A longitudinal instantaneous slip ratio estimation method based on adaptive filtering

Abstract

The application discloses a longitudinal instantaneous slip rate estimation method based on adaptive filtering, which comprises the following steps: 1, acquiring the vehicle driving state, four-wheel wheel speed original signals, vehicle longitudinal acceleration signals, four-wheel driving / braking torque signals and four-wheel tire pressure signals; 2, estimating the vehicle speed, four-wheel tire longitudinal slip stiffness and four-wheel tire body longitudinal stiffness values; 3, calculating four-wheel filter coefficients and cut-off frequencies and selecting filter types and filter coefficients in combination with the inherent frequency characteristics of vehicle system vibration; and 4, filtering the four-wheel original longitudinal slip rate to obtain four-wheel longitudinal instantaneous slip rate estimation values. The application considers the influence of tire dynamic deformation on wheel longitudinal slip rate estimation, can improve the wheel longitudinal slip rate estimation precision and further improve the control precision of the wheel slip control system, and has the advantages of simple realization, good robust performance and the like.

Description

Technical Field

[0001] This invention relates to the field of vehicle dynamics control, and in particular to the field of wheel slippage dynamics control for distributed drive electric vehicles. Background Technology

[0002] The accuracy of wheel slip ratio estimation determines the effectiveness, stability, and control precision of the ABS / TCS algorithm. Existing wheel slip ratio estimation methods rely on low-pass filtering of wheel speed signals (cutoff frequency typically 10-20Hz) and calculations based on the vehicle speed signal estimated from the wheel speed signals. Low-pass filtering of the wheel speed signals aims to suppress interference from vehicle, suspension, drive / brake actuator systems, and wheel vibrations, but inevitably limits the bandwidth frequency of the closed-loop control system. This was acceptable given the low control input bandwidth frequency and large system signal transmission delay of traditional brake / drive actuators. Correspondingly, rule-based discrete wheel slip control is typically used in control algorithm design, and extensive experimental calibration is conducted to compensate for the impact of system hysteresis and time delay on its robustness. However, with the development of distributed drive and drive-by-wire chassis technologies, the complexity and disturbance uncertainty of the control system have been significantly reduced at multiple levels, including signal acquisition, signal transmission, and actuator performance. On the one hand, both drive-by-wire and brake-by-wire systems typically use electric motors as actuators, which offer advantages such as precise torque control, large response bandwidth, and easy implementation of accurate feedback. This makes it possible to design ABS / TCS algorithms based on models for large-scale industrial applications. On the other hand, distributed drive and drive-by-wire chassis vehicles greatly simplify the drive / braking system transmission mechanism, significantly reducing transmission time delay and dynamic hysteresis. This also significantly reduces the interference of transmission system vibration on wheel speed signal measurement. Consequently, the hysteresis effect caused by tire dynamic deformation and the impact of vibration on wheel speed signal measurement become increasingly prominent. From the perspective of further improving system performance, the low-pass filtering with a low cutoff frequency used for wheel speed measurement signals cannot reflect the transient response characteristics of tire force caused by tire dynamic deformation in the estimated slip ratio signal. Summary of the Invention

[0003] This invention considers the significant impact of tire dynamic deformation on the estimation of wheel instantaneous slip ratio, and proposes a longitudinal instantaneous slip ratio estimation method based on adaptive filtering. The aim is to achieve a more accurate estimation of the longitudinal instantaneous slip ratio, fully utilize the potential of the braking / drive system actuators, thereby improving the bandwidth frequency of the closed-loop control system, and ultimately achieving more efficient use of road adhesion to improve vehicle driving safety.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention includes the following steps:

[0005] The present invention provides a longitudinal instantaneous slip rate estimation method based on adaptive filtering, characterized by the following steps:

[0006] Step 1: If the vehicle's driving state at time k is without steering action and is in a driving or braking state, then proceed to step 2; otherwise, assign k+1 to k; return to step 1.

[0007] Step 2: Obtain the raw signals of the four wheel speeds at time k. in, This represents the original wheel speed signal for the i-th round at time k. (This refers to the original wheel speed signals for all four wheels.) Perform low-pass filtering to obtain the filtered wheel speed signal. in, This represents the filtered wheel speed signal at time k in the i-th round;

[0008] Will Subtract the filtered wheel speed signal at time k-1 in the i-th round Then divide by the sampling time T c Thus, the time derivative signal of the wheel speed in the i-th round at time k is obtained.

[0009] Step 3: Obtain the longitudinal acceleration signal of the vehicle at the current time k. And combined with the filtered wheel speed signal Estimate the vehicle speed at time k.

[0010] Step 4: Calculate the nominal wheel slip ratio of the i-th round at time k.

[0011] If the vehicle is driving under driving conditions at time k, then calculate the nominal wheel slip ratio of the i-th wheel at time k. Where, r e Effective rolling radius;

[0012] If the vehicle is braking at time k, then calculate the nominal wheel slip ratio signal of the i-th wheel at time k.

[0013] Step 5: Calculate the derivative signal of the nominal wheel slip ratio of the i-th wheel at time k.

[0014] If the vehicle is driving under driving conditions at time k, then calculate the derivative signal of the nominal wheel slip ratio of the i-th wheel at time k.

[0015] If the vehicle is braking at time k, then calculate the derivative of the nominal wheel slip ratio of the i-th wheel at time k.

[0016] Step 6: Obtain the torque value applied to the rim of the i-th wheel at time k. Calculate the longitudinal tire force of the i-th wheel at time k.

[0017] If the vehicle is in driving condition at time k, then calculate the longitudinal tire force of the i-th wheel at time k. Where J is the moment of inertia of the wheel;

[0018] If the vehicle is braking at time k, then calculate the longitudinal tire force of the i-th wheel at time k.

[0019] Will Subtract the longitudinal tire force signal of the i-th wheel at time k-1 Then divide by the sampling time T c Thus, the derivative signal of the longitudinal tire force of the i-th wheel at time k is obtained.

[0020] Step 7: Calculate the longitudinal slip stiffness of the i-th tire at time k.

[0021] Step 8: Obtain the tire pressure signal of the i-th wheel at time k. and combined Estimate the longitudinal stiffness of the i-th tire body at time k.

[0022] Step 9: Calculate the filtering coefficient τ of the i-th round at time k. i,k :

[0023] If the vehicle is driving under driving conditions at time k, the filter coefficients for the i-th round at time k are...

[0024] If the vehicle is braking at time k, the filter coefficients for the i-th round at time k are...

[0025] Calculate the cutoff frequency of the i-th round at time k.

[0026] Step 10, according to Based on the inherent frequency characteristics of vehicle vibration, select the filter type and filter coefficients, and determine the original slip ratio value of the i-th wheel at the current time k. Perform filtering:

[0027] If the vehicle is driving under driving conditions at time k, the initial slip ratio of the i-th wheel at time k is...

[0028] If the vehicle is braking at time k, the original slip ratio signal of the i-th wheel at time k...

[0029] When the cutoff frequency The cutoff frequency f greater than the upper limit of the i-th round i,ch At that time, a digital bandpass filter was used for... Filtering is performed to obtain the instantaneous slip ratio of the i-th wheel at time k+1. Among them, f i,ch The natural vibration frequency f of the torsional vibration of the i-th tire is greater than that of the i-th tire. i,tt ;

[0030] When the cutoff frequency Less than the critical cutoff frequency f of the i-th round i,cc At that time, a first-order digital low-pass filter was used for... Filtering is performed to obtain the instantaneous slip ratio of the i-th wheel at time k+1. Among them, f i,cc The natural vibration frequency f of the i-th tire torsional vibration is less than that of the i-th tire. i,tt ;

[0031] When the cutoff frequency The frequency f is less than the lower cutoff frequency of the i-th round. i,cl At that time, a first-order digital low-pass filter was used for... Filtering is performed to obtain the instantaneous slip ratio of the i-th wheel at time k+1. The cutoff frequency of the first-order digital low-pass filter is f. i,cl .

[0032] The longitudinal instantaneous slip ratio estimation method based on adaptive filtering described in this invention is also characterized in that, in step 8, the longitudinal stiffness C of the i-th tire body is calibrated experimentally and stored in the form of a map. i,Fx With the tire pressure signal p of the i-th round i and vehicle speed signal v x The relationship between them.

[0033] The passband range of the bandpass digital filter in step 10 is: in, Let represent the lower passband limit of the bandpass digital filter in the i-th round, and The natural frequency f of the vertical vibration of the unsprung mass in the i-th round is greater than the frequency f of the unsprung mass in the i-th round. i,uv and the natural frequency f of the longitudinal vibration of the sprung mass sl ; Let represent the upper passband limit of the bandpass digital filter in the i-th round, and The natural frequency f of the torsional vibration of the i-th tire is greater than that of the i-th tire. i,ttAnd less than the natural frequency f of the longitudinal vibration of the i-th tire. i,tl and the natural frequency f of vertical vibration i,tv .

[0034] Let the cutoff frequency of the first-order digital low-pass filter in the i-th round be f. i,c Then calculate the instantaneous slip ratio of the i-th wheel at time k+1.

[0035] The present invention provides an electronic device, including a memory and a processor, characterized in that the memory is used to store a program that supports the processor in executing the longitudinal instantaneous slip ratio estimation method, and the processor is configured to execute the program stored in the memory.

[0036] The present invention discloses a computer-readable storage medium on which a computer program is stored, wherein the computer program, when executed by a processor, performs the steps of the longitudinal instantaneous slip ratio estimation method.

[0037] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0038] 1. This invention proposes a longitudinal instantaneous slip ratio estimation method based on adaptive filtering. The instantaneous slip ratio, considering the influence of tire dynamic hysteresis, is used as a state variable to completely characterize the tire's transient force response. An adaptive filter with adjustable filter type and coefficients is designed based on the tire transient characteristic equation described by the longitudinal instantaneous slip ratio as the state variable, combined with the vehicle's natural vibration frequency characteristics. By adaptively filtering the raw longitudinal slip ratio signal obtained from measurement and calculation, accurate estimation of the longitudinal instantaneous slip ratio is achieved. Furthermore, by estimating the instantaneous slip ratio, a more accurate tire force response characteristic is obtained, thereby fully utilizing the potential of the braking / drive system actuators, improving the bandwidth frequency of the closed-loop control system, and ultimately achieving more efficient use of road adhesion.

[0039] 2. This invention derives a clear expression for the relationship between the measurable original slip ratio and the longitudinal instantaneous slip ratio through theoretical analysis and derivation. It also has the technical feature of accurately and quantitatively describing the relationship between the longitudinal instantaneous slip ratio, the original wheel slip ratio, and the system parameter dependence. This provides a design principle for the implementation of adaptive filtering algorithms, reduces the blindness in algorithm design and parameter calibration, and thus saves development time.

[0040] 3. This invention uses an adaptive filtering method to estimate the longitudinal instantaneous slip rate. The adjustment of the filtering coefficient can be determined by combining offline calibration and online estimation. It has the technical characteristics of simple structure and easy implementation. It does not require obtaining accurate observation values ​​of parameters and state variables, and overcomes the problems of difficult real-time performance and poor observation accuracy of complex state observation algorithms, thus improving the stability of the algorithm.

[0041] 4. In the design phase, this invention can fully consider the impact of low-frequency interference signals from the vehicle body and suspension, as well as high-frequency disturbance signals from the road surface, on the longitudinal instantaneous slip ratio estimation of the adaptive filtering algorithm by calibrating the filter coefficients, thereby improving the robustness of the method.

[0042] 5. Regarding the variation of the filter coefficient with vehicle speed, wheel speed, tire longitudinal slip stiffness, and tire body longitudinal stiffness, this invention utilizes the sensor signals standard in automobiles to achieve online estimation of slip stiffness and longitudinal stiffness, without the need for additional sensors, making the solution easy to implement. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the control system involved in the present invention;

[0044] Figure 2 This is a flowchart of the method of the present invention;

[0045] Figure 3 This is a wheel model diagram considering the torsional deformation of the tire body for the present invention. Detailed Implementation

[0046] The invention will be further described below with reference to the accompanying drawings.

[0047] In this embodiment, in order to consider the impact of the hysteresis effect caused by tire dynamic deformation on the wheel slip ratio estimation, a longitudinal instantaneous slip ratio estimation method based on adaptive filtering is proposed. This method is based on the tire transient characteristic equation described by the longitudinal instantaneous slip ratio as a state variable and combined with the vibration natural frequency characteristics of the vehicle system. It is an adaptive filter with adjustable filter type and filter coefficient. By adaptively filtering the original longitudinal slip ratio signal obtained by measurement and calculation, the accurate estimation of the longitudinal instantaneous slip ratio can be achieved.

[0048] This invention relates to wheel speed sensors, tire pressure sensors, electronic stability control systems (ESC) (including ABS / TCS functions), vehicle control units (VCU), CAN bus, drive motor controllers (MCU), brake motor controllers (ECU), and wheel torsional vibration systems. Among these, the control systems involved include... Figure 1As shown, the designed longitudinal instantaneous slip ratio estimation algorithm is integrated into the Electronic Stability Control (ESC) system. The vehicle control unit (VCU) sends vehicle driving status information and its longitudinal acceleration signal to the ESC via the CAN bus. The raw wheel speed signals of the four wheels are measured by wheel speed sensors and sent to the ESC for signal processing. Tire pressure signals are measured by tire pressure sensors and sent to the ESC. Braking / drive torque is sent to the ESC via the CAN bus by the drive motor controller (MCU) or the brake system motor control ECU. Specifically, as... Figure 2 As shown, the method includes the following steps:

[0049] Step 1: If the vehicle's driving state at time k is without steering action and is in a driving or braking state, then proceed to step 2; otherwise, assign k+1 to k; return to step 1.

[0050] Step 2: Obtain the raw signals of the four wheel speeds at time k. in, This represents the original wheel speed signal for the i-th round at time k. (This refers to the original wheel speed signals for all four wheels.) Low-pass filtering is performed (the cutoff frequency of a low-pass filter is typically 10-20Hz, depending on the test calibration of the vehicle system) to obtain the filtered wheel speed signal. in, This represents the filtered wheel speed signal at time k in the i-th round;

[0051] Will Subtract the filtered wheel speed signal at time k-1 in the i-th round Then divide by the sampling time T c Thus, the time derivative signal of the wheel speed in the i-th round at time k is obtained.

[0052] Step 3: Obtain the longitudinal acceleration signal of the vehicle at the current time k. and combined Estimate the vehicle speed at time k.

[0053] Step 4: Calculate the nominal wheel slip ratio of the i-th wheel at time k.

[0054] If the vehicle is driving under driving conditions at time k, then calculate the nominal wheel slip ratio of the i-th wheel at time k. Where, r e Effective rolling radius;

[0055] If the vehicle is braking at time k, then calculate the nominal wheel slip ratio signal of the i-th wheel at time k.

[0056] Step 5: Calculate the time derivative signal of the nominal wheel slip ratio value of the i-th round at time k.

[0057] If the vehicle is in driving condition at time k, then calculate the derivative signal of the nominal wheel slip ratio of the i-th wheel at time k.

[0058] If the vehicle is braking at time k, then calculate the derivative of the nominal wheel slip ratio of the i-th wheel at time k.

[0059] Step 6: Obtain the torque value applied to the rim of the i-th wheel at time k. Calculate the longitudinal tire force of the i-th wheel at time k.

[0060] If the vehicle is in driving condition at time k, then calculate the longitudinal tire force of the i-th wheel at time k. Where J is the moment of inertia of the wheel;

[0061] If the vehicle is braking at time k, then calculate the longitudinal tire force of the i-th wheel at time k.

[0062] Will Subtract the longitudinal tire force signal of the i-th wheel at time k-1 Then divide by the sampling time T c Thus, the derivative signal of the longitudinal tire force of the i-th wheel at time k is obtained.

[0063] Step 7: Calculate the longitudinal slip stiffness of the i-th tire at time k.

[0064] Step 8: Obtain the tire pressure signal of the i-th wheel at time k. and combined Estimate the longitudinal stiffness of the i-th tire body at time k. The longitudinal stiffness C of the i-th tire body is calibrated in advance through experiments and stored in the form of a map. i,Fx With the tire pressure signal p of the i-th round i and vehicle speed signal v x The relationship between them.

[0065] Step 9: Calculate the filtering coefficient τ of the i-th round at time k. i,k :

[0066] If the vehicle is driving under driving conditions at time k, the filter coefficients for the i-th round at time k are...

[0067] If the vehicle is braking at time k, the filter coefficients for the i-th round at time k are...

[0068] Calculate the cutoff frequency of the i-th round at time k.

[0069] In this embodiment, the filter coefficient τ at any time in the i-th round i The calculation formula is based on the following:

[0070] For the wheel system of the i-th round, see attached... Figure 3 As shown, due to the elastic properties of the tire carcass, the tire can be simplified into a rigid ring connected to the rim via a torsion spring and damping element. Under the action of a driving torque, the elasticity of the tire causes the rim of the i-th wheel to rotate by an angle θ at any given time. i,r (t) and the rotation angle θ of the tire rigid ring i,b (t) are not equal. The longitudinal tire force F at any time in the i-th round is not equal. i,x (t) directly depends on the relative sliding speed between the tire rigid ring and the road surface at any time in the i-th round. Instead of the relative sliding speed between the wheel rim and the road surface at any time in the i-th round. The wheel speed signal of the i-th wheel at any given moment is measured by the wheel speed sensor installed on the rim of the i-th wheel. It is not the rigid ring rolling speed signal at any time in the i-th round. Therefore, the relative sliding speed v at any moment in the i-th round is estimated. i,sx (t) cannot directly reflect the longitudinal tire force F at any time in the i-th round. i,x (t) Characteristics. For any moment in the i-th round, the longitudinal tire force F i,x (t) In terms of control, the slip ratio at any time of the i-th wheel is usually used as the longitudinal tire force F at any time of the i-th wheel. i,x The state variable is (t), and the slip ratio at any time in the i-th wheel is related to the relative sliding speed at any time in the i-th wheel. To further illustrate the influence of tire dynamic deformation at any time in the i-th wheel on the longitudinal slip ratio, we first define the original wheel slip ratio s at any time in the i-th wheel. i,o (t):

[0071]

[0072] The wheel slip ratio can be directly calculated from the wheel speed signal measured by the wheel speed sensor and the estimated vehicle speed signal. However, it does not directly reflect the relationship with the longitudinal tire force. Therefore, it is necessary to further define the instantaneous wheel slip ratio s of the i-th wheel at any time that can directly reflect the relationship with the longitudinal tire force. i,r (t):

[0073]

[0074] longitudinal deformation rate of the tire body at any time in the i-th round The linear velocity of the wheel rim at any moment of the i-th wheel can be used as a basis. The linear velocity of the rigid ring rotation of the tire at any time in the i-th round Poor description:

[0075]

[0076] According to equations (1)-(3), the deformation rate described by the wheel slip ratio at any time of the i-th wheel can be obtained.

[0077]

[0078] Generally speaking, the torsional damping of the tire carcass is very small, and the dynamic tire force is mainly contributed by the deformation of the tire carcass. Therefore, for the transient tire force F at any time of the i-th wheel... i,x (t) can be obtained by the tire deformation u at any time in the i-th round. i (t) Description:

[0079] F i,x (t)=C i,Fx u i (t) (5)

[0080] Let C be the torsional stiffness of the tire body at any time in the i-th round. i,θ Then the longitudinal stiffness of the tire body at any time in the i-th round is

[0081] For the transient tire force F at any moment of the i-th round i,x (t) can also be obtained from the instantaneous wheel slip ratio s at any time in the i-th round. i,r (t) is used to describe:

[0082] F i,x (t)=F i,x [s i,r (t)] (6)

[0083] Taking the first derivative of equations (5) and (6) with respect to time, we can obtain:

[0084]

[0085] Substituting equation (4) into equation (7) and rearranging, we can obtain the instantaneous wheel slip ratio s at any time in the i-th round. i,r (t) represents the state variable, where s is the initial wheel slip ratio at any time in the i-th round. i,o (t) represents the tire transient characteristic equation input to the system:

[0086]

[0087] According to equation (8), the instantaneous wheel slip ratio s directly reflects the transient characteristics of the tire force of the i-th wheel. i,r (t) can be considered as the original wheel slip ratio s after the i-th round. i,o (t) is obtained by first-order low-pass filtering, and the filter coefficient τ is obtained at any time in the i-th round. i for Further observation reveals τ i With the longitudinal slip stiffness C of the tire i,s Longitudinal tire stiffness C i,Fx And vehicle speed v x (t) changes, so when designing a filter, it is necessary to estimate the above parameters to obtain the real-time filter coefficients and thus accurately estimate the instantaneous wheel slip rate.

[0088] The same logic applies to driving conditions:

[0089]

[0090] Step 10, according to Based on the inherent frequency characteristics of vehicle vibration, select the filter type and filter coefficients, and determine the original slip ratio value of the i-th wheel at the current time k. Perform filtering:

[0091] If the vehicle is driving under driving conditions at time k, the initial slip ratio of the i-th wheel at time k is...

[0092] If the vehicle is braking at time k, the original slip ratio signal of the i-th wheel at time k...

[0093] When the cutoff frequency The cutoff frequency f greater than the upper limit of the i-th round i,ch At that time, a digital bandpass filter was used for... Filtering is performed to obtain the instantaneous slip ratio of the i-th wheel at time k+1. Among them, f i,ch The natural vibration frequency f of the torsional vibration of the i-th tire is greater than that of the i-th tire. i,tt (f i,tt (Generally 30-50Hz); the passband range with digital pass filter is... in, Let represent the lower passband limit of the bandpass digital filter in the i-th round, and The natural frequency f of the vertical vibration of the unsprung mass in the i-th round is greater than the frequency f of the unsprung mass in the i-th round. i,uv (f i,uv Generally 10-15Hz (obtained through experimental calibration) and the longitudinal vibration natural frequency f of the sprung mass. sl (f sl Generally 10-15Hz, obtained through experimental calibration); Let represent the upper passband limit of the bandpass digital filter in the i-th round, and The natural frequency f of the torsional vibration of the i-th tire is greater than that of the i-th tire. i,tt And less than the natural frequency f of the longitudinal vibration of the i-th tire. i,tl (f i,tl (Generally 50-100Hz, obtained through experimental calibration) and the natural frequency f of vertical vibration. i,tv (f i,tv (Generally 50-100Hz, obtained through experimental calibration);

[0094] When the cutoff frequency Less than the critical cutoff frequency f of the i-th round i,cc At that time, a first-order digital low-pass filter was used for... Filtering is performed to obtain the instantaneous slip ratio of the i-th wheel at time k+1. Among them, f i,cc The natural vibration frequency f of the i-th tire torsional vibration is less than that of the i-th tire. i,tt Let the cutoff frequency of the first-order digital low-pass filter in the i-th round be f. i,c Then calculate the instantaneous slip ratio of the i-th wheel at time k+1.

[0095] In this embodiment, the instantaneous slip rate of the i-th wheel at time k+1 is... The calculation formula is a time discretization of formulas (8) and (9) into a computer-runnable expression.

[0096] When the cutoff frequency The frequency f is less than the lower cutoff frequency of the i-th round. i,cl (f i,cl When the frequency is typically 0-5Hz (obtained through experimental calibration), a first-order digital low-pass filter is used. Filtering is performed to obtain the instantaneous slip ratio of the i-th wheel at time k+1. The cutoff frequency of the first-order digital low-pass filter is f. i,cl .

[0097] In this embodiment, an electronic device includes a memory and a processor. The memory stores a program that supports the processor in executing the methods described above, and the processor is configured to execute the program stored in the memory.

[0098] In this embodiment, a computer-readable storage medium stores a computer program, which is executed by a processor to perform the steps of the above method.

Claims

1. A method for estimating longitudinal instantaneous slip rate based on adaptive filtering, characterized in that, Includes the following steps: Step 1: If the vehicle's driving state at time k is without steering action and is in a driving or braking state, then proceed to step 2; otherwise, assign k+1 to k. Return to step 1; Step 2: Obtain the raw signals of the four wheel speeds at time k. in, This represents the original wheel speed signal for the i-th round at time k. (This refers to the original wheel speed signals for all four wheels.) Perform low-pass filtering to obtain the filtered wheel speed signal. in, This represents the filtered wheel speed signal at time k in the i-th round; Will Subtract the filtered wheel speed signal at time k-1 in the i-th round Then divide by the sampling time T c Thus, the time derivative signal of the wheel speed in the i-th round at time k is obtained. Step 3: Obtain the longitudinal acceleration signal of the vehicle at the current time k. And combined with the filtered wheel speed signal Estimate the vehicle speed at time k. Step 4: Calculate the nominal wheel slip ratio of the i-th round at time k. If the vehicle is driving under driving conditions at time k, then calculate the nominal wheel slip ratio of the i-th wheel at time k. Where, r e Effective rolling radius; If the vehicle is braking at time k, then calculate the nominal wheel slip ratio signal of the i-th wheel at time k. Step 5: Calculate the derivative signal of the nominal wheel slip ratio of the i-th wheel at time k. If the vehicle is driving under driving conditions at time k, then calculate the derivative signal of the nominal wheel slip ratio of the i-th wheel at time k. If the vehicle is braking at time k, then calculate the derivative of the nominal wheel slip ratio of the i-th wheel at time k. Step 6: Obtain the torque value applied to the rim of the i-th wheel at time k. Calculate the longitudinal tire force of the i-th wheel at time k. If the vehicle is in driving condition at time k, then calculate the longitudinal tire force of the i-th wheel at time k. Where J is the moment of inertia of the wheel; If the vehicle is braking at time k, then calculate the longitudinal tire force of the i-th wheel at time k. Will Subtract the longitudinal tire force signal of the i-th wheel at time k-1 Then divide by the sampling time T c Thus, the derivative signal of the longitudinal tire force of the i-th wheel at time k is obtained. Step 7: Calculate the longitudinal slip stiffness of the i-th tire at time k. Step 8: Obtain the tire pressure signal of the i-th wheel at time k. and combined Estimate the longitudinal stiffness of the i-th tire body at time k. Step 9: Calculate the filtering coefficient τ of the i-th round at time k. i,k : If the vehicle is driving under driving conditions at time k, the filter coefficients for the i-th round at time k are... If the vehicle is braking at time k, the filter coefficients for the i-th round at time k are... Calculate the cutoff frequency of the i-th round at time k. Step 10, according to Based on the inherent frequency characteristics of vehicle vibration, select the filter type and filter coefficients, and determine the original slip ratio value of the i-th wheel at the current time k. Perform filtering: If the vehicle is driving under driving conditions at time k, the initial slip ratio of the i-th wheel at time k is... If the vehicle is braking at time k, the original slip ratio signal of the i-th wheel at time k... When the cutoff frequency The cutoff frequency f greater than the upper limit of the i-th round i,ch At that time, a digital bandpass filter was used for... Filtering is performed to obtain the instantaneous slip ratio of the i-th wheel at time k+1. Among them, f i,ch The natural vibration frequency f of the torsional vibration of the i-th tire is greater than that of the i-th tire. i,tt ; When the cutoff frequency Less than the critical cutoff frequency f of the i-th round i,cc At that time, a first-order digital low-pass filter was used for... Filtering is performed to obtain the instantaneous slip ratio of the i-th wheel at time k+1. Among them, f i,cc The natural vibration frequency f of the i-th tire torsional vibration is less than that of the i-th tire. i,tt ; When the cutoff frequency The frequency f is less than the lower cutoff frequency of the i-th round. i,cl At that time, a first-order digital low-pass filter was used for... Filtering is performed to obtain the instantaneous slip ratio of the i-th wheel at time k+1. The cutoff frequency of the first-order digital low-pass filter is f. i,cl .

2. The longitudinal instantaneous slip rate estimation method based on adaptive filtering according to claim 1, characterized in that, In step 8, the longitudinal stiffness C of the i-th tire body is calibrated through experiments and stored in the form of a map. i,Fx With the tire pressure signal p of the i-th round i and vehicle speed signal v x The relationship between them.

3. The longitudinal instantaneous slip rate estimation method based on adaptive filtering according to claim 1, characterized in that, The passband range of the bandpass digital filter in step 10 is: in, Let represent the lower passband limit of the bandpass digital filter in the i-th round, and The natural frequency f of the vertical vibration of the unsprung mass in the i-th round is greater than the frequency f of the unsprung mass in the i-th round. i,uv and the natural frequency f of the longitudinal vibration of the sprung mass sl ; Let represent the upper passband limit of the bandpass digital filter in the i-th round, and The natural frequency f of the torsional vibration of the i-th tire is greater than that of the i-th tire. i,tt And less than the natural frequency f of the longitudinal vibration of the i-th tire. i,tl and the natural frequency f of vertical vibration i,tv .

4. The longitudinal instantaneous slip rate estimation method based on adaptive filtering according to claim 1, characterized in that, Let the cutoff frequency of the first-order digital low-pass filter in the i-th round be f. i,c Then calculate the instantaneous slip ratio of the i-th wheel at time k+1.

5. An electronic device, comprising a memory and a processor, characterized in that, The memory is used to store a program that supports the processor in executing any of the longitudinal instantaneous slip ratio estimation methods of claims 1-4, the processor being configured to execute the program stored in the memory.

6. A computer-readable storage medium storing a computer program thereon, characterized in that, When the computer program is run by the processor, it performs the steps of the longitudinal instantaneous slip ratio estimation method according to any one of claims 1-4.

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