Method and system for measuring vehicle center of gravity height

Abstract

The present invention discloses a method and system for measuring the center of gravity height of a vehicle. The method obtains the static radius of the tire, the load-deformation characteristics of the tire, the suspension stiffness characteristics, the axle load, and the wheelbase of the two axles. When the vehicle is located on a horizontal surface and undergoes an emergency braking test, the braking deceleration of the vehicle and the suspension characteristic pressure height data before and during braking are obtained. The axle load change during the emergency braking test is calculated based on the suspension stiffness characteristics and the suspension characteristic pressure height data. The center of gravity height and the center of gravity height change during braking are calculated based on the axle load, the axle load change, the wheelbase of the two axles, the braking deceleration, the static radius of the tire, the load-deformation characteristics of the tire, the axle load, and the suspension characteristic pressure height data. The center of gravity height of the entire vehicle is calculated based on the center of gravity height and the center of gravity height change during braking. The method is applicable to two-axle vehicles and vehicles that can be simplified as two-axle vehicles. The method calculates the axle load transfer of the vehicle during a stable longitudinal tilt process and accurately measures the center of gravity height of the entire vehicle.

Description

Technical Field

[0001] The present invention relates to the field of vehicle technology, and in particular to a method and system for measuring the height of the center of gravity of a vehicle Background Art

[0002] As one of the important basic parameters of a vehicle, the vehicle's center of gravity height has a significant impact on the vehicle's dynamic performance, which is mainly reflected in power, braking, handling stability and ride smoothness. For example, the body posture, suspension status and steering characteristics during acceleration, braking and steering will be affected by the vehicle's center of gravity height. Therefore, accurately obtaining the vehicle's center of gravity height is an important task for vehicle manufacturers and repair shops.

[0003] Currently, the most basic vehicle type is the two-axle vehicle. When obtaining the center of gravity height of such vehicles, the valuation method is generally used based on experience. This requires the main manufacturer to have certain test conditions to conduct tests. Due to the influence of the test conditions, the deviation from the actual situation is large, resulting in inaccurate valuation methods. There is also a method of raising a certain axle, which is more suitable for passenger cars, which have a small mass and are easy to lift the axle, but is not very suitable for commercial vehicles. In addition, the process of raising the vehicle often involves some processing methods such as suspension locking, which makes the measured center of gravity height deviate from the actual one. When the roll method is applied to air suspension, it is more difficult to determine the roll center. Summary of the Invention

[0004] The present invention provides a method and system for measuring the center of gravity height of a vehicle, which is applicable to two-axle vehicles and vehicles that can be simplified as two-axle vehicles. The method calculates the axle load transfer of the vehicle during a stable longitudinal tilt process and accurately measures the center of gravity height of the entire vehicle.

[0005] In order to solve the above technical problems, an embodiment of the present invention provides a method for measuring the center of gravity height of a vehicle, comprising:

[0006] Obtain the static radius of the vehicle's tires, the load-deformation characteristics of the tires, the suspension stiffness characteristics, the axle load, and the wheelbase of the two axles;

[0007] When the vehicle is on a horizontal surface for an emergency brake test, obtain the vehicle's braking deceleration, and suspension characteristic pressure height data before and during braking;

[0008] Calculate the axle load change in the emergency brake test based on the suspension stiffness characteristics and suspension characteristic pressure height data;

[0009] Calculate the center of gravity height and center of gravity height change during braking based on axle load, axle load change, wheelbase of both axles, braking deceleration, tire static radius, tire load deformation characteristics, axle load and suspension characteristic pressure height data;

[0010] The center of gravity height of the entire vehicle is calculated based on the center of gravity height and the change in center of gravity height during braking.

[0011] In implementing the embodiments of the present invention, an emergency braking test is conducted on a vehicle located on a horizontal surface to cause the vehicle to pitch. The center of gravity height during braking is calculated using data such as the axle load change and braking deceleration. The center of gravity height change during emergency braking is calculated using data such as the axle load, suspension characteristic pressure height data, and tire load deformation characteristics. The center of gravity height during braking is corrected using the center of gravity height change, and the center of gravity height of the entire vehicle at static state can be accurately calculated. This method is applicable to two-axle vehicles and vehicles that can be simplified to be considered two-axle. It calculates the axle load transfer of the vehicle during a stable pitch and accurately obtains the center of gravity height of the entire vehicle. It is also applicable to any vehicle load condition, and the center of gravity height of the entire vehicle can be calculated regardless of whether it is empty or fully loaded.

[0012] As a preferred solution, the static radius of the tire, the load deformation characteristics of the tire, the suspension stiffness characteristics, the axle load and the wheelbase of the two axles of the vehicle are obtained, wherein the suspension stiffness characteristics are obtained, specifically:

[0013] When the front suspension of the vehicle is a leaf spring suspension, obtaining the leaf spring stiffness of the suspension;

[0014] When the front suspension of the vehicle is an air suspension, the relationship between the height and load of the air spring is obtained.

[0015] When implementing the embodiment of the present invention, when the front suspension of the vehicle is different, the main influencing factors of the axle load change in the emergency braking test are different. The corresponding suspension stiffness characteristics are obtained in different situations, which facilitates the calculation of the axle load change in the emergency braking test in different ways.

[0016] As a preferred solution, when the vehicle is on a horizontal surface for an emergency braking test, the vehicle's braking deceleration, and suspension characteristic pressure height data before and during braking are obtained, specifically:

[0017] When the front suspension of the vehicle is a leaf spring suspension, obtaining the braking deceleration of the vehicle and the suspension height before and during braking;

[0018] When the front suspension of the vehicle is an air suspension, the braking deceleration of the vehicle, the suspension height before and during braking, and the air spring pressure values ​​before and during braking are obtained.

[0019] By implementing the embodiments of the present invention, vehicle-related data is obtained when the vehicle is placed on a horizontal surface and an emergency braking test is performed. No special test equipment, measurement equipment, or test items are required, and data measurement can be completed using conventional emergency braking tests and conventional test equipment in the vehicle development process.

[0020] As a preferred solution, the axle load change in the emergency braking test is calculated based on the suspension stiffness characteristics and the suspension characteristic pressure height data, specifically:

[0021] When the vehicle's front suspension is a leaf spring suspension, the axle load change during the emergency brake test is calculated based on the leaf spring stiffness and the suspension height before and during braking. The formula is as follows:

[0022] △M=(h f1 -h f2 )*K lf / g;

[0023] Among them, △M is the change of axle load, h f1 is the front suspension height before braking, h f2 is the front suspension height during braking, g is the acceleration due to gravity, K lf is the leaf spring stiffness of the front suspension;

[0024] Alternatively, the axle load change during the emergency brake test can be calculated using the following formula:

[0025] △M=(h r2 -h r1 )*K lr / g;

[0026] Among them, h r2 is the rear suspension height when braking, h r1 is the rear suspension height before braking, K lr is the leaf spring stiffness of the rear suspension;

[0027] When the vehicle's front suspension is an air suspension, the axle load change during the emergency braking test is calculated based on the relationship between the air spring height and load, the suspension height before and during braking, and the air spring pressure before and during braking. Specifically, the loads of the air spring before and during braking are obtained based on the suspension height before and during braking, the air spring pressure before and during braking, and the relationship between the air spring height and load. Then, the axle load change during the emergency braking test is calculated based on the loads of the air spring before and during braking. The formula is as follows:

[0028] △M=(F f2 -F f1 ) / g;

[0029] Among them, F f2 is the load of the front suspension air spring during braking, F f1 It is the load of the front suspension air spring before braking;

[0030] Alternatively, the axle load change during the emergency brake test can be calculated using the following formula:

[0031] △M=(F r1 -F r2 ) / g;

[0032] Among them, F r1 is the load of the rear suspension air spring before braking, F r2 It is the load of the rear suspension air spring during braking.

[0033] In implementing an embodiment of the present invention, when the vehicle's front suspension is a leaf spring suspension, the axle load change is calculated based on the leaf spring stiffness and the change in suspension height before and after braking. If the decrease in rear axle load is equal to the increase in front axle load, the axle load change for either axle can be calculated, simplifying the calculation process. When the vehicle's front suspension is an air suspension, the air spring load can be determined based on the air spring's load-deformation characteristics. The air spring load before and after the height change during an emergency braking test is obtained. This simple method allows the calculated air spring load change to be the axle load change.

[0034] As a preferred solution, the center of gravity height and the center of gravity height change during braking are calculated based on the axle load, axle load change, the wheelbase of the two axles, the braking deceleration, the static radius of the tire, the load deformation characteristics of the tire, the axle load and the suspension characteristic pressure height data, specifically:

[0035] Calculate the center of gravity height during braking based on the axle load, axle load change, wheelbase of the two axles, and braking deceleration;

[0036] The change in center of gravity height is calculated based on the static radius of the tire, the load-deformation characteristics of the tire, the wheelbase of the two axles, the axle load and the suspension characteristic pressure height data.

[0037] As a preferred solution, the center of gravity height during braking is calculated based on the axle load, axle load change, the wheelbase of the two axles, and the braking deceleration. Specifically, it is:

[0038] According to the wheelbase and axle load of the two axles, calculate the distance from the center of gravity of the vehicle to the front axle. The formula is as follows:

[0039] L f =M r *L / M f ;

[0040] Among them, L f is the distance from the center of gravity of the vehicle to the front axle, L is the wheelbase of the two axles, M f is the front axle load, M r is the rear axle load;

[0041] The center of gravity height during braking is calculated based on the axle load, the distance from the vehicle's center of gravity to the front axle, the change in axle load, the wheelbase of the two axles, and the braking deceleration. The formula is as follows:

[0042] h=[(M f +Mr )*g*L f -(M r -△M)*g*L] / [(M f +M r )*a];

[0043] Where h is the height of the center of gravity during braking, a is the braking deceleration, △M is the change in axle load, and g is the acceleration due to gravity.

[0044] As a preferred solution, the center of gravity height change is calculated based on the static radius of the tire, the load deformation characteristics of the tire, the wheelbase of the two axles, the axle load and the suspension characteristic pressure height data, specifically:

[0045] The deformation of the tire radius is obtained based on the axle load, the static radius of the tire, and the load deformation characteristics of the tire. The height change of the tire and suspension is then calculated based on the deformation of the tire radius before and during braking and the suspension height before and during braking.

[0046] Calculate the height change of the tire and suspension of the front axle using the following formula;

[0047] △h f =(△r tf2 -△r tf1 )+(h f1 -h f2 );

[0048] Among them, △h f is the height change of the tire and suspension of the front axle, △r tf2 is the deformation of the front suspension tire radius during braking, △r tf1 is the deformation of the front suspension tire radius before braking, h f1 is the front suspension height before braking, h f2 is the front suspension height when braking;

[0049] Calculate the height change of the tire and suspension of the rear axle using the following formula:

[0050] △h r =(△r tr2 -△r tr1 )+(h r2 -h r1 );

[0051] Among them, △h r is the height change of the tire and suspension of the rear axle, △r tr2 is the deformation of the rear suspension tire radius during braking, △r tr1 is the deformation of the rear suspension tire radius before braking, h r2 is the rear suspension height when braking, h r1is the rear suspension height before braking;

[0052] According to the distance from the center of gravity of the vehicle to the front axle and the wheelbase of the two axles, calculate the distance from the center of gravity of the vehicle to the rear axle. The formula is as follows:

[0053] L r =LL f ;

[0054] Among them, L r is the distance from the center of gravity of the vehicle to the rear axle, L is the wheelbase of the two axles, L f is the distance from the vehicle's center of gravity to the front axle;

[0055] The height change of the center of gravity is calculated based on the height change of the tire and suspension of the front axle, the height change of the tire and suspension of the rear axle, and the distance from the center of gravity of the vehicle to the rear axle. The formula is as follows:

[0056] △h=L r *(△h f +△h r ) / L-△h r ;

[0057] Where △h is the change in the center of gravity height.

[0058] By implementing the embodiments of the present invention, the deformation of the front and rear suspensions before and after braking can be easily checked based on the load-deformation characteristics of the tires, thereby respectively calculating the height increase of the axle tires and suspensions of the front and rear axles in the emergency braking test. Based on the triangular relationship, the height change of the center of gravity of the entire vehicle during emergency braking can be accurately calculated.

[0059] As a preferred solution, in order to solve the same technical problem, an embodiment of the present invention further provides a vehicle center of gravity height measurement system, comprising: a static data acquisition module, a braking test data acquisition module, a braking test data calculation module and a vehicle center of gravity height calculation module;

[0060] The static data acquisition module is used to obtain the static radius of the vehicle's tires, the load deformation characteristics of the tires, the suspension stiffness characteristics, the axle load and the wheelbase of the two axles;

[0061] The braking test data acquisition module is used to obtain the vehicle's braking deceleration, suspension characteristic pressure height data before and during braking when the vehicle is on a horizontal surface for an emergency braking test;

[0062] The braking test data calculation module is used to calculate the axle load change in the emergency braking test based on the suspension stiffness characteristics and the suspension characteristic pressure height data. It is also used to calculate the center of gravity height and the center of gravity height change during braking based on the axle load, axle load change, the wheelbase of the two axles, the braking deceleration, the static radius of the tire, the load deformation characteristics of the tire, the axle load and the suspension characteristic pressure height data.

[0063] The vehicle center of gravity height calculation module is used to calculate the center of gravity height of the vehicle according to the center of gravity height and the change in center of gravity height during braking.

[0064] As a preferred solution, the static data acquisition module includes a leaf spring suspension static data acquisition unit and an air suspension static data acquisition unit, wherein the leaf spring suspension static data acquisition unit is used to obtain the static radius of the tire, the load-deformation characteristics of the tire, the axle load, the wheelbase of the two axles, and the leaf spring stiffness of the suspension; the air suspension static data acquisition unit is used to obtain the static radius of the tire, the load-deformation characteristics of the tire, the axle load, the wheelbase of the two axles, and the relationship between the height and load of the air spring;

[0065] The braking test data acquisition module includes a leaf spring suspension braking data acquisition unit and an air suspension braking data acquisition unit. The leaf spring suspension braking data acquisition unit is used to acquire the vehicle's braking deceleration, suspension height before and during braking, and the air suspension braking data acquisition unit is used to acquire the vehicle's braking deceleration, suspension height before and during braking, and air spring pressure value before and during braking.

[0066] As a preferred solution, the braking test data calculation module includes an axle load change calculation unit, a center of gravity height calculation unit during braking, and a center of gravity height change calculation unit;

[0067] The axle load variation calculation unit is used to calculate the axle load variation during the emergency braking test based on the suspension stiffness characteristics and the suspension characteristic pressure height data. Specifically, when the vehicle's front suspension is a leaf spring suspension, the axle load variation during the emergency braking test is calculated based on the leaf spring stiffness of the suspension and the suspension height before and during braking. The formula is as follows:

[0068] △M=(h f1 -h f2 )*K lf / g;

[0069] Among them, △M is the change of axle load, h f1 is the front suspension height before braking, h f2 is the front suspension height during braking, g is the acceleration due to gravity, K lf is the leaf spring stiffness of the front suspension;

[0070] Alternatively, the axle load change during the emergency brake test can be calculated using the following formula:

[0071] △M=(h r2 -h r1 )*K lr / g;

[0072] Among them, h r2 is the rear suspension height when braking, h r1is the rear suspension height before braking, K lr is the leaf spring stiffness of the rear suspension;

[0073] When the vehicle's front suspension is an air suspension, the axle load change during the emergency braking test is calculated based on the relationship between the air spring height and load, the suspension height before and during braking, and the air spring pressure before and during braking. Specifically, the loads of the air spring before and during braking are obtained based on the suspension height before and during braking, the air spring pressure before and during braking, and the relationship between the air spring height and load. Then, the axle load change during the emergency braking test is calculated based on the loads of the air spring before and during braking. The formula is as follows:

[0074] △M=(F f2 -F f1 ) / g;

[0075] Among them, F f2 is the load of the front suspension air spring during braking, F f1 It is the load of the front suspension air spring before braking;

[0076] Alternatively, the axle load change during the emergency brake test can be calculated using the following formula:

[0077] △M=(F r1 -F r2 ) / g;

[0078] Among them, F r1 is the load of the rear suspension air spring before braking, F r2 It is the load of the rear suspension air spring during braking;

[0079] The center of gravity height calculation unit during braking is used to calculate the center of gravity height during braking based on the axle load, axle load change, the wheelbase of the two axles and the braking deceleration. Specifically:

[0080] According to the wheelbase and axle load of the two axles, calculate the distance from the center of gravity of the vehicle to the front axle. The formula is as follows:

[0081] L f =M r *L / M f ;

[0082] Among them, L f is the distance from the center of gravity of the vehicle to the front axle, L is the wheelbase of the two axles, M f is the front axle load, M r is the rear axle load;

[0083] The center of gravity height during braking is calculated based on the axle load, the distance from the vehicle's center of gravity to the front axle, the change in axle load, the wheelbase of the two axles, and the braking deceleration. The formula is as follows:

[0084] h=[(M f +M r )*g*L f -(M r -△M)*g*L] / [(M f +M r )*a];

[0085] Where h is the height of the center of gravity during braking, a is the braking deceleration, △M is the change in axle load, and g is the acceleration due to gravity;

[0086] The center of gravity height change calculation unit is used to calculate the center of gravity height change based on the static radius of the tire, the load deformation characteristics of the tire, the wheelbase of the two axles, the axle load and the suspension characteristic pressure height data, specifically:

[0087] The deformation of the tire radius is obtained based on the axle load, the static radius of the tire, and the load deformation characteristics of the tire. The height change of the tire and suspension is then calculated based on the deformation of the tire radius before and during braking and the suspension height before and during braking.

[0088] Calculate the height change of the tire and suspension of the front axle using the following formula;

[0089] △h f =(△r tf2 -△r tf1 )+(h f1 -h f2 );

[0090] Among them, △h f is the height change of the tire and suspension of the front axle, △r tf2 is the deformation of the front suspension tire radius during braking, △r tf1 is the deformation of the front suspension tire radius before braking, h f1 is the front suspension height before braking, h f2 is the front suspension height when braking;

[0091] Calculate the height change of the tire and suspension of the rear axle using the following formula:

[0092] △h r =(△r tr2 -△r tr1 )+(h r2 -h r1 );

[0093] Among them, △h r is the height change of the tire and suspension of the rear axle, △r tr2 is the deformation of the rear suspension tire radius during braking, △r tr1 is the deformation of the rear suspension tire radius before braking, hr2 is the rear suspension height when braking, h r1 is the rear suspension height before braking;

[0094] According to the distance from the center of gravity of the vehicle to the front axle and the wheelbase of the two axles, calculate the distance from the center of gravity of the vehicle to the rear axle. The formula is as follows:

[0095] L r =LL f ;

[0096] Among them, L r is the distance from the center of gravity of the vehicle to the rear axle, L is the wheelbase of the two axles, L f is the distance from the vehicle's center of gravity to the front axle;

[0097] The height change of the center of gravity is calculated based on the height change of the tire and suspension of the front axle, the height change of the tire and suspension of the rear axle, and the distance from the center of gravity of the vehicle to the rear axle. The formula is as follows:

[0098] △h=L r *(△h f +△h r ) / L-△h r ;

[0099] Where △h is the change in the center of gravity height. BRIEF DESCRIPTION OF THE DRAWINGS

[0100] Figure 1 : A schematic flow chart of an embodiment of a method for measuring the height of the center of gravity of a vehicle provided by the present invention;

[0101] Figure 2 : A characteristic diagram showing the relationship between tire load and deformation according to an embodiment of the method for measuring the vehicle center of gravity height provided by the present invention;

[0102] Figure 3 : A characteristic diagram showing the relationship between the height and load of an air spring according to an embodiment of the method for measuring the height of the center of gravity of a vehicle provided by the present invention;

[0103] Figure 4 : A load relationship diagram of an air spring according to an embodiment of the method for measuring the height of the center of gravity of a vehicle provided by the present invention;

[0104] Figure 5 : A relationship diagram of the deformation amount of the tire radius according to an embodiment of the method for measuring the vehicle center of gravity height provided by the present invention;

[0105] Figure 6 : A triangular relationship diagram of the change in the height of the vehicle's center of gravity before and after braking according to an embodiment of the method for measuring the height of the vehicle's center of gravity provided by the present invention;

[0106] Figure 7: A structural schematic diagram of another embodiment of the method for measuring the vehicle center of gravity height provided by the present invention. DETAILED DESCRIPTION

[0107] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0108] Example 1

[0109] Please refer to Figure 1 , which is a flow chart of a method for measuring the center of gravity height of a vehicle provided by an embodiment of the present invention. This method for measuring the center of gravity height of a vehicle is applicable to two-axle vehicles and vehicles that can be simplified as two-axle vehicles. This embodiment accurately measures the center of gravity height of the vehicle by performing an emergency braking test on a horizontal surface and calculating the axle load transfer during a stable pitching process. The measurement method includes steps 101 to 105, each of which is specifically as follows:

[0110] Step 101: Obtain the static radius of the tire, the load-deformation characteristics of the tire, the suspension stiffness characteristics, the axle load, and the wheelbase of the two axles of the vehicle.

[0111] In this embodiment, obtaining the static radius of the vehicle tire refers to obtaining the tire size radius r t The static radius of the tire can be obtained by, but is not limited to, checking the national standard and the supplier's model spectrum; the load deformation characteristics of the tire (F t -△r t ) is the relationship between the load and deformation of the tire, such as Figure 2 As shown, it can be found through but not limited to the supplier's experimental results data; the suspension stiffness characteristics include the relationship between the leaf spring stiffness of the suspension, the height of the air spring and the load, which can be found through but not limited to the supplier's experimental results data; the axle load includes the front axle load M f and rear axle load M r , which can be obtained by, but is not limited to, weighing with an axle load meter; when the vehicle is a two-axle vehicle, the wheelbase L of the two axles is the distance between the front axle and the rear axle; when the vehicle is simplified as a two-axle vehicle, the wheelbase L of the two axles is the simplified distance between one axle and the other axle.

[0112] Optionally, the static radius of the vehicle's tires, the load-deformation characteristics of the tires, the suspension stiffness characteristics, the axle load, and the wheelbase of the two axles are obtained, wherein the suspension stiffness characteristics are obtained, specifically:

[0113] When the front suspension of the vehicle is a leaf spring suspension, obtaining the leaf spring stiffness of the suspension;

[0114] When the front suspension of the vehicle is an air suspension, the relationship between the height and load of the air spring is obtained.

[0115] In this embodiment, different suspension stiffness characteristics are obtained according to different types of vehicle front suspensions. When the vehicle front suspension is a leaf spring suspension, the leaf spring stiffness of the suspension is obtained, including the leaf spring stiffness K of the front suspension. lf and the leaf spring stiffness K of the rear suspension lr ,When the front suspension of the vehicle is air suspension, obtain the relationship characteristics of the air spring height and load, such as Figure 3 As shown, the relationship characteristic includes the relationship characteristic h between the height and load of the front air spring. af —F af , and the relationship between the height and load of the rear air spring h ar —F ar .

[0116] When the front suspension of the vehicle is different, the main influencing factors of the axle load change in the emergency braking test are different. The corresponding suspension stiffness characteristics are obtained in different situations to facilitate the calculation of the axle load change in the emergency braking test in different ways.

[0117] Step 102: When the vehicle is located on a horizontal surface and undergoes an emergency braking test, the braking deceleration of the vehicle and the suspension characteristic pressure height data before and during braking are obtained.

[0118] In this embodiment, the following equipment is installed on the vehicle: an acceleration sensor and a displacement sensor. The acceleration sensor is installed at the middle crossbeam of the frame, and the displacement sensor is installed between the axle and the frame of the front and rear axles. When the front suspension is an air suspension, an air pressure sensor is installed at the air spring interface. After the equipment is installed, the vehicle is subjected to an emergency braking test on a horizontal plane to obtain the following parameters during the emergency braking test: the vehicle braking deceleration a (inertia force acceleration), the suspension characteristic pressure height data before braking, and the suspension characteristic pressure height data during braking. The suspension characteristic pressure height data includes the suspension height and the air spring pressure value.

[0119] Acquiring vehicle-related data during an emergency brake test with the vehicle positioned on a horizontal surface eliminates the need for specialized test equipment, measurement devices, and test items. Data measurement can be accomplished using routine emergency brake tests and conventional test equipment used during vehicle development.

[0120] Optionally, when the front suspension of the vehicle is a leaf spring suspension, obtaining the braking deceleration of the vehicle and the suspension height before and during braking;

[0121] When the front suspension of the vehicle is an air suspension, the braking deceleration of the vehicle, the suspension height before and during braking, and the air spring pressure values ​​before and during braking are obtained.

[0122] In this embodiment, when the front suspension of the vehicle is a leaf spring suspension, the suspension characteristic pressure height data is the suspension height, including the front suspension height h before braking. f1 , front suspension height during braking h f2 , Rear suspension height before braking h r1 and rear suspension height h during braking r2 When the vehicle's front suspension is air suspension, the suspension characteristic pressure data is the suspension height and air spring pressure value, including the front suspension height h before braking. f1 , front suspension height during braking h f2 , Rear suspension height before braking h r1 , rear suspension height during braking h r2 , front air spring pressure value P before braking f1 , front air spring pressure value P during braking f2 , Rear air spring pressure value P before braking r1 and the rear air spring pressure value P before braking r2 .

[0123] Step 103: Calculate the axle load change in the emergency braking test based on the suspension stiffness characteristics and the suspension characteristic pressure height data.

[0124] In this embodiment, when the front suspension of the vehicle is a leaf spring suspension, the suspension stiffness characteristic is the leaf spring stiffness of the suspension, and the suspension characteristic pressure height data is the suspension height before and during braking. When the front suspension of the vehicle is an air suspension, the suspension stiffness characteristic is the relationship characteristic between the height and load of the air spring, and the suspension characteristic pressure height data is the suspension height before and during braking and the air spring pressure value before and during braking.

[0125] Optionally, when the front suspension of the vehicle is a leaf spring suspension, the axle load change in the emergency brake test is calculated based on the leaf spring stiffness of the suspension and the suspension height before and during braking. The formula is as follows:

[0126] △M=(h f1 -h f2 )*K lf / g;

[0127] Among them, △M is the change of axle load, h f1 is the front suspension height before braking, h f2 is the front suspension height during braking, g is the acceleration due to gravity, K lf is the leaf spring stiffness of the front suspension;

[0128] Alternatively, the axle load change during the emergency brake test can be calculated using the following formula:

[0129] △M=(hr2 -h r1 )*K lr / g;

[0130] Among them, h r2 is the rear suspension height when braking, h r1 is the rear suspension height before braking, K lr is the leaf spring stiffness of the rear suspension;

[0131] When the vehicle's front suspension is an air suspension, the axle load change during the emergency braking test is calculated based on the relationship between the air spring height and load, the suspension height before and during braking, and the air spring pressure before and during braking. Specifically, the loads of the air spring before and during braking are obtained based on the suspension height before and during braking, the air spring pressure before and during braking, and the relationship between the air spring height and load. Then, the axle load change during the emergency braking test is calculated based on the loads of the air spring before and during braking. The formula is as follows:

[0132] △M=(F f2 -F f1 ) / g;

[0133] Among them, F f2 is the load of the front suspension air spring during braking, F f1 It is the load of the front suspension air spring before braking.

[0134] Alternatively, the axle load change during the emergency brake test can be calculated using the following formula:

[0135] △M=(F r1 -F r2 ) / g;

[0136] Among them, F r1 is the load of the rear suspension air spring before braking, F r2 It is the load of the rear suspension air spring during braking.

[0137] In this embodiment, the axle load change during the vehicle emergency braking test refers to the axle load transfer. The reduction in the rear axle load is equal to the increase in the front axle load. Therefore, the axle load transfer of any axle can be calculated. When the front suspension of the vehicle is a leaf spring suspension, the stiffness K of the front suspension leaf spring is known. lf , front suspension height h before braking in emergency braking test f1 and front suspension height h during braking f2 , the axle load change (increase in front axle load) can be calculated as: △M=(h f1 -h f2 )*K lf / g, similarly, given the stiffness K of the rear suspension leaf spring lr, front suspension height h before braking in emergency braking test f1 and front suspension height h during braking f2 , the axle load change (reduction in rear axle load) can be calculated as △M=(h r2 -h r1 )*K lr / g. When the front suspension of the vehicle is an air suspension, the height of the front suspension air spring (i.e., front air suspension) before braking during the emergency braking test is h f1 and air pressure P f1 The load F of the front suspension air spring before braking can be checked based on the load deformation characteristics of the air spring. f1 ,like Figure 4 As shown, the height h of the front suspension air spring during the emergency braking test is also known. f2 The load F of the front suspension air spring after the height change can be obtained according to the load deformation characteristics of the air spring. f2 The difference between the front and rear loads of the front suspension air spring is the axle load variation △M=(F f2 -F f1 ) / g, similarly, the load deformation characteristics of the air spring are checked to see the load F of the rear suspension air spring before braking. r1 , and the height h of the rear suspension air spring during the emergency braking test is known r2 The load F of the rear suspension air spring after the height change can be obtained according to the load deformation characteristics of the air spring. r2 The difference between the loads before and after the rear suspension air spring brake is the axle load change △M=(F r1 -F r2 ) / g.

[0138] When the vehicle's front suspension is a leaf spring, the axle load change is calculated based on the leaf spring stiffness and the change in suspension height before and after braking. Since the decrease in rear axle load equals the increase in front axle load, the axle load change for either axle can be calculated, simplifying the calculation process. When the vehicle's front suspension is an air suspension, the air spring load can be determined based on its load-deformation characteristics. This method is simple, and the calculated air spring load change is the axle load change.

[0139] Step 104: Calculate the center of gravity height and the center of gravity height change during braking based on the axle load, axle load change, the wheelbase of the two axles, the braking deceleration, the static radius of the tire, the load deformation characteristics of the tire, the axle load and the suspension characteristic pressure height data.

[0140] Optionally, the center of gravity height during braking is calculated based on the axle load, axle load change, the wheelbase of the two axles, and the braking deceleration;

[0141] The change in center of gravity height is calculated based on the static radius of the tire, the load-deformation characteristics of the tire, the wheelbase of the two axles, the axle load and the suspension characteristic pressure height data.

[0142] Optionally, the center of gravity height during braking is calculated based on the axle load, axle load change, the wheelbase of the two axles, and the braking deceleration, specifically:

[0143] According to the wheelbase and axle load of the two axles, calculate the distance from the center of gravity of the vehicle to the front axle. The formula is as follows:

[0144] L f =M r *L / M f ;

[0145] Among them, L f is the distance from the center of gravity of the vehicle to the front axle, L is the wheelbase of the two axles, M f is the front axle load, M r is the rear axle load;

[0146] The center of gravity height during braking is calculated based on the axle load, the distance from the vehicle's center of gravity to the front axle, the change in axle load, the wheelbase of the two axles, and the braking deceleration. The formula is as follows:

[0147] h=[(M f +M r )*g*L f -(M r -△M)*g*L] / [(M f +M r )*a];

[0148] Where h is the height of the center of gravity during braking, a is the braking deceleration, △M is the change in axle load, and g is the acceleration due to gravity.

[0149] In this embodiment, when the front axle load M is known f , rear axle load M r , the wheelbase L of the two axles can be used to calculate the distance L from the center of gravity of the vehicle to the front axle f =M r *L / M f , and then according to the distance L from the center of gravity of the vehicle to the front axle f , axle load change △M, wheelbase L of the two axles and braking deceleration a, vehicle center of gravity height h, the axle load equation before and after braking in the emergency braking test can be obtained, (M f +M r )*g*L f =(M f +M r )*a*h+(M r -△M)*g*L, the equation can be transformed to calculate the center of gravity height during braking h=[(M f+M r )*g*L f -(M r -△M)*g*L] / [(M f +M r )*a].

[0150] Optionally, the center of gravity height change is calculated based on the static radius of the tire, the load deformation characteristics of the tire, the wheelbase of the two axles, the axle load and the suspension characteristic pressure height data. The center of gravity height change is calculated as follows:

[0151] The deformation of the tire radius is obtained based on the axle load, the static radius of the tire, and the load deformation characteristics of the tire. The height change of the tire and suspension is then calculated based on the deformation of the tire radius before and during braking and the suspension height before and during braking.

[0152] Calculate the height change of the tire and suspension of the front axle using the following formula;

[0153] △h f =(△r tf2 -△r tf1 )+(h f1 -h f2 );

[0154] Among them, △h f is the height change of the tire and suspension of the front axle, △r tf2 is the deformation of the front suspension tire radius during braking, △r tf1 is the deformation of the front suspension tire radius before braking, h f1 is the front suspension height before braking, h f2 is the front suspension height when braking;

[0155] Calculate the height change of the tire and suspension of the rear axle using the following formula:

[0156] △h r =(△r tr2 -△r tr1 )+(h r2 -h r1 );

[0157] Among them, △h r is the height change of the tire and suspension of the rear axle, △r tr2 is the deformation of the rear suspension tire radius during braking, △r tr1 is the deformation of the rear suspension tire radius before braking, h r2 is the rear suspension height when braking, h r1 is the rear suspension height before braking;

[0158] According to the distance from the center of gravity of the vehicle to the front axle and the wheelbase of the two axles, calculate the distance from the center of gravity of the vehicle to the rear axle. The formula is as follows:

[0159] L r =LL f ;

[0160] Among them, L r is the distance from the center of gravity of the vehicle to the rear axle, L is the wheelbase of the two axles, L f is the distance from the vehicle's center of gravity to the front axle;

[0161] The height change of the center of gravity is calculated based on the height change of the tire and suspension of the front axle, the height change of the tire and suspension of the rear axle, and the distance from the center of gravity of the vehicle to the rear axle. The formula is as follows:

[0162] △h=L r *(△h f +△h r ) / L-△h r ;

[0163] Where △h is the change in the center of gravity height.

[0164] In this embodiment, the static radius of the tire (tire specifications) and the axle load values ​​before and during braking are known during the emergency braking test. Based on the load-deformation characteristics of the tire, the deformation of the front suspension tire radius before braking, Δr, can be obtained. tf1 ,like Figure 5 As shown, the deformation of the front suspension tire radius during braking is △r tf2 , the deformation of the rear suspension tire radius before braking △r tr1 and the deformation of the rear suspension tire radius during braking △r tr2 , thus the tire radius before and during braking can be obtained, the front axle tire radius r before braking tf1 =r t -△r tf1 , front wheel tire radius r during braking tf2 =r t -△r tf2 , Rear axle tire radius r before braking tr1 =r t -△r tr1 , Rear wheel tire radius r during braking tf2 =r t -△r tr2 Then, according to the front suspension height h before braking obtained during the emergency braking test, f1 , front suspension height during braking h f2 , Rear suspension height before braking h r1 , rear suspension height h during braking r2When the emergency braking test process is completed, the height change of the front axle tire and suspension (the height increase of the front axle tire and suspension) △h can be calculated. f =(△r tf2 -△r tf1 )+(h f1 -h f2 ); height change of the rear axle tire and suspension (height reduction of the rear axle tire and suspension) △h r =(△r tr2 -△r tr1 )+(h r2 -h r1 ), the triangular relationship of the change in center of gravity height before and after braking, such as Figure 6 As shown in the figure, the equation for the change in the vehicle's center of gravity height during emergency braking can be obtained: (△h+△h r ) / (△h r +△h f )=L r / L, transforming the above formula, we can calculate the change in center of gravity height △h=L r *(△h f +△h r ) / L-△h r .

[0165] Based on the load-deformation characteristics of the tires, the deformation of the front and rear suspensions before and after braking can be easily checked, thereby calculating the height increase of the axle tires and suspensions of the front and rear axles in the emergency braking test respectively. Based on the triangular relationship, the height change of the center of gravity of the entire vehicle during emergency braking can be accurately calculated.

[0166] Step 105: Calculate the vehicle's center of gravity height based on the center of gravity height and the center of gravity height change during braking.

[0167] In this embodiment, the height of both the front and rear suspensions changes during the emergency braking test. Therefore, the braking center of gravity height calculated above needs to be corrected to obtain the static vehicle center of gravity height. The braking center of gravity height and the change in center of gravity height are numerically calculated to calculate the vehicle center of gravity height. As an example of this embodiment, the braking center of gravity height h and the change in center of gravity height are summed to calculate the vehicle center of gravity height H = h + Δh.

[0168] This embodiment utilizes an emergency braking test with the vehicle positioned on a horizontal surface to induce pitch. The center of gravity height during braking is calculated using data such as axle load change and braking deceleration. The center of gravity height change during emergency braking is calculated using data such as axle load, suspension characteristic pressure height, and tire load-deformation characteristics. The center of gravity height during braking is corrected using this change in center of gravity height, allowing for accurate calculation of the vehicle's static center of gravity height. This method is applicable to two-axle vehicles, as well as vehicles that can be simplified to be considered two-axle vehicles. It calculates axle load transfer during a stable pitch, accurately obtaining the vehicle's center of gravity height. It is also applicable to any vehicle load condition, whether empty or fully loaded, and can calculate the vehicle's center of gravity height.

[0169] Example 2

[0170] Accordingly, see Figure 7 , Figure 7 FIG. 1 is a schematic diagram of the structure of the second embodiment of the vehicle center of gravity height measurement system provided by the present invention. Figure 7 As shown, the vehicle center of gravity height measurement system includes a static data acquisition module 701, a brake test data acquisition module 702, a brake test data calculation module 703, and a vehicle center of gravity height calculation module 704; wherein, the static data acquisition module 701 is used to obtain the static radius of the vehicle tire, the load deformation characteristics of the tire, the suspension stiffness characteristics, the axle load, and the wheelbase of the two axles;

[0171] The static data acquisition module 701 is used to obtain the static radius of the vehicle's tires, the load-deformation characteristics of the tires, the suspension stiffness characteristics, the axle load, and the wheelbase of the two axles;

[0172] Optionally, the static data acquisition module 701 includes a leaf spring suspension static data acquisition unit 7011 and an air suspension static data acquisition unit 7012, wherein the leaf spring suspension static data acquisition unit 7011 is used to acquire the static radius of the tire, the load-deformation characteristics of the tire, the axle load, the wheelbase of the two axles, and the leaf spring stiffness of the suspension; the air suspension static data acquisition unit 7012 is used to acquire the static radius of the tire, the load-deformation characteristics of the tire, the axle load, the wheelbase of the two axles, and the relationship between the height and load of the air spring;

[0173] The braking test data acquisition module 702 is used to acquire the vehicle's braking deceleration, and suspension characteristic pressure height data before and during braking when the vehicle is on a horizontal surface and undergoing an emergency braking test;

[0174] Optionally, the braking test data acquisition module 702 includes a leaf spring suspension braking data acquisition unit 7021 and an air suspension braking data acquisition unit 7022, wherein the leaf spring suspension braking data acquisition unit 7021 is used to acquire the vehicle's braking deceleration, suspension height before and during braking, and the air suspension braking data acquisition unit 7022 is used to acquire the vehicle's braking deceleration, suspension height before and during braking, and air spring pressure value before and during braking.

[0175] The braking test data calculation module 703 is used to calculate the axle load change during the emergency braking test based on the suspension stiffness characteristics and the suspension characteristic pressure height data, and to calculate the center of gravity height and center of gravity height change during braking based on the axle load, axle load change, the wheelbase of the two axles, the braking deceleration, the static radius of the tire, the load-deformation characteristics of the tire, the axle load, and the suspension characteristic pressure height data;

[0176] Optionally, the braking test data calculation module 703 includes an axle load variation calculation unit 7031, a center of gravity height calculation unit 7032 during braking, and a center of gravity height variation calculation unit 7034; wherein the axle load variation calculation unit 7031 is used to calculate the axle load variation in the emergency braking test based on the suspension stiffness characteristics and the suspension characteristic pressure height data. Specifically, when the front suspension of the vehicle is a leaf spring suspension, the axle load variation in the emergency braking test is calculated based on the leaf spring stiffness of the suspension and the suspension height before and during braking. The formula is as follows:

[0177] △M=(h f1 -h f2 )*K lf / g;

[0178] Among them, △M is the change of axle load, h f1 is the front suspension height before braking, h f2 is the front suspension height during braking, g is the acceleration due to gravity, K lf is the leaf spring stiffness of the front suspension;

[0179] Alternatively, the axle load change during the emergency brake test can be calculated using the following formula:

[0180] △M=(h r2 -h r1 )*K lr / g;

[0181] Among them, h r2 is the rear suspension height when braking, h r1 is the rear suspension height before braking, K lr is the leaf spring stiffness of the rear suspension;

[0182] When the vehicle's front suspension is an air suspension, the axle load change during the emergency braking test is calculated based on the relationship between the air spring height and load, the suspension height before and during braking, and the air spring pressure before and during braking. Specifically, the loads of the air spring before and during braking are obtained based on the suspension height before and during braking, the air spring pressure before and during braking, and the relationship between the air spring height and load. Then, the axle load change during the emergency braking test is calculated based on the loads of the air spring before and during braking. The formula is as follows:

[0183] △M=(F f2 -F f1 ) / g;

[0184] Among them, F f2 is the load of the front suspension air spring during braking, F f1 It is the load of the front suspension air spring before braking;

[0185] Alternatively, the axle load change during the emergency brake test can be calculated using the following formula:

[0186] △M=(F r1 -F r2 ) / g;

[0187] Among them, F r1 is the load of the rear suspension air spring before braking, F r2 It is the load of the rear suspension air spring during braking;

[0188] The center of gravity height calculation unit 7032 during braking is used to calculate the center of gravity height during braking based on the axle load, axle load change, the wheelbase of the two axles, and the braking deceleration, specifically:

[0189] According to the wheelbase and axle load of the two axles, calculate the distance from the center of gravity of the vehicle to the front axle. The formula is as follows:

[0190] L f =M r *L / M f ;

[0191] Among them, L f is the distance from the center of gravity of the vehicle to the front axle, L is the wheelbase of the two axles, M f is the front axle load, M r is the rear axle load;

[0192] The center of gravity height during braking is calculated based on the axle load, the distance from the vehicle's center of gravity to the front axle, the change in axle load, the wheelbase of the two axles, and the braking deceleration. The formula is as follows:

[0193] h=[(M f +M r )*g*Lf -(M r -△M)*g*L] / [(M f +M r )*a];

[0194] Where h is the height of the center of gravity during braking, a is the braking deceleration, △M is the change in axle load, and g is the acceleration due to gravity;

[0195] The center of gravity height change calculation unit 7033 is used to calculate the center of gravity height change based on the static radius of the tire, the load deformation characteristics of the tire, the wheelbase of the two axles, the axle load and the suspension characteristic pressure height data, specifically:

[0196] The deformation of the tire radius is obtained based on the axle load, the static radius of the tire, and the load deformation characteristics of the tire. The height change of the tire and suspension is then calculated based on the deformation of the tire radius before and during braking and the suspension height before and during braking.

[0197] Calculate the height change of the tire and suspension of the front axle using the following formula;

[0198] △h f =(△r tf2 -△r tf1 )+(h f1 -h f2 );

[0199] Among them, △h f is the height change of the tire and suspension of the front axle, △r tf2 is the deformation of the front suspension tire radius during braking, △r tf1 is the deformation of the front suspension tire radius before braking, h f1 is the front suspension height before braking, h f2 is the front suspension height when braking;

[0200] Calculate the height change of the tire and suspension of the rear axle using the following formula:

[0201] △h r =(△r tr2 -△r tr1 )+(h r2 -h r1 );

[0202] Among them, △h r is the height change of the tire and suspension of the rear axle, △r tr2 is the deformation of the rear suspension tire radius during braking, △r tr1 is the deformation of the rear suspension tire radius before braking, h r2 is the rear suspension height when braking, h r1 is the rear suspension height before braking;

[0203] According to the distance from the center of gravity of the vehicle to the front axle and the wheelbase of the two axles, calculate the distance from the center of gravity of the vehicle to the rear axle. The formula is as follows:

[0204] L r =LL f ;

[0205] Among them, L r is the distance from the center of gravity of the vehicle to the rear axle, L is the wheelbase of the two axles, L f is the distance from the vehicle's center of gravity to the front axle;

[0206] The height change of the center of gravity is calculated based on the height change of the tire and suspension of the front axle, the height change of the tire and suspension of the rear axle, and the distance from the center of gravity of the vehicle to the rear axle. The formula is as follows:

[0207] △h=L r *(△h f +△h r ) / L-△h r ;

[0208] Where △h is the change in the center of gravity height.

[0209] The vehicle center of gravity height calculation module 704 is used to calculate the center of gravity height of the vehicle according to the center of gravity height and the center of gravity height change during braking.

[0210] In this embodiment, the heights of the front and rear suspensions change during the emergency braking test. Therefore, the center of gravity height during braking calculated above needs to be corrected to obtain the center of gravity height of the entire vehicle under static conditions. The center of gravity height during braking and the change in center of gravity height are summed to calculate the center of gravity height of the entire vehicle.

[0211] This embodiment utilizes an emergency braking test with the vehicle positioned on a horizontal surface to induce pitch. The center of gravity height during braking is calculated using data such as axle load change and braking deceleration. The center of gravity height change during emergency braking is calculated using data such as axle load, suspension characteristic pressure height, and tire load-deformation characteristics. The center of gravity height during braking is corrected using this change in center of gravity height, allowing for accurate calculation of the vehicle's static center of gravity height. This method is applicable to two-axle vehicles, as well as vehicles that can be simplified to be considered two-axle vehicles. It calculates axle load transfer during a stable pitch, accurately obtaining the vehicle's center of gravity height. It is also applicable to any vehicle load condition, whether empty or fully loaded, and can calculate the vehicle's center of gravity height.

[0212] The specific embodiments described above further illustrate the objectives, technical solutions, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A method for measuring the height of the center of gravity of a vehicle, characterized in that: include: Obtain the static radius of the vehicle's tires, the load-deformation characteristics of the tires, the suspension stiffness characteristics, the axle load, and the wheelbase of the two axles; When the vehicle is on a horizontal surface and undergoes an emergency braking test, obtaining braking deceleration, and suspension characteristic pressure height data before and during braking of the vehicle; calculating an axle load change in the emergency braking test according to the suspension stiffness characteristic and the suspension characteristic pressure height data; Calculating the center of gravity height and the center of gravity height change during braking based on the axle load, the axle load change, the wheelbase of the two axles, the braking deceleration, the static radius of the tire, the load-deformation characteristics of the tire, and the suspension characteristic pressure height data; Calculating the center of gravity height of the vehicle according to the center of gravity height during braking and the center of gravity height change; The center of gravity height and the center of gravity height change during braking are calculated based on the axle load, the axle load change, the wheelbase of the two axles, the braking deceleration, the static radius of the tire, the load deformation characteristics of the tire, and the suspension characteristic pressure height data, specifically: Calculating the center of gravity height during braking based on the axle load, the axle load change, the wheelbase of the two axles, and the braking deceleration; Calculating the center of gravity height change based on the static radius of the tire, the load-deformation characteristics of the tire, the wheelbase of the two axles, the axle load, and the suspension characteristic pressure height data; The calculation of the center of gravity height during braking according to the axle load, the axle load change, the wheelbase of the two axles, and the braking deceleration is specifically as follows: Calculate the distance from the center of gravity of the vehicle to the front axle based on the wheelbase and axle load of the two axles; The center of gravity height during braking is calculated based on the axle load, the distance from the center of gravity of the vehicle to the front axle, the axle load change, the wheelbase of the two axles, and the braking deceleration. The formula is as follows: h=[(M f +M r )*g*L f -(M r -△M)*g*L] / [(M f +M r )*a]; Wherein, h is the height of the center of gravity during braking, a is the braking deceleration, ΔM is the change in axle load, g is the acceleration due to gravity, and L f is the distance from the center of gravity of the vehicle to the front axle, L is the wheelbase of the two axles, M f is the front axle load, M r is the rear axle load; The calculation of the center of gravity height change according to the static radius of the tire, the load deformation characteristics of the tire, the wheelbase of the two axles, the axle load and the suspension characteristic pressure height data is specifically as follows: Obtaining a deformation of the tire radius based on the axle load, the static radius of the tire, and the load-deformation characteristic of the tire, and then calculating a height change of the tire and the suspension based on the deformation of the tire radius before and during braking and the suspension height before and during braking; Calculate the height change of the tire and suspension of the front axle using the following formula; △h f =(△r tf2 -△r tf1 )+(h f2 -h f1 ); Among them, △h f is the height change of the tire and suspension of the front axle, △r tf2 is the deformation of the front suspension tire radius during braking, △r tf1 is the deformation of the front suspension tire radius before braking, h f1 is the front suspension height before braking, h f2 is the front suspension height when braking; Calculate the height change of the tire and suspension of the rear axle using the following formula: △h r =(△r tr2 -△r tr1 )+(h r2 -h r1 ); Among them, △h r is the height change of the tire and suspension of the rear axle, △r tr2 is the deformation of the rear suspension tire radius during braking, △r tr1 is the deformation of the rear suspension tire radius before braking, h r2 is the rear suspension height during braking, h r1 is the rear suspension height before braking; According to the distance from the center of gravity of the vehicle to the front axle and the wheelbase of the two axles, the distance from the center of gravity of the vehicle to the rear axle is calculated as follows: L r =LL f ; Among them, L r is the distance from the center of gravity of the vehicle to the rear axle, L is the wheelbase of the two axles, L f is the distance from the vehicle's center of gravity to the front axle; The height change of the center of gravity is calculated based on the height change of the tire and suspension of the front axle, the height change of the tire and suspension of the rear axle, and the distance from the center of gravity of the vehicle to the rear axle. The formula is as follows: △h=L r *(△h f +△h r ) / L-△h r ; Wherein, Δh is the change in the height of the center of gravity.

2. The method for measuring the center of gravity height of a vehicle according to claim 1, wherein: The static radius of the tire of the vehicle, the load deformation characteristics of the tire, the suspension stiffness characteristics, the axle load and the wheelbase of the two axles are obtained, wherein the suspension stiffness characteristics are obtained, specifically: When the front suspension of the vehicle is a leaf spring suspension, obtaining the leaf spring stiffness of the suspension; When the front suspension of the vehicle is an air suspension, the relationship between the height and load of the air spring is obtained.

3. The method for measuring the center of gravity height of a vehicle according to claim 2, wherein: When the vehicle is on a horizontal surface and undergoes an emergency braking test, the braking deceleration of the vehicle and the suspension characteristic pressure height data before and during braking are obtained, specifically: When the front suspension of the vehicle is a leaf spring suspension, obtaining the braking deceleration, and the suspension height before and during braking of the vehicle; When the front suspension of the vehicle is an air suspension, the braking deceleration, the suspension height before and during braking, and the air spring pressure values ​​before and during braking of the vehicle are obtained.

4. A vehicle center of gravity height measurement system, characterized in that: The vehicle center of gravity height measurement system includes: a static data acquisition module, a braking test data acquisition module, a braking test data calculation module and a vehicle center of gravity height calculation module; The static data acquisition module is used to obtain the static radius of the tire, the load deformation characteristics of the tire, the suspension stiffness characteristics, the axle load and the wheelbase of the two axles of the vehicle; The braking test data acquisition module is used to acquire the braking deceleration, and the suspension characteristic pressure height data before and during braking of the vehicle when the vehicle is located on a horizontal surface and undergoes an emergency braking test; The braking test data calculation module is used to calculate the axle load change in the emergency braking test based on the suspension stiffness characteristics and the suspension characteristic pressure height data, and to calculate the center of gravity height and the center of gravity height change during braking based on the axle load, the axle load change, the wheelbase of the two axles, the braking deceleration, the static radius of the tire, the load deformation characteristics of the tire, and the suspension characteristic pressure height data; The vehicle center of gravity height calculation module is used to calculate the center of gravity height of the vehicle according to the center of gravity height during braking and the center of gravity height change; The center of gravity height and the center of gravity height change during braking are calculated based on the axle load, the axle load change, the wheelbase of the two axles, the braking deceleration, the static radius of the tire, the load deformation characteristics of the tire, and the suspension characteristic pressure height data, specifically: Calculating the center of gravity height during braking based on the axle load, the axle load change, the wheelbase of the two axles, and the braking deceleration; Calculating the center of gravity height change based on the static radius of the tire, the load-deformation characteristics of the tire, the wheelbase of the two axles, the axle load, and the suspension characteristic pressure height data; The calculation of the center of gravity height during braking according to the axle load, the axle load change, the wheelbase of the two axles, and the braking deceleration is specifically as follows: Calculate the distance from the center of gravity of the vehicle to the front axle based on the wheelbase and axle load of the two axles; The center of gravity height during braking is calculated based on the axle load, the distance from the center of gravity of the vehicle to the front axle, the axle load change, the wheelbase of the two axles, and the braking deceleration. The formula is as follows: h=[(M f +M r )*g*L f -(M r -△M)*g*L] / [(M f +M r )*a]; Wherein, h is the height of the center of gravity during braking, a is the braking deceleration, ΔM is the change in axle load, g is the acceleration due to gravity, and L f is the distance from the center of gravity of the vehicle to the front axle, L is the wheelbase of the two axles, M f is the front axle load, M r is the rear axle load; The calculation of the center of gravity height change according to the static radius of the tire, the load deformation characteristics of the tire, the wheelbase of the two axles, the axle load and the suspension characteristic pressure height data is specifically as follows: Obtaining a deformation of the tire radius based on the axle load, the static radius of the tire, and the load-deformation characteristic of the tire, and then calculating a height change of the tire and the suspension based on the deformation of the tire radius before and during braking and the suspension height before and during braking; Calculate the height change of the tire and suspension of the front axle using the following formula; △h f =(△r tf2 -△r tf1 )+(h f2 -h f1 ); Among them, △h f is the height change of the tire and suspension of the front axle, △r tf2 is the deformation of the front suspension tire radius during braking, △r tf1 is the deformation of the front suspension tire radius before braking, h f1 is the front suspension height before braking, h f2 is the front suspension height when braking; Calculate the height change of the tire and suspension of the rear axle using the following formula: △h r =(△r tr2 -△r tr1 )+(h r2 -h r1 ); Among them, △h r is the height change of the tire and suspension of the rear axle, △r tr2 is the deformation of the rear suspension tire radius during braking, △r tr1 is the deformation of the rear suspension tire radius before braking, h r2 is the rear suspension height during braking, h r1 is the rear suspension height before braking; According to the distance from the center of gravity of the vehicle to the front axle and the wheelbase of the two axles, the distance from the center of gravity of the vehicle to the rear axle is calculated as follows: L r =LL f ; Among them, L r is the distance from the center of gravity of the vehicle to the rear axle, L is the wheelbase of the two axles, L f is the distance from the vehicle's center of gravity to the front axle; The height change of the center of gravity is calculated based on the height change of the tire and suspension of the front axle, the height change of the tire and suspension of the rear axle, and the distance from the center of gravity of the vehicle to the rear axle. The formula is as follows: △h=L r *(△h f +△h r ) / L-△h r ; Wherein, Δh is the change in the height of the center of gravity.

5. A vehicle center of gravity height measurement system as claimed in claim 4, characterized in that: The static data acquisition module includes a leaf spring suspension static data acquisition unit and an air suspension static data acquisition unit, wherein the leaf spring suspension static data acquisition unit is used to acquire the static radius of the tire, the load-deformation characteristics of the tire, the axle load, the wheelbase of the two axles, and the leaf spring stiffness of the suspension; the air suspension static data acquisition unit is used to acquire the static radius of the tire, the load-deformation characteristics of the tire, the axle load, the wheelbase of the two axles, and the relationship between the height and load of the air spring; The braking test data acquisition module includes a leaf spring suspension braking data acquisition unit and an air suspension braking data acquisition unit, wherein the leaf spring suspension braking data acquisition unit is used to acquire the vehicle's braking deceleration, suspension height before and during braking, and the air suspension braking data acquisition unit is used to acquire the vehicle's braking deceleration, suspension height before and during braking, and air spring pressure value before and during braking.

Images