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CN-122009193-A - Driving anti-skid torque control method and system based on road adhesion coefficient

CN122009193ACN 122009193 ACN122009193 ACN 122009193ACN-122009193-A

Abstract

The invention discloses a driving anti-skid torque control method and a driving anti-skid torque control system based on road adhesion coefficients, the control method comprises the steps of real-time monitoring of the running state of the vehicle, calculation of the slip rate of the driving wheel, estimation of the road surface adhesion coefficient, judgment of excessive slip of the driving wheel, starting of the driving anti-slip control flow, dynamic matching of the road surface adhesion coefficient and the torque reduction gradient, dynamic torque reduction execution, anti-slip control withdrawal and power recovery. By introducing a real-time estimation mechanism of road surface adhesion coefficient, the technical limitation that the traditional driving anti-skid control depends on a fixed torque reduction gradient is thoroughly broken, and a negative correlation dynamic matching mechanism of the road surface adhesion coefficient and the torque reduction gradient is established. Under the unsteady state working condition, multiple interference brought to road adhesion coefficient extraction thoroughly avoids the estimation distortion problem caused by vehicle body attitude deviation, transverse centrifugal force and ramp resistance, greatly improves the robustness, the accuracy and the working condition suitability of adhesion coefficient estimation, and provides reliable data support for subsequent dynamic torque reduction.

Inventors

  • ZHAO YA
  • ZHANG FAN
  • WANG XIAO
  • CHEN CHANGSHENG

Assignees

  • 奇瑞汽车股份有限公司

Dates

Publication Date
20260512
Application Date
20260331

Claims (10)

  1. 1. A driving anti-slip torque control method based on road adhesion coefficient, characterized by comprising: S1, monitoring the running state of a vehicle in real time, namely collecting vehicle state parameters in real time through a sensor cluster carried by the vehicle and a whole vehicle communication network, wherein the state parameters at least comprise a non-driving wheel rotating speed, a driving wheel rotating speed and an actual output torque of an engine; S2, calculating the slip rate of the driving wheel and estimating the road surface adhesion coefficient, namely, based on the vehicle state parameter acquired in the step S1, calculating the slip rate of the driving wheel in real time by comparing the difference value between the rotation speed of the driving wheel and the rotation speed of the non-driving wheel, and estimating the current road surface adhesion coefficient by the actual output torque of the engine, the rotation speed of the non-driving wheel, the rotation speed of the driving wheel, the slip rate of the driving wheel and the auxiliary reference parameter of the vehicle state; S3, judging excessive slip of the driving wheel and starting a driving anti-slip control flow, namely dynamically comparing the real-time driving wheel slip rate calculated in the step S2 with a preset driving wheel slip rate threshold value of a vehicle control system, judging that excessive slip of the driving wheel occurs and the tire adhesion is obviously reduced if the real-time driving wheel slip rate exceeds the preset driving wheel slip rate threshold value, and immediately triggering a driving anti-slip torque reduction control request to enter a torque adjustment flow; S4, dynamically matching the road surface adhesion coefficient with the torque reducing gradient, namely dynamically determining a target torque reducing gradient matched with the current road surface adhesion coefficient based on the current road surface adhesion coefficient estimated in the step S2, wherein the current road surface adhesion coefficient and the torque reducing gradient are in a negative correlation relation, namely the lower the estimated current road surface adhesion coefficient is, the larger the corresponding selected torque reducing gradient is, the higher the estimated current road surface adhesion coefficient is, the smaller the corresponding selected torque reducing gradient is, so that accurate fine adjustment of torque is realized, and power frustration and power loss are avoided; S5, executing dynamic torque reduction, exiting anti-slip control and recovering power, namely sending a torque adjustment instruction to an engine management system through a whole vehicle controller according to the target torque reduction gradient of the adaptive current road surface determined in the step S4, controlling the engine to gradually reduce output torque, monitoring the change of the slip rate of the driving wheel in real time in the whole torque reduction process until the slip rate of the driving wheel falls back into a preset threshold range of the slip rate of the driving wheel in real time, exiting torque reduction control, recovering the power output state of the vehicle, and synchronously updating the torque reduction gradient if the estimated current road surface adhesion coefficient in the torque reduction process changes in real time, so as to realize the whole dynamic adaptation.
  2. 2. The driving anti-skid torque control method based on road adhesion coefficients according to claim 1, wherein in step S4, the negative correlation between the current road adhesion coefficients and the torque reduction gradients is embodied as a gradient mapping function relationship, the gradient mapping function is a continuous function obtained by fitting optimal torque reduction gradient test values based on different road adhesion coefficient intervals, each torque reduction gradient value is determined through a plurality of rounds of whole vehicle calibration tests, and the corresponding torque reduction gradients are directly output through inputting road adhesion coefficient reference values to realize uninterrupted dynamic matching of the torque reduction gradients.
  3. 3. The driving anti-slip torque control method based on the road surface adhesion coefficient according to claim 1, wherein in step S2, the current road surface adhesion coefficient is estimated by the actual output torque of the engine, the non-driving wheel rotation speed, the driving wheel slip ratio, and the vehicle state auxiliary reference parameters, specifically comprising: Estimating road surface adhesion coefficients of steady-state driving scenes, wherein the steady-state driving scenes comprise uniform-speed driving scenes of the vehicle, calculating longitudinal acceleration of the vehicle by using actual vehicle speed obtained by converting rotation speeds of non-driving wheels and actual output torque of an engine, and reversely estimating the road surface adhesion coefficients according to the corresponding relation between the longitudinal acceleration and the road surface adhesion coefficients; The road surface adhesion coefficient estimation of the unsteady driving scene, the unsteady driving scene comprises a vehicle acceleration driving scene, a vehicle lane change driving scene, a vehicle turning driving scene and a vehicle jolt driving scene, an iterative estimation method based on the relation characteristic of the actual output torque of an engine and the slip rate of a driving wheel is adopted, namely, the relation characteristic inflection point of the actual output torque of the engine and the slip rate of the driving wheel is captured to obtain an initial estimation value of the adhesion coefficient, then a transverse motion interference correction term is calculated by combining the steering wheel corner, a braking intervention torque correction term is calculated by combining the braking pressure, and the transverse motion interference correction term and the braking intervention torque correction term are substituted into an iterative model to be subjected to successive closed loop iterative correction until an estimation result converges, so that the current road surface adhesion coefficient reference value is finally obtained.
  4. 4. The driving anti-slip torque control method based on road adhesion coefficient according to claim 3, wherein the lateral movement disturbance correction term and the braking disturbance torque correction term are substituted into the iterative model to perform successive closed loop iterative correction, and the calculation formula is: μ i+1 =μ 0 +Δ μlat,i +Δ μbrk,i ; Mu 0 is a relation characteristic inflection point of the actual output torque of the engine and the slip rate of the driving wheel to obtain an initial estimated value of an attachment coefficient, mu i+1 is a road surface attachment coefficient reference value of the (i+1) th iteration, delta μlat,i is a transverse motion interference correction term of the (i) th iteration, delta μbrk,i is a braking interference torque correction term of the (i) th iteration; The calculation formula for convergence of the estimation result is as follows: ∣μ i+1 μ i ∣≤ε; Wherein mu i+1 is a road surface adhesion coefficient reference value of i+1 iterations, mu i is a road surface adhesion coefficient reference value of the ith iteration, and epsilon is an iteration convergence threshold; The calculation formula of the transverse motion disturbance correction term is as follows: Δ μlat =f lat (δ,v act ,m,L); wherein f lat is a transverse motion interference solving function, delta is a steering wheel rotation angle, v act is an actual vehicle speed obtained by converting a non-driving wheel rotation speed, m is the mass of the whole vehicle, L is the wheelbase of the vehicle, and delta μlat is a transverse motion interference correcting term; the calculation formula of the brake intervention torque correction term is as follows: Δ μbrk =f brk (P brk ,A wheel ,r eff ); wherein f brk is a brake intervention torque calculation function, P brk is brake pressure, A wheel is brake cylinder effective area, r eff is tire effective rolling radius, and delta μbrk is a brake intervention torque correction term.
  5. 5. A driving anti-slip torque control method based on a road surface adhesion coefficient as claimed in claim 3, wherein in step S1, the auxiliary reference parameters further include a vehicle body pitch angle and a vehicle body roll angle; in step S2, the road surface adhesion coefficient estimation process of the unsteady driving scene is further added with a ramp resistance interference correction term and a roll centrifugal force interference correction term; And combining the vehicle body pitch angle with the slope resistance interference correction term, combining the vehicle body roll angle with the roll centrifugal force interference correction term, and substituting the slope resistance interference correction term, the roll centrifugal force interference correction term, the transverse motion interference correction term and the braking interference torque correction term into an iterative estimation model to participate in closed loop iterative correction so as to eliminate the interference of vehicle body posture deviation on the estimation precision of the road surface attachment coefficient.
  6. 6. The driving anti-slip torque control method based on road adhesion coefficient according to claim 5, wherein the slope resistance disturbance correction term, the roll centrifugal force disturbance correction term, the lateral movement disturbance correction term and the braking disturbance torque correction term are substituted into the iterative model together to participate in closed loop iterative correction, and the calculation formula is: μ i+1 =μ 0 +Δ μlat,i +Δ μbrk,i +Δ μslp,i +Δ μrol,i ; Wherein mu 0 is a relation characteristic inflection point of the actual output torque of the engine and the slip rate of the driving wheel to obtain an initial estimated value of an attachment coefficient, mu i+1 is a road surface attachment coefficient reference value of the ith iteration and 1 st iteration, delta μlat,i is a transverse motion interference correction term of the ith iteration, delta μbrk,i is a braking interference torque correction term of the ith iteration, delta μslp,i is a ramp resistance interference correction term of the ith iteration, delta μrol,i is a roll centrifugal force interference correction term of the ith iteration; The calculation formula for convergence of the estimation result is as follows: ∣μ i+1 μ i ∣≤ε; Wherein mu i+1 is a road surface adhesion coefficient reference value of i+1 iterations, mu i is a road surface adhesion coefficient reference value of the ith iteration, and epsilon is an iteration convergence threshold; The calculation formula of the transverse motion disturbance correction term is as follows: Δ μlat =f lat (δ,v act ,m,L); wherein f lat is a transverse motion interference solving function, delta is a steering wheel rotation angle, v act is an actual vehicle speed obtained by converting a non-driving wheel rotation speed, m is the mass of the whole vehicle, L is the wheelbase of the vehicle, and delta μlat is a transverse motion interference correcting term; the calculation formula of the brake intervention torque correction term is as follows: Δ μbrk =f brk (P brk ,A wheel ,r eff ); Wherein f brk is a brake intervention torque calculation function, P brk is brake pressure, A wheel is brake cylinder effective area, r eff is tire effective rolling radius, and delta μbrk is a brake intervention torque correction term; the calculation formula of the ramp resistance disturbance correction term is as follows: Δ μslp =f slp (θ,m,g); Wherein f slp is a ramp resistance interference solving function, θ is a vehicle body pitch angle, m is the mass of the whole vehicle, g is a gravitational acceleration constant, and delta μslp is a ramp resistance interference correcting term; the calculation formula of the roll centrifugal force interference correction term is as follows: Δ μrol =f rol (β,v act ,m,B); Wherein f rol is a roll centrifugal force interference solving function, beta is a vehicle body roll angle, v act is an actual vehicle speed obtained by converting the rotation speed of the non-driving wheels, m is the mass of the whole vehicle, B is the wheel tread of the vehicle, and delta μrol is a roll centrifugal force interference correction term.
  7. 7. The driving anti-slip torque control method based on the road surface adhesion coefficient according to claim 1, characterized by further comprising a state parameter preprocessing in step S1, specifically comprising: Sequentially performing first-order lag filtering, outlier removing and mean value smoothing on the collected rotation speed of the non-driving wheel and the rotation speed of the driving wheel, and removing abnormal data points generated by the electromagnetic interference of a sensor when the vehicle runs and bumps; And carrying out phase synchronization calibration on steering wheel rotation angles and braking pressures in the auxiliary reference parameters of the vehicle state, and ensuring that time stamps of all acquisition parameters are completely aligned.
  8. 8. A driving anti-slip torque control system based on road adhesion coefficient, comprising: The system comprises a vehicle state real-time monitoring module, a vehicle state auxiliary reference parameter acquisition module, a vehicle state real-time monitoring module and a vehicle state monitoring module, wherein the vehicle state real-time monitoring module is in communication connection with a sensor cluster carried by a vehicle and a whole vehicle communication network and is used for acquiring vehicle state parameters in real time, wherein the state parameters at least comprise a non-driving wheel rotating speed, a driving wheel rotating speed and an actual output torque of an engine; The road surface parameter calculation module is in signal connection with the vehicle state real-time monitoring module and is used for calculating real-time driving wheel slip rate by comparing the difference value of the driving wheel rotating speed and the non-driving wheel rotating speed based on the collected vehicle state parameters; The driving wheel slip judging and controlling triggering module is in signal connection with the road surface parameter resolving module and is used for dynamically comparing the calculated real-time driving wheel slip rate with a driving wheel slip rate threshold preset by a vehicle control system, judging that excessive slip occurs on the driving wheel and the tire adhesive force is obviously reduced if the real-time driving wheel slip rate exceeds the preset threshold, immediately generating and sending a driving anti-slip torque reducing control request, and starting a torque adjusting process; The torque reduction gradient dynamic matching module is respectively in signal connection with the road surface parameter calculating module and the driving wheel slip judging and controlling triggering module and is used for dynamically determining a target torque reduction gradient matched with the current road surface attachment coefficient based on the estimated current road surface attachment coefficient, wherein the current road surface attachment coefficient and the torque reduction gradient are in a negative correlation relationship, namely, the lower the estimated current road surface attachment coefficient is, the larger the corresponding selected torque reduction gradient is, the higher the estimated current road surface attachment coefficient is, the smaller the corresponding selected torque reduction gradient is, the accurate fine adjustment of torque is realized, and the power frustration and power loss are avoided; the dynamic torque reduction execution and closed loop regulation module is respectively in signal connection with the torque reduction gradient dynamic matching module and the engine management system and is used for sending a torque regulation instruction to the engine management system through the whole vehicle controller according to the determined target torque reduction gradient adapted to the current road surface so as to control the engine to gradually reduce the output torque, the real-time monitoring of the change of the slip rate of the driving wheel is realized in the whole process of torque reduction until the slip rate of the driving wheel falls back into the range of the preset slip rate threshold value of the driving wheel in real time, the torque reduction control is stopped and the anti-slip process is exited, the power output state of the vehicle is restored, and if the estimated current road surface attachment coefficient in the torque reduction process changes in real time, the torque reduction gradient is updated in a synchronous linkage way so as to realize the dynamic adaptation of the whole road condition.
  9. 9. The traction torque control system according to claim 8, wherein the road surface parameter calculation module comprises a steady-state road surface traction coefficient estimation unit and an unsteady-state road surface traction coefficient iterative estimation unit; The steady-state road surface adhesion coefficient estimation unit is adapted to a vehicle uniform-speed running scene, the built-in algorithm is used for obtaining an actual vehicle speed through conversion of the rotation speed of the non-driving wheels, the longitudinal acceleration of the vehicle is calculated through the actual vehicle speed and the actual output torque of the engine, and then the road surface adhesion coefficient under the steady-state scene is estimated reversely according to the corresponding relation between the longitudinal acceleration and the road surface adhesion coefficient; The unsteady road adhesion coefficient iterative estimation unit is adapted to a vehicle acceleration driving scene, a vehicle lane change driving scene, a vehicle turning driving scene and a vehicle bump driving scene, and adopts iterative closed loop estimation logic, namely, firstly capturing a relation characteristic inflection point of the actual output torque of an engine and the slip rate of a driving wheel to obtain an adhesion coefficient initial estimation value; The transverse motion interference correction term and the braking intervention torque correction term are substituted into the iterative model to carry out successive closed loop iterative correction, and the calculation formula is as follows: μ i+1 =μ 0 +Δ μlat,i +Δ μbrk,i ; Mu 0 is a relation characteristic inflection point of the actual output torque of the engine and the slip rate of the driving wheel to obtain an initial estimated value of an attachment coefficient, mu i+1 is a road surface attachment coefficient reference value of the (i+1) th iteration, delta μlat,i is a transverse motion interference correction term of the (i) th iteration, delta μbrk,i is a braking interference torque correction term of the (i) th iteration; The calculation formula for convergence of the estimation result is as follows: ∣μ i+1 μ i ∣≤ε; Wherein mu i+1 is a road surface adhesion coefficient reference value of i+1 iterations, mu i is a road surface adhesion coefficient reference value of the ith iteration, and epsilon is an iteration convergence threshold; The calculation formula of the transverse motion disturbance correction term is as follows: Δ μlat =f lat (δ,v act ,m,L); wherein f lat is a transverse motion interference solving function, delta is a steering wheel rotation angle, v act is an actual vehicle speed obtained by converting a non-driving wheel rotation speed, m is the mass of the whole vehicle, L is the wheelbase of the vehicle, and delta μlat is a transverse motion interference correcting term; the calculation formula of the brake intervention torque correction term is as follows: Δ μbrk =f brk (P brk ,A wheel ,r eff ); wherein f brk is a brake intervention torque calculation function, P brk is brake pressure, A wheel is brake cylinder effective area, r eff is tire effective rolling radius, and delta μbrk is a brake intervention torque correction term.
  10. 10. The driving anti-skid torque control system based on road adhesion coefficient according to claim 9, wherein the vehicle state real-time monitoring module is further provided with a vehicle body posture acquisition subunit for additionally acquiring a vehicle body pitch angle and a vehicle body roll angle as supplementary auxiliary reference parameters; The unsteady road surface attachment coefficient iterative estimation unit is also integrated with a ramp resistance interference solution operator unit and a rolling centrifugal force interference solution operator unit, which are respectively used for combining a vehicle body pitch angle to calculate a ramp resistance interference correction item and combining a vehicle body rolling angle to calculate a rolling centrifugal force interference correction item, and the ramp resistance interference correction item, the rolling centrifugal force interference correction item, the transverse motion interference correction item and the braking interference torque correction item are jointly substituted into an iterative model in the iterative estimation process to participate in closed loop iterative correction, so that the interference of vehicle body attitude deviation on road surface attachment coefficient estimation precision is eliminated; the slope resistance interference correction term, the rolling centrifugal force interference correction term, the transverse motion interference correction term and the braking interference torque correction term are jointly substituted into the iterative model to participate in closed loop iterative correction, and a calculation formula is as follows: μ i+1 =μ 0 +Δ μlat,i +Δ μbrk,i +Δ μslp,i +Δ μrol,i ; Wherein mu 0 is a relation characteristic inflection point of the actual output torque of the engine and the slip rate of the driving wheel to obtain an initial estimated value of an attachment coefficient, mu i+1 is a road surface attachment coefficient reference value of the ith iteration and 1 st iteration, delta μlat,i is a transverse motion interference correction term of the ith iteration, delta μbrk,i is a braking interference torque correction term of the ith iteration, delta μslp,i is a ramp resistance interference correction term of the ith iteration, delta μrol,i is a roll centrifugal force interference correction term of the ith iteration; The calculation formula for convergence of the estimation result is as follows: ∣μ i+1 μ i ∣≤ε; Wherein mu i+1 is a road surface adhesion coefficient reference value of i+1 iterations, mu i is a road surface adhesion coefficient reference value of the ith iteration, and epsilon is an iteration convergence threshold; the calculation formula of the ramp resistance disturbance correction term is as follows: Δ μslp =f slp (θ,m,g); Wherein f slp is a ramp resistance interference solving function, θ is a vehicle body pitch angle, m is the mass of the whole vehicle, g is a gravitational acceleration constant, and delta μslp is a ramp resistance interference correcting term; the calculation formula of the roll centrifugal force interference correction term is as follows: Δ μrol =f rol (β,v act ,m,B); Wherein f rol is a roll centrifugal force interference solving function, beta is a vehicle body roll angle, v act is an actual vehicle speed obtained by converting the rotation speed of the non-driving wheels, m is the mass of the whole vehicle, B is the wheel tread of the vehicle, and delta μrol is a roll centrifugal force interference correction term.

Description

Driving anti-skid torque control method and system based on road adhesion coefficient Technical Field The invention relates to the technical field of vehicle electronic control, in particular to a driving anti-skid torque control method and system based on road adhesion coefficient. Background The driving anti-skid system (DTCS) is an important component of the electronic stability system of the vehicle, and the core is that when the driving wheel excessively slips, the adhesion force of the driving wheel is recovered through torque reduction or braking, so that the driving stability and the operability of the vehicle are ensured. The existing DTCS torque control mostly adopts a preset fixed torque reduction gradient strategy, and the torque is reduced according to the gradient after the system detects that the slip rate exceeds the threshold value. The strategy has the obvious defects that firstly, the adaptability is poor, the adhesion coefficient difference of different roads such as ice surface, dry asphalt and the like is large, the fixed gradient is difficult to adapt to all road conditions, secondly, the drivability is poor, the high adhesion road surface torque reduction gradient is too large, the pause is easy to generate, the slip inhibition is slow and the power loss is high when the low adhesion road surface gradient is too small, thirdly, the control efficiency is low, the optimal adhesion recovery requirements of different roads cannot be matched, and the requirements of the low adhesion road surface torque reduction and the high adhesion road surface accurate torque adjustment are difficult to be met. Disclosure of Invention Aiming at the defects of the prior art, the invention designs a driving anti-skid torque control method based on road adhesion coefficient, which comprises the following steps: S1, monitoring the running state of the vehicle in real time, namely collecting the state parameters of the vehicle in real time through a sensor cluster carried by the vehicle and a whole vehicle communication network, wherein the state parameters at least comprise the rotation speed of a non-driving wheel, the rotation speed of a driving wheel and the actual output torque of an engine. And synchronously acquiring auxiliary reference parameters of the vehicle state, wherein the auxiliary reference parameters at least comprise steering wheel rotation angle and braking pressure. S2, calculating the slip rate of the driving wheel and estimating the road surface adhesion coefficient, namely, based on the vehicle state parameter acquired in the step S1, calculating the slip rate of the driving wheel in real time by comparing the difference value between the rotation speed of the driving wheel and the rotation speed of the non-driving wheel, and estimating the current road surface adhesion coefficient by the actual output torque of the engine, the rotation speed of the non-driving wheel, the rotation speed of the driving wheel, the slip rate of the driving wheel and the auxiliary reference parameter of the vehicle state. S3, judging excessive slip of the driving wheel and starting a driving anti-slip control flow, namely dynamically comparing the real-time driving wheel slip rate calculated in the step S2 with a preset driving wheel slip rate threshold value of a vehicle control system, judging that excessive slip of the driving wheel occurs and the adhesion of the tire is obviously reduced if the real-time driving wheel slip rate exceeds the preset driving wheel slip rate threshold value, immediately triggering a driving anti-slip torque-reducing control request, and entering a torque adjusting flow. If the real-time driving wheel slip rate does not exceed the preset driving wheel slip rate threshold value, the current vehicle power output state is maintained, and the power requirement and the running stability of normal running of the vehicle are ensured. And S4, dynamically matching the road surface adhesion coefficient with the torque reducing gradient, namely dynamically determining the target torque reducing gradient matched with the current road surface adhesion coefficient based on the current road surface adhesion coefficient estimated in the step S2, wherein the current road surface adhesion coefficient and the torque reducing gradient are in a negative correlation, namely the lower the estimated current road surface adhesion coefficient is, the larger the corresponding selected torque reducing gradient is, the higher the estimated current road surface adhesion coefficient is, the smaller the corresponding selected torque reducing gradient is, so that accurate fine adjustment of torque is realized, and power frustration and power loss are avoided. S5, executing dynamic torque reduction and exiting anti-slip control and recovering power, namely sending a torque adjustment instruction to an engine management system through a whole vehicle controller according to the target torque reduction gradi