An air suspension closed loop control system

Abstract

This invention discloses a closed-loop control system for air suspension, mainly comprising a gyroscope sensor, an acceleration sensor, a CAN bus, a suspension controller, a solenoid valve, and an airbag. The acceleration sensor and gyroscope sensor are located at the vehicle's center of gravity and are connected to the suspension controller via the CAN bus, solenoid valve, and airbag. This invention utilizes sensors such as the acceleration sensor and gyroscope to acquire signals such as acceleration, roll angle, and yaw rate. It features a compact structure, is unaffected by the tolerances of suspension components, and offers high accuracy.

Description

Technical Field

[0001] This invention belongs to the field of vehicle automation control technology, and specifically relates to an air suspension closed-loop control system. Background Technology

[0002] Air suspension is becoming increasingly widely used in commercial vehicles due to its comfort and adjustable ride height. However, traditional air suspension control systems often use height valves, which collect vehicle height signals and manually adjust the vehicle height as needed to change the vehicle's posture. Once the vehicle posture is adjusted, the suspension stiffness is essentially locked because the airbag pressure is constant, and the overall ride comfort does not adjust accordingly to different road conditions.

[0003] During driving, a vehicle may respond differently depending on factors such as road conditions, driver habits, or unexpected situations. However, the vehicle may not adjust accordingly to these responses, resulting in adverse effects such as large road impacts, significant body roll, and poor grip. This can negatively impact the driver's driving experience, lead to driver fatigue during prolonged driving, and even cause serious safety accidents.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide an air suspension closed-loop control system, thereby overcoming the defects in the prior art.

[0006] To achieve the above objectives, the present invention provides an air suspension closed-loop control system, which mainly includes a gyroscope sensor, an acceleration sensor, a CAN bus, a suspension controller, a solenoid valve, and an airbag; the acceleration sensor and the gyroscope sensor are located at the center of gravity of the vehicle, and the gyroscope sensor and the acceleration sensor are connected to the suspension controller via the CAN bus, the solenoid valve, and the airbag.

[0007] Preferably, the above technical solution further includes: a ride comfort function module: based on the acceleration signal from the acceleration sensor, suspension performance parameters, vehicle speed signal, and in conjunction with the suspension controller, the airbag pressure corresponding to the ride comfort is analyzed.

[0008] Roll function module: Based on the vehicle yaw rate and speed signals from the gyroscope sensor, the suspension controller's wheel angle, roll angle, and lateral acceleration signals, and in conjunction with the suspension controller, the airbag pressure corresponding to the roll compensation is analyzed.

[0009] Pitch function module: Based on the constant speed pitch angle signal of the suspension controller, road surface tilt angle, driver driving behavior, pitch angle difference, longitudinal acceleration, and in conjunction with the suspension controller, the airbag pressure corresponding to the pitch compensation is analyzed.

[0010] A control method for a closed-loop air suspension control system is disclosed. Upon vehicle startup, the airbags inflate to their initial state. A gyroscope sensor identifies the vehicle's attitude and verifies the initial state signal by combining it with the vehicle speed signal. As the vehicle moves, the driver performs steering, braking, or other driving operations. The suspension system responds by using acceleration sensors and gyroscope sensors to detect XYZ three-dimensional acceleration signals, three-dimensional vehicle angle signals, and three-dimensional vehicle angular velocity signals in real time. These signals are then verified against the initial signal. Combined with ride comfort, roll, and pitch function modules, road information and driver intentions can be identified. The suspension controller issues adjustment commands to the solenoid valves, and the airbags actively adjust ride comfort, vehicle roll, and vehicle pitch.

[0011] Preferably, in the above technical solution, the active control of ride comfort includes: road surface speed power spectral density:

[0012] Road surface roughness power spectral density:

[0013]

[0014] Where: n0 is the reference space frequency, n0 = 0.1 (m -1 ); This is the Z-axis acceleration signal. For the variance of the acceleration signal, The acceleration spectrum characteristic of the vehicle body is given by u, which is the vehicle speed signal.

[0015] The road surface grade G can be identified based on the power spectral density of road surface roughness. q (n0), combined with the vehicle speed, the appropriate stiffness of the airbag can be determined by calibration. The suspension controller issues adjustment commands to the solenoid valve to improve ride comfort and grip performance.

[0016] Preferably, in the above technical solution, the active body roll control includes: active body roll control; vehicle turning radius: Wheel turning angle:

[0017] Where: ω is the yaw rate signal, and L is the vehicle wheelbase;

[0018] The suspension controller analyzes driving behavior based on the wheel steering angle θ and roll angle signals. If the roll angle signal is consistent with the wheel steering angle, there is a steering action. The suspension controller analyzes the airbag stiffness based on the lateral acceleration signal and calibration methods, compensates for the suspension support force, and controls the body roll.

[0019] Preferably, in the above technical solution, the vehicle body pitch active control includes: pitch angle difference:

[0020] Front axle load increment:

[0021] in: For pitch angle signal, Let m be the root mean square of the pitch angle over a period of time under constant speed, and m be the total mass of the vehicle. The longitudinal acceleration signal is given, where L is the vehicle wheelbase and h is the total wheelbase. g The height of the center of mass;

[0022] The suspension controller analyzes driving behavior based on vehicle pitch angle and longitudinal acceleration signals. If the longitudinal acceleration is in the same direction as the pitch angle and the acceleration exceeds a certain threshold, the airbag pressure adjustment is activated.

[0023] Preferably, in the above technical solution, the suspension controller compares the pitch angle difference. Front axle load increment: Δm f By combining calibration methods, the required compensation air pressure for the airbag is analyzed, and the airbag pressure is adjusted through a solenoid valve to improve driving safety.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1) Traditional air suspension systems generally rely on passive adjustment, operating in an open-loop mode. This invention employs a closed-loop control mode, which allows the suspension parameters to be adjusted to match changes in the external environment.

[0026] 2) Traditional air suspensions obtain height signals through a height valve, and the accuracy of these signals is significantly affected by suspension tolerances. This patent utilizes sensors such as accelerometers and gyroscopes to obtain signals such as acceleration, roll angle, and yaw rate. It features a compact structure, is unaffected by the tolerances of suspension components, and offers high accuracy.

[0027] 3) Traditional air suspension vehicles cannot adjust airbag pressure while driving, resulting in constant suspension stiffness. This invention uses acceleration and velocity signals, combined with suspension amplitude-frequency characteristics, to determine road surface information. The suspension controller adjusts the stiffness by regulating the inflation and deflation of the airbags, thereby improving ride comfort, reducing unsprung mass bounce, and increasing wheel grip.

[0028] 4) Traditional air suspension systems mostly adjust vehicle height using height valve signals, employing passive control. This invention's suspension controller monitors signals such as vehicle roll angle and pitch angle. When these signals exceed a certain threshold, it combines yaw rate and acceleration signals to determine the driver's intention and actively adjusts the airbag pressure, achieving active compensation for vehicle posture and enhancing driving safety. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the air suspension hardware structure;

[0030] Figure 2 This is a schematic diagram illustrating the working principle of the air suspension software system;

[0031] Figure 3 This is a schematic diagram of the air suspension adjustment logic;

[0032] In the diagram: 1. Right front airbag; 2. Left front airbag; 3. Right rear airbag; 4. Left rear airbag; 5. Suspension controller; 6. Accelerometer sensor; 7. Gyroscope sensor; 8. Right front solenoid valve; 9. Left front solenoid valve; 10. Right rear solenoid valve; 11. Left rear solenoid valve. Detailed Implementation

[0033] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0034] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0035] Hardware system architecture principle as follows Figure 1 As shown, the system mainly includes a gyroscope sensor 7, an accelerometer sensor 6, a CAN bus, a suspension controller 5, a right front solenoid valve 8, a left front solenoid valve 9, a right rear solenoid valve 10, a left rear solenoid valve 11, a right front airbag 1, a left front airbag 2, a right rear airbag 3, and a left rear airbag 4, among other air suspension actuators. The accelerometer sensor 6 and the gyroscope sensor 7 are placed at the vehicle's center of gravity, and transmit relevant signals during vehicle operation to the suspension controller 5 via the CAN bus network. Based on these signals, the suspension controller 5 issues adjustment commands to the right front solenoid valve 8, left front solenoid valve 9, right rear solenoid valve 10, and left rear solenoid valve 11 to inflate and deflate the right front airbag 1, left front airbag 2, right rear airbag 3, and left rear airbag 4, thereby achieving stiffness adjustment and body compensation.

[0036] The working principle of the software system is as follows Figure 2As shown, the gyroscope sensor 7 and the accelerometer sensor 6 transmit the three-dimensional acceleration signals, three-dimensional body angle signals, and three-dimensional body angular velocity signals during vehicle operation to the suspension controller 5 via the CAN bus network. Combined with the vehicle speed signal, the suspension controller 5 parses the signal messages according to the communication matrix, identifies the road conditions and driver's operating intentions, and issues adjustment commands to the right front solenoid valve 8, left front solenoid valve 9, right rear solenoid valve 10, and left rear solenoid valve 11 to inflate and deflate the right front airbag 1, left front airbag 2, right rear airbag 3, and left rear airbag 4 to adjust the airbag stiffness. Combined with the real-time vehicle operation signal, the system judges the overall vehicle adjustment effect and achieves vehicle posture compensation.

[0037] The software system can identify and analyze road information and driving operations, such as... Figure 3 As shown, the vehicle is first started, the airbags inflate to their initial state, and the gyroscope sensor 7 identifies the vehicle's attitude, verifying the initial state signal of the vehicle body in conjunction with the vehicle speed signal. Subsequently, the vehicle starts, and the wheels travel on uneven road surfaces. Driver steering, braking, and other operations cause the vehicle body to respond due to the suspension system. Combined with sensors, real-time detection of X, Y, and Z-axis acceleration, three-axis vehicle body angles, and three-axis vehicle body angular velocities is achieved. By verifying these signals against the initial signals and considering the suspension characteristics, road information and driver intentions can be identified. Adjustment commands are then issued to the solenoid valves to achieve active airbag adjustment.

[0038] Smoothness Active Control:

[0039] 1) Road surface velocity power spectral density:

[0040] 2) Power spectral density of road surface roughness:

[0041] Where: n0 is the reference space frequency, n0 = 0.1 (m -1 ); This is the Z-axis acceleration signal. For the variance of the acceleration signal, The acceleration spectrum characteristic of the vehicle body is given by u, which is the vehicle speed signal.

[0042] The road surface grade G can be identified based on the power spectral density of road surface roughness. q (n0), combined with the vehicle speed, the optimal stiffness of the airbag can be determined by calibration. The suspension controller issues adjustment commands to the solenoid valve to improve ride comfort and grip performance.

[0043] Active body roll control:

[0044] 1) Vehicle turning radius:

[0045] 2) Wheel turning angle:

[0046] Where: ω is the yaw rate signal, and L is the vehicle wheelbase;

[0047] The suspension controller analyzes driving behavior based on the wheel steering angle θ and roll angle signals. If the roll angle signal is consistent with the wheel steering angle, there is a steering action. The suspension controller analyzes the optimal stiffness of the airbag based on the lateral acceleration signal and calibration methods, compensates for the suspension support force, and controls the body roll.

[0048] Active vehicle pitch control:

[0049] 1) Pitch angle difference:

[0050] 2) Front axle load increment:

[0051] in: For pitch angle signal, Let m be the root mean square of the pitch angle over a period of time under constant speed, and m be the total mass of the vehicle. The longitudinal acceleration signal is given, where L is the vehicle wheelbase and h is the total wheelbase. g The height of the center of mass.

[0052] The suspension controller analyzes driving behavior based on vehicle pitch angle and longitudinal acceleration signals. If the longitudinal acceleration is in the same direction as the pitch angle and exceeds a certain threshold, it activates airbag pressure adjustment. The suspension controller compares the pitch angle difference... Front axle load increment: Δm f By combining calibration methods, the required compensation air pressure for the airbag is analyzed, and the airbag pressure is adjusted through a solenoid valve to improve driving safety.

[0053] The software system has three functions, which are used for analyzing and adjusting the ride comfort, roll, and pitch signals respectively.

[0054] Ride comfort module: Accelerometers continuously record acceleration signals over a period of time. Combined with suspension performance parameters and vehicle speed, the suspension controller analyzes the acceleration variance and calculates the power spectral density of the road surface to assess road roughness. Based on road roughness and vehicle speed signals, calibration methods can be used to determine the corresponding airbag pressure for ride comfort.

[0055] Road surface velocity power spectral density formula:

[0056] Roll function module: A gyroscope sensor detects the vehicle's yaw rate. Combined with the vehicle speed signal, the suspension controller analyzes the wheel angle. Simultaneously, combined with roll angle and lateral acceleration signals, the suspension controller verifies the consistency of the signals to determine whether the vehicle is steering. When the roll angle exceeds a certain threshold, based on the roll angle, vehicle speed, and other signals, calibration methods can be used to determine the airbag pressure corresponding to roll compensation.

[0057] Vehicle turning radius formula: Wheel turning angle formula:

[0058] Pitch function module: The suspension controller analyzes the road surface inclination angle based on the pitch angle signal during constant speed descent. When the acceleration signal exceeds a certain threshold, it verifies the consistency between the acceleration signal and the pitch angle difference. If the two signals show consistent trends, it identifies the driver's driving behavior. Simultaneously, based on the pitch angle difference, longitudinal acceleration, and other signals, it uses calibration methods to analyze the airbag pressure corresponding to pitch compensation.

[0059] Three-way adjustment signal priority verification: When all three functional modules issue adjustment signals, the priority of the signals is verified, with the roll signal priority > pitch signal priority > ride comfort signal priority. If a signal is missing or remains unchanged, the signal verification is not referenced.

[0060] When a functional module detects a missing signal during signal verification, a corresponding functional warning message will pop up based on the scope of the signal's impact.

[0061] Fault warning code 1 Smoothness signal NOK Fault warning code 2 Tilt signal NOK Fault warning code 3 Pitch signal NOK .

[0062] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A control method of an air suspension closed loop control system, characterized by: When the vehicle starts, the airbag inflates to its initial state, and the gyroscope sensor (7) identifies the vehicle posture and verifies the initial state signal of the vehicle body in conjunction with the vehicle speed signal. When the vehicle starts, the driver performs steering, braking or other driving operations, and the suspension system responds. The XYZ three-dimensional acceleration signal, the three-dimensional body angle signal, and the three-dimensional body angular velocity signal are detected in real time by the acceleration sensor (6) and the gyroscope sensor (7). The XYZ three-dimensional acceleration signal, the three-dimensional body angle signal, and the three-dimensional body angular velocity signal are verified with the initial signal. By combining the ride comfort function module, the roll function module, and the pitch function module, the road information and the driver's operating intention can be identified. The suspension controller (5) issues adjustment commands to the solenoid valve, and the airbag actively adjusts the ride comfort, body roll and body pitch. Active ride comfort control: Road surface speed power spectral density: Road surface roughness power spectral density: ; in: For reference spatial frequency, ; This is the Z-axis acceleration signal. For the variance of the acceleration signal, For the vehicle body acceleration spectrum characteristics, For vehicle speed signal; The road surface grade can be identified based on the power spectral density of road surface roughness. Based on the vehicle speed, the appropriate stiffness of the airbag is analyzed using calibration methods, and the suspension controller issues adjustment commands to the solenoid valve.

2. The control method of the air suspension closed-loop control system as described in claim 1, characterized in that: Active body roll control: Vehicle turning radius: Wheel turning angle: ; in: This is the yaw rate signal. This refers to the car's wheelbase. The suspension controller adjusts according to the wheel angle of the vehicle body. The roll angle signal is analyzed to interpret driving behavior. If the roll angle signal is consistent with the wheel turning angle, there is a steering action. The suspension controller analyzes the airbag stiffness according to the lateral acceleration signal and the calibration method, compensates the suspension support force, and controls the body roll.

3. The control method of the air suspension closed-loop control system as described in claim 1, characterized in that: Active vehicle pitch control: Pitch angle difference: Front axle load increment: ; in: For pitch angle signal, This is the root mean square of the pitch angle over a period of time under constant velocity in the initial stage. For the total mass of the vehicle, It is a longitudinal acceleration signal. This refers to the wheelbase of the entire vehicle. The height of the center of mass; The suspension controller analyzes driving behavior based on vehicle pitch angle and longitudinal acceleration signals. If the longitudinal acceleration is in the same direction as the pitch angle and the acceleration exceeds a certain threshold, the airbag pressure adjustment is activated.

4. The control method of the air suspension closed-loop control system as described in claim 3, characterized in that: The suspension controller uses the pitch angle difference. Front axle load increment: By combining calibration methods to analyze the required compensation air pressure for the airbag, the airbag pressure is adjusted through a solenoid valve.

5. The control method of the air suspension closed-loop control system as described in claim 1, characterized in that: It also includes priority verification of the three adjustment signals of the ride comfort module, roll function module, and pitch function module; when all three function modules issue adjustment signals, the priority of the verification signals is determined, with roll signal priority > pitch signal priority > ride comfort signal priority; when a certain signal is missing or a certain signal remains unchanged, the verification is not performed by reference signal. When a functional module detects a missing signal during signal verification, a corresponding functional warning message will pop up based on the scope of the signal's impact.

6. The control method of the air suspension closed-loop control system as described in claim 1, characterized in that: The air suspension closed-loop control system mainly includes a gyroscope sensor (7), an acceleration sensor (6), a CAN bus, a suspension controller (5), a solenoid valve, and an airbag. The acceleration sensor (6) and the gyroscope sensor (7) are located at the center of gravity of the vehicle. The gyroscope sensor (7) and the acceleration sensor (6) are connected to the suspension controller (5) via the CAN bus, the solenoid valve, and the airbag.

7. The control method of the air suspension closed-loop control system as described in claim 6, characterized in that: Also includes: Ride comfort module: Based on the acceleration signal from the accelerometer, suspension performance parameters, vehicle speed signal, and in conjunction with the suspension controller, the airbag pressure corresponding to the ride comfort is analyzed. Roll function module: Based on the vehicle yaw rate and speed signals from the gyroscope sensor, the wheel angle, roll angle, and lateral acceleration signals from the suspension controller, and in conjunction with the suspension controller, the airbag pressure corresponding to the roll compensation is analyzed. Pitch function module: Based on the constant speed pitch angle signal of the suspension controller, road surface tilt angle, driver driving behavior, pitch angle difference, longitudinal acceleration, and in conjunction with the suspension controller, the airbag pressure corresponding to the pitch compensation is analyzed.

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