Method for estimating actual running resistance of vehicle

Abstract

The present application relates to a kind of vehicle actual driving resistance estimation method, it is characterized in that: vehicle is based on actual road normal driving, through vehicle bus, external instrument or vehicle built-in sensor, the speed of vehicle when driving, engine speed, torque, friction torque, throttle opening, gear and injection signal information are collected;Using GPS, gyroscope and accelerometer, or using vehicle built-in inertial navigation system to collect speed, acceleration, slope, direction angle information, based on these data, estimate actual road resistance curve coefficient value, further combined with slope resistance and acceleration resistance calculation, estimate actual road resistance.The beneficial effect: the present application is suitable for all real scene needs to calculate the need of vehicle actual road resistance, improves test efficiency;The result obtained represents the actual road resistance of the time condition, can better meet the test demand;Based on existing vehicle technology, it can realize the estimation and prediction of road driving resistance.

Description

Technical Field

[0001] This invention belongs to the field of automotive testing technology, and in particular relates to a method for estimating the actual driving resistance of a vehicle. Background Technology

[0002] Chassis dynamometer testing is a commonly used method in modern automotive product design, development, and performance evaluation for evaluating vehicle performance, including assessing power, fuel consumption, and emissions. By controlling test conditions, the chassis dynamometer can accurately simulate the actual driving resistance of a vehicle, enabling experimental testing. Before simulating road driving resistance, the vehicle's road resistance curve must be determined to set the chassis dynamometer parameters. Because the empirical values ​​recommended by regulations and standards generally differ significantly from actual values, experimental methods are often used to obtain the relationship curve between the vehicle's actual resistance and speed. Specifically, the vehicle's resistance value can be obtained by referring to a table based on the coasting resistance curve using the vehicle speed.

[0003] Currently, the standard methods for testing vehicle driving resistance mostly adopt the coasting method (as stipulated in standards such as GB18352-2016 and GB / T27840-2021). Simply put, under favorable weather conditions (a certain temperature and humidity range, and wind speeds insufficient to interfere with the test results), the car accelerates to a specified speed on a dedicated, straight test track, then the transmission is placed in neutral and coasts to a low speed or even 0 speed. A data acquisition system with GPS positioning is used to synchronously record the data throughout the coasting process. The quadratic function relationship between the vehicle's resistance and speed during coasting is obtained through standard calculation methods, i.e., F = A + B·V + C·V. 2 The relationship is given by F, where F is the sliding resistance, V is the vehicle speed, and A, B, and C are the drag coefficients.

[0004] This method can obtain relatively accurate vehicle drag curves and is suitable for standard laboratory regulatory testing, but it has certain limitations. Firstly, because it involves specific test vehicles, fixed loads, and coasting tests conducted under specific test conditions and temperatures, the coasting drag curve cannot represent coasting drag under other conditions. This is because variations in road conditions, altitude, load, temperature, and vehicle condition in real-world scenarios will all correspond to a specific drag curve. It is impractical to use the testing methods required by the above regulations to obtain coasting drag curves for all other conditions. Only approximate values ​​can be obtained through empirical parameter corrections, such as temperature and altitude corrections to the coasting drag curve, but these corrections may have large errors or be impossible to correct. Therefore, for development testing needs that require obtaining actual road coasting drag curves, the technology and methods are currently insufficient.

[0005] With the development of vehicle technology, model-based vehicle energy-saving control technology needs to realize intelligent control of the power system based on actual resistance characteristics. If the actual road sliding resistance curve can be obtained, it is also a solution for real-time vehicle traction prediction. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the above-mentioned technologies and provide a method for estimating the actual driving resistance of a vehicle. This method can be used for estimating and identifying the actual road resistance curve, as well as for predicting the actual road driving traction force required by the vehicle model control strategy.

[0007] To achieve the above objectives, this invention employs the following technical solution: a method for estimating the actual driving resistance of a vehicle. Its characteristics are: based on normal driving on actual roads, the vehicle collects information such as vehicle speed, engine speed, torque, friction torque, throttle opening, gear position, and fuel injection signal through vehicle bus, external instruments, or built-in vehicle sensors; using GPS, gyroscopes, and accelerometers, or utilizing the vehicle's built-in inertial navigation system, it collects information on vehicle speed, acceleration, gradient, and steering angle. Based on this data, the actual road resistance curve coefficient value is estimated. Furthermore, by combining gradient resistance and acceleration resistance calculations, the actual road resistance can be estimated. The specific steps are as follows:

[0008] Step 1: Determine traffic conditions, weather conditions, and road conditions to meet the vehicle operating environment conditions for data collection as described in this invention.

[0009] Step 2: Determine the vehicle's preheating status: Select a vehicle operating at medium to high speed to ensure it reaches the preheating requirements, and that the vehicle's coolant and engine oil temperatures stabilize.

[0010] Step 3, Driving Requirements: Select a relatively straight actual road and drive the vehicle with relatively stable driving behavior. Avoid sudden acceleration, deceleration, and rapid steering wheel adjustments (such as frequent lane changes and turns) as much as possible. Record the necessary vehicle operation data in real time. Data from sudden acceleration, deceleration, braking, gear shifting, and steering actions must be discarded and not used in subsequent calculations.

[0011] Step 4: Data Acquisition. During vehicle operation, relevant data is collected at a frequency of at least 1Hz. This data is acquired via the CAN bus of the vehicle's OBD port, including vehicle speed V, engine speed n, and engine torque T. tq Engine friction torque T m The system collects information on throttle opening, gear position, and fuel injection signals; it also collects vehicle speed, acceleration a, slope θ or i, and steering angle information using GPS, gyroscope, and accelerometer; and selects either the "constant speed driving method" or the "actual driving speed segment extraction method" described in this invention to complete data collection.

[0012] Step 5: Parameter Estimation. Based on the test data obtained in Step 4, data filtering, processing, and calculation are performed to obtain estimated values ​​of the resistance curve coefficients for the vehicle on actual roads.

[0013] Furthermore, the judgment of traffic conditions, weather conditions, and road conditions in step one is as follows: it shall be carried out under the conditions of no rain, snow, or fog, and is applicable to temperatures of -20 to 40°C, relative humidity of <95%, and altitudes below 5000m; road traffic index ≤2; wind speed ≤2, average ground wind speed ≤3m / s, and gusts not greater than 5m / s.

[0014] Furthermore, step four involves the acquisition and calculation of actual vehicle operating data. Let F... t T represents the driving force of a vehicle. tq Indicates engine torque, i g Let i0 represent the gear ratio of the transmission, i0 represent the gear ratio of the final drive, η represent the mechanical efficiency of the transmission system, and r be the wheel radius. Then the driving force F t for:

[0015]

[0016] If the vehicle is coasting in gear, the engine stops injecting fuel and is in a dragging state, the engine torque T tq If the value is negative, let it be T. m Then the driving force F t for:

[0017]

[0018] Among them, engine torque T tq and reverse torque T m The transmission ratio i is obtained and recorded in real time from the vehicle's CAN bus information. g The transmission ratio i0 of the main reducer is obtained through vehicle CAN bus information; the wheel radius r is selected as the static radius value of the wheel.

[0019] The relationship between engine speed and vehicle speed is as follows:

[0020]

[0021] Where V is the vehicle's speed, obtained in real time from GPS or CAN bus information; n is the engine speed, obtained in real time from CAN bus information; and F is the vehicle's driving force. t The relationship between engine speed, torque, and vehicle speed is as follows:

[0022]

[0023] If the vehicle is in a coasting, reverse motion with gear engaged, the formula is:

[0024]

[0025] When a car travels at a constant speed on a level road, it needs to overcome rolling resistance from the ground and air resistance from the air; let the rolling resistance be F. f Air resistance is F w The slope resistance when a vehicle travels uphill is F. i When a vehicle accelerates, it also needs to overcome the acceleration resistance F. j The driving force Ft of the vehicle is the sum of all resistance forces, that is:

[0026] F t =F f +F w +F i +F j

[0027] Among them, “F f +F w "A + B·V + C·V is a quadratic function of the vehicle's speed, which is the quadratic function of the standard coasting method." 2 The resistance value determined by the values ​​A, B, and C in the text;

[0028] ramp resistance F i The gradient is the component of a vehicle's weight along a slope when it is traveling on an incline. Under normal circumstances, the gradient of most roads is relatively small. For example, according to my country's highway route design specifications, the maximum longitudinal slope of expressways in plains and hilly areas is 3%, and the slope of Class IV highways in mountainous and hilly areas is 9%. Road gradient is expressed as the ratio of slope height h (in meters) to base length s (in meters), that is:

[0029] Therefore, if the slope of the road is small, sinθ≈tanθ=i, then:

[0030] F i =M·g·sinθ

[0031] Where M is the vehicle mass (in kg), and g is the acceleration due to gravity (9.8 m / s²). 2 ); θ is the longitudinal slope angle of the road; if the road is basically straight, F i The value is approximately 0.

[0032] Acceleration resistance F j This is the inertial force that overcomes the acceleration of a vehicle's mass. A car's mass is divided into translational mass and rotational mass. When a car accelerates, the translational mass generates inertial force, while the rotational mass generates inertial torque.

[0033]

[0034] Where, m r Rotational mass refers to the equivalent effective mass (unit: kg) of all rotating parts and wheels of a vehicle when it is traveling in neutral on a road. r It can be estimated based on 3% of the vehicle's baseline mass. The vehicle's acceleration a (unit: m / s²) 2 From the above formula, we can derive:

[0035] F t =(A+B·V+C·V) 2 )+M·g·sinθ+(M+m r )·a, combined with the above F t The calculation formula further yields:

[0036]

[0037] Right now:

[0038]

[0039] Or, when coasting in gear:

[0040]

[0041] Furthermore, the constant speed driving method described in step four, under relatively straight road conditions and good traffic conditions, is preferentially selected as the method for determining the vehicle's resistance coefficients A, B, and C. In this case, the slope resistance Fi and acceleration resistance F... j It can be approximated as 0. The highest test speed is selected based on the actual road speed limit and the vehicle's maximum speed limit. The speed is gradually reduced from high speed to low speed, with a speed change of no more than 20 km / h, until the speed is below 20 km / h. To ensure effective fitting of the resistance curve, at least 5 speed points are required for test data. At each speed point, the speed is kept stable for a period of time to obtain sufficient data. The calculation data is selected based on the stage where the speed is basically stable and the driver does not make sudden acceleration, deceleration, braking, gear shifting, or significant steering wheel adjustments. According to formula (1), the quadratic function relationship between driving resistance and vehicle speed V is obtained. The values ​​of A, B, and C are obtained by analyzing the least squares regression method.

[0042] Further, the actual driving speed segment extraction method described in step four: On a test target road section, the vehicle is driven normally according to actual traffic conditions, and the driving speed covers as much as possible the normal driving speed range below the vehicle speed limit, avoiding driving behaviors such as sudden acceleration, sudden deceleration, and large steering wheel adjustments. The actual calculation data selection and the selected calculation formula are determined based on the collected data. Data with relatively stable operation and no large steering wheel adjustments, braking, or gear shifting behaviors are selected, and data with a speed below 15km / h are eliminated. If a coasting state occurs, formula (2) is selected; otherwise, formula (1) is selected, and the second-by-second quadratic function relationship between driving resistance and vehicle speed V is obtained. Based on the least squares regression method, the values ​​of A, B, and C are analyzed and obtained.

[0043] Once the values ​​of A, B, and C are determined, if the vehicle has a built-in inertial navigation system, the slope information of the driving road can be obtained in real time during the actual control of the vehicle. Furthermore, the road geographic information can also be obtained through the Internet of Vehicles. The vehicle can know the slope value of the route ahead in advance, and the actual road resistance can be estimated according to formula (1), thereby predicting the power demand and providing a solution for predictive control of the vehicle.

[0044] Beneficial effects: Compared with the prior art, the present invention 1) is applicable to all real-world scenarios requiring the calculation of actual road resistance of vehicles, and can be performed anytime and anywhere without the need for a dedicated test site, saving test costs and improving test efficiency; 2) the method is flexible and simple, and can be repeated multiple times as needed, and the results obtained represent the actual road resistance under the conditions at that time, rather than empirical correction values, which can better meet test requirements; 3) based on existing vehicle technology, without increasing hardware costs, the method of the present invention can realize the estimation and prediction of road driving resistance in the model-based control strategy of vehicles, meeting the technical requirements of vehicle traction predictive control. Attached Figure Description

[0045] Figure 1 The overall flowchart of the method described in this invention.

[0046] Figure 2 This is a flowchart of the implementation of method 1 for estimating vehicle driving resistance.

[0047] Figure 3 This is a flowchart of the implementation of method 2 for estimating vehicle driving resistance.

[0048] Figure 4 This is a speed distribution diagram of the test sampling points in a specific embodiment.

[0049] Figure 5 (a) is a graph showing the corresponding data of actual driving resistance and vehicle speed.

[0050] Figure 5(b) Fitting results of driving resistance curve in specific embodiments. Detailed Implementation

[0051] The specific implementation of the present invention will now be described in detail with reference to preferred embodiments.

[0052] As shown in the attached diagram, this embodiment provides a method for estimating the actual driving resistance of a vehicle. The vehicle is driven normally on actual roads. Information such as vehicle speed, engine speed, torque, friction torque, throttle opening, gear position, and fuel injection signal are collected via vehicle bus, external instruments, or built-in sensors. Information on vehicle speed, acceleration, gradient, and steering angle is collected using GPS, gyroscopes, and accelerometers, or by utilizing the vehicle's built-in inertial navigation system. Based on this data, the actual road resistance curve coefficient value is estimated. Further calculations can be made by combining gradient resistance and acceleration resistance to estimate the actual road resistance. The specific steps are as follows:

[0053] Step 1: Assess traffic conditions, weather conditions, and road conditions.

[0054] Because this method tests actual road resistance curves, it cannot be performed under extreme weather conditions or congested traffic. The method requires favorable weather conditions (no rain, snow, or fog) and is applicable to general temperature and humidity conditions (e.g., -20–40℃, <95% relative humidity) and altitude ranges (below 5000m). Road traffic must be smooth, with a traffic index not exceeding 2. To minimize the impact of wind speed on resistance calculations, wind speeds should be as low as possible; a wind speed not exceeding level 2 (light breeze) is recommended. Generally, the average ground wind speed should not exceed 3 m / s, and gusts should not exceed 5 m / s. If traffic is smooth and the road is straight, allowing for relatively constant speed driving, the "constant speed method" should be prioritized.

[0055] Step 2: Determine the vehicle's preheating status. The vehicle's coolant and engine oil temperatures should have reached a stable state. If the preheating is inadequate, consider operating the vehicle at medium to high speeds to allow it to reach the required preheating level.

[0056] Step 3: Driving Requirements. Choose either Method 1 or Method 2 below to complete data collection. Generally, choose a relatively straight actual road and drive the vehicle with relatively stable driving behavior. Try to avoid sudden acceleration, deceleration, and rapid steering wheel adjustments (such as frequent lane changes and turns). Record the required vehicle operation data in real time. Data from sudden acceleration, deceleration, braking, gear shifting, and large steering wheel adjustments will be excluded from subsequent calculations.

[0057] Method 1: Constant Speed ​​Driving Method. This method is relatively simple to calculate and is preferred for determining vehicle drag coefficients A, B, and C if relatively straight road conditions and traffic conditions are ideal. Select the highest test speed based on the actual road speed limit and the vehicle's maximum speed limit. Gradually change the speed from high to low (or low to high) in increments not exceeding 20 km / h until it drops below 20 km / h. At each speed point, maintain a stable speed for a period to ensure sufficient data acquisition. If continuous speed variation is not possible, select the appropriate speed based on actual conditions and gradually collect data at different speed points.

[0058] Method 2: Actual Driving Speed ​​Segment Extraction Method. If the road and traffic conditions described in Method 1 are not available, the required data can be obtained by driving the vehicle normally under actual traffic conditions. On a target test road segment, the vehicle is driven normally under actual traffic conditions, with the speed covering as much of the normal speed range as possible below the vehicle's speed limit. For example, if the maximum speed limit is 100 km / h, the vehicle can vary its speed in increments of no more than 20 km / h, adjusting the speed according to actual traffic conditions. Maintaining a stable driving state is not required, nor is increasing or decreasing speed mandatory. Driving at any speed is permissible as needed, but the speed variation should cover a range of 20–100 km / h. The vehicle can travel back and forth on the target road segment, avoiding sudden acceleration, deceleration, and large steering wheel adjustments as much as possible. After collecting sufficient speed coverage data, data collection can be stopped. Subsequent data collection will be used to determine the selection of actual calculation data and the chosen calculation formula. Vehicle data during sudden acceleration, deceleration, braking, gear shifting, and steering are removed. Data with speeds below 15 km / h and other obviously abnormal data are also removed. Actual operating data covering various speed points are extracted, and driving behavior of coasting in gear is determined by the accelerator pedal, gear position, and fuel injection signals.

[0059] Step 4: Data Acquisition. During vehicle operation, relevant data is collected at a frequency of at least 1Hz. Vehicle speed (V), engine speed (n), and engine torque (T) are collected via the CAN bus of the vehicle's OBD port. tq Engine friction torque (T) m Information such as throttle opening, gear position, and fuel injection signal is collected. Vehicle speed, acceleration (a), gradient (θ or i), and steering angle are acquired using GPS, gyroscopes, and accelerometers. If the vehicle has a built-in inertial navigation system, gradient, acceleration, and steering angle information can also be obtained from the vehicle's CAN bus. Acceleration (a) can be directly obtained from the accelerometer or calculated from the vehicle speed (V). The transmission system mechanical efficiency (η) can be provided by the vehicle manufacturer or a theoretically recommended value can be used. The vehicle mass (M) can be obtained by weighing or by calculating the load.

[0060] Step 5: Parameter Estimation. Based on the experimental data obtained in Step 4, the data is filtered, and data processing calculations are performed to obtain the estimated values ​​of the resistance curve coefficients of the vehicle on actual roads. If Method 1 is used, then according to Formula (1), the point-by-point quadratic function relationship between driving resistance and vehicle speed V at different speed stages is obtained. The values ​​of A, B, and C are obtained by analyzing the least squares regression method. If Method 2 is used, if the vehicle is in a coasting state, Formula (2) is selected; otherwise, Formula (1) is selected to obtain the point-by-point quadratic function relationship between driving resistance and different vehicle speeds V. The values ​​of A, B, and C are obtained by analyzing the least squares regression method.

[0061] Once the values ​​of A, B, and C are determined, if the vehicle has a built-in inertial navigation system, the slope information of the driving road can be obtained in real time during the actual control of the vehicle. Furthermore, road geographic information can also be obtained through the Internet of Vehicles. The vehicle can know the slope value of the route ahead in advance, and the actual road resistance can be estimated based on the resistance calculation formula, thereby predicting the power demand and providing a solution for predictive control of the vehicle.

[0062] The drag curve estimation algorithm is further illustrated below with a specific embodiment, taking the constant speed driving method as an example:

[0063] 1) The maximum speed of the test vehicle was limited to 100 km / h. Speeds of 20 km / h were selected as selection points: 20, 40, 60, 80, and 100 km / h. At each speed point, the vehicle was kept relatively stable for at least 60 seconds. Data was then filtered to remove data from acceleration, deceleration, braking, gear shifting, and steering maneuvers, as well as other obviously abnormal data. Only data from relatively stable operation at each speed point was collected. The final data points are shown below. Figure 4 As shown, each speed point data is approximately 400 seconds. In actual testing, the vehicle speed can be increased from low to high or decreased from high to low. If traffic conditions are limited, the test can be conducted in segments according to the actual situation, or the vehicle speed points can be randomly selected to complete the required data for each speed point.

[0064] 2) Because it is a basically straight road and the vehicle speed is basically stable, the slope resistance Fi and acceleration resistance F are... j The value is approximately 0 and can be ignored in the calculation. The mechanical efficiency η of the transmission system adopts the theoretically recommended value of 0.84. According to formula (1), the actual driving resistance F is finally calculated. t The second-by-second data corresponding to the vehicle speed V, such as Figure 5As shown in (a), the resistance is densely distributed across different vehicle speeds. Considering the fluctuations in both vehicle speed and resistance during actual driving, the average value of the data at each speed point can be taken. A quadratic fitting is then performed on the averaged curve, and the estimated values ​​of coefficients A, B, and C can be obtained using the least squares regression method. Figure 5 As shown in (b), in this specific embodiment, the least squares estimate of the actual road resistance curve coefficient is: A = 909.42, B = -4.7921, C = 0.179.

[0065] The method described in this invention can be used to estimate the coefficients of the actual road resistance curve of vehicles under various environmental and road conditions. Furthermore, due to advancements in sensor technology, some vehicles now possess built-in inertial navigation systems (including GPS, gyroscopes, accelerometers, etc.), enabling them to acquire relatively accurate information such as road slope angle, acceleration, and steering angle without relying on other instruments. The development of vehicle-to-everything (V2X) technology also makes it possible for vehicles to obtain real-time geographical information about the road ahead. Therefore, this invention can also be used for real-time prediction and estimation of actual road resistance. Specifically, based on the slope information, the slope resistance F is obtained. i By combining acceleration and deceleration requirements, vehicle speed status, and real-time estimated drag coefficients A, B, and C, the vehicle's traction requirements can be calculated and predicted in real time.

[0066] The above detailed description of a method for estimating the actual driving resistance of a vehicle, with reference to the embodiments, is illustrative rather than limiting. Several embodiments may be listed within the defined scope. Therefore, variations and modifications that do not depart from the overall concept of the present invention should be within the protection scope of the present invention.

Claims

1. A method for estimating the actual driving resistance of a vehicle, characterized by: The vehicle operates normally on actual roads. Through the vehicle bus, external instruments, or built-in sensors, it collects information on vehicle speed, engine speed, torque, friction torque, throttle opening, gear position, and fuel injection signals. Using GPS, gyroscopes, and accelerometers, or utilizing the vehicle's built-in inertial navigation system, it collects information on vehicle speed, acceleration, gradient, and steering angle. Based on this data, it estimates the actual road resistance curve coefficient. Combining this with gradient resistance and acceleration resistance calculations, it estimates the actual road resistance. The specific steps are as follows: Step 1: Determine traffic conditions, weather conditions, and road conditions to meet the vehicle operating environment requirements for data collection. Step 2: Determine the vehicle's preheating status, select a vehicle operating at medium to high speed to ensure the vehicle reaches the preheating requirements and the vehicle's coolant and engine oil temperatures reach a stable state. Step 3: Driving requirements. Select a relatively straight actual road and drive the vehicle with relatively stable driving behavior. Try to avoid sudden acceleration, deceleration and quick steering wheel adjustments. Record the required vehicle operation data in real time. Data on sudden acceleration, deceleration, braking, gear shifting and steering behaviors should be excluded from subsequent calculations. Step 4: Data Acquisition. During vehicle operation, relevant data is collected at a frequency of no less than 1Hz. This data is acquired via the CAN bus of the vehicle's OBD port, including vehicle speed V, engine speed n, and engine torque T. tq Engine friction torque T m The system collects information such as throttle opening, gear position, and fuel injection signal; it also uses GPS, gyroscope, and accelerometer to collect information such as vehicle speed, acceleration a, slope θ or i, and steering angle; and selects either the constant speed driving method or the actual driving speed segment extraction method to complete the data collection. Step 5: Parameter estimation. Based on the test data obtained in Step 4, the data is screened and processed to obtain the estimated value of the resistance curve coefficient of the vehicle on the actual road. If the constant speed driving method is adopted, the point-by-point quadratic function relationship between driving resistance and vehicle speed V is obtained according to formula (1). The values ​​of A, B, and C are obtained by analyzing the least squares regression method. （1） If the actual driving speed segment extraction method is used, if the vehicle is in a geared coasting state, then formula (2) is selected, otherwise formula (1) is selected, and the point-by-point quadratic function relationship between driving resistance and different vehicle speeds V is obtained. Based on the least squares regression method, the values ​​of A, B, and C are analyzed and obtained. （2） Where: η represents the mechanical efficiency of the transmission system, M is the vehicle mass, and m r For rotational mass.

2. The method for estimating the actual driving resistance of a vehicle according to claim 1, characterized in that: The determination of traffic conditions, weather conditions, and road conditions in step one is as follows: it shall be carried out under the conditions of no rain, snow, or fog, and is applicable to temperatures of -20 to 40°C, relative humidity of less than 95%, and altitudes below 5000m; road traffic index ≤ 2; wind speed ≤ level 2, average ground wind speed ≤ 3m / s, and gusts not greater than 5m / s.

3. The method for estimating the actual driving resistance of a vehicle according to claim 1, characterized in that: Step 4: Acquisition and calculation of actual vehicle operation data. Let F t T represents the driving force of a vehicle. tq Indicates engine torque, i g Let i0 represent the gear ratio of the transmission, i0 represent the gear ratio of the final drive, η represent the mechanical efficiency of the transmission system, and r be the wheel radius. Then the driving force F is... t for: If the vehicle is coasting in gear, the engine stops injecting fuel and is in a dragging state, the engine torque T tq If the value is negative, let it be T. m Then the driving force F t for: Among them, engine torque T tq and reverse torque T m The transmission ratio i is obtained and recorded in real time from the vehicle's CAN bus information. g The transmission ratio i0 of the main reducer is obtained through vehicle CAN bus information; the wheel radius r is selected as the static radius value of the wheel. The relationship between engine speed and vehicle speed is as follows: Where V is the vehicle's speed, obtained in real time from GPS or CAN bus information; n is the engine speed, obtained in real time from CAN bus information; and F is the vehicle's driving force. t The relationship between engine speed, torque, and vehicle speed is as follows: If the vehicle is in a coasting, reverse motion with gear engaged, the formula is: When a car travels at a constant speed on a level road, it needs to overcome rolling resistance from the ground and air resistance from the air; let the rolling resistance be F. f Air resistance is F w The slope resistance when a vehicle travels uphill is F. i When a vehicle accelerates, it also needs to overcome acceleration resistance F. j The driving force Ft of the vehicle is the sum of all resistance forces, that is: Among them, "F f +F w "A+B is a quadratic function of the vehicle's speed, which is also a quadratic function of the standard coasting method." V+C V 2 The resistance value determined by the values ​​A, B, and C in the figure; ramp resistance F i This is the component of a vehicle's weight along a slope when the vehicle is traveling on it. Under normal circumstances, the slope of most roads is relatively small. The road slope is expressed as the ratio of the slope height h to the base length s, that is: , Therefore, if the slope of the road is small, sinθ≈tanθ=i, then: Where M is the vehicle mass, g is the acceleration due to gravity, and θ is the longitudinal slope angle of the road; Acceleration resistance F j This is the inertial force that overcomes the acceleration of a vehicle's mass. A car's mass is divided into translational mass and rotational mass. When a car accelerates, the translational mass generates inertial force, while the rotational mass generates inertial torque. Where, m r Rotational mass refers to the equivalent effective mass of all rotating parts and wheels of a vehicle when it is traveling in neutral on a road, m. r It can be estimated based on 3% of the vehicle's baseline mass. Let 'a' be the vehicle's acceleration. From the above formula, we can derive: Combined with the above F t The calculation formula further yields: ， Right now: （1） Or, when coasting in gear: 。 （2） 4. The method for estimating the actual driving resistance of a vehicle according to claim 1, characterized in that: The constant speed driving method is a method for determining the vehicle drag coefficients A, B, and C under relatively straight road conditions and good traffic conditions. The highest test speed is selected based on the actual road speed limit and the vehicle's maximum speed limit. The vehicle speed is gradually changed from high speed to low speed or from low speed to high speed, with a change not exceeding 20 km / h, until the speed drops below 20 km / h. At each speed point, the speed is maintained for a period of time to ensure sufficient data acquisition. Data from a period where the speed is relatively stable and the driver has not engaged in sudden acceleration, deceleration, braking, gear shifting, or significant steering wheel adjustments is selected as the calculation data, and the formula is applied. (1) The data points corresponding to vehicle resistance and vehicle speed V at different speed stages are obtained second by second. Based on the least squares regression method, the values ​​of A, B and C are obtained.

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