Shaft coupling dynamometer and vehicle test method

Abstract

This invention discloses a shaft-coupled dynamometer and a vehicle testing method. The shaft-coupled dynamometer includes: a test bench; a dynamometer mounted on the test bench; the dynamometer connected to the wheel hub axle of the vehicle under test via a connecting flange to transmit the rotation of the wheel hub axle to the dynamometer; and a steering load system mounted on the test bench to apply load force to the steering and return-to-center operations of the vehicle under test. The steering load system has a directional wheel mechanism, the axis of which is located on the vertical mid-plane of the dynamometer. The vertical mid-plane of the dynamometer is a plane along the vertical direction and passing through the axis of the connecting flange. During the steering process of the vehicle under test, the motion trajectory of the directional wheel mechanism of the shaft-coupled dynamometer is a circular arc trajectory, the center of which is the center of the steering motion trajectory of the wheel hub. The shaft-coupled dynamometer disclosed in this invention overcomes the limitations of site conditions and improves the testing effect.

Description

Technical Field

[0001] This invention relates to the field of vehicle testing equipment technology, and in particular to an axle-coupled dynamometer and a whole vehicle testing method. Background Technology

[0002] Real-vehicle testing can not only verify the performance of the whole vehicle and related components, but also verify whether the vehicle has achieved its original design goals.

[0003] Traditional vehicle power testing uses chassis dynamometers or drum test benches. However, these methods cannot truly overcome the shortcomings of chassis dynamometers, such as site requirements, large experimental errors, and the inability to perform steering.

[0004] Traditional chassis dynamometers are complex to install, require specialized testing site renovations, and cannot test vehicle steering processes. While drum test benches do not require as much site space, they still cannot accurately detect vehicle steering processes or output relevant parameters, resulting in poor repeatability. However, when used in conjunction with hardware-in-the-loop devices, they can also be used for testing in the field of autonomous driving.

[0005] Vehicle-in-the-loop simulation and vehicle finite element simulation are important parts of the automotive R&D stage. However, they cannot be used to verify the performance of the whole vehicle and related components, and still cannot replace the real vehicle testing. Therefore, real vehicle testing is still required after the prototype vehicle is manufactured.

[0006] Therefore, how to overcome the limitations of site conditions and improve the test results is an urgent problem to be solved by personnel in this technical field. Summary of the Invention

[0007] In view of this, the present invention provides a shaft-coupled dynamometer to overcome site limitations and improve testing results. The present invention also provides a method for testing a complete vehicle.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A shaft-coupled dynamometer, comprising:

[0010] stand;

[0011] A dynamometer is mounted on the test bench. The dynamometer is connected to the wheel hub and axle of the vehicle under test via a connecting flange to transmit the rotation of the wheel hub and axle of the vehicle under test to the dynamometer.

[0012] A steering load system for applying load force to the steering and return-to-center operations of the vehicle under test, the steering load system being mounted on the test bench;

[0013] The steering load system has a directional wheel mechanism, in which the axis of the directional wheel is located on the vertical mid-plane of the dynamometer. The vertical mid-plane of the dynamometer is a plane along the vertical direction and passing through the axis of the connecting flange. During the steering process of the vehicle under test, the motion trajectory of the directional wheel mechanism of the shaft-coupled dynamometer is a circular arc trajectory, the center of which is the center of the steering motion trajectory of the wheel hub.

[0014] Optionally, in the above-mentioned shaft-coupled dynamometer, the steering load system further includes a directional wheel drive device and a synchronous connection device; the synchronous connection device is located between the directional wheel drive device and the directional wheel mechanism;

[0015] The drive end of the directional wheel drive device is connected to the power input end of the synchronous connection device, and the power output end of the synchronous connection device is connected to the directional wheel mechanism.

[0016] The directional wheel drive device provides load force to the directional wheel of the directional wheel mechanism through the synchronous connection device. The load force serves as the applied force for the wheel hub axle steering and return-to-center operation of the vehicle under test driven by the shaft-coupled dynamometer.

[0017] Optionally, in the above-mentioned shaft-coupled dynamometer, the synchronous connection device

[0018] Includes a first synchronous pulley, a second synchronous pulley, and transmission components;

[0019] The drive end of the directional wheel drive device is connected to the first synchronous wheel, and the center line of the drive end coincides with the axis of the first synchronous wheel;

[0020] The directional wheel of the directional wheel mechanism is connected to the second synchronous wheel, and the axis of the directional wheel coincides with the axis of the second synchronous wheel;

[0021] The transmission component connects the first synchronous pulley and the second synchronous pulley, and the first synchronous pulley and the second synchronous pulley rotate synchronously through the connection of the transmission component.

[0022] Optionally, in the above-mentioned shaft-coupled dynamometer, the directional wheel mechanism further includes a directional wheel mounting frame and a wheel axle; the directional wheel is rotatably mounted on the directional wheel mounting frame via the wheel axle;

[0023] The directional wheel has a pivot mounting hole, and the wheel axle passes through the pivot mounting hole and is circumferentially positioned and connected to the directional wheel.

[0024] The directional wheel mounting bracket has a wheel axle support hole, and the wheel axle is rotatably mounted in the wheel axle support hole;

[0025] The directional wheel mounting bracket is connected to the platform.

[0026] Optionally, in the above-mentioned shaft-coupled dynamometer, the test stand includes:

[0027] A support frame, comprising a first support portion and a second support portion, the first support portion and the second support portion being hinged together, the second support portion being provided with a column, the dynamometer being disposed on the first support portion or the second support portion, and the steering load system being connected to the first support portion or the second support portion;

[0028] The shock absorber has a first connecting end and a second connecting end. The first connecting end is hinged to the first support part, and the second connecting end is hinged to the column. The shock absorber can achieve shock absorption through its extension and retraction, and is used to absorb shock for the entire shaft-coupled dynamometer.

[0029] Rollers for moving the platform are rotatably mounted on the bottom of the support frame;

[0030] The number of rollers is multiple; among the multiple rollers, there is a front roller near the connecting flange and a rear roller near the directional roller mechanism, and the rear roller is a swivel wheel.

[0031] Optionally, the above-mentioned shaft-coupled dynamometer also includes a lifting mechanism for raising and lowering the rear wheel;

[0032] The lifting mechanism is located on the side of the platform near the directional wheel mechanism;

[0033] The lifting mechanism is two in number and is symmetrically arranged on both sides of the directional wheel mechanism;

[0034] The lifting mechanism includes a lifting mounting base and a lifting drive device. The rear wheel is connected to the lifting end of the lifting drive device. The main structure of the lifting drive device is connected to the lifting mounting base. The lifting mounting base is connected to the platform.

[0035] The distance from the rear wheels of the two lifting mechanisms to the axis of the directional wheel mechanism is equal.

[0036] Optionally, in the above-mentioned shaft-coupled dynamometer, the top surface of the lifting mounting base is connected to the main structure of the lifting drive device;

[0037] The lifting mounting base has a clearance through hole through which the drive end of the lifting drive device passes;

[0038] The rear wheel is located on the side of the lifting mounting base that faces away from the main structure of the lifting drive device, and the wheel frame of the rear wheel is fixedly connected to the drive end of the lifting drive device;

[0039] The drive handle of the lifting drive device drives the drive end of the lifting drive device to move up and down in a direction perpendicular to the top surface of the lifting mounting base, thereby driving the rear wheels to move up and down.

[0040] Optionally, in the above-mentioned shaft-coupled dynamometer, the front wheel is located in the first support section, and the rear wheel and the lifting mechanism are located in the second support section.

[0041] Optionally, in the above-mentioned shaft-coupled dynamometer, the directional wheel mechanism further includes bearings, washers, and fasteners;

[0042] The outer wall of the outer ring of the bearing is connected to the hole wall of the wheel axle support hole of the directional wheel mounting bracket, and the inner wall of the inner ring of the bearing is connected to the inner wall of the wheel axle.

[0043] The axle has a shoulder, one side of the washer is in contact with the shoulder, and the other side of the washer is in contact with the end face of the bearing;

[0044] The directional wheel and the second synchronous wheel are sleeved on the axle, and both ends of the axle are locked by the nuts.

[0045] This invention also provides a whole vehicle testing method, including an axle-coupled dynamometer, a measurement and control system, and a simulation system.

[0046] The shaft-coupled dynamometer includes:

[0047] stand;

[0048] A dynamometer is mounted on the test bench. The dynamometer is connected to the wheel hub and axle of the vehicle under test via a connecting flange to transmit the rotation of the wheel hub and axle of the vehicle under test to the dynamometer.

[0049] A steering load system for applying load force to the steering and return-to-center operations of the vehicle under test, the steering load system being mounted on the test bench;

[0050] The steering load system has a directional wheel mechanism, in which the axis of the directional wheel is located on the vertical mid-plane of the dynamometer. The vertical mid-plane of the dynamometer is a plane along the vertical direction and passing through the axis of the connecting flange. During the steering process of the vehicle under test, the motion trajectory of the directional wheel mechanism of the shaft-coupled dynamometer is a circular arc trajectory, the center of which is the center of the steering motion trajectory of the wheel hub.

[0051] The measurement and control system includes a measurement unit and a control unit;

[0052] The simulation system is communicatively connected to the measurement and control system. The simulation system can formulate control parameters based on the parameters measured by the measurement unit and transmit them to the control unit. The control unit controls the operation of the dynamometer and the steering load system based on the control parameters. The shaft-coupled dynamometer is at least one, and at least one shaft-coupled dynamometer is communicatively connected to one of the measurement and control systems and one of the simulation systems.

[0053] This includes:

[0054] The self-aligning torque of the tested vehicle is determined based on the vehicle parameters, which include at least the vehicle's mass, track width, tires, speed, and steering angle.

[0055] The driving force required by the steering load system is determined based on the dynamometer parameters of the shaft-coupled dynamometer. The dynamometer parameters include at least the mass of the dynamometer, the frictional resistance of the dynamometer, and the return torque of the vehicle under test. The frictional resistance of the dynamometer includes at least the frictional resistance between the front wheel of the shaft-coupled dynamometer and the ground, and the frictional resistance between the directional wheel and the ground.

[0056] The driving force required by the directional wheel drive device of the shaft-coupled dynamometer is calculated based on the driving force required by the steering load system, the transmission ratio of the synchronous connection device, and the diameter of the directional wheel.

[0057] The driving force is transmitted to the directional wheel mechanism through the synchronous connection device, driving the shaft-coupled dynamometer to return to center with the steering system of the vehicle under test.

[0058] As can be seen from the above technical solution, the shaft-coupled dynamometer provided by this invention has both the dynamometer and the steering load system mounted on a test bench. The dynamometer is connected to the wheel hub axle of the vehicle under test via a connecting flange, facilitating the transmission of the rotation of the wheel hub axle to the dynamometer. The steering load system is used to simulate the steering and return to center of the vehicle under test and to apply load force. Since the axis of the directional wheel in the directional wheel mechanism is located on the vertical mid-plane of the dynamometer, the axis of the directional wheel and the axis of the connecting flange are located in the same plane, and this plane is the vertical mid-plane of the dynamometer. Therefore, when the vehicle under test turns, it can drive the entire shaft-coupled dynamometer to rotate around the concentric circle of the wheel hub of the vehicle under test. Since the dynamometer is connected to the wheel hub axle of the vehicle under test via the connecting flange, multiple shaft-coupled dynamometers can be set up and connected to the respective wheel hub axles of the vehicle under test for testing, eliminating the need for additional site setup and overcoming site limitations. The directional wheel's connection position relative to the test bench is fixed and it can rotate, ensuring that the circle containing the trajectory of the shaft-coupled dynamometer when the vehicle under test turns (the trajectory of the directional wheel) is concentric with the circle containing the trajectory of the wheel hub on which the shaft-coupled dynamometer is mounted. Under the rotation of the directional wheel itself, the frictional force of the shaft-coupled dynamometer during the wheel hub's turning motion (the rotation of the vehicle under test) is effectively reduced, ensuring that the load force applied by the steering load system acts as a driving resistance, thus improving the detection accuracy and consequently the test results.

[0059] The present invention also provides a whole vehicle testing method, which has the same technical effect as the aforementioned shaft-coupled dynamometer. Attached Figure Description

[0060] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0061] Figure 1 A three-dimensional structural schematic diagram of the shaft-coupled dynamometer provided in an embodiment of the present invention;

[0062] Figure 2 A top view of the shaft-coupled dynamometer provided in an embodiment of the present invention;

[0063] Figure 3 This is a schematic diagram of the main structure of the shaft-coupled dynamometer provided in an embodiment of the present invention;

[0064] Figure 4 This is a right-side structural schematic diagram of the shaft-coupled dynamometer provided in an embodiment of the present invention;

[0065] Figure 5This is a schematic diagram of the structure of the dynamometer provided in an embodiment of the present invention;

[0066] Figure 6 This is a schematic diagram of the structure of the stand provided in an embodiment of the present invention;

[0067] Figure 7 This is a schematic diagram of the lifting mechanism and rear wheel provided in an embodiment of the present invention;

[0068] Figure 8 This is a schematic diagram of the main structure of the steering load system provided in an embodiment of the present invention;

[0069] Figure 9 This is a side view of the steering load system provided in an embodiment of the present invention.

[0070] Figure 10 This is an exploded structural diagram of the steering load system provided in an embodiment of the present invention;

[0071] Figure 11 A cross-sectional structural schematic diagram of the shaft-coupled dynamometer provided in an embodiment of the present invention;

[0072] Figure 12 A top view of the shaft-coupled dynamometer provided in an embodiment of the present invention;

[0073] Figure 13 This is a schematic diagram of the working structure of the shaft-coupled dynamometer provided in an embodiment of the present invention;

[0074] Figure 14 This is a schematic diagram illustrating the working principle of the shaft-coupled dynamometer provided in an embodiment of the present invention.

[0075] Figure 15 This is a schematic diagram illustrating the working principle of the simulated steering resistance and simulated return torque of the shaft-coupled dynamometer provided in an embodiment of the present invention.

[0076] Figure 16 This is another structural schematic diagram of the steering load system provided in an embodiment of the present invention. Detailed Implementation

[0077] This invention discloses a shaft-coupled dynamometer to overcome site limitations and improve testing results. This invention also provides a method for testing a complete vehicle.

[0078] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0079] like Figures 1-15 As shown, this embodiment of the invention provides a shaft-coupled dynamometer, including a test bench 2, a dynamometer 1, and a steering load system 3. The dynamometer 1 is mounted on the test bench 2 and is connected to the wheel hub axle of the vehicle under test via a connecting flange 6 to transmit the rotation of the wheel hub axle of the vehicle under test to the dynamometer 1. The steering load system 3 is mounted on the test bench 2 and is used to apply load force to the steering and return-to-center operations of the vehicle under test. The steering load system 3 has a directional wheel mechanism 11, and the axis a of the directional wheel 112 in the directional wheel mechanism 11 is located on the vertical mid-plane of the dynamometer 1. The vertical mid-plane of the dynamometer is a plane along the vertical direction and passing through the axis b of the connecting flange 6. During the steering process of the vehicle under test, the motion trajectory of the directional wheel mechanism 11 of the shaft-coupled dynamometer is a circular arc trajectory, the center of which is the center of the steering motion trajectory of the wheel hub.

[0080] The shaft-coupled dynamometer provided in this embodiment of the invention has a dynamometer 1 and a steering load system 3 both mounted on a test bench 2. The dynamometer 1 is connected to the wheel hub axle of the vehicle under test via a connecting flange 6, so as to transmit the rotation of the wheel hub axle of the vehicle under test to the dynamometer 1. The steering load system 3 is used to simulate the steering and return to center of the vehicle under test and to apply load force. Since the axis of the directional wheel 112 in the directional wheel mechanism 11 is located on the vertical mid-plane of the dynamometer 1, the axis a of the directional wheel 112 and the axis b of the connecting flange 6 are located in the same plane, and this plane is the vertical mid-plane of the dynamometer 1 set in the vertical direction. Therefore, when the vehicle under test turns, it can drive the entire shaft-coupled dynamometer to rotate around the concentric circle of the wheel hub of the vehicle under test, so that during the turning process of the vehicle under test, the motion trajectory of the directional wheel mechanism 11 of the shaft-coupled dynamometer is an arc trajectory, the center of which is the center of the turning motion trajectory of the wheel hub. The dynamometer 1 is connected to the wheel hub and axle of the vehicle under test via the connecting flange 6. Therefore, multiple shaft-coupled dynamometers can be set up and connected to the respective wheel hubs and axles of the vehicle under test for testing, without the need for additional site setup, thus overcoming site limitations. The directional wheel 112 is fixed in its connection position relative to the test bench 2 and can rotate, ensuring that the circle d (the movement trajectory of the directional wheel 112) of the shaft-coupled dynamometer when the vehicle under test turns is concentric with the circle c (the movement trajectory of the wheel hub on which the shaft-coupled dynamometer is installed). Under the rotation of the directional wheel 112 itself, the motion friction of the shaft-coupled dynamometer during the wheel hub turning motion (rotation of the vehicle under test) is effectively reduced, ensuring that the load force applied by the steering load system 3 serves as driving resistance, improving the detection accuracy, and thus improving the test effect.

[0081] In this embodiment, the steering load system 3 further includes: a steering wheel drive device 12 that drives the steering wheel 112 of the steering wheel mechanism 11 to rotate; and a synchronous connection device 13 that connects the steering wheel drive device 12 and the steering wheel mechanism 11. This arrangement allows the steering wheel drive device 12 to provide a load force to the steering wheel 112 of the steering wheel mechanism 11 via the synchronous connection device 13 upon activation, and this load force serves as the applied force for steering and return-to-center operations.

[0082] The steering and return-to-center operations are specific operations of the vehicle testing system. The force applied during steering is the steering resistance, and the force applied during return-to-center is the return-to-center assist force obtained based on the return-to-center torque. The synchronous connection device 13 includes a first synchronous pulley 131, a second synchronous pulley 132, and a transmission component 133 connecting the first synchronous pulley 131 and the second synchronous pulley 132. The drive end of the directional wheel drive device 12 is connected to the first synchronous pulley 131, and the centerline of the drive end coincides with the axis of the first synchronous pulley 131. The directional wheel 112 is connected to the second synchronous pulley 132, and the axis of the directional wheel 112 coincides with the axis of the second synchronous pulley 132. The transmission component 133 connects the first synchronous pulley 131 and the second synchronous pulley 132, allowing them to rotate synchronously. This configuration achieves synchronous transmission operation.

[0083] Furthermore, the transmission ratio between the first synchronous pulley 131 and the second synchronous pulley 132 is less than 1. Through the above arrangement, the rotational speed of the directional wheel drive device 12 is reduced and transmitted to the directional wheel 112 through the synchronous connection device 13, amplifying the power transmitted from the directional wheel drive device 12 and facilitating adjustment.

[0084] The transmission component 133 is preferably a synchronous belt with a toothed structure, and the first synchronous pulley 131 and the second synchronous pulley 132 are both gear structures with teeth.

[0085] like Figure 16 As shown, in another embodiment, the directional wheel 112 of the driving directional wheel mechanism 11 is coaxially connected to the driving end of the directional wheel drive device 12 via a coaxial connector 14. The coaxial connector 14 can be a coupling or other components.

[0086] In this embodiment, to facilitate the installation and fixing of the directional wheel drive device 12, the directional wheel drive device 12 includes a servo motor 121, a motor base 122, and a fixing member 123 that fixes the main structure of the servo motor 121 to the motor base 122. The motor base 122 is connected to the frame 2. Preferably, the fixing member 123 is a square pin.

[0087] Since the servo motor 121 is used to provide power, after obtaining parameters such as the mass of the vehicle under test, vehicle size, tire parameters, and steering angle (which can be obtained through the steering system of the vehicle under test or the relationship between the steering wheel angle and the wheel angle), the steering resistance and return assist at different vehicle speeds and different steering angles can be obtained by precisely controlling the servo motor 121.

[0088] Furthermore, the directional wheel mechanism 11 also includes a directional wheel mounting frame 111 and a wheel axle 113. The directional wheel 112 is rotatably mounted on the directional wheel mounting frame 111 via the wheel axle 113, and the directional wheel mounting frame 111 is connected to the platform 2. Specifically, the directional wheel 112 has a pivot mounting hole, through which the wheel axle 113 passes and is circumferentially positioned with the directional wheel 112; the directional wheel mounting frame 111 has a wheel axle support hole, through which the wheel axle 113 is rotatably mounted; the directional wheel mounting frame 111 is connected to the platform 2. That is, the directional wheel 112 rotates along a fixed axis via the wheel axle, allowing the directional wheel 112 to be rotatably mounted on the directional wheel mounting frame 111.

[0089] Furthermore, the directional wheel mechanism 11 also includes a bearing 114, a washer 116, and a fastening nut 115; the outer wall of the outer ring of the bearing 114 is connected to the wall of the wheel axle support hole of the directional wheel mounting bracket 111, and the inner wall of the inner ring of the bearing 114 is connected to the inner wall of the wheel axle 113; the wheel axle 113 has a shoulder, one side of the washer 116 is in contact with the shoulder, and the other side of the washer 116 is in contact with the end face of the bearing; the directional wheel 112 and the second synchronous wheel 132 are sleeved on the wheel axle 113, and the two ends of the wheel axle 113 are respectively locked by the fastening nut 115.

[0090] Specifically, the bearing 114 is used to rotatably mount the axle 113 on the directional wheel mounting bracket 111. To ensure the positioning effect, the axle 113 has bearings 114 at both ends, and washers 116 are provided on the axle 113. The two bearings 114 face each other and contact the washers 116. It also includes locking nuts 115, which are connected to both ends of the axle 113 respectively, and the back faces of the two bearings 114 face the locking nuts 115 at both ends of the axle 113 respectively. The middle part of the axle 113 has a positioning shoulder. A washer 116, a bearing 114 and a locking nut 115 are sequentially fitted onto one end of the axle 113. One side of the washer 116 is in positioning contact with the positioning shoulder, and the other side of the washer 116 is in positioning contact with one end face of the bearing 11. The locking nut 115 is in positioning contact with the other end face of the bearing 11. The bearing 114 is positioned in the axial direction of the axle 113 by the threaded connection between the locking nut 115 and the axle 113.

[0091] The axle 113 rotates synchronously with the directional wheel 112 (connected by a key). The second synchronizing wheel 132 is fixedly connected to the axle 113.

[0092] Preferably, a retaining ring 117 is fitted on the axle 113, and the retaining ring 117 is located between the directional wheel 112 and the second synchronous wheel 132.

[0093] Furthermore, the test bench 2 includes a support frame 7, a shock absorber 9, and rollers for moving the test bench 2. The dynamometer 1 is mounted on the support frame 7, and the steering load system 3 is connected to the support frame 7; the rollers are rotatably mounted at the bottom of the support frame 7. This configuration facilitates the movement of the shaft-coupled dynamometer and also simplifies the actual testing operations.

[0094] Specifically, the support frame 7 includes a first support portion 71 and a second support portion 72, the first support portion 71 and the second support portion 72 are hinged together, the second support portion 72 is provided with a column 73, the dynamometer 1 is mounted on the first support portion 71 or the second support portion 72, and the steering load system 3 is connected to the first support portion 71 or the second support portion 72; the shock absorber 9 has a first connecting end and a second connecting end, the first connecting end is hinged to the first support portion 71, and the second connecting end is hinged to the column 73. The shock absorber 9 can achieve shock absorption through its extension and retraction, and is used to absorb shock for the entire shaft-coupled dynamometer.

[0095] The shock absorber 9 is connected at both ends to the first support portion 71 and the second support portion 72, respectively, forming a triangular structure with the shock absorber 9, the first support portion 71, and the second support portion 72. After the steering mechanism of the vehicle under test is turned to a preset angle, the shock absorber 9 adjusts the axis of the dynamometer 1 to the kingpin inclination angle and wheel inclination angle of the vehicle under test. This arrangement facilitates the transmission of torque between the first support portion 71 and the second support portion 72.

[0096] The rollers consist of multiple rollers; among them, there is a front roller 8 near the connecting flange 6 and a rear roller 16 near the directional roller mechanism 11. The rear roller 16 is a swivel wheel. By setting the rear roller 16 as a swivel wheel, the restriction on the movement of the directional roller 112 by the rear roller 16 is reduced, so as to ensure the test effect.

[0097] To further reduce the restriction on the movement of the directional wheel 112, the platform 2 also includes a lifting mechanism 10 for raising and lowering the rear wheel. The lifting mechanism 10 includes a lifting mounting base 14 and a lifting drive device 15. The rear wheel 16 is connected to the lifting end of the lifting drive device 15, the main structure of the lifting drive device 15 is connected to the lifting mounting base 14, and the lifting mounting base 14 is connected to the platform 2. Specifically, the top surface of the lifting mounting base 14 is connected to the main structure of the lifting drive device 15; the lifting mounting base 14 has a clearance through hole for the drive end of the lifting drive device 15 to pass through; the rear wheel 16 is located on the side of the lifting mounting base 14 facing away from the main structure of the lifting drive device 15, and the wheel frame of the rear wheel 16 is fixedly connected to the drive end of the lifting drive device 15; the drive handle of the lifting drive device 15 drives the drive end of the lifting drive device 15 to move up and down in a direction perpendicular to the top surface of the lifting mounting base 14, thereby driving the rear wheel 16 to move up and down.

[0098] In this embodiment, there are two lifting mechanisms 10, symmetrically arranged on both sides of the directional wheel mechanism 11. The lifting mounting bases 14 and their lifting drive devices 15 of the two lifting mechanisms 10 are also symmetrically arranged. Furthermore, the axial distances from the rear wheels 16 of the two lifting mechanisms 10 to the directional wheel mechanism 11 are equal.

[0099] In this embodiment, the lifting drive device 15 is preferably a hand-cranked lifting mechanism.

[0100] The lifting mounting base 14 is used to fix the lifting mechanism 10 to the platform 2. For example... Figure 8 As shown, the lifting mounting base 14 of the lifting mechanism 10 is welded to the frame 2. The main structure of the lifting drive device 15 is connected to the lifting mounting base 14. The rear wheel 16 (universal wheel) is connected to the lifting drive device 15. The distance between the rear wheel 16 (universal wheel) and the ground is controlled by the lifting drive device 15 (hand-cranked lifting mechanism). When the shaft coupling dynamometer is working, the rear wheel 16 (universal wheel) can be raised off the ground to prevent the rear wheel 16 (universal wheel) from interfering with the simulation of steering resistance. When it is necessary to move the shaft coupling dynamometer, the rear wheel 16 (universal wheel) can be lowered to the ground for easy movement.

[0101] like Figure 13 As shown, four dynamometers 1 are connected to the four wheel hubs and axles of the vehicle under test. The axes of the two dynamometers 1 in the rear half of the vehicle under test (bottom of the figure) (axis b of the connecting flange 6) rotate in the direction shown by the arrow. Through the coupling flange, drive shaft and transmission between the sensors inside the dynamometer 1, the wheel speed and torque of different wheels of the vehicle under test are measured.

[0102] like Figure 6 and Figure 8As shown, the main motor 4 of the dynamometer 1 can also apply driving resistance to the vehicle under test through the above-mentioned coupling flange, drive shaft and other components to measure the vehicle's real-time power, torque and speed under different loads. In this state, the vehicle speed can be measured by the speed sensor of the main motor 4, and the torque can be measured by the torque sensor of the dynamometer 1. After the measurement, the real-time power can be calculated.

[0103] Among them, the components between the main motor 4 and the connecting flange 6 are all transmission and detection parts 5.

[0104] With the accelerator or brake pedal depressed on the vehicle under test, measurements can be taken of its acceleration, deceleration, and constant speed. By controlling the main motor 4 to apply different driving resistances, acceleration and deceleration parameters of the vehicle under test under different road conditions can be measured. Similarly, full-vehicle measurements of starting, shifting, and braking can be performed in any location. Real-world testing of autonomous vehicles can also be conducted using hardware-in-the-loop technology, which will not be elaborated upon here.

[0105] The axes of the two dynamometers 1 in the front half of the vehicle under test (upper part of the figure) (axis b of the connecting flange 6) rotate in the direction indicated by the arrows close to the vehicle under test 100, while the directional wheel mechanism 11 rotates in the direction indicated by the arrows away from the vehicle under test 100. This arrangement facilitates the testing of the shaft-coupled dynamometer effect in steering simulation or return-to-center simulation.

[0106] In this embodiment, the test stand 2 also includes a shock absorber 9 for damping the dynamometer 1 on the support frame 7.

[0107] In this embodiment, the main function of the shock absorber 9 is to reduce vehicle vibration during testing, protecting the main motor 4 and the steering load system 3. Furthermore, it enables the axis of the dynamometer 1 to adapt to the kingpin inclination angle and wheel camber angle of the vehicle under test. Figure 7 As shown, the support frame 7 includes a first support portion 71 and a second support portion 72 that are hinged to each other. The front wheel 8 is located on the first support portion 71, and the rear wheel 16 and the lifting mechanism 10 are located on the second support portion 72. The two ends of the shock absorber 9 are connected to the first support portion 71 and the second support portion 72 respectively, so that the shock absorber 9, the first support portion 71 and the second support portion 72 form a triangular structure. The hinge position of the first support portion 71 and the second support portion 72 is one corner of the triangular structure, and the other two corners are the hinge positions of the shock absorber 9 with the first support portion 71 and the second support portion 72. The shock absorption adjustment is achieved by adjusting the extension and retraction of the shock absorber 9.

[0108] This invention also provides a vehicle testing method, including an axle-coupled dynamometer, a measurement and control system, and a simulation system.

[0109] Wherein, the shaft-coupled dynamometer is any one of those described above, that is, the shaft-coupled dynamometer includes at least:

[0110] Stand 2;

[0111] Dynamometer 1 is mounted on stand 2. Dynamometer 1 is connected to the wheel hub and axle of the vehicle under test via a connecting flange 6, so as to transmit the rotation of the wheel hub and axle of the vehicle under test to the dynamometer 1.

[0112] Steering load system 3 is used to apply load force to the steering operation and return-to-center operation of the vehicle under test. Steering load system 3 is mounted on test bench 2.

[0113] The steering load system 3 has a directional wheel mechanism 11. The axis a of the directional wheel 112 in the directional wheel mechanism 11 is located on the vertical mid-plane of the dynamometer 1. The vertical mid-plane of the dynamometer is a plane along the vertical direction and passing through the axis b of the connecting flange 6. During the steering process of the vehicle under test, the motion trajectory of the directional wheel mechanism 11 of the shaft-coupled dynamometer is a circular arc trajectory, and its center is the center of the steering motion trajectory of the wheel hub.

[0114] Furthermore, the measurement and control system has a measurement unit and a control unit;

[0115] The simulation system is connected to the measurement and control system. The simulation system can formulate control parameters based on the parameters measured by the measurement unit and transmit them to the control unit. The control unit controls the operation of the dynamometer and the steering load system based on the control parameters. There is at least one shaft-coupled dynamometer. At least one shaft-coupled dynamometer is connected to a measurement and control system and a simulation system.

[0116] This includes:

[0117] The self-aligning torque of the tested vehicle is determined based on the vehicle parameters, which include at least the vehicle's mass, track width, tires, speed, and steering angle.

[0118] The driving force required by the steering load system is determined based on the dynamometer parameters of the shaft-coupled dynamometer. The dynamometer parameters include at least the mass of the dynamometer, the frictional resistance of the dynamometer, and the return torque of the vehicle under test. The frictional resistance of the dynamometer includes at least the frictional resistance between the front wheel 8 of the shaft-coupled dynamometer and the ground, and the frictional resistance between the directional wheel 112 and the ground.

[0119] The driving force required by the directional wheel drive device 12 of the shaft-coupled dynamometer is calculated based on the driving force required by the steering load system, the transmission ratio of the synchronous connection device 13, and the diameter of the directional wheel 112.

[0120] The driving force is transmitted to the directional wheel mechanism 11 through the synchronous connection device 13, and the drive shaft coupled dynamometer returns to center with the steering system of the vehicle under test.

[0121] The specific usage method of the vehicle testing system for driving development in the laboratory is as follows:

[0122] S1. Connect the vehicle under test 100 to the entire axle coupling dynamometer;

[0123] S2. Connect the signal lines and control lines of the steering load system 3 and the dynamometer 1 to the measurement and control system 300, and connect the communication line of the drive-by-wire system of the vehicle under test 100 to the measurement and control system 300. Connect the measurement and control system 300 to the host computer of the simulation system 400.

[0124] S3. In the virtual scene simulation software in the simulation system 400, a traffic test scenario is built and the working parameters of each dynamic model of the vehicle under test in the traffic test scenario are set. The wheel speed and steering wheel angle signals of the vehicle under test 100 are associated with the model in the traffic test scenario.

[0125] S4. Set the actual technical parameters of the vehicle under test 100 in the simulation system 400, and set the road load simulation parameters of the road load simulation system.

[0126] S5. Based on the pre-established dynamic model of the vehicle under test (longitudinal dynamic model and lateral dynamic model), calculate the driving resistance in real time according to the vehicle dynamic model and the vehicle speed received by the virtual scene simulation software, and calculate the steering resistance or the required return assist in real time according to the vehicle speed and steering wheel angle signal received by the virtual scene simulation software.

[0127] S6. Based on the driving resistance and steering resistance (return-to-center assist) obtained by the simulation system 400, the measurement and control system 300 calculates the speed of the motor in the dynamometer 1 and the steering load system 3 in real time according to the conversion relationship with the corresponding system, converts it into the corresponding control signal, and then sends the control signal to the controller of the corresponding system to control the motor speed and apply the required driving resistance and steering resistance.

[0128] S7. Repeat steps S5 and S6 in real time and record all information in the simulation system, including the steering wheel angle information, speed, motor speed of dynamometer 1, torque sensor information, shaft-coupled dynamometer temperature information, motor speed of the steering load system, and angle sensor information of the shaft-coupled dynamometer, and archive this information for easy comparison and analysis with relevant parameters of the test vehicle obtained under the same actual driving environment. Since the aforementioned shaft-coupled dynamometer has the above-mentioned technical effects, a vehicle testing system with the aforementioned shaft-coupled dynamometer should also have the same technical effects, which will not be elaborated further here.

[0129] The measurement and control system and simulation system can control a single shaft-coupled dynamometer individually, or they can be networked together to control multiple shaft-coupled dynamometers.

[0130] Furthermore, the vehicle testing system includes a first axle-coupled dynamometer for use with the hub axle of the front wheels of the vehicle under test and a second axle-coupled dynamometer for use with the hub axle of the rear wheels of the vehicle under test; the first axle-coupled dynamometer is any of the axle-coupled dynamometers described above.

[0131] Alternatively, the second shaft coupling dynamometer can be any of the shaft coupling dynamometers mentioned above, or the second shaft coupling dynamometer can be set as a shaft coupling dynamometer that does not include the steering load system 3.

[0132] In the first embodiment, multiple shaft-coupled dynamometers are communicatively connected to a measurement and control system and a simulation system. That is, the measurement and control system and the simulation system simultaneously control multiple shaft-coupled dynamometers.

[0133] In the second embodiment, multiple shaft-coupled dynamometers are connected to multiple measurement and control systems and multiple simulation systems in a one-to-one communication manner.

[0134] In the measurement unit of the measurement and control system, the parameters obtained during the measurement of the vehicle under test include the parameters of the shaft coupling dynamometer itself, the parameters of the vehicle under test, the steering angle of the vehicle under test, and the angular velocity of the vehicle under test; the control parameters include the steering resistance and return torque required to control the operation of the steering load system 3.

[0135] like Figure 14 As shown, taking a simulated steering operation as an example, after the driver turns the steering wheel, the steering system of the test vehicle provides significant steering assistance through the vehicle's hydraulic system and motor, which, together with the steering wheel force, forms a steering force e that acts on the steering wheels through the steering arms, achieving steering. For example... Figure 12As shown, the connecting flange 6 of the dynamometer 1 is connected to the hub of the front wheel of the vehicle under test. The steering system 100 of the vehicle under test drives the shaft-coupled dynamometer 200 to make the dynamometer 1 perform a circular motion around the hub. Due to the configuration of the steering load system 3, the rotation trajectory of the directional wheel 112 coincides with the center of the circular motion of the dynamometer 1, reducing the steering resistance provided by the shaft-coupled dynamometer 200 itself during steering. The fact that the rotation trajectory of the directional wheel 112 coincides with the center of the circular motion of the dynamometer 1 reduces the frictional resistance of the shaft-coupled dynamometer. The steering assist provided by the steering assist system of the vehicle under test is a fixed value. The more force is lost on the shaft-coupled dynamometer, the smaller the turning angle of the vehicle under test. For example, if the rotation trajectory of the directional wheel 112 does not coincide with the center of the circular motion of the dynamometer 1, the steering assist system of the vehicle under test will use its maximum value when the steering wheel is turned to 30°, and it will be unable to turn the steering wheel any further. However, because the steering resistance provided by the shaft-coupled dynamometer 200 itself during steering is reduced, there is still steering assist when the steering wheel is turned to 30°, allowing the steering wheel to be turned further, thereby increasing the simulated vehicle steering angle. Furthermore, the retaining ring 117, wheel axle 113, and bearing 115 used in the directional wheel mechanism 11 have very low friction due to their use in conjunction with the bearing 115, further reducing the steering resistance of the shaft-coupled dynamometer 200. By reducing the steering resistance, the vehicle steering angle that the shaft-coupled dynamometer 200 can simulate is effectively increased.

[0136] When steering primarily relies on the steering system of the vehicle under test to provide the steering force e, the shaft-coupled dynamometer 100 relies on its own weight to provide steering resistance through the frictional force generated by the front wheel 8 and the directional wheel mechanism 11. In this case, the steering resistance is a constant value.

[0137] To further improve accuracy, such as Figure 15As shown, in the first embodiment, after obtaining the mass, wheelbase, track width, and tire parameters of the vehicle under test 100, and the steering wheel angle and angular velocity obtainable from the communication between the simulation system and the vehicle under test 100 via the drive-by-wire communication line, the wheel angle and angular velocity are obtained based on the inherent steering wheel rotation angle-wheel angle and angular velocity relationship of the vehicle under test 100. Specifically, an angle sensor installed at the steering wheel can measure the steering wheel's rotation angle and angular velocity. Then, based on the inherent steering wheel rotation angle-wheel angle and angular velocity relationship of the vehicle under test, the wheel angle and angular velocity are obtained. Under the condition of the measured steering angle and angular velocity parameters g, the actual steering angle h of the vehicle under test is calculated. The angular velocity k, the steering assist e provided by the steering assist system 100, and the weight of the vehicle under test and the resistance of the shaft coupling dynamometer are combined to determine the driving force required by the steering load system 3. Then, based on the gear ratio of the first synchronous wheel 131 and the second synchronous wheel 132 in the synchronous connection device 13 and the diameter of the directional wheel 112, the speed and torque required by the servo motor 121 are determined. The servo motor 121 is controlled by the driver to control the steering and speed of the servo motor 121. The output torque of the directional wheel drive device 12 (motor) is transmitted to the directional wheel mechanism 11 through the synchronous connection device 13, so as to provide the shaft coupling dynamometer 200 with real-time control, accurate steering resistance i that conforms to the steering process of different vehicles.

[0138] like Figure 13 As shown, A represents the direction of applied steering resistance, B represents the vehicle's steering direction, C represents the simulated direction of return assist, and D represents the resistance direction of the shaft-coupled dynamometer 200. Taking the test vehicle turning left as an example, when the wheels turn to a preset angle, the tail of the shaft-coupled dynamometer 200 at the left front rotates to the left with the test vehicle. Since the relevant parameters of the test vehicle are known in advance, and the steering angle h and angular velocity k of the vehicle are obtained through communication between the simulation system and the test vehicle 100, the steering resistance required by the steering load system 3 can be calculated. Then, the steering and speed of the directional wheel drive device 12 can be controlled by the driver to obtain a suitable rightward steering resistance, which is applied to the directional wheel mechanism 11 through the synchronous connection device 13, thereby simulating and applying steering resistance to the test vehicle, and thus measuring parameters such as the speed and torque power of the test vehicle when turning. Similarly, the vehicle parameters of the test vehicle under different steering conditions with all four wheels turning on a muddy and potholed road surface can be obtained. Combined with the above straight driving conditions, vehicle parameters under different road conditions, different speeds, and different steering angles can be obtained, which will not be explained in detail here.

[0139] After the steering system of the vehicle under test is turned to the preset angle, the shock absorber 9 on the test bench 2 will cause the axis of the dynamometer 1 to adapt to the kingpin inclination angle and wheel camber angle of the vehicle under test at this time. At this time, the shaft-coupled dynamometer 200 is mounted at the wheel. The frictional resistance of the dynamometer 1 itself is relatively large, which will consume some of the return torque. Therefore, the steering load system 3 needs to apply driving force to counteract the resistance of the dynamometer 1.

[0140] like Figure 15 As shown, by combining relevant parameters such as the weight of the vehicle under test, wheelbase, tires, mass of the test bench 2 of the axle coupling dynamometer 200, front wheel 8, directional wheel 112, and the actual steering angle h of the vehicle under test, the self-centering torque m of the vehicle under test and the self-centering torque j required to be produced by the steering load system 3 can be obtained.

[0141] Specifically, the self-aligning torque m of the tested vehicle is the self-aligning torque derived from the vehicle parameters of the tested vehicle. The self-aligning torque j required to be produced by the steering load system 3 is the self-aligning torque produced by the steering load system 3 applying driving force to counteract the frictional resistance of the dynamometer 1 itself.

[0142] The servo motor 121 is controlled by a driver to control its direction and speed to obtain a corresponding driving force. This force is then transmitted to the directional wheel mechanism 11 via a synchronous connection device 13, applying a driving force to the shaft-coupled dynamometer 200. This allows for the simulation of the return torque of the vehicle after it has turned.

[0143] like Figure 13As shown, A represents the direction of applied steering resistance, B represents the vehicle's steering direction, C represents the simulated direction of return-to-center assist, and D represents the resistance direction of the shaft-coupled dynamometer 200. Taking a left turn as an example, after the vehicle turns to a preset angle, releasing the steering wheel will automatically return the vehicle to center. At this time, the vehicle is in the return-to-center stage after the turn. Due to the large resistance of the test bench 2 of the shaft-coupled dynamometer 200, the return-to-center force is lost due to the resistance. The steering load system 3 simulates a test bench resistance in the opposite direction to eliminate it, thus achieving the effect of the return-to-center force of the vehicle's own structure. Specifically, firstly, the self-centering torque of the tested vehicle can be obtained based on parameters such as vehicle mass, wheelbase, tires, speed, and steering angle. Then, the frictional resistance of the shaft-coupled dynamometer 200 can be calculated based on the mass of the shaft-coupled dynamometer 200, the front wheel 8, the directional wheel 112, and the ground parameters, thereby determining the driving force required by the steering load system. Then, based on the driving force required by the steering load system 3, the gear ratio of the first synchronous wheel 131 and the second synchronous wheel 132 in the synchronous connection device 13, and the diameter of the directional wheel 112, the driving force required by the servo motor 121 can be calculated. Finally, the driving force is transmitted to the directional wheel mechanism 11 through the synchronous connection device 13, driving the shaft-coupled dynamometer 200 to return to center with the steering system of the tested vehicle. The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably.

[0144] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for testing a complete vehicle, characterized in that, It includes a shaft-coupled dynamometer, as well as a measurement and control system and a simulation system. The shaft-coupled dynamometer includes: Stand (2); Dynamometer (1), the dynamometer (1) is set on the stand (2); the dynamometer (1) is connected to the wheel hub axle of the vehicle under test through a connecting flange, so as to transmit the rotation of the wheel hub axle of the vehicle under test to the dynamometer (1). A steering load system (3) is used to apply load force to the steering operation and return-to-center operation of the vehicle under test, and the steering load system (3) is mounted on the test bench (2); The steering load system (3) has a directional wheel mechanism (11). The axis (a) of the directional wheel (112) in the directional wheel mechanism (11) is located on the vertical mid-surface of the dynamometer (1). The vertical mid-surface of the dynamometer is a plane along the vertical direction and passing through the axis (b) of the connecting flange (6). During the steering process of the vehicle under test, the motion trajectory of the directional wheel mechanism (11) of the shaft-coupled dynamometer is a circular arc trajectory, and its center is the center of the steering motion trajectory of the hub. The measurement and control system includes a measurement unit and a control unit; The simulation system is communicatively connected to the measurement and control system. The simulation system can formulate control parameters based on the parameters measured by the measurement unit and transmit them to the control unit. The control unit controls the operation of the dynamometer and the steering load system based on the control parameters. The shaft-coupled dynamometer is at least one, and at least one shaft-coupled dynamometer is communicatively connected to one of the measurement and control systems and one of the simulation systems. This includes: The self-aligning torque of the tested vehicle is determined based on the vehicle parameters, which include at least the vehicle's mass, track width, tires, speed, and steering angle. The driving force required by the steering load system is determined according to the dynamometer parameters of the shaft-coupled dynamometer. The dynamometer parameters include at least the mass of the dynamometer, the frictional resistance of the dynamometer, and the return torque of the vehicle under test. The frictional resistance of the dynamometer includes at least the frictional resistance between the front wheel (8) of the shaft-coupled dynamometer and the ground and the frictional resistance between the directional wheel (112) and the ground. The driving force required by the directional wheel drive device (12) of the shaft-coupled dynamometer is calculated based on the driving force required by the steering load system, the transmission ratio of the synchronous connection device (13) and the diameter of the directional wheel (112). The driving force is transmitted to the directional wheel mechanism (11) through the synchronous connection device (13), driving the shaft-coupled dynamometer to return to center with the steering system of the vehicle under test.

2. The vehicle testing method as described in claim 1, characterized in that, The synchronous connection device (13) is located between the directional wheel drive device (12) and the directional wheel mechanism (11); The drive end of the directional wheel drive device (12) is connected to the power input end of the synchronous connection device (13), and the power output end of the synchronous connection device (13) is connected to the directional wheel mechanism (11). The directional wheel drive device (12) provides load force to the directional wheel (112) of the directional wheel mechanism (11) through the synchronous connection device (13). The load force is applied as the force for the axial coupling dynamometer to drive the wheel hub axle of the vehicle under test to perform steering and return-to-center operations.

3. The vehicle testing method as described in claim 2, characterized in that, The synchronous connection device (13) Includes a first synchronous pulley (131), a second synchronous pulley (132), and a transmission component (133). The drive end of the directional wheel drive device (12) is connected to the first synchronous wheel (131), and the center line of the drive end coincides with the axis of the first synchronous wheel (131). The directional wheel (112) of the directional wheel mechanism (11) is connected to the second synchronous wheel (132), and the axis of the directional wheel (112) coincides with the axis of the second synchronous wheel (132); The transmission component (133) connects the first synchronous pulley (131) and the second synchronous pulley (132), and the first synchronous pulley (131) and the second synchronous pulley (132) rotate synchronously through the connection of the transmission component (133).

4. The vehicle testing method as described in claim 3, characterized in that, The directional wheel mechanism (11) further includes a directional wheel mounting frame (111) and a wheel axle (113); the directional wheel (112) is rotatably mounted on the directional wheel mounting frame (111) via the wheel axle (113); The directional wheel (112) has a pivot mounting hole, and the wheel axle (113) passes through the pivot mounting hole and is circumferentially positioned and connected to the directional wheel (112); The directional wheel mounting bracket (111) has a wheel axle support hole, and the wheel axle (113) is rotatably mounted in the wheel axle support hole; The directional wheel mounting bracket (111) is connected to the platform (2).

5. The vehicle testing method as described in claim 1, characterized in that, The platform (2) includes: The support frame (7) includes a first support part (71) and a second support part (72). The first support part (71) and the second support part (72) are hinged together. The second support part (72) is provided with a column (73). The dynamometer (1) is provided on the first support part (71) or the second support part (72). The steering load system (3) is connected to the first support part (71) or the second support part (72). The shock absorber (9) has a first connecting end and a second connecting end. The first connecting end is hinged to the first support part (71), and the second connecting end is hinged to the column (73). The shock absorber (9) achieves shock absorption through its extension and retraction, and is used to provide shock absorption for the entire shaft-coupled dynamometer. Rollers for moving the platform (2) are rotatably mounted on the bottom of the support frame (7); The number of rollers is multiple; among the multiple rollers, there is a front wheel (8) near the connecting flange (6) and a rear wheel (16) near the directional wheel mechanism (11), and the rear wheel (16) is a swivel wheel.

6. The vehicle testing method as described in claim 5, characterized in that, It also includes a lifting mechanism (10) for raising and lowering the rear wheel (16); The lifting mechanism (10) is located on the side of the platform (2) near the directional wheel mechanism (11); The number of lifting mechanisms (10) is two, and they are symmetrically arranged on both sides of the directional wheel mechanism (11); The lifting mechanism (10) includes a lifting mounting base (14) and a lifting drive device (15). The rear wheel (16) is connected to the lifting end of the lifting drive device (15). The main structure of the lifting drive device (15) is connected to the lifting mounting base (14). The lifting mounting base (14) is connected to the platform (2). The distance from the rear wheel (16) of the two lifting mechanisms (10) to the axis of the directional wheel mechanism (11) is equal.

7. The vehicle testing method as described in claim 6, characterized in that, The top surface of the lifting mounting base (14) is connected to the main structure of the lifting drive device (15); The lifting mounting base (14) has a clearance through hole through which the drive end of the lifting drive device (15) passes; The rear wheel (16) is located on the side of the lifting mounting base (14) facing away from the main structure of the lifting drive device (15), and the wheel frame of the rear wheel (16) is fixedly connected to the drive end of the lifting drive device (15). The drive handle of the lifting drive device (15) drives the drive end of the lifting drive device (15) to move up and down in a direction perpendicular to the top surface of the lifting mounting base (14), thereby driving the rear wheel (16) to move up and down.

8. The vehicle testing method as described in claim 6, characterized in that, The front wheel (8) is located in the first support section (71), and the rear wheel (16) and the lifting mechanism (10) are located in the second support section (72).

9. The vehicle testing method as described in claim 4, characterized in that, The directional wheel mechanism (11) also includes a bearing (114), a washer (116), and a fastening nut (115). The outer wall of the outer ring of the bearing (114) is connected to the hole wall of the wheel axle support hole of the directional wheel mounting bracket (111), and the inner wall of the inner ring of the bearing (114) is connected to the inner wall of the wheel axle (113). The axle (113) has a shoulder, one side of the washer (116) is in contact with the shoulder, and the other side of the washer (116) is in contact with the end face of the bearing; The directional wheel (112) and the second synchronous wheel (132) are sleeved on the axle (113), and the two ends of the axle (113) are respectively locked by the fastening nut (115).

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