Air suspension function level simulation and fault injection test system

Abstract

The invention relates to the technical field of suspension testing, and discloses an air suspension function level simulation and fault injection testing system which comprises an upper computer, a real-time simulation platform, a load board card set and an air suspension controller. The real-time simulation platform is internally provided with a whole vehicle model and a double-cavity air spring and adjustable damping shock absorber function level model, and suspension physical state calculation, valve state judgment and model parameter updating are achieved. The load board card group is an electrical interface, a valve system load board card of the load board card group equivalently simulates a real vehicle electromagnetic valve load through an impedance-matched inductance resistance load network, and the load board card group can also collect a controller driving current and transmit the controller driving current back to the simulation platform; the simulation platform judges the valve state according to the actually measured current, updates suspension function level model parameters, calculates mechanical response and feeds back the mechanical response to the whole vehicle model, and the controller receives signals of the simulation sensor and outputs driving current; the technical problems of high hardware cost investment and difficulty in quantitative analysis of a response mechanism in the prior art are solved.

Description

Technical Field

[0001] This invention relates to the field of suspension testing technology, and more specifically to an air suspension functional-level simulation and fault injection testing system. Background Technology

[0002] As a core component of intelligent vehicle chassis, the air suspension system consists of air springs, air supply units, sensor components, and a suspension controller (ECU). It adjusts vehicle height, maintains stability, and matches suspension stiffness according to the vehicle's operating conditions. The rationality of its control strategy directly affects vehicle comfort, handling performance, and dynamic safety. With the increasing intelligence of vehicles, the air suspension control logic is becoming increasingly complex, making functional verification under different operating conditions and abnormal conditions a core aspect of research and development.

[0003] However, existing air suspension verification methods have the following drawbacks: Existing air suspension tests mostly use physical test benches, which require building complex test environments containing a large number of dynamic components and aerodynamic parts. This results in large hardware investments, long test preparation cycles, and difficulty in quickly reusing the test environment. At the same time, due to limitations such as environment and road conditions, the repeatability and controllability of test results from physical test benches are poor, and they cannot simulate extreme failure scenarios, posing safety risks.

[0004] Existing air suspension simulation testing technologies often pursue high-precision multiphysics simulation, which results in high costs for modeling, parameter calibration, and real-time calculation. They also focus only on verification under normal operating conditions and have limited ability to simulate actual faults such as valve jamming, leakage, and signal bias. Furthermore, the high coupling between the signal simulation unit and the simulation model makes it impossible to construct a closed-loop control environment, and the controller's response mechanism to different signal sources, load conditions, and fault types is difficult to quantify and analyze. Summary of the Invention

[0005] The present invention aims to provide a functional-level simulation and fault injection testing system for air suspension to solve the technical problems of high hardware costs and difficulty in quantifying and analyzing response mechanisms in existing technologies.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: an air suspension functional-level simulation and fault injection testing system, comprising: The host computer is used to configure test conditions, set fault injection strategies, and sampling parameters. The real-time simulation platform has a built-in vehicle model and an air suspension functional level model. The air suspension functional level model includes a dual-chamber air spring functional level model and an adjustable damping shock absorber functional level model. The real-time simulation platform is used to realize the physical state calculation of the air suspension, real-time valve state determination, and dynamic updating of model parameters. The load board group serves as the electrical interface connecting the real-time simulation platform and the air suspension controller, and includes a valve system load board, a PSI5 height signal board, an analog voltage board, and a resistance analog board. Each independent channel of the valve system load board integrates a load network composed of inductors and resistors. The electrical parameters of the load network are calibrated to match the impedance characteristics of the actual vehicle solenoid valve coil, and are used to equivalently simulate the load of the actual vehicle solenoid valve. A current acquisition node is set on each equivalent load branch to collect the drive current output by the air suspension controller in real time and convert it into a digital quantity, which is then transmitted back to the real-time simulation platform via the communication bus. The air suspension controller, which is the controller under test, is used to receive the sensor signals simulated by the load board group, generate valve system drive commands according to the built-in control logic, and output drive current to the valve system load board. The real-time simulation platform determines the valve state based on the measured current value returned by the valve system load board, and updates the air circuit connection relationship and damping force parameters of the air suspension functional level model based on the determined valve state, recalculates the suspension mechanical response and feeds it back to the vehicle model.

[0007] The principle and advantages of this solution are as follows: In practical applications, the host computer first configures the test conditions, fault injection strategy, and sampling parameters according to the test requirements and sends them to the real-time simulation platform. The real-time simulation platform calculates the physical state parameters of the suspension corner points through the built-in vehicle model and transmits them to the air suspension functional level model. At the same time, the drive load board converts parameters such as suspension height, air pressure, and temperature into analog sensor signals that the air suspension controller can recognize and inputs them. The air suspension controller generates valve system drive commands according to its built-in control logic, and the output drive current is input to the valve system load board. The valve system load board simulates the real electrical circuit through an RL load network that matches the impedance of the solenoid valve coil of the actual vehicle. The solenoid valve is an electrical load, eliminating the need to build a physical test bench containing dynamic components and pneumatic parts. Simultaneously, the drive current is collected in real time through a current acquisition node, converted from analog to digital, and then transmitted back to the real-time simulation platform via a communication bus. The real-time simulation platform uses this measured current value as the sole criterion to accurately determine the working state of each valve. Based on the determination results, it updates the air circuit connectivity and damping force parameters of the air suspension functional level model, recalculates the suspension mechanical response, and feeds it back to the vehicle model, completing the dynamic closed loop of the vehicle-suspension system. In addition, combined with the fault injection strategy set by the host computer, it can achieve accurate injection of electrical and physical faults. The host computer synchronously collects the test data of the entire process and completes quantitative analysis.

[0008] By replacing physical components such as real solenoid valves with equivalent load circuits, the hardware configuration cost is significantly reduced. There is no need to build complex aerodynamic and dynamic components. The test environment can be quickly configured and reused through software, which solves the problems of large investment in existing physical test bench hardware, long test preparation cycle and poor environment reusability. By using fully software-defined test conditions and fault injection strategies, the testing process can be accurately controlled, the test results can be reproduced, and various extreme fault scenarios can be simulated in a safe laboratory environment, eliminating the safety risks of real vehicle testing and solving the problems of poor repeatability and controllability of physical bench test results and the inability to simulate extreme fault scenarios. Replacing high-precision multiphysics simulation with functional-level simulation models significantly reduces the cost of modeling, parameter calibration, and real-time calculation, improves the practicality of simulation testing, and solves the problem of high cost of high-precision modeling in existing simulation testing. By combining electrical fault injection of valve system load cards with physical fault injection of real-time simulation platforms, accurate simulation of various types of actual faults such as valve body jamming, leakage, and signal bias can be achieved, covering the testing needs of normal and abnormal full-condition operation, and solving the problem that existing simulation tests only focus on normal operating conditions and have limited fault simulation capabilities. By constructing a full-link dynamic closed loop of "sensor signal simulation - ECU drive output - measured current feedback - model parameter update - suspension status feedback", a control closed-loop environment consistent with the real vehicle is built, which solves the problem that the existing simulation test signal simulation unit has a high degree of coupling with the simulation model and cannot build a closed-loop control environment. By using measured current to drive closed-loop model updates and synchronously collecting time-stamped test data throughout the entire process, a systematic, precise, and quantitative analysis of ECU control strategies, fault diagnosis, and fault-tolerant response mechanisms is achieved. This provides reliable data support for the research and optimization of air suspension ECUs and solves the problem of difficulty in quantitatively analyzing the controller's response mechanisms to different signal sources, load conditions, and fault types.

[0009] Preferably, as an improvement, the multi-channel structure of the valve system load board covers all actuator drive circuits of the air suspension, including the air pump relay, air tank valve, exhaust valve, and height valve, stiffness valve, and continuous damping control solenoid valve at the four suspension corner points; the equivalent load circuit of each channel uses a resistor and an inductor connected in series to form an equivalent load, and a sampling resistor is connected in series at the front end of the main circuit, and the circuit current is calculated by collecting the voltage drop across the sampling resistor.

[0010] The benefits of this improvement are as follows: the multi-channel structure achieves full coverage of the entire actuator drive circuit of the air suspension, and the entire system test can be completed without the need for additional hardware, thus improving the integrity and efficiency of the test; the use of an equivalent load with a resistor and an inductor in series can accurately match the impedance characteristics of different actuator solenoid valves; the design of a sampling resistor in series at the front end of the main circuit allows all the ECU drive current to flow through the sampling resistor, and the circuit current calculated by voltage drop is more accurate, providing reliable measured data support for subsequent valve state determination and model updates; at the same time, the integrated design of the equivalent load and the sampling circuit makes the single-channel structure more compact and reduces the complexity of the board hardware design.

[0011] Preferably, as an improvement, the valve system load card integrates a controllable short-circuit branch on a specific channel. According to the software instructions of the host computer or real-time simulation platform, it actively triggers the injection of electrical faults to short-circuit the power supply or to ground at a specified time to verify the fault diagnosis and fault-tolerant control capabilities of the air suspension controller.

[0012] The benefits of this improvement are as follows: precise injection of electrical faults at specified times and channels can be achieved through software commands without modifying the hardware structure, making the operation flexible and the fault scenarios reproducible; it can simulate the most common power supply / ground short circuit faults in real vehicles, filling the gap in existing testing technologies that are difficult to verify the electrical fault diagnosis and fault-tolerant control capabilities of ECUs in a controlled environment; the fault injection is linked with the measured current acquisition and model closed-loop update, which can synchronously collect the changes in drive current after the ECU fault response, realize the quantitative analysis of the ECU fault handling capability, and improve the depth and practicality of the test.

[0013] Preferably, as an improvement, the dual-chamber air spring functional level model replicates the air circuit topology of a real vehicle dual-chamber air spring, including an air supply assembly and four corner dual-chamber air springs; the air supply assembly includes an air pump, an exhaust valve, an air tank, and an air tank valve; each air spring corresponds to a height valve that controls the inflation and deflation of air and a stiffness valve that controls the opening and closing of the main and auxiliary chambers; the working state of all valves is determined by the real-time simulation platform based on the measured current collected by the valve system load board and drives the synchronous switching of the air circuit state in the model.

[0014] The beneficial effects of this improvement are: it accurately replicates the complete air circuit topology of the real vehicle's dual-chamber air spring, ensuring that the air circuit logic of the functional-level simulation is highly consistent with that of the real vehicle, thus guaranteeing the authenticity of the simulation results for suspension height and stiffness adjustment; it uses the measured current as the sole criterion for determining the valve's working state, driving the synchronous switching of the model's air circuit state, realizing real-time linkage between the ECU control output and the model's state, constructing an air circuit control closed loop consistent with the real vehicle, avoiding simulation deviations caused by preset valve states, and improving the accuracy of simulation testing.

[0015] Preferably, as an improvement, the adjustable damping shock absorber functional level model is configured with independent shock absorber simulation models at the four suspension corners of the vehicle. Each model is a lookup table mapping module containing the relationship between current, shock absorber compression speed and damping force. The real-time simulation platform inputs the measured drive current of the continuous damping control solenoid valve collected by the valve system load board and the real-time compression speed of the shock absorber output by the vehicle model into the lookup table module to calculate the current damping force and feed it back to the vehicle model.

[0016] The beneficial effects of this improvement are as follows: the independent simulation model at each of the four corner points enables personalized calculation of damping force, accurately replicating the independent adjustment logic of the shock absorbers at each corner of the vehicle; the lookup table mapping module replaces the complex high-precision fluid dynamics simulation, significantly reducing the real-time computation cost of the model and improving simulation efficiency, while the pre-calibrated current-velocity-damping force relationship ensures the accuracy of the calculation; the damping force is calculated using the measured drive current and real-time compression speed as dual inputs, realizing dynamic closed-loop simulation of damping adjustment, accurately replicating the continuously variable physical process of damping in the vehicle, and providing a reliable basis for the verification of ECU damping control strategy.

[0017] Preferably, as an improvement, the system supports physical fault injection by modifying model parameters through the real-time simulation platform. Fault types include gas leakage, sensor drift / bias, valve jamming, and communication abnormalities. Among them, the air leakage fault is achieved by modifying the air pressure attenuation parameter of the air spring cavity, the sensor drift / bias fault is achieved by modifying the simulated signal parameters of altitude, air pressure, and temperature, the valve body jamming fault is achieved by fixing the valve opening and closing state in the model, and the communication abnormality fault is achieved by interrupting signal transmission.

[0018] The benefits of this improvement are as follows: hardware-free injection of various types of physical faults can be achieved by modifying model parameters, eliminating the need to build complex physical fault environments and significantly reducing the cost and preparation cycle of fault testing; it covers common physical faults in air suspension vehicles, such as air circuits, sensors, valve bodies, and communication, achieving comprehensive coverage of fault scenarios and improving the integrity of testing; it allows for gradient fault injection of mild, moderate, and severe faults by adjusting parameter ranges, accurately verifying the ECU's response and processing capabilities under different fault levels, while the fault injection process is fully controllable and the test results are repeatable, facilitating the optimization and iteration of ECU fault diagnosis strategies.

[0019] Preferably, as an improvement, the PSI5 height signal board receives the air spring height values ​​at each corner point calculated and output by the real-time simulation platform based on the vehicle model, generates a height simulation signal consistent with the actual vehicle height sensor protocol, and sends it to the air suspension controller; the analog voltage board receives the air spring pressure simulation voltage signal converted by the real-time simulation platform and outputs it to the air suspension controller; the resistance simulation board simulates the signal characteristics of the actual vehicle temperature sensor through resistance value changes and is connected to the temperature sensor interface of the air suspension controller.

[0020] The beneficial effects of this improvement are as follows: Each signal board simulates the actual vehicle's height, air pressure, and temperature sensor signals, with the height signal consistent with the actual vehicle's PSI5 protocol, and the air pressure and temperature signals matching the signal characteristics of the actual vehicle's sensors. This ensures that the simulated sensor signals received by the ECU are completely consistent with the actual vehicle's operating conditions, guaranteeing the authenticity of the ECU's control logic output. Each signal board, as an independent module, completes the simulation and transmission of different types of signals, avoiding mutual interference between signals and improving the accuracy and stability of signal simulation. The signal boards are linked with the real-time simulation platform, which can dynamically adjust the simulated signals according to the model's calculation results, realizing real-time dynamic simulation of sensor signals and providing reliable ECU input signal support for building a complete test closed loop.

[0021] Preferably, as an improvement, the real-time simulation platform determines the valve state based on a preset current threshold or a specific current value: when the current value is zero, the valve is determined to be closed; when the current value is greater than the preset threshold, the valve is determined to be open. The continuously damped control solenoid valve determines the continuous adjustment state based on the specific current value.

[0022] The benefits of this improvement are as follows: Different valve state determination logic is designed for on / off valves and continuously regulating CDC valves, matching the control characteristics of different types of solenoid valves in real vehicles, making the valve state determination results more consistent with the actual working state of the vehicle; the threshold determination logic for on / off valves is simple and efficient, and can quickly and accurately identify the valve opening and closing state; the specific current value determination logic for CDC valves can achieve accurate identification of the continuously regulating state of damping, providing a reliable basis for the dynamic calculation of damping force; the preset current threshold can be flexibly adjusted according to the characteristics of different solenoid valves, improving the system's adaptability to different models of air suspension ECUs.

[0023] Preferably, as an improvement, after the single-channel input air suspension controller drive current of the valve system load board flows through the series 2000Ω sampling resistor and the load network, the current acquisition node is connected in parallel across the sampling resistor. The acquired voltage signal is amplified, filtered, and converted from analog to digital to form measured current data, which is output to the 485 differential communication bus and uploaded to the real-time simulation platform. This measured current data serves as the sole basis for the real-time simulation platform to determine the corresponding valve opening / closing status or working position. At the same time, an indicator light is connected in parallel across the load network to output a status indication signal based on the current on / off state. The inductance of the load network includes 23mH and 12mH, and the resistive elements of the load network include 7Ω, 16Ω and 4Ω.

[0024] The benefits of this improvement are as follows: the fixed value design of the 2000Ω sampling resistor simplifies current calculation; the amplification, filtering, and analog-to-digital conversion processes effectively improve the accuracy of the measured current data; the 485 differential communication bus ensures the anti-interference and real-time performance of data transmission; and the use of measured current data as the sole basis for valve status determination completely avoids judgment deviations caused by non-measured signals; the indicator light design enables visualization of the channel's working status, facilitating quick troubleshooting of hardware connections and channel faults by testers, thus improving debugging efficiency during the testing process; the load network configuration with multiple specifications of inductance and resistance parameters can accurately match the impedance characteristics of different types of solenoid valves in air suspension systems, allowing for adaptation to different actuators without changing the board, significantly improving the versatility and adaptability of the valve system load board. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall system structure according to an embodiment of the present invention.

[0026] Figure 2 This is a schematic diagram of the connection relationship in the functional level model of a double-cavity air spring.

[0027] Figure 3 This is a schematic diagram of the connection relationships in the functional level model of the vibration damper.

[0028] Figure 4 This is a schematic diagram of the valve system load board structure. Detailed Implementation

[0029] The following detailed description illustrates the specific implementation method: Example The basics are as follows: Figure 1 As shown, the air suspension functional-level simulation and fault injection test system includes: a host computer, a real-time simulation platform, a load board group, and an air suspension controller ECU. Each module achieves bidirectional interconnection through standardized communication interfaces and electrical wiring harnesses, forming a dynamic closed loop of the entire process of "command issuance - signal simulation - control output - data acquisition - model update - analysis and optimization".

[0030] The real-time simulation platform includes a built-in vehicle model and an air suspension functional level model. The air suspension functional level model further includes a dual-chamber air spring functional level model and an adjustable damping shock absorber (CDC) functional level model. The load board group serves as the core electrical interface, including a valve system load board, a PSI5 height signal board, an analog voltage board, and a resistance analog board.

[0031] Specifically, The host computer is used to configure test conditions, set fault injection strategies, and sample parameters. It connects to the real-time simulation platform via a communication interface. Test conditions configured on the host computer include vehicle speed, longitudinal acceleration, braking, and steering. Fault injection strategies set on the host computer include fault type, triggering timing, and fault magnitude.

[0032] The host computer is also responsible for the real-time storage, visualization, and quantitative analysis of all system test data, enabling timestamp-based traceability of test data and multi-dimensional parameter correlation analysis. The host computer performs data acquisition and real-time storage by configuring parameters such as sampling frequency and storage path.

[0033] The host computer receives data such as model running status, valve status judgment results, and fault trigger status from the real-time simulation platform in real time. It can dynamically adjust the operating conditions and fault strategies according to the test requirements, so as to achieve flexible and controllable test process.

[0034] The host computer can complete the configuration and management of the entire testing process without manual intervention in hardware debugging, which greatly shortens the test preparation cycle and improves test efficiency. The full-dimensional data storage and analysis provides accurate data support for ECU control strategy optimization and fault diagnosis system design.

[0035] Real-time simulation platform: It has a built-in whole vehicle model and air suspension functional level model, which realizes the physical state calculation of air suspension, real-time valve state determination, dynamic update of model parameters, and completes the instruction / data interaction with the host computer and load board group.

[0036] The whole vehicle model is a basic model of vehicle dynamics, covering dynamic simulation of all working conditions such as vehicle driving, steering, braking, acceleration and deceleration.

[0037] Based on the test conditions issued by the host computer, the vehicle model calculates the overall vehicle motion state and the physical input parameters of the four suspension corner points, and then inputs these physical parameters into the air suspension functional level model in real time. The overall vehicle motion state includes vehicle speed, longitudinal / lateral acceleration, vehicle attitude, and wheel speed. The physical input parameters of the four suspension corner points include spring compression, shock absorber compression / extension speed, and relative displacement between the wheels and the vehicle body. The whole vehicle model provides dynamic and real-time input for the air suspension functional model, accurately reproducing the actual working requirements of the air suspension under different driving conditions, so that the simulation test is highly consistent with the actual vehicle conditions.

[0038] The air suspension functional level model takes the suspension corner point physical parameters output from the whole vehicle model as input, and calculates the support force of the air springs and the damping force of the adjustable shock absorbers at each corner point. The mechanical calculation results are fed back to the whole vehicle model in real time to complete the dynamic closed loop of the whole vehicle-suspension.

[0039] The whole vehicle model and the air suspension functional level model form a real-time dynamic closed loop of "input-solution-feedback-resolution", which accurately replicates the interaction relationship in the real vehicle where "the vehicle driving state determines the suspension adjustment requirements and the suspension mechanical response affects the vehicle driving state", making the dynamic characteristics of the hardware-in-the-loop test highly consistent with the real vehicle.

[0040] The air suspension functional level model unit includes a dual-chamber air spring functional level model and an adjustable damper functional level model. The dual-chamber air spring functional level model and the adjustable damper functional level model work together to realize the core functions of air suspension height adjustment, stiffness adjustment, and damping adjustment. All adjustment actions are based on the measured drive current of the ECU collected by the valve system load board, ensuring complete consistency with the actual vehicle control logic.

[0041] As attached Figure 2 As shown, the functional level model of the dual-chamber air spring is used to replicate the air circuit topology of the real vehicle's dual-chamber air spring, including the air supply assembly and four corner dual-chamber air springs. The air supply assembly specifically includes an air pump, an exhaust valve, an air tank, and an air tank valve. The four corner dual-chamber air springs are specifically the left front, right front, left rear, and right rear. Each air spring corresponds to a height valve that controls the inflation and deflation of the air and a stiffness valve that controls the on / off state of the main and auxiliary chambers. The operating state of all valves is determined by the real-time simulation platform based on the measured current.

[0042] The air pump outlet is connected to the air tank and the height valves at each corner point via a one-way valve. The exhaust valve controls the connection between the exhaust main pipe and the atmosphere. The height valve is a two-way solenoid valve, with one end connected to the distribution valve and the other end connected to the main chamber of the air spring. Specifically, the distribution valve is an air passage junction / distribution structure that connects the air pump outlet to the air tank and the height valves at each corner point after passing through the one-way valve. The stiffness valve connects the main chamber and the auxiliary chamber of the air spring at the same corner point. All valves are closed during system initialization, and the air tank is pre-stored with compressed gas.

[0043] As attached Figure 2As shown, the left side contains the air source and air supply assembly module, the right side contains the four suspension corner point actuator modules, the upper side contains the sensor signal input harness, and the lower side contains the solenoid valve drive harness. The upper sensor signal input harness transmits the height data of the four suspension corner points to the ECU in real time for height control and fault diagnosis. The lower solenoid valve drive harness is controlled by the ECU through output drive current to control the on / off state of each solenoid valve, realizing height adjustment, stiffness adjustment, and exhaust pressure relief.

[0044] When the host computer issues a lifting command, the ECU drives the air tank valve and the target corner height valve to open. The real-time simulation platform opens the corresponding valves in the model according to the measured current. Compressed air flows along "air tank → height valve → air spring cavity". The cavity pressure increases and the support force increases, driving the vehicle body in the whole vehicle model to move upward relative to the axle. When a lowering command is issued, the ECU drives the corresponding height valve and exhaust valve to open. The air path in the model switches to "air spring cavity → height valve → exhaust valve → atmosphere". The cavity depressurizes and the support force decreases, causing the vehicle body to sink.

[0045] When the stiffness valve is on, the main and auxiliary chambers are connected, the effective air chamber volume increases, the system's equivalent stiffness decreases, and vehicle comfort is improved; when the stiffness valve is off, the two chambers are isolated, the effective air chamber volume decreases, the equivalent stiffness increases, and vehicle handling stability is improved.

[0046] Throughout the process, the drive current of all valve coils is acquired and measured with high precision by the valve system load board and transmitted back to the simulation platform in real time. This is not only used to synchronously switch the air circuit state of the drive function level model, but also constitutes a complete hardware-in-the-loop closed loop of "ECU control output → load current acquisition → model air circuit update → suspension mechanical response → ECU sensor input".

[0047] The dual-chamber air spring functional level model eliminates the need for real air springs, air supply units, and other pneumatic components. Through functional level simulation, it accurately reproduces the height and stiffness adjustment logic of the air suspension. Moreover, the adjustment action is driven by the measured current of the ECU, which is completely synchronized with the working state of the real vehicle, and the test results are real and reliable.

[0048] As attached Figure 3 As shown, the adjustable damping shock absorber (CDC) functional level model is used to configure independent shock absorber simulation models for the four suspension corners of the vehicle. The four corners of the vehicle are the front left, front right, rear left, and rear right. The drive ports of the continuous damping control solenoid valves (CDC valves) on the ECU are connected to the channels on the valve system load board through wiring harnesses, namely the front left CDC valve, the front right CDC valve, the rear left CDC valve, and the rear right CDC valve.

[0049] Appendix Figure 3 In the middle, the upper wiring harness is the vehicle sensor input interface, the middle area is the CDC functional level model of the four suspension corner points, and the lower wiring harness is the valve system load board drive interface.

[0050] The downward signal from the upper wiring harness arrow comes from the vehicle model. It enters the CDC functional level model at the corresponding corner point through this wiring harness and is also simultaneously input to the air suspension ECU. This provides dynamic physical input to the CDC functional level model, determining the basic damping requirements under the current operating conditions. For example, greater damping is needed to suppress body roll when cornering at high speed. It also provides state perception input to the air suspension ECU, which calculates the target damping force and outputs the corresponding CDC valve drive current.

[0051] The upward signal from the upper wiring harness arrow originates from the CDC functional level model and the air suspension ECU. Specifically, it represents the real-time damping force and damping adjustment status calculated by the CDC functional level model, as well as the CDC valve control commands, fault diagnosis status, and system operating mode from the air suspension ECU. The signal travels from bottom to top and is transmitted back to the vehicle dynamics model.

[0052] Appendix Figure 3 In the model, the four suspension corner points of the CDC functional level repeat four identical sets of model units. Each set of models is a lookup table mapping module for "current-damper compression velocity-damping force". The model has a built-in pre-calibrated multi-dimensional lookup table relationship. Based on the two input parameters of current and velocity, it quickly calculates the damping force output by the current shock absorber. The multiple curves in the figure represent the "velocity-damping force" characteristic curves under different currents. The calculated damping force is fed back to the vehicle dynamics model, affecting the vertical, pitch, and roll movements of the vehicle body, thereby achieving damping adjustment to suppress the vehicle's attitude.

[0053] The signal from the lower wiring harness comes from the CDC valve drive current output by the air suspension ECU. After being acquired by the valve system load board, it is input upwards to the CDC model at the corresponding corner point through the red wiring harness. The actual control output current of the ECU is transmitted to the CDC model as the control input for damping adjustment.

[0054] The real-time compression speed of the shock absorber output from the vehicle model is used as the dynamic physical input, and the measured drive current of the CDC valve collected by the valve system load board is used as the damping adjustment input. The damping force is calculated in real time based on the pre-calibrated lookup table mapping relationship of "current-shock absorber compression speed-damping force". The calculation results are fed back to the vehicle model, affecting the vehicle body dynamics response.

[0055] The adjustable damping shock absorber functional level model continuously reads the measured current of each CDC channel through a real-time simulation platform. The current value and the real-time suspension compression speed are input into the lookup table module to calculate the current precise damping force. The ECU can drive the lookup table module to dynamically calculate the damping force by adjusting the CDC valve drive current, thus replicating the physical process in the real vehicle of "adjusting the CDC valve current to change the throttling area and achieve continuously variable damping".

[0056] The adjustable damping shock absorber functional level model accurately simulates the suppression effect of different damping strategies on the vertical, pitch, and roll motion of the vehicle body. It can fully verify the rationality of the ECU damping adjustment control strategy, and the lookup table solution method greatly reduces the model's computational cost and improves real-time performance.

[0057] Load cell board assembly: This is a dedicated electrical interface bridge connecting the real-time simulation platform and the air suspension ECU. It is a key hardware component used to replicate the electrical characteristics of the real vehicle, perform fault injection, and acquire current. Each board has a clear division of labor and works collaboratively to convert the digital signals of the simulation model into electrical signals that the ECU can recognize, and at the same time, convert the electrical output of the ECU into digital data that the simulation model can use, thus realizing an electrical closed loop between simulation and hardware. The load board group specifically includes a valve system load board, a PSI5 height signal board, an analog voltage board, and a resistor analog board.

[0058] As attached Figure 4 As shown, the valve system load board is a multi-channel, high-precision load simulation and signal acquisition unit. All air suspension actuator drive circuits are connected to the valve system load board via wiring harnesses, possessing core functions such as equivalent load simulation, high-precision current acquisition feedback, and active electrical fault injection. The air suspension actuator drive circuits connected to the valve system load board specifically include: air pump relay, air tank valve, exhaust valve, and height valve, stiffness valve, and CDC valve at the four corner points.

[0059] Each independent channel of the valve system load board integrates a load network composed of precision inductors and resistors. Its electrical parameters, such as inductance and resistance, are rigorously calibrated to perfectly match the impedance characteristics of the actual vehicle's solenoid valve coil, ensuring that the load sensed by the ECU drive circuit is consistent with the actual vehicle operating conditions. This eliminates the need for actual solenoid valve hardware, significantly reducing hardware investment costs. Furthermore, by adjusting circuit parameters through software, it can quickly adapt to different ECU models, improving system compatibility.

[0060] A high-precision current acquisition node is set on each equivalent load branch of the valve system load board. The current signals of all channels are converted into digital quantities after sampling resistors, amplification, filtering, and analog-to-digital conversion. The digital signals are then uploaded to the real-time simulation platform in real time via a 485 differential communication bus. The platform accurately determines the real-time operating status of each valve based on preset thresholds or specific current values. If the current is zero at the preset threshold, the valve is considered closed; if the current is greater than the threshold, the valve is considered open. The specific current value is used for continuous adjustment of the CDC valve.

[0061] High refresh rate and high precision current acquisition provide real and real-time ECU output data for valve state determination and model update, avoiding the errors of traditional preset current drive and ensuring that model update is synchronized with the actual output of ECU.

[0062] As attached Figure 4In the center, the left-hand area contains multiple independent solenoid valve loads, covering all actuators of the air suspension. In the equivalent load circuit of each channel, a resistor (7Ω / 16Ω / 4Ω) and an inductor (23mH / 12mH) are connected in series to form the RL equivalent load of the actual vehicle's solenoid valve coil. A 2000Ω sampling resistor is connected in series at the very beginning of the entire main circuit, and a data acquisition node is set in parallel across the 2000Ω sampling resistor to measure the voltage drop across it, thereby calculating the current. An indicator light is connected in parallel across the RL equivalent load to visually indicate the channel's on / off status.

[0063] The current flows out from the ECU's 12V positive terminal, first through a 2000Ω sampling resistor, and then splits into two paths. One path passes through an indicator light, and the other path passes through a series network of resistors and inductors, i.e., the main load branch. Finally, the current converges and flows back to the ECU's drive negative terminal.

[0064] The area on the right is the current acquisition board, which is labeled with the current acquisition channels corresponding to each solenoid valve. The acquired current data is uploaded to the real-time simulation platform through the 485+ / 485- differential communication interface. The upper left corner is the ECU power supply, which is used to provide 12V / 24V power to the board and ECU.

[0065] The valve system load card integrates controllable short-circuit branches on specific channels. Through software commands from a host computer or real-time simulation platform, typical wiring harness faults such as "short circuit to power supply" or "short circuit to ground" can be actively triggered on a designated channel at any time. This enables comprehensive testing of air suspension electrical faults in a safe and controlled laboratory environment, verifying the ECU's fault diagnosis and fault tolerance capabilities, and solving the pain point of traditional testing's inability to simulate electrical faults.

[0066] The PSI5 height signal board receives the air spring height values ​​at each corner point calculated by the real-time simulation platform based on the vehicle model. It generates a height simulation signal consistent with the protocol of the actual vehicle height sensor and sends this signal to the ECU, achieving accurate simulation of the actual vehicle height sensor signal. The PSI5 height signal board ensures complete matching of the signal protocol with the actual vehicle, guaranteeing that the ECU's recognition of the height signal is consistent with the actual vehicle, providing a realistic signal input for verifying the ECU's height adjustment control strategy.

[0067] The analog voltage board receives the simulated air spring pressure voltage signal converted by the real-time simulation platform, converts it into a voltage-type simulated air pressure signal recognizable by the ECU, and outputs it to the ECU to simulate the actual vehicle air pressure sensor signal. This accurately reproduces the sensor signal characteristics under different air pressure conditions and can simulate abnormal states such as air pressure signal drift and bias, providing support for the verification of ECU air pressure feedback control strategies.

[0068] The resistance simulation board allows for setting appropriate resistance values ​​based on test requirements. By varying the resistance value, it simulates the signal characteristics of a real vehicle's temperature sensor. Connecting to the ECU's temperature sensor interface, it simulates temperature signals. This enables flexible adjustment of the resistance value to simulate sensor signals under different ambient temperatures. It can also simulate abnormal temperature signals, improving the test coverage of temperature-related control strategies and fault diagnosis.

[0069] Air suspension controller ECU: This is the system test object and the actual air suspension controller of the vehicle, with built-in original factory control logic. Its core functions include: receiving sensor signals such as height, air pressure, and temperature simulated by the load board group, generating valve system control commands for each actuator according to the built-in control logic, and outputting them to the corresponding channels of the valve system load board in the form of drive current to execute the adjustment strategies of vehicle height, suspension stiffness, and damping. It also has fault diagnosis and fault-tolerant control capabilities.

[0070] The overall workflow of the system includes: Step 1: Initialization Configuration of Operating Conditions: The host computer sends specific test operating condition parameters to the real-time simulation platform according to the test requirements, such as vehicle speed of 60km / h, emergency left turn, and braking deceleration. Meanwhile, basic parameters such as sampling frequency and data storage path are configured. Step 2: Initial calculation of vehicle and suspension status: After receiving the operating parameters, the real-time simulation platform calculates the core physical state of the four suspension corners of the vehicle through the vehicle dynamics model, including spring compression and shock absorber compression speed. This data is used as the input parameters of the air suspension functional level model. Step 3: Sensor Signal Simulation and ECU Input: The real-time simulation platform inputs the physical state of the suspension corner points into the air suspension functional level model, calculates key parameters such as target height, air spring pressure, and temperature at each corner point, and distributes them to the corresponding load boards according to signal type: the PSI5 height signal board generates a height simulation signal consistent with the real vehicle protocol, the simulation voltage board converts the air pressure value into a voltage-type simulation signal, and the resistance simulation board simulates the temperature signal through the resistance value. All simulation signals are synchronously input to the air suspension ECU. Step 4: ECU control command output: After receiving the analog sensor signal, the ECU generates drive commands for each actuator according to the built-in control logic and outputs them in the form of current to the corresponding channel of the valve system load board. Step 5: Real-time acquisition of measured current and valve status determination: The valve system load board performs high-precision real-time acquisition of the drive current output by the ECU, converts the analog current signal into a digital quantity, and transmits it back to the real-time simulation platform through the 485 communication bus; the platform accurately determines the real-time working status of each valve based on the preset current threshold or the specific current value. Step Six: Suspension Model State Update and Closed-Loop Cycle: Based on the determined valve state, the real-time simulation platform updates the core parameters of the air suspension functional level model in real time, such as the air circuit connectivity, damping force parameters, and air pressure change law. It then recalculates the physical state of the suspension corner points and returns to Step Three to complete a new round of signal simulation and ECU input, forming a continuous dynamic closed loop.

[0071] This enables fully automated operation without human intervention, with each step synchronized in real time and negligible time delay, accurately replicating the dynamic control process of air suspension in a real vehicle, and significantly improving the authenticity and repeatability of test results.

[0072] This system constructs a multi-level nested data closed-loop mechanism, including command closed loop, signal / current closed loop, model / state closed loop, and data acquisition and analysis closed loop. It achieves full-dimensional acquisition, real-time synchronization, and correlation analysis of commands, signals, currents, model states, fault data, and ECU response data; ensuring the authenticity, integrity, and traceability of test data, providing solid support for the quantitative analysis of ECU control strategies and fault handling capabilities.

[0073] The multi-level nested data closed-loop mechanism is as follows: The first-level instruction closed loop, namely the host computer-real-time simulation platform: the host computer sends instructions such as operating condition configuration, fault injection, and sampling parameters to the real-time simulation platform, forming an instruction downlink; the real-time simulation platform uploads data such as model running status, valve state judgment results, fault trigger status, and test progress to the host computer in real time, forming a status uplink; the host computer can adjust the test strategy in real time according to the status returned by the platform, realizing a two-way closed loop between instructions and status, ensuring the controllability of the test process.

[0074] The two-level signal / current closed loop, namely the real-time simulation platform-load board group-ECU: The real-time simulation platform converts the suspension state parameters into analog sensor signals, which are input to the ECU through the load board group, forming an analog signal downlink; the ECU outputs valve system drive current to the valve system load board, forming an electrical command downlink; the valve system load board collects the measured current and sends it back to the real-time simulation platform, forming a measured current uplink; this closed loop is the core data link of the system, realizing seamless linkage of "analog sensor signal - ECU actual output - measured current feedback", ensuring that the simulation platform obtains the ECU's real control output data.

[0075] The three-level model / state closed loop consists of the vehicle dynamics model and the air suspension functional level model: the vehicle dynamics model calculates the physical state of the suspension corners and inputs it into the air suspension functional level model to form a state uplink; the air suspension functional level model updates parameters such as air circuit and damping force based on the valve state determined by the measured current, and calculates mechanical parameters such as suspension support force and damping force, which are fed back to the vehicle dynamics model; the vehicle dynamics model recalculates the vehicle driving state based on the suspension mechanical parameters to form a state uplink; this closed loop accurately reproduces the dynamic correlation between "vehicle driving state - suspension physical state - suspension mechanical response" in a real vehicle.

[0076] The four-level data acquisition and analysis closed loop, namely the whole system and the host computer: The host computer realizes multi-dimensional and highly synchronous data acquisition of the whole system through a real-time simulation platform. The acquired content includes operating parameters, suspension physical state parameters, ECU output parameters, valve state judgment results, model update parameters, fault trigger parameters, ECU fault response data, etc. All data are timestamped, and the acquisition frequency is consistent with the physical closed loop frequency of the system to ensure the time synchronization of data. The host computer stores and visualizes the acquired data in real time, and analyzes the rationality of the ECU's control strategy under normal operating conditions, the diagnostic accuracy and fault-tolerant control effectiveness under fault scenarios through a quantitative analysis model. At the same time, it can adjust the test conditions and fault strategies in real time according to the analysis results to realize the "test-analysis-optimization-retest" closed loop to ensure test coverage and verification depth.

[0077] This system supports full-dimensional, configurable, and reproducible fault injection for both electrical and physical faults. Fault type, triggering timing, and fault magnitude can all be flexibly set via a host computer. All faults are implemented in a controlled laboratory environment without hardware modification or ECU damage. After fault injection, the system maintains a complete data loop and can synchronously collect full-dimensional fault response data from the ECU, comprehensively verifying the ECU's fault diagnosis and fault-tolerant control capabilities. Electrical fault injection is achieved through a valve system load card. For electrical components such as air suspension solenoid valves and wiring harnesses, the most common short circuit to power supply and short circuit to ground faults in real vehicles are simulated. The fault can be triggered through the host computer software. Fault triggering and recovery can be controlled in real time without any hardware modification.

[0078] Physical faults are injected by modifying model parameters through a real-time simulation platform. This simulates various abnormal states commonly found in real vehicles for air suspension physical components, sensors, and air circuit systems, without the need to build any physical fault environment.

[0079] The core simulated fault types include: air circuit leakage, sensor drift / bias, valve body jamming, and communication anomalies, etc., and the fault amplitude can be precisely adjusted to achieve gradient testing of mild, moderate, and severe faults. Air circuit leakage fault simulation is achieved by modifying the air pressure attenuation parameters of the air spring cavity; sensor drift / bias fault simulation is achieved by modifying the simulated parameters of height / air pressure / temperature; valve body jamming fault simulation is achieved by fixing the valve's open / closed state in the model; and communication anomaly fault simulation is achieved by interrupting signal transmission. It covers common physical fault scenarios of air suspension, and gradient fault testing can comprehensively verify the ECU's response capability under different fault levels, improving test coverage.

[0080] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. An air suspension functional-level simulation and fault injection testing system, characterized in that, include: The host computer is used to configure test conditions, set fault injection strategies, and sampling parameters. The real-time simulation platform has a built-in vehicle model and an air suspension functional level model. The air suspension functional level model includes a dual-chamber air spring functional level model and an adjustable damping shock absorber functional level model. The real-time simulation platform is used to realize the physical state calculation of the air suspension, real-time valve state determination, and dynamic updating of model parameters. The load board group serves as the electrical interface connecting the real-time simulation platform and the air suspension controller, and includes a valve system load board, a PSI5 height signal board, an analog voltage board, and a resistance analog board. Each independent channel of the valve system load board integrates a load network composed of inductors and resistors. The electrical parameters of the load network are calibrated to match the impedance characteristics of the actual vehicle solenoid valve coil, and are used to equivalently simulate the load of the actual vehicle solenoid valve. A current acquisition node is set on each equivalent load branch to collect the drive current output by the air suspension controller in real time and convert it into a digital quantity, which is then transmitted back to the real-time simulation platform via the communication bus. The air suspension controller, which is the controller under test, is used to receive the sensor signals simulated by the load board group, generate valve system drive commands according to the built-in control logic, and output drive current to the valve system load board. The real-time simulation platform determines the valve state based on the measured current value returned by the valve system load board, and updates the air circuit connection relationship and damping force parameters of the air suspension functional level model based on the determined valve state, recalculates the suspension mechanical response and feeds it back to the vehicle model.

2. The air suspension functional-level simulation and fault injection testing system according to claim 1, characterized in that: The multi-channel structure of the valve system load board covers all actuator drive circuits of the air suspension, including the air pump relay, air tank valve, exhaust valve, and height valve, stiffness valve and continuous damping control solenoid valve at the four suspension corners; the equivalent load circuit of each channel uses a resistor and an inductor connected in series to form an equivalent load, and a sampling resistor is connected in series at the front end of the main circuit. The circuit current is calculated by collecting the voltage drop across the sampling resistor.

3. The air suspension functional-level simulation and fault injection testing system according to claim 2, characterized in that: The valve system load board integrates a controllable short-circuit branch on a specific channel. According to the software instructions of the host computer or real-time simulation platform, it actively triggers the injection of electrical faults to short circuit to power supply or to ground at a specified time to verify the fault diagnosis and fault-tolerant control capabilities of the air suspension controller.

4. The air suspension functional-level simulation and fault injection testing system according to claim 3, characterized in that: The functional level model of the dual-chamber air spring replicates the air circuit topology of the real vehicle's dual-chamber air spring, including an air supply assembly and four corner dual-chamber air springs; the air supply assembly includes an air pump, an exhaust valve, an air tank, and an air tank valve; each air spring corresponds to a height valve that controls the inflation and deflation of air and a stiffness valve that controls the opening and closing of the main and auxiliary chambers; the working state of all valves is determined by the real-time simulation platform based on the measured current collected by the valve system load board and drives the synchronous switching of the air circuit state in the model.

5. The air suspension functional-level simulation and fault injection testing system according to claim 4, characterized in that: The adjustable damping shock absorber functional level model is a simulation model of an independent shock absorber configured at the four suspension corners of the vehicle. Each model is a lookup table mapping module containing the relationship between current, shock absorber compression speed and damping force. The real-time simulation platform inputs the measured drive current of the continuous damping control solenoid valve collected by the valve system load board and the real-time compression speed of the shock absorber output by the vehicle model into the lookup table module to calculate the current damping force and feed it back to the vehicle model.

6. The air suspension functional-level simulation and fault injection testing system according to claim 5, characterized in that: The system supports physical fault injection by modifying model parameters through the real-time simulation platform. Fault types include gas leakage, sensor drift / bias, valve body jamming, and communication abnormality. Among them, the air leakage fault is achieved by modifying the air pressure attenuation parameter of the air spring cavity, the sensor drift / bias fault is achieved by modifying the simulated signal parameters of altitude, air pressure, and temperature, the valve body jamming fault is achieved by fixing the valve opening and closing state in the model, and the communication abnormality fault is achieved by interrupting signal transmission.

7. The air suspension functional-level simulation and fault injection testing system according to claim 6, characterized in that: The PSI5 height signal board receives the air spring height values ​​at each corner point calculated and output by the real-time simulation platform based on the vehicle model, generates a height simulation signal consistent with the actual vehicle height sensor protocol, and sends it to the air suspension controller; the analog voltage board receives the air spring air pressure analog voltage signal converted by the real-time simulation platform and outputs it to the air suspension controller. The resistance simulation board simulates the signal characteristics of a real vehicle temperature sensor by changing the resistance value and is connected to the temperature sensor interface of the air suspension controller.

8. The air suspension functional-level simulation and fault injection testing system according to claim 7, characterized in that: The real-time simulation platform determines the valve state based on a preset current threshold or a specific current value: when the current value is zero, the valve is determined to be closed; when the current value is greater than the preset threshold, the valve is determined to be open. The continuously damped control solenoid valve determines the continuous adjustment state based on the specific current value.

9. The air suspension functional-level simulation and fault injection testing system according to claim 8, characterized in that: After the single-channel input air suspension controller's drive current of the valve system load board is received, it flows through a series 2000Ω sampling resistor and the load network. A current acquisition node is connected in parallel across the sampling resistor. The acquired voltage signal is amplified, filtered, and converted from analog to digital to form measured current data, which is output to the 485 differential communication bus and uploaded to the real-time simulation platform. This measured current data serves as the sole basis for the real-time simulation platform to determine the corresponding valve's opening / closing status or operating position. At the same time, an indicator light is connected in parallel across the load network to output a status indication signal based on the current flow. The inductance of the load network includes 23mH and 12mH, and the resistive elements of the load network include 7Ω, 16Ω and 4Ω.

Images