Method and apparatus for measuring vehicle braking acceleration curve

Abstract

This application discloses a method and apparatus for measuring automotive braking acceleration curves, relating to the field of automotive technology. The method includes: acquiring spatial acceleration corresponding to the spatial tilt angle during vehicle movement; measuring the frictional acceleration experienced by the vehicle using a variable mass measurement method; measuring the wind resistance acceleration experienced by the vehicle using wind tunnel testing; and linearly superimposing the spatial acceleration, frictional acceleration, and wind resistance acceleration to obtain a calibrated engine braking acceleration curve. This application acquires spatial acceleration corresponding to the spatial tilt angle during vehicle movement using a portable acceleration curve acquisition device; linearly superimposing the spatial acceleration, frictional acceleration, and wind resistance acceleration eliminates the influence of factors such as wind resistance and ground friction on acceleration during driving; and after calibration, obtains the acceleration curve of a fuel-powered vehicle under engine braking alone, which can be used to optimize regenerative braking control strategies for electric vehicles.

Description

Technical Field

[0001] This application relates to the field of automotive technology, and in particular to a method and apparatus for measuring automotive braking acceleration curves. Background Technology

[0002] Vehicle acceleration G-force curve measurement refers to recording the changes in acceleration during vehicle acceleration and braking, and plotting the vehicle's G-force curve to evaluate its dynamic and handling performance. Furthermore, to improve vehicle handling, automakers are constantly exploring new technologies, including vehicle weight reduction, improvements to suspension and braking systems, and increased engine power; all of these require verification and evaluation based on vehicle G-force curve measurements. Currently, vehicle G-force curve measurement has become an indispensable technical means of evaluating vehicle performance.

[0003] However, measuring vehicle G-force curves often requires specialized equipment and procedures, and is highly integrated, lacking portable acquisition devices suitable for various vehicle models. There is also a lack of effective methods for describing acceleration G-force curves under engine braking alone. Summary of the Invention

[0004] The main purpose of this application is to provide a method and device for measuring the braking acceleration curve of an automobile, which aims to solve the technical problems that existing acceleration G-value curve measuring devices under engine braking alone are not portable enough and the G-value curves are not accurate enough.

[0005] To achieve the above objectives, this application proposes a method for measuring vehicle braking acceleration curves, the method comprising:

[0006] Collect spatial acceleration corresponding to the spatial tilt angle during vehicle movement;

[0007] The frictional acceleration generated by the frictional force acting on a vehicle is measured using the variable mass method.

[0008] The drag acceleration generated by wind resistance on a vehicle is measured through wind tunnel testing.

[0009] The spatial acceleration, frictional acceleration, and wind resistance acceleration are linearly superimposed to obtain the calibrated engine braking acceleration curve.

[0010] In one embodiment, the step of collecting the spatial acceleration corresponding to the spatial tilt angle during vehicle movement includes:

[0011] Acceleration, angle, and magnetic force information are collected using an IMU (Inertial Measurement Unit).

[0012] The acceleration information, angle information, and magnetic force value are fused using a nine-axis fusion algorithm to obtain the spatial tilt angle during vehicle movement.

[0013] The acceleration information is corrected based on the spatial tilt angle to obtain the spatial acceleration corresponding to the spatial tilt angle.

[0014] In one embodiment, the step of measuring the frictional acceleration generated by the frictional force acting on the vehicle using the variable mass measurement method includes:

[0015] The relationship between the total mass of the vehicle and the coefficient of kinetic friction in a predetermined number of experiments was determined by the variable mass measurement method.

[0016] Determine the total force relationship between the total mass of the vehicle, the acceleration measurement value in the preset number of experiments, wind resistance, the frictional force relationship, and the engine braking force;

[0017] The frictional acceleration is determined based on the frictional force relationship and the total force relationship.

[0018] In one embodiment, the step of linearly superimposing the spatial acceleration, frictional acceleration, and wind resistance acceleration to obtain the calibrated engine braking acceleration curve includes:

[0019] The acceleration relationship between the wind resistance acceleration and the engine braking acceleration is determined based on the friction acceleration and the total force relationship.

[0020] The engine braking acceleration is determined based on the acceleration relationship, and the calibrated engine braking acceleration curve is determined based on the engine braking acceleration.

[0021] In one embodiment, the step of determining the engine braking acceleration based on the acceleration relationship and determining the calibrated engine braking acceleration curve based on the engine braking acceleration includes:

[0022] The engine braking acceleration is determined based on the acceleration relationship, and the engine braking acceleration is corrected based on the spatial tilt angle to obtain the corrected engine braking acceleration.

[0023] The tuned engine braking acceleration curve is determined based on the actual coordinate system transformation matrix and the corrected engine braking acceleration.

[0024] In one embodiment, before the step of determining the calibrated engine braking acceleration curve based on the actual coordinate system transformation matrix and the corrected engine braking acceleration, the method further includes:

[0025] The rotation angles of the vehicle in the X, Y, and Z axes of the preset coordinate system are acquired by the IMU inertial unit, and a theoretical coordinate system transformation matrix is ​​established based on the rotation angles.

[0026] Acquire the acceleration values ​​of the vehicle in the X-axis, Y-axis and Z-axis directions in the preset coordinate system collected by the IMU inertial unit, and determine the angular relationship between the acceleration values ​​and the rotation angle;

[0027] The theoretical coordinate system transformation matrix is ​​transformed according to the angular relationship to obtain the actual coordinate system transformation matrix.

[0028] Furthermore, to achieve the above objectives, this application also proposes a vehicle braking acceleration curve measuring device, which includes:

[0029] The spatial acceleration acquisition module is used to acquire the spatial acceleration corresponding to the spatial tilt angle during vehicle movement;

[0030] The friction acceleration measurement module is used to measure the friction acceleration generated by the frictional force acting on a vehicle using the variable mass measurement method.

[0031] The drag acceleration measurement module is used to measure the drag acceleration generated by wind resistance on a vehicle through wind tunnel testing.

[0032] An acceleration tuning module is used to linearly superimpose the spatial acceleration, friction acceleration, and wind resistance acceleration to obtain a tuned engine braking acceleration curve.

[0033] In addition, to achieve the above objectives, this application also proposes a vehicle braking acceleration curve measurement device, the device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the vehicle braking acceleration curve measurement method as described above.

[0034] In addition, to achieve the above objectives, this application also proposes a storage medium, which is a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the steps of the vehicle braking acceleration curve measurement method described above.

[0035] In addition, to achieve the above objectives, this application also provides a computer program product, which includes a computer program that, when executed by a processor, implements the steps of the vehicle braking acceleration curve measurement method described above.

[0036] This application provides a method for measuring automotive braking acceleration curves. The method involves collecting spatial acceleration corresponding to the spatial tilt angle during vehicle movement; measuring frictional acceleration generated by frictional forces acting on the vehicle using a variable mass measurement method; and measuring wind resistance acceleration generated by wind resistance acting on the vehicle using wind tunnel testing. The spatial acceleration, frictional acceleration, and wind resistance acceleration are then linearly superimposed to obtain a calibrated engine braking acceleration curve. This application uses a portable acceleration curve acquisition device to collect spatial acceleration corresponding to the spatial tilt angle during vehicle movement. The linear superposition of spatial acceleration, frictional acceleration, and wind resistance acceleration eliminates the influence of wind resistance, ground friction, and other factors on the acceleration measurement results during driving. After calibration, the acceleration curve of a fuel-powered vehicle under engine braking alone is obtained, which can then be used to optimize regenerative braking control strategies for electric vehicles. Attached Figure Description

[0037] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0038] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a flowchart illustrating an embodiment of the vehicle braking acceleration curve measurement method of this application.

[0040] Figure 2 This is an overall flowchart of the vehicle braking acceleration curve measurement method of this application;

[0041] Figure 3 This is a hardware design block diagram of the acceleration acquisition device of this application;

[0042] Figure 4 This is a schematic diagram of the throttle (electric switch) release detection mechanism of this application;

[0043] Figure 5 This is a schematic diagram illustrating the data display of the mobile app in this application;

[0044] Figure 6 A schematic diagram illustrating the processing flow of the JY901 sensor dataset in this application;

[0045] Figure 7 This is a flowchart illustrating Embodiment 2 of the vehicle braking acceleration curve measurement method of this application;

[0046] Figure 8This is a schematic diagram of the forces acting on a vehicle during braking in this application;

[0047] Figure 9 This is a flowchart illustrating Embodiment 3 of the method for measuring vehicle braking acceleration curves in this application.

[0048] Figure 10 This is a schematic diagram illustrating the effect of vehicle body tilt angle on acceleration in this application;

[0049] Figure 11 This is a force analysis diagram of the vehicle in this application when it encounters an uneven road surface on the test road;

[0050] Figure 12 This is a schematic diagram of the module structure of the vehicle braking acceleration curve measuring device according to an embodiment of this application;

[0051] Figure 13 This is a schematic diagram of the equipment structure of the hardware operating environment involved in the vehicle braking acceleration curve measurement method in the embodiments of this application.

[0052] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0053] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0054] To better understand the technical solution of this application, a detailed description will be provided below in conjunction with the accompanying drawings and specific implementation methods.

[0055] The main solution of this application embodiment is: to collect the spatial acceleration corresponding to the spatial tilt angle during vehicle driving; to measure the friction acceleration generated by the friction force on the vehicle through the variable mass measurement method; to measure the wind resistance acceleration generated by the wind resistance on the vehicle through wind tunnel testing; and to linearly superimpose the spatial acceleration, friction acceleration and wind resistance acceleration to obtain the tuned engine braking acceleration curve.

[0056] Vehicle G-force measurement involves recording changes in acceleration during acceleration and braking to create a G-force curve, which is used to evaluate a vehicle's dynamic and handling performance. Furthermore, to improve handling, automakers continuously explore new technologies, including vehicle weight reduction, improvements to suspension and braking systems, and increased engine power, all of which require verification and evaluation based on G-force measurement. Currently, vehicle G-force measurement has become an indispensable technique for evaluating vehicle performance. However, G-force measurement often requires specialized equipment and procedures, is highly integrated, and lacks portable acquisition devices suitable for various vehicle models. There is also a lack of effective methods for describing the acceleration G-force curve under engine braking alone.

[0057] This application provides a solution that collects spatial acceleration corresponding to the spatial tilt angle during vehicle movement; measures frictional acceleration generated by frictional force acting on the vehicle using a variable mass measurement method; and measures wind resistance acceleration generated by wind resistance acting on the vehicle using wind tunnel testing. The spatial acceleration, frictional acceleration, and wind resistance acceleration are then linearly superimposed to obtain a calibrated engine braking acceleration curve. This application uses a portable acceleration curve acquisition device to collect spatial acceleration corresponding to the spatial tilt angle during vehicle movement; the spatial acceleration, frictional acceleration, and wind resistance acceleration are linearly superimposed to eliminate the influence of wind resistance, ground friction, and other factors on the acceleration measurement results during driving. After calibration, the acceleration curve of a fuel-powered vehicle under engine braking alone is obtained, which can then be used to optimize the regenerative braking control strategy of electric vehicles.

[0058] It should be noted that the executing entity of the method in this embodiment can be a portable acceleration curve acquisition device with functions of vehicle braking acceleration curve measurement, network communication, and program execution; it can also be a vehicle braking acceleration curve measurement device with the same or similar functions; or it can be a vehicle equipped with the aforementioned vehicle braking acceleration curve measurement device. This embodiment and the following embodiments will be described using a vehicle braking acceleration curve measurement device as an example.

[0059] Based on this, embodiments of this application provide a method for measuring vehicle braking acceleration curves, referring to... Figure 1 , Figure 1 This is a flowchart illustrating the first embodiment of the vehicle braking acceleration curve measurement method of this application.

[0060] In this embodiment, the method for measuring the vehicle braking acceleration curve includes steps S10 to S40:

[0061] Step S10: Collect the spatial acceleration corresponding to the spatial tilt angle during vehicle movement.

[0062] It is understood that this embodiment uses a portable data acquisition device suitable for various vehicle models to obtain the vehicle's acceleration curve after the accelerator pedal is released. The acceleration data acquired by the sensors is processed, and after calibration, the acceleration curve of a gasoline-powered vehicle under engine braking alone is obtained. The flow of the measurement method is explained with reference to the figures. Figure 2 This is a flowchart illustrating the overall process of the vehicle braking acceleration curve measurement method described in this application. In the development of the data acquisition device, a throttle (electric switch) release detection mechanism is designed, using the release signal as the trigger signal for the angle sensor and acceleration sensor. The spatial tilt angle and corresponding spatial acceleration during vehicle movement are collected, with the acceleration sensor's fixed position and initial fixed angle taking full account of their effects. After saving the collected data, the acceleration values ​​are calibrated. The acceleration caused by ground friction is obtained using a variable mass measurement method, and the drag coefficient is obtained through wind tunnel testing, thus yielding the acceleration caused by wind resistance. Combining these factors, and based on the principle of linear superposition, the calibrated engine braking acceleration curve is finally obtained for use in optimizing the regenerative braking control strategy for electric vehicles.

[0063] It should be noted that this embodiment provides a portable data acquisition device suitable for various vehicle models. Choosing a suitable sensor mounting position and angle is crucial. Since vibration and vehicle noise are significant during speed measurement, potentially affecting the actual data, it is recommended to place the sensor in the center of the passenger compartment. This facilitates device calibration and testing, reduces the impact of the external environment on the speed measurement device, and ensures more accurate sensor data acquisition, minimizing inaccuracies caused by angular deviations. Furthermore, the components of gravitational acceleration in various directions should be measured when the device is stationary to calculate the pitch and roll angles of the current inertial measurement unit relative to the road surface. A user-friendly sensor triggering strategy should be designed to reduce human intervention during the measurement process, thereby minimizing errors caused by human factors and making the measurements more accurate.

[0064] In specific implementation, you can refer to Figure 3 The hardware design block diagram of the acceleration acquisition device illustrates the device. The microcontroller is responsible for data forwarding and preprocessing, communicating with the throttle sensor via Bluetooth to accurately obtain the current throttle release time. It also communicates with the IMU (Inertial Measurement Unit) via Bluetooth to acquire real-time acceleration and angle information after throttle release. After acquiring the data, the actual acceleration components are calculated in real time, and the raw and fitted data are recorded. The fitted data is made more accurate by changing the vehicle's load. Simultaneously, the data is displayed on the observer's mobile phone via WiFi in web page format, showing the measurement results in real time.

[0065] Understandably, the throttle sensor can use an infrared distance module. By setting a threshold, it can start recording acceleration data and transmitting it back to the microcontroller via Bluetooth once the distance exceeds that threshold. The throttle (electric switch) release detection mechanism can be referenced. Figure 4 .

[0066] Additionally, the mobile device can connect to the WiFi signal emitted by the local microcontroller to access the corresponding webpage to view real-time data, or open a dedicated app to view downloaded data. A diagram illustrating the mobile app's data display can be found here. Figure 5 .

[0067] In one feasible implementation, step S10 may include steps S101 to S103:

[0068] Step S101: Acceleration information, angle information and magnetic force value are collected through the IMU inertial unit.

[0069] Step S102: The acceleration information, the angle information, and the magnetic force value are fused using a nine-axis fusion algorithm to obtain the spatial tilt angle during vehicle movement.

[0070] Step S103: Correct the acceleration information according to the spatial tilt angle to obtain the spatial acceleration corresponding to the spatial tilt angle.

[0071] It should be understood that the IMU (Inertial Measurement Unit) can use the JY901 sensor, a nine-axis sensor that integrates a three-axis velocity sensor, a three-axis accelerometer, and a three-axis magnetometer. It can use a nine-axis fusion algorithm to obtain accurate angle data, which can be used to correct acceleration measurement errors caused by installation errors and vehicle tilting during movement. Specific data for this module are shown in Table 1 below. The JY901 sensor dataset processing flow can be found in [reference needed]. Figure 6 .

[0072] Table 1 JY901 Accelerometer Parameters

[0073]

[0074]

[0075] In this embodiment, acceleration information, angle information, and magnetic force values ​​are collected by an IMU inertial unit, and a nine-axis fusion algorithm is used to obtain accurate angle data. The accurate angle data can correct the acceleration measurement error caused by installation error and vehicle tilt during movement.

[0076] Step S20: Measure the frictional acceleration generated by the frictional force acting on the vehicle using the variable mass measurement method.

[0077] Step S30: Measure the drag acceleration caused by wind resistance on the vehicle through wind tunnel testing.

[0078] Step S40: The spatial acceleration, friction acceleration and wind resistance acceleration are linearly superimposed to obtain the calibrated engine braking acceleration curve.

[0079] Understandably, the collected data can be saved and the acceleration values ​​can be tuned. The acceleration of the vehicle due to ground friction can be obtained using the variable mass measurement method. The drag coefficient can be obtained through wind tunnel testing, and then the acceleration of the vehicle due to drag can be obtained. Combining the above, the tuned engine braking acceleration curve can be finally obtained according to the principle of linear superposition, so as to be used for the optimization of electric vehicle regenerative braking control strategy in the future.

[0080] This embodiment provides a method for measuring vehicle braking acceleration curves. It collects the spatial acceleration corresponding to the spatial tilt angle during vehicle movement; measures the frictional acceleration generated by the frictional force acting on the vehicle using a variable mass measurement method; and measures the wind resistance acceleration generated by the wind resistance acting on the vehicle using wind tunnel testing. The spatial acceleration, frictional acceleration, and wind resistance acceleration are linearly superimposed to obtain a calibrated engine braking acceleration curve. This embodiment uses a portable acceleration curve acquisition device to collect the spatial acceleration corresponding to the spatial tilt angle during vehicle movement. The linear superposition of spatial acceleration, frictional acceleration, and wind resistance acceleration eliminates the influence of wind resistance, ground friction, and other factors on the acceleration measurement results during driving. After calibration, the acceleration curve of a fuel-powered vehicle under engine braking alone is obtained, which can then be used to optimize regenerative braking control strategies for electric vehicles.

[0081] Based on the first embodiment of this application, in the second embodiment of this application, the content that is the same as or similar to that in Embodiment 1 above can be referred to the above description, and will not be repeated hereafter. Based on this, please refer to... Figure 7 Step S20, the method for measuring the vehicle braking acceleration curve further includes steps S201 to S203:

[0082] Step S201: Determine the relationship between the total mass of the vehicle and the frictional force corresponding to the coefficient of kinetic friction in a preset number of experiments using the variable mass measurement method.

[0083] Understandably, this embodiment can process the acceleration data collected by the sensor, eliminating the influence of factors such as wind resistance and road friction on the acceleration measurement results during driving, and obtaining the acceleration curve of the fuel vehicle under engine braking alone after calibration. Factors such as wind resistance and road friction can cause the measured acceleration to be not completely parallel to the road surface, leading to inaccurate measurement data. They can also cause the measured acceleration to include not only engine braking acceleration but also acceleration from other resistance forces. Using inaccurate data in electric vehicles can result in an excessively large acceleration G-value during deceleration. Therefore, methods such as changing the vehicle's mass and performing multiple measurements are used to eliminate the influence of friction and wind resistance, obtaining a more accurate engine braking acceleration G-value.

[0084] It should be understood that engine braking acceleration can be indirectly measured using the variable mass measurement method. The force F generated by engine braking when the vehicle is loaded is... RB Wind resistance F w Frictional resistance F f like Figure 8 As shown. When the vehicle load is changed, F f The resistance will also change accordingly, while the wind resistance will not change for the same vehicle. Rolling friction is related to tire material, contact surface conditions, etc., and is not related to the load. Therefore, the drag component in the measured acceleration can be eliminated.

[0085] In the specific implementation, two experiments are used as an example for illustration. Let m1 and m2 be the total mass in the two experiments, μ be the coefficient of kinetic friction, and g be the acceleration due to gravity. According to Newton's second law, the relationship of friction is as shown in formula (1):

[0086]

[0087] Step S202: Determine the total mass of the vehicle, the acceleration measurement value in the preset number of experiments, the wind resistance, the frictional force relationship, and the total force relationship between the engine braking force.

[0088] It should be noted that if the acceleration measurements in the two experiments are a1 and a2 respectively, F w F is the wind resistance experienced by the vehicle. RB Assuming the braking force of the vehicle's engine is given, the overall force relationship can be obtained as shown in formula (2) below:

[0089]

[0090] Step S203: Determine the friction acceleration based on the frictional force relationship and the total force relationship.

[0091] It should be understood that simplifying the above formulas (1) and (2) yields the friction acceleration as shown in formula (3):

[0092]

[0093] In one feasible implementation, step S40 may include steps S401 to S402:

[0094] Step S401: Determine the acceleration relationship between the wind resistance acceleration and the engine braking acceleration based on the friction acceleration and the total force relationship.

[0095] It is understandable that, based on the friction acceleration shown in formula (3) and the total force relationship shown in formula (2), the acceleration relationship between wind resistance acceleration and engine braking acceleration can be derived as shown in formula (4):

[0096]

[0097] Among them, a w a is the acceleration caused by wind resistance acting on the vehicle body. RB This refers to engine braking acceleration.

[0098] Step S402: Determine the engine braking acceleration based on the acceleration relationship, and determine the calibrated engine braking acceleration curve based on the engine braking acceleration.

[0099] It should be understood that wind resistance does not change for the same vehicle, while rolling friction is related to tire material, contact surface conditions, etc., and is independent of load. Therefore, the drag component in the measured acceleration can be eliminated. Thus, wind resistance acceleration can be expressed as shown in formula (5):

[0100]

[0101] Among them, a w C represents the acceleration of the vehicle body under the influence of wind resistance. w ρ represents the drag coefficient, S represents the air density, v represents the projected area of ​​the front of the vehicle, m represents the vehicle speed, and m represents the vehicle mass.

[0102] Based on formulas (5) and (4), the engine braking acceleration a can be obtained. RB As shown in formula (6):

[0103]

[0104] The engine braking acceleration is determined based on the acceleration relationship, and then the tuned engine braking acceleration curve is determined based on the obtained engine braking acceleration.

[0105] In this embodiment, the relationship between wind resistance acceleration and engine braking acceleration can be obtained by transforming the friction acceleration and the total force relationship, thus eliminating the influence of factors such as wind resistance and ground friction on the acceleration measurement results during driving, thereby obtaining a more accurate engine braking acceleration.

[0106] In this embodiment, since the frictional force changes when the vehicle load is changed, the frictional acceleration can be calculated by changing the mass of the vehicle using the variable mass measurement method, combining the total mass of the vehicle and the acceleration measurement value with Newton's second law.

[0107] Based on the first embodiment of this application, in the third embodiment of this application, the content that is the same as or similar to that in the first embodiment described above can be referred to the above description, and will not be repeated hereafter. Based on this, please refer to... Figure 9 In step S40, the method for measuring the vehicle braking acceleration curve further includes steps S403 to S404:

[0108] Step S403: Determine the engine braking acceleration based on the acceleration relationship, and correct the engine braking acceleration based on the spatial tilt angle to obtain the corrected engine braking acceleration.

[0109] Step S404: Determine the tuned engine braking acceleration curve based on the actual coordinate system transformation matrix and the corrected engine braking acceleration.

[0110] It's understandable that when the vehicle brakes using engine braking, the vehicle will tilt forward due to rearward resistance. The effect of vehicle tilt angle on acceleration can be found by referring to... Figure 10 , Figure 10 This diagram illustrates the effect of vehicle tilt angle on acceleration in this application. In the diagram, g represents the downward vertical acceleration experienced by the vehicle when stationary, g' is the gravitational acceleration measured when the vehicle tilts forward, a represents the acceleration during engine braking, and a' represents the acceleration after the vehicle tilts during engine braking. The acceleration value a' measured by the nine-axis sensor will have an error due to the presence of θ. The nine-axis sensor can measure this tiny pitch angle θ, and thus, a can be corrected using known data.

[0111] a=a′cosθ (7)

[0112] To obtain accurate vehicle acceleration, it is generally necessary to ensure that the test surface remains level throughout, without any slight inclines or declines, to avoid the influence of gravity on vehicle acceleration. The effect of gravity on acceleration can be found in [reference needed]. Figure 11 , Figure 11 This is a schematic diagram illustrating the effect of gravity on acceleration in this application. However, this approach is costly and has many inconveniences. When the vehicle is traveling uphill or downhill, the nine-axis sensor can measure the vehicle's pitch angle during this process. Then, by correcting with known data and eliminating the influence of gravity on acceleration, an accurate acceleration value is obtained. When the nine-axis sensor collects data on the vehicle going uphill, the corresponding pitch angle is positive, and when going downhill, it is negative, which facilitates program processing.

[0113]

[0114] Based on the processed and analyzed deceleration data, a deceleration model is developed to simulate the deceleration curve of a vehicle. Using physical simulation or mathematical modeling methods, a deceleration model is established according to the characteristics and patterns of the deceleration data, and the model is then validated and optimized. Finally, the calibrated engine braking acceleration curve is determined based on the actual coordinate system transformation matrix and the corrected engine braking acceleration.

[0115] In one feasible implementation, steps A10 to A30 may be included before step S404:

[0116] Step A10: Obtain the rotation angles of the vehicle in the X, Y, and Z axes of the preset coordinate system collected by the IMU inertial unit, and establish a theoretical coordinate system transformation matrix based on the rotation angles.

[0117] It should be noted that the data acquired by the IMU inertial unit, read by the JY901 sensor, represents the angular velocities of rotation in three directions. Let α be the angle between the X-axis and the vehicle's forward direction or a direction perpendicular to the forward direction; let β be the angle between the Y-axis and the vehicle's forward direction or a direction perpendicular to the forward direction; and let γ be the angle between the Z-axis and the vehicle's forward direction or a direction perpendicular to the forward direction; where γ = 0. Then, the theoretical coordinate system transformation matrix is:

[0118]

[0119] Step A20: Obtain the acceleration values ​​of the vehicle in the X-axis, Y-axis and Z-axis directions in the preset coordinate system collected by the IMU inertial unit, and determine the angular relationship between the acceleration values ​​and the rotation angle.

[0120] It is understood that when the accelerometer is in a stable state, the acceleration values ​​detected by the accelerometer on the X-axis, Y-axis, and Z-axis are respectively components of the gravitational acceleration g, g' ... x g y and g z Then we have:

[0121]

[0122] Step A30: Transform the theoretical coordinate system transformation matrix according to the angular relationship to obtain the actual coordinate system transformation matrix.

[0123] It is understandable that, based on the angular relationship in formula (10) and the theoretical coordinate system transformation matrix in formula (9), the actual coordinate system transformation matrix can be obtained as follows:

[0124]

[0125] In this embodiment, when the vehicle body brakes, the vehicle body will tilt forward due to the rearward resistance. The engine braking acceleration is corrected based on the spatial tilt angle caused by the forward tilt of the vehicle body, and then the tuned engine braking acceleration curve can be obtained by combining it with the actual coordinate system transformation matrix.

[0126] It should be noted that the above examples are only for understanding this application and do not constitute a limitation on the vehicle braking acceleration curve measurement method of this application. Any simple modifications based on this technical concept are within the protection scope of this application.

[0127] This application also provides a device for measuring the braking acceleration curve of an automobile; please refer to [reference needed]. Figure 12 The vehicle braking acceleration curve measuring device includes:

[0128] The spatial acceleration acquisition module 10 is used to acquire the spatial acceleration corresponding to the spatial tilt angle during vehicle movement.

[0129] Friction acceleration measurement module 20 is used to measure the friction acceleration generated by the frictional force acting on the vehicle by a variable mass measurement method;

[0130] The drag acceleration measurement module 30 is used to measure the drag acceleration generated by the wind resistance experienced by the vehicle through wind tunnel testing.

[0131] The acceleration tuning module 40 is used to linearly superimpose the spatial acceleration, friction acceleration and wind resistance acceleration to obtain the tuned engine braking acceleration curve.

[0132] The vehicle braking acceleration curve measuring device provided in this application, employing the vehicle braking acceleration curve measuring method in the above embodiments, can solve the technical problem. Compared with the prior art, the beneficial effects of the vehicle braking acceleration curve measuring device provided in this application are the same as those of the vehicle braking acceleration curve measuring method provided in the above embodiments, and other technical features in the vehicle braking acceleration curve measuring device are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0133] This application provides a vehicle braking acceleration curve measurement device, which includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the vehicle braking acceleration curve measurement method in the above embodiment 1.

[0134] The following is for reference. Figure 13 This document illustrates a structural schematic diagram of an automotive braking acceleration curve measuring device suitable for implementing embodiments of this application. The automotive braking acceleration curve measuring device in this application may include, but is not limited to, mobile terminals such as mobile phones, laptops, digital radio receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Description), PMPs (Portable Media Players), and in-vehicle terminals (e.g., in-vehicle navigation terminals), as well as fixed terminals such as digital TVs and desktop computers. Figure 13 The illustrated vehicle braking acceleration curve measuring device is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0135] like Figure 13As shown, the vehicle braking acceleration curve measurement device may include a processing unit 1001 (e.g., a central processing unit, a graphics processing unit, etc.), which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 1002 or a program loaded from a storage device 1003 into a random access memory (RAM) 1004. The RAM 1004 also stores various programs and data required for the operation of the vehicle braking acceleration curve measurement device. The processing unit 1001, ROM 1002, and RAM 1004 are interconnected via a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Typically, the following systems can be connected to I / O interface 1006: input devices 1007 including, for example, touchscreens, touchpads, keyboards, mice, image sensors, microphones, accelerometers, gyroscopes, etc.; output devices 1008 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; storage devices 1003 including, for example, magnetic tapes, hard disks, etc.; and communication devices 1009. Communication device 1009 allows the vehicle braking acceleration curve measuring device to communicate wirelessly or wiredly with other devices to exchange data. Although a vehicle braking acceleration curve measuring device with various systems is shown in the figure, it should be understood that it is not required to implement or possess all the systems shown. More or fewer systems may be implemented alternatively.

[0136] Specifically, according to the embodiments disclosed in this application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments disclosed in this application include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device, or installed from storage device 1003, or installed from ROM 1002. When the computer program is executed by processing device 1001, it performs the functions defined in the methods of the embodiments disclosed in this application.

[0137] The vehicle braking acceleration curve measuring device provided in this application, employing the vehicle braking acceleration curve measuring method in the above embodiments, can solve the technical problem of vehicle braking acceleration curve measurement. Compared with the prior art, the beneficial effects of the vehicle braking acceleration curve measuring device provided in this application are the same as those of the vehicle braking acceleration curve measuring method provided in the above embodiments, and other technical features of this vehicle braking acceleration curve measuring device are the same as those disclosed in the previous embodiment method, and will not be repeated here.

[0138] It should be understood that the various parts disclosed in this application can be implemented using hardware, software, firmware, or a combination thereof. In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0139] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0140] This application provides a computer-readable storage medium having computer-readable program instructions (i.e., a computer program) stored thereon, the computer-readable program instructions being used to execute the vehicle braking acceleration curve measurement method in the above embodiments.

[0141] The computer-readable storage medium provided in this application may be, for example, a USB flash drive, but is not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, system, or device. The program code contained on the computer-readable storage medium may be transmitted using any suitable medium, including but not limited to: wires, optical cables, RF (Radio Frequency), etc., or any suitable combination thereof.

[0142] The aforementioned computer-readable storage medium may be included in the vehicle braking acceleration curve measuring device; or it may exist independently and not assembled into the vehicle braking acceleration curve measuring device.

[0143] The aforementioned computer-readable storage medium carries one or more programs. When the aforementioned one or more programs are executed by the vehicle braking acceleration curve measuring device, the vehicle braking acceleration curve measuring device: collects the spatial acceleration corresponding to the spatial tilt angle during vehicle movement; measures the friction acceleration generated by the friction force acting on the vehicle through a variable mass measurement method; measures the wind resistance acceleration generated by the wind resistance acting on the vehicle through wind tunnel testing; and linearly superimposes the spatial acceleration, friction acceleration, and wind resistance acceleration to obtain the calibrated engine braking acceleration curve.

[0144] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a Local Area Network (LAN) or a Wide Area Network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0145] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0146] The modules described in the embodiments of this application can be implemented in software or hardware. The names of the modules do not necessarily limit the functionality of the unit itself.

[0147] The readable storage medium provided in this application is a computer-readable storage medium that stores computer-readable program instructions (i.e., a computer program) for executing the above-described vehicle braking acceleration curve measurement method, thereby solving the technical problem. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in this application are the same as those of the vehicle braking acceleration curve measurement method provided in the above embodiments, and will not be repeated here.

[0148] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the steps of the vehicle braking acceleration curve measurement method described above.

[0149] The computer program product provided in this application can solve the technical problem. Compared with the prior art, the beneficial effects of the computer program product provided in this application are the same as those of the automobile braking acceleration curve measurement method provided in the above embodiments, and will not be repeated here.

[0150] The above description is only a part of the embodiments of this application and does not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included in the patent protection scope of this application.

Claims

1. A method for measuring the braking acceleration curve of a vehicle, characterized in that, The method includes: Collect spatial acceleration corresponding to the spatial tilt angle during vehicle movement; The frictional acceleration generated by the frictional force acting on a vehicle is measured using the variable mass method. The drag acceleration generated by wind resistance on a vehicle is measured through wind tunnel testing. The spatial acceleration, frictional acceleration, and wind resistance acceleration are linearly superimposed to obtain the tuned engine braking acceleration curve. The step of collecting the spatial acceleration corresponding to the spatial tilt angle during vehicle movement includes: Acceleration, angle, and magnetic force information are collected using an IMU (Inertial Measurement Unit). The acceleration information, angle information, and magnetic force value are fused using a nine-axis fusion algorithm to obtain the spatial tilt angle during vehicle movement. The acceleration information is corrected based on the spatial tilt angle to obtain the spatial acceleration corresponding to the spatial tilt angle.

2. The method as described in claim 1, characterized in that, The step of measuring the frictional acceleration generated by the frictional force acting on the vehicle using the variable mass measurement method includes: The relationship between the total mass of the vehicle and the coefficient of kinetic friction in a predetermined number of experiments was determined by the variable mass measurement method. Determine the total force relationship between the total mass of the vehicle, the acceleration measurement value in the preset number of experiments, wind resistance, the frictional force relationship, and the engine braking force; The frictional acceleration is determined based on the frictional force relationship and the total force relationship.

3. The method as described in claim 2, characterized in that, The step of linearly superimposing the spatial acceleration, frictional acceleration, and wind resistance acceleration to obtain the calibrated engine braking acceleration curve includes: The acceleration relationship between the wind resistance acceleration and the engine braking acceleration is determined based on the friction acceleration and the total force relationship. The engine braking acceleration is determined based on the acceleration relationship, and the calibrated engine braking acceleration curve is determined based on the engine braking acceleration.

4. The method as described in claim 3, characterized in that, The steps of determining the engine braking acceleration based on the acceleration relationship and determining the calibrated engine braking acceleration curve based on the engine braking acceleration include: The engine braking acceleration is determined based on the acceleration relationship, and the engine braking acceleration is corrected based on the spatial tilt angle to obtain the corrected engine braking acceleration. The tuned engine braking acceleration curve is determined based on the actual coordinate system transformation matrix and the corrected engine braking acceleration.

5. The method as described in claim 4, characterized in that, Before the step of determining the calibrated engine braking acceleration curve based on the actual coordinate system transformation matrix and the corrected engine braking acceleration, the method further includes: The rotation angles of the vehicle in the X, Y, and Z axes of the preset coordinate system are acquired by the IMU inertial unit, and a theoretical coordinate system transformation matrix is ​​established based on the rotation angles. Acquire the acceleration values ​​of the vehicle in the X-axis, Y-axis and Z-axis directions in the preset coordinate system collected by the IMU inertial unit, and determine the angular relationship between the acceleration values ​​and the rotation angle; The theoretical coordinate system transformation matrix is ​​transformed according to the angular relationship to obtain the actual coordinate system transformation matrix.

6. A device for measuring automobile braking acceleration curves, characterized in that, The vehicle braking acceleration curve measuring device includes: The spatial acceleration acquisition module is used to acquire the spatial acceleration corresponding to the spatial tilt angle during vehicle movement; The friction acceleration measurement module is used to measure the friction acceleration generated by the frictional force acting on a vehicle using the variable mass measurement method. The drag acceleration measurement module is used to measure the drag acceleration generated by wind resistance on a vehicle through wind tunnel testing. An acceleration tuning module is used to linearly superimpose the spatial acceleration, friction acceleration and wind resistance acceleration to obtain a tuned engine braking acceleration curve. The step of collecting the spatial acceleration corresponding to the spatial tilt angle during vehicle movement includes: Acceleration, angle, and magnetic force information are collected using an IMU (Inertial Measurement Unit). The acceleration information, angle information, and magnetic force value are fused using a nine-axis fusion algorithm to obtain the spatial tilt angle during vehicle movement. The acceleration information is corrected based on the spatial tilt angle to obtain the spatial acceleration corresponding to the spatial tilt angle.

7. A device for measuring automobile braking acceleration curves, characterized in that, The device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, the computer program being configured to implement the steps of the vehicle braking acceleration curve measurement method as described in any one of claims 1 to 5.

8. A storage medium, characterized in that, The storage medium is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by a processor, it implements the steps of the vehicle braking acceleration curve measurement method as described in any one of claims 1 to 5.

9. A computer program product, characterized in that, The computer program product includes a computer program that, when executed by a processor, implements the steps of the vehicle braking acceleration curve measurement method as described in any one of claims 1 to 5.

Images