Inverted wheel-foot working condition detector

Abstract

The present application provides a kind of inverted wheel-foot working condition detector, including main frame, the front end of the main frame is equipped with electric control system and display, the rear end of the main frame is vertically slidingly connected with mobile detection device, the mobile detection device includes Y-axis moving device and X-axis moving device, the X-axis moving device and gripper type friction device are installed on the outer surface of the Y-axis moving device, and the gripper type friction device is clamped with the end of the X-axis moving device.It has the beneficial effects as follows, the present application is especially suitable for agricultural wheel-foot robot research and development and test, can simulate the friction characteristics and skidding behavior of wheel-foot under different field soil and road conditions, improve the traction efficiency, stability and operation reliability of wheel-foot in complex farmland environment, at the same time, the system test precision is high, repeatability is strong, operation is flexible, provides efficient and reliable technical means for agricultural wheel-foot chassis design and dynamics research.

Description

Technical Field

[0001] This invention is an inverted wheel and foot condition testing instrument, belonging to the technical field of tire and wheel and foot robot testing equipment. Background Technology

[0002] In the research of wheeled robots, electric wheel drive systems, and vehicle dynamics, the friction state between the tire and the ground directly affects whether the vehicle will slip. The grip capacity of a tire varies under different pressures, road materials, and disturbance conditions. If it is not possible to accurately determine when the tire begins to slip, it is difficult to maintain stable vehicle control. Therefore, establishing a testing device that can realistically simulate the stress conditions on a tire is of great significance.

[0003] Most common tire testing devices currently use a traditional clamping structure, where the tire is placed underneath and pressed down by an upper mechanism to generate normal pressure. A friction plate or drive mechanism then simulates the friction between the tire and the ground. While this method can perform basic testing, it has many problems in practical use.

[0004] First, in traditional structures, the weight of the wheel axle and the loading mechanism itself often directly participates in the normal force, making it difficult to control the actual applied pressure independently.

[0005] Specifically, in traditional test structures, the tire is typically mounted on a lower support platform, and normal pressure is generated by downward pressure from an upper loading mechanism. Since the axle, drive motor, and mounting bracket are all in the same force path as the tire, their own weight is directly transmitted to the tire contact surface through the axle. Therefore, the actual normal pressure between the tire and the ground is composed of both the external loading force and the structure's own weight, as shown in the following formula: ; In the formula, This indicates the normal pressure between the tire and the ground; This indicates the external pressure applied by the loading mechanism; and These represent the weights of the wheel axle, drive motor, and mounting structure, respectively.

[0006] Because these weights are difficult to adjust independently, the actual normal pressure acting on the tire is difficult to control precisely, especially under light load or low pressure conditions, where the test error is more obvious.

[0007] When simulating lower pressure or light load conditions, precise adjustment is often difficult. Secondly, the normal loading structure and friction adjustment structure are usually installed in the same system, and the forces in the two directions can affect each other, easily leading to unstable test results. Thirdly, at the moment the tire is about to slip, the existing structure lacks a clear mechanical trigger boundary, making it difficult to accurately determine the slip state and affecting the reliability and repeatability of the data.

[0008] Therefore, it is necessary to design a tire testing device with a more reasonable structure, so that the source of normal pressure is clear and controllable, the friction adjustment and loading processes are independent of each other, and the tire's slippage critical state can be judged more stably, thereby improving the testing accuracy and experimental reliability. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the purpose of this invention is to provide an inverted wheel foot condition testing instrument.

[0010] To achieve the above objectives, the present invention is implemented through the following technical solution: An inverted wheel foot condition testing instrument includes a main frame. The front end of the main frame is equipped with an electronic control system and a display. The rear end of the main frame is vertically slidably connected to a moving detection device. The moving detection device includes a Y-axis moving device and an X-axis moving device. The X-axis moving device and a gripper-type friction device are installed on the outer surface of the Y-axis moving device. The gripper-type friction device is clamped and connected to the end of the X-axis moving device.

[0011] Furthermore, the main frame includes an aluminum profile, the electronic control system is installed at the bottom front end of the aluminum profile, a work plate and a transparent partition are installed at the top front end of the aluminum profile and above the electronic control system, the display is placed on the work plate, and two Y-axis guide rails are symmetrically arranged at the rear end of the aluminum profile.

[0012] Furthermore, an angle iron is provided at the corner of the aluminum profile, and a bottom fixing plate is connected between the angle iron and the aluminum profile.

[0013] Furthermore, the Y-axis moving device includes a main board, and the corner of the main board is connected to the Y-axis moving slider through a fixed clamping device. The Y-axis moving slider is slidably connected to the Y-axis guide rail. A U-shaped groove is formed at the center of the outer surface of the main board. A cover plate is hinged to the top opening of the U-shaped groove through a movable hinge mechanism. The cover plate and the U-shaped groove form a closed space.

[0014] Furthermore, the X-axis moving device includes a mounting plate, which is fixedly installed inside the fixed suspension device. The top of the mounting plate is connected to the bottom of the Y-axis moving device. A laser displacement sensor is installed on the outer side surface of the mounting plate. A load-bearing angle iron is fixedly installed on the side plate of the fixed suspension device. The lower end of the fixed suspension device is fixed to the X-axis slider. The bottom of the X-axis slider is horizontally slidably connected to the X-axis guide rail. The X-axis guide rail is fixedly installed on the upper surface of the connecting plate. The connecting plate is fixedly installed on the upper part of the main friction plate. A limit plate is fixedly connected to the side of the connecting plate. A laser positioning column is fixedly installed on the top of the limit plate. The laser positioning column and the laser displacement sensor are arranged opposite each other in the horizontal direction. A side friction plate is fixedly installed on the side of the main friction plate.

[0015] Furthermore, the gripper-type friction device includes a housing, which is installed at the bottom of the main board. A drive motor and a sensor fixing plate are respectively fixed on the upper and lower sides inside the housing. A bidirectional threaded screw is connected between the sensor fixing plate and the output end of the drive motor. A slide is threaded onto the bidirectional threaded screw. The slide is slidably connected inside the housing. Sliding friction plates are installed on the opposite side of the slide and the sensor fixing plate. The two sliding friction plates are in frictional contact with the side friction plate. A triaxial force sensor is installed on the side of the sliding friction plate.

[0016] Furthermore, the two sets of the triaxial force sensors are respectively mounted on the slide and the sensor fixing plate.

[0017] Furthermore, the electronic control system includes a 24V power supply and a motor driver installed at the bottom front end of the aluminum profile. An analog-to-CAN communication transmitter and a Raspberry Pi 5 single-board computer are provided between the motor driver and the 24V power supply. A Raspberry Pi CAN communication module is provided on the side of the Raspberry Pi 5 single-board computer.

[0018] The beneficial effects of this invention are: This invention achieves precise adjustment of normal pressure by placing the tire upside down and applying load with an upper pressure plate, eliminating the need for traditional bottom support frames and lifting platforms. It features a compact structure and simple operation. Through a quickly replaceable friction plate and an independently adjustable gripper-type friction device, it enables rapid testing under different friction conditions and loads. Combined with a triaxial force sensor and a laser displacement sensor, it can directly measure friction force and slip displacement, achieving real-time monitoring of the wheel's slippage critical state under multiple working conditions.

[0019] This invention is particularly suitable for the research and testing of wheeled robots in agriculture. It can simulate the friction characteristics and slippage behavior of wheels under different field soil and road conditions, improving the traction efficiency, stability, and operational reliability of wheels in complex farmland environments. Simultaneously, the system offers high testing accuracy, strong repeatability, and flexible operation, providing an efficient and reliable technical means for the design and dynamics research of agricultural wheeled robot chassis.

[0020] This invention employs an inverted structural design, which effectively avoids the influence of the wheel and axle's own weight on the normal pressure.

[0021] This invention achieves continuously adjustable normal pressure through a motherboard fillable structure; achieves independent adjustment of tangential friction force through a gripper-type friction device; and achieves synchronous monitoring of force and displacement through a laser displacement sensor and a triaxial force sensor. This invention has strong repeatability and is applicable to tire slippage testing under different loads and friction materials. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments 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.

[0023] Figure 1 This is a schematic diagram of the structure of an inverted wheel foot condition testing instrument according to the present invention; Figure 2 This is a schematic diagram of the main frame structure of an inverted wheel foot condition testing instrument according to the present invention; Figure 3 This is a schematic diagram of the Y-axis moving device of an inverted wheel foot condition testing instrument according to the present invention; Figure 4 This is a schematic diagram of the X-axis moving device structure of an inverted wheel foot working condition detector according to the present invention; Figure 5 This is a schematic diagram of the gripper-type friction device structure of an inverted wheel foot condition testing instrument according to the present invention; Figure 6 This is a schematic diagram of the electrical control system structure of an inverted wheel foot condition testing instrument according to the present invention; Figure 7 This is a schematic diagram of the inverted wheel foot condition testing instrument of the present invention in its usage state. Figure 8 This is a flowchart illustrating the working condition testing process of an inverted wheel foot working condition testing instrument according to the present invention.

[0024] In the diagram, 1. Main frame; 11. Y-axis guide rail; 12. Aluminum profile; 13. Bottom fixing plate; 14. Angle iron; 15. Transparent partition; 16. Working plate; 2. Movement detection device; 21. Y-axis moving device; 211. Y-axis moving slider; 212. Main board; 213. Movable hinge mechanism; 214. Cover plate; 215. Fixed clamping device; 22. X-axis moving device; 221. Laser displacement sensor; 222. Hanging plate; 223. Load-bearing angle iron; 224. Laser positioning column; 225. Fixed suspension device; 226. X-axis slider 227. Side friction plate; 228. Connecting plate; 229. Main friction plate; 2210. Limiting plate; 2211. X-axis guide rail; 3. Grip-type friction device; 31. Drive motor; 32. Housing; 33. Slide table; 34. Bidirectional threaded screw; 35. Sensor fixing plate; 36. Sliding friction plate; 37. Triaxial force sensor; 4. Electrical control system; 41. 24V power supply; 42. Analog to CAN communication transmitter; 43. Motor driver; 44. Raspberry Pi 5 single-board computer; 45. Raspberry Pi CAN communication module; 5. Display. Detailed Implementation

[0025] 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.

[0026] Please see Figures 1-8 This invention provides a technical solution for an inverted wheel foot condition testing instrument, comprising a main frame 1, which is an inverted spatial structure with the upper part supporting the load and the lower part testing. The front end of the main frame 1 is equipped with an electronic control system 4 and a display 5. The rear end of the main frame 1 is vertically slidably connected to a moving detection device 2. The moving detection device 2 includes a Y-axis moving device 21 and an X-axis moving device 22. The X-axis moving device 22 and a gripper-type friction device 3 are mounted on the outer surface of the Y-axis moving device 21, and the gripper-type friction device 3 is clamped and connected to the end of the X-axis moving device 22. The moving detection device 2 is mounted above a Y-axis guide rail 11 and can be vertically adjusted along the Y-axis direction. The gripper-type friction device 3 is arranged in the lower area of ​​the moving detection device 2 to provide adjustable horizontal friction resistance during testing. The electronic control system 4 is electrically connected to the moving detection device 2, the gripper-type friction device 3, and each sensor to realize drive control and data acquisition.

[0027] See Figure 2The main frame 1 includes an aluminum profile 12. The electronic control system 4 is installed at the bottom front end of the aluminum profile 12. A work plate 16 and a transparent partition 15 are installed at the top front end of the aluminum profile 12 and above the electronic control system 4. The transparent partition 15 is used to safely isolate the working condition test area, the working condition control area, and the working condition display area. The display 5 is placed on the work plate 16. Two Y-axis guide rails 11 are symmetrically arranged at the rear end of the aluminum profile 12. The Y-axis guide rails 11 and the aluminum profile 12 form a spatial skeleton structure. Angle irons 14 are provided at the corners of the aluminum profile 12. The angle irons 14 improve the strength and stability of the aluminum profile 12. A bottom fixing plate 13 is connected between the aluminum profile 12 and the angle iron 14. The main frame 1 cleverly avoids the influence of the wheel axle's own weight on the normal pressure through the inverted structure, and forms a safe protection area. At the same time, it ensures the visibility of the test process. In addition, the spatial arrangement of the inverted structure of the main frame 1 allows the tire and drive system to be inverted during the test, so that the tire is upside down and comes into contact with the mobile detection device 2 from the bottom for easy testing. The mobile detection device 2 is pressed on the tire, and the normal pressure is determined only by the mass of the mobile detection device 2 and is not affected by the weight of the wheel axle itself, thereby realizing independent control of the normal loading.

[0028] See Figure 3 The Y-axis moving device 21 includes a main board 212. The corner of the main board 212 is connected to a Y-axis moving slider 211 via a fixing clamping device 215. The Y-axis moving slider 211 is slidably connected to the Y-axis guide rail 11. The Y-axis moving device 21, through the sliding cooperation between the Y-axis slider 211 and the Y-axis guide rail 11, allows the moving detection device 2 to be adjusted vertically to adapt to the installation height requirements of tires of different sizes. A U-shaped groove is formed at the center of the outer surface of the main board 212. A cover plate 214 is hinged to the top opening of the U-shaped groove via a movable hinge mechanism 213. The cover plate 214 can be opened within the range of motion limited by the movable hinge mechanism 213. The cover plate 214 and the... The U-shaped grooves form a closed space. During use, the overall mass can be changed by filling the U-shaped grooves with a medium, thereby continuously adjusting the normal pressure Fz and accurately simulating the tire contact state under different loads. In actual use, when the Y-axis moving device 21 needs to be adjusted downwards, it can move naturally downwards along the Y-axis guide rail 11 by the gravity generated by the main board 212 and its filling mass. When the position needs to be adjusted upwards, the operator can manually push the Y-axis moving device 21 upwards to slide it upwards along the Y-axis guide rail 11 to the required height. Since the device does not require frequent or precise dynamic height adjustment during testing, there is no need to configure an active drive mechanism such as a motor or lead screw, making the structure simpler and more reliable.

[0029] In addition, this device does not have a fixed limiting structure. The purpose of this is to facilitate the quick disassembly and modular assembly of the device, and to facilitate the replacement of test modules such as tires and friction plates. Therefore, the Y-axis moving device 21 adopts an open sliding structure design.

[0030] The formula for calculating the total mass of the mobile detection device 2 is as follows: ; In the formula, M represents the total mass of the mobile detection device 2. Indicates the mass of the medium filling the U-shaped groove; This indicates the inherent mass of the mobile detection device 2.

[0031] See Figure 4The X-axis moving device 22 includes a mounting plate 222, which is installed at the bottom of the Y-axis moving device 21. A laser displacement sensor 221 is installed on the outer side surface of the mounting plate 222. When in use, the laser displacement sensor 221 can detect the distance from its own position to the laser positioning post 224, thereby measuring the distance the main friction plate 229 moves under the push of the tire and determining the motion state and slip state during the tire driving process. The bottom of the mounting plate 222 is fixedly connected to the X-axis slider 226 through a fixed suspension device 225, which is used to support the mounting plate 222. The connection structure of the 22 and its upper detection components forms a limiting and supporting space for the hanging plate 222, thereby ensuring that the hanging plate 222 maintains structural stability during the movement of the Y-axis; the bottom position of the fixed suspension device 225 is equipped with the X-axis slider 226, which slides in cooperation with the X-axis guide rail 2211; at the same time, the side of the fixed suspension device 225 is also fixedly connected with a load-bearing angle iron 223, which is used to rigidly connect the fixed suspension device 225 to the main frame or the upper load-bearing structure to improve the load-bearing capacity and installation stability of the overall structure. The X-axis slider 226 is slidably connected to an X-axis guide rail 2211, which is mounted on a connecting plate 228. A limiting plate 2210 is connected to the side of the X-axis guide rail 2211. During use, after the tire contacts the main friction plate 229, the friction force generated between the tire and the main friction plate 229 pushes the main friction plate 229 to move along the X-axis guide rail 2211, causing the connecting plate 228 and the limiting plate 2210 to move together. A laser positioning post 224 is mounted on the top of the limiting plate 2210. The limiting plate 2210 and the connecting plate 228 are mounted on the main friction plate 229. The main friction plate 229 can be used to mount friction plates with different friction coefficients to simulate different road surface materials. A side friction plate 227 is provided on the side of the main friction plate 229. During use, the X-axis slider 226 is... The fixed mounting component remains stationary during testing. The X-axis guide rail 2211, which slides with it, is a movable component. When the tire contacts and rotates with the main friction plate 229, the frictional force generated between the tire and the main friction plate 229 acts on the main friction plate 229 and is transmitted to the X-axis guide rail 2211 through the connecting plate 228. This causes the X-axis guide rail 2211 to slide horizontally on the X-axis slider 226, making the main friction plate 229, the side friction plate 227, and the limiting plate 2210 move as a whole along the X-axis. When it moves to a preset position, the limiting plate 2210 will contact and collide with the fixed X-axis slider 226, thus forming a mechanical limiting structure. Under this limiting constraint, if the tire continues to rotate, relative slippage will occur between the tire and the main friction plate 229, thereby triggering a passive slippage state.

[0032] In use, the tire is mounted on the upper rear end of the main frame, and the test contact area is located between the bottom of the tire and the main friction plate 229. Since the axle, motor, and other drive mechanisms do not participate in this normal force path, the normal pressure generated by the tire on the main friction plate 229 is determined only by the total mass of the moving detection device 2. The formula for calculating the normal pressure is as follows: ; In the formula, Indicates normal pressure; This indicates the inherent mass of the mobile detection device 2; The mass of the medium filling the U-shaped groove is represented by g; g represents the acceleration due to gravity.

[0033] Specifically, this can be achieved by changing the filler quality. The normal pressure can be continuously adjusted. This allows for the construction of structures under different working conditions, including light, medium, and heavy loads. Because the normal force source is singular and the transmission path is clear, it avoids the errors caused by the self-overlapping of the drive system in traditional structures, achieving physical separation of the normal load and the drive system. This provides stable mechanical boundary conditions for subsequent independent adjustment of tangential friction and slippage determination.

[0034] Complete the normal pressure Once set, the tangential force relationship between the tire and the test contact surface is established. The test contact surface is provided by the X-axis moving device 22. The main friction plate 229 is mounted on the X-axis guide rail 2211 via the X-axis slider 226, enabling it to perform low-resistance linear motion in the horizontal direction.

[0035] A limiting plate 2210 is provided at the end of the main friction plate 229 away from the tire driving direction to limit the maximum displacement stroke of the main friction plate 229 and form a clear mechanical boundary condition. When the main friction plate 229 is not in contact with the limiting plate 2210, the system is in a free friction state; when the main friction plate 229 moves to the position of the limiting plate 2210, the system forms a rigid constraint boundary, providing a physical trigger condition for subsequent slippage determination.

[0036] The main friction plate 229 has a detachable structure, and different friction material layers can be fixedly installed on its surface to change the coefficient of friction μ between the tire and the main friction plate 229. Under normal pressure... Under the given conditions, the theoretical tangential friction force between the tire and the main friction plate 229 should satisfy the following formula: ; In the formula, denoted by μ, which represents the theoretical tangential frictional force between the tire and the main friction plate 229; μ represents the coefficient of friction between the tire and the main friction plate 229. Indicates normal pressure.

[0037] Based on the above formula for normal pressure, the formula for calculating the actual tangential friction force between the tire and the main friction plate 229 is as follows: ; In the formula, This represents the actual tangential frictional force between the tire and the main friction plate 229; μ represents the coefficient of friction between the tire and the main friction plate 229. This indicates the inherent mass of the mobile detection device 2; The mass of the medium filling the U-shaped groove is represented by g; g represents the acceleration due to gravity.

[0038] Therefore, the tangential friction force is simultaneously affected by the filling mass. The effect of friction coefficient μ; by changing the filler mass The normal load is adjustable, and the coefficient of friction μ can be adjusted by changing the surface material of the main friction plate 229.

[0039] like Figure 4 As shown, the X-axis moving device 22, through the X-axis slider 226 and the X-axis guide rail 2211, allows the main friction plate 229 to move freely in the horizontal direction. The main friction plate 229 has a detachable structure, allowing for the replacement of different friction materials as needed to simulate different road surface friction coefficients. After the tire is driven, it contacts the main friction plate 229 and, under the action of friction, pushes it towards the limiting plate 2210. When the main friction plate 229 moves to the position of the limiting plate 2210, a clear mechanical boundary is formed, thus constituting the passive slippage trigger condition, and the slippage state judgment is clear and reliable.

[0040] After the tire and the main friction plate 229 form a stable contact, the tire drive system starts and drives the tire to rotate. Due to the friction between the tire surface and the main friction plate 229, the tire will generate a tangential driving force on the main friction plate 229 when it rotates.

[0041] The test contact surface is provided by the X-axis moving device 22. The main friction plate 229 is mounted on the X-axis guide rail 2211 via the X-axis slider 226, enabling it to slide linearly with low resistance in the horizontal direction. When the tire drives to rotate, the friction between the tire surface and the main friction plate 229 will push the main friction plate 229 to move along the X-axis guide rail 2211, thereby forming a dynamic coupling relationship between the tire driving motion and the main friction plate motion.

[0042] A limiting plate 2210 is provided at the end of the main friction plate 229 away from the tire driving direction to limit the maximum travel of the main friction plate 229. When the main friction plate 229 is not in contact with the limiting plate 2210, the main friction plate is in a free-moving state; when the main friction plate moves to the position of the limiting plate 2210, the system forms a rigid mechanical boundary condition. The main friction plate 229 adopts a detachable structure, and its surface can be fitted with friction layers of different materials, such as rubber layers, sandpaper layers, or rough metal surfaces, to simulate the friction characteristics under different road conditions. By changing different friction materials, the adhesion conditions between the tire and the main friction plate can be changed, thereby realizing experimental simulation of different road conditions.

[0043] See Figure 5 The gripper-type friction device 3 includes a housing 32, which is installed at the bottom of the main board 212. A drive motor 31 and a sensor mounting plate 35 are respectively fixed to the upper and lower sides inside the housing 32. A bidirectional threaded screw 34 connects the sensor mounting plate 35 and the output end of the drive motor 31. A slide 33 is threaded onto the bidirectional threaded screw 34 and slidably connected inside the housing 32. Sliding friction plates 36 are installed on the opposite side of the slide 33 and the sensor mounting plate 35. The two sliding friction plates 36 rub against the side friction plate 227, thereby adjusting the friction force on the main friction plate 229. A triaxial force sensor 37 is installed on the side of the sliding friction plate 36, which can be used to simultaneously detect… The system measures normal pressure Fz, frictional force Fx, and lateral disturbance force Fy. Two sets of triaxial force sensors 37 are respectively mounted on the slide table 33 and the sensor fixing plate 35. When the sliding friction plate 36 contacts the side friction plate 227, the gripper-type friction device 3 changes the clamping force between them by adjusting the rotation of the bidirectional threaded screw 34, so that a pair of mutually canceling normal pressures are formed between the sliding friction plate 36 and the side friction plate 227, while the frictional force generated between the contact surfaces acts on the side friction plate 227. Since the side friction plate 227 and the main friction plate 229 are integrally connected, the frictional force is transmitted to the main friction plate 229, so that the main friction plate 229 is subject to adjustable sliding resistance when pushed by the tire. By changing the magnitude of the clamping force, the frictional resistance experienced by the tire under different ground adhesion conditions can be simulated, thereby realizing the detection of tire traction performance.

[0044] In use, the drive motor 31 rotates, causing the bidirectional threaded screw 34 to rotate. The screw pushes the slide 33 forward, causing the sliding friction plate 36 to contact the side friction plate 227 and generate an adjustable friction force. This friction force acts only in the X-axis direction, achieving independent adjustment of the tangential friction force, and does not participate in the normal loading path.

[0045] The formula for calculating the propulsion speed of the drive motor 31 is as follows: ; In the formula, This indicates the propulsion speed of slide 33; represents the angular velocity of the drive motor 31; p represents the lead of the bidirectional threaded screw 34.

[0046] In addition, the displacement calculation formula for the corresponding slide 33 is as follows: ; In the formula, This indicates the displacement of slide 33 along the X-axis at time t; t represents the time variable, and the unit is seconds (s). Indicates that slide 33 is at time 10:00. Instantaneous propulsion speed; This represents the integral variable, used to describe intermediate moments in the time history; Represents the time variable The derivative is used for integration operations.

[0047] When the slide table 33 pushes the sliding friction plate 36 into contact with the side friction plate 227, the clamping normal force The calculation formula is as follows: ; In the formula, This indicates the clamping normal force after the slide table 33 pushes the sliding friction plate 36 into contact with the side friction plate 227; This indicates the transmission efficiency of the bidirectional threaded screw 34; represents the output torque of the drive motor 31; p represents the lead of the bidirectional threaded screw 34.

[0048] Clamping normal force Under the action of the sliding friction plate 36 and the side friction plate 227, an additional tangential frictional resistance is generated. The calculation formula for the additional tangential frictional resistance is as follows: ; In the formula, This indicates additional tangential frictional resistance; This represents the coefficient of friction of the gripper friction pair; This indicates the clamping normal force after the slide table 33 pushes the sliding friction plate 36 into contact with the side friction plate 227.

[0049] Since the gripper-type friction loading device 3 only acts in the horizontal direction, its force path does not pass through the main board 212 and it does not participate in the tire normal loading circuit. Therefore, it will not change the normal pressure generated by the mass of the moving detection device 2. The formula for calculating the total tangential drag of the system is: ; In the formula, The total tangential resistance of the system is represented by μ; μ represents the change in the coefficient of friction μ between the tire and the main friction plate 229. Indicates normal pressure; This indicates additional tangential frictional resistance.

[0050] Based on the aforementioned formula for calculating normal pressure, the formula for calculating the complete tangential resistance model of the system is as follows: ; In the formula, The total tangential resistance of the system is represented by μ; μ represents the change in the coefficient of friction μ between the tire and the main friction plate 229. This indicates the inherent mass of the mobile detection device 2; The mass of the medium filling the U-shaped groove is represented by g; g represents the acceleration due to gravity. This represents the coefficient of friction of the gripper friction pair; This indicates the transmission efficiency of the bidirectional threaded screw 34; represents the output torque of the drive motor 31; p represents the lead of the bidirectional threaded screw 34.

[0051] Before the formal test, the gripper-type friction device 3 is first pre-balanced. The specific steps are as follows: the drive motor 31 is started, and the bidirectional threaded screw 34 drives the slide 33 to move forward slowly, so that the sliding friction plate 36 clamps with the side friction plate 227; at the same time, the normal force data of the upper and lower triaxial force sensors 37 are read; by finely adjusting the position of the screw, the normal force values ​​detected by the upper and lower sensors are made consistent, thereby forming an internal force balance state. At this time, the upper and lower pressures inside the gripper system cancel each other out, and no additional normal load is applied to the tire, ensuring that the normal force on the tire during the test comes only from the weight of the moving detection device 2 itself.

[0052] After pre-balancing is completed, the tire drive system is activated. The tires contact the main friction plate 229 and generate friction, causing the main friction plate 229 to move along the X-axis under the action of the tires. The laser displacement sensor 221 detects the change in distance between the main friction plate 229 and the laser positioning post 224 in real time, obtaining the displacement x(t) and its trend; the triaxial force sensor 37 simultaneously collects the normal pressure Fz, tangential friction force Fx, and lateral disturbance force Fy, realizing synchronous monitoring of force and displacement data.

[0053] After the drive motor 31 starts, it drives the bidirectional threaded screw 34 to rotate, and a threaded transmission pair is formed between the screw and the slide table 33. As the screw rotates, the slide table 33 moves forward in the horizontal direction, thereby pushing the sliding friction plate 36 closer to the side friction plate 227.

[0054] When the sliding friction plate 36 comes into contact with the side friction plate 227, a clamping pressure is formed between them. As the slide continues to move forward, the contact pressure between the sliding friction plate 36 and the side friction plate 227 gradually increases, thereby generating frictional resistance between them.

[0055] Since the sliding friction plate 36 and the main friction plate 229 are rigidly connected, the frictional resistance generated by the side friction plate 227 will be transmitted to the main friction plate 229 through the sliding friction plate, causing the main friction plate to be subjected to additional resistance during the movement.

[0056] By controlling the rotation of the drive motor 31, the clamping force between the sliding friction plate and the side friction plate can be adjusted, thereby changing the magnitude of the additional frictional resistance of the system. This additional frictional resistance only acts on the horizontal movement of the main friction plate and does not participate in the tire's normal loading path, therefore it does not change the contact pressure between the tire and the main friction plate.

[0057] During the testing process, two working conditions can be tested depending on the different wheel-foot drive methods: The process of detecting the critical slippage under closed-loop drive conditions is as follows: When the wheel drive system adopts closed-loop speed control, the tire maintains a constant speed. As the clamping force between the sliding friction plate 36 and the side friction plate 227 gradually increases, the friction between them continuously increases, thus causing the sliding resistance on the main friction plate 229 to continuously increase. Since the drive system attempts to maintain a constant tire speed, a greater static friction force is required between the tire and the main friction plate 229 to overcome this resistance. When the static friction force reaches its limit, the contact state between the tire and the main friction plate 229 abruptly changes from static friction to sliding friction, and the tire begins to slip relative to itself. This is the critical state of tire slippage. By measuring the normal pressure Fz and friction force Fx in real time using the triaxial force sensor 37 and combining this with the tire speed change, the critical friction force at which tire slippage occurs can be determined.

[0058] The process of detecting the maximum traction force under open-loop drive conditions is as follows: When the wheel drive system adopts open-loop control, the driving torque of the tire remains constant. As the clamping force between the sliding friction plate 36 and the side friction plate 227 gradually increases, the frictional resistance of the side friction plate 227 continuously increases and is transmitted to the main friction plate 229 through the integrated connection structure, causing the resistance of the main friction plate 229 to continuously increase. Under the action of this resistance, the speed at which the tire pushes the main friction plate 229 will gradually decrease. When the clamping force further increases, the frictional resistance of the main friction plate 229 eventually exceeds the traction force that the tire can provide. At this time, the movement speed of the tire and the main friction plate 229 gradually decreases until it stops. The displacement change of the main friction plate 229 is detected by the laser displacement sensor installed in the system. When the detected displacement change approaches zero, it indicates that the tire can no longer push the main friction plate 229. At this time, the friction force measured by the triaxial force sensor 37 is the maximum traction force of the tire under this condition.

[0059] Through the two testing methods described above, the gripper friction device 3 can simulate different ground adhesion conditions by adjusting the frictional resistance, realize the tire slippage threshold detection under closed-loop drive conditions and the maximum traction force test under open-loop drive conditions, thereby comprehensively evaluating the traction performance of the wheel drive system under different working conditions.

[0060] See Figure 6 The electronic control system 4 includes a 24V power supply 31 and a motor driver 43 installed at the bottom front end of the aluminum profile 12. An analog-to-CAN communication transmitter 42 and a Raspberry Pi 5 single-board computer 44 are provided between the motor driver 43 and the 24V power supply 41. A Raspberry Pi 5 single-board computer 44 has a Raspberry Pi CAN communication module 45 on its side. The 24V power supply 41 provides power to the motor driver 43 and the drive motor 31. The motor driver 43 controls the drive motor 31 to adjust the pressure between the sliding friction plate 36 and the side friction plate 227. The analog-to-CAN communication transmitter 42 converts the displacement data measured by the laser displacement sensor 221 from analog to CAN signal. The Raspberry Pi CAN communication module 45 receives the CAN signal transmitted by the analog-to-CAN communication transmitter 42. The Raspberry Pi 5 single-board computer 44 parses the data and performs corresponding analysis, acting as a host computer.

[0061] After all mechanical operating parameters are set, the electronic control system 4 is started. The Raspberry Pi 5 single-board computer 44, through the CAN communication module 45, forms a centralized CAN bus control network with the analog-to-CAN communication transmitter 42 and multiple motor drivers 43, realizing unified management of data acquisition and drive control. The display 5 is electrically connected to the Raspberry Pi 5 single-board computer 44 and is used to display the system operating status and test parameters in real time.

[0062] The laser displacement sensor 221 outputs an analog voltage signal, which is input to the analog-to-CAN communication transmitter 42. The transmitter converts the analog signal into a standard CAN data frame and sends it to the CAN communication module 45 via the CAN bus. The Raspberry Pi 5 single-board computer 44 receives the displacement data in real time and performs timestamp marking, buffering, and filtering.

[0063] Let the real-time displacement of the main friction plate 229 be x(t). The system obtains the following through numerical differentiation: ; In the formula, v(t) represents the instantaneous velocity of the main friction plate 229 at time t; dx represents the minute change of the displacement x of the main friction plate 229 with respect to time t; dt represents the minute change of time; and a(t) represents the instantaneous acceleration of the main friction plate 229 at time t. It represents the second derivative of displacement x with respect to time t, that is, the change in the rate of change of displacement; The second derivative of time is used to represent the time scale of acceleration.

[0064] Meanwhile, the triaxial force sensor 37 outputs tangential force in real time. Normal force and lateral disturbance forces All data is transmitted to the main control unit via the CAN bus for synchronous processing, ensuring that force-displacement data are calculated on the same time reference.

[0065] The overall dynamics calculation formula for the system is: ; In the formula, M represents the equivalent mass involved in the motion, including the total equivalent mass of the main friction plate 229 and its rigidly connected components; x represents the displacement of the main friction plate 229 along the X-axis. This indicates the acceleration of the main friction plate 229 along the X-axis. This indicates the driving force exerted by the tire on the main friction plate 229; This represents the total tangential resistance acting on the main friction plate 229.

[0066] In the above formula, The calculation formula is as follows: ; In the formula, This indicates the driving force exerted by the tire on the main friction plate 229; R represents the driving torque output from the tire to the axle; R represents the effective rolling radius of the tire.

[0067] By calculating the above physical quantities in real time, the system achieves dynamic monitoring and analysis of the entire tire drive response process.

[0068] After the mechanical structure adjustment is completed, the electronic control system 4 is started. The electronic control system 4 is mainly used to realize drive control, sensor data acquisition, and test process management.

[0069] In the electronic control system 4, the laser displacement sensor 221 is used to measure the position change of the main friction plate 229 in real time. When the tire drives the main friction plate 229 to move, the laser displacement sensor 221 continuously measures the distance between the main friction plate 229 and the laser positioning post 224, thereby obtaining the displacement of the main friction plate. The triaxial force sensor 37 is used to measure the force on the main friction plate 229 in real time during the test, including the horizontal traction force, the vertical normal pressure, and the possible lateral disturbance force. All sensor data are transmitted to the main control unit via the CAN bus for synchronous recording and processing.

[0070] When the displacement of the main friction plate 229 changes abruptly, the friction force Fx changes abnormally, or the main friction plate 229 contacts the limiting plate 2210, it can be determined that the tire has entered a critical slippage state. This determination method combines the dual conditions of mechanical boundary triggering and sensor data changes, making slippage judgment clearer and more stable.

[0071] Upon detecting slippage or triggering a limit alarm, the Raspberry Pi 5 single-board computer 44 immediately sends stop and reverse reset commands to the motor driver 43, causing the slide 33 and the main friction plate 229 to return to their initial positions, completing the closed-loop control of the test. All displacement signals, triaxial force data, and motor control signals are uniformly managed and stored through the CAN bus, enabling complete data recording and traceable analysis.

[0072] After the test is completed, the main friction plate material can be changed, the main board filling quality adjusted, or the gripper friction force readjusted as needed to proceed to the next set of working conditions test. Through the above structure, this invention can perform repeatable tests under different normal loads, different friction materials, and different tangential loading conditions. The working condition switching is simple, and the results are stable and reliable.

[0073] This invention achieves complete separation of normal loading and tangential friction adjustment through the combination of an inverted force-bearing structure and a gripper-type independent friction adjustment mechanism. The force path is clear, avoiding the problems of self-overlapping and force coupling in traditional structures, and significantly improving test accuracy and repeatability.

[0074] In summary, this invention achieves single-path control of normal load through an inverted loading structure, variable friction coefficient through material replacement of the main friction plate, and independent adjustment of tangential resistance through a gripper-type friction device. Furthermore, it combines a triaxial force sensor and a laser displacement sensor to construct a force-displacement synchronous monitoring model, forming a closed-loop testing system with independent control of three parameters: normal load, adhesion conditions, and active resistance. The system exhibits a clear force path, thorough variable decoupling, and high test repeatability, making it suitable for accurate simulation and dynamic analysis of tire slippage under different loads and adhesion conditions.

[0075] Although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An inverted wheel foot condition testing instrument, characterized in that, The main frame (1) is provided with an electronic control system (4) and a display (5) at the front end of the main frame (1). A motion detection device (2) is vertically slidably connected to the rear end of the main frame (1). The motion detection device (2) includes a Y-axis motion device (21) and an X-axis motion device (22). The X-axis motion device (22) and a gripper friction device (3) are installed on the outer surface of the Y-axis motion device (21). The gripper friction device (3) is clamped and connected to the end of the X-axis motion device (22).

2. The inverted wheel foot condition testing instrument according to claim 1, characterized in that, The main frame (1) includes an aluminum profile (12), the electronic control system (4) is installed at the bottom front end of the aluminum profile (12), a working plate (16) and a transparent partition (15) are installed at the top front end of the aluminum profile (12) and above the electronic control system (4), the display (5) is placed on the working plate (16), and two Y-axis guide rails (11) are symmetrically provided at the rear end of the aluminum profile (12).

3. The inverted wheel foot condition testing instrument according to claim 2, characterized in that, An angle iron (14) is provided at the corner of the aluminum profile (12), and a bottom fixing plate (13) is connected between the angle iron (14) and the aluminum profile (12).

4. The inverted wheel foot condition testing instrument according to claim 3, characterized in that, The Y-axis moving device (21) includes a main board (212). The corner of the main board (212) is connected to the Y-axis moving slider (211) through a fixed clamping device (215). The Y-axis moving slider (211) is slidably connected to the Y-axis guide rail (11). A U-shaped groove is provided at the center of the outer surface of the main board (212). A cover plate (214) is hinged to the top opening of the U-shaped groove through a movable hinge mechanism (213). The cover plate (214) and the U-shaped groove form a closed space.

5. The inverted wheel foot condition testing instrument according to claim 4, characterized in that, The X-axis moving device (22) includes a mounting plate (222), which is fixedly installed inside the fixed suspension device (225). The top of the mounting plate (222) is connected to the bottom of the Y-axis moving device (21). A laser displacement sensor (221) is installed on the outer side surface of the mounting plate (222). A load-bearing angle iron (223) is fixedly installed on the side plate of the fixed suspension device (225). The lower end of the fixed suspension device (225) is fixed on the X-axis slider (226). The bottom of the X-axis slider (226) is connected to the X-axis guide rail (225). 211) Horizontal sliding connection, the X-axis guide rail (2211) is fixedly installed on the upper surface of the connecting plate (228), the connecting plate (228) is fixedly installed on the upper part of the main friction plate (229), the side of the connecting plate (228) is fixedly connected to the limiting plate (2210), the top of the limiting plate (2210) is fixedly installed with a laser positioning column (224), the laser positioning column (224) and the laser displacement sensor (221) are arranged opposite to each other in the horizontal direction, and the side of the main friction plate (229) is fixedly provided with a side friction plate (227).

6. The inverted wheel foot condition testing instrument according to claim 5, characterized in that, The gripper-type friction device (3) includes a housing (32), which is installed at the bottom of the main board (212). A drive motor (31) and a sensor fixing plate (35) are fixed on the upper and lower sides inside the housing (32), respectively. A bidirectional threaded screw (34) is connected between the sensor fixing plate (35) and the output end of the drive motor (31). A slide (33) is threaded on the bidirectional threaded screw (34). The slide (33) is slidably connected inside the housing (32). A sliding friction plate (36) is installed on the opposite side of the slide (33) and the sensor fixing plate (35). The two sliding friction plates (36) are in frictional contact with the side friction plate (227). A triaxial force sensor (37) is installed on the side of the sliding friction plate (36).

7. The inverted wheel foot condition testing instrument according to claim 6, characterized in that, The two sets of triaxial force sensors (37) are respectively mounted on the slide (33) and the sensor fixing plate (35).

8. The inverted wheel foot condition testing instrument according to claim 7, characterized in that, The electronic control system (4) includes a 24V power supply (41) and a motor driver (43) installed at the bottom front end of the aluminum profile (12). An analog-to-CAN communication transmitter (42) and a Raspberry Pi 5 single-board computer (44) are provided between the motor driver (43) and the 24V power supply (41). A Raspberry Pi 5 single-board computer (44) is provided on the side of the Raspberry Pi CAN communication module (45).

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