A whole vehicle unsprung mass measurement method, device, equipment and storage medium

Abstract

The present application relates to the technical field of chassis suspension system testing, and specifically discloses a vehicle unsprung mass measurement method, device, equipment and storage medium, the method comprising: controlling a target vehicle to move vertically up and down at a horizontal plane, the stiffness characteristic of the suspension system of the target vehicle being linear; obtaining spring elasticity and wheel normal pressure of at least two sampling points in the vertical up-and-down movement process of the target vehicle, the wheel normal pressure being the pressure given to the vehicle by the horizontal plane in the vertical direction; determining the mapping relationship between the spring elasticity and the wheel normal pressure based on the obtained spring elasticity and wheel normal pressure; calculating the target wheel normal pressure corresponding to zero spring elasticity according to the mapping relationship, and calculating the unsprung mass according to the target wheel normal pressure. The present application improves the accuracy of unsprung mass measurement.

Description

Technical Field

[0001] This invention relates to the field of chassis suspension system testing technology, specifically to a method, device, equipment, and storage medium for measuring the unsprung mass of a vehicle. Background Technology

[0002] With the development of the automotive industry, China's automotive industry is becoming increasingly mature, and the demands for vehicle performance are also rising. Unsprung weight refers to the weight not supported by the vehicle's suspension system, including tires, wheels, and brakes. Correspondingly, sprung weight refers to the weight supported by the vehicle's suspension system, which constitutes the majority of the vehicle's weight, including the frame, powertrain, transmission, and occupants. It's commonly believed that reducing 1 kg of unsprung weight is equivalent to reducing 15 kg of sprung weight. While these figures may not be entirely accurate, the effect and impact are indeed significant. Therefore, accurately measuring unsprung weight is crucial for a vehicle's stability and handling. Currently, most technologies use simulation models to measure unsprung weight. For example, Chinese patent CN110220578A discloses a simulation measurement method, which places high demands on the accuracy of the whole vehicle model. Poor model accuracy significantly affects the measurement results. Therefore, there is currently no optimal testing method to accurately obtain the whole vehicle's unsprung weight. Summary of the Invention

[0003] In view of this, the present invention provides a method, apparatus, device and storage medium for measuring the unsprung mass of a vehicle, in order to solve the problem of inaccurate measurement of the unsprung mass of a vehicle.

[0004] In a first aspect, the present invention provides a method for measuring the unsprung mass of a vehicle, the method comprising: controlling a target vehicle to move vertically up and down in a horizontal plane, wherein the suspension system stiffness characteristics of the target vehicle are linear; during the vertical up and down movement of the target vehicle, acquiring the spring force and wheel normal force at at least two sampling points, wherein the wheel normal force is the pressure exerted on the wheel by the horizontal plane in the vertical direction; determining a mapping relationship between the spring force and the wheel normal force based on the acquired spring force and the wheel normal force; calculating the target wheel normal force corresponding to when the spring force is zero according to the mapping relationship, and calculating the unsprung mass according to the target wheel normal force.

[0005] According to the aforementioned technical means, the unsprung mass of a vehicle typically exerts pressure on the ground, and the reaction force exerted by the ground on the tire should be the sum of the pressure exerted by the unsprung mass on the ground and the spring force. However, in reality, the spring force cannot be zero. Therefore, in this embodiment of the invention, the target vehicle is placed on a horizontal plane. In particular, the subsequent linear fitting mapping relationship step is only meaningful if the suspension system stiffness characteristics of the target vehicle are linear. Then, the target vehicle is moved up and down using an external device, and at certain times, sensors detect the spring force and wheel normal pressure during the vertical up-and-down movement of the target vehicle, with at least two sampling points. Subsequently, by sampling the spring force and wheel normal force, the mapping relationship between the spring force and wheel normal force can be fitted through numerical calculation. Thus, the value of the spring force is set to 0. Then, the target wheel normal force corresponding to the spring force being equal to 0 is determined by the fitted mapping relationship. The target wheel normal force is equivalent to the pressure exerted on the ground by the unsprung mass. Finally, the unsprung mass of the target vehicle can be accurately determined by the ratio of the target wheel normal force to the gravitational acceleration. Compared with the simulation method, the unsprung mass can be measured directly using a real vehicle with simple operation, which significantly improves the accuracy of unsprung mass measurement.

[0006] In one optional implementation, controlling the target vehicle to move vertically up and down in a horizontal plane includes: controlling the target vehicle to move vertically up and down at a uniform target speed within 1 mm / s to 3 mm / s in a horizontal plane.

[0007] Based on the above technical means, the chassis system generally has system damping, which introduces interference forces that affect the measurement. Therefore, in this embodiment of the invention, the vehicle speed is controlled to be slow enough during reciprocating motion to reduce the impact of system damping.

[0008] In one optional implementation, controlling the target vehicle to move vertically up and down in a horizontal plane further includes: controlling the target vehicle to perform at least three rounds of up-and-down reciprocating motion with a first distance as the single movement distance in a vehicle preparation posture; and controlling the target vehicle to perform at least three rounds of up-and-down reciprocating motion with a second distance as the single movement distance in a vehicle preparation posture.

[0009] Based on the aforementioned technical means, this embodiment of the invention performs measurements for different vertical movement distances. The sampling data for a single movement distance at the first distance is used as the first sample, and the sampling data for a single movement distance at the second distance is used as the second sample, thereby obtaining the spring force and wheel normal force at at least two sampling points. Furthermore, each sampling measurement involves at least three rounds of vertical reciprocating motion. The purpose is to stabilize the control system controlling the vertical movement of the target vehicle in the first two rounds, and to obtain more stable test data by taking data from the third and subsequent rounds, thus reducing sampling data errors.

[0010] In one optional implementation, acquiring the spring force and wheel normal force at at least two sampling points includes: when the target vehicle moves a single distance of a first distance, measuring the first spring force and the first wheel normal force when the target vehicle jumps to a first preset distance at a first target wheel number, wherein the first target wheel number is greater than or equal to 3, and the first preset distance is the distance from the measurement position to the horizontal plane, and the first preset distance is less than the first distance; measuring the second spring force and the second wheel normal force when the target vehicle falls back to the first preset distance at the target wheel number; calculating the average of the first spring force and the second spring force as the first sampling spring force at the first sampling point; and calculating the average of the first wheel normal force and the second wheel normal force as the first sampling spring force at the first sampling point. The first sampling point measures the first sampled wheel normal force; when the target vehicle moves a single distance of the second distance, the third spring force and the third wheel normal force are measured when the target vehicle jumps to the second preset distance at the second target wheel number (greater than or equal to 3), and the second preset distance is the distance from the measurement position to the horizontal plane (less than the second distance); the fourth spring force and the fourth wheel normal force are measured when the target vehicle falls back to the second preset distance at the second target wheel number; the average of the third spring force and the fourth spring force is calculated as the second sampled spring force at the second sampling point; the average of the third wheel normal force and the fourth wheel normal force is calculated as the second sampled wheel normal force at the second sampling point.

[0011] Based on the above technical means, for each sampling, by moving up and down in a small amplitude, two force values ​​corresponding to the upward and downward movements of the preset sampling position are collected, and then the average value is taken. This can reduce the influence of internal friction of the chassis and improve the measurement accuracy of spring force and wheel positive pressure.

[0012] In one optional implementation, determining the mapping relationship between the spring force and the wheel normal force based on the acquired spring force and wheel normal force includes: calculating a first difference between a first sampled spring force and a second sampled spring force, wherein the first sampled spring force is the spring force collected at a first sampling point, and the second sampled spring force is the spring force collected at a second sampling point; calculating a second difference between a first sampled wheel normal force and a second sampled wheel normal force, wherein the first sampled wheel normal force is the wheel normal force collected at a first sampling point, and the second sampled wheel normal force is the wheel normal force collected at a second sampling point; and determining the first difference and the second difference. The ratio coefficient between the values; a spring force straight line is fitted using the first sampled spring force and the second sampled spring force, the spring force straight line is used to represent the relationship between the lifting posture and the spring force; a wheel normal pressure straight line is fitted using the first sampled wheel normal pressure and the second sampled wheel normal pressure, the wheel normal pressure straight line is used to represent the relationship between the lifting posture and the wheel normal pressure; a mapping relationship is created based on the target wheel normal pressure parameter and the ratio coefficient to match the spring force straight line and the wheel normal pressure straight line, the ratio coefficient is used to adjust the slope matching of the two lines, and the target wheel normal pressure parameter is used to adjust the position matching of the two lines.

[0013] In one optional implementation, the target wheel normal pressure is calculated according to the mapping relationship when the spring force is zero, including: obtaining the third sampled spring force and the third sampled wheel normal pressure at the same sampling point; inputting the third sampled spring force and the third sampled wheel normal pressure into the mapping relationship; and outputting the parameter value of the target wheel normal pressure parameter in the mapping relationship to obtain the target wheel normal pressure.

[0014] Based on the aforementioned technical means, by acquiring at least two sets of spring force and wheel normal pressure, the first difference between the two sets of spring force is calculated, and then the second difference between the two sets of wheel normal pressure is calculated. The linear relationship between spring force and wheel normal pressure can be obtained by the ratio between the first difference and the second difference. Thus, the mapping relationship between spring force and wheel normal pressure can be determined by the ratio coefficient between the first difference and the second difference. Based on this, the spring force at any sampling time and the ratio coefficient are multiplied or divided, and the target wheel normal pressure when the spring force is 0 is added to the result. This result should be equal to the wheel normal pressure at the corresponding sampling time. Then, by solving the equation with the target wheel normal pressure as an unknown, the target wheel normal pressure can be accurately obtained.

[0015] In an alternative implementation, before controlling the target vehicle to move vertically up and down in a horizontal plane, the method further includes: releasing stress at the bushing and chassis connection of the target vehicle; and releasing tire stress of the target vehicle through a wheel stress relief device.

[0016] According to the above technical means, by setting a stress relief device at the tire, the influence of the horizontal force at the tire on the vertical pressure measurement value can be further reduced. In addition, this embodiment takes into account that the stiffness characteristics of the bushing are nonlinear, and it is necessary to reduce the influence of the nonlinear characteristics of the bushing stiffness. In this way, by releasing the stress at the chassis connection, the influence of the parasitic stiffness generated by the bushing is reduced, and the accuracy of unsprung mass measurement is further improved.

[0017] Secondly, the present invention provides a vehicle unsprung mass measurement device, comprising: a motion control module for controlling a target vehicle to move vertically up and down in a horizontal plane, wherein the suspension system stiffness characteristics of the target vehicle are linear; a data acquisition module for acquiring spring force and wheel normal force at at least two sampling points during the vertical up and down movement of the target vehicle, wherein the wheel normal force is the pressure exerted on the wheel by the horizontal plane in the vertical direction; a mapping module for determining a mapping relationship between the spring force and the wheel normal force based on the acquired spring force and the wheel normal force; and a measurement module for calculating the target wheel normal force corresponding to when the spring force is zero according to the mapping relationship, and calculating the unsprung mass according to the target wheel normal force.

[0018] Thirdly, the present invention provides a computer device, comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to perform the method described in the first aspect or any corresponding embodiment thereof.

[0019] Fourthly, the present invention provides a computer-readable storage medium storing computer instructions for causing a computer to perform the method described in the first aspect or any corresponding embodiment thereof.

[0020] The technical solution provided by this invention has the following advantages:

[0021] (1) Typically, the unsprung mass of a vehicle exerts pressure on the ground, and the reaction force exerted by the ground on the tire should be the sum of the pressure exerted by the unsprung mass on the ground and the spring force. However, in reality, the spring force cannot be zero. Therefore, in this embodiment of the invention, a target vehicle is placed on a horizontal plane and moved up and down by an external device. Then, at certain times, sensors detect the spring force and wheel normal pressure during the vertical up and down movement of the target vehicle, with at least two sampling points. In particular, the subsequent linear fitting mapping relationship is meaningful only if the stiffness characteristics of the target vehicle's suspension system are linear. Subsequently, by sampling the spring force and wheel normal force, the mapping relationship between the spring force and wheel normal force can be fitted through numerical calculation. Thus, the value of the spring force is set to 0. Then, the target wheel normal force corresponding to the spring force being equal to 0 is determined by the fitted mapping relationship. The target wheel normal force is equivalent to the pressure exerted on the ground by the unsprung mass. Finally, the unsprung mass of the target vehicle can be accurately determined by the ratio of the target wheel normal force to the gravitational acceleration. Compared with the simulation method, the unsprung mass can be measured directly using a real vehicle with simple operation, which significantly improves the accuracy of unsprung mass measurement.

[0022] (2) Chassis systems generally have system damping, which introduces interference forces that affect the measurement. Therefore, in this embodiment of the invention, the vehicle speed is controlled to be slow enough during reciprocating motion to reduce the influence of system damping.

[0023] (3) In this embodiment of the invention, measurements are performed for different vertical movement distances. The sampling data of a single movement distance at the first distance is used as the first sample, and the sampling data of a single movement distance at the second distance is used as the second sample, thereby obtaining the spring force and wheel normal pressure at at least two sampling points. Furthermore, each sampling measurement involves at least three rounds of vertical reciprocating motion. The purpose is to stabilize the control system that controls the vertical movement of the target vehicle in the first two rounds, and to obtain more stable test data by taking data from the third round and above, thus reducing the error of the sampling data.

[0024] (4) Considering that internal friction of the chassis system will affect the test results, in order to eliminate the influence of internal friction, this embodiment collects two force values ​​corresponding to the upward and downward movement of the preset sampling position for each sampling by small-amplitude up-and-down reciprocating motion, and then takes the average value, which can reduce the influence of internal friction and improve the measurement accuracy of spring force and wheel positive pressure.

[0025] (5) In this embodiment, by obtaining at least two sets of spring force and wheel normal pressure, the first difference between the two sets of spring force is calculated, and then the second difference between the two sets of wheel normal pressure is calculated. The linear relationship between spring force and wheel normal pressure can be obtained by the ratio between the first difference and the second difference. Thus, the ratio coefficient between the first difference and the second difference can be used as the mapping relationship between spring force and wheel normal pressure. Based on this, the spring force at any sampling time and the ratio coefficient are multiplied or divided, and the target wheel normal pressure when the spring force is 0 is added. The result should be equal to the wheel normal pressure at the corresponding sampling time. Then, the target wheel normal pressure can be accurately obtained by solving the equation with the target wheel normal pressure as an unknown.

[0026] (6) By setting a stress relief device at the tire, the influence of the horizontal force at the tire on the vertical pressure measurement value can be further reduced. In addition, this embodiment takes into account that the stiffness characteristics of the bushing are nonlinear, and it is necessary to reduce the influence of the nonlinear characteristics of the bushing stiffness. Thus, by releasing the stress at the chassis connection, the influence of the parasitic stiffness generated by the bushing is reduced, and the accuracy of the unsprung mass measurement is further improved. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a flowchart illustrating a method for measuring the unsprung mass of a vehicle according to an embodiment of the present invention.

[0029] Figure 2 This is a schematic diagram of the mapping relationship according to an embodiment of the present invention;

[0030] Figure 3 This is a structural block diagram of a vehicle unsprung mass measuring device according to an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] According to an embodiment of the present invention, a method for measuring the unsprung mass of a vehicle is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0034] This embodiment provides a method for measuring the unsprung mass of a vehicle, which can be used in the aforementioned mobile terminals, such as mobile phones, tablet computers, and other computer devices. Figure 1 This is a flowchart of a method for measuring the unsprung mass of a vehicle according to an embodiment of the present invention. The flowchart includes the following steps:

[0035] Step S101: Control the target vehicle to move vertically up and down on the horizontal plane, and the stiffness characteristics of the target vehicle's suspension system are linear.

[0036] Specifically, the unsprung mass of a vehicle typically exerts pressure on the ground. In addition, the ground experiences other pressures from the vehicle chassis, the most significant being the spring force. Therefore, the reaction force exerted by the ground on the tires should be the sum of the pressure exerted by the unsprung mass and the spring force. If the pressure exerted by the unsprung mass on the ground can be accurately measured, the unsprung mass can be calculated using gravitational acceleration. However, in reality, the spring force is rarely zero, making it difficult to measure the pressure exerted by the unsprung mass on the ground when the spring force is zero. Therefore, this invention provides a measurement method combining data acquisition and numerical calculation to accurately measure the unsprung mass.

[0037] Because the measurement method provided in this embodiment of the invention requires the use of the linear relationship between the spring force and the pressure exerted on the ground by the unsprung mass, the solution provided in this embodiment of the invention is applicable to scenarios where the stiffness characteristics of the target vehicle's suspension system are linear. However, it is not applicable to cases where the stiffness characteristics of the target vehicle's suspension system are nonlinear. Whether the stiffness characteristics of a vehicle's suspension system are linear depends on the material, structure, and other characteristics of the vehicle's suspension system, which will not be elaborated upon in this embodiment of the invention.

[0038] First, this embodiment of the invention requires placing the target vehicle on a horizontal surface, and then controlling the target vehicle to move vertically up and down on the horizontal surface. This allows for the measurement of the changing spring force and the force on the wheels in the vertical direction on the horizontal surface during the vehicle's up-and-down movement. In this embodiment, the horizontal surface can be the ground or a platform for a lifting device such as a gantry lift. When the vehicle is on the ground, it can be forced to move up and down by clamping the vehicle body. The device for clamping the vehicle body can utilize a K&C test bench. When the vehicle is on the platform of the lifting device, it can be lifted by the lifting device to achieve up-and-down movement at a low speed.

[0039] Step S102: During the vertical up-and-down movement of the target vehicle, acquire the spring force and wheel normal force at at least two sampling points. The wheel normal force is the pressure exerted on the wheel by the horizontal plane in the vertical direction.

[0040] Specifically, in this embodiment of the invention, during the vertical movement of the target vehicle, multiple sets of spring force and wheel normal pressure are collected by sensors. To fit a linear relationship between the spring force and wheel normal pressure, at least two sampling points of spring force and wheel normal pressure are required for numerical fitting calculations. In this embodiment, a force sensor is installed at the tire contact point, and a stress-strain sensor is installed at the spring, thereby detecting the wheel normal pressure and spring force in real time, respectively. Furthermore, before measuring the vertical movement of the vehicle, this embodiment of the invention also requires parameter calibration of the sensors and the measurement platform (lifting device or clamping device) to ensure the accuracy of the measured values ​​from the hardware equipment.

[0041] Step S103: Determine the mapping relationship between the spring force and the wheel normal force based on the obtained spring force and wheel normal force.

[0042] Specifically, after collecting at least two pairs of spring forces and wheel normal pressure through the above steps, a mapping relationship is fitted using any two pairs of spring forces and wheel normal pressure to determine how the wheel normal pressure should change as the spring force changes. That is, when the spring force changes by one amount, the wheel normal pressure should change by another amount in a linear multiple. This correspondence is the mapping relationship between spring force and wheel normal pressure.

[0043] Step S104: Calculate the target wheel normal force when the spring force is zero according to the mapping relationship, and calculate the unsprung mass according to the target wheel normal force.

[0044] Specifically, based on the mapping relationship determined by the above steps, the spring force is directly assigned a value of 0. Then, the target wheel normal pressure corresponding to the spring force being 0 is determined by the fitted mapping relationship. This is equivalent to calculating the target wheel normal pressure as the pressure exerted on the ground by the unsprung mass alone, since G = mg. Finally, the unsprung mass m of the target vehicle can be accurately determined by the ratio of the target wheel normal pressure G to the gravitational acceleration g. Compared with the simulation method, this embodiment of the invention can directly measure the unsprung mass by performing simple operations on a real vehicle, which significantly improves the accuracy of unsprung mass measurement.

[0045] In some alternative implementations, step S101 includes:

[0046] Step a1: Control the target vehicle to move vertically up and down at a uniform speed within the target speed range of 1mm / s to 3mm / s on the horizontal plane.

[0047] Specifically, the chassis system of a vehicle generally has system damping. In addition to the spring force, the system damping also introduces interference forces that affect the measurement in the direction perpendicular to the horizontal plane. Therefore, in this embodiment of the invention, the vehicle's reciprocating speed is controlled to be slow enough, preferably with a target speed within 1 mm / s to 3 mm / s. For example, the lifting device reciprocates at a speed of 1 mm / s, which can significantly reduce the impact of system damping on the accuracy of measuring spring force and wheel normal pressure.

[0048] In some optional embodiments, step S101 above further includes:

[0049] Step b1: With the vehicle in a ready position, control the target vehicle to perform at least 3 rounds of up-and-down reciprocating motion with the first distance as the single movement distance;

[0050] Step b2: With the vehicle in a ready position, control the target vehicle to perform at least 3 rounds of up-and-down reciprocating motion with the second distance as the single movement distance.

[0051] Specifically, in this embodiment of the invention, two pairs of spring forces and wheel normal pressures are collected in two different scenarios to make the collected data more flexible. By using the spring forces and wheel normal pressures collected in the two scenarios to perform subsequent fitting and mapping relationships, the accuracy of the mapping relationship can be further improved.

[0052] The first scenario involves controlling the target vehicle in a ready-to-go position, moving it at least three times in a single motion, with a first distance as the unit of movement. For example, if the first distance is 10mm, the vehicle is controlled to move upwards by 10mm at a speed of 1mm / s, then downwards by 10mm, repeating this motion three times. The spring force and wheel pressure are collected during this process.

[0053] The second scenario involves controlling the target vehicle in a ready-to-go position, moving it at least three times in a single motion, with a second distance as the unit of distance. For example, if the second distance is 25mm, the vehicle is controlled to move upwards by 25mm at a speed of 1mm / s, then downwards by 25mm, repeating this motion three times. The spring force and wheel pressure are collected during this process.

[0054] In this embodiment of the invention, the purpose of controlling the vehicle to reciprocate at least 3 times is to collect data in later rounds. This is because the lifting device may be unstable in the first few rounds, resulting in unstable lifting and lowering speeds and larger errors in the data collected in the first few rounds. Collecting data in later rounds can reduce the error in the collected data and maintain the stability of the data.

[0055] Based on this, in some optional embodiments, step S102 above includes:

[0056] Step c1: When the target vehicle moves a single distance at the first distance, the first spring force and the first wheel normal force are measured when the target vehicle jumps to the first preset distance at the first target wheel number. The first target wheel number is greater than or equal to 3. The first preset distance is the distance from the measurement position to the horizontal plane. The first preset distance is less than the first distance.

[0057] Step c2: Measure the second spring force and the second wheel normal force when the target vehicle falls back to the first preset distance at the target wheel number.

[0058] Step c3: Calculate the average value of the first spring force and the second spring force, and use it as the first sampled spring force at the first sampling point;

[0059] Step c4: Calculate the average of the normal force of the first wheel and the normal force of the second wheel, and use it as the normal force of the first sampled wheel at the first sampling point;

[0060] Step c5: When the target vehicle moves a single distance at the second distance, the third spring force and the third wheel normal force are measured when the target vehicle jumps to the second preset distance at the second target wheel number. The second target wheel number is greater than or equal to 3, and the second preset distance is the distance from the measurement position to the horizontal plane. The second preset distance is less than the second distance.

[0061] Step c6: Measure the fourth spring force and the fourth wheel normal force when the target vehicle falls back to the second preset distance at the second target wheel number;

[0062] Step c7: Calculate the average value of the third spring force and the fourth spring force, and use it as the second sampled spring force at the second sampling point;

[0063] Step c8: Calculate the average value of the normal pressure of the third wheel and the normal pressure of the fourth wheel, and use it as the normal pressure of the second sampled wheel at the second sampling point.

[0064] Specifically, in this embodiment of the invention, in addition to sampling in two scenarios, sampling is also performed twice in each scenario when rising and falling back to the same position, and the average value is taken as the sampled spring force and wheel normal pressure. This method collects two force values ​​corresponding to the upward and downward movement of the preset sampling position by small-amplitude up-and-down reciprocating motion, and then takes the average value. This can reduce the problem of the influence of the internal friction of the chassis system on the test results, thereby canceling the internal friction in the two directions, and further improving the measurement accuracy of spring force and wheel normal pressure.

[0065] For example: In the first scenario, let the first distance be 10mm. With the vehicle in a ready position, the target vehicle is controlled by the lifting device to move upward by 10mm at a speed of 1mm / s, and then downward by 10mm. This is repeated for 3 rounds. In the third round (the first target round), the first preset distance is selected as 5mm (the distance from the measurement position to the horizontal plane). Two pairs of spring forces and wheel normal pressures are collected at the two moments when the vehicle rises to 5mm and falls back to 5mm. That is, the first set of data is the first spring force f1.1 and the first wheel normal pressure F1.1, and the second set of data is the second spring force f1.2 and the second wheel normal pressure F1.2. Then, the average value of the first spring force and the second spring force, f1 = (f1.1 + f1.2) / 2, is calculated as the first sampling spring force f1 of the first sampling point; the average value of the first wheel normal force and the second wheel normal force, F1 = (F1.1 + F1.2) / 2, is calculated as the first sampling wheel normal force F1 of the first sampling point; in order to eliminate the influence of the friction force in the chassis system on the measurement data.

[0066] Similarly, in the second scenario, assuming the second distance is 25mm, with the vehicle in a ready-to-go posture, the target vehicle is controlled by the lifting device to move upwards by 25mm at a speed of 1mm / s, and then downwards by 25mm, repeating this cycle 3 times. In the third cycle (the second target cycle number), the second preset distance is selected, assuming it is 8mm (the distance from the measurement position to the horizontal plane). Two pairs of spring forces and wheel normal pressures are collected at the two moments when the vehicle rises to 8mm and falls back to 8mm. That is, in the current scenario, the first set of data is the third spring force f2.1 and the third wheel normal pressure F2.1, and the second set of data is the fourth spring force f2.2 and the fourth wheel normal pressure F2.2. Then, the average value of the third spring force and the fourth spring force, f2 = (f2.1 + f2.2) / 2, is calculated as the second sampling spring force of the second sampling point. Similarly, the average value of the normal force of the third wheel and the normal force of the fourth wheel, F2 = (F2.1 + F2.2) / 2, is calculated as the second sampling wheel normal force F2 of the second sampling point to eliminate the influence of the friction force in the chassis system on the measurement data.

[0067] It should be noted that, in addition to selecting two sampling points in this embodiment, the number of sampling points is not limited to two; more points can be measured, and linear fitting can be used for calculation. However, at least two points are required for linear fitting. Alternatively, instead of directly measuring the force at the spring, the strain at the spring can be measured, and the corresponding spring force can be calculated using the same principle.

[0068] In an optional implementation, step S103 includes:

[0069] Step d1: Calculate the first difference between the spring force of the first sampling point and the spring force of the second sampling point. The spring force of the first sampling point is the spring force collected at the first sampling point, and the spring force of the second sampling point is the spring force collected at the second sampling point.

[0070] Step d2: Calculate the second difference between the normal pressure of the first sampled wheel and the normal pressure of the second sampled wheel. The normal pressure of the first sampled wheel is the normal pressure of the wheel collected at the first sampling point, and the normal pressure of the second sampled wheel is the normal pressure of the wheel collected at the second sampling point.

[0071] Step d3: Determine the ratio coefficient between the first difference and the second difference;

[0072] Step d4: Fit a straight line of spring force using the first sampled spring force and the second sampled spring force. The straight line of spring force is used to represent the relationship between the lifting posture and the change of spring force.

[0073] Step d5: Fit the wheel normal pressure line using the first sampled wheel normal pressure and the second sampled wheel normal pressure. The wheel normal pressure line is used to represent the relationship between the lifting posture and the wheel normal pressure.

[0074] Step d6: Create a mapping relationship based on the target wheel normal force parameter and the ratio coefficient to match the spring force line and the wheel normal force line. The ratio coefficient is used to adjust the slope matching of the two lines, and the target wheel normal force parameter is used to adjust the position matching of the two lines.

[0075] Specifically, in this embodiment, at least two sets of spring force and wheel normal force are selected from the spring force and wheel normal force obtained through the aforementioned steps. Then, the first difference between the spring force and the wheel normal force of the two sets are calculated, and the second difference between the wheel normal force and the wheel normal force of the two sets is calculated. The linear relationship between the spring force and the wheel normal force can be obtained in this embodiment through the ratio between the first difference and the second difference. Thus, the mapping relationship between the spring force and the wheel normal force can be determined through the ratio coefficient between the first difference and the second difference.

[0076] For example Figure 2 As shown, when the suspension system stiffness characteristics of the target vehicle are linear, its spring force and wheel normal force also exhibit linear changes. Assuming the first sampled spring force is f1 and the second sampled spring force is f2, a straight line of spring force is fitted in a coordinate system using these two points. The horizontal axis represents the change in the vehicle's lifting posture, indicating the single movement distance during reciprocating motion (in meters), and the vertical axis represents the spring force collected in the corresponding scenario (in nitrogen). Similarly, assuming the first sampled wheel normal force is F1 and the second sampled wheel normal force is F2, a straight line of wheel normal force is fitted in a coordinate system using these two points. The horizontal axis represents the change in the vehicle's lifting posture, indicating the single movement distance during reciprocating motion (in meters), and the vertical axis represents the wheel normal force collected in the corresponding scenario (in nitrogen).

[0077] Where f1 and F1 are data sampled under the same scenario, and f2 and F2 are data sampled under the same scenario, therefore, when the spring force line represents the spring force as 0, the intersection of the wheel normal pressure line at the corresponding position and the vertical axis is the pressure exerted on the horizontal plane by the unsprung mass alone. Therefore, in this embodiment of the invention, the spring force and wheel normal pressure at the same sampling point should satisfy the following formula:

[0078] F = f*a + Fm

[0079] In the formula, F represents the normal force of the wheel at a certain sampling point, f represents the spring force at the same sampling point, a represents a proportionality coefficient, and Fm represents the target wheel normal force parameter, that is, the pressure exerted on the horizontal surface by the unsprung mass alone.

[0080] The above formula can be understood as follows: In order to establish a mapping relationship between spring force and wheel normal pressure, this embodiment aims to match the straight line of spring force with the straight line of wheel normal pressure, so that the two lines can coincide. Therefore, by adjusting the value of spring force through a proportional coefficient, it is equivalent to adjusting the slope of the straight line of spring force to be the same as that of the straight line of wheel normal pressure. However, since the straight line of spring force passes through the origin, it is necessary to move it upward by a corresponding distance according to the target wheel normal pressure in order to match and coincide the two lines.

[0081] Based on this, the target wheel normal force Fm, as the only unknown, is the parameter that needs to be solved subsequently. The spring force parameter f and the wheel normal force parameter F can both be obtained through the sampling values ​​in the aforementioned steps. Therefore, the only value that needs to be determined is the proportionality coefficient a in the above formula. This proportionality coefficient a can be obtained by the ratio between the first difference and the second difference, for example, a = (F1-F2) / (f1-f2) or a = (F2-F1) / (f2-f1). The positive or negative signs of the first and second differences do not affect the proportionality coefficient a, because the negative sign can be eliminated by calculating the ratio.

[0082] Based on this, the mapping relationship created in the embodiments of the present invention is as follows:

[0083] F = f * [(F1 - F2) / (f1 - f2)] + Fm

[0084] Accordingly, in some alternative embodiments, step S104 includes:

[0085] Step e1: Obtain the spring force of the third sampling spring and the normal force of the third sampling wheel at the same sampling point;

[0086] Step e2: Input the mapping relationship between the spring force of the third sampling spring and the normal force of the third sampling wheel;

[0087] Step e3: Output the parameter values ​​of the target wheel normal pressure parameter in the mapping relationship to obtain the target wheel normal pressure.

[0088] Specifically, in this embodiment, the mapping relationship created by the above steps can obtain the third sampling spring force and the third sampling wheel normal pressure of any sampling point from the sampling data. Then, the third sampling spring force and the third sampling wheel normal pressure are substituted into the mapping relationship created by the above steps. In the mapping relationship, the only unknown is the target wheel normal pressure parameter Fm. Thus, the target wheel normal pressure can be calculated by numerical solution. For example, if f1 and F1 are substituted into the above formula, then Fm = F1 - f1 * [(F1 - F2) / (f1 - f2)].

[0089] Furthermore, by using Fm = m*g, the unsprung mass can be accurately measured using the ratio of the target wheel's normal force Fm to the gravitational acceleration g.

[0090] In some optional embodiments, the method for measuring the unsprung mass of a vehicle provided by the present invention further includes the following steps:

[0091] Step f1: Release the stress at the connection between the bushing and chassis of the target vehicle.

[0092] Step f2: Release the tire stress of the target vehicle through the wheel stress relief device.

[0093] Specifically, this embodiment, by incorporating a stress relief device at the tire, can further reduce the influence of horizontal forces on the vertical pressure measurement, thereby improving the accuracy of unsprung mass measurement. The stress relief device can employ a ball bearing structure, such as in a four-wheel alignment machine, or it can utilize an active motion stress relief device, such as a kit for a whole-vehicle K&C testing equipment. The specific structure of the stress relief device is prior art and will not be elaborated upon in this embodiment.

[0094] In addition, this embodiment takes into account that the stiffness characteristics of the bushing are nonlinear, and it is necessary to reduce the influence of the nonlinear characteristics of the bushing stiffness. In this way, by releasing the stress at the chassis connection (relaxing the torque at the chassis connection point), the influence of the parasitic stiffness generated by the bushing is reduced, and the accuracy of unsprung mass measurement is further improved.

[0095] In addition, in this embodiment of the invention, the position of the prepared posture near the horizontal plane is selected as the data acquisition point, and the attitude interval at different acquisition points should not be too large, which can further enhance the linearity of the system stiffness and improve the accuracy of unsprung mass measurement.

[0096] This embodiment also provides a vehicle unsprung mass measuring device, which is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0097] This embodiment provides a device for measuring the unsprung mass of a vehicle, such as... Figure 3 As shown, it includes:

[0098] The motion control module 301 is used to control the vertical up-and-down movement of the target vehicle in the horizontal plane. The suspension system stiffness characteristics of the target vehicle are linear. For details, please refer to the relevant description of step S101 in the above method embodiment, which will not be repeated here.

[0099] The data acquisition module 302 is used to acquire the spring force and wheel normal force at at least two sampling points during the vertical up-and-down movement of the target vehicle. The wheel normal force is the pressure exerted on the vehicle by the horizontal plane in the vertical direction. For details, please refer to the relevant description of step S102 in the above method embodiment, which will not be repeated here.

[0100] The mapping module 303 is used to determine the mapping relationship between the spring force and the wheel normal force based on the acquired spring force and wheel normal force. For details, please refer to the relevant description of step S103 in the above method embodiment, which will not be repeated here.

[0101] The measurement module 304 is used to calculate the target wheel normal force when the spring force is zero according to the mapping relationship, and then calculate the unsprung mass based on the target wheel normal force. For details, please refer to the relevant description of step S104 in the above method embodiment, which will not be repeated here.

[0102] In some alternative implementations, the motion control module 301 includes:

[0103] The speed control unit is used to control the target vehicle to move vertically up and down at a constant target speed within the range of 1 mm / s to 3 mm / s on the horizontal plane.

[0104] The first scenario control unit is used to control the target vehicle to perform at least three rounds of up-and-down reciprocating motion with a first distance as the single movement distance when the vehicle is in a ready position.

[0105] The second scenario control unit is used to control the target vehicle to perform at least three rounds of up-and-down reciprocating motion with the second distance as the single movement distance when the vehicle is in a ready position.

[0106] In some alternative implementations, the data acquisition module 302 includes:

[0107] A single measurement unit is used to measure the first spring force and the first wheel normal force when the target vehicle jumps to the first preset distance at the first target wheel number when the target vehicle moves to the first preset distance at the first target wheel number. The first target wheel number is greater than or equal to 3, and the first preset distance is the distance from the measurement position to the horizontal plane. The first preset distance is less than the first distance.

[0108] The secondary measurement unit is used to measure the second spring force and the second wheel normal force when the target vehicle falls back to the first preset distance at the target wheel number;

[0109] The first mean value unit is used to calculate the average value of the first spring force and the second spring force, which is used as the first sampled spring force of the first sampling point.

[0110] The second averaging unit is used to calculate the average of the normal force of the first wheel and the normal force of the second wheel, which is used as the first sampled wheel normal force of the first sampling point.

[0111] The three-measurement unit is used to measure the third spring force and the third wheel normal force when the target vehicle jumps to the second preset distance with the second target wheel number as the single movement distance. The second target wheel number is greater than or equal to 3, and the second preset distance is the distance from the measurement position to the horizontal plane. The second preset distance is less than the second distance.

[0112] The four-unit measurement system is used to measure the fourth spring force and the fourth wheel normal force when the target vehicle falls back to the second preset distance at the second target wheel number.

[0113] The third averaging unit is used to calculate the average value of the third spring force and the fourth spring force, which is used as the second sampled spring force of the second sampling point.

[0114] The fourth mean unit is used to calculate the average of the normal pressure of the third wheel and the normal pressure of the fourth wheel, which is used as the normal pressure of the second sampled wheel at the second sampling point.

[0115] In some alternative implementations, the mapping module 303 includes:

[0116] The first difference unit is used to calculate the first difference between the first sampling spring force and the second sampling spring force. The first sampling spring force is the spring force collected at the first sampling point, and the second sampling spring force is the spring force collected at the second sampling point.

[0117] The second difference unit is used to calculate the second difference between the first sampled wheel normal pressure and the second sampled wheel normal pressure. The first sampled wheel normal pressure is the wheel normal pressure collected at the first sampling point, and the second sampled wheel normal pressure is the wheel normal pressure collected at the second sampling point.

[0118] The ratio coefficient unit is used to determine the ratio coefficient between the first difference and the second difference;

[0119] The spring force linear unit is used to fit a spring force linear line using the first sampled spring force and the second sampled spring force. The spring force linear line is used to represent the relationship between the lifting posture and the spring force.

[0120] The wheel normal pressure linear unit is used to fit a wheel normal pressure linear line using the first sampled wheel normal pressure and the second sampled wheel normal pressure. The wheel normal pressure linear line is used to represent the relationship between the lifting posture and the wheel normal pressure.

[0121] The mapping unit is used to create a mapping relationship that matches the spring force line and the wheel normal force line based on the target wheel normal force parameter and the ratio coefficient. The ratio coefficient is used to adjust the slope matching of the two lines, and the target wheel normal force parameter is used to adjust the position matching of the two lines.

[0122] In some alternative implementations, the measurement module 304 includes:

[0123] The data extraction unit is used to obtain the spring force of the third sampling spring and the normal force of the third sampling wheel at the same sampling point;

[0124] The input unit is used to map the relationship between the third sampled spring force and the third sampled wheel normal force.

[0125] The output unit is used to output the parameter value of the target wheel normal pressure parameter in the mapping relationship, so as to obtain the target wheel normal pressure.

[0126] In some optional embodiments, the vehicle unsprung mass measuring device provided in this invention further includes:

[0127] The first stress relief module is used to relieve stress at the connection between the bushing and the chassis of the target vehicle.

[0128] The second stress relief module is used to release tire stress of the target vehicle through the wheel stress relief device.

[0129] Further functional descriptions of the above modules and units are the same as those in the corresponding embodiments described above, and will not be repeated here.

[0130] In this embodiment, the vehicle unsprung mass measuring device is presented in the form of a functional unit. Here, a unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and memory that execute one or more software or fixed programs, and / or other devices that can provide the above functions.

[0131] This invention also provides a computer device having the above-described features. Figure 3 The device shown is for measuring the unsprung mass of the entire vehicle.

[0132] Please see Figure 4 , Figure 4 This is a schematic diagram of the structure of a computer device provided in an optional embodiment of the present invention, such as... Figure 4As shown, the computer device includes one or more processors 10, memory 20, and interfaces for connecting the components, including high-speed interfaces and low-speed interfaces. The components communicate with each other via different buses and can be mounted on a common motherboard or otherwise installed as needed. The processors can process instructions executed within the computer device, including instructions stored in or on memory to display graphical information of a GUI on external input / output devices (such as display devices coupled to the interfaces). In some alternative implementations, multiple processors and / or multiple buses can be used with multiple memories and multiple memory modules, if desired. Similarly, multiple computer devices can be connected, each providing some of the necessary operations (e.g., as a server array, a group of blade servers, or a multiprocessor system). Figure 4 Take a processor 10 as an example.

[0133] Processor 10 may be a central processing unit, a network processor, or a combination thereof. Processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The programmable logic device may be a complex programmable logic device (CAMP), a field-programmable gate array (FPGA), a general-purpose array logic (GPA), or any combination thereof.

[0134] The memory 20 stores instructions executable by at least one processor 10 to cause at least one processor 10 to perform the method shown in the above embodiments.

[0135] The memory 20 may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created based on the use of the computer device. Furthermore, the memory 20 may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some alternative embodiments, the memory 20 may optionally include memory remotely located relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0136] The memory 20 may include volatile memory, such as random access memory; the memory may also include non-volatile memory, such as flash memory, hard disk or solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0137] The computer device also includes a communication interface 30 for communicating with other devices or communication networks.

[0138] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code, which, when accessed and executed by the computer, processor, or hardware, implements the methods shown in the above embodiments.

[0139] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for measuring the unsprung mass of a vehicle, characterized in that, The method includes: The target vehicle is controlled to move vertically up and down in the horizontal plane, and the stiffness characteristics of the suspension system of the target vehicle are linear. During the vertical up-and-down movement of the target vehicle, the spring force and wheel normal force at at least two sampling points are obtained, wherein the wheel normal force is the pressure exerted on the wheel by the horizontal plane in the vertical direction. Determining the mapping relationship between the spring force and the wheel normal force based on the acquired spring force and the wheel normal force; the determination of the mapping relationship between the spring force and the wheel normal force based on the acquired spring force and the wheel normal force includes: calculating a first difference between a first sampled spring force and a second sampled spring force, wherein the first sampled spring force is the spring force collected at a first sampling point and the second sampled spring force is the spring force collected at a second sampling point; calculating a second difference between a first sampled wheel normal force and a second sampled wheel normal force, wherein the first sampled wheel normal force is the wheel normal force collected at a first sampling point and the second sampled wheel normal force is the wheel normal force collected at a second sampling point. Determine the ratio coefficient between the first difference and the second difference; fit a spring force straight line using the first sampled spring force and the second sampled spring force, the spring force straight line representing the relationship between the lifting posture and the spring force; fit a wheel normal pressure straight line using the first sampled wheel normal pressure and the second sampled wheel normal pressure, the wheel normal pressure straight line representing the relationship between the lifting posture and the wheel normal pressure; create a mapping relationship based on the target wheel normal pressure parameter and the ratio coefficient to match the spring force straight line and the wheel normal pressure straight line, the ratio coefficient being used to adjust the slope matching of the two lines, and the target wheel normal pressure parameter being used to adjust the position matching of the two lines; The target wheel normal force is calculated based on the mapping relationship when the spring force is zero, and the unsprung mass is calculated based on the target wheel normal force.

2. The method according to claim 1, characterized in that, The control of the target vehicle to move vertically up and down in the horizontal plane includes: Control the target vehicle to move vertically up and down at a constant target speed within the range of 1 mm / s to 3 mm / s on the horizontal plane.

3. The method according to claim 2, characterized in that, The control of the target vehicle to move vertically up and down in the horizontal plane also includes: With the vehicle in a ready position, the target vehicle is controlled to perform at least 3 rounds of up-and-down reciprocating motion with a first distance as the single movement distance. With the vehicle in a ready position, the target vehicle is controlled to perform at least three rounds of up-and-down reciprocating motion, with the second distance as the single movement distance.

4. The method according to claim 3, characterized in that, During the vertical movement of the target vehicle, acquiring the spring force and wheel normal force at at least two sampling points includes: When the target vehicle moves a single distance at a first distance, the first spring force and the first wheel normal force are measured when the target vehicle jumps to a first preset distance at a first target wheel number. The first target wheel number is greater than or equal to 3, and the first preset distance is the distance from the measurement position to the horizontal plane. The first preset distance is less than the first distance. The second spring force and the second wheel normal force are measured when the target vehicle falls back to the first preset distance at the target number of wheels. Calculate the average value of the first spring force and the second spring force, and use it as the first sampled spring force at the first sampling point; Calculate the average value of the normal force of the first wheel and the normal force of the second wheel, and use it as the first sampled wheel normal force at the first sampling point; When the target vehicle moves a single distance at the second distance, the third spring force and the third wheel normal force are measured when the target vehicle jumps to the second preset distance at the second target wheel number. The second target wheel number is greater than or equal to 3, and the second preset distance is the distance from the measurement position to the horizontal plane. The second preset distance is less than the second distance. The fourth spring force and the fourth wheel normal force are measured when the target vehicle falls back to the second preset distance at the second target wheel number. Calculate the average value of the third spring force and the fourth spring force, and use it as the second sampled spring force at the second sampling point; Calculate the average of the normal pressure of the third wheel and the normal pressure of the fourth wheel, and use it as the normal pressure of the second sampled wheel at the second sampling point.

5. The method according to claim 1 or 4, characterized in that, Calculate the target wheel normal force when the spring force is zero based on the mapping relationship, including: Obtain the spring force of the third sampling spring and the normal force of the third sampling wheel at the same sampling point; The third sampling spring force and the third sampling wheel normal force are input into the mapping relationship; Output the parameter value of the target wheel normal pressure parameter in the mapping relationship to obtain the target wheel normal pressure.

6. The method according to claim 1, characterized in that, Before the controlled target vehicle moves vertically up and down in the horizontal plane, the method further includes: Release the stress at the connection between the bushing and chassis of the target vehicle; The tire stress of the target vehicle is released by a wheel stress relief device.

7. A device for measuring the unsprung mass of a vehicle, characterized in that, The device includes: The motion control module is used to control the vertical up-and-down movement of the target vehicle in the horizontal plane, wherein the stiffness characteristics of the suspension system of the target vehicle are linear. The data acquisition module is used to acquire the spring force and wheel normal force at at least two sampling points during the vertical up-and-down movement of the target vehicle. The wheel normal force is the pressure exerted on the wheel by the horizontal plane in the vertical direction. A mapping module is used to determine the mapping relationship between the spring force and the wheel normal force based on the acquired spring force and the wheel normal force. The mapping module includes: a first difference unit, used to calculate a first difference between a first sampled spring force and a second sampled spring force, wherein the first sampled spring force is the spring force collected at a first sampling point, and the second sampled spring force is the spring force collected at a second sampling point; a second difference unit, used to calculate a second difference between a first sampled wheel normal force and a second sampled wheel normal force, wherein the first sampled wheel normal force is the wheel normal force collected at a first sampling point, and the second sampled wheel normal force is the wheel normal force collected at a second sampling point; and a ratio coefficient unit, used to determine the ratio between the first difference and the second difference. The system includes: a ratio coefficient between the spring force and the target wheel pressure; a spring force linear unit for fitting a spring force linear line using the first sampled spring force and the second sampled spring force, the spring force linear line representing the relationship between the lifting posture and the spring force; a wheel pressure linear unit for fitting a wheel pressure linear line using the first sampled wheel pressure and the second sampled wheel pressure, the wheel pressure linear line representing the relationship between the lifting posture and the wheel pressure; and a mapping unit for creating a mapping relationship between the spring force linear line and the wheel pressure linear line based on the target wheel pressure parameter and the ratio coefficient, the ratio coefficient being used to adjust the slope matching of the two lines, and the target wheel pressure parameter being used to adjust the position matching of the two lines. The measurement module is used to calculate the target wheel normal force when the spring force is zero according to the mapping relationship, and to calculate the unsprung mass according to the target wheel normal force.

8. The apparatus according to claim 7, characterized in that, The motion control module includes: The speed control unit is used to control the target vehicle to move vertically up and down at a constant target speed within the range of 1 mm / s to 3 mm / s on the horizontal plane. The first scenario control unit is used to control the target vehicle to perform at least three rounds of up-and-down reciprocating motion with a first distance as the single movement distance when the vehicle is in a ready position. The second scenario control unit is used to control the target vehicle to perform at least three rounds of up-and-down reciprocating motion with the second distance as the single movement distance when the vehicle is in a ready position.

9. The apparatus according to claim 7, characterized in that, The data acquisition module includes: A single measurement unit is used to measure the first spring force and the first wheel normal force when the target vehicle jumps to a first preset distance at a first target wheel number when the target vehicle moves a first distance in a single movement. The first target wheel number is greater than or equal to 3, and the first preset distance is the distance from the measurement position to the horizontal plane. The first preset distance is less than the first distance. A secondary measurement unit is used to measure the second spring force and the second wheel normal force when the target vehicle falls back to the first preset distance at the target wheel number; The first averaging unit is used to calculate the average value of the first spring force and the second spring force, which is used as the first sampled spring force of the first sampling point. The second averaging unit is used to calculate the average value of the first wheel normal pressure and the second wheel normal pressure, which is used as the first sampled wheel normal pressure of the first sampling point; The three-measurement unit is used to measure the third spring force and the third wheel normal force when the target vehicle jumps to the second preset distance at the second target wheel number when the target vehicle moves to the second preset distance at the second target wheel number. The second target wheel number is greater than or equal to 3, and the second preset distance is the distance from the measurement position to the horizontal plane. The second preset distance is less than the second distance. The four-measurement unit is used to measure the fourth spring force and the fourth wheel normal force when the target vehicle falls back to the second preset distance at the second target wheel number; The third averaging unit is used to calculate the average value of the third spring force and the fourth spring force, which is used as the second sampled spring force of the second sampling point. The fourth averaging unit is used to calculate the average value of the normal pressure of the third wheel and the normal pressure of the fourth wheel, which is used as the normal pressure of the second sampled wheel at the second sampling point.

10. The apparatus according to claim 7, characterized in that, The measurement module includes: The data extraction unit is used to obtain the spring force of the third sampling spring and the normal force of the third sampling wheel at the same sampling point; The input unit is used to map the relationship between the third sampled spring force and the third sampled wheel normal force. The output unit is used to output the parameter value of the target wheel normal pressure parameter in the mapping relationship, so as to obtain the target wheel normal pressure.

11. The apparatus according to claim 7, characterized in that, Also includes: The first stress relief module is used to relieve stress at the connection between the bushing and the chassis of the target vehicle. The second stress relief module is used to release tire stress of the target vehicle through the wheel stress relief device.

12. A computer device, characterized in that, include: A memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, the processor executing the computer instructions to perform the method of any one of claims 1 to 6.

13. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing a computer to perform the method of any one of claims 1 to 6.

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