pre-calibrated based on critical instability test data.
[0063] In block 206, the drift control unit 20 determines the steering control strategy for drift assistance based on the value of the drift amount ψ and the value of the stability factor SF, and generates a steering control instruction corresponding to the determined steering control strategy. The steering control strategy includes three aspects: the target steering of the steering wheel, the target steering angle, and the target rotation speed. Accordingly, the steering control instruction includes the determined target steering, target steering angle, and target rotation speed of the steering wheel.
[0064] The target steering of the steering wheel is one of the following directions: 1) CounterSteer: The direction opposite to the current vehicle steering, see Figure 4 Situation ① in. This situation is called the first steering mode, and a stable yaw moment can be generated in the first steering mode. 2) SteerIn: The direction the same as the current vehicle steering, see Figure 4 Situation ② in. This situation is called the second steering mode. In the second steering mode, the controllable sideslip can be enhanced.
[0065] The target steering angle of the steering wheel refers to the angle by which the steering wheel turns from the current position (current angle) to the target position (target angle).
[0066] The target rotation speed of the steering wheel refers to the speed at which the target steering angle is completed, that is, the rotation speed from the current angle to the target angle.
[0067] Next, the specific implementation manner of block 206 is introduced.
[0068] In block 2061, the drift control unit 20 determines whether the calculated value of the drift amount is greater than the first drift degree threshold. The first drift degree threshold is the upper limit value of the starting drift level or the lower limit value of the first drift level, for example, the value a in Table 1.
[0069] If it is determined that the value of the drift amount is greater than the first drift degree threshold, then method 200 proceeds to block 2062.
[0070] In block 2062, the drift control unit 20 determines the target steering of the steering wheel as reverse steering, that is, in a direction opposite to the current vehicle steering, and enters the first steering mode.
[0071] In block 2063, the drift control unit 20 determines the target steering angle of the steering wheel in a manner positively correlated with the value of the drift amount (ψ). In other words, the target steering angle monotonically increases as the value of the drift amount increases. According to an embodiment of the present invention, the monotonically increasing is not a linear increase, but the greater the value of the drift amount, the greater the increase slope. This positive correlation relationship can be expressed by a curve, a look-up table, or a parametric model preset and stored in the drift control unit 20.
[0072] In an embodiment where the front wheels of the vehicle are steering wheels, the target front-wheel steering angle of the vehicle's front wheels is calculated based on the difference in the lateral forces acting on the front and rear wheels of the vehicle on the current driving road surface, so as to change the traveling direction of the vehicle's front wheels, thereby adjusting the front axle force arm (the Z-direction rotational force arm of the front axle) by changing the traveling direction of the front wheels, achieving the balance of the vehicle's yaw moment, and achieving the control purpose of balancing the vehicle's drift dynamics. In this embodiment, the target steering angle of the steering wheel is determined based on the target front-wheel steering angle and the transmission ratio k, and the transmission ratio can be dynamically adjusted according to the vehicle speed.
[0073] In an embodiment where all four wheels of the vehicle are steering wheels, the target front-wheel steering angle and the target rear-wheel steering angle of the vehicle are calculated based on the difference in the lateral forces acting on the front and rear wheels of the vehicle on the current driving road surface, so as to change the traveling directions of both the front wheels and the rear wheels, thereby achieving the coordinated adjustment of the front axle and rear axle force arms. For example, increasing the front axle force arm (the Z-direction rotational force arm of the front axle) and reducing the rear axle force arm (the Z-direction rotational force arm of the rear axle), or reducing the front axle force arm (the Z-direction rotational force arm of the front axle) and increasing the rear axle force arm (the Z-direction rotational force arm of the rear axle), achieving the balance of the vehicle's yaw moment, and achieving the control purpose of balancing the vehicle's drift dynamics. In this embodiment, the target steering angle of the steering wheel is determined based on the target front-wheel steering angle and the transmission ratio k, and the transmission ratio can be dynamically adjusted according to the vehicle speed. Additionally, an independent control command is generated based on the target rear-wheel steering angle and sent to the rear-wheel steering module.
[0074] In block 2064, the drift control unit 20 determines the target rotation speed (TR: target rate) of the steering wheel based on the target steering angle of the steering wheel and the value of the stability factor. The following describes the specific implementation of block 2064 (blocks 2065 to 2067).
[0075] In one implementation, in block 2065, the drift control unit 20 determines the first value (TR1) of the target rotation speed in a manner positively correlated with the target steering angle of the steering wheel. In one embodiment, the first value (TR1) of the target rotation speed is calculated using the following formulas (6) and (7):
[0076] TR1 = f(θ) (6)
[0077]
[0078] In Equation (6), θ represents the value of the target rotation angle. In Equation (7), it is defined that the first value of the target rotational speed increases monotonically as the target rotation angle increases. According to an embodiment of the present invention, the monotonic increase is not a linear increase, but rather the greater the value of the target rotation angle, the greater the increase slope. In other words, |ΔTR1 / Δθ| increases as θ increases.
[0079] In some other embodiments, the positive correlation relationship between the first value of the target rotational speed and the value of the target rotation angle is preset. For example, such a positive correlation relationship is expressed by a curve, a look-up table, or a parametric model that is preset and stored in the drift control unit 20. For clarity, a curve expressing such a positive correlation relationship is shown in Figure 5A where the horizontal axis represents the value of the target rotation angle (θ), and the vertical axis represents the first value of the target rotational speed (TR1).
[0080] At block 2066, the drift control unit 20 determines the second value (TR2) of the target rotational speed in a manner negatively correlated with the value of the stability factor. In one embodiment, the second value (TR2) of the target rotational speed is calculated using the following Equations (8) and (9):
[0081] TR2 = f(SF) (8)
[0082]
[0083] In Equation (8), SF represents the value of the stability factor. In Equation (9), it is defined that the second value of the target rotational speed decreases monotonically as the value of the stability factor increases. According to an embodiment of the present invention, the monotonic decrease is not a linear decrease, but rather the greater the value of the stability factor, the greater the decrease slope. In other words, |ΔTR2 / ΔSF| increases as SF increases.
[0084] In some other embodiments, the negative correlation relationship between the second value of the target rotational speed and the value of the stability factor is preset. For example, such a positive correlation relationship is expressed by a curve, a look-up table, or a parametric model that is preset and stored in the drift control unit 20. For clarity, a curve expressing such a negative correlation relationship is shown in Figure 5B where the horizontal axis represents the value of the stability factor (SF), and the vertical axis represents the second value of the target rotational speed (TR2).
[0085] At block 2067, the drift control unit 20 determines the value of the target rotational speed based on the first value (TR1) and the second value (TR2) of the target rotational speed and using a weighted average algorithm.
[0086] In one embodiment, the drift control unit 20 calculates the value of the target rotational speed using the following formula (10):
[0087] TR = γTR1 + δTR2 (5)
[0088] Where γ is the weight coefficient of the first value of the target rotational speed and has an initial value γ0; δ is the weight coefficient of the second value of the target rotational speed and has an initial value δ0; γ and δ each have a predetermined adjustment range, that is, γ ∈ [γ_min, γ_max], δ ∈ [δ_min, δ_max].
[0089] According to an embodiment of the present invention, the weight of the value of the stability factor is always greater than the weight of the value of the target steering angle, that is, δ > γ. And the weights γ and δ are adjustable, for example, having the following adjustment strategy.
[0090] If the value of the stability factor (lower) is less than the stability factor threshold, it means a high risk of out-of-control. At this time, the weight coefficient of the first value of the target rotational speed is increased from the current value (initial value) to the maximum value of its predetermined adjustment range. At this time, the calculated target rotational speed will also be a very large value.
[0091] If the target steering angle of the steering wheel (larger) is greater than the target steering angle threshold, and the value of the stability factor (larger) is greater than or equal to the stability factor threshold, at this time, the weight coefficient of the second value of the target rotational speed is increased from the current value (initial value) to the maximum value of its predetermined adjustment range. At this time, the calculated target rotational speed will also be a very small value.
[0092] Next, an example of the weight adjustment strategy is shown in Table 3.
[0093] Table 3
[0094] Operating condition characteristics Weight adjustment Output characteristics SF < SF_thr γ → β_max (Effect of increasing steering angle) <![CDATA[TR approaches TR1]]> θ > θ_thr & SF ≥ SF_thr δ → δ_max (Effect of increasing stability factor) <![CDATA[TR approaches TR2]]>
[0095] According to such a weight adjustment strategy, the value of the stability factor is the main risk assessment index. When a high risk of out-of-control occurs, the decision weight of the stability factor is automatically increased.
[0096] According to an embodiment of the present invention, when the value of the drift amount is less than the second drift degree threshold and changes towards the first drift degree threshold at a rate greater than a predetermined rate (that is, when changing from the first drift level to the starting drift level quickly), method 200 enters block 2068. The second drift degree threshold is the upper limit value of the first drift level or the lower limit value of the second drift level. For example, the value b in Table 1.
[0097] At block 2068, the drift control unit 20 monitors the value of the drift amount; once it monitors that the value of the drift amount decreases to be equal to the first drift degree threshold, it determines the target steering of the steering wheel to be the same direction as the current vehicle steering, and enters the second steering mode.
[0098] After entering the second steering mode, the drift control unit 20 determines the target steering angle of the steering wheel according to the value of the drift amount. Specifically, the smaller the value of the drift amount, the larger the angle by which the steering wheel rotates in the same direction as the vehicle steering.
[0099] According to an embodiment of the present invention, when the value of the drift amount is less than or equal to the first drift degree threshold, method 200 enters block 2069. At block 2069, the steering control for drift assistance is not executed. In other words, when the current drift level is the starting drift level, the above-described steering control method is not executed because the drift degree is low at this time and there is no need for the intervention of steering control.
[0100] In addition, according to an embodiment of the present invention, when detecting one of the following multiple driver operations, the drift control unit 20 generates a request signal for requesting the driver to take over the vehicle: 1) The direction in which the driver operates the steering wheel is opposite to the target steering of the determined steering wheel; 2) The direction in which the driver operates the steering wheel is the same as the target steering of the determined steering wheel, but the steering wheel rotation speed requested by the driver is greater than the target rotation speed of the determined steering wheel.
[0101] At block 208, the drift control unit 20 sends a steering control instruction including the determined target steering, target steering angle, and target rotation speed to the execution unit 30, so that the execution unit 30 performs vehicle steering control according to the steering control instruction.
[0102] According to an embodiment of the present invention, there is also provided a machine-readable storage medium that stores executable instructions, which when executed by one or more processors cause the one or more processors to execute the above-described drift control method.
[0103] According to an embodiment of the present invention, there is also provided a computer program product that includes instructions, which when executed by one or more processors cause the one or more processors to execute the above-described drift control method.
[0104] It can be understood that all the operations in the above-described processes and methods are merely exemplary, and the present invention is not limited to any operation in the method or the order of these operations, but should cover all other equivalent transformations under the same or similar concepts.
[0105] The drift control unit may include one or more processors. These processors may be implemented using electronic hardware, computer software, or any combination thereof. Whether the processors are implemented as hardware or software will depend upon the particular application and the overall design constraints imposed on the system. By way of example, the processors, any part of a processor, or any combination of processors given in the present invention may be implemented as a microprocessor, a microcontroller, a digital signal processor (DSP), a field programmable gate array (FPGA), a programmable logic device (PLD), a state machine, gate logic, discrete hardware circuits, and other suitable processing components configured to perform the various functions described in the present invention. The functions of the processors, any part of a processor, or any combination of processors given in the present invention may be implemented as software executed by a microprocessor, a microcontroller, a DSP, or other suitable platform.
[0106] Software can generally be regarded as representing instructions, instruction sets, code, code segments, program code, programs, subroutines, software modules, applications, software applications, software packages, routines, subroutines, objects, running threads, processes, functions, etc. Software may reside on a computer-readable medium. The computer-readable medium may include, for example, a memory, which may be, for example, a magnetic storage device (such as a hard disk, a floppy disk, a magnetic stripe), an optical disk, a smart card, a flash memory device, a random access memory (RAM), a read-only memory (ROM), a programmable ROM (PROM), an erasable PROM (EPROM), an electrically erasable PROM (EEPROM), a register, or a removable disk. Although the memory is shown as being separate from the processor in several aspects given in the present invention, the memory may also be located inside the processor (such as a cache or a register).
[0107] The foregoing description has been provided to enable any person skilled in the art to make and use the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein. All structural and functional equivalents to the elements of the various aspects of the present invention that are known or later become known to those skilled in the art will be expressly incorporated herein by reference and are intended to be covered by the claims.
Claims
1. A drift control method for a vehicle, comprising: Calculate the value of the drift amount representing the degree of vehicle drift and its change rate based on the relevant parameters of the vehicle motion state; Calculating a stability factor value based on the drift value and its change rate, wherein the stability factor represents the risk level of loss of control during vehicle drift; A steering control strategy for assisting vehicle drifting is determined based on the value of the stability factor and the value of the drift amount, wherein the steering control strategy includes: When the value of the drift amount is greater than a first drift degree threshold, determining a target steering direction of the steering wheel as a direction opposite to the current vehicle steering direction, and determining a target steering angle of the steering wheel based on the value of the drift amount; and The target rotation speed of the steering wheel is determined based on the target turning angle of the steering wheel and the value of the stability factor.
2. The drift control method according to claim 1, wherein: The values of the stability factor calculated based on the value of the drift and its rate of change include: determining a first value of the stability factor in a manner that is negatively correlated to a value of the drift amount; When the rate of change of the value of the drift amount is greater than zero, determining the second value of the stability factor in a manner negatively correlated with the rate of change of the value of the drift amount, and when the rate of change of the value of the drift amount is less than or equal to zero, determining the second value of the stability factor as a value indicating the lowest level of out-of-control; and The value of the stability factor is determined based on the first value and the second value of the stability factor and using a weighted average algorithm.
3. The drift control method according to claim 2, wherein: The first value of the stability factor decreases monotonically as the value of the drift increases, and the greater the value of the drift, the greater the decrease slope; as well as When the change rate of the drift value is greater than zero, the second value of the stability factor decreases monotonically as the change rate of the drift value increases, and the greater the change rate of the drift value, the greater the decrease slope.
4. The drift control method according to claim 2 or 3, wherein: The weight coefficient of the first value of the stability factor is greater than the weight coefficient of the second value of the stability factor.
5. The drift control method according to claim 1, wherein: Determining the target steering angle of the steering wheel based on the value of the drift amount includes: determining the target steering angle of the steering wheel in a manner that is positively correlated with the value of the drift amount, The target turning angle increases monotonically with the increase of the drift value, and the larger the drift value is, the greater the increase slope is.
6. The drift control method according to claim 5, wherein: When the steering wheels of the vehicle are the front wheels, the front wheel target angle corresponding to the target steering angle of the steering wheel is determined based on the difference in lateral force between the front and rear wheels, so as to adjust the front axle arm of the vehicle by adjusting the travel direction of the front wheels, thereby achieving the yaw moment balance of the vehicle.
7. The drift control method according to claim 5, wherein: When the steering wheels of the vehicle are the front wheels and the rear wheels, the front wheel target turning angle and the rear wheel target turning angle corresponding to the target turning angle of the steering wheel are determined based on the difference in lateral force between the front and rear wheels, so as to coordinately adjust the front axle and rear axle force arms of the vehicle by adjusting the travel direction of the front and rear wheels, thereby achieving the yaw moment balance of the vehicle.
8. The drift control method according to claim 1, wherein: Determining the target speed based on the target steering wheel angle and the stability factor value includes: determining a first value of the target rotation speed in a manner that is positively correlated with the target rotation angle; determining a second value of the target rotation speed in a manner inversely correlated with a value of the stability factor; and The value of the target speed is determined based on the first value and the second value of the target speed and using a weighted average algorithm.
9. The drift control method according to claim 8, wherein: The first value of the target speed increases monotonically as the target speed increases, and the increase slope increases as the target speed increases; and The second value of the target rotation speed decreases monotonically as the value of the stability factor increases, and the greater the value of the stability factor is, the greater the decrease slope is.
10. The drift control method according to claim 8 or 9, wherein: The weighting coefficient of the first value of the target rotation speed is smaller than the weighting coefficient of the second value of the target rotation speed.
11. The drift control method according to claim 1, wherein: The steering control strategy also includes: When the value of the drift amount is less than or equal to the first drift degree threshold, the steering control for drift assistance is not performed.
12. The drift control method according to claim 1, further comprising: Determining a current drift level of the vehicle based on the value of the drift amount, wherein the current drift level is one of a plurality of predetermined drift levels, the plurality of predetermined drift levels comprising, in order of increasing drift degrees: a starting drift level, a first drift level, a second drift level, and a danger level; Each drift level has a predetermined drift range, and the first drift level threshold is an upper limit value of the drift range of the drift level or a lower limit value of the drift range of the first drift level.
13. The drift control method according to claim 12, wherein: The steering control strategy also includes: monitoring a change in the value of the drift amount when the value of the drift amount is less than the second drift degree threshold and decreases toward the first drift degree threshold at a rate greater than a predetermined rate; and Once the value of the monitored drift amount is reduced to be equal to the first drift degree threshold, determining the target steering direction of the steering wheel to be the same direction as the current vehicle steering direction; The second drift level threshold is an upper limit value of the drift amount range of the first drift level or a lower limit value of the drift amount range of the second drift level.
14. The drift control method according to claim 1, further comprising: Generates a reminder message to remind the driver to take over the vehicle when one of the following driver actions is detected: - The driver's steering wheel is in the opposite direction to the target steering direction of the decision-making steering wheel; - The direction in which the driver operates the steering wheel is the same as the determined target steering direction of the steering wheel, but the direction speed requested by the driver is greater than the determined target steering speed of the steering wheel.
15. A drift control unit for a vehicle, comprising a memory and one or more processors, wherein the memory stores executable instructions, and when the instructions are executed by the one or more processors, the drift control method according to any one of claims 1 to 14 is executed. 16 . A machine-readable storage medium storing executable instructions, which, when executed by one or more processors, cause the one or more processors to perform the drift control method according to any one of claims 1 to 14.
17. A computer program product comprising instructions, which, when executed by one or more processors, cause the one or more processors to perform the drift control method according to any one of claims 1 to 14.