System and method for measuring rolling friction coefficient of airplane wheel

Abstract

The invention discloses a system and a method for measuring the rolling friction coefficient of an airplane wheel. The system comprises a lifting unit, a load applying unit, a driving unit and a control unit, the control unit is used for controlling the lifting unit to drive an airplane wheel assembly to rise under a set test condition, and controlling the driving unit to drive a rotary table to idle at a set rotating speed after the airplane wheel assembly is separated from the rotary table to obtain a first torque value; the lifting unit is controlled to drive the airplane wheel assembly to descend to the rotary table and then release the airplane wheel assembly, and the load applying unit is controlled to apply a set load to the airplane wheel assembly, so that the total load of the airplane wheel meets a set test condition; the driving unit is controlled to drive the rotary table to rotate at the set rotating speed, the airplane wheel assembly rolls on the runway surface of the rotary table at the set rolling radius, and a second torque value is obtained; the wheel rolling friction coefficient is calculated based on the first torque value, the second torque value, the set radius of rotation, and the total load. According to the invention, the rolling friction coefficient of the airplane wheel can be accurately measured.

Description

Technical Field

[0001] The present invention belongs to the technical field of unmanned aerial vehicle wheels, and more specifically, relates to a system and method for measuring a rolling friction coefficient of a wheel. Background Art

[0002] The information disclosed in the background technology section of the present invention is only intended to deepen the understanding of the general background technology of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to those skilled in the art. Summary of the invention

[0003] The purpose of the present invention is to propose a wheel rolling friction coefficient measurement system and method, so as to solve the problems that the traditional method of measuring the wheel rolling friction coefficient is time-consuming, labor-intensive, and economically costly, cannot meet the research and development needs, has a large range of empirical values, and is not accurate enough, and can accurately measure the wheel rolling friction coefficient at different rolling speeds, different loads, different road surfaces, and different tire pressures, thereby reducing time, labor, and economic costs.

[0004] To achieve the above object, the present invention proposes a system and method for measuring the rolling friction coefficient of an aircraft wheel.

[0005] According to a first aspect of the present invention, a system for measuring a rolling friction coefficient of an aircraft wheel is provided, comprising:

[0006] A lifting unit, used to drive the wheel assembly to rise and fall;

[0007] a load applying unit, for applying a set load to the wheel assembly;

[0008] A driving unit, used for driving the turntable to rotate;

[0009] a control unit, configured to control the lifting unit to drive the wheel assembly to lift under set test conditions, and control the driving unit to drive the turntable to idle at a set speed after the wheel assembly is separated from the turntable, so as to obtain a first torque value;

[0010] Controlling the lifting unit to drive the wheel assembly down to the turntable and then releasing the wheel assembly, and controlling the load applying unit to apply a set load to the wheel assembly so that the total load of the wheels in the wheel assembly meets the set test conditions;

[0011] Controlling the driving unit to drive the turntable to rotate at a set speed, and the wheel assembly rolls on the runway surface of the turntable at a set rolling radius to obtain a second torque value;

[0012] A wheel rolling friction coefficient is calculated based on the first torque value, the second torque value, the set rotation radius, and the total load.

[0013] Optionally, the lifting unit includes:

[0014] A lifting execution module, electrically connected to the control unit, and used to drive the wheel assembly to lift and lower under the control of the control unit;

[0015] An electrically controlled permanent magnet is disposed below the lifting execution module, connected to the lifting execution module via a steel cable, and electrically connected to the control unit;

[0016] The electrically controlled permanent magnet is demagnetized after being energized, and generates magnetic force after being deenergized.

[0017] Optionally, the measurement system further comprises:

[0018] The lifting unit is arranged on the upper part of the bracket.

[0019] Optionally, the load applying unit comprises:

[0020] An electromagnetic loading module is arranged below the electrically controlled permanent magnet and is electrically connected to the control unit. When the electrically controlled permanent magnet is powered off, the electrically controlled permanent magnet is attracted to the electromagnetic loading module. When the electrically controlled permanent magnet is powered on, the electrically controlled permanent magnet is separated from the electromagnetic loading module.

[0021] A hoisting platform is arranged below the electromagnetic loading module and is fixedly connected to the electromagnetic loading module;

[0022] A plurality of slide rails, fixed on the upright posts of the bracket and slidably connected to the hoisting platform;

[0023] The adapter assembly is arranged below the hoisting platform and is fixedly connected to the hoisting platform. The adapter assembly is used to install the wheel assembly, and the wheel assembly is arranged above the turntable.

[0024] Optionally, the driving unit comprises:

[0025] A motor with a built-in torque sensor and a speed sensor, wherein the torque sensor and the speed sensor are used to measure the torque and the speed of the output drive shaft of the motor, and the motor, the torque sensor and the speed sensor are electrically connected to the control unit respectively;

[0026] The turntable drive shaft is arranged below the turntable, the turntable drive shaft is drivingly connected to the output drive shaft of the motor, the turntable drive shaft is fixedly connected to the turntable, and the turntable is driven to rotate by the turntable drive shaft.

[0027] Optionally, the measurement system further comprises:

[0028] A weight sensor, disposed below the electrically controlled permanent magnet, for measuring the total load of the wheel;

[0029] The displacement sensor is arranged below the hoisting platform and is used to measure the position of the hoisting platform.

[0030] Optionally, the control unit comprises:

[0031] A control module, an AI module, an AO module, a DO module, a first comparator and a second comparator;

[0032] The input end of the AI ​​module is electrically connected to the weight sensor, the displacement sensor, the speed sensor and the torque sensor respectively; the weight output end and the torque output end of the AI ​​module are electrically connected to the weight feedback input end and the torque feedback input end of the control module respectively; the speed output end of the AI ​​module is electrically connected to the speed feedback input end of the first comparator; and the position output end of the AI ​​module is electrically connected to the position feedback input end of the second comparator;

[0033] The speed input terminal of the first comparator is electrically connected to the speed output terminal of the control module, and the output terminal of the first comparator is electrically connected to the speed input terminal of the AO module;

[0034] The weight input end of the AO module is electrically connected to the weight output end of the control module, the weight output end of the AO module is electrically connected to the electromagnetic loading module, and the speed output end of the AO module is electrically connected to the motor;

[0035] The position input terminal of the second comparator is electrically connected to the position output terminal of the control module; the output terminal of the second comparator is electrically connected to the input terminal of the DO module;

[0036] The output end of the DO module is electrically connected to the lifting actuator and the electric-controlled permanent magnet respectively.

[0037] Optionally, the test conditions set include:

[0038] Different turntable runway surfaces, different wheel tire pressures and different wheel rolling radii;

[0039] Motor speed, determined based on the UAV’s taxiing speed;

[0040] The total wheel load is determined based on the landing gear ground support force.

[0041] Optionally, the calculation expression of the wheel rolling friction coefficient is:

[0042] μ=F h / G to ;

[0043] Among them, F h is the wheel heading load, Fh =T S / R,T S is the actual torque output by the motor, R is the rolling radius of the wheel, G to is the total load of the wheel, Gto=Gw+Gz+Gs+G E , G w is the weight of the wheel assembly, G z is the weight of the adapter assembly, Gs is the weight of the lifting platform, G E It is the applied load of the electromagnetic loading module.

[0044] According to a second aspect of the present invention, a method for measuring a rolling friction coefficient of an aircraft wheel is provided. The method is based on a system for measuring a rolling friction coefficient of an aircraft wheel according to any one of the first aspects, comprising:

[0045] Determine the test conditions to be set;

[0046] The wheel assembly is mounted on the load applying unit, and the lifting unit is controlled to drive the wheel assembly to lift up based on the set test conditions. After the wheel assembly is separated from the turntable, the driving unit is controlled to drive the turntable to idle at a set speed to obtain a first torque value;

[0047] Controlling the lifting unit to drive the wheel assembly down to the turntable and then releasing the wheel assembly, and controlling the load applying unit to apply a set load to the wheel assembly so that the total load of the wheels in the wheel assembly meets the set test conditions;

[0048] Controlling the driving unit to drive the turntable to rotate at a set speed, and the wheel assembly rolls on the runway surface of the turntable at a set rolling radius to obtain a second torque value;

[0049] A wheel rolling friction coefficient is calculated based on the first torque value, the second torque value, the set rotation radius, and the total load.

[0050] The beneficial effects of the present invention are as follows: the present invention drives the wheel assembly to rise and fall through the lifting unit, applies a set load to the wheel assembly through the load applying unit, and drives the turntable to rotate through the driving unit; the control unit controls the lifting unit to drive the wheel assembly to rise under set test conditions, and controls the driving unit to drive the turntable to idle at a set speed after the wheel assembly is separated from the turntable, so as to obtain a first torque value; the lifting unit is controlled to drive the wheel assembly to descend to the turntable and then release the wheel assembly, and the load applying unit is controlled to apply a set load to the wheel assembly, so that the total load of the wheel in the wheel assembly meets the set test conditions; the driving unit is controlled to drive the turntable to rotate at a set speed, and the wheel assembly rolls on the runway surface of the turntable with a set rolling radius to obtain a second torque value; the wheel rolling friction coefficient is calculated based on the first torque value, the second torque value, the set rotation radius and the total load; the wheel rolling friction coefficient of the wheel under different rolling speeds, different loads, different pavements and different tire pressures is accurately measured, thereby reducing time, manpower and economic costs.

[0051] The system of the present invention has other characteristics and advantages, which will be apparent from the drawings incorporated herein and the following detailed description, or will be described in detail in the drawings incorporated herein and the following detailed description, which together serve to explain the specific principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, in which like reference numerals generally represent like components.

[0053] Figure 1 A schematic diagram of a wheel rolling friction coefficient measurement system according to a first embodiment of the present invention is shown.

[0054] Figure 2 A schematic diagram showing a control flow of a system for measuring a wheel rolling friction coefficient according to a first embodiment of the present invention is shown.

[0055] Figure 3 A schematic diagram of a calculation process of a wheel rolling friction coefficient according to the first embodiment of the present invention is shown. DETAILED DESCRIPTION

[0056] The present invention will be described in more detail below with reference to the accompanying drawings. Although preferred embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0057] A wheel rolling friction coefficient measurement system according to the present invention comprises:

[0058] A lifting unit, used to drive the wheel assembly to rise and fall;

[0059] a load applying unit, for applying a set load to the wheel assembly;

[0060] A driving unit, used for driving the turntable to rotate;

[0061] A control unit, used for controlling the lifting unit to drive the wheel assembly to lift under set test conditions, and controlling the driving unit to drive the turntable to idle at a set speed after the wheel assembly is separated from the turntable, to obtain a first torque value;

[0062] Control the lifting unit to drive the wheel assembly down to the turntable and then release the wheel assembly, and control the load applying unit to apply a set load to the wheel assembly so that the total load of the wheels in the wheel assembly meets the set test conditions;

[0063] Control the driving unit to drive the turntable to rotate at a set speed, and the wheel assembly rolls on the runway surface of the turntable at a set rolling radius to obtain a second torque value;

[0064] The wheel rolling friction coefficient is calculated based on the first torque value, the second torque value, the set rotation radius, and the total load.

[0065] Specifically, in the no-load stage, the control unit first causes the lifting unit to drive the wheel assembly to rise, and the wheel assembly is separated from the turntable. Then the drive unit drives the turntable to idle at a set speed. At this time, the first torque value obtained is mainly the friction torque that the turntable itself needs to overcome for rotation and the loss torque of the motor itself. In the loading test stage, the lifting unit releases the wheel assembly after it drops to the turntable, and the load application unit starts to work and applies the set load to the wheel assembly until the total load of the wheel in the wheel assembly meets the set test conditions. Then the drive unit drives the turntable to rotate at a set speed again, and the wheel assembly rolls on the runway surface of the turntable with a set rolling radius to obtain a second torque value. This second torque value includes the torque of the turntable idling (the part corresponding to the first torque value), the rolling friction torque between the wheel and the turntable runway surface, and other additional friction torques caused by loading. Finally, the wheel rolling friction coefficient is calculated based on the first torque value, the second torque value, the set rotation radius and the total load. The present invention can realize accurate measurement of the rolling friction coefficient of the wheel under different rolling speeds, different loads, different pavement surfaces and different tire pressures, thereby reducing time, manpower and economic costs; the rolling condition of the wheel on the runway can be simulated in a laboratory environment, and the rolling friction coefficient of the wheel can be accurately measured by accurately controlling various test conditions (such as rotation speed, load, etc.), thereby providing reliable data basis for the design of wheels or tires, material selection and optimization of runway pavement materials and processes.

[0066] In one example, the lifting unit includes:

[0067] A lifting execution module is electrically connected to the control unit and is used to drive the wheel assembly to lift and lower under the control of the control unit;

[0068] The electric-controlled permanent magnet is arranged below the lifting execution module, connected to the lifting execution module through a steel cable, and electrically connected to the control unit;

[0069] The electrically controlled permanent magnet is demagnetized when powered on and generates magnetic force when powered off.

[0070] Specifically, the internal structure of the electrically controlled permanent magnet includes a permanent magnet and an electromagnetic coil. Under normal conditions, the permanent magnet generates a stable magnetic field to keep the magnet magnetic. When the magnetic state needs to be changed, the electromagnetic coil is fed with a current of a certain direction and magnitude, and the magnetic field generated is superimposed or offset with the magnetic field of the permanent magnet, thereby achieving control of the magnetism. For example, when the magnetic field generated by the current is opposite to the magnetic field of the permanent magnet and the intensity is sufficient, the magnetism of the magnet can be weakened or even eliminated; and when the magnetic field generated by the current is in the same direction as the magnetic field of the permanent magnet, the magnetism can be enhanced. Compared with traditional electromagnets, electrically controlled permanent magnets do not need to be continuously energized when maintaining the magnetic state, and only consume electrical energy when changing the magnetic state (such as demagnetizing or enhancing the magnetism). This greatly reduces energy consumption and reduces the cost of use. Since the magnetism can be quickly changed by electric control, it can be demagnetized in time in some emergency situations or equipment failures to prevent the danger caused by accidental adsorption. By using the cooperation of the electrically controlled permanent magnet and the lifting and lowering execution module, the lifting and fixing of the wheel assembly can be accurately controlled, which is convenient for testing and studying the performance of the wheel under various working conditions.

[0071] In one example, the measurement system further includes:

[0072] The bracket and the lifting unit are arranged on the upper part of the bracket.

[0073] In one example, the load applying unit includes:

[0074] The electromagnetic loading module is arranged below the electric-controlled permanent magnet and is electrically connected to the control unit. When the electric-controlled permanent magnet is powered off, the electric-controlled permanent magnet and the electromagnetic loading module are attracted. When the electric-controlled permanent magnet is powered on, the electric-controlled permanent magnet and the electromagnetic loading module are separated.

[0075] The hoisting platform is arranged below the electromagnetic loading module and is fixedly connected to the electromagnetic loading module;

[0076] A plurality of slide rails are fixed on the upright posts of the bracket and are slidably connected with the lifting platform;

[0077] The adapter assembly is arranged below the hoisting platform and is fixedly connected to the hoisting platform. The adapter assembly is used to install the wheel assembly, and the wheel assembly is arranged above the turntable.

[0078] In one example, the drive unit includes:

[0079] The motor has a built-in torque sensor and a speed sensor, the torque sensor and the speed sensor are used to measure the torque and speed of the output drive shaft of the motor, and the motor, the torque sensor and the speed sensor are electrically connected to the control unit respectively;

[0080] The turntable drive shaft is arranged below the turntable, the turntable drive shaft is drivingly connected to the output drive shaft of the motor, the turntable drive shaft is fixedly connected to the turntable, and the turntable is driven to rotate through the turntable drive shaft.

[0081] In one example, the measurement system further includes:

[0082] A weight sensor is arranged below the electric-controlled permanent magnet and is used to measure the total load on the wheel;

[0083] The displacement sensor is arranged below the lifting platform and is used to measure the position of the lifting platform.

[0084] In one example, the control unit includes:

[0085] A control module, an AI module, an AO module, a DO module, a first comparator and a second comparator;

[0086] The input end of the AI ​​module is electrically connected to the weight sensor, the displacement sensor, the speed sensor and the torque sensor respectively; the weight output end and the torque output end of the AI ​​module are electrically connected to the weight feedback input end and the torque feedback input end of the control module respectively; the speed output end of the AI ​​module is electrically connected to the speed feedback input end of the first comparator; and the position output end of the AI ​​module is electrically connected to the position feedback input end of the second comparator;

[0087] The speed input terminal of the first comparator is electrically connected to the speed output terminal of the control module, and the output terminal of the first comparator is electrically connected to the speed input terminal of the AO module;

[0088] The weight input terminal of the AO module is electrically connected to the weight output terminal of the control module, the weight output terminal of the AO module is electrically connected to the electromagnetic loading module, and the speed output terminal of the AO module is electrically connected to the motor;

[0089] The position input terminal of the second comparator is electrically connected to the position output terminal of the control module; the output terminal of the second comparator is electrically connected to the input terminal of the DO module;

[0090] The output ends of the DO module are electrically connected to the lifting actuator and the electric-controlled permanent magnet respectively.

[0091] Specifically, the AI ​​module (analog input module) is mainly used to convert the analog signals from the weight sensor, displacement sensor, speed sensor and torque sensor into digital signals so that the control module can process them. The function of the AO module (analog output module) is opposite to that of the AI ​​module. It converts the digital signal sent by the control module into an analog signal and outputs it to the electromagnetic loading module and the motor. The electromagnetic loading module and the motor control the size of the physical quantity according to the received analog signal. The DO module (digital output module) is used to convert the digital signal sent by the control module into a discrete switch signal and output it to the lifting actuator and the electric permanent magnet to realize the on-off control of the lifting actuator and the electric permanent magnet. The digital signal has only two states, usually represented by 0 and 1, corresponding to the on and off of the lifting actuator and the electric permanent magnet.

[0092] In one example, the set test conditions include:

[0093] Different turntable runway surfaces, different wheel tire pressures and different wheel rolling radii;

[0094] Motor speed, determined based on the UAV’s taxiing speed;

[0095] The total wheel load is determined based on the landing gear ground support force.

[0096] In one example, the wheel rolling friction coefficient is calculated as:

[0097] μ=F h / G to ;

[0098] Among them, F h is the wheel heading load, F h =T S / R,T S is the actual torque output by the motor, R is the rolling radius of the wheel, G to is the total load of the wheel, Gto=Gw+Gz+Gs+G E , G w is the weight of the wheel assembly, G z is the weight of the adapter assembly, Gs is the weight of the lifting platform, G E It is the applied load of the electromagnetic loading module.

[0099] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but is not intended to be limiting of the present invention. It should be noted that the embodiments and features in the embodiments of the present invention may be combined with each other without conflict.

[0100] Embodiment 1

[0101] like Figure 1As shown, this embodiment provides a wheel rolling friction coefficient measurement system, including:

[0102] Lifting actuator 1, electric-controlled permanent magnet 2, electromagnetic loading device 3, adapter 4, wheel assembly 5, turntable 6, transmission belt 7, motor 8, display and control processing workstation 9, weight sensor 10, guide rail 11, hanging basket 12, displacement sensor 13, bracket 14, turntable drive shaft 15, motor output drive shaft 16.

[0103] The lifting actuator 1 is fixed on the bracket 14, and one end is connected to the electric control permanent magnet 2 by a steel cable, wherein the electric control permanent magnet 2 is demagnetized when powered on and generates magnetic force when powered off; the lower end of the electric control permanent magnet 2 is connected to the weight sensor 10; the lower end of the weight sensor 10 is connected to the electromagnetic loading device 3; the electromagnetic loading device 3 is fixed on the hanging basket 12, wherein the electromagnetic loading device can apply a load by increasing the voltage value; the upper end of the displacement sensor 13 is connected to the hanging basket 12, and the lower end is connected to the fixed installation plane of the turntable 6, wherein The displacement sensor is a pull-wire displacement sensor; the lower end of the hanging basket 12 is connected to the adapter 4; the lower end of the adapter 4 is connected to the wheel assembly 5; the wheel assembly 5 rolls on the turntable 6; the turntable drive shaft 15 and the motor output drive shaft 16 are connected by a transmission belt 7; the motor 8 drives the turntable drive shaft 15 through the motor output drive shaft 16; the motor 8 is connected to the display and control processing workstation 9 by cables; the display and control processing workstation 9 is connected to the electromagnetic loading device 3, the lifting actuator 1, the motor 6, the displacement sensor 13, and the weight sensor 10 by cables.

[0104] Set the test conditions, turntable runway surface, wheel tire pressure and wheel rolling radius, determine the motor speed based on the UAV taxiing speed, and determine the total wheel load based on the landing gear ground support force; Figure 2 As shown, the display and control processing workstation 9 includes a motor speed comparison module, a position comparison module, a DO, AO module, an AI module and a display and control processing terminal. The display and control processing terminal outputs a motor speed instruction through the comparison module and the AO module to the motor 8, and the rotation of the turntable 6 is realized by the motor 8; the display and control processing terminal outputs a position instruction through the comparison module and the DO module to the lifting actuator 1 and the electric control permanent magnet 2 to realize the lifting of the hanging basket 12; the display and control processing terminal outputs a weight instruction through the AO module to the electromagnetic loading device 3 to realize the change of the wheel load weight; the weight sensor 10, the displacement sensor 13, the torque sensor, and the speed sensor feed back the measurement information to the AI ​​module, and the AI ​​module feeds back the weight information to the display and control processing terminal after processing, and feeds back the position information to the position comparison module for comparison with the position input instruction and then to the DO module to control the lifting actuator 1 to control the change of the hanging basket 12, and at the same time, the motor speed information is fed back to the motor speed comparison module for comparison with the motor input to the input instruction and then to the AO module to control the motor 8 to drive the output shaft for transmission.

[0105] The turntable 6 is a ring with an inner diameter R n , the outer diameter of the ring R w , the rolling radius R of the wheels on turntable 6 is R n <R<R w The wheel rolling radius R on the turntable 6 is determined according to the position of the wheel contacting the turntable 6 ring. The wheel rolling speed V w =n*i*2πR / 60, where n is the motor input speed and i is the reduction ratio. The input speed and reduction ratio of the motor 8 are determined according to the wheel rolling speed. The calculation expression of the wheel rolling friction coefficient is: μ = F h / G to ; Among them, F h is the wheel heading load, F h =T S / R,T S is the actual torque output by the motor, R is the rolling radius of the wheel, G to is the total load of the wheel, Gto=Gw+Gz+Gs+G E , G w is the weight of the wheel assembly, G z is the weight of the adapter assembly, Gs is the weight of the hanging basket, G E is the load applied by the electromagnetic loading device.

[0106] like Figure 3 As shown, the motor speed n is used as input to determine and select the appropriate G w , G E As the initial value, calculate the total weight of the wheel load G to , respectively record the motor output torque T when the turntable is idling at the same speed S1 and load turntable output torque T S2 , and finally the difference between the front and rear torques T S , calculate the driving force on the tire, compare it with the load on the tire, and calculate the wheel rolling friction coefficient.

[0107] The advantages of the wheel rolling friction coefficient measurement system are:

[0108] (1) The test equipment involves comprehensive, complete and high-precision measuring equipment such as drive mechanisms, actuators, input and output and processing equipment.

[0109] (2) The measurement system can realize electromagnetic control of wheel load weight.

[0110] (3) The test equipment and method can measure the wheel friction coefficient under different rolling speeds, different loads, different road surfaces, and different tire pressures.

[0111] (4) The test equipment and method solve the problem of calculating the rolling friction coefficient of the wheels during the taxiing simulation of solar-powered UAVs, which can greatly reduce time, manpower and economic costs.

[0112] Embodiment 2

[0113] This embodiment provides a method for measuring a wheel rolling friction coefficient, comprising:

[0114] Determine the turntable runway surface, tire pressure, and wheel rolling radius.

[0115] Determine the motor speed, wheel load and other parameters according to the UAV taxiing speed and the ground support force of the landing gear, install the wheel assembly to the adapter, power on, use the display and control processing workstation to raise the wheel assembly to a certain height, and save the weight sensor feedback value.

[0116] Input a preset speed to the motor so that the motor drives the turntable to idle for a certain period of time by relying on the transmission belt. After the motor feedback value stabilizes, save the torque feedback value.

[0117] Slowly release the wheel assembly to the turntable runway surface, disengage the electronically controlled permanent magnet, input the determined wheel load value into the display and control processing workstation, input the same predetermined speed as when the turntable is idling into the motor, so that the motor drives the turntable to rotate for a certain period of time with the transmission belt, and save the torque feedback value after the motor feedback value stabilizes.

[0118] Power off and prepare for the next test.

[0119] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A wheel rolling friction coefficient measurement system, characterized in that: include: A lifting unit, used to drive the wheel assembly to rise and fall; a load applying unit, for applying a set load to the wheel assembly; A driving unit, used for driving the turntable to rotate; a control unit, configured to control the lifting unit to drive the wheel assembly to lift under set test conditions, and control the driving unit to drive the turntable to idle at a set speed after the wheel assembly is separated from the turntable, so as to obtain a first torque value; Controlling the lifting unit to drive the wheel assembly down to the turntable and then releasing the wheel assembly, and controlling the load applying unit to apply a set load to the wheel assembly so that the total load of the wheels in the wheel assembly meets the set test conditions; Controlling the driving unit to drive the turntable to rotate at a set speed, and the wheel assembly rolls on the runway surface of the turntable at a set rolling radius to obtain a second torque value; A wheel rolling friction coefficient is calculated based on the first torque value, the second torque value, the set rotation radius, and the total load.

2. The wheel rolling friction coefficient measurement system according to claim 1, characterized in that: The lifting unit comprises: A lifting execution module, electrically connected to the control unit, and used to drive the wheel assembly to lift and lower under the control of the control unit; An electrically controlled permanent magnet is disposed below the lifting execution module, connected to the lifting execution module via a steel cable, and electrically connected to the control unit; The electrically controlled permanent magnet is demagnetized after being energized, and generates magnetic force after being deenergized.

3. The wheel rolling friction coefficient measurement system according to claim 2, characterized in that: The measuring system further comprises: The lifting unit is arranged on the upper part of the bracket.

4. The wheel rolling friction coefficient measurement system according to claim 3, characterized in that: The load applying unit comprises: An electromagnetic loading module is arranged below the electrically controlled permanent magnet and is electrically connected to the control unit. When the electrically controlled permanent magnet is powered off, the electrically controlled permanent magnet is attracted to the electromagnetic loading module. When the electrically controlled permanent magnet is powered on, the electrically controlled permanent magnet is separated from the electromagnetic loading module. A hoisting platform is arranged below the electromagnetic loading module and is fixedly connected to the electromagnetic loading module; A plurality of slide rails, fixed on the upright posts of the bracket and slidably connected to the hoisting platform; The adapter assembly is arranged below the hoisting platform and is fixedly connected to the hoisting platform. The adapter assembly is used to install the wheel assembly, and the wheel assembly is arranged above the turntable.

5. The wheel rolling friction coefficient measurement system according to claim 4, characterized in that: The driving unit comprises: A motor with a built-in torque sensor and a speed sensor, wherein the torque sensor and the speed sensor are used to measure the torque and the speed of the output drive shaft of the motor, and the motor, the torque sensor and the speed sensor are electrically connected to the control unit respectively; The turntable drive shaft is arranged below the turntable, the turntable drive shaft is drivingly connected to the output drive shaft of the motor, the turntable drive shaft is fixedly connected to the turntable, and the turntable is driven to rotate by the turntable drive shaft.

6. The wheel rolling friction coefficient measurement system according to claim 5, characterized in that: The measuring system further comprises: A weight sensor, disposed below the electrically controlled permanent magnet, for measuring the total load of the wheel; A displacement sensor is arranged below the hoisting platform and is used to measure the position of the hoisting platform.

7. The wheel rolling friction coefficient measurement system according to claim 6, characterized in that: The control unit comprises: A control module, an AI module, an AO module, a DO module, a first comparator and a second comparator; The input end of the AI ​​module is electrically connected to the weight sensor, the displacement sensor, the speed sensor and the torque sensor respectively; the weight output end and the torque output end of the AI ​​module are electrically connected to the weight feedback input end and the torque feedback input end of the control module respectively; the speed output end of the AI ​​module is electrically connected to the speed feedback input end of the first comparator; and the position output end of the AI ​​module is electrically connected to the position feedback input end of the second comparator; The speed input terminal of the first comparator is electrically connected to the speed output terminal of the control module, and the output terminal of the first comparator is electrically connected to the speed input terminal of the AO module; The weight input end of the AO module is electrically connected to the weight output end of the control module, the weight output end of the AO module is electrically connected to the electromagnetic loading module, and the speed output end of the AO module is electrically connected to the motor; The position input terminal of the second comparator is electrically connected to the position output terminal of the control module; the output terminal of the second comparator is electrically connected to the input terminal of the DO module; The output end of the DO module is electrically connected to the lifting actuator and the electric-controlled permanent magnet respectively.

8. The wheel rolling friction coefficient measurement system according to claim 1, characterized in that: The test conditions set include: Different turntable runway surfaces, different wheel tire pressures and different wheel rolling radii; Motor speed, determined based on the UAV’s taxiing speed; The total wheel load is determined based on the landing gear ground support force.

9. The wheel rolling friction coefficient measurement system according to claim 7, characterized in that: The calculation expression of the wheel rolling friction coefficient is: μ=F h / G to ; Among them, F h is the wheel heading load, F h =T S / R,T S is the actual torque output by the motor, R is the rolling radius of the wheel, G to is the total load of the wheel, Gto=Gw+Gz+Gs+G E , G w is the weight of the wheel assembly, G z is the weight of the adapter assembly, Gs is the weight of the lifting platform, G E It is the applied load of the electromagnetic loading module.

10. A method for measuring a rolling friction coefficient of an aircraft wheel, based on the system for measuring a rolling friction coefficient of an aircraft wheel according to any one of claims 1 to 9, characterized in that: include: Determine the test conditions to be set; The wheel assembly is mounted on the load applying unit, and the lifting unit is controlled to drive the wheel assembly to lift up based on the set test conditions. After the wheel assembly is separated from the turntable, the driving unit is controlled to drive the turntable to idle at a set speed to obtain a first torque value; Controlling the lifting unit to drive the wheel assembly down to the turntable and then releasing the wheel assembly, and controlling the load applying unit to apply a set load to the wheel assembly so that the total load of the wheels in the wheel assembly meets the set test conditions; Controlling the driving unit to drive the turntable to rotate at a set speed, and the wheel assembly rolls on the runway surface of the turntable at a set rolling radius to obtain a second torque value; A wheel rolling friction coefficient is calculated based on the first torque value, the second torque value, the set rotation radius, and the total load.

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