Load estimation method and system for vehicle electronic brake system

Abstract

The invention belongs to the technical field of intelligent automobiles, and particularly relates to a load estimation method and system for a vehicle electronic braking system. The method aims at solving the core problems that an existing vehicle load estimation technology seriously depends on specific ideal working conditions such as uniform acceleration and uniform deceleration, so that estimation lags behind, and results are not accurate. The method comprises the following steps of: judging parameters such as accelerator pedal opening, vehicle speed, steering wheel angle, acceleration and road slope condition to confirm that the vehicle is in an estimation triggering condition of stable acceleration, and then calculating theoretical acceleration corresponding to all assumed weights in parallel in a no-load to full-load mass interval; and finally, matching the theoretical acceleration with a measured value and selecting a solution with the minimum error as a load result, so that the real-time performance and accuracy of load estimation are remarkably improved, and the precision of self-adaptive braking force adjustment of the electronic braking system is further improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of intelligent vehicles, and particularly relates to a load estimation method and system for a vehicle electronic braking system. BACKGROUND

[0002] The traditional air brake system has a significant difference in deceleration corresponding to the same brake pedal position when the commercial vehicle is full load and empty load. This difference leads to an error in the driver's braking feeling, so that the driver will feel inconsistent braking effect each time. With the increasing demand for braking safety performance of commercial vehicles, the commercial vehicle electronic braking system (EBS) emerges as the times require. The commercial vehicle EBS system calculates the required braking force according to the vehicle weight to achieve consistent braking feeling under different load conditions. The system adjusts according to the vehicle weight to ensure the consistency of the driver's braking experience under different load conditions. Therefore, the vehicle weight estimation is a key problem in the commercial vehicle electronic braking system.

[0003] The current vehicle weight estimation method of the commercial vehicle EBS system often needs to be accurately estimated under specific working conditions, such as uniform acceleration process or uniform deceleration process. If the uniform acceleration or uniform deceleration working condition is incorrectly identified, the result of each calculation may have a large difference, resulting in a large fluctuation in the detection of the vehicle weight. Moreover, the driver may not drive according to the demand for a long time, and the uniform acceleration or uniform deceleration working condition may not appear, which will cause the estimation time to be too long. If the braking force of the EBS system is adjusted based on this type of vehicle weight detection, it will greatly affect the driver's control of the brake.

[0004] Therefore, the application is proposed. SUMMARY

[0005] An object of the application is to solve the core problem that the existing vehicle load estimation technology seriously depends on specific ideal working conditions such as uniform acceleration and uniform deceleration, resulting in estimation lag and inaccurate results.

[0006] To achieve the above object, the application provides a load estimation method for a vehicle electronic braking system, comprising:

[0007] Based on the current running parameters of the vehicle, it is confirmed whether the current running state of the vehicle meets the preset load estimation trigger condition; the running parameters include the accelerator pedal opening degree, the vehicle speed, the steering wheel angle, the vehicle acceleration and the road slope;

[0008] If it is met, the theoretical acceleration corresponding to multiple assumed weights in the empty mass to full mass interval is calculated based on the vehicle dynamics model;

[0009] Compare all the theoretical accelerations with the measured acceleration, select the assumed weight with the least error matching the measured acceleration from the plurality of assumed weights as the final load estimation value.

[0010] Further, the step of confirming whether the current vehicle operating state meets the preset load estimation triggering condition comprises: acquiring current vehicle operating parameters; the operating parameters include accelerator pedal opening, vehicle speed, steering wheel angle, vehicle acceleration, and road slope; determining the current vehicle operating state according to the current vehicle operating parameters; and confirming whether the preset load estimation triggering condition is met according to the current vehicle operating state; wherein the operating state includes braking state, non-braking state, acceleration state, deceleration state, constant speed state, straight driving state, curve driving state, and slope state of the driving road.

[0011] Further, the confirmation of whether the preset load estimation triggering condition is met is performed in sequence according to the following logical steps: in response to the current vehicle being in the non-braking state, it is determined whether the current vehicle is in the non-low speed state driving; in response to the current vehicle being in the non-low speed state driving, it is determined whether the current vehicle is in the straight driving state; in response to the current vehicle being in the straight driving state, it is determined whether the current vehicle is in the acceleration state driving; in response to the current vehicle being in the acceleration state driving, it is determined whether the current driving road condition is the non-slope state; and in response to the current driving road condition being the non-slope state, the load estimation triggering condition is met.

[0012] Further, the step of determining the current vehicle operating state according to the current vehicle operating parameters comprises: determining whether the accelerator pedal opening is greater than a first threshold value; if the accelerator pedal opening is greater than the first threshold value, the current vehicle is in the non-braking state; determining whether the vehicle speed is greater than a second threshold value; if the vehicle speed is greater than the second threshold value, the current vehicle is in the non-low speed state driving; determining whether the absolute value of the steering wheel angle is less than a third threshold value; if the absolute value of the steering wheel angle is less than the third threshold value, the current vehicle is in the straight driving state; determining whether the vehicle acceleration is greater than a fourth threshold value; if the vehicle acceleration is greater than the fourth threshold value, the current vehicle is in the acceleration state driving; and determining whether the absolute value of the road slope is less than a fifth threshold value; if the absolute value of the road slope is less than the fifth threshold value, the current driving road condition is the non-slope state.

[0013] Further, the step of calculating the theoretical acceleration corresponding to each assumed weight in the empty mass to full mass interval based on the vehicle dynamics model comprises: inputting each assumed weight in the empty mass to full mass interval into the vehicle dynamics model as shown in the following formula to obtain a plurality of theoretical accelerations ​, formula as follows:

[0014] ; wherein, is the current driving force of the vehicle; is the current air resistance of the vehicle; is the current rolling resistance of the vehicle; is the acceleration resistance coefficient.

[0015] Further, the step of calculating the current driving force of the vehicle comprises: obtaining the current torque of the engine of the vehicle , calculating the current driving force of the vehicle according to the current torque of the engine , according to the following formula: ; wherein, is the transmission efficiency of the transmission system of the vehicle; is the total transmission ratio of the transmission system.

[0016] Further, the step of calculating the current air resistance of the vehicle comprises: obtaining the current speed of the vehicle , calculating the current air resistance of the vehicle according to the current speed of the vehicle , according to the following formula:

[0017] ; wherein, is the air resistance coefficient; is the windward area of the vehicle.

[0018] Further, the step of calculating the current rolling resistance of the vehicle comprises: calculating the current rolling resistance of the vehicle according to the assumed weight , according to the following formula: ; wherein, is the acceleration of gravity; is the rolling resistance coefficient.

[0019] Further, the step of comparing all the theoretical accelerations with the measured acceleration, selecting the assumed weight with the minimum matching error from the multiple assumed weights as the final load estimation value, comprises: obtaining the actual acceleration of the vehicle; calculating the square error of each theoretical acceleration and actual acceleration respectively; determining the minimum square error from all the square errors; taking the multiple assumed weights corresponding to the minimum square error as the final load estimation value.

[0020] In some other embodiments, an electronic brake system (EBS) is provided, comprising a load estimation method for a vehicle electronic brake system as described in any one of the above embodiments. ​​​

[0021] Based on the foregoing description, those skilled in the art can understand that the present application confirms the estimated triggering condition of the vehicle in stable acceleration by judging the parameters such as the accelerator pedal opening, the vehicle speed, the steering wheel angle, the acceleration, and the road slope condition, then calculates the theoretical acceleration corresponding to all assumed weights in parallel within the empty-to-full load mass interval, and finally selects the solution with the minimum error as the load result by matching the theoretical acceleration with the measured value, thereby effectively overcoming the excessive dependence of the traditional method on the ideal working condition, significantly improving the real-time performance and accuracy of the estimation, and further improving the precision of the adaptive brake force regulation of the electronic brake system. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings, which are part of the present application, serve to provide a further understanding of the present application, and the illustrative embodiments of the present application and their descriptions serve to explain the present application but do not constitute an improper limitation of the present application. Obviously, the drawings in the following description are only some embodiments, and other drawings can be obtained from these drawings by those of ordinary skill in the art without creative labor. In the drawings:

[0023] Figure 1 Flowchart of the load estimation method for the vehicle electronic brake system in some embodiments of the present application. DETAILED DESCRIPTION

[0024] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments will be described clearly and completely below with reference to the drawings of the embodiments of the present application. The following embodiments are used to explain the present application but not to limit the scope of the present application.

[0025] Those skilled in the art should understand that the embodiments described below are only a part of the embodiments of the present application, not all the embodiments of the present application, and the part of the embodiments are intended to explain the technical principles of the present application, not to limit the protection scope of the present application. Based on the embodiments provided by the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor should still fall within the protection scope of the present application.

[0026] The load estimation method for the vehicle electronic brake system in some embodiments of the present application will be described in detail below with reference to Figure 1 . Figure 1 Flowchart of the load estimation method for the vehicle electronic brake system in some embodiments of the present application.

[0027] In some embodiments of the present application, an electronic brake system (EBS) is provided, which automatically adjusts the braking force ratio of front and rear axles in real time according to the vehicle load, speed, and turning conditions, so that the adhesion of each wheel is fully utilized, thereby minimizing the braking distance. By optimizing the force distribution, the over-wear and overheating of some wheels (especially the rear wheels when empty) are avoided, the "thermal decay" phenomenon caused by brake overheating is effectively prevented, and the service life of brake pads, tires, and other components is prolonged.

[0028] Generally, the EBS system is an integrated platform for anti-lock braking system (ABS), drive slip regulation system (ASR), and electronic stability control system (ESC) functions. EBS can more quickly and accurately control the braking force of each wheel, prevent wheel lock and skid during emergency braking, and ensure the steering ability.

[0029] The function of the anti-lock braking system (ABS) is to prevent wheel lock (i.e., the tire does not rotate and slides on the road) during emergency braking. Wheel lock can easily cause the vehicle to lose steering ability, and the locked wheel cannot provide lateral force, so the vehicle will slide in the inertial direction and cannot avoid obstacles; at the same time, on most road surfaces, the rolling friction braking force is greater than the sliding friction, which will also make the vehicle braking distance longer, so that the vehicle cannot brake in time; in addition, it will also cause the vehicle to lose control, for example, the rear wheels are easy to lock first, which can cause the vehicle to spin. The anti-lock braking system (ABS) includes a wheel speed sensor, an electronic control unit (ECU), and a hydraulic / pneumatic regulating valve. The wheel speed sensor is used to monitor the real-time speed of each wheel. The electronic control unit (ECU) is used to analyze the wheel speed signal, and if it detects that the speed of a certain wheel is rapidly decreasing (i.e., about to lock), it will immediately issue an instruction. The hydraulic / pneumatic regulating valve is used to execute the ECU's instruction to perform a "pressure preservation-decompression-pressurization" cycle operation on the brake wheel cylinder at a very high frequency (dozens or even hundreds of times per second), which is equivalent to artificial "point braking", but the speed and accuracy are far superior to humans, so that the wheel is always in a "rolling and sliding" critical state, and the slip rate is maintained in the optimal interval.

[0030] The drive anti-slip system (ASR) is also called traction control system (TCS), which acts on the vehicle starting or accelerating, if the drive wheel slips, EBS can actively brake the wheel and transfer power to the wheel with adhesion to prevent the drive wheel (such as the rear wheel of the rear-wheel drive car) from slipping. Drive wheel slip is easy to cause vehicle out of control, that is, when accelerating on low adhesion road surface (such as ice, rain), drive wheel slip may cause vehicle sideslip; also makes the power of the vehicle appear loss, that is, the slipping wheel cannot effectively transmit the engine power to the road surface, resulting in powerless acceleration. ASR shares wheel speed sensor and ECU with ABS, and compares the speed of the drive wheel and the non-drive wheel through the ECU. If the drive wheel speed is much higher than the non-drive wheel, it means that the drive wheel is slipping. At this time, the ECU instructs to apply appropriate brake force to the slipping drive wheel to inhibit its rotation, so as to play the role of brake intervention; at the same time, the ECU will request the engine control unit (ECU) to reduce the fuel injection amount or delay ignition, reduce the engine torque output, and reduce the power of the slipping wheel from the source.

[0031] The vehicle body electronic stability system (ESC) is also called ESP, VSC, etc. Different manufacturers call it differently, which acts on the vehicle when the system detects that the vehicle has the risk of losing control (such as fishtailing when turning sharply), EBS will actively and differentially brake the single wheel, generate a reverse torque, and "pull back" the vehicle to the correct trajectory. ESC adds lateral acceleration sensor and yaw rate sensor on the basis of ABS / ASR. The lateral acceleration sensor detects whether the vehicle is subjected to lateral force. The yaw rate sensor detects the rotation speed of the vehicle around the vertical axis (i.e. whether the vehicle head is turning left or right). The ECU reads the signal of the steering wheel angle sensor, knows the driving intention of the driver, and through the lateral acceleration and yaw rate sensor, the ECU senses the actual state of the vehicle. If the actual state deviates from the driving intention (for example, the driver wants to go straight, but the vehicle starts to fishtail), the ECU immediately judges that the vehicle is out of control. The system will not go through the driver, but directly brake the single wheel to generate a reverse torque and "pull" the vehicle back to the correct trajectory, that is, to brake the front wheel on the outside of the curve to correct fishtailing (oversteering); brake the rear wheel on the inside of the curve to correct the nose (understeering). At the same time, the system will request to reduce the engine torque to assist in stabilizing the vehicle.

[0032] Since the vehicle load estimation of the present application relies on the longitudinal dynamics model, when the vehicle is in the state of coasting, idling or braking during operation, the vehicle load estimation is not required, so it is necessary to determine whether the vehicle is in the non-braking state and to use it as one of the conditions for triggering load estimation; when the vehicle is in a low-speed or stationary state, the signal noise is large at this time, and the calculation is inaccurate, so it is necessary to set a speed threshold to filter out the low-speed working condition, so as to determine that the vehicle is in a non-low-speed state as one of the conditions for triggering load estimation; when the vehicle is in a non-straight driving state, i.e. the vehicle is turning, the lateral dynamics becomes complex during turning, and factors such as centrifugal force and left and right wheel load transfer will seriously interfere with the estimation accuracy of the longitudinal dynamics model, so in order to ensure the estimation accuracy, it is necessary to determine that the vehicle is in a straight driving state; when the vehicle is in a uniform speed or small deceleration state, since the acceleration process is the premise of the dynamics model to reverse the mass, the case of small deceleration often appears that the acceleration signal may be overwhelmed by noise, and the equation has low sensitivity to mass change, so the estimation result is unreliable, therefore it is necessary to determine that the vehicle is in a clear acceleration state to further improve the load estimation accuracy; when the vehicle is driving on a road with a significant slope, the model calculation accuracy will also be greatly affected by gravity, so it is necessary to exclude the case of significant slope to improve the load estimation accuracy.

[0033] Therefore, in the present application, the EBS system needs to obtain the running state of the vehicle, and determine whether to trigger the load estimation process according to the running state, so as to exclude the above-mentioned cases and perform load estimation. Therefore, at least the acceleration pedal opening, vehicle speed, steering wheel angle, vehicle acceleration and road slope and other running parameters need to be detected and judged to determine the triggering condition.

[0034] The acceleration pedal opening is directly detected by an acceleration pedal position sensor, which is directly integrated in the acceleration pedal assembly inside the cab, and the EBS system reads the signal from the bus and judges whether the vehicle is in the driving (non-braking) state. The acceleration pedal position sensor can be configured as a double potentiometer or a non-contact Hall sensor, when the driver steps on the pedal, the resistance value of the potentiometer or the magnetic field strength of the Hall element will change, the sensor converts this mechanical displacement into a linear voltage signal or a digital signal (such as a PWM signal), then the engine ECU reads the signal and analyzes it as an opening of 0% to 100%. 0% represents the pedal is completely released, and 100% represents the pedal is stepped to the bottom.

[0035] The acceleration pedal opening can be set as a single threshold or a double threshold, and the pedal opening judgment process can effectively filter out the case that the driver's foot accidentally touches the pedal or the pedal signal fluctuates slightly, so that it can reliably determine whether the vehicle is in the braking or non-braking state.

[0036] Preferably, the accelerator pedal opening degree is set as a single threshold, and the threshold value can be set as 2% to 5%, preferably, the present application sets the threshold value as 2%, and the threshold value is recorded as a first threshold.

[0037] The EBS system is configured to obtain the current accelerator pedal opening degree of the vehicle, and determine whether the current accelerator pedal opening degree is greater than the first threshold. If it is greater, it means that the vehicle is in a non-braking state, and the driver may have an acceleration intention, allowing the system to enter the subsequent condition judgment, i.e., sequentially performing speed, steering wheel angle, acceleration, and road slope judgment. If the accelerator pedal opening degree is less than the first threshold, it means that the driver is in a coasting, idling, or braking state, and the estimation condition is not met, the system is reset or waits, and the accelerator pedal opening degree judgment is started every interval of a predetermined time, which can be set as 3 to 5 seconds, and the cycle is repeated.

[0038] When the accelerator pedal is set as a double threshold, the double threshold includes two cases. Case one, a low threshold and a high threshold are set, the low threshold is used to determine whether to enter the acceleration working condition and start load estimation. The high threshold is used to determine whether it is "rapid acceleration" or "heavy load acceleration", and the engine torque output is more stable during heavy load acceleration, and the load estimation condition is better. Case two, an opening threshold and a closing threshold are set to avoid frequent switching between "estimation" and "non-estimation" states of the system caused by slight fluctuations of the accelerator pedal near the threshold value, thereby improving the stability of the system.

[0039] Specifically, the double threshold includes a low threshold and a high threshold, the low threshold can be set as 3% to 5%, preferably, the low threshold is set as 3%, and the low threshold is recorded as a first pedal threshold, and the high threshold can be set as 30% to 35%, preferably, the high threshold can be set as 30%, and the high threshold is recorded as a second pedal threshold.

[0040] The EBS system is configured to obtain the current accelerator pedal opening degree of the vehicle, and determine whether the current accelerator pedal opening degree is greater than the first pedal threshold. If the accelerator pedal opening degree is less than the first pedal threshold, the current accelerator pedal opening degree is re-obtained, and the cycle is repeated. If the current accelerator pedal opening degree is greater than the first pedal threshold, it means that the vehicle is in a non-braking state. At this time, it is determined whether the current accelerator pedal opening degree is greater than the second pedal threshold. If it is greater, it means that the vehicle is in rapid acceleration or heavy load acceleration, and only subsequent steering wheel angle and road slope judgment is needed, without subsequent speed and acceleration judgment. If the current accelerator pedal opening degree is less than the second pedal threshold, the current accelerator pedal opening degree is continuously obtained, and it is determined whether the current accelerator pedal opening degree is greater than the second pedal threshold, and the cycle is repeated.

[0041] Specifically, the double threshold includes an opening threshold and a closing threshold, the opening threshold can be set to 2% to 5%, preferably, the opening threshold is set to 3%, and the opening threshold is recorded as a third pedal threshold. The closing threshold can be set to 1.5% to 3%, preferably, the closing threshold is set to 1.5%, and the closing threshold is recorded as a fourth pedal threshold.

[0042] The EBS system is configured to: obtain the current accelerator pedal opening, judge whether the accelerator pedal opening increases from below the third pedal threshold to above the third pedal threshold, when the accelerator pedal opening increases from below the third pedal threshold to above the third pedal threshold, the system starts the subsequent vehicle speed, steering wheel angle, acceleration and road slope judgment; continue to obtain the current accelerator pedal opening, judge whether the accelerator pedal opening falls below the fourth pedal threshold, when the accelerator pedal opening falls below the fourth pedal threshold, the system stops the subsequent judgment or load estimation, and re-performs the accelerator pedal judgment, and so on. By setting the opening threshold and the closing threshold, the state jitter caused by the frequent switching between "estimation" and "non-estimation" states of the system when the pedal slightly fluctuates near the threshold value is effectively avoided.

[0043] The vehicle speed parameter is detected by a wheel speed sensor installed near the hub of each wheel, aligned with a magnetic tooth ring (target wheel) installed on the wheel bearing or transmission shaft. The vehicle speed parameter is the core parameter of all dynamic control systems, which is applied to ABS, ASR, ESC, EBS and instrument panel modules. The wheel speed sensor can adopt magneto or Hall principle. Using magneto principle: when the tooth ring rotates with the wheel, the teeth and tooth gaps alternately pass through the sensor probe, causing the magnetic flux to change, generating an alternating sinusoidal voltage signal in the sensor coil. The ECU calculates the number of pulses per unit time to get the wheel speed. Using Hall principle: the same tooth ring movement is detected, but the output is a clear square wave digital signal, which has stronger anti-interference ability and is more accurate at low speed. The ECU calculates the actual speed of the vehicle according to the speed of the non-driving wheel (or the average value of all wheel speeds) and the rolling circumference of the wheel, i.e. vehicle speed = wheel speed x wheel circumference.

[0044] The vehicle speed can be set to a single threshold value, and the vehicle speed is used to filter out the inaccurate factors of deceleration calculation at low speed. The vehicle speed threshold value can be set to 5km / h to 10km / h, preferably, the vehicle speed threshold value is set to 5Km / h, and the vehicle speed threshold value is recorded as a second threshold value.

[0045] The EBS system is configured to: acquire the current vehicle speed, determine whether the current vehicle speed is greater than a second threshold value, if greater, it means that the vehicle has left the unstable working conditions such as low-speed creeping, starting or moving, and entered the stable driving state, at this time, the wheel speed signal and the acceleration signal are relatively stable and reliable, allowing the system to proceed to the subsequent steering wheel angle judgment process; if the vehicle speed is less than the second threshold value, it means that the vehicle is in a low-speed or stationary state, at this time the signal noise is large and the calculation is inaccurate, the system does not estimate, and the system returns to the accelerator pedal opening detection / judgment step, and re-performs the accelerator pedal opening detection / judgment, and so on. Through the vehicle speed judgment, the low-speed working condition can be effectively filtered out. Since the dynamics model is not accurate under low-speed working condition, and the demand for load information for EBS braking force regulation is not urgent, therefore, through this step of filtering, the operation cost can be saved, and the accuracy of load estimation can be improved.

[0046] The steering wheel angle parameter is detected by a steering wheel angle sensor installed on the steering column, usually below the steering wheel, integrated with the clock spring. The steering wheel angle parameter is the most critical signal for judging the steering intention of the driver, and is applied in the vehicle body electronic stability system ESC. The steering wheel angle parameter detection usually adopts photoelectric encoder technology, the sensor has an encoding disc inside which rotates synchronously with the steering wheel shaft, and the disc is engraved with precise slits. There are light-emitting diodes (LEDs) and phototransistors on both sides of the encoding disc. When the steering wheel rotates, the encoding disc rotates, the light is intermittently blocked, and the phototransistors will generate two pulse sequences with a phase difference. The ECU can not only accurately calculate the absolute rotation angle of the steering wheel, but also determine the direction of rotation (left or right) by analyzing the number and phase difference of the two pulse sequences.

[0047] The steering wheel angle is set as a single threshold, and the steering wheel threshold value can be set to 3° to 5°, preferably, the steering wheel threshold value is set to 5°, and the steering wheel threshold value is denoted as a third threshold value.

[0048] The EBS system is configured to: acquire the current steering wheel angle of the vehicle, judge whether the absolute value of the current steering wheel angle is less than a third threshold value, if the absolute value of the current steering wheel angle is less than the third threshold value, it indicates that the vehicle is in a straight driving state or an approximate straight driving state, at this time, the vehicle is simply stressed, there is no obvious centrifugal force, the longitudinal dynamics model (only considering the force in the front and rear directions) is accurate enough, and is suitable for load estimation, that is, the EBS system performs subsequent acceleration and road slope judgment; if the absolute value of the current steering wheel angle is greater than or equal to the third threshold value, it indicates that the vehicle is turning, at this time, the lateral dynamics becomes complex, and factors such as centrifugal force and left and right wheel load transfer will seriously interfere with the estimation accuracy based on the longitudinal dynamics model, at this time, the system load estimation result is poor, that is, the EBS system returns to the accelerator pedal opening degree judgment step, and the cycle is repeated. Since the present application is based on the longitudinal dynamics model, straight driving is the best working condition to ensure that the model is valid, and the steering wheel angle can be used to directly judge whether the vehicle is in a straight driving state, thereby reducing the probability of false triggering and effectively improving the accuracy of the load estimation structure.

[0049] The vehicle acceleration parameter is detected by an acceleration sensor, which is usually installed near the center of gravity of the vehicle, such as under the vehicle compartment floor or on the transmission tunnel, and is integrated with the ESC / EBS control unit to reduce vibration interference. The acceleration sensor is used to directly perceive the motion change of the vehicle and is applied to ESC, EBS, airbag system and the like. The vehicle acceleration parameter detection is based on a MEMS (Micro-Electro-Mechanical System) chip, which has a small and movable "mass block" inside. When the vehicle accelerates or decelerates, according to the law of inertia, the mass block will be subjected to a force in the opposite direction and will undergo a small displacement, which will be detected by the capacitor plate on the chip (the capacitance value changes) and converted into an electric signal proportional to the acceleration. The acceleration sensor that measures the front and rear direction acceleration is called longitudinal acceleration sensor, which directly outputs the acceleration value in m / s² or g.

[0050] The acceleration is set as a single threshold, and the acceleration threshold value can be set to 0.1 m / s² to 0.3 m / s², preferably, the acceleration threshold value is set to 0.1 m / s², and the acceleration threshold value is recorded as a fourth threshold value.

[0051] The EBS system is configured to: acquire the current vehicle acceleration, judge whether the current vehicle acceleration is greater than the fourth threshold value, if the current vehicle acceleration is greater than the fourth threshold value, it indicates that the vehicle is in an acceleration process. At this time, the dynamics equation F drive -F resistanceThe acceleration a in = m*a is a positive value large enough to make the equation sensitive to the change of mass m, thus ensuring the accuracy of the estimation. When the current vehicle acceleration is less than or equal to the fourth threshold value, it indicates that the vehicle is in a state of uniform speed or small deceleration. At this time, the acceleration signal may be overwhelmed by noise, and the equation is less sensitive to the change of mass, so the estimation result is unreliable. At this time, the EBS system returns to the accelerator pedal opening degree judgment process, and the cycle is repeated. Through the acceleration judgment, the small acceleration fluctuations caused by sensor noise, slight road fluctuations, etc. can be effectively filtered out to prevent false triggering and further improve the accuracy of subsequent vehicle load estimation.

[0052] The road slope parameter is obtained by indirect calculation or direct measurement. The indirect calculation method is as follows: first, the signal of the longitudinal acceleration sensor is obtained, and the ECU performs real-time backstepping based on the signal of the longitudinal acceleration sensor, the engine torque / driving force model, the vehicle mass (initial value or last estimated value), and a powerful longitudinal dynamics model. Then, the current driving force (F drive ) is calculated according to the engine torque, transmission ratio, etc., the air resistance (F air ) is calculated according to the vehicle speed, air resistance coefficient, etc., and the rolling resistance (F roll ) is calculated according to the known vehicle mass and rolling resistance coefficient. The above results and the measured acceleration (a measured ) are substituted into the following equation: F drive -F air -F roll =m*a measured +m*g*sin(θ); θ is the slope angle. Thus, the road slope value can be directly calculated. The direct measurement method can be detected by a high-precision inertial measurement unit (IMU). The IMU usually includes a three-axis accelerometer and a three-axis gyroscope. The three-axis accelerometer can sense the direction of the gravitational acceleration g. When the vehicle is parked on a slope, the gravitational vector measured by the three-axis accelerometer will be tilted relative to the vehicle coordinate axis. By analyzing this tilt angle, the slope can be directly obtained. During driving, the data of the gyroscope need to be combined to eliminate the interference of vehicle motion acceleration through Kalman filtering and other fusion algorithms to obtain an accurate slope value. This method is more direct and fast, but the cost is high.

[0053] The road slope is set as a single threshold, and the road slope threshold value can be set to 3% to 5%. Preferably, the road slope threshold value is set to 3%, and the road slope threshold value is recorded as the fifth threshold value.

[0054] The EBS system is configured to obtain the slope value of the current road shape of the vehicle, which includes the EBS system performing the slope value calculation process described above, which has been described in detail above and will not be repeated here. Then determine whether the current road slope value is less than the fifth threshold value, if the current road slope value is less than the fifth threshold value, it means that the road is "flat enough", at this time the gravity component force mg*sin(θ) is small enough to be ignored (cos(θ)≈1), which can be simplified to zero from the complex dynamics model, so as to use the flat road model for estimation, greatly simplify the calculation and ensure the accuracy, at this time the load estimation condition is met, at this time the EBS system performs the load estimation step; if the current road slope value is greater than or equal to the fifth threshold value, it means that the road slope is significant, at this time the gravity component force becomes a non-negligible disturbance term, if the flat road model is still used, a large error will be introduced, at this time the EBS system returns to the accelerator pedal opening degree determination step, and the cycle is repeated. By judging the road slope, the largest disturbance source of the slope is directly excluded, which fundamentally ensures the accuracy of the estimation result.

[0055] The signals generated by these sensors are transmitted to the relevant ECUs (such as EBS, engine ECU) through the CAN bus network to realize the load estimation algorithm of the present application.

[0056] The EBS system is also configured to perform a vehicle load estimation process. Specifically, the EBS system is configured to, in response to the current operating state of the vehicle meeting the load estimation triggering condition, calculate a plurality of theoretical accelerations corresponding to a plurality of assumed weights in the empty mass to full mass interval based on a vehicle dynamics model. Compare all theoretical accelerations with the measured acceleration, select the assumed weight with the smallest matching error from the plurality of assumed weights as the final load estimation value.

[0057] Further, the EBS system is also configured to: input each assumed weight in the empty mass to full mass interval into the vehicle dynamics model described by the following formula to obtain a plurality of theoretical accelerations , the formula is as follows:

[0058] ; is the current driving force of the vehicle; is the current air resistance of the vehicle; is the current rolling resistance of the vehicle; is the acceleration resistance coefficient;

[0059] Wherein, the calculation step of the current driving force of the vehicle includes: obtaining the current torque of the vehicle engine, calculating the current driving force of the vehicle according to the current torque according to the following formula: ​

[0060] ; is the transmission efficiency of the vehicle transmission system; is the total transmission ratio of the transmission system;

[0061] The calculation step of the current air resistance of the vehicle includes: obtaining the current driving speed of the vehicle , and calculating the current air resistance of the vehicle according to the current driving speed of the vehicle , according to the following formula:

[0062] ; is the air resistance coefficient; is the windward area of the vehicle;

[0063] The calculation step of the current rolling resistance of the vehicle includes: according to the assumed weight , the current rolling resistance of the vehicle is calculated according to the following formula:

[0064] ; is the acceleration of gravity; is the rolling resistance coefficient.

[0065] Further, the EBS system is also configured to: obtain the actual acceleration of the current vehicle, calculate the square error of each theoretical acceleration and actual acceleration respectively, determine the minimum square error from all the square errors, and take the multiple assumed weights corresponding to the minimum square error as the final load estimation value.

[0066] The load estimation method for the vehicle electronic brake system will be described below, and the electronic brake system (EBS) of the present application can perform any one of the load estimation methods for the vehicle electronic brake system described below.

[0067] As shown in Figure 1 , in some embodiments of the present application, a load estimation method for a vehicle electronic brake system is provided, comprising:

[0068] Step S110, based on the current operating parameters of the vehicle, determine whether the current operating state of the vehicle meets the preset load estimation triggering condition. Since there are many cases of vehicle operating state, in order to improve the accuracy of subsequent load estimation, the current operating state of the vehicle needs to be analyzed. When the vehicle is in the state of braking, non-low speed, straight driving, obvious acceleration and flat road conditions, the load estimation method is more accurate. Therefore, the operating state of the vehicle needs to be determined first.

[0069] ​​Step S110, the step of confirming whether the current running state of the vehicle meets the preset load estimation triggering condition based on the current running parameters of the vehicle, comprises:

[0070] Step S111, obtaining the current running parameters of the vehicle.

[0071] The running parameters include the accelerator pedal opening degree, the vehicle speed, the steering wheel turning angle, the vehicle acceleration and the road slope.

[0072] The vehicle electronic braking system comprises an accelerator pedal position sensor, which is used to detect the accelerator pedal opening degree of the current vehicle, and determine whether the current vehicle is in a braking state or a non-braking state through the accelerator pedal opening degree. The accelerator pedal position sensor is configured to start detecting the accelerator pedal opening degree information and uploading the detected accelerator pedal opening degree information to the vehicle electronic braking system in response to a change in the accelerator pedal opening degree.

[0073] The vehicle electronic braking system further comprises a wheel speed sensor, which is used to detect the rotation speed of the vehicle wheel during the current driving of the vehicle, and determine whether the current vehicle is in a low-speed state or a non-low-speed state through the wheel rotation speed. The wheel speed sensor is configured to start obtaining the wheel rotation speed information of the current vehicle driving and uploading the wheel rotation speed information to the vehicle electronic braking system in response to a change in the accelerator pedal opening degree.

[0074] The vehicle electronic braking system further comprises a steering wheel turning angle sensor, which is used to detect the turning angle of the steering wheel during the current driving of the vehicle, and determine whether the vehicle is driving in a straight line or a curve through the steering wheel turning angle. The steering wheel turning angle sensor is configured to start obtaining the turning angle information of the steering wheel during the current driving of the vehicle and uploading the turning angle information of the steering wheel to the vehicle electronic braking system in response to a change in the accelerator pedal opening degree.

[0075] The vehicle electronic braking system further comprises an acceleration sensor, which is used to detect the acceleration of the current driving of the vehicle, and determine whether the vehicle is driving at a constant speed / low deceleration or obvious acceleration through the acceleration. The acceleration sensor is configured to start obtaining the acceleration information of the current driving of the vehicle and uploading the acceleration information to the vehicle electronic braking system in response to a change in the accelerator pedal opening degree.

[0076] The vehicle electronic braking system further comprises an acceleration sensor, which is used to detect the acceleration of the current driving of the vehicle, and determine whether the vehicle is driving at a constant speed / low deceleration or obvious acceleration through the acceleration. The acceleration sensor is configured to start obtaining the acceleration information of the current driving of the vehicle and uploading the acceleration information to the vehicle electronic braking system in response to a change in the accelerator pedal opening degree.

[0077] The vehicle electronic braking system further comprises an inertial measurement unit configured to detect a slope state of a current driving road of the vehicle, and determine whether the vehicle is driving on a flat road or a significant slope road according to the slope state of the road. The inertial measurement unit is configured to, in response to a change in the accelerator pedal opening degree, start to acquire the slope information of the road on which the vehicle is currently driving, and upload the slope information of the road to the vehicle electronic braking system.

[0078] In some embodiments, the step of acquiring the current operating parameter of the vehicle comprises a step of calculating a road slope value. The acceleration information of the vehicle operating acceleration detected by the longitudinal acceleration sensor is acquired, and based on the acceleration information, an engine torque / driving force model, and a vehicle mass (an initial value or a last estimated value), a longitudinal dynamics model is real-time backstepping, and a current driving force (F drive ) is calculated according to the engine torque, the transmission ratio, etc., an air resistance (F air ) is calculated according to the vehicle speed, the air resistance coefficient, etc., a rolling resistance (F roll ) is calculated according to the known vehicle mass and the rolling resistance coefficient, and the above results and the measured acceleration (a measured ) are substituted into the following equation: F drive -F air -F roll =m*a measured +m*g*sin(θ); and a slope angle value θ is calculated.

[0079] In step S112, the current operating state of the vehicle is determined according to the current operating parameter of the vehicle.

[0080] The vehicle operating state includes a braking state, a non-braking state, an acceleration state, a deceleration state, a constant speed state, a straight driving state, a curve driving state, and a slope state of a driving road.

[0081] In some embodiments, the vehicle operating state is determined as follows:

[0082] It is determined whether the accelerator pedal opening degree is greater than a first threshold value. If the accelerator pedal opening degree is greater than the first threshold value, the vehicle is currently in a non-braking state. If the accelerator pedal opening degree is less than the first threshold value, it indicates that the driver is in a coasting, idling or braking state, which does not meet the estimation condition. In this case, the determination of the accelerator pedal opening degree is restarted every predetermined time interval, which can be set to 3 to 5 seconds, and the cycle is repeated.

[0083] The first threshold value can be set to 2% to 5% of the accelerator pedal opening degree, and preferably, the first threshold value is set to 2%.

[0084] If the vehicle speed is greater than the second threshold value, the vehicle is currently in a non-low-speed state; if the vehicle speed is less than the second threshold value, the vehicle is in a low-speed or stationary state, at which time the signal noise is large and the calculation is inaccurate, and the system does not estimate, at which time the accelerator pedal opening degree detection / judgment step is returned to, and the accelerator pedal opening degree detection / judgment is re-performed, and the cycle is repeated.

[0085] The second threshold value can be set to 5 km / h to 10 km / h. Preferably, the second threshold value is set to 5 km / h.

[0086] If the absolute value of the steering wheel angle is less than the third threshold value, the vehicle is currently in a straight-line driving state; if the absolute value of the current steering wheel angle is greater than or equal to the third threshold value, the vehicle is currently turning, at which time the lateral dynamics of the vehicle becomes complex, and centrifugal force, left and right wheel load transfer and other factors will seriously interfere with the estimation accuracy based on the longitudinal dynamics model, at which time the system load estimation result accuracy is poor, at which time the accelerator pedal opening degree judgment step is returned to, and the cycle is repeated.

[0087] The third threshold value can be set to 3° to 5°. Preferably, the third threshold value is set to 5°.

[0088] If the vehicle acceleration is greater than the fourth threshold value, the vehicle is currently in an acceleration state; if the current vehicle acceleration is less than or equal to the fourth threshold value, the vehicle is in a constant speed or small deceleration state, at which time the acceleration signal can be drowned by noise, and the equation has low sensitivity to mass change, and the estimation result is unreliable, at which time the accelerator pedal opening degree judgment process is returned to, and the cycle is repeated.

[0089] The fourth threshold value can be set to 0.1 m / s² to 0.3 m / s². Preferably, the fourth threshold value can be set to 0.1 m / s².

[0090] If the absolute value of the road slope is less than the fifth threshold value, the vehicle is currently driving on a non-ramp road; if the current road slope value is greater than or equal to the fifth threshold value, the road slope is significant, at which time the gravity component becomes a non-negligible disturbance term, and if the flat road model is still used, a large error will be introduced, at which time the accelerator pedal opening degree judgment step is returned to, and the cycle is repeated.

[0091] The fifth threshold value can be set to 3% to 5%. Preferably, the fifth threshold value is set to 3%.

[0092] In other embodiments, the vehicle operating state confirmation method is as follows:

[0093] If the current accelerator pedal opening is less than the first pedal threshold, the current accelerator pedal opening is re-acquired, and the process is repeated. If the current accelerator pedal opening is greater than the first pedal threshold, the vehicle is in a non-braking state. At this time, it is determined whether the current accelerator pedal opening is greater than the second pedal threshold. If it is greater, the vehicle is accelerating rapidly or under heavy load. If the current accelerator pedal opening is less than the second pedal threshold, the current accelerator pedal opening is continuously acquired, and it is determined whether the current accelerator pedal opening is greater than the second pedal threshold. The process is repeated. The first pedal threshold is lower than the second pedal threshold.

[0094] The accelerator pedal threshold of the embodiment is set to a double threshold, which is a low threshold and a high threshold, i.e., the first pedal threshold and the second pedal threshold. By comparing the current accelerator pedal opening with the first pedal threshold, it is determined that the current running state of the vehicle is a braking state or a non-braking state. Then, the current accelerator pedal opening is compared with the second pedal threshold to determine whether the vehicle is in a significant acceleration state. Therefore, only the subsequent steering wheel angle and road slope determination is required at this time, and the subsequent vehicle speed and acceleration determination is not required, thereby simplifying the triggering of the vehicle load estimation step. The steering wheel angle and road slope determination steps have been described in detail above, and will not be described here.

[0095] The first pedal threshold can be set to 3% to 5%. Preferably, the first pedal threshold is set to 3%. The second pedal threshold can be set to 30% to 35%. Preferably, the second pedal threshold is set to 30%.

[0096] In some specific embodiments, the vehicle running state confirmation method is as follows:

[0097] It is determined whether the accelerator pedal opening increases from below the third pedal threshold to above the third pedal threshold. When the accelerator pedal opening increases from below the third pedal threshold to above the third pedal threshold, the vehicle is in a non-braking state. At this time, the current accelerator pedal opening is continuously acquired, and it is determined whether the accelerator pedal opening falls below the fourth pedal threshold. When the accelerator pedal opening falls below the fourth pedal threshold, the vehicle is in a braking state, and the subsequent steps are not required. That is, the system stops subsequent determination or load estimation, and returns to the accelerator pedal determination step, and the process is repeated.

[0098] The acceleration pedal threshold of the embodiment is set as a double threshold, and the double threshold is an opening threshold and a closing threshold, that is, a third pedal threshold and a fourth pedal threshold. The current acceleration pedal opening degree change is compared with the third pedal threshold to determine whether the current running state of the vehicle is a braking state or a non-braking state. When the vehicle is in a non-braking state, subsequent vehicle speed, steering wheel angle, acceleration, and road slope are judged. Meanwhile, the current acceleration pedal opening degree change is compared with the fourth pedal threshold to determine whether the vehicle is currently in a braking state or a non-braining state. When the vehicle is currently in a braking state, it means that the vehicle has stopped or is close to a stopped state. At this time, whether in the steps of judging the vehicle speed, steering wheel angle, acceleration, and road slope or in the step of estimating the vehicle load, the vehicle should be stopped and the acceleration pedal judgment step should be performed again. The subsequent vehicle speed, steering wheel angle, acceleration, and road slope judgment steps are consistent with the vehicle speed, steering wheel angle, acceleration, and road slope judgment steps described above. The detailed process of the above steps has been described in detail above, and will not be repeated here.

[0099] The first pedal threshold can be set to 2% to 5%, and preferably, the first pedal threshold is set to 3%. The second pedal threshold can be set to 1.5% to 3%, and preferably, the second pedal threshold is set to 1.5%.

[0100] In step S113, it is determined whether the preset load estimation triggering condition is met according to the current running state of the vehicle. The preset load estimation triggering condition is that the vehicle is currently in a non-braking, straight-line driving, obvious acceleration driving, and non-slope road driving state.

[0101] Specifically, whether the preset load estimation triggering condition is met is executed in the following logical steps in sequence. Only when the conditions of all steps, i.e., steps S1131 to S1135, are met, it is determined that the triggering condition is met.

[0102] In step S1131, in response to the vehicle being currently in a non-braking state, it is determined whether the vehicle is currently in a non-low-speed state driving. The step of determining whether the vehicle is currently in a non-low-speed state driving has been determined in step S112, and will not be repeated here.

[0103] In step S1132, in response to the vehicle being currently in a non-low-speed state driving, it is determined whether the vehicle is currently in a straight-line driving state. The step of determining whether the vehicle is currently in a straight-line driving state has been determined in step S112, and will not be repeated here.

[0104] In step S1133, in response to the vehicle being currently in a straight-line driving state, it is determined whether the vehicle is currently in an acceleration driving state. The step of determining whether the vehicle is currently in an acceleration driving state has been determined in step S112, and will not be repeated here.

[0105] Step S1134, in response to the current driving state of the vehicle is acceleration, then determine whether the current driving road condition of the vehicle is non-ramp state. Wherein, the step of determining whether the current driving road condition of the vehicle is non-ramp state has been determined in step S112, and will not be repeated here.

[0106] Step S1135, in response to the current driving road condition of the vehicle is non-ramp state, then the load estimation trigger condition is met.

[0107] Step S120, if met, based on the vehicle dynamics model, the theoretical acceleration corresponding to multiple hypothetical weights in the empty mass to full mass interval is calculated respectively.

[0108] First, the current driving force of the vehicle is calculated , the current air resistance of the vehicle and the current rolling resistance of the vehicle , the process is as follows:

[0109] The current driving force of the vehicle is calculated : the current torque of the vehicle engine is obtained , according to the current torque , the current driving force of the vehicle is calculated according to the following formula :

[0110] ;

[0111] Wherein, is the transmission efficiency of the vehicle transmission system; is the total transmission ratio of the transmission system.

[0112] The current air resistance of the vehicle is calculated : the current driving speed of the vehicle is obtained , according to the current driving speed of the vehicle , the current air resistance of the vehicle is calculated according to the following formula :

[0113] ;

[0114] Wherein, is the air resistance coefficient; is the windward area of the vehicle.

[0115] The current rolling resistance of the vehicle is calculated : according to the hypothetical weight , the current rolling resistance of the vehicle is calculated according to the following formula :

[0116] ;

[0117] wherein, is the gravitational acceleration; is the rolling resistance coefficient.

[0118] The step of calculating the theoretical acceleration corresponding to each of the plurality of assumed weights in the empty mass to full mass range based on the vehicle dynamics model comprises:

[0119] The empty mass to full mass range is divided into a plurality of assumed weights, and each of the plurality of assumed weights is denoted as m i (i = 1, 2, 3, …, n). The plurality of theoretical accelerations are obtained by substituting the plurality of assumed weights into the vehicle dynamics model as follows: The vehicle dynamics model is as follows:

[0120] ;

[0121] wherein, is the current driving force of the vehicle; is the current air resistance of the vehicle; is the current rolling resistance of the vehicle; is the acceleration resistance coefficient.

[0122] The step 120 of calculating the theoretical acceleration corresponding to each of the plurality of assumed weights in the empty mass to full mass range further comprises:

[0123] In step 121, the assumed mass is taken as the traversal object to traverse the mass traversal table. The mass traversal table records at least each of the assumed mass values in the empty mass to full mass range. The mass traversal table is configured by the operator according to the actual situation of the vehicle when the vehicle is delivered from the factory, and will not be described here.

[0124] In step 122, the theoretical acceleration is calculated according to the vehicle dynamics model for each of the assumed masses after traversal, and each of the theoretical accelerations is associated with the corresponding assumed mass.

[0125] In step S130, all of the theoretical accelerations are compared with the measured acceleration, and the assumed mass with the minimum matching error of the measured acceleration is selected from the plurality of assumed masses as the final load estimation value.

[0126] In step S131, the actual acceleration of the current vehicle is obtained.

[0127] In step S132, the square error of each of the theoretical acceleration and the actual acceleration is calculated respectively.

[0128] In step S133, the minimum square error is determined from all of the square errors.

[0129] Step S134, the assumed weight corresponding to the minimum square error is taken as the final load estimation value. In step S122, each theoretical acceleration is associated with the corresponding assumed mass, and here the theoretical acceleration corresponding to the minimum square error is matched to find the assumed weight associated with the theoretical acceleration, which is taken as the final load estimation value.

[0130] In other embodiments of the present application, a computer is also provided, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the relevant steps of the load estimation method for a vehicle electronic braking system described above when executing the computer program. The processor implements the load estimation method for a vehicle electronic braking system described above when executing the computer program.

[0131] In other embodiments of the present application, a computer readable storage medium is also provided, which stores a computer program, and the computer program implements the load estimation method for a vehicle electronic braking system described above when executed by a processor. The computer program implements the load estimation method for a vehicle electronic braking system described above when executed by the processor.

[0132] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiments can be completed by a computer program instructing related hardware, and the computer program can be stored in a non-volatile computer readable storage medium. When executed, the computer program can include the processes of the above-mentioned embodiments. Any reference to memory, storage, prediction model or other medium used in the embodiments provided in the present application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration but not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0133] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above functional units and modules is taken as an example, and in actual application, the above functions can be completed by different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the above described functions.

[0134] The skilled in the art can understand that the present application confirms the estimated triggering condition of stable acceleration of the vehicle by judging the parameters such as the accelerator pedal opening, the vehicle speed, the steering wheel angle, the acceleration and the road slope condition, then calculates the theoretical acceleration corresponding to all assumed weights in the empty-to-full load mass interval in parallel, finally selects the solution with the minimum error as the load result by matching the theoretical acceleration with the measured value, effectively overcomes the excessive dependence on ideal working conditions of the traditional method, significantly improves the real-time and accuracy of load estimation, and further improves the precision of adaptive brake force regulation of the electronic brake system.

[0135] The skilled in the art can understand that the modules in the device in the embodiments can be adaptively changed and arranged in one or more devices different from the embodiments. The modules or units or components in the embodiments can be combined into one module or unit or component, and furthermore can be divided into multiple sub-modules or sub-units or sub-components. Except that at least some of such features and / or processes or units are mutually exclusive, all features disclosed in the specification (including the accompanying claims, abstract and drawings) and all processes or units of any method or device disclosed thus can be combined in any combination. Unless explicitly stated otherwise, each feature disclosed in the specification (including the accompanying claims, abstract and drawings) can be replaced by an alternative feature providing the same, equivalent or similar purpose.

[0136] In addition, the skilled in the art can understand that although some embodiments herein include certain features instead of others included in other embodiments, the combination of features of different embodiments means to be within the scope of the present application and form different embodiments. For example, in the claims, any of the claimed embodiments can be used in any combination.

[0137] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed with the preferred embodiments as above, it is not intended to limit the present application, and any person skilled in the art can make some changes or modifications to the above-mentioned technical content with the above-mentioned prompt without departing from the technical solution of the present application, and the equivalent embodiments of equivalent changes can be made. The embodiments in the above-mentioned embodiments can be further combined or replaced, as long as they do not deviate from the technical solution of the present application. Any simple modification, equivalent change and modification made to the above-mentioned embodiments according to the technical essence of the present application still belongs to the scope of the present application.

Claims

1. A load estimation method for a vehicle electronic braking system, characterized in that, include: Based on the vehicle's current operating parameters, confirm whether the vehicle's current operating status meets the preset load estimation trigger conditions; The operating parameters include accelerator pedal opening, vehicle speed, steering wheel angle, vehicle acceleration, and road gradient; If satisfied, then based on the vehicle dynamics model, calculate the theoretical acceleration corresponding to multiple assumed weights in the range from unloaded to fully loaded mass. All theoretical accelerations are compared with measured accelerations, and the hypothetical weight with the smallest matching error with the measured acceleration is selected from the multiple hypothetical weights as the final load estimate.

2. The load estimation method according to claim 1, characterized in that, The step of confirming whether the current operating state of the vehicle meets the preset load estimation triggering conditions based on the current operating parameters of the vehicle includes: Obtain the vehicle's current operating parameters; Based on the vehicle's current operating parameters, determine the vehicle's current operating status; Based on the current operating status of the vehicle, confirm whether the preset load estimation trigger condition is met; The operating states include braking state, non-braking state, acceleration state, deceleration state, constant speed state, straight driving state, curve driving state, and the slope of the driving road.

3. The load estimation method according to claim 2, characterized in that, The confirmation of whether the preset load estimation trigger condition is met is achieved by executing the following logical steps in sequence. The trigger condition is confirmed to be met only if all the conditions in all steps are met: In response to the vehicle being in a non-braking state, it is determined whether the vehicle is currently traveling at a non-low speed. If the vehicle is not currently traveling at a low speed, determine whether the vehicle is currently traveling in a straight line. In response to the fact that the vehicle is currently traveling in a straight line, it is determined whether the vehicle is currently accelerating. If the vehicle is currently accelerating, determine whether the current road condition is not a slope. If the vehicle is currently traveling on a non-slope road, then the load estimation trigger condition is met.

4. The load estimation method according to claim 3, characterized in that, The step of determining the current operating status of the vehicle based on the vehicle's current operating parameters includes: Determine if the accelerator pedal opening is greater than the first threshold. If the accelerator pedal opening is greater than the first threshold, the vehicle is currently in a non-braking state. Determine if the vehicle speed exceeds the second threshold; If the vehicle speed is greater than the second threshold, the vehicle is currently not traveling at low speed. Determine if the absolute value of the steering wheel angle is less than the third threshold; If the absolute value of the steering wheel angle is less than the third threshold, then the vehicle is currently in a straight-line driving state; Determine if the vehicle's acceleration exceeds the fourth threshold; If the vehicle's acceleration exceeds the fourth threshold, the vehicle is currently accelerating; and, Determine whether the absolute value of the road slope is less than the fifth threshold; If the absolute value of the road gradient is less than the fifth threshold, then the vehicle is currently traveling on a non-slope road.

5. The load estimation method according to claim 1, characterized in that, The steps for calculating the theoretical acceleration corresponding to multiple assumed weights within the range of empty to fully loaded mass based on the vehicle dynamics model include: Each hypothetical weight within the range from unloaded mass to fully loaded mass Substituting the vehicle dynamics model described in the following formula yields multiple theoretical accelerations. The formula is as follows: ； in, The current driving force of the vehicle; The vehicle's current air resistance; This represents the vehicle's current rolling resistance. This is the acceleration drag coefficient.

6. The load estimation method according to claim 5, characterized in that, The calculation steps for the vehicle's current driving force include: Get the current engine torque of the vehicle Based on the current torque Calculate the vehicle's current driving force using the following formula. : ； in, The transmission efficiency of the vehicle's transmission system; This represents the total transmission ratio of the transmission system.

7. The load estimation method according to claim 2, characterized in that, The steps for calculating the vehicle's current air resistance include: Get the vehicle's current speed Based on the vehicle's current speed Calculate the vehicle's current air resistance using the following formula. : ； in, This refers to the air drag coefficient; This refers to the vehicle's frontal area.

8. The load estimation method according to claim 5, characterized in that, The calculation steps for the current rolling resistance of the vehicle include: Based on the assumed weight The current rolling resistance of the vehicle is calculated using the following formula. : ； in, It is the acceleration due to gravity; This is the rolling resistance coefficient.

9. The load estimation method according to claim 5, characterized in that, The step of comparing all the theoretical accelerations with the measured accelerations and selecting the hypothetical weight with the smallest matching error with the measured acceleration from the plurality of hypothetical weights as the final load estimate includes: Obtain the current vehicle's actual acceleration; Calculate the squared error between each theoretical acceleration and the actual acceleration; Determine the least squared error from all the squared errors; The assumed weights corresponding to the least square error are used as the final load estimate.

10. An electronic braking system (EBS), characterized in that, Includes a load estimation method for a vehicle electronic braking system as described in any one of claims 1 to 9.

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