Vehicle test platform based on six-degree-of-freedom parallel robot and working method thereof

Abstract

The invention discloses a vehicle test platform based on a six-degree-of-freedom parallel robot and a working method of the vehicle test platform, and belongs to the technical field of vehicle test. The vehicle test platform comprises a gradient adjusting mechanism, a platform lifting mechanism, a fixed platform, a sliding table moving mechanism, a Stewart platform group and a raining mechanism; the slope adjusting mechanism, the platform lifting mechanism and the fixed platform are sequentially arranged on the bottom plate, one end of the sliding table moving mechanism is located in the fixed platform, the sliding table moving mechanism is slidably connected with a Stewart platform set, and the Stewart platform set limits wheels of a to-be-tested vehicle. According to the invention, a comprehensive test platform capable of completing eight types of tests of vehicle centroid measurement, rollover, vibration, road bumping, variable-speed driving, collision, raining and climbing can be constructed, and simulation and execution of various test conditions are realized by using the multi-degree-of-freedom motion capability and a modular structure of the Stewart platform group, so that the test efficiency is remarkably improved, and the test cost is reduced. And integration and multi-functionalization of vehicle research and development and testing are realized.

Description

Technical Field

[0001] This invention relates to the field of vehicle testing technology, and in particular to a vehicle testing platform based on a six-degree-of-freedom parallel robot and its working method. Background Technology

[0002] Comprehensive vehicle performance testing is a crucial step in verifying the safety, reliability, and overall driving quality of a vehicle. Its evaluation indicators cover multiple key dimensions, including rollover stability, center of gravity positioning, vibration response, and collision safety. Currently, common testing methods include real-world road testing, proving ground testing, and indoor simulation testing. While real-world road testing offers realistic conditions, it is highly susceptible to environmental interference, has a long cycle time, and poor repeatability. Proving ground testing also faces limitations such as low testing efficiency and long cycles. Indoor simulation testing, on the other hand, offers advantages such as high repeatability, short cycles, and immunity to external environmental influences. It allows for flexible adjustment of working conditions according to actual needs, analysis of the performance of key components, and optimization and improvement. However, existing indoor simulation test benches are mostly limited to single operating conditions. Rollover test benches, vibration test benches, and hill-climbing test benches are usually set up independently, and a comprehensive platform integrating multiple test types and supporting a complete testing process has not yet been formed. This not only occupies a large amount of testing space but also increases the complexity of overall coordination and scheduling.

[0003] The Stewart platform, a six-DOF parallel robot mechanism, boasts advantages such as high stiffness, high precision, and multi-DOF linkage, and has been widely applied in fields such as flight simulation and precision machining. Through the coordinated movement of six electric actuators, it can achieve high-precision multi-dimensional motion control in space, simulating complex spatial trajectories. With its unique parallel configuration, the Stewart platform effectively meets the needs of multi-condition coupled simulation in vehicle testing, enabling accurate simulation of various complex test conditions such as rollover and vibration. Although existing research has used Stewart platform assemblies in vehicle testing, most solutions employ a single Stewart platform supporting the entire vehicle body. While it can simulate the pitch, roll, and vertical motion of a vehicle, certain limitations remain: a single platform cannot realistically reproduce the road excitation of multi-wheel coupling, and cannot accurately simulate the force differences of each wheel under asymmetrical or rugged road conditions. Furthermore, the entire vehicle mass is concentrated on a single platform, placing extremely high demands on the output force, stiffness, and dynamic response characteristics of the drive unit, increasing system cost and limiting the scope and accuracy of motion simulation. Furthermore, the single Stewart platform group is difficult to flexibly adapt to vehicle models with different wheelbases and track widths, which limits its versatility in multi-vehicle and multi-task testing scenarios.

[0004] Therefore, those skilled in the art urgently need a highly integrated vehicle comprehensive testing platform and its working method that is adaptable to different vehicle models and can complete multiple types of tests in a single site, so as to realize one-stop testing under multiple working conditions and promote the development of vehicle testing technology towards integration and intelligence. Summary of the Invention

[0005] The purpose of this invention is to provide a vehicle testing platform based on a six-degree-of-freedom parallel robot and its operating method. By integrating a slope adjustment mechanism, a platform lifting mechanism, a sliding table movement mechanism, a Stewart platform assembly, and a rain-testing mechanism into a comprehensive platform structure, an integrated testing platform capable of performing eight types of tests: vehicle center of gravity measurement, rollover, vibration, road bumps, variable speed driving, collision, rain, and hill climbing. This comprehensive platform utilizes the multi-degree-of-freedom motion capabilities of the Stewart platform assembly to simulate and execute the aforementioned various test conditions, significantly improving testing efficiency and achieving integration and multi-functionality in vehicle research and development and testing.

[0006] To achieve the above objectives, this invention provides a vehicle testing platform based on a six-degree-of-freedom parallel robot and its operating method, comprising a slope adjustment mechanism, a platform lifting mechanism, a fixed platform, a sliding table moving mechanism, Stewart platform assemblies, and a rain shower mechanism mounted on a base plate. The slope adjustment mechanism, platform lifting mechanism, and fixed platform are sequentially mounted on the base plate. The fixed platform has a hollow structure. The sliding table moving mechanism is positioned close to the fixed platform, with one end of the sliding table moving mechanism located within the fixed platform. The Stewart platform assemblies are slidably connected to the sliding table moving mechanism, and the Stewart platform assemblies are initially located within the fixed platform. The rain shower mechanism is positioned above the other end of the sliding table moving mechanism, and its bottom is fixed to the base plate. The multiple Stewart platform assemblies limit the movement of the wheels of the vehicle under test.

[0007] Preferably, the slope adjustment mechanism includes a base, a hydraulic cylinder, and a ramp. The base is fixedly connected to the base plate, one end of the ramp is hinged to one end of the base, the other end of the base is hinged to the fixed end of the hydraulic cylinder, and the movable end of the hydraulic cylinder is hinged to the bottom of the middle part of the ramp. The platform lifting mechanism includes a platform plate, two oppositely arranged scissor arms, a second base, a guide plate, a connecting shaft, and a second hydraulic cylinder. The second base is fixedly connected to the base plate. The scissor arms are diamond-shaped scissor arms, and the ends of the rods of the two diamond-shaped scissor arms are hinged together by the connecting shaft. One end of the bottom rod of each scissor arm is hinged to one side of the top of the base two. Two oppositely arranged guide plates are fixedly connected to the other side of the top of the base two. The guide plates are horizontally provided with guide grooves. The other ends of the bottom rods of the two scissor arms are respectively slidably connected in the two guide grooves. The bottom of the platform plate is also fixedly connected to two oppositely arranged guide plates. The guide plates are horizontally provided with guide grooves. One end of the top rod of each scissor arm is hinged to one side of the top of the platform plate, and the other end of the top rod of each scissor arm is slidably connected to the guide grooves at the bottom of the two platform plates. The guide plates at the bottom of the platform plate and the guide plates on the base are arranged vertically opposite to each other. The middle part of a connecting shaft at the bottom of the scissor arm is hinged to the fixed end of the second hydraulic cylinder, and the middle part of another connecting shaft at the bottom of the scissor arm is hinged to the movable end of the second hydraulic cylinder. The movable end of the second hydraulic cylinder is located between the guide plates on the base. Initially, the ramp plate is in contact with one side of the platform plate, and the platform plate is flush with the top of the fixed platform.

[0008] Preferably, the sliding mechanism includes guide rails, a rack, a motor, a first slide, a second slide, and a third slide. Two guide rails are adjustablely mounted on the base plate. Two relatively parallel first slides, two relatively parallel second slides, and two relatively parallel third slides are sequentially slidably connected to the two guide rails. A rack is provided on the inner wall of each guide rail. A motor is fixedly connected to the top of each of the first, second, and third slides. The output shaft of the motor is driven by a gear located at the bottom of each of the first, second, and third slides, and the gear meshes with the rack for transmission. A Stewart platform assembly is connected to each of the first, second, and third slides.

[0009] Preferably, the Stewart platform group includes six six-degree-of-freedom parallel robots. Each six-degree-of-freedom parallel robot includes an upper platform, a lower platform, electric push rods, universal joints, and wheel limiting components. The lower platform of each six-degree-of-freedom parallel robot is fixedly connected to two first slides, two second slides, and two third slides, respectively. The top of the lower platform is hinged to the fixed ends of the six electric push rods. The movable ends of the electric push rods are connected to universal joints, which are connected to the bottom of the upper platform. The electric push rods are equipped with load cells, tilt sensors, and displacement sensors. The wheel limiting assembly includes a U-shaped stop, an L-shaped rib, a rubber anti-rollover device, a hanging ring, and an anti-slip cloth. The two U-shaped stops are adjustable and symmetrically arranged on the top of the upper platform. The two L-shaped ribs are also adjustable and symmetrically arranged on the top of the upper platform. A rubber anti-rollover device is fixedly connected to the inner wall of each of the two L-shaped ribs. One side of the rubber anti-rollover device is an arc-shaped surface. The two U-shaped stops, the two L-shaped ribs, and the two rubber anti-rollover devices form a space for placing the wheel. The arc-shaped surface of the wheel contacts the arc-shaped surface of the rubber anti-rollover device, and the two sides of the wheel contact the inner wall of the U-shaped stop. Each of the two L-shaped ribs has a hanging ring fixedly connected to its top, and the top of the upper platform also has four hanging rings fixedly connected to its top. Two of the hanging rings are located on one side of a U-shaped block, and two of the hanging rings are located on one side of another U-shaped block. The four hanging rings are used to wrap the binding rope, which is used to bind the vehicle body. The anti-slip cloth has hooks at both ends, and two of the hooks are respectively hooked onto the hanging rings at the top of the L-shaped ribs to limit the wheel at the top of the arc surface of the wheel.

[0010] Preferably, the upper platform is provided with multiple guide grooves 2 and two guide grooves 3, the extension lines of the guide grooves 2 and 3 are arranged perpendicularly, the bottom of the U-shaped block is provided with a through hole, and the bolt passes through the U-shaped block and the guide groove 2 and is connected with a nut; the bottom of the L-shaped rib is also provided with a through hole, and the bolt passes through the L-shaped rib and the guide groove 3 and is connected with a nut.

[0011] Preferably, the rain shower mechanism includes a frame, water supply pipes, a water pump, and spray heads. The frame is a U-shaped frame, and multiple rows of water supply pipes are provided on the top and sides of the U-shaped frame. Multiple spray heads are evenly arranged in an array on the water supply pipes to spray the top and sides of the vehicle. The water pump is also connected to a water tank and is electrically connected to a controller.

[0012] A working method for a vehicle test platform based on a six-degree-of-freedom parallel robot includes the following steps: Step 1, the overall vehicle test platform is in its initial state, with the Stewart platform group located directly below the bottom of the fixed platform. When the vehicle under test drives into the fixed platform, the sliding table moving mechanism drives the two first sliding tables to move in a straight line parallel to the vehicle's driving direction, thereby moving the six-degree-of-freedom parallel robot on the two first sliding tables horizontally out from directly below the bottom of the fixed platform and keeping it flush with the fixed platform to form a vehicle test plane that connects with the fixed platform. Subsequently, the front axle wheels of the vehicle under test were driven onto the upper platform of two six-degree-of-freedom parallel robots, and the wheel limiting components were operated to position and constrain the front axle wheels. Repeat the above steps to drive the central axle wheels of the vehicle under test onto the upper platforms of the two six-DOF parallel robots on the second slide, and the rear axle wheels onto the upper platforms of the two six-DOF parallel robots on the third slide. Operate the wheel limiting components to perform wheel positioning and constraint in sequence. After completing the vehicle positioning and constraint operation, perform the vehicle center of gravity measurement test, vehicle rollover test, vehicle vibration test, vehicle road bump test, vehicle speed change driving test, vehicle collision test, and vehicle rain test. Step two: Conduct an independent vehicle climbing test using the slope adjustment mechanism and platform lifting mechanism.

[0013] Preferably, the vehicle center of gravity measurement test obtains the three-dimensional coordinates of the center of gravity by calculating the horizontal center of gravity position of the vehicle, measuring the distance of the center of gravity relative to the vehicle centerline, and measuring the height of the center of gravity using the tilt method; The vehicle rollover test is conducted by controlling the lateral movement of the Stewart platform assembly to create a rollover condition. The roll angle is monitored in real time by the tilt sensor and the load change of the right wheel is monitored by the load sensor. The tilting stops when the normal reaction force of the support plane of all the right wheels is zero. At this time, the roll angle of the platform is the maximum roll stability angle when the vehicle tilts to the left. The maximum roll angle value at this time is recorded. The vehicle vibration test includes sinusoidal vibration test and random composite vibration test; the extension and retraction motion of the Stewart platform group is used to simulate various test conditions and simulate the vibration excitation of actual complex road surfaces. The vehicle speed change driving test forms a pitch attitude by controlling the telescopic movement of the Stewart platform group, and generates forward and backward inertial forces by coordinating the linear acceleration and deceleration of the first slide, second slide, and third slide in the same direction, and performs acceleration and deceleration condition test. The vehicle collision test simulates the collision process through the coordinated movement of the sliding platform mechanism and the Stewart platform assembly. The sliding platform mechanism drives the Stewart platform assembly and accelerates the vehicle along the collision direction to a preset initial speed, adjusting the vehicle to a frontal or offset collision posture. Simultaneously, at the moment of collision, the electric push rod of the Stewart platform assembly is controlled to extend rapidly, applying an instantaneous compensating acceleration to the vehicle in the same direction of movement as the first, second, and third sliding platforms, so that the vehicle reaches the preset collision speed. Subsequently, the collision impact and energy absorption process are simulated by braking the first, second, and third sliding platforms and contracting the electric push rod of the Stewart platform assembly according to the deceleration curve. The vehicle rain test uses a coordinated spraying mechanism to simulate typical operating conditions of a vehicle in actual driving through the Stewart platform group, and monitors and records the sealing status of each part.

[0014] Preferably, the vehicle climbing test uses hydraulic cylinder one of the slope adjustment mechanism to adjust the test slope of the ramp plate, and uses hydraulic cylinder two to control the lifting and lowering of the scissor arm to drive the platform plate and the fixed platform to form a continuous test plane, so as to perform the prescribed ramp vehicle climbing test and ramp start test.

[0015] Preferably, the vehicle positioning and constraint operation method includes the following steps: Step 1, Disassembly Preparation: Remove the two L-shaped ribs and two rubber anti-reverse devices, loosen the bolts fixing the two U-shaped blocks, and let the U-shaped blocks move outward along the guide groove of the upper platform. Step 2: Lateral positioning of the wheel. After the vehicle under test drives onto the upper platform of the Stewart platform assembly, move the two U-shaped blocks in the direction of the wheel sidewall so that the sides of the two U-shaped blocks are in close contact with the left and right sidewalls of the wheel. After confirming that the positioning is accurate, tighten the bolts of the two U-shaped blocks to achieve left and right limit of the wheel and prevent lateral slippage. Step 3: Limit the front and rear of the wheel. Adjust the position of the two L-shaped ribs by moving them in the guide groove three in the direction close to the wheel's arc surface, and push the first rubber anti-rollover device to tightly press against the front and rear ends of the wheel. Then, tighten the bolts of the L-shaped ribs to limit the front and rear of the wheel and prevent longitudinal movement. Step four involves anti-slip treatment. Hooks on both sides of the anti-slip cloth are inserted into the hanging rings at the top of the two L-shaped ribs, ensuring the cloth covers the upper part of the tire to increase friction and prevent the wheel from slipping and rolling during the test. Next, safety precautions are taken. The binding rope is threaded through the four hanging rings fixed around the upper platform and wrapped around the chassis beam to prevent the vehicle from accidentally detaching from the platform during the test, providing additional safety protection. After vehicle positioning and constraint are completed, the appropriate test mode is selected according to the test requirements. The control system drives the Stewart platform assembly to perform the corresponding movements for vehicle testing. Step 5: After the test, perform a reset operation, remove the binding ropes on the lifting rings, remove the anti-slip cloth, remove the two L-shaped ribs and two rubber anti-slip devices, loosen the bolts of the two U-shaped blocks, retract the Stewart platform assembly to the fixed platform and drive the vehicle away from the Stewart platform assembly. After the vehicle leaves the test platform system, control the sliding mechanism to drive the Stewart platform assembly to move horizontally and retract it to the bottom directly below the fixed platform.

[0016] The advantages and positive effects of the vehicle testing platform and its working method based on a six-degree-of-freedom parallel robot described in this invention are as follows: (1) This invention achieves a high degree of integration of multiple test functions, completes eight types of test items through one system, and avoids the errors and time costs caused by multiple device switching and repeated positioning in the traditional solution, which greatly improves test efficiency and site utilization.

[0017] (2) The present invention has excellent vehicle adaptability. By adjusting the sliding table spacing and the position and orientation of the Stewart platform group, it can quickly adapt to the testing requirements of different wheel track, wheelbase and vehicle structure, and is applicable to multiple fields such as vehicle research and development, manufacturing testing and performance optimization.

[0018] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of a vehicle testing platform based on a six-degree-of-freedom parallel robot according to the present invention; Figure 2 This is a schematic diagram of the slope adjustment mechanism, platform lifting mechanism, and fixed platform connection structure of the present invention; Figure 3 This is a schematic diagram of the sliding table moving mechanism of the present invention; Figure 4 This is a schematic diagram of the Stewart platform group structure of the present invention; Figure 5 This is a schematic diagram of the wheel limiting component structure of the present invention; Figure 6 This is a schematic diagram of the wheel limiting assembly of the present invention without a wheel installed. Figure 7 This is a schematic diagram of the platform structure of the present invention; Figure 8 This is a schematic diagram of the rain shower mechanism of the present invention; Figure 9 This is a schematic diagram of the working state of the vehicle center of gravity measurement test according to the present invention; Figure 10 This is a schematic diagram of the vehicle rollover test working state of the present invention; Figure 11 This is a schematic diagram of the vehicle vibration test working state of the present invention; Figure 12 This is a schematic diagram of the vehicle of the present invention under road bump test conditions; Figure 13 This is a schematic diagram of the working state of the variable speed driving test of the present invention; Figure 14 This is a schematic diagram of the vehicle collision test working state of the present invention; Figure 15 This is a schematic diagram of the vehicle rain test working state of the present invention; Figure 16This is a schematic diagram of the working state of the vehicle hill-climbing test according to the present invention.

[0020] Figure Labels 1. Slope adjustment mechanism; 101. Base 1; 102. Hydraulic cylinder 1; 103. Ramp plate; 2. Platform lifting mechanism; 201. Platform plate; 202. Scissor arm; 203. Base II; 204. Guide plate; 2041. Guide groove I; 205. Connecting shaft; 206. Hydraulic cylinder II; 3. Fixed platform; 4. Slide moving mechanism; 401. Guide rail; 402. Rack; 403. Motor; 404. First slide; 405. Second slide; 406. Third slide; 5. Stewart platform assembly; 501. Upper platform; 502. Lower platform; 503. Electric push rod; 504. Universal joint; 505. Wheel limit assembly; 5051. U-shaped stop; 5052. L-shaped rib; 5053. Rubber anti-roll bar; 5054. Lifting ring; 5055. Anti-slip cloth; 5056. Wheel; 5057. Guide groove two; 5058. Guide groove three; 5059. Bolt; 6. Rain shower mechanism; 601. Frame; 602. Water supply pipeline; 603. Water supply pump; 604. Sprinkler head; 7. Vehicle to be tested. Detailed Implementation

[0021] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] In this application, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. In case of any inconsistency, the meaning set forth in this specification or derived from the content described herein shall prevail. Furthermore, the terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit the scope of this application.

[0023] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0024] like Figures 1-16 As shown, a vehicle testing platform based on a six-degree-of-freedom parallel robot includes a slope adjustment mechanism 1, a platform lifting mechanism 2, a fixed platform 3, a sliding table moving mechanism 4, a Stewart platform assembly 5, and a rain mechanism 6, all mounted on a base plate. The slope adjustment mechanism 1, platform lifting mechanism 2, and fixed platform 3 are sequentially arranged on the base plate. The fixed platform 3 has a hollow structure. The sliding table moving mechanism 4 is positioned close to the fixed platform 3, with one end of the sliding table moving mechanism 4 located inside the fixed platform 3. The Stewart platform assembly 5 is slidably connected to the sliding table moving mechanism 4, and initially, the Stewart platform assembly 5 is located inside the fixed platform 3. The rain mechanism 6 is positioned above the other end of the sliding table moving mechanism 4, and its bottom is fixed to the base plate. The Stewart platform assembly 5 limits the movement of the wheels of the vehicle 7 under test.

[0025] The slope adjustment mechanism 1 includes a base 101, a hydraulic cylinder 102, and a ramp 103. The base 101 is fixedly connected to the base plate. One end of the ramp 103 is hinged to one end of the base 101. The other end of the base 101 is hinged to the fixed end of the hydraulic cylinder 102. The movable end of the hydraulic cylinder 102 is hinged to the bottom of the middle part of the ramp 103.

[0026] Specifically, hydraulic cylinder 102 is electrically connected to the controller. The controller controls hydraulic cylinder 102 to extend, raising ramp 103. The controller also controls hydraulic cylinder 102 to shorten, slowing down ramp 103.

[0027] The platform lifting mechanism 2 includes a platform plate 201, two oppositely arranged scissor arms 202, a second base 203, a guide plate 204, a connecting shaft 205, and a second hydraulic cylinder 206. The second base 203 is fixedly connected to the base plate. The scissor arms 202 are diamond-shaped scissor arms 202, and the ends of the rods of the two diamond scissor arms 202 are hinged through the connecting shaft 205.

[0028] One end of the bottom rod of each scissor arm 202 is hinged to one side of the top of the base 203. Two opposing guide plates 204 are fixedly connected to the other side of the top of the base 203. The guide plates 204 have horizontally opened guide grooves 2041. The other ends of the bottom rods of the two scissor arms 202 are slidably connected in the two guide grooves 2041 respectively.

[0029] The bottom of the platform plate 201 is also fixedly connected to two opposing guide plates 204. The guide plates 204 are horizontally provided with guide grooves 2041. One end of the top rod of each scissor arm 202 is hinged to one side of the top of the platform plate 201, and the other end of the top rod of each scissor arm 202 is slidably connected in the guide grooves 2041 at the bottom of the two platform plates 201. The guide plates 204 at the bottom of the platform plate 201 and the guide plates 204 on the base are arranged vertically opposite each other.

[0030] The middle part of a connecting shaft 205 at the bottom of the scissor arm 202 is hinged to the fixed end of the second hydraulic cylinder 206, and the middle part of another connecting shaft 205 at the bottom of the scissor arm 202 is hinged to the movable end of the second hydraulic cylinder 206. The movable end of the second hydraulic cylinder 206 is positioned between the guide plates 204 on the base. Initially, the ramp plate 103 contacts one side of the platform plate 201, and the platform plate 201 is flush with the top of the fixed platform 3.

[0031] Specifically, hydraulic cylinder 206 is electrically connected to the controller. The controller controls the movable end of hydraulic cylinder 206 to shorten, causing platform plate 201 to rise. The controller also controls the movable end of hydraulic cylinder 206 to extend, causing platform plate 201 to descend.

[0032] The slide movement mechanism 4 includes guide rails 401, racks 402, motors 403, a first slide 404, a second slide 405, and a third slide 406. The two guide rails 401 are adjustablely mounted on the base plate. Two relatively parallel first slides 404, two relatively parallel second slides 405, and two relatively parallel third slides 406 are sequentially slidably connected to the two guide rails 401. A rack 402 is provided on the inner wall of the guide rails 401. The motor 403 is fixedly connected to the top of each of the first slides 404, second slides 405, and third slides 406. The output shaft of the motor 403 is driven by a gear located at the bottom of each slide, meshing with the rack 402. Stewart platform assemblies 5 are connected to the first slides 404, second slides 405, and third slides 406.

[0033] Specifically, the motor 403 drives the gear to rotate. Because the gear meshes with the rack 402, the first slide 404, the second slide 405, and the third slide 406 can move along the guide rail 401. The distance between the first slide 404, the second slide 405, and the third slide 406 can be adjusted to accommodate test vehicles 7 with different wheelbases. By adjusting the distance between the two slide movement mechanisms 4 on the ground, it is possible to accommodate test vehicles 7 with different wheelbases.

[0034] The Stewart platform group 5 includes six six-DOF parallel robots. Each six-DOF parallel robot includes an upper platform 501, a lower platform 502, electric push rods 503, universal joints 504, and wheel limiting components 505. The lower platform 502 of each six-DOF parallel robot is fixedly connected to two first slides 404, two second slides 405, and two third slides 406, respectively. The top of the lower platform 502 is hinged to the fixed ends of the six electric push rods 503. The movable ends of the electric push rods 503 are connected to universal joints 504, which are connected to the bottom of the upper platform 501. The electric push rods 503 are equipped with load cells, tilt sensors, and displacement sensors.

[0035] Specifically, the lower platform 502 of the first six-DOF parallel robot is fixedly connected to one of the first slides 404, and the lower platform 502 of the second six-DOF parallel robot is fixedly connected to another first slide 404. The lower platform 502 of the third six-DOF parallel robot is fixedly connected to one of the second slides 405, and the lower platform 502 of the fourth six-DOF parallel robot is fixedly connected to another second slide 405. The lower platform 502 of the fifth six-DOF parallel robot is fixedly connected to one of the third slides 406, and the lower platform 502 of the sixth six-DOF parallel robot is fixedly connected to another third slide 406.

[0036] The wheel limiting assembly 505 includes U-shaped stops 5051, L-shaped ribs 5052, rubber anti-skid devices 5053, hanging rings 5054, and anti-slip cloth 5055. Two U-shaped stops 5051 are adjustable and symmetrically arranged on the top of the upper platform 501. Two L-shaped ribs 5052 are also adjustable and symmetrically arranged on the top of the upper platform 501. Rubber anti-skid devices 5053 are fixedly connected to the inner walls of both L-shaped ribs 5052. One side of the anti-rollover device 5053 is an arc-shaped surface, and the two U-shaped blocks 5051, the two L-shaped ribs 5052 and the two rubber anti-rollover devices 5053 form a space for placing the wheel 5056. The arc-shaped surface of the wheel 5056 contacts the arc-shaped surface of the rubber anti-rollover device 5053 to achieve front and rear limit of the wheel 5056. The two sides of the wheel 5056 contact the inner wall of the U-shaped blocks 5051 to achieve left and right limit of the wheel 5056.

[0037] Each of the two L-shaped ribs 5052 has a fixed hanging ring 5054 at its top. The upper platform 501 also has four fixed hanging rings 5054 at its top. Two of these hanging rings are located on one side of a U-shaped block 5051, and two more are located on the other side of the same block. These four hanging rings are used to wrap the binding rope around the vehicle body to prevent it from accidentally detaching from the Stewart platform assembly 5 during testing. The anti-slip cloth 5055 has hooks at both ends. Two hooks are attached to the hanging rings 5054 at the top of the L-shaped ribs 5052 to limit the wheel 5056 at the top of the wheel's curved surface, preventing the wheel from slipping and rolling during testing.

[0038] The upper platform 501 has multiple guide grooves 2 5057 and two guide grooves 3 5058. The extension lines of guide grooves 2 5057 and guide grooves 3 5058 are set perpendicularly. The bottom of the U-shaped stop 5051 has a through hole. The bolt 5059 passes through the U-shaped stop 5051 and guide groove 2 5057 and is connected with a nut. The bottom of the L-shaped rib 5052 also has a through hole. The bolt 5059 passes through the L-shaped rib 5052 and guide groove 3 5058 and is connected with a nut.

[0039] Specifically, the U-shaped stop 5051 moves along the second guide groove 5051 and is locked with bolt 5059, thus enabling the U-shaped stop 5051 to be adjustable. The L-shaped rib 5052 moves along the third guide groove 5058 and is locked with bolt 5059, thus enabling the L-shaped rib 5052 to be adjustable.

[0040] The rain shower mechanism 6 includes a frame 601, water supply pipes 602, a water supply pump 603, and spray heads 604. The frame 601 is a U-shaped frame 601. Multiple rows of water supply pipes 602 are provided on the top and sides of the U-shaped frame 601. Multiple spray heads 604 are evenly arranged in an array on the water supply pipes 602 to spray the top and sides of the vehicle. The water supply pump 603 is also connected to a water tank and is electrically connected to the controller.

[0041] A method for operating a vehicle testing platform based on a six-degree-of-freedom parallel robot includes the following steps: Step 1, the overall vehicle testing platform is in its initial state, with the Stewart platform group 5 located directly below the bottom of the fixed platform 3. When the vehicle under test 7 drives into the fixed platform 3, the slide movement mechanism 4 drives the two first slides 404 to move in a straight line parallel to the vehicle's driving direction, thereby moving the six-degree-of-freedom parallel robot on the two first slides 404 horizontally out from directly below the bottom of the fixed platform 3 and keeping it flush with the fixed platform 3, forming a vehicle testing plane that connects with the fixed platform 3.

[0042] Subsequently, the front axle wheels of the vehicle under test 7 drive onto the upper platform 501 of the two six-degree-of-freedom parallel robots, and the wheel limiting component 505 is operated to position and constrain the front axle wheels.

[0043] Repeat the above steps to drive the central axle wheels of the vehicle under test 7 onto the upper platforms 501 of the two six-DOF parallel robots on the second slide 405, and the rear axle wheels onto the upper platforms 501 of the two six-DOF parallel robots on the third slide 406. Operate the wheel limiting components 505 sequentially to perform wheel positioning and constraint. After completing the vehicle positioning and constraint procedures, perform the following tests: vehicle center of gravity measurement, vehicle rollover, vehicle vibration, vehicle road bump test, vehicle speed change driving test, vehicle collision test, and vehicle rain test.

[0044] Step 2: Conduct an independent vehicle climbing test using the slope adjustment mechanism 1 and the platform lifting mechanism 2.

[0045] Specifically, the operation method for vehicle positioning and constraint includes the following steps: Step 1, Disassembly Preparation: Remove the two L-shaped ribs 5052 and the two rubber anti-reverse devices 5053, loosen the bolts 5059 that fix the two U-shaped blocks 5051, so that the U-shaped blocks 5051 will move outward along the guide groove 5057 of the upper platform 501.

[0046] Step 2: Lateral positioning of the wheel. After the vehicle under test 7 drives onto the upper platform 501 of the Stewart platform group 5, move the two U-shaped blocks 5051 in the direction of the wheel sidewall so that the sides of the two U-shaped blocks 5051 are in close contact with the left and right sidewalls of the wheel. After confirming that the positioning is accurate, tighten the bolts 5059 of the two U-shaped blocks 5051 to achieve left and right limit of the wheel and prevent lateral slippage.

[0047] Step 3: Limit the front and rear of the wheel. Adjust the position of the two L-shaped ribs 5052 by moving them in the guide groove 3 5058 in the direction close to the wheel's arc surface, and push the first rubber anti-rollover device 5053 to tightly press against the front and rear ends of the wheel. Then, tighten the bolts 5059 of the L-shaped ribs 5052 to limit the front and rear of the wheel and prevent longitudinal movement.

[0048] Step four involves anti-slip treatment. The hooks on both sides of the anti-slip cloth 5055 are hooked into the hanging rings 5054 at the top of the two L-shaped ribs 5052, ensuring the anti-slip cloth 5055 covers the upper part of the tire, increasing friction and preventing the wheel from slipping and rolling during the test. Next, safety precautions are taken. The binding rope is threaded through the four hanging rings 5054 fixed around the upper platform 501 and wrapped around the chassis beam to prevent the vehicle from accidentally detaching from the platform during the test, providing additional safety protection. After completing vehicle positioning and constraint, the appropriate test mode is selected according to the test requirements, and the control system drives the Stewart platform assembly 5 to perform the corresponding movements for vehicle testing.

[0049] Step 5: After the test, perform a reset operation, remove the binding rope on the lifting ring 5054, remove the anti-slip cloth 5055, remove the two L-shaped ribs 5052 and the two rubber anti-reverse devices 5053, loosen the bolts 5059 of the two U-shaped blocks 5051, retract the Stewart platform assembly 5 to the fixed platform 3 and drive the vehicle away from the Stewart platform assembly 5. After the vehicle leaves the test platform system, control the slide moving mechanism 4 to drive the Stewart platform assembly 5 to move horizontally and retract to the bottom directly below the fixed platform 3.

[0050] Specifically, the working method of vehicle center of gravity measurement test is as follows: Figure 9 Down: Step 1: Perform vehicle positioning and constraint.

[0051] Step 2, Data Acquisition: The electric actuator 503 of Stewart platform assembly 5 is controlled to adjust the upper platform to a horizontal position, forming a horizontal test plane. Following the methods specified in GB / T12673-2019 "Methods for Measuring Main Dimensions of Automobiles" and GB / T12674—2024 "Methods for Measuring Mass Parameters of Automobiles, Trailers and Automobile Combinations", the wheelbase, wheel load, and overall vehicle mass are measured using load cells, position sensors, and tilt sensors. Specifically, the load cells, position sensors, and tilt sensors are all mounted on the electric actuator 503 of Stewart platform assembly 5.

[0052] Step 3: Calculate the horizontal centroid position. Based on the horizontal measurement data, calculate the distance of the centroid relative to the first axis: ; For the total mass of the vehicle. When it is horizontal, the first The load mass on the left side of the axle. When it is horizontal, the first The load mass on the right side of the axle. The distance between the centroid and the first axis. For the first The distance between the axis and the first axis.

[0053] Step four, calculate the distance between the center of mass and the vehicle's centerline using the following formula: ; This is the distance between the center of mass and the vehicle's centerline. For the first Wheelbase of the axle.

[0054] Step 5: Use the tilt test method to measure within the tilt angle range of 6° to 12° and collect data.

[0055] In the left-side tilting operation, the electric actuators 503 of the six-DOF parallel robot on the left side of Stewart platform group 5 simultaneously shorten and extend, driving the upper platform 501 to slowly tilt to the left around the vehicle's longitudinal axis, with a maximum upward speed not exceeding 3° / min. The tilt angle is recorded. Based on the wheel load data of each axle, the height of the left tilt center of gravity is calculated as follows: ; Right-side tilt condition: Control Stewart platform group 5 to move in the opposite direction and calculate the height of the right-side tilt center of gravity: ; Calculate the average of the two values ​​as the final centroid height: ; The tilt angle. tilt angle Time Normal load on the left wheel of the shaft tilt angle θ Time Right wheel normal load, The height of the center of gravity under left-side tilt conditions. The height of the center of gravity under right-side tilt conditions. Final center of gravity height. Record measurement data at at least five different tilt angles, calculate the center of gravity height of each set of data, and finally take the average value to obtain a more accurate center of gravity height.

[0056] Specifically, the working method of vehicle rollover testing is as follows: Figure 10 Down: Step 1: Perform vehicle positioning and constraint.

[0057] Step 2, Maximum Roll Stability Angle Test on the Left Side: Simultaneously shorten and extend the electric actuators 503 of the six-DOF parallel robot on the left side of Stewart platform group 5, driving the platform to slowly tilt to the left around the vehicle's longitudinal axis. The tilting rate of the upper platform 501 remains constant, with an upward speed not exceeding 3° / min and a downward speed not exceeding 27° / min. The roll angle is monitored in real time using a tilt sensor, and the load change on the right wheel is monitored using a load cell. Tilting stops when the normal reaction force on all right wheel support planes is zero. The roll angle at this point is the maximum roll stability angle when the vehicle tilts to the left; record this maximum roll angle value. Slowly lower the upper platform 501 of Stewart platform group 5 to restore its horizontal posture. Repeat the test at least three times.

[0058] Step 3, Right Maximum Tilt Stability Angle Test: Control the electric actuator 503 of the six-DOF parallel robot on the left side of Stewart platform group 5 to extend synchronously, and control the electric actuator 503 of the six-DOF parallel robot on the right side of Stewart platform group 5 to shorten synchronously, driving the platform to slowly tilt to the right, and repeat the above steps.

[0059] Step 4, Result Processing: Calculate the arithmetic mean of the three measurements for left and right tilt as the maximum roll stability angle of the vehicle when tilting left and right, and take the smaller value as the maximum roll stability angle of the vehicle.

[0060] Specifically, the working method of vehicle vibration testing is as follows: Figure 11 Down: Step 1: Perform vehicle positioning and constraint; Step two, sinusoidal vibration test: including two modes: fixed frequency and swept frequency. The fixed frequency test involves synchronously extending and retracting the electric actuators 503 of all Stewart platform groups 5 at the same frequency, phase, and amplitude to induce resonance at a specific frequency. The resonance response is monitored by an accelerometer. The swept frequency test involves continuously varying the frequency within the frequency band and sweep time. Displacement sensors are used to monitor amplitude changes, identify the vehicle's multiple natural frequencies, and analyze transmission characteristics.

[0061] Frequency sweep vibration: Controls all Stewart platform group 5 electric push rods 503 to maintain phase synchronization, so that the vibration frequency changes continuously at a constant rate within a preset range, systematically scanning the excitation frequency, which is used to identify the multi-order resonance frequency of the vehicle or to conduct vibration resistance tests on multiple independent samples at the same time.

[0062] Step 3, Random Composite Vibration Test: Random vibration signals are generated based on power spectral density (PSD) data collected from actual roads, driving each electric actuator 503 of all Stewart platform groups 5 to simulate broadband random road surface excitation. Simultaneously, through the coordinated motion of Stewart platform groups 5, multi-degree-of-freedom vibration simulations are achieved, including vertical (Z-axis), pitch (around the Y-axis), and roll (around the X-axis). During the test, triaxial accelerometers monitor the vehicle's vertical and lateral acceleration responses in real time. Half-sine wave displacement and angular displacement excitations can be superimposed on the random composite vibrations to reproduce impact conditions, comprehensively evaluating the vehicle's vibration response and impact resistance performance under complex dynamic environments. Specifically, the triaxial accelerometers are also mounted on the electric actuators 503 of Stewart platform group 5.

[0063] Step four: During the test, the vibration acquisition system includes an accelerometer, a displacement sensor, a data acquisition front-end, and a processing system. It can acquire vibration signals in real time, process sensor data through spectrum analysis, extract characteristic parameters such as frequency and amplitude, and calculate vertical and lateral stability indices, maximum acceleration and average acceleration, etc., to comprehensively evaluate the vehicle's vibration performance and structural durability.

[0064] Specifically, the working method of road bump test is as follows: Figure 12 Down: Step 1: Perform vehicle positioning and constraint; Step two, periodic bump simulation test, working condition one (unidirectional vibration): The six-DOF parallel robots on the left and right sides of Stewart platform group 5 extend and retract synchronously with the same frequency and amplitude to simulate the periodic bumps of a vehicle on a smooth road. The length of the electric push rod 503 is adjusted in real time using a displacement sensor.

[0065] Condition 2 (Reverse Vibration): The six-DOF parallel robots on the left and right sides of Stewart platform group 5 move in opposite phases. For example, when the electric push rod 503 on the left extends, the electric push rod 503 on the right shortens, simulating the alternating left-right bumping of a vehicle on a wavy road. The front axle platform group, i.e., the six-DOF parallel robot located on the first slide 404, moves in opposite phases to the six-DOF parallel robots on the middle and rear axle platform groups, i.e., the second slide 405 and the third slide 406. For example, when the electric push rod 503 on the front axle extends, the electric push rod 503 on the middle and rear axles shortens, simulating the alternating front-to-back bumping of a vehicle on a wavy road. The push rod length is adjusted in real time by displacement sensors.

[0066] Step 3, Random Bump Simulation Test: The actual collected road vibration power spectral density (PSD) data is input into the control system to generate a time-domain vibration signal. Stewart platform group 5 independently adjusts the length and frequency of the electric actuator 503 based on the PSD data to simulate random vibrations on different road surfaces. A six-dimensional force sensor monitors changes in wheel dynamic load and dynamically adjusts the vibration signal to match the target PSD. Specifically, the six-dimensional force sensor is also mounted on the electric actuator 503.

[0067] Specifically, the working method of the variable speed driving test is as follows: Figure 13 Down: Step 1: Perform vehicle positioning and constraint.

[0068] Step two, acceleration test: The sliding mechanism drives the first slide 404, the second slide 405, and the third slide 406, and moves the vehicle on the Stewart platform group 5 with an initial acceleration, causing the vehicle to be subjected to a backward inertial force. The acceleration is continuously increased to the target maximum value, and simultaneously the electric push rod 503 of the front axle platform group extends, while the electric push rod 503 of the middle and rear axle platform groups shortens, creating a pitch angle for the front of the vehicle.

[0069] Step 3: Deceleration test. The control slide movement mechanism drives the first slide 404, the second slide 405, and the third slide 406, causing the vehicle on the Stewart platform to accelerate in the opposite direction of travel, thus subjecting the vehicle to forward inertial force. Simultaneously, the electric push rod 503 of the front axle platform group shortens, while the electric push rod 503 of the middle and rear axle platform groups extends, creating a pitch angle for the front of the vehicle.

[0070] Specifically, the working method of vehicle crash testing is as follows: Figure 14 Down: First, vehicle positioning and constraint are performed.

[0071] Second, the acceleration phase: the control slide movement mechanism 4 drives the slide and drives the vehicle located on the Stewart platform group 5 to accelerate in the direction of travel, so that the vehicle and the Stewart platform group 5 can obtain a basic speed.

[0072] Third, attitude adjustment: The vehicle attitude is adjusted by Stewart platform group 5 to simulate the actual driving state before the collision. For example, the vehicle maintains horizontal movement in the event of a frontal collision, and the platform group on one side is controlled to be slightly higher than the other side in the event of an offset collision to simulate offset movement.

[0073] Step 4, Instantaneous Acceleration Compensation: After the slide accelerates to its maximum speed within its capacity, the electric push rod 503 of the Stewart platform group 5 is controlled to extend rapidly, applying an instantaneous compensation acceleration to the vehicle in the same direction as the slide's movement, so that the vehicle reaches the preset collision speed in a very short time.

[0074] Step 5, Collision Simulation: After reaching the preset speed, the slide movement mechanism 4 brakes urgently and controls the electric push rod of the Stewart platform group 5 to retract according to the preset deceleration curve, simulating energy absorption and vehicle deformation during the collision process.

[0075] Step Six, Data Acquisition and Analysis: The impact load on each wheel is monitored in real time using a six-dimensional force sensor, and the dynamic displacement of the platform and vehicle is recorded using displacement sensors. Acceleration, deceleration, and force data are collected to assess the vehicle's collision safety performance and structural crashworthiness.

[0076] Specifically, the working method for vehicle rain testing is as follows: Figure 15 Down: Step 1: Position and restrain the vehicle, and turn off the vehicle's headlights (both high and low beams), all four doors, hood, windows, and sunroof.

[0077] Step 2: The sliding platform moving mechanism 4 drives the sliding platform and moves the vehicle located on the Stewart platform group 5 to the rain shower mechanism 6. The water supply pump 603 is started to deliver pressurized water from the water supply pipeline 602 to each spray branch. The pressurized water is sprayed out from the array of spray heads 604 evenly distributed on each spray pipe to form a composite water curtain covering the top and sides of the vehicle body for rain intensity calibration.

[0078] Step 3, Rain Test: With the rain system continuously operating, the sliding mechanism 4 drives the slide to move the Stewart platform assembly 5 forward at a constant speed. The Stewart platform assembly 5 adjusts the vehicle's posture to simulate typical driving conditions, including combinations of forward tilt, backward tilt, and side tilt, allowing the vehicle under test to pass through the rain system at a constant speed. The vehicle passes through the entire spray area at a uniform speed while being sprayed. The test assesses the driver's field of vision (windshield wiper performance), records the external water flow pattern, evaluates the impact of side window spray on the rearview mirror's field of vision, and checks for any abnormal splashes or water seepage under dynamic conditions.

[0079] Step four: After the test, check and record the water leakage in enclosed spaces such as the cockpit and luggage compartment, the working status of the electrical system, and the sealing performance of specific areas such as door gaps, sunroof edges, and wiring harness interfaces.

[0080] Specifically, the working method of vehicle hill climbing test is as follows: Figure 16 Down: Step 1: Perform vehicle positioning and constraint.

[0081] Step 2, Test Platform Initialization: Operate hydraulic cylinder 102 to extend and retract synchronously, adjusting the ramp angle to the target slope angle. The road slope angle is fed back by a height sensor. Hydraulic cylinder 206 controls platform plate 201 to perform vertical lifting, creating a smooth transition surface with no height difference between the top of the ramp plate and platform plate 201 of the platform lifting mechanism 2, thus performing the corresponding vehicle climbing test. Specifically, the height sensor is located at the bottom of ramp plate 103.

[0082] Step 3, prescribed hill-climbing test: The vehicle starts from a straight section of road with the throttle fully open and drives up the designated slope to conduct the hill-climbing test. Data on vehicle speed and engine speed changes are collected. If the vehicle speed continues to increase or stabilizes during the hill-climbing process and can pass through the test section, the hill-climbing is considered successful, and the stable speed and maximum gradeability are recorded.

[0083] The relevant calculation formulas are as follows: The formula for calculating the dynamic factor is: ; As the driving force, For air resistance, The vehicle weight is expressed in Newtons (N). The dynamic factor directly reflects the vehicle's ability to overcome driving resistance (including rolling resistance, air resistance, slope resistance, and acceleration resistance), and can be expressed as... When testing climbing performance, the vehicle travels at a constant speed with zero acceleration. Therefore, the above formula can be simplified to . The rolling resistance coefficient, The longitudinal slope, The acceleration due to gravity is taken as 9.8 m / s². 2 Stable vehicle speed during constant-speed uphill climbing. It can be represented as: . , , These are all vehicle performance parameters.

[0084] slope With slope angle The conversion formula is The maximum power factor of the vehicle in first gear. for: ; Given the maximum climbing angle, the maximum climbing angle of the vehicle can be obtained from the above formula as: ; Step 4, Hill Start Test: After the vehicle reaches the midpoint of the hill, apply emergency braking, turn off the engine, let it stand still, restart it, and start the hill start test. Record the time taken to pass through the designated hill section and the final speed at the top of the hill.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A vehicle testing platform based on a six-degree-of-freedom parallel robot, characterized in that: The system includes a slope adjustment mechanism, a platform lifting mechanism, a fixed platform, a sliding table moving mechanism, a Stewart platform assembly, and a rain shower mechanism, all mounted on a base plate. The slope adjustment mechanism, platform lifting mechanism, and fixed platform are sequentially arranged on the base plate. The fixed platform has a hollow structure. The sliding table moving mechanism is positioned close to the fixed platform, with one end of the sliding table moving mechanism located within the fixed platform. The Stewart platform assembly is slidably connected to the sliding table moving mechanism and is initially located within the fixed platform. The rain shower mechanism is positioned above the other end of the sliding table moving mechanism, with its bottom fixed to the base plate. The Stewart platform assembly limits the movement of the wheels of the vehicle under test.

2. The vehicle testing platform based on a six-degree-of-freedom parallel robot according to claim 1, characterized in that: The slope adjustment mechanism includes a base, a hydraulic cylinder, and a ramp. The base is fixedly connected to the base plate. One end of the ramp is hinged to one end of the base. The other end of the base is hinged to the fixed end of the hydraulic cylinder. The movable end of the hydraulic cylinder is hinged to the bottom of the middle part of the ramp. The platform lifting mechanism includes a platform plate, two oppositely arranged scissor arms, a second base, a guide plate, a connecting shaft, and a second hydraulic cylinder. The second base is fixedly connected to the base plate. The scissor arms are diamond-shaped scissor arms, and the ends of the rods of the two diamond-shaped scissor arms are hinged together by the connecting shaft. One end of the bottom rod of each scissor arm is hinged to one side of the top of the base two. Two oppositely arranged guide plates are fixedly connected to the other side of the top of the base two. The guide plates are horizontally provided with guide grooves. The other ends of the bottom rods of the two scissor arms are respectively slidably connected in the two guide grooves. The bottom of the platform plate is also fixedly connected to two oppositely arranged guide plates. The guide plates are horizontally provided with guide grooves. One end of the top rod of each scissor arm is hinged to one side of the top of the platform plate, and the other end of the top rod of each scissor arm is slidably connected to the guide grooves at the bottom of the two platform plates. The guide plates at the bottom of the platform plate and the guide plates on the base are arranged vertically opposite to each other. The middle part of a connecting shaft at the bottom of the scissor arm is hinged to the fixed end of the second hydraulic cylinder, and the middle part of another connecting shaft at the bottom of the scissor arm is hinged to the movable end of the second hydraulic cylinder. The movable end of the second hydraulic cylinder is located between the guide plates on the base. Initially, the ramp plate is in contact with one side of the platform plate, and the platform plate is flush with the top of the fixed platform.

3. The vehicle testing platform based on a six-degree-of-freedom parallel robot according to claim 1, characterized in that: The sliding mechanism includes guide rails, a rack, a motor, a first slide, a second slide, and a third slide. Two guide rails are adjustablely mounted on the base plate. Two relatively parallel first slides, two relatively parallel second slides, and two relatively parallel third slides are sequentially slidably connected to the two guide rails. A rack is provided on the inner wall of each guide rail. A motor is fixedly connected to the top of each of the first, second, and third slides. The output shaft of the motor is driven by a gear located at the bottom of each of the first, second, and third slides, and the gear meshes with the rack for transmission. A Stewart platform assembly is connected to each of the first, second, and third slides.

4. The vehicle testing platform based on a six-degree-of-freedom parallel robot according to claim 3, characterized in that: The Stewart platform group includes six six-degree-of-freedom parallel robots. Each six-degree-of-freedom parallel robot includes an upper platform, a lower platform, electric push rods, universal joints, and wheel limiting components. The lower platform of each six-degree-of-freedom parallel robot is fixedly connected to two first slides, two second slides, and two third slides, respectively. The top of the lower platform is hinged to the fixed ends of the six electric push rods. The movable ends of the electric push rods are connected to universal joints, which are connected to the bottom of the upper platform. The electric push rods are equipped with load cells, tilt sensors, and displacement sensors. The wheel limiting assembly includes a U-shaped stop, an L-shaped rib, a rubber anti-rollover device, a hanging ring, and an anti-slip cloth. The two U-shaped stops are adjustable and symmetrically arranged on the top of the upper platform. The two L-shaped ribs are also adjustable and symmetrically arranged on the top of the upper platform. A rubber anti-rollover device is fixedly connected to the inner wall of each of the two L-shaped ribs. One side of the rubber anti-rollover device is an arc-shaped surface. The two U-shaped stops, the two L-shaped ribs, and the two rubber anti-rollover devices form a space for placing the wheel. The arc-shaped surface of the wheel contacts the arc-shaped surface of the rubber anti-rollover device, and the two sides of the wheel contact the inner wall of the U-shaped stop. Each of the two L-shaped ribs has a hanging ring fixedly connected to its top, and the top of the upper platform also has four hanging rings fixedly connected to its top. Two of the hanging rings are located on one side of a U-shaped block, and two of the hanging rings are located on one side of another U-shaped block. The four hanging rings are used to wrap the binding rope, which is used to bind the vehicle body. The anti-slip cloth has hooks at both ends, and two of the hooks are respectively hooked onto the hanging rings at the top of the L-shaped ribs to limit the wheel at the top of the arc surface of the wheel.

5. A vehicle testing platform based on a six-degree-of-freedom parallel robot according to claim 4, characterized in that: The upper platform is provided with multiple guide grooves 2 and two guide grooves 3. The extension lines of guide grooves 2 and 3 are set perpendicularly. The bottom of the U-shaped block is provided with a through hole. Bolts pass through the U-shaped block and guide groove 2 and are connected with nuts. The bottom of the L-shaped rib is also provided with a through hole. Bolts pass through the L-shaped rib and guide groove 3 and are connected with nuts.

6. A vehicle testing platform based on a six-degree-of-freedom parallel robot according to claim 1, characterized in that: The rain shower mechanism includes a frame, water supply pipes, a water pump, and spray heads. The frame is a U-shaped frame, and multiple rows of water supply pipes are provided on the top and sides of the U-shaped frame. Multiple spray heads are evenly arranged in an array on the water supply pipes to spray the top and sides of the vehicle. The water pump is also connected to a water tank and is electrically connected to a controller.

7. The working method of a vehicle testing platform based on a six-degree-of-freedom parallel robot as described in any one of claims 1-6, characterized in that: The process includes the following steps: Step 1, the overall vehicle test platform is in its initial state. The Stewart platform assembly is located directly below the bottom of the fixed platform. When the vehicle under test drives into the fixed platform, the sliding table moving mechanism drives the two first sliding tables to move in a straight line parallel to the vehicle's driving direction, thereby moving the six-degree-of-freedom parallel robots on the two first sliding tables horizontally out from directly below the bottom of the fixed platform and keeping them flush with the fixed platform to form a vehicle test plane that connects with the fixed platform. Subsequently, the front axle wheels of the vehicle under test were driven onto the upper platform of two six-degree-of-freedom parallel robots, and the wheel limiting components were operated to position and constrain the front axle wheels. Repeat the above steps to drive the central axle wheels of the vehicle under test onto the upper platforms of the two six-DOF parallel robots on the second slide, and the rear axle wheels onto the upper platforms of the two six-DOF parallel robots on the third slide. Operate the wheel limiting components to perform wheel positioning and constraint in sequence. After completing the vehicle positioning and constraint operation, perform the vehicle center of gravity measurement test, vehicle rollover test, vehicle vibration test, vehicle road bump test, vehicle speed change driving test, vehicle collision test, and vehicle rain test. Step two: Conduct an independent vehicle climbing test using the slope adjustment mechanism and platform lifting mechanism.

8. The working method of a vehicle testing platform based on a six-degree-of-freedom parallel robot according to claim 7, characterized in that: The vehicle center of gravity measurement test obtains the three-dimensional coordinates of the center of gravity by calculating the horizontal position of the vehicle's center of gravity, measuring the distance of the center of gravity relative to the vehicle's centerline, and measuring the height of the center of gravity using the tilt method. The vehicle rollover test is conducted by controlling the lateral movement of the Stewart platform assembly to create a rollover condition. The roll angle is monitored in real time by the tilt sensor and the load change of the right wheel is monitored by the load sensor. The tilting stops when the normal reaction force of the support plane of all the right wheels is zero. At this time, the roll angle of the platform is the maximum roll stability angle when the vehicle tilts to the left. The maximum roll angle value at this time is recorded. The vehicle vibration test includes sinusoidal vibration test and random composite vibration test; the extension and retraction motion of the Stewart platform group is used to simulate various test conditions and simulate the vibration excitation of actual complex road surfaces. The vehicle speed change driving test forms a pitch attitude by controlling the telescopic movement of the Stewart platform group, and generates forward and backward inertial forces by coordinating the linear acceleration and deceleration of the first slide, second slide, and third slide in the same direction, and performs acceleration and deceleration condition test. The vehicle collision test simulates the collision process through the coordinated movement of the sliding platform mechanism and the Stewart platform assembly. The sliding platform mechanism drives the Stewart platform assembly and accelerates the vehicle along the collision direction to a preset initial speed, adjusting the vehicle to a frontal or offset collision posture. Simultaneously, at the moment of collision, the electric push rod of the Stewart platform assembly is controlled to extend rapidly, applying an instantaneous compensating acceleration to the vehicle in the same direction of movement as the first, second, and third sliding platforms, so that the vehicle reaches the preset collision speed. Subsequently, the collision impact and energy absorption process are simulated by braking the first, second, and third sliding platforms and contracting the electric push rod of the Stewart platform assembly according to the deceleration curve. The vehicle rain test uses a coordinated spraying mechanism to simulate typical operating conditions of a vehicle in actual driving through the Stewart platform group, and monitors and records the sealing status of each part.

9. The working method of a vehicle testing platform based on a six-degree-of-freedom parallel robot according to claim 7, characterized in that: The vehicle climbing test uses hydraulic cylinder one of the slope adjustment mechanism to adjust the test slope of the ramp plate, and uses hydraulic cylinder two to control the lifting and lowering of the scissor arm to drive the platform plate and the fixed platform to form a continuous test plane, and performs the prescribed ramp vehicle climbing test and ramp start test.

10. The working method of a vehicle testing platform based on a six-degree-of-freedom parallel robot according to claim 7, characterized in that: The vehicle positioning and constraint operation method includes the following steps: Step 1, Disassembly Preparation: Remove the two L-shaped ribs and two rubber anti-reverse devices, loosen the bolts fixing the two U-shaped blocks, and let the U-shaped blocks move outward along the guide groove of the upper platform. Step 2: Lateral positioning of the wheel. After the vehicle under test drives onto the upper platform of the Stewart platform assembly, move the two U-shaped blocks in the direction of the wheel sidewall so that the sides of the two U-shaped blocks are in close contact with the left and right sidewalls of the wheel. After confirming that the positioning is accurate, tighten the bolts of the two U-shaped blocks to achieve left and right limit of the wheel and prevent lateral slippage. Step 3: Limit the front and rear of the wheel. Adjust the position of the two L-shaped ribs by moving them in the guide groove three in the direction close to the wheel's arc surface, and push the first rubber anti-rollover device to tightly press against the front and rear ends of the wheel. Then, tighten the bolts of the L-shaped ribs to limit the front and rear of the wheel and prevent longitudinal movement. Step four involves anti-slip treatment. Hooks on both sides of the anti-slip cloth are inserted into the hanging rings at the top of the two L-shaped ribs, ensuring the cloth covers the upper part of the tire to increase friction and prevent the wheel from slipping and rolling during the test. Next, safety precautions are taken. The binding rope is threaded through the four hanging rings fixed around the upper platform and wrapped around the chassis beam to prevent the vehicle from accidentally detaching from the platform during the test, providing additional safety protection. After vehicle positioning and constraint are completed, the appropriate test mode is selected according to the test requirements. The control system drives the Stewart platform assembly to perform the corresponding movements for vehicle testing. Step 5: After the test, perform a reset operation, remove the binding ropes on the lifting rings, remove the anti-slip cloth, remove the two L-shaped ribs and two rubber anti-slip devices, loosen the bolts of the two U-shaped blocks, retract the Stewart platform assembly to the fixed platform and drive the vehicle away from the Stewart platform assembly. After the vehicle leaves the test platform system, control the sliding mechanism to drive the Stewart platform assembly to move horizontally and retract it to the bottom directly below the fixed platform.

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