Leveling method of electronic control air suspension and electronic control air suspension system

Abstract

The invention discloses a leveling method of an electronic control air suspension and an electronic control air suspension system, which are characterized in that a height sensor and an acceleration sensor are used for carrying out combined measurement on the height of a vehicle body, a Kalman filter is used for determining the weight of the height of each sensor, and obtained data are used as the calculated height, so that the measurement precision of the height of the vehicle body is improved; according to the difference value between the measured height data and the target height data, whether the adjustment condition is met or not is judged, and when it is judged that the adjustment condition is met, the electromagnetic valve is controlled through the PID controller and the fuzzy controller so as to adjust the height of the suspension. By processing the measurement data of the two sensors, the accuracy of the vehicle body height measurement data is effectively improved, the problem of leveling errors caused by inaccurate height data measurement in the prior art is solved, the limitation of traditional leveling precision is broken through, the suspension height control with higher precision is realized, and the vehicle body height measurement accuracy is improved. And the reliability of the system and the riding comfort are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronically controlled air suspensions, and relates to a high-precision leveling method for electronically controlled air suspensions, in particular to a leveling method for electronically controlled air suspensions and an electronically controlled air suspension system. Background Art

[0002] With the continuous advancement of automotive technology, electronically controlled air suspension systems (ECAS) have garnered widespread attention for their ability to automatically adjust vehicle height based on road conditions and load, improving vehicle stability and ride comfort. Generally, vehicle height control systems are divided into mechanical and electronic control systems. Height control sensors, installed near the suspension (e.g., four sensors located in the front, rear, left, and right), detect vehicle height (displacement of the vehicle's suspension system) and convert this information into an electronic signal, which is then input into the ECU. This seamless integration of electronic control and the air suspension system maximizes the performance of the air suspension system. The ECU collects and analyzes sensor information such as vehicle height, steering angle, acceleration, and road condition predictions to control the suspension actuators. The system's control functions typically include vehicle height adjustment and damping force control, which enhance vehicle handling stability. These functions suppress changes in vehicle posture during sharp cornering, rapid acceleration, and emergency braking. Spring rate control also involves varying spring rate to adjust the suspension to meet sporty or comfortable requirements.

[0003] In the automatic adjustment of vehicle height by the electronically controlled air suspension system, the acquisition of a stable and reliable height signal is a crucial link, which directly affects the control performance of the vehicle height. In the existing control system, the height sensor is the detection part, which is installed between the vehicle body and the suspension. It is used to detect changes in the vehicle height above a certain wheel or axle and provide the vehicle height information to the computer. The computer controls the suspension height through the integrated information. However, due to the signal fluctuations of the sensor itself, the measurement data of the height sensor objectively has measurement errors, which affects the stability of the vehicle height control. The traditional electronically controlled air suspension system uses a single height sensor signal as height information, which makes the leveling accuracy limited and the reliability needs to be improved to meet the smooth driving of the car. Therefore, in response to the above problems and technical requirements, it is necessary to improve the existing electronically controlled air suspension height control method. Summary of the Invention

[0004] Typically, vehicles equipped with air-adjustable suspensions are equipped with distance sensors near the front and rear wheels. These sensors' output signals are used by the onboard computer to determine vehicle height changes. The computer then controls the air compressor and exhaust valves to automatically compress or extend the springs, thereby lowering or raising the chassis clearance to improve vehicle stability at high speeds or maneuverability in complex road conditions. Current leveling methods for electronically controlled air suspensions rely on distance sensors (also known as height sensors), resulting in a need for improved accuracy. To address these issues, the present invention provides an electronically controlled air suspension leveling method and system. This method, which incorporates acceleration parameters for collaborative calculations with conventional height sensors, improves the accuracy of vehicle height measurement data, accelerates system response, and enables more accurate and reliable leveling.

[0005] The technical solution adopted by the present invention to solve its technical problem is: A leveling method for an electronically controlled air suspension comprises the following steps: (1) Obtain the height data Z measured by the height sensor of the vehicle at the same time height , acceleration compensation height data Z accel ; Z accel =a(A accel -A ref )+Z0 Among them, A accel is the real-time measurement value of the vertical acceleration sensor (unit: m / s 2 ); A ref is the baseline acceleration, extracted by low-pass filtering; a is the calibration coefficient; Z0 is the target suspension height; (2) Determine Z using Kalman filter height The weight W height 、Z accel The weight W accel , according to formula (2), the suspension height Z is calculated. Formula (2) is: Z=W height ·Z height +W accel ·Z accel , W height +W accel =1; (3) Determine whether the adjustment conditions are met based on the difference between the calculated suspension height and the target suspension height; (4) When the adjustment conditions are met, the solenoid valve is controlled by the PID controller and the fuzzy controller to adjust the suspension height.

[0006] In the present invention, the leveling method of the electronically controlled air suspension is performed while the vehicle is in motion.

[0007] In the present invention, A ref The reference acceleration (low-frequency component) is obtained through low-pass filtering. When low-pass filtering, the cutoff frequency is 0.1Hz to 1Hz.

[0008] In the present invention, acceleration refers to the vertical acceleration of the vehicle. In the prior art, automobile vertical acceleration sensors are primarily used to monitor the vertical motion state of the vehicle, with their core functions encompassing three major functional modules: slope detection, shock absorber damping adjustment, and safety control. In an electronically controlled suspension system, the vertical acceleration sensor senses the vibration frequency of the vehicle body in real time, and the system adjusts the shock absorber damping force accordingly, primarily to reduce damping to minimize impact and to increase damping to suppress body roll during high-speed cornering. This present invention proposes for the first time the relationship between vehicle vertical acceleration and vehicle height, and introduces height compensation corresponding to the vehicle's vertical acceleration into the leveling process of the electronically controlled air suspension. Unexpectedly, this innovative technical approach significantly improves the leveling effect of the electronically controlled air suspension. Compared to conventional electronically controlled air suspension leveling methods that rely solely on height sensors, the present invention not only achieves instantaneous leveling within milliseconds, but also achieves significantly better leveling results than the prior art, surpassing expectations.

[0009] In the present invention, the calibration method of a is as follows: the vehicle is fixed on the vibration table, the frequency, time and amplitude are input, the vertical acceleration data and the vehicle height change data are obtained, and a is calculated according to formula (1), which is: a=△Z / A a , △Z is the average value of height change, A a is the average vertical acceleration The present invention discloses a corresponding relationship between the vertical acceleration of a vehicle and the change in vehicle height, which can be obtained by calibrating the vehicle. The calibration steps are as follows: in a standard test field, apply frequency, time and amplitude to the vehicle placed on a vibration table, and obtain A a The corresponding vehicle height change is △Z, and then according to a=△Z / A a Calibration a; during the input time, △Z is the average value of the height change, A a is the vertical acceleration.

[0010] In the technical solution of the present invention, as a common sense, when the vehicle is in the stretched state, a is a positive value (positive number), and when the vehicle is in the retracted state, a is a negative value (negative number). The vehicle is in the stretched state or the retracted (sinking) state according to the height data Z measured by the height sensor height The target suspension height can be judged conventionally. In the stretched state, the height data Z measured by the height sensor is height Greater than the target suspension height, the height data Z measured by the retracted height sensor height is less than the target suspension height. Therefore, when the height data Z measured by the height sensor isheight When the height data Z measured by the height sensor is greater than the target suspension height, a is a positive number; height When the suspension height is less than the target height, a is negative. For a specific vehicle, the absolute value of a is the same whether the vehicle is in the extended or contracted state, but the direction is different, resulting in positive or negative values.

[0011] In the present invention, as common sense, the test site is a conventional vehicle factory test site. As common sense, vehicles of the same specifications will undergo theoretical tests to obtain relevant parameters as standard data for factory vehicles. The vehicle is fixed on a vibration table, and the frequency, time and amplitude are input to obtain vertical acceleration data and vehicle height change data. This is a conventional technology. A is obtained based on the acceleration curve within the input time. a , obtain △Z according to the vehicle height curve within the input time. Specifically, it is a conventional technology. When a vehicle leaves the factory, it will routinely undergo a vibration table simulation test to obtain some parameters under the vibration state. The present invention uses the existing standard experimental method to obtain the acceleration curve and height curve, and then conventionally takes the average value of the peak and trough as A a , and calculate △Z, thereby obtaining a proposed for the first time in the present invention.

[0012] The present invention proposes a formula for the relationship between the change in vehicle vertical acceleration and vehicle height, realizing the incorporation of acceleration factors into air suspension adjustment for the first time. This overcomes the technical prejudice of the prior art that leveling of electronically controlled air suspension can only be performed using a height sensor. In particular, the method of the present invention achieves significant technical progress that exceeds people's imagination.

[0013] In the present invention, according to the Kalman gain K k Determine Z accel 、Z height The weight of Z height The weight W height 、Z accel The weight W accel , according to formula (2), the suspension height Z is calculated as conventional technology, and is obtained according to the conventional formula.

[0014] In the present invention, the Kalman filter is used to determine the height sensor Z height The weight W height , acceleration sensor corresponding to Z accel The weight W accel The following steps are involved: (1) According to formula K k =P k|k-1 H T (HP k|k-1 H T +R k ) -1 Calculate Z separately heightThe Kalman gain K height 、Z accel The Kalman gain K accel , where P k|k-1 is the covariance matrix of the predicted state at the kth moment, H is the measurement matrix, R k is the covariance matrix of the measurement noise at the kth moment; (2) According to the Kalman gain K k Determine Z accel 、Z height The weight of height =K height / (K height +K accel ), W accel =1-W height .

[0015] In the present invention, the Kalman gain is obtained by conventional Kalman filtering, which is a mathematical algorithm for estimating the state of a dynamic system. The state prediction is as follows:

[0016] The covariance prediction is as follows:

[0017] The residual covariance is calculated as follows:

[0018] The Kalman gain is as follows:

[0019] The status update is as follows:

[0020] The covariance is updated as follows:

[0021] In the present invention, when the difference between the calculated suspension height and the target suspension height exceeds a preset height difference, it is determined that the adjustment condition is met.

[0022] Specifically, a target suspension height error band is set, and the calculated suspension height during the adjustment process is obtained. When the difference between the calculated suspension height and the target suspension height exceeds the target suspension height error band, the suspension height is automatically adjusted; when the difference between the calculated suspension height and the target suspension height is within the target suspension height error band, the suspension height is not adjusted.

[0023] As is common sense, the target suspension height is the suspension height when the vehicle is parked and then started. It can be set by the driver and passengers themselves or by the vehicle's built-in central control system. The height error band is set by those skilled in the art based on the technical ideas disclosed in this invention and can be written into the ECAS controller by conventional methods before or after leaving the factory.

[0024] In the present invention, the height error band is within ±0.5 cm, preferably within ±0.4 cm, more preferably within ±0.3 cm, more preferably within ±0.2 cm, and even more preferably within ±0.1 cm. As an example, on a flat road, the comfort value of the suspension height (i.e., the target suspension height) of a conventional four-wheeled electric vehicle is 40 cm, and the height error band is set to ±0.5 cm. When the difference between the calculated suspension height and the target suspension height (40 cm) exceeds ±0.5 cm, the suspension height is adjusted until the difference between the calculated suspension height and the target suspension height (40 cm) is within ±0.5 cm.

[0025] The present invention discloses an electronically controlled air suspension system, comprising a height sensor, an acceleration sensor, a solenoid valve, an air compressor, an air spring and a suspension height control unit; the suspension height control unit executes the leveling method of the electronically controlled air suspension.

[0026] The present invention discloses a vehicle including an electronically controlled air suspension system, which includes the electronically controlled air suspension system described above.

[0027] The invention discloses the application of the above-mentioned leveling method of the electronically controlled air suspension in adjusting the height of the automobile suspension.

[0028] In the present invention, the height (suspension height) is the distance between the vehicle frame and the axle. As is common knowledge, a height sensor is usually mounted on the vehicle body structure (such as a longitudinal beam) at one end and on the suspension lower arm at the other end to measure the real-time distance between the two.

[0029] Improving the accuracy and reliability of height measurement is a key issue that needs to be addressed in current vehicle control technology. This invention uses a height sensor and an acceleration sensor to measure vehicle height. A Kalman filter is used to determine the weights of these two sensors to calculate suspension height. This improves the accuracy of vehicle height measurement data, enabling more precise leveling.

[0030] In the present invention, the height sensor is a laser ranging sensor, an ultrasonic ranging sensor, an infrared height sensor or a radar altimeter; the acceleration sensor is a conventional vehicle vertical acceleration sensor; in actual application, it is selected according to needs and does not affect the understanding of the technical effects of the present invention by those skilled in the art.

[0031] In the present invention, a target suspension height error band is set to monitor the calculated suspension height during the adjustment process. When the difference between the calculated and target suspension heights exceeds the target suspension height error band, the suspension height is automatically adjusted. Specifically, when the difference between the calculated and target suspension heights exceeds the upper limit of the error band, the solenoid valve is controlled to discharge the gas in the air spring; when the difference between the calculated and target suspension heights falls below the lower limit of the error band, the solenoid valve is controlled to charge the air spring with high-pressure gas generated by the air compressor.

[0032] The present invention sets a target suspension height error band, allowing the system to fluctuate within a certain range to reduce frequent minor adjustments and extend the service life of components. When the difference between the calculated suspension height and the target suspension height exceeds the target suspension height error band, the system can quickly make adjustments to ensure that the vehicle can maintain the optimal posture under different operating conditions.

[0033] In the present invention, suspension height adjustment is achieved by controlling a solenoid valve using a PID controller and a fuzzy controller. The method of controlling the solenoid valve using a PID controller and a fuzzy controller is conventional and does not affect the understanding of the present invention by those skilled in the art. The solenoid valve controls the amount of air within the air spring bladder (inflation or deflation), causing the spring to extend or compress, thereby raising or lowering the chassis. This is prior art. In short, the fuzzy controller calculates PID control parameters based on the calculated suspension height and preset fuzzy rules. The PID controller then calculates control data based on the control parameters and outputs control data to the solenoid valve, which controls the solenoid valve to inflate or deflate the air spring, achieving suspension height adjustment.

[0034] In the present invention, the height sensor is used to measure the real-time height of the vehicle body and feed it back to the suspension height control unit; the acceleration sensor is used to measure the real-time acceleration of the vehicle and feed it back to the suspension height control unit; the pressure sensor is used to measure the real-time air pressure in the air spring and feed it back to the suspension height control unit; the solenoid valve is used to control the flow direction of the air, that is, inflation or deflation; the air compressor is used to provide high-pressure gas; the air spring responds to the control of the suspension height control unit to achieve suspension height adjustment; the suspension height control unit is used to receive signals from various sensors and control the action of the solenoid valve according to conventional preset logic and algorithms, which is existing technology.

[0035] Furthermore, the number of the height sensors is at least one, and the number of the acceleration sensors is one or more; preferably, the number of the height sensors is 1 to 10, and the number of the acceleration sensor is one.

[0036] In the present invention, each air spring is equipped with a corresponding height sensor and a built-in pressure sensor. As is common knowledge, an electronically controlled air suspension system includes at least one air spring; preferably, an electronically controlled air suspension system is equipped with an air spring for each wheel of the vehicle. For a four-wheeled vehicle, an electronically controlled air suspension system includes at least four air springs, corresponding to four height sensors and four pressure sensors. In addition, a vertical acceleration sensor is installed directly below the center of mass of the vehicle body (usually in the center channel of the chassis). This position is least affected by pitch / roll motion and can reflect pure vertical acceleration. This is existing technology.

[0037] Due to the application of the above technical solution, the beneficial effects of the present invention are: first, the present invention introduces vehicle acceleration information into the air suspension height measurement for the first time, and solves the problem of inaccurate data measurement in the prior art by utilizing two sensors to perform combined measurement of the vehicle body height and adopting Kalman gain to process the data, thereby significantly improving the accuracy and reliability of the vehicle body height measurement data, thereby achieving higher-precision suspension leveling; second, a target suspension height error band is set to monitor the calculated suspension height during the adjustment process, allowing the system to fluctuate within a certain range, reducing frequent minor adjustments, extending the service life of components, and improving the response speed of the system. Height deviations can be detected and corrected in a timely manner, which is beneficial for responding to sudden load changes or uneven road conditions, to ensure that the vehicle can maintain the best posture under different working conditions, and improve the safety and comfort of riding; third, the present invention uses dual sensors for redundant measurement, which improves the reliability of system operation and ensures the normal operation of the suspension leveling function. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The figure is a schematic diagram of a method for leveling an electronically controlled air suspension while a vehicle is in motion according to the present invention.

[0039] Figure 2 This is the fitting curve of the relationship between the vehicle's vertical acceleration and height change in Example 3. DETAILED DESCRIPTION

[0040] As common sense, the air suspension system uses the signal from the height sensor. The on-board computer will determine the change in vehicle height (the distance between the frame and the axle), and then control the air compressor and exhaust valve to automatically compress or extend the spring, thereby lowering or raising the ground clearance of the chassis to increase the stability of the vehicle at high speeds or the passability in complex road conditions.

[0041] In existing public technology, vertical acceleration sensors are primarily used for shock absorber damping adjustment (e.g., to suppress roll and optimize comfort). Typical applications include reducing damping to reduce impact when going over speed bumps and increasing damping to suppress body roll during high-speed cornering. There are no reports of their direct use for suspension height calculation or adjustment. Existing leveling solutions rely on height sensors (such as laser / ultrasonic rangefinders) or air pressure sensors to indirectly infer height. This invention is innovative, establishing for the first time a dynamic mapping relationship between vertical acceleration and suspension height change. Its physical essence is that acceleration can be used to obtain displacement changes, which are then superimposed on static height to achieve dynamic compensation.

[0042] The existing technology relies on height sensors to perform leveling of electronically controlled air suspensions, and its leveling accuracy needs to be improved. The creativity of the present invention lies in proposing to incorporate the vertical acceleration data measured by the vertical acceleration sensor into the leveling of the electronically controlled air suspension. For the first time, the compensation data Z is calculated based on the vertical acceleration data measured by the vertical acceleration sensor in the leveling of the electronically controlled air suspension. accel By calculating and allocating weights through conventional Kalman gain, accurate measurement of the vehicle body height at the current moment is achieved. This is the key and basis for the leveling of the electronically controlled air suspension. Under this precise height data, the existing PID controller and fuzzy controller (fuzzy PID control) are used to control the solenoid valve to adjust the suspension height and improve the leveling effect.

[0043] In the present invention, the height data Z measured by the height sensor at the same time is obtained. height , vertical acceleration data measured by the vertical acceleration sensor, and compensation data Z calculated based on the vertical acceleration data accel , according to the Kalman gain K k Determine Z accel 、Z height The weights and the height 、W accel The calculation of the suspension height Z is a conventional technique and can be written into the ECU in a conventional manner.

[0044] The present invention is further described below with reference to specific embodiments. The specific components involved are existing products, and the connection and use methods between the specific components are conventional technologies. A second-order Butterworth low-pass filter is selected as the low-pass filter, which is a conventional choice in the field. Example 1

[0045] A leveling method for an electronically controlled air suspension comprises the following steps: (1) The vehicle is in driving state, and the height data Z measured by the height sensor at the same time is obtained height , vertical acceleration data measured by the vertical acceleration sensor, and compensation data Z calculated based on the vertical acceleration data measured by the vertical acceleration sensor accel ; (2) Using Kalman filter to determine the Z of the height sensor height Weight W height , Z of the accelerometer accel Weight W accel , according to the height data Z height , compensation data Z accel , get the calculated suspension height, the calculation formula for the suspension height is Z=W height ·Z height +W accel ·Z accel , W height +W accel =1; (3) Determine whether the adjustment conditions are met based on the difference between the calculated suspension height and the target suspension height; (4) When the difference between the calculated suspension height and the target suspension height exceeds the preset height difference, the solenoid valve is controlled by the PID controller and the fuzzy controller to adjust the suspension height.

[0046] Set the target suspension height error band and monitor the calculated suspension height during the adjustment process. When the difference between the calculated suspension height and the target suspension height is higher than the upper limit of the error band, control the solenoid valve to discharge the gas in the air spring; when the difference between the calculated suspension height and the target suspension height is lower than the lower limit of the error band, control the solenoid valve to fill the high-pressure gas generated by the air compressor into the air spring.

[0047] In step (1), Z accel =a(A accel -A ref )+Z0; Among them, A accel is the real-time measurement value of the vertical acceleration sensor (unit: m / s 2 ); A ref is the baseline acceleration, extracted by low-pass filtering; a is the calibration coefficient; Z0 is the target suspension height.

[0048] The calibration steps are as follows: In a standard test field, apply frequency, time and amplitude to the vehicle placed on the vibration table, and obtain A a The corresponding vehicle height change is △Z, and then according to a=△Z / A a Calibration a; during the input time, △Z is the average value of the height change, A a is the vertical acceleration.

[0049] Height data Z measured by the height sensor height When it is greater than the target suspension height, a is a positive number; Height data Z measured by the height sensorheight When it is less than the target suspension height, a is a negative number; For a specific car, whether the car is in a stretched state or a contracted state, the absolute value of a is the same, but the direction is different, so there are positive and negative numbers.

[0050] In step (2), the Kalman filter is based on the conventional formula K k =P k|k-1 H T (HP k|k-1 H T +R k ) -1 Calculate the Z of the height sensor separately height Kalman gain K height , Z of vertical acceleration sensor accel Kalman gain K accel , where P k|k-1 is the covariance matrix of the predicted state at the kth moment, H is the measurement matrix, R k is the covariance matrix of the measurement noise at the kth moment; then according to the Kalman gain K k Determine Z height and Z accel The weight, W height =K height / (K height +K accel ), W accel =1-W height .

[0051] As a common sense, in actual use, P k|k-1 =AP k-1 A T +Q k , where A is the state transfer matrix, P k-1 is the covariance matrix of the state variables at the k-1th moment, Q k is the covariance matrix of the system noise at the kth moment, R k is the covariance matrix of the measurement noise at the kth moment; the kth moment is the current moment, and the k-1th moment is the previous moment.

[0052] In the present invention, the Kalman gain is obtained by conventional Kalman filtering, which is a mathematical algorithm for estimating the state of a dynamic system. The state prediction is as follows:

[0053] The covariance prediction is as follows:

[0054] The residual covariance is calculated as follows:

[0055] The Kalman gain is as follows:

[0056] The status update is as follows:

[0057] The covariance is updated as follows:

[0058] In the present invention, the method of controlling the solenoid valve by the PID controller and the fuzzy controller is a conventional technology. The fuzzy controller calculates the control parameters of the PID based on the calculated suspension height and preset fuzzy rules. The PID controller calculates the control data of the output solenoid valve based on the control parameters, and controls the solenoid valve to inflate and deflate the air spring to adjust the suspension height, which does not affect the understanding of the present invention by those skilled in the art.

[0059] In this embodiment, the height data is the distance between the vehicle frame and the vehicle axle. Example 2

[0060] An electronically controlled air suspension system includes a height sensor, a vertical acceleration sensor, a solenoid valve, an air compressor, an air spring (with its own pressure sensor), and a suspension height control unit. The suspension height control unit implements the electronically controlled air suspension leveling method described in Example 1. These components are all existing products, and their installation and use follow conventional techniques.

[0061] As is common sense, an electronically controlled air suspension system is equipped with an air spring for each wheel of the vehicle (each air spring is independently adjustable). In this embodiment, a height sensor and a pressure sensor are correspondingly provided for each air spring. The height sensor uses a laser ranging sensor; and a vertical acceleration sensor is provided, which is located directly below the center of mass of the vehicle body. This is existing technology. Example 3

[0062] A vehicle comprises the electronically controlled air suspension system of the second embodiment; the vehicle is a four-wheel medium-sized SUV and is provided with four height sensors and one acceleration sensor. Comparative Example 1

[0063] Based on the first embodiment, the vertical acceleration compensation data Z accel It does not participate in the calculation of suspension height. The calculated suspension height is the height data Z measured by the laser ranging sensor. heightThis method is a conventional leveling method for electronically controlled air suspensions. The difference between the calculated and target suspension heights determines whether the adjustment conditions are met. If the difference exceeds a preset height difference, the PID controller and fuzzy controller control the solenoid valve to adjust the suspension height. Comparative Example 2

[0064] Based on the first embodiment, the height data Z measured by the laser ranging sensor height Does not participate in the calculation of suspension height. The calculated suspension height is the vertical acceleration compensation data Z accel ; According to the difference between the calculated suspension height and the target suspension height, determine whether the adjustment conditions are met; when the difference between the calculated suspension height and the target suspension height exceeds the preset height difference, the solenoid valve is controlled by the PID controller and the fuzzy controller to adjust the suspension height. Application Examples

[0065] Example 3 Vehicle vertical acceleration and compensation data Z accel The calibration steps for a are as follows: (1) Test conditions: Vehicle model: mid-size SUV (curb mass 1850kg, wheelbase 2860mm); Equipment: six-degree-of-freedom vibration table (accuracy ±0.5), laser displacement sensor (accuracy ±0.1mm), vertical acceleration sensor (accuracy ±0.1mm); Status: Vehicle fully loaded (gross mass 2300kg), tire pressure standard (2.5Bar).

[0066] (2) Calibration method: In a conventional test field, the vehicle wheels are fixed on the vibration table (the height is the initial height at this time), and the data of the laser displacement sensor (height sensor) and the vertical acceleration sensor are input into the computer through the data line; the frequency (1Hz), time (3 minutes) and amplitude are input into the vibration table control panel in a conventional manner, and the vehicle height curve and vertical acceleration curve within 3 minutes are obtained through the computer in a conventional manner; Take the sum of the peak vertical accelerations and average it to get the average acceleration A within 3 minutes a , take the peak vehicle height minus the initial vehicle height as the height difference, and add and average all height differences to get the average height difference (height change △Z) within 3 minutes; Referring to the above method, change the amplitude to obtain multiple groups of average acceleration and average height difference; Fit the average acceleration and average height difference of each group to obtain Figure 2 , has a good linear relationship, according to a=△Z / A a Calibrate a to 0.05 s 2, considering the sensor accuracy, a is taken to two decimal places; at this time, the vehicle is stretched; Referring to the above method, when the vehicle shrinks and changes, a is -0.05 s 2 .

[0067] The present invention proposes vertical acceleration and compensation data Z accel Formula, the conventionally obtained A a , △Z conversion, realizing the inclusion of acceleration factors in air suspension adjustment for the first time.

[0068] Control logic: Target height: H target =40cm; Allowable error band: ±0.2cm; Single round adjustment threshold: |H wheel -H target |>0.2cm; The vehicle suspension height (i.e., target suspension height) is 40 cm, and the height error band is set to ±0.2 cm. When the difference between the calculated suspension height and the target suspension height (40 cm) exceeds ±0.2 cm, the suspension height is adjusted until the difference between the calculated suspension height and the target suspension height (40 cm) is within ±0.2 cm.

[0069] Reasonable analysis: Differences within the allowable error band (such as 39.9cm / 40.1cm) can adapt to road unevenness (such as unilateral bumps) and improve comfort.

[0070] Verification experiment According to conventional methods, on a test road with continuous standard speed bumps (starting from 100m on a flat road, with a speed bump spacing of 2m and a height of 5cm, and 20 speed bumps), the vehicle of Example 3 was driven at a normal speed of 50km / h through the speed bumps at a constant speed, forming the experimental group.

[0071] After the experiment is completed, the vehicle vertical acceleration compensation data Z of Example 3 is accel Change to not participate in the calculation of suspension height, that is, the calculated suspension height is the height data Z measured by the laser ranging sensor height , corresponding to the proportion 1, the vehicle is driven at a normal speed of 50km / h through the speed bump at a constant speed to conduct a parallel experiment.

[0072] After the experiment is completed, the height data Z measured by the laser ranging sensor of the vehicle in Example 3 is height Change to not participate in the calculation of suspension height, that is, according to the vehicle vertical acceleration compensation data Z accel Perform leveling to correspond to the second ratio, and then drive the vehicle at a normal speed of 50km / h through the speed bump at a constant speed to conduct a parallel experiment.

[0073] In each experiment, a measuring cup (500 mL) filled with 300 ml of water was fixed on the roof of the car, and an egg basket containing 30 eggs was placed on the back seat.

[0074] The remaining water in the measuring cup and the broken eggs of the vehicles of Example 3, Comparative Example 1, and Comparative Example 2 after passing over the speed bump are shown in Table 1, and the maximum and minimum values ​​of the vertical acceleration are shown in Table 2.

[0075] Table 1 Remaining water in the measuring cup

[0076] Table 2 Vertical acceleration (m / s 2 )'s highest and lowest values

[0077] When the vehicle contacts the speed bump at a speed of 50 km / h, vibration occurs, resulting in instantaneous height change. Under the impact of the speed bump, the height sensor is disturbed by mechanical vibration. The weight W assigned by the conventional Kalman filter is used in the present invention. height 、W accel , thus obtaining the calculated height. The dual height parameters are introduced for leveling, which solves the problem that the existing technology relies solely on the height sensor for leveling accuracy, which needs to be improved. It can be seen that only using the vertical acceleration parameter cannot effectively level the device, the accuracy is low, and some eggs are broken. However, combining the vertical acceleration with the existing height sensor and the collaborative calculation of the two bring unexpected technological progress: In the first experiment (i.e., Example 3, Z height and Z accel The remaining water in the vehicle measuring cup involved in the calculation of the suspension height is more than that in other experiments, and is particularly superior to the experiment corresponding to the existing method for adjusting the height of the air suspension (ie, comparative example 1, Z accel The difference between the highest and lowest vertical accelerations of the experimental vehicle of the present invention is small, indicating that the vehicle of the present invention has a small bump amplitude, high stability and comfort, and a good leveling method, which is especially important for air suspension leveling with an adjustment time of milliseconds.

[0078] In the present invention, acceleration refers to the vertical acceleration of the vehicle. In the prior art, automobile vertical acceleration sensors are primarily used to monitor the vertical motion state of the vehicle, with their core functions encompassing three major functional modules: slope detection, shock absorber damping adjustment, and safety control. In an electronically controlled suspension system, the vertical acceleration sensor senses the vibration frequency of the vehicle body in real time, and the system adjusts the shock absorber damping force accordingly, primarily to reduce damping to minimize impact and to increase damping to suppress body roll during high-speed cornering. This present invention proposes for the first time the relationship between vehicle vertical acceleration and vehicle height, and introduces height compensation corresponding to the vehicle's vertical acceleration into the leveling process of the electronically controlled air suspension. Unexpectedly, this innovative technical approach significantly improves the leveling effect of the electronically controlled air suspension. Compared to conventional electronically controlled air suspension leveling methods that rely solely on height sensors, the present invention not only achieves instantaneous leveling within milliseconds, but also achieves significantly better leveling results than the prior art, surpassing expectations.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A leveling method for an electronically controlled air suspension, characterized in that: The following steps are involved: (1) Obtain the height data Z measured by the height sensor of the vehicle at the same time height , acceleration compensation height data Z accel ; Z accel =a(A accel -A ref )+Z0; Among them, A accel It is the real-time measurement value of the vertical acceleration sensor; A ref is the baseline acceleration, extracted by low-pass filtering; a is the calibration coefficient; Z0 is the target suspension height; (2) Determine Z using Kalman filter height The weight W height 、Z accel The weight W accel , according to formula (2), the suspension height Z is calculated. Formula (2) is: Z=W height ·Z height + W accel ·Z accel , W height +W accel =1; (3) Determine whether the adjustment conditions are met based on the difference between the calculated suspension height and the target suspension height; (4) When the adjustment conditions are met, the solenoid valve is controlled by the PID controller and the fuzzy controller to adjust the suspension height.

2. The leveling method of the electronically controlled air suspension according to claim 1, characterized in that: In step (1), the leveling method of the electronically controlled air suspension is performed while the vehicle is in motion; during low-pass filtering, the cutoff frequency is 0.1 Hz to 1 Hz.

3. The leveling method of the electronically controlled air suspension according to claim 1, characterized in that: In step (1), acceleration is the vertical acceleration of the vehicle; the calibration method of a is as follows: the vehicle is fixed on the vibration table, and the frequency, time and amplitude are input to obtain the vertical acceleration data and the vehicle height change data. According to formula (1), a is calculated. Formula (1) is: a = △ Z / A a , △Z is the average value of height change, A a is the average vertical acceleration.

4. The leveling method of the electronically controlled air suspension according to claim 1, characterized in that: Use Kalman filter to determine the weight W of the height sensor height Or the weight W of the accelerometer accel The following steps are involved: According to the formula K k =P k|k-1 H T (HP k|k-1 H T +R k ) -1 Calculate Z separately height The Kalman gain K height 、Z accel The Kalman gain K accel , where P k|k-1 is the covariance matrix of the predicted state at the kth moment, H is the measurement matrix, R k is the covariance matrix of the measurement noise at the kth moment; (2) Determine Z based on Kalman gain height 、Z accel The weight of height =K height / (K height +K accel ), W accel =1-W height .

5. The leveling method of the electronically controlled air suspension according to claim 1, characterized in that: When the difference between the calculated suspension height and the target suspension height exceeds a preset difference, it is determined that the adjustment condition is met.

6. The leveling method of the electronically controlled air suspension according to claim 5, characterized in that: Set the target suspension height error band and obtain the calculated suspension height during the adjustment process; when the difference between the calculated suspension height and the target suspension height exceeds the target suspension height error band, the suspension height is automatically adjusted; when the difference between the calculated suspension height and the target suspension height is within the target suspension height error band, the suspension height is not adjusted.

7. An electronically controlled air suspension system, characterized in that: It comprises a height sensor, an acceleration sensor, a solenoid valve, an air compressor, an air spring and a suspension height control unit; the suspension height control unit executes the leveling method of the electronically controlled air suspension according to any one of claims 1 to 6.

8. The electronically controlled air suspension system according to claim 7, characterized in that: The number of the height sensor is at least one.

9. A vehicle comprising an electronically controlled air suspension system, characterized in that: The electronically controlled air suspension system includes the electronically controlled air suspension system according to claim 7.

10. Application of the leveling method of the electronically controlled air suspension according to claim 1 in adjusting the height of automobile suspension.

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