Hardware-in-the-loop test bench and test methods for steer-by-wire systems in commercial vehicles

Abstract

This application discloses a hardware-in-the-loop test bench and test method for a steer-by-wire system for commercial vehicles, including: a road feel simulation module (1) capable of switching between manual driving input mode and automated driving input mode; a steering execution module (2) capable of switching the output end of the steering gear to align with either a direct-drive load (3.1) or a linkage load (3.2) according to the test conditions; a resistance simulation module (3) including a direct-drive load (3.1) and a linkage load (3.2) with torque amplified by a reducer; a power supply and monitoring module (4) used to supply power to the various devices in the test bench and monitor electrical safety; a test bench frame (5); and a control system, which has a built-in vehicle dynamics model and control strategy. This application meets heavy-load requirements, has high accuracy in high-frequency dynamic testing, adopts dual load switching, has high test compatibility and testing efficiency, adopts dual input mode switching, and has a wide range of application scenarios.

Description

Technical Field

[0001] This application belongs to the field of automotive simulation testing technology, specifically relating to a hardware-in-the-loop test bench and test method for steer-by-wire systems of commercial vehicles. Background Technology

[0002] Steer-by-Wire (SBW) is a core technology for intelligent connected vehicles. It replaces the steering shaft in traditional mechanical steering systems with an electronic control unit and actuators, transmitting electrical signals from steering wheel commands to wheel steering actions. Because electrical signal transmission has a faster response time than mechanical connections, SBW provides more precise steering control for intelligent driving. Simultaneously, the system can adjust steering assist characteristics in real time based on vehicle speed, road conditions, and other factors, improving driving comfort and handling.

[0003] The steer-by-wire system for commercial vehicles is a core component of the intelligent chassis. Developing steer-by-wire systems and chassis components for commercial vehicles is crucial for the transformation of automotive transportation from traditional to intelligent and efficient methods, and is of great significance for improving road traffic safety. The market demand for mass production of steer-by-wire systems for commercial vehicles is increasingly urgent. Compared to steer-by-wire systems for passenger vehicles, commercial vehicles, due to their larger size, wider range of load variations, and more complex operating conditions (such as heavy-load uphill driving, low-speed port transshipment, and high-speed trunk line transportation), exhibit significant differences in load characteristics, control precision, and reliability requirements for their steer-by-wire systems.

[0004] In the development of SBW systems, real-vehicle testing presents challenges such as high risk, high cost, long cycle, low efficiency, difficulty in reproducing extreme conditions (e.g., sensor failure, motor overload), and the inability to synchronize software iteration with testing and verification. To address these issues, the development of Hardware-in-Loop (HIL) test benches is the result of the combined effects of the electronic and intelligent evolution of automotive steering systems and the innovation of testing technologies. Its core is to construct a closed-loop test system in a laboratory environment that combines a "real controller + virtual / semi-real vehicle environment," enabling rapid completion of control strategy design, functional logic verification, and basic performance simulation in a purely virtual environment.

[0005] However, existing hardware-in-the-loop test benches for steer-by-wire systems only meet the testing requirements of passenger vehicles and cannot adapt to the testing requirements of commercial vehicles. Steer-by-wire systems for commercial vehicles involve multi-domain coupling (mechanical, electronic, software, and communication), and traditional testing cannot cover all operating conditions. Technical deficiencies in load simulation, hardware compatibility, and scenario adaptation have affected the industrialization process of intelligent chassis technology for commercial vehicles. Summary of the Invention

[0006] The purpose of this application is to provide a hardware-in-the-loop test bench for steer-by-wire systems in commercial vehicles, and a hardware-in-the-loop test method for steer-by-wire systems in commercial vehicles. This application meets the requirements of heavy load, has high accuracy in high-frequency dynamic testing, adopts dual load switching, has high test compatibility and test efficiency, adopts dual input mode switching, and has a wide range of application scenarios.

[0007] The technical solution adopted in this application is: A hardware-in-the-loop test bench for steer-by-wire systems in commercial vehicles includes: The road feel simulation module 1 is used to receive driving input for steering and provide feedback to the driver on the steering wheel's return resistance, enabling switching between manual driving input mode and automated driving input mode. Steering execution module 2, as the steer-by-wire execution module for commercial vehicles, can switch the output of the steering gear to align with either the direct load 3.1 or the linkage load 3.2 according to the test conditions and maintain the position locked after switching the load; The resistance simulation module 3 is used to simulate the steering resistance experienced by the wheel when it is traveling on the road surface, including the direct drag load 3.1 with torque amplified by the reducer and the linkage load 3.2. Power supply and monitoring module 4 is used to supply power to the various devices in the test bench and monitor electrical safety. The test bench frame 5, as the test bench frame, can reliably provide rigid support for high-torque high-frequency dynamic tests; The control system is used to perform closed-loop control of the three components based on the data uploaded by the road feel simulation module 1, the steering execution module 2, and the resistance simulation module 3. It has a built-in vehicle dynamics model and control strategy. The vehicle dynamics model can perform multi-degree-of-freedom real-time simulation calculations based on the virtual running state in the current simulation scenario, generate vehicle dynamic parameters, and inject them into the control strategy. The control strategy can convert the vehicle state in the simulation scenario into control commands for each actuator.

[0008] Preferably, the road feel simulation module 1 includes a driver assembly 1.1 and a road feel simulator 1.2. The driver assembly 1.1 includes an automatic input motor 1.1.1, a manual input steering wheel 1.1.2, and a steering angle torque sensor 1.1.3. The road feel simulator 1.2 includes a road feel simulation motor 1.2.1, a worm gear reducer 1.2.2, and a road feel simulation motor controller 1.2.3. The manual input steering wheel 1.1.2 has a mechanical connection and locking mechanism at its center spline for detachably and rigidly locking to the output shaft of the automatic input motor 1.1.1. When unlocked, it switches to manual driving input mode. The steering shaft of the manual input steering wheel 1.1.2 is directly connected to the road feel simulator 1.2, allowing the driver to directly input the steering wheel. When the steering angle and torque are engaged, the system switches to automated driving input mode. The automatic input motor 1.1.1 can precisely and automatically drive the steering shaft of the manual input steering wheel 1.1.2. The steering angle and torque sensor 1.1.3 is connected in series on the steering shaft of the manual input steering wheel 1.1.2. The output end of the road feel simulation motor 1.2.1 is connected to the worm gear reducer 1.2.2, and the output shaft of the worm gear reducer 1.2.2 is connected to the steering shaft of the manual input steering wheel 1.1.2. The road feel simulation motor controller 1.2.3 is used to calculate the required return torque in real time according to the preset road feel simulation control strategy, and drive the road feel simulation motor 1.2.1 to apply the reverse torque to provide the driver with a realistic steering feel.

[0009] Preferably, in the manual driving input mode, the interaction between the control system and the road feel simulation module 1 is as follows: the driver operates the manual input steering wheel 1.1.2, the steering angle torque sensor 1.1.3 collects the movement of the manual input steering wheel 1.1.2 in real time and sends the steering angle torque signal of the manual input steering wheel 1.1.2 to the road feel simulation motor controller 1.2.3. The road feel simulation motor controller 1.2.3 internally calculates the current steering angle torque signal, and after receiving the vehicle speed signal from the control system, it outputs the target angle and corresponding target resistance torque command unidirectionally to the road feel simulation motor 1.2.1, driving the road feel simulation motor 1.2.1 to generate torque to simulate real road feel and match the feedback feel of driving conditions in commercial vehicle simulation scenarios. At the same time, the road feel simulation module 1 uploads the current of the road feel simulation motor 1.2.1 and the steering angle torque signal of the manual input steering wheel 1.1.2, which are collected in real time at its underlying layer, to the control system as the input boundary for the next displacement and attitude calculation of the vehicle dynamics model.

[0010] Preferably, the steering actuation module 2 includes a steering actuator 2.1 and a load switching mechanism 2.2. The steering actuator 2.1 includes a recirculating ball steering gear 2.1.1, an angle sensor 2.1.2, a steering actuation motor 2.1.3, and a steering actuation motor controller 2.1.4. The load switching mechanism 2.2 includes a steering gear fixing device 2.2.1, a switching slide 2.2.2, and a locking mechanism 2.2.3. The steering actuation motor 2.1.3 is mechanically connected to the input end of the recirculating ball steering gear 2.1.1, and the angle sensor 2.1.2... 1.2 is used to measure the actual rotation angle of the output shaft of the recirculating ball steering gear 2.1.1; the steering actuator 2.1 is mounted on the switching slide 2.2.2 via the steering gear fixing device 2.2.1. The switching slide 2.2.2 is slidably mounted on the test bench frame 5. By translating the switching slide 2.2.2, the output end of the recirculating ball steering gear 2.1.1 can be aligned with either the direct load 3.1 or the rod load 3.2. The locking mechanism 2.2.3 is used to lock the switching slide 2.2.2 after it has moved to the target position.

[0011] Preferably, the interaction between the control system and the steering execution module 2 is as follows: the control system sends the vehicle speed signal under the current simulation environment to the steering execution motor controller 2.1.4 to meet the steering execution motor controller 2.1.4's requirements for table lookup and logical judgment of the vehicle status. The steering execution motor controller 2.1.4 outputs a command to drive the steering execution motor 2.1.3 to drive the recirculating ball steering gear 2.1.1 to steer. At the same time, the steering execution module 2 uploads the current of the steering execution motor 2.1.3 and the actual steering angle signal measured by the angle sensor 2.1.2, which are collected in real time at the bottom layer, to the control system for evaluating the control accuracy, response delay and overshoot of the system under test under simulated conditions.

[0012] Preferably, the test bench frame 5 includes an actuator mounting bracket 5.1 and a platform 5.2; the actuator mounting bracket 5.1 includes a base 5.1.1, a flange connection seat 5.1.2 and a shock-absorbing support mechanism 5.1.3, and each load and motor in the test bench is fixed to the base 5.1.1 through the flange connection seat 5.1.2 and the bottom is equipped with a shock-absorbing support mechanism 5.1.3; the actuator mounting bracket 5.1 and the switching slide 2.2.2 are mounted on the platform 5.2.

[0013] Preferably, in the resistance simulation module 3: the direct load 3.1 includes a direct load motor 3.1.1, a torque sensor 3.1.2, and a direct load reducer 3.1.3. When the output end of the steering gear is aligned with the direct load 3.1, the output end of the direct load motor 3.1.1 is amplified by the direct load reducer 3.1.3 and then coaxially connected with the rocker arm shaft of the steering gear to simulate a pure torque load. The torque sensor 3.1.2 is used for closed-loop monitoring of torque. The linkage load 3.2 includes a wheel-end load simulation motor 3.2.1, a steering tie rod mechanism 3.2.2, a thrust sensor 3.2.3, and a linkage load reducer 3.2.4. When the output end of the steering gear is aligned with the linkage load 3.2, the rotational motion of the wheel-end load simulation motor 3.2.1 is converted into linear thrust by the linkage load reducer 3.2.4 and acts on the steering tie rod mechanism 3.2.2 to simulate the spatial force characteristics of the chassis linkage mechanism. The thrust sensor 3.2.3 is used to monitor the push-pull force.

[0014] Preferably, the interaction between the control system and the resistance simulation module 3 is as follows: When the direct-drive load 3.1 is selected as the resistance simulation condition, the control system sends the target torque to the direct-drive load motor 3.1.1 according to the test requirements and receives the real-time torque uploaded by the torque sensor 3.1.2. The control system corrects the error through a closed-loop control algorithm to ensure the resistance application accuracy under the current condition. When the rod load 3.2 is selected as the resistance simulation condition, the vehicle dynamics model of the control system calculates the complex frictional resistance and self-aligning torque generated between the current virtual tire and the ground, and converts it into a target push-pull force, which is sent to the wheel-end load simulation motor 3.2.1. The control system also receives the real-time push-pull force uploaded by the thrust sensor 3.2.3. The control system corrects the error through a closed-loop control algorithm to monitor the resistance application accuracy under the current condition.

[0015] Preferably, the power supply and monitoring module 4 includes a multi-voltage DC power supply device 4.1 and a safety emergency stop module 4.2. The multi-voltage DC power supply device 4.1 can provide the required DC voltages for the controllers, sensors and motors at all levels in the test bench. The safety emergency stop module 4.2 includes a global emergency stop button, which is connected in series in the main control circuit of the test bench. When pressed, it can simultaneously cut off the enable and power supply of all actuating motors.

[0016] A hardware-in-the-loop testing method for steer-by-wire systems in commercial vehicles, based on the aforementioned hardware-in-the-loop test bench for steer-by-wire systems in commercial vehicles, includes the following steps: S1. Load selection: Based on the chassis characteristics of the commercial vehicle, switch the output end of the steering gear to select either a direct-drive load 3.1 or a linkage load 3.2 and keep the position locked after switching the load; S2. Input mode selection: Depending on the test conditions, switch the road feel simulation module 1 to select manual driving input mode or automated driving input mode; S3. Environment and System Initialization: Power supply and monitoring module 4 is started to supply power to each device in the test bench, load the vehicle dynamics model and control strategy into the control system, configure the simulation scenario parameters, and complete the initialization of the control system; S4. Test closed-loop operation and data interaction: S4.1 Feedforward command issuance: The control strategy calculates the target turning angle trajectory based on the test conditions and sends the turning angle command to the road sense simulation module 1 to drive the steering wheel to turn precisely; S4.2 Steering Execution and Status Reporting: After the steering wheel is turned, the steering execution module 2 receives the target turning angle signal and the collected steering wheel signal, drives the steering gear to push the load according to the control strategy, and uploads its own status to the control system; S4.3 Resistance calculation and following closed loop: The vehicle dynamics model calculates the ground friction resistance and the self-aligning torque in real time based on the received actual turning angle, vehicle speed and vehicle load, and sends the target resistance command to the resistance simulation module 3. The resistance simulation module 3 generates the corresponding reverse thrust and feeds back the actual resistance signal to the control system to form torque following closed loop control. S5. Low-level current cross-monitoring: During the test, the actual current data of the steering actuator motor in steering actuator module 2 and the target feedback current data of the road sense simulation motor in road sense simulation module 1 are extracted and recorded simultaneously. The control system compares the waveforms of the two to verify whether there is distortion, overshoot or communication delay in the torque transmission logic of the steer-by-wire system under extreme load and rapid dynamic response conditions, and generates a collaborative test report.

[0017] The beneficial effects of this application are: This application meets heavy-load requirements and offers high accuracy in high-frequency dynamic testing: the test bench frame 5 reliably provides rigid support for high-torque high-frequency dynamic testing. Both the direct-drive load 3.1 and the linkage load 3.2 amplify torque through reducers. Compared to traditional steering system test benches built based on passenger car standards, this completely solves the shortcomings of benches prone to elastic deformation and insufficient torque output under heavy load conditions in commercial vehicles, providing a foundation for achieving highly realistic and accurate simulation of heavy-load road feel and steer-by-wire system testing for commercial vehicles. This application employs dual-load switching, resulting in high test compatibility and efficiency: the steering execution module 2 can switch the output end of the steering gear to align with either the direct-drive load 3.1 or the linkage load 3.2 according to the test conditions, and maintains a locked position after load switching. Compared to test benches that can only provide single-load switching, this approach offers superior performance. A traditional test bench with pure torque loading or unidirectional tie rod loading can simultaneously meet both pure torque following tests and complex chassis spatial kinematic interference tests on a single device. This not only significantly improves the testing efficiency when changing steering gears of different commercial vehicles, but also ensures that no displacement or excessive vibration occurs during high torque tests of commercial vehicles. Furthermore, it significantly reduces the equipment's footprint and procurement costs. This application adopts a dual-input mode switching, covering a wide range of application scenarios: The road feel simulation module 1 of this application can realize hardware-level switching between manual driving input mode and automated driving input mode. It can efficiently accommodate both human-in-the-loop (DIL) subjective evaluation and hardware-in-the-loop (HIL) objective automated testing modes, providing a solid experimental foundation for the rapid verification and iteration of autonomous driving steering algorithms for commercial vehicles. Attached Figure Description

[0018] Figure 1 This is a block diagram of a hardware-in-the-loop test bench for a commercial vehicle steer-by-wire system in this application, excluding the control system.

[0019] Figure 2 This is a block diagram showing the interaction between the control system and other modules in this application. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0021] The features and performance of this application will be further described in detail below with reference to the embodiments.

[0022] Example 1 This embodiment discloses a hardware-in-the-loop test bench for steer-by-wire systems in commercial vehicles, such as... Figure 1 and Figure 2 As shown, it includes a road feel simulation module 1, a steering actuation module 2, a resistance simulation module 3, a power supply and monitoring module 4, a test bench frame 5, and a control system.

[0023] Regarding Road Sensing Simulation Module 1: The road feel simulation module 1 is used to receive steering input and provide feedback to the driver on the steering wheel's return resistance, enabling switching between manual driving input mode and automated driving input mode.

[0024] In this embodiment, preferably, as follows: Figure 1 As shown, the road feel simulation module 1 includes a driver assembly 1.1 and a road feel simulator 1.2. The driver assembly 1.1 includes an automatic input motor 1.1.1, a manual input steering wheel 1.1.2, and a steering angle torque sensor 1.1.3. The road feel simulator 1.2 includes a road feel simulation motor 1.2.1, a worm gear reducer 1.2.2, and a road feel simulation motor controller 1.2.3. The manual input steering wheel 1.1.2 has a mechanical connection and locking mechanism at its center spline, which is used to detachably and rigidly lock with the output shaft of the automatic input motor 1.1.1. When unlocked, it switches to manual driving input mode. The steering shaft of the manual input steering wheel 1.1.2 is directly connected to the road feel simulator 1.2, allowing the driver to directly input the steering wheel. When the steering angle and torque are engaged, the system switches to automated driving input mode. The automatic input motor 1.1.1 can precisely and automatically drive the steering shaft of the manual input steering wheel 1.1.2. The steering angle and torque sensor 1.1.3 is connected in series on the steering shaft of the manual input steering wheel 1.1.2. The output end of the road feel simulation motor 1.2.1 is connected to the worm gear reducer 1.2.2, and the output shaft of the worm gear reducer 1.2.2 is connected to the steering shaft of the manual input steering wheel 1.1.2. The road feel simulation motor controller 1.2.3 is used to calculate the required return torque in real time according to the preset road feel simulation control strategy, and drive the road feel simulation motor 1.2.1 to apply the reverse torque to provide the driver with a realistic steering feel.

[0025] In this embodiment, preferably, in manual driving input mode, the interaction method between the control system and the road feel simulation module 1 is as follows: Figure 2As shown, the driver operates the manual input steering wheel 1.1.2. The steering angle torque sensor 1.1.3 collects the movement of the manual input steering wheel 1.1.2 in real time and sends the steering angle torque signal of the manual input steering wheel 1.1.2 to the road feel simulation motor controller 1.2.3. The road feel simulation motor controller 1.2.3 internally calculates the current steering angle torque signal and receives the vehicle speed signal (including wheel speed, fault and other bus signals) from the control system. Then, it outputs the target angle and corresponding target resistance torque command to the road feel simulation motor 1.2.1 in one direction, driving the road feel simulation motor 1.2.1 to generate torque to simulate the real road feel and match the feedback feel of the driving conditions in the commercial vehicle simulation scenario. At the same time, the road feel simulation module 1 uploads the current of the road feel simulation motor 1.2.1 and the steering angle torque signal of the manual input steering wheel 1.1.2, which are collected in real time at the bottom layer, to the control system as the input boundary for the next displacement and attitude calculation of the vehicle dynamics model.

[0026] Regarding steering execution module 2: As a steer-by-wire actuator module for commercial vehicles, the steering actuator module 2 can switch the output of the steering gear to align with either the direct load 3.1 or the linkage load 3.2 according to the test conditions and maintain the position locked after switching the load.

[0027] In this embodiment, preferably, as follows: Figure 1 As shown, the steering actuation module 2 includes a steering actuator 2.1 and a load switching mechanism 2.2. The steering actuator 2.1 includes a recirculating ball steering gear 2.1.1, an angle sensor 2.1.2, a steering actuation motor 2.1.3, and a steering actuation motor controller 2.1.4. The load switching mechanism 2.2 includes a steering gear fixing device 2.2.1, a switching slide 2.2.2, and a locking mechanism 2.2.3. The steering actuation motor 2.1.3 is mechanically connected to the input end of the recirculating ball steering gear 2.1.1 (the steering actuation motor 2.1.3 is a key test actuator of the test bench). The angle sensor... 2.1.2 The actual rotation angle of the output shaft of the recirculating ball steering gear 2.1.1 is installed on the output shaft of the recirculating ball steering gear 2.1.1; the steering actuator 2.1 is installed on the switching slide 2.2.2 via the steering gear fixing device 2.2.1. The switching slide 2.2.2 can be slidably installed on the test bench frame 5 in the Y-axis direction. By translating the switching slide 2.2.2, the output end of the recirculating ball steering gear 2.1.1 can be aligned with the direct load 3.1 or the rod load 3.2. The locking mechanism 2.2.3 is used to lock the switching slide 2.2.2 after it moves to the target position.

[0028] In this embodiment, preferably, the interaction between the control system and the steering execution module 2 is as follows: Figure 2As shown, the control system sends the vehicle speed signal, including wheel speed and fault signals, to the steering actuator motor controller 2.1.4 under the current simulation environment to meet the steering actuator motor controller 2.1.4's requirements for table lookup and logical judgment of the vehicle status. The steering actuator motor controller 2.1.4 outputs a command to drive the steering actuator motor 2.1.3 to drive the recirculating ball steering gear 2.1.1 to steer. At the same time, the steering actuator module 2 uploads the current of the steering actuator motor 2.1.3 and the actual steering angle signal measured by the angle sensor 2.1.2, which are collected in real time at the bottom layer, to the control system for evaluating the control accuracy, response delay and overshoot of the system under test under simulated conditions.

[0029] Regarding resistance simulation module 3: The resistance simulation module 3 is used to simulate the steering resistance experienced by the wheel when it is traveling on the road surface, including the direct drag load 3.1 with torque amplified by the reducer and the linkage load 3.2.

[0030] In this embodiment, preferably, as follows: Figure 1 As shown, in the resistance simulation module 3: the direct load 3.1 includes a direct load motor 3.1.1, a torque sensor 3.1.2, and a direct load reducer 3.1.3. When the output end of the steering gear is aligned with the direct load 3.1, the output end of the direct load motor 3.1.1 is amplified by the direct load reducer 3.1.3 and then coaxially connected with the rocker arm shaft of the steering gear to simulate a pure torque load. The torque sensor 3.1.2 is used for closed-loop monitoring of torque. The linkage load 3.2 includes a wheel-end load simulation motor 3.2.1, a steering tie rod mechanism 3.2.2, a thrust sensor 3.2.3, and a linkage load reducer 3.2.4. When the output end of the steering gear is aligned with the linkage load 3.2, the rotational motion of the wheel-end load simulation motor 3.2.1 is converted into linear thrust by the linkage load reducer 3.2.4 and acts on the steering tie rod mechanism 3.2.2 to simulate the spatial force characteristics of the chassis linkage mechanism. The thrust sensor 3.2.3 is used to monitor the push-pull force.

[0031] In this embodiment, preferably, the interaction method between the control system and the resistance simulation module 3 is as follows: Figure 2As shown, when the direct-drive load 3.1 is selected as the resistance simulation condition, the control system sends the target torque to the direct-drive load motor 3.1.1 according to the test requirements and receives the real-time torque uploaded by the torque sensor 3.1.2. The control system corrects the error through a closed-loop control algorithm to ensure the resistance application accuracy under the current condition. When the linkage load 3.2 is selected as the resistance simulation condition, the vehicle dynamics model of the control system calculates the complex frictional resistance and self-aligning torque generated between the virtual tire and the ground, and converts it into a target push-pull force, which is sent to the wheel-end load simulation motor 3.2.1. The control system also receives the real-time push-pull force uploaded by the thrust sensor 3.2.3. The control system corrects the error through a closed-loop control algorithm to monitor the resistance application accuracy under the current condition.

[0032] In this embodiment, preferably, the resistance simulation module 3 and the steering gear in the steering execution module 2 are arranged on the same horizontal plane to ensure the coaxiality and mechanical efficiency of power transmission, and to ensure the stability and safety of the test.

[0033] Regarding power supply and monitoring module 4: The power supply and monitoring module 4 is used to supply power to the various devices in the test bench and monitor electrical safety.

[0034] In this embodiment, preferably, as follows: Figure 1 As shown, the power supply and monitoring module 4 includes a multi-voltage DC power supply device 4.1 and a safety emergency stop module 4.2. The multi-voltage DC power supply device 4.1 can provide various DC voltages required for controllers, sensors and motors at all levels in the test bench. The safety emergency stop module 4.2 includes a global emergency stop button, which is connected in series in the main control circuit of the test bench. When pressed, it can simultaneously cut off the enable and power supply of all actuating motors to ensure test safety.

[0035] Regarding test bench frame 5: The test bench frame 5 serves as the test bench frame, providing reliable rigid support for high-torque, high-frequency dynamic tests.

[0036] In this embodiment, preferably, as follows: Figure 1 As shown, the test bench frame 5 includes an actuator mounting bracket 5.1 and a platform 5.2; the actuator mounting bracket 5.1 includes a base 5.1.1, a flange connection seat 5.1.2 and a vibration damping support mechanism 5.1.3. Each load and motor in the test bench is fixed to the base 5.1.1 through the flange connection seat 5.1.2 and the bottom is equipped with a vibration damping support mechanism 5.1.3; the actuator mounting bracket 5.1 and the switching slide 2.2.2 are mounted on the platform 5.2, and the vibration damping support mechanism 5.1.3 can effectively isolate the mechanical vibration generated by high-frequency torque fluctuations.

[0037] Platform 5.2 preferably adopts a T-slot cast iron platform. The actuator mounting bracket 5.1 and the switching slide 2.2.2 are anchored to the T-slot cast iron platform by T-bolts. The cast iron material has excellent shock absorption and structural rigidity, which fully meets the deformation control requirements of large load testing of commercial vehicles.

[0038] Regarding the control system: The control system is used to perform closed-loop control of the three components based on the data uploaded by the road feel simulation module 1, the steering execution module 2, and the resistance simulation module 3. It has a built-in vehicle dynamics model and control strategy. The vehicle dynamics model can perform multi-degree-of-freedom real-time simulation calculations based on the virtual running state in the current simulation scenario, generate vehicle dynamics parameters, and inject them into the control strategy. The control strategy can convert the vehicle state in the simulation scenario into control commands for each actuator.

[0039] The control system establishes bidirectional communication links with the road feel simulation module 1, steering execution module 2, and resistance simulation module 3 through a real-time communication bus (Ethercat bus or CAN bus) and a hard-wired physical interface to achieve high-frequency data interaction (communication cycle is in the millisecond range).

[0040] Based on the above plan: This application meets heavy-load requirements and has high accuracy in high-frequency dynamic testing: the test bench frame 5 provides reliable rigid support for high-torque high-frequency dynamic testing. The torque of both the direct-drive load 3.1 and the linkage load 3.2 is amplified by the reducer. Compared with the traditional steering system test bench based on passenger car standards, it completely solves the shortcomings of the test bench being prone to elastic deformation and insufficient torque output under heavy load conditions of commercial vehicles. It provides a foundation for realizing highly realistic and high-precision simulation of heavy-load road feel and steer-by-wire system testing of commercial vehicles.

[0041] This application employs dual load switching, resulting in high test compatibility and efficiency. The steering execution module 2 of this application can switch the output end of the steering gear to select either the direct-drive load 3.1 or the linkage load 3.2 according to the test conditions, and maintains the position locked after the load is switched. Compared with traditional test benches that can only provide a single pure torque loading or unidirectional linkage loading, it can simultaneously meet the pure torque following test and the complex chassis space kinematic interference test on one set of equipment. This not only significantly improves the test efficiency when changing steering gears of different models of commercial vehicles, but also ensures that no displacement or excessive vibration occurs during the high torque test of commercial vehicles. Furthermore, it significantly reduces the equipment's footprint and procurement cost.

[0042] This application adopts dual input mode switching and has a wide range of application scenarios: The road sense simulation module 1 of this application can realize hardware-level switching between manual driving input mode and automated driving input mode, and can efficiently support both human-in-the-loop (DIL) subjective evaluation and hardware-in-the-loop (HIL) objective automated testing modes, providing a solid experimental foundation for the rapid verification and iteration of autonomous driving steering algorithms for commercial vehicles.

[0043] Example 2 This embodiment discloses a hardware-in-the-loop testing method for steer-by-wire systems in commercial vehicles, based on the hardware-in-the-loop test bench for steer-by-wire systems in embodiment 1 above, including the following steps: S1. Load selection: Based on the chassis characteristics of the commercial vehicle, switch the output end of the steering gear to select either a direct-drive load 3.1 or a linkage load 3.2 and keep the position locked after switching the load; S2. Input mode selection: Depending on the test conditions, switch the road feel simulation module 1 to select manual driving input mode or automated driving input mode; S3. Environment and System Initialization: Power supply and monitoring module 4 is started to supply power to each device in the test bench, load the vehicle dynamics model and control strategy into the control system, configure the simulation scenario parameters, and complete the initialization of the control system; S4. Test closed-loop operation and data interaction: S4.1 Feedforward command issuance: The control strategy calculates the target turning angle trajectory based on the test conditions and sends the turning angle command to the road sense simulation module 1 to drive the steering wheel to turn precisely; S4.2 Steering Execution and Status Reporting: After the steering wheel is turned, the steering execution module 2 receives the target turning angle signal and the collected steering wheel signal, drives the steering gear to push the load according to the control strategy, and uploads its own status to the control system; S4.3 Resistance calculation and following closed loop: The vehicle dynamics model calculates the ground friction resistance and the self-aligning torque in real time based on the received actual turning angle, vehicle speed and vehicle load, and sends the target resistance command to the resistance simulation module 3. The resistance simulation module 3 generates the corresponding reverse thrust and feeds back the actual resistance signal to the control system to form torque following closed loop control. S5. Low-level current cross-monitoring: During the test, the actual current data of the steering actuator motor in steering actuator module 2 and the target feedback current data of the road sense simulation motor in road sense simulation module 1 are extracted and recorded simultaneously. The control system compares the waveforms of the two to verify whether there is distortion, overshoot or communication delay in the torque transmission logic of the steer-by-wire system under extreme load and rapid dynamic response conditions, and generates a collaborative test report.

[0044] The following is an example of a double lane change obstacle avoidance test conducted on a heavy commercial tractor at a speed of 40 km / h. The test steps are as follows: S1. Load Selection: Based on the chassis characteristics of commercial vehicles, a linkage load 3.2 similar to the kinematics of a real chassis is used as the load application form. The tester loosens the locking mechanism 2.2.3, moves the switching slide 2.2.2 to align the output end of the recirculating ball steering gear 2.1.1 with the linkage load 3.2, and then uses the locking mechanism 2.2.3 to lock the switching slide 2.2.2.

[0045] S2. Input Mode Selection: Under obstacle avoidance test conditions, in order to ensure the objectivity and high-precision repeatability of the input, the road feel simulation module 1 selects the automatic input mode. The tester inserts the output shaft of the automatic input motor 1.1.1 into the mechanical connection and locking mechanism at the center spline of the manual input steering wheel 1.1.2, and locks the mechanical connection and locking mechanism, which switches to the automatic driving input mode. The automatic input motor 1.1.1 can accurately and automatically drive the steering shaft of the manual input steering wheel 1.1.2.

[0046] S3. Environment and System Initialization: Construct the vehicle dynamics model and control strategy for a 40-ton heavy commercial vehicle, configure the simulation scenario parameters for the double lane change test (e.g., constant vehicle speed of 40km / h, road surface adhesion coefficient of 0.85, etc.), and after configuration, send the scenario parameters, vehicle dynamics model and control strategy data as a whole to the RCP system via high-bandwidth protocols such as Ethernet or MQTT and compile them into the RCP system (the control system mainly includes the upper-level host computer test software and the lower-level RCP system) to complete the pre-test initialization.

[0047] S4. Test closed-loop operation and data interaction: S4.1 Feedforward Command Issuance: The control strategy calculates the target turning trajectory based on the turning angle amplitude and frequency of the dual lane change standard, and sends the target turning command in the simulation condition to the servo controller of the automatic input motor 1.1.1 through the Ethercat bus at a set message period to drive the steering wheel shaft to rotate precisely.

[0048] S4.2 Steering Execution and Status Reporting: After the steering wheel is turned, the steering angle torque sensor 1.1.3 of the road feel simulation module 1 acquires the steering wheel's steering angle torque signal and transmits it to the road feel simulation motor controller 1.2.3. At the same time, the steering execution motor controller 2.1.4 receives the target steering angle signal from the road feel simulation module 1 through the CAN line connecting the road feel simulation module 1 and the steering execution module 2. According to the control strategy inside the steering execution motor controller 2.1.4, it outputs the target steering angle of the steering execution motor 2.1.3 and drives the steering execution motor 2.1.3 to actuate. The steering execution motor 2.1.3 pushes the external linkage load 3.2 to the target angle through the recirculating ball steering gear 2.1.1. Simultaneously, the controller under test packages the actual current, actual output torque, and actual steering angle data of the steering execution motor 2.1.3 into a standard CAN message and transmits it back to the control system and the road feel simulation motor controller 1.2.3 in real time through the CAN network.

[0049] S4.3 Resistance Calculation and Following Closed Loop: The vehicle dynamics model runs in real time in the control system. Based on the received actual steering angle, vehicle speed, and vehicle load, the dynamic ground friction resistance and lateral return torque generated by the front wheels of the commercial vehicle are calculated at high frequency. This target resistance torque command is sent at high speed to the wheel-end load simulation motor 3.2.1 of the resistance simulation module 3 through the Ethercat real-time communication bus. After the wheel-end load simulation motor 3.2.1 is amplified by the linkage load reducer 3.2.4, it generates a corresponding dynamic reverse thrust applied to the steering tie rod mechanism 3.2.2. At the same time, the actual resistance torque analog voltage signal collected by the thrust sensor 3.2.3 is amplified and filtered by the signal conditioning board and then input to the high-speed A / D acquisition module of the control system, thereby completing high-precision torque following closed-loop control at the bottom layer.

[0050] S5. Low-level current cross-monitoring: During the violent double lane change operation, the control system synchronously extracts and records the message data of the actual current of the steering actuator motor 2.1.3, as well as the target feedback current data of the road feel simulation motor 1.2.1 calculated internally by the system. The control system transmits the high-frequency data to the host computer test software in real time for waveform mapping comparison, thereby verifying whether there is distortion, overshoot or communication delay in the torque transmission logic of the commercial vehicle steer-by-wire system under extreme high load and rapid dynamic response conditions, and finally generates a collaborative test report.

[0051] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A hardware-in-the-loop test bench for steer-by-wire systems in commercial vehicles, characterized in that, include: The road feel simulation module (1) is used to receive steering input and provide feedback to the driver on the steering wheel return resistance, and can realize the switching between manual driving input mode and automatic driving input mode; The steering execution module (2), as the steer-by-wire execution module for commercial vehicles, can switch the output end of the steering gear to select the direct load (3.1) or the linkage load (3.2) according to the test conditions and keep the position locked after switching the load; The resistance simulation module (3) is used to simulate the steering resistance experienced by the wheel when it is traveling on the road surface, including the direct drag load (3.1) with torque amplified by the reducer and the rod load (3.2). The power supply and monitoring module (4) is used to supply power to the various devices in the test bench and monitor electrical safety; The test bench frame (5), as the test bench frame, can reliably provide rigid support for high-frequency dynamic tests with large torque; The control system is used to perform closed-loop control of the three components based on the data uploaded by the road feel simulation module (1), the steering execution module (2), and the resistance simulation module (3). It has a built-in vehicle dynamics model and control strategy. The vehicle dynamics model can perform multi-degree-of-freedom real-time simulation calculation based on the virtual running state in the current simulation scenario, generate vehicle dynamics parameters and inject them into the control strategy. The control strategy can convert the vehicle state in the simulation scenario into control commands for each actuator.

2. The hardware-in-the-loop test bench for steer-by-wire systems in commercial vehicles as described in claim 1, characterized in that: The road feel simulation module (1) includes a driver assembly (1.1) and a road feel simulator (1.2). The driver assembly (1.1) includes an automatic input motor (1.1.1), a manual input steering wheel (1.1.2), and a steering angle torque sensor (1.1.3). The road feel simulator (1.2) includes a road feel simulation motor (1.2.1), a worm gear reducer (1.2.2), and a road feel simulation motor controller (1.2.3). The manual input steering wheel (1.1.2) has a mechanical connection and locking mechanism at its center spline, which is used to rigidly lock the output shaft of the automatic input motor (1.1.1) in a detachable manner. When unlocked, it switches to manual driving input mode. The steering shaft of the manual input steering wheel (1.1.2) is directly connected to the road feel simulator (1.2), allowing the driver to directly... When the steering angle and torque are input, the system switches to automated driving input mode when locked. The automatic input motor (1.1.1) can accurately and automatically drive the steering shaft of the manual input steering wheel (1.1.2). The angle and torque sensor (1.1.3) is connected in series on the steering shaft of the manual input steering wheel (1.1.2). The output end of the road feel simulation motor (1.2.1) is connected to the worm gear reducer (1.2.2). The output shaft of the worm gear reducer (1.2.2) is connected to the steering shaft of the manual input steering wheel (1.1.2). The road feel simulation motor controller (1.2.3) is used to calculate the required return torque in real time according to the preset road feel simulation control strategy and drive the road feel simulation motor (1.2.1) to apply the reverse torque to provide the driver with a realistic steering feel.

3. The hardware-in-the-loop test bench for steer-by-wire systems in commercial vehicles as described in claim 2, characterized in that, In the manual driving input mode, the interaction between the control system and the road feel simulation module (1) is as follows: the driver applies an operation to the manual input steering wheel (1.1.2), the steering angle torque sensor (1.1.3) collects the action of the manual input steering wheel (1.1.2) in real time and sends the steering angle torque signal of the manual input steering wheel (1.1.2) to the road feel simulation motor controller (1.2.3). The road feel simulation motor controller (1.2.3) calculates the current steering angle torque signal internally, and after receiving the vehicle speed signal from the control system, it outputs the target angle and the corresponding target resistance torque command to the road feel simulation motor (1.2.1) in one direction, driving the road feel simulation motor (1.2.1) to generate torque to simulate the real road feel and match the feedback feel of the driving conditions in the commercial vehicle simulation scenario. At the same time, the road feel simulation module (1) uploads the current of the road feel simulation motor (1.2.1) and the steering angle torque signal of the manual input steering wheel (1.1.2) collected in real time at its bottom layer to the control system as the input boundary for the next displacement and attitude calculation of the vehicle dynamics model.

4. The hardware-in-the-loop test bench for steer-by-wire systems in commercial vehicles as described in claim 1, characterized in that: The steering actuator module (2) includes a steering actuator (2.1) and a load switching mechanism (2.2). The steering actuator (2.1) includes a recirculating ball steering gear (2.1.1), an angle sensor (2.1.2), a steering actuator motor (2.1.3), and a steering actuator motor controller (2.1.4). The load switching mechanism (2.2) includes a steering gear fixing device (2.2.1), a switching slide (2.2.2), and a locking mechanism (2.2.3). The steering actuator motor (2.1.3) is mechanically connected to the input end of the recirculating ball steering gear (2.1.1). The angle sensor (2.1.4) is connected to the input end of the recirculating ball steering gear (2.1.1). .1.2) Used to measure the actual rotation angle of the output shaft of the recirculating ball steering gear (2.1.1); the steering actuator (2.1) is mounted on the switching slide (2.2.2) via the steering gear fixing device (2.2.1). The switching slide (2.2.2) can be slidably mounted on the test bench frame (5). By translating the switching slide (2.2.2), the output end of the recirculating ball steering gear (2.1.1) can be aligned with the direct load (3.1) or the rod load (3.2). The locking mechanism (2.2.3) is used to lock the switching slide (2.2.2) after it has moved to the target position.

5. The hardware-in-the-loop test bench for steer-by-wire systems in commercial vehicles as described in claim 4, characterized in that, The interaction between the control system and the steering execution module (2) is as follows: the control system sends the vehicle speed signal under the current simulation environment to the steering execution motor controller (2.1.4) to meet the steering execution motor controller (2.1.4)’s requirements for table lookup and logical judgment of the vehicle status. The steering execution motor controller (2.1.4) outputs a command to drive the steering execution motor (2.1.3) to drive the recirculating ball steering gear (2.1.1) to turn. At the same time, the steering execution module (2) uploads the current of the steering execution motor (2.1.3) and the actual turning angle signal measured by the angle sensor (2.1.2) to the control system in real time to evaluate the control accuracy, response delay and overshoot of the system under test under simulated conditions.

6. The hardware-in-the-loop test bench for steer-by-wire systems in commercial vehicles as described in claim 4, characterized in that: The test bench frame (5) includes an actuator mounting bracket (5.1) and a platform (5.2); the actuator mounting bracket (5.1) includes a base (5.1.1), a flange connection seat (5.1.2) and a shock-absorbing support mechanism (5.1.3). Each load and motor in the test bench is fixed to the base (5.1.1) through the flange connection seat (5.1.2) and the bottom is equipped with a shock-absorbing support mechanism (5.1.3); the actuator mounting bracket (5.1) and the switching slide (2.2.2) are mounted on the platform (5.2).

7. The hardware-in-the-loop test bench for steer-by-wire systems in commercial vehicles as described in claim 1, characterized in that, In the resistance simulation module (3): the direct-drive load (3.1) includes the direct-drive load motor (3.1.1), the torque sensor (3.1.2), and the direct-drive load reducer ( 3.1.3), when the output end of the steering gear is aligned with the direct-drive load (3.1), the output end of the direct-drive load motor (3.1.1) is connected to the direct-drive load reducer ( 3.1.3) After amplifying the torque, it is coaxially connected with the rocker arm shaft of the steering gear to simulate a pure torque load. The torque sensor (3.1.2) is used for closed-loop monitoring of the torque. The linkage load (3.2) includes a wheel-end load simulation motor (3.2.1), a steering tie rod mechanism (3.2.2), a thrust sensor (3.2.3), and a linkage load reducer (3.2.4). When the output end of the steering gear is aligned with the linkage load (3.2), the rotational motion of the wheel-end load simulation motor (3.2.1) is converted into a linear thrust through the linkage load reducer (3.2.4) and acts on the steering tie rod mechanism (3.2.2) to simulate the spatial force characteristics of the chassis linkage mechanism. The thrust sensor (3.2.3) is used to monitor the push and pull forces.

8. The hardware-in-the-loop test bench for steer-by-wire systems in commercial vehicles as described in claim 7, characterized in that, The interaction between the control system and the resistance simulation module (3) is as follows: when the direct-drive load (3.1) is selected as the resistance simulation working condition, the control system sends the target torque to the direct-drive load motor (3.1.1) according to the test requirements and receives the real-time torque uploaded by the torque sensor (3.1.2). The control system corrects the error through the closed-loop control algorithm to ensure the resistance application accuracy under the current working condition. When the linkage load (3.2) is selected as the resistance simulation condition, the vehicle dynamics model of the control system calculates the complex frictional resistance and self-aligning torque generated between the current virtual tire and the ground, and converts it into a target push-pull force to be sent to the wheel-end load simulation motor (3.2.1). The control system also receives the real-time push-pull force uploaded by the thrust sensor (3.2.3). The control system corrects the error through a closed-loop control algorithm to monitor the resistance application accuracy under the current condition.

9. The hardware-in-the-loop test bench for steer-by-wire systems in commercial vehicles as described in claim 1, characterized in that: The power supply and monitoring module (4) includes a multi-voltage DC power supply device (4.1) and a safety emergency stop module (4.2). The multi-voltage DC power supply device (4.1) can provide various DC voltages required for controllers, sensors and motors at all levels in the test bench. The safety emergency stop module (4.2) includes a global emergency stop button, which is connected in series in the main control circuit of the test bench. When pressed, it can simultaneously cut off the enable and power supply of all actuating motors.

10. A hardware-in-the-loop testing method for steer-by-wire systems in commercial vehicles, characterized in that, Based on the hardware-in-the-loop test bench for steer-by-wire systems for commercial vehicles as described in any one of claims 1 to 9, the test includes the following steps: S1. Load selection: Based on the chassis characteristics of the commercial vehicle, switch the output end of the steering gear to select the aligned direct load (3.1) or the linkage load (3.2) and keep the position locked after switching the load; S2. Input mode selection: According to the test conditions, switch the road feel simulation module (1) to select manual driving input mode or automated driving input mode; S3. Environment and System Initialization: Start the power supply and monitoring module (4) to supply power to each device in the test bench, load the vehicle dynamics model and control strategy into the control system, configure the simulation scene parameters, and complete the initialization of the control system; S4. Test closed-loop operation and data interaction: S4.1 Feedforward command issuance: The control strategy calculates the target turning angle trajectory based on the test conditions and sends the turning angle command to the road feel simulation module (1) to drive the steering wheel to rotate precisely; S4.2 Steering Execution and Status Reporting: After the steering wheel is turned, the steering execution module (2) receives the target turning angle signal and the collected steering wheel signal, drives the steering gear to push the load according to the control strategy, and uploads its own status to the control system; S4.3 Resistance calculation and following closed loop: The vehicle dynamics model calculates the ground friction resistance and the return torque in real time based on the received actual turning angle, vehicle speed and vehicle load, and sends the target resistance command to the resistance simulation module (3). The resistance simulation module (3) generates the corresponding reverse thrust and feeds back the actual resistance signal to the control system to form torque following closed loop control. S5. Low-level current cross-monitoring: During the test, the actual current data of the steering motor in the steering execution module (2) and the target feedback current data of the road sense simulation motor in the road sense simulation module (1) are extracted and recorded synchronously. The control system compares the waveforms of the two to verify whether there is distortion, overshoot or communication delay in the torque transmission logic of the tested steer-by-wire system under extreme load and rapid dynamic response conditions, and generates a collaborative test report.

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