Aircraft nose wheel cornering loading device and control system therefor

Abstract

This invention relates to the field of aircraft nose wheel steering loading control and simulation modeling technology, and particularly to an aircraft nose wheel steering loading device and its control system. The device includes a state perception module that acquires signals from the tested nose landing gear and pressure signals from the oscillating hydraulic cylinder to generate a system state vector; a dynamic modeling module that generates boundary parameters and phase difference data based on the state vector; a disturbance observation module that estimates the nonlinear disturbance torque based on the boundary parameters; a feedforward compensation calculation module that generates a pressure feedforward compensation amount based on the disturbance torque and phase difference data; and a command reconstruction module that corrects the compensation amount based on the load signal and generates a control current signal to drive a hydraulic servo proportional valve. This invention effectively counteracts the flexibility hysteresis of the mechanical support structure and solves the problem of high-frequency oscillation and distortion of the loading torque.

Description

Technical Field

[0001] This invention relates to the field of aircraft nose wheel steering load control and simulation modeling technology, and in particular to an aircraft nose wheel steering load device and its control system. Background Technology

[0002] The nose wheel steering loading technology is a key area of ​​aviation ground simulation testing. Its core components include a swing hydraulic cylinder providing torque power, a synchronous screw jacking mechanism maintaining mechanical stability, and a torque sensor providing feedback signals. The swing hydraulic cylinder generates rotational torque through internal blades driven by hydraulic pressure, simulating the resistance of ground friction to nose wheel steering during actual takeoff and landing. The synchronous screw jacking mechanism uses a motor-driven threaded pair to raise the nose to a specific height, lifting the nose wheel off the ground and placing it in a deflectable, loaded state. The torque loading process relies on a closed-loop control system to adjust the actuator output in real time, reconstructing the force state of the landing gear on the runway by simulating the correspondence between the wheel's rotational angular displacement and the reverse load.

[0003] Existing aircraft nose wheel steering loading technology suffers from the following technical challenges: Specifically, in the full physical signal closed-loop verification of the nose landing gear steering system of large passenger aircraft and the simulation of runway taxiing correction algorithms, the synchronous lead screw lifting mechanism provides the landing gear with structural stiffness different from that of real ground support. When the swinging hydraulic cylinder performs high-frequency reciprocating follow-up loading at an extremely small deflection angle, the compressibility of the hydraulic fluid and the nonlinear damping characteristics at the mechanical connection produce an unexpected superposition, causing a deep coupling mismatch between the actuator dynamics and the flexible characteristics of the support components. For example, during the simulation of a passenger aircraft entering the high-speed taxiing runway correction phase, the flight control software outputs a weak and rapid correction signal to drive the nose wheel deflection. Because the support stiffness cannot compensate for the feedback delay of the transient pressure change inside the hydraulic cylinder in real time, the system will induce high-frequency alternating torque oscillation at the moment of command reversal. This causes the torque signal collected by the physical sensors to deviate from the theoretical preset model. After being fed back to the control closed loop, this causes the taxiing trajectory simulation data to be distorted, affecting the accuracy of the robustness verification of the correction algorithm. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an aircraft nose wheel turning loading device and its control system. This invention solves the technical problem that the nonlinear damping fluctuations during the follow-up process of the swing hydraulic cylinder are coupled with the stiffness of the synchronous screw support, resulting in high-frequency oscillation and distortion of the loading torque when simulating small-angle high-frequency correction.

[0005] To solve the above-mentioned technical problems, the specific contents of the present invention are as follows: In a first aspect, the present invention provides an aircraft nose wheel turning loading device, comprising a device body and a control device that establishes a communication connection with the device body, the control device controlling the device body; The main body of the equipment includes: a test bench fixture, a test landing gear, a measuring component, a swing hydraulic cylinder, a synchronous lead screw, a servo motor, and a hydraulic servo proportional valve; The control device includes: The state perception module receives the angular displacement signal of the front landing gear, the load signal of the front landing gear, and the pressure signal of the swing hydraulic cylinder collected by the measurement component. It performs calculations on the angular displacement signal, the load signal, and the pressure signal of the swing hydraulic cylinder to generate transient change data, and generates a system state vector based on the transient change data. The dynamic modeling module receives the system state vector, inputs the system state vector into the preset hydraulic dynamic equation to generate system stability boundary parameters, and generates phase difference data of mechanical and hydraulic responses between the synchronous screw and the swing hydraulic cylinder based on the system state vector. The disturbance observation module receives system stability boundary parameters and inputs them into a preset observation model to generate nonlinear disturbance torques. The feedforward compensation calculation module receives nonlinear disturbance torque and phase difference data of mechanical and hydraulic responses between the synchronous lead screw and the swing hydraulic cylinder. Based on the nonlinear disturbance torque and phase difference data of mechanical and hydraulic responses between the synchronous lead screw and the swing hydraulic cylinder, it performs energy compensation calculation to generate pressure feedforward compensation amount. The instruction reconfiguration module receives the pressure feedforward compensation amount and the load signal of the test landing gear. Based on the load signal of the test landing gear, it performs error approximation control calculation on the pressure feedforward compensation amount to generate a corrected pressure feedforward compensation amount. Based on the corrected pressure feedforward compensation amount, it generates a control current signal and transmits it to the hydraulic servo proportional valve. The hydraulic servo proportional valve receives a control current signal and adjusts the valve opening according to the control current signal. The valve opening controls the hydraulic oil entering the swing hydraulic cylinder to drive the swing hydraulic cylinder.

[0006] Furthermore, in the aircraft nose wheel turning loading device of the present invention, the state perception module is configured to: receive the angular displacement signal of the tested nose landing gear, the load signal of the tested nose landing gear, and the pressure signal of the swing hydraulic cylinder collected by the measurement component; filter the angular displacement signal, the load signal, and the pressure signal of the swing hydraulic cylinder to generate a first angular displacement signal, a first load signal, and a first pressure signal; perform differential operation on the first angular displacement signal to generate a transient angular velocity; and perform derivative operation on the first load signal to generate a torque. Extreme points; calculate the mechanical backlash of the threaded pair of the synchronous screw based on the extreme points of transient angular velocity and torque; perform differential operation on the first pressure signal to generate the transient pressure difference rate of change; calculate the oil equivalent bulk elastic modulus correction amount based on the transient pressure difference rate of change, and the mechanical backlash and the oil equivalent bulk elastic modulus correction amount constitute transient change data; synchronize and align the mechanical backlash and the oil equivalent bulk elastic modulus correction amount in the same time sequence, and generate the system state vector based on the aligned and combined mechanical backlash and oil equivalent bulk elastic modulus correction amount.

[0007] Furthermore, in the aircraft nose wheel turning loading device of the present invention, the dynamic modeling module is configured to: receive the system state vector; extract the oil equivalent bulk elastic modulus correction and mechanical backlash from the system state vector; input the oil equivalent bulk elastic modulus correction into a preset hydraulic dynamic equation to generate damping parameters; convert the mechanical backlash into a step compensation term; construct a mechanical-hydraulic coupling state matrix based on the damping parameters and the step compensation term; jointly solve the mechanical-hydraulic coupling state matrix to generate phase difference data of the mechanical and hydraulic responses between the synchronous lead screw and the swing hydraulic cylinder; extract instability boundary parameters from the mechanical-hydraulic coupling state matrix; and output the instability boundary parameters as system stability boundary parameters to the disturbance observation module.

[0008] Furthermore, in the aircraft nose wheel turning loading device of the present invention, the disturbance observation module is configured to: receive system stability boundary parameters output by the dynamic modeling module; convert the system stability boundary parameters into nonlinear weighting factors; input the nonlinear weighting factors into a preset observation model to generate a reconstructed state feedback gain matrix; input the system state vector into the reconstructed state feedback gain matrix to generate the running trajectory of the test nose landing gear in the state space; calculate the equilibrium divergence rate of the running trajectory deviating from the preset equilibrium state; perform multiplication and exponential operations on the equilibrium divergence rate, mechanical backlash, and oil equivalent bulk elastic modulus correction to generate a disturbance torque calculation value; and use the disturbance torque calculation value as a nonlinear disturbance torque and send it to the feedforward compensation calculation module.

[0009] Furthermore, in the aircraft nose wheel turning loading device of the present invention, the feedforward compensation calculation module is configured to: receive the nonlinear disturbance torque transmitted by the disturbance observation module, and the phase difference data of the mechanical and hydraulic responses between the synchronous lead screw and the swing hydraulic cylinder generated by the dynamic modeling module; perform integral calculation based on the phase difference data of the mechanical and hydraulic responses between the synchronous lead screw and the swing hydraulic cylinder and the nonlinear disturbance torque to perform energy compensation calculation and generate a fluid compression potential energy compensation amount; generate a feedforward compensation signal containing the fluid compression potential energy compensation amount based on the fluid compression potential energy compensation amount; convert the feedforward compensation signal into a pressure feedforward compensation amount; and output the pressure feedforward compensation amount to the command reconstruction module.

[0010] Furthermore, in the aircraft nose wheel turning loading device of the present invention, the command reconstruction module is configured to: use the first load signal generated by the state perception module as the load signal of the tested nose landing gear; receive the first load signal and the pressure feedforward compensation amount output by the feedforward compensation calculation module; perform state space mapping operation on the first load signal to generate load trajectory discrete points; generate an ideal reference trajectory according to the preset nose wheel taxiing dynamics model; calculate the shortest mapping path from the load trajectory discrete points to the ideal reference trajectory; perform coordinate convergence operation on the pressure feedforward compensation amount along the direction of the shortest mapping path to perform error approximation control operation and generate a corrected pressure feedforward compensation amount; generate a control current signal according to the corrected pressure feedforward compensation amount and transmit it to the hydraulic servo proportional valve.

[0011] Furthermore, the aircraft nose wheel turning loading device of the present invention includes a measurement component comprising a two-component force measurement unit and an angle measurement unit; the two-component force measurement unit is mounted on the tested nose landing gear; the angle measurement unit is mounted on the rotation axis of the tested nose landing gear; the two-component force measurement unit collects the load signal of the tested nose landing gear and sends it to the state perception module; the angle measurement unit collects the angular displacement signal of the tested nose landing gear and sends it to the state perception module; a pressure measurement unit is configured inside the two chambers of the swing hydraulic cylinder; the pressure measurement unit collects the pressure signal of the swing hydraulic cylinder and sends it to the state perception module.

[0012] Furthermore, in the aircraft nose wheel turning loading device of the present invention, a servo motor is connected to a synchronous lead screw in the main body of the device; the synchronous lead screw is connected to the front landing gear under test; a displacement measuring unit is arranged on the side of the synchronous lead screw; the displacement measuring unit collects the lifting stroke data and feeds the lifting stroke data back to the control device; the control device receives the lifting stroke data and generates a speed adjustment command based on the lifting stroke data and sends it to the servo motor; the servo motor adjusts the motor speed according to the speed adjustment command.

[0013] Furthermore, in the aircraft nose wheel turning loading device of the present invention, the hydraulic servo proportional valve receives a control current signal; the hydraulic servo proportional valve adjusts the valve opening according to the control current signal; the valve opening adjusts the pressure inside the swing hydraulic cylinder by controlling the hydraulic oil entering the swing hydraulic cylinder; the pressure inside the swing hydraulic cylinder drives the swing hydraulic cylinder to output a turning torque.

[0014] Secondly, the present invention provides an aircraft nose wheel steering loading system, applied to an aircraft nose wheel steering loading device as described above, comprising: The state perception module receives the angular displacement signal of the front landing gear, the load signal of the front landing gear, and the pressure signal of the swing hydraulic cylinder collected by the measurement component. It performs calculations on the angular displacement signal, the load signal, and the pressure signal of the swing hydraulic cylinder to generate transient change data, and generates a system state vector based on the transient change data. The dynamic modeling module receives the system state vector, inputs the system state vector into the preset hydraulic dynamic equation to generate system stability boundary parameters, and generates phase difference data of mechanical and hydraulic responses between the synchronous screw and the swing hydraulic cylinder based on the system state vector. The disturbance observation module receives system stability boundary parameters and inputs them into a preset observation model to generate nonlinear disturbance torques. The feedforward compensation calculation module receives nonlinear disturbance torque and phase difference data of mechanical and hydraulic responses between the synchronous lead screw and the swing hydraulic cylinder. Based on the nonlinear disturbance torque and phase difference data of mechanical and hydraulic responses between the synchronous lead screw and the swing hydraulic cylinder, it performs energy compensation calculation to generate pressure feedforward compensation amount. The instruction reconfiguration module receives the pressure feedforward compensation amount and the load signal of the test landing gear. Based on the load signal of the test landing gear, it performs error approximation control calculation on the pressure feedforward compensation amount to generate a corrected pressure feedforward compensation amount. Based on the corrected pressure feedforward compensation amount, it generates a control current signal and transmits it to the hydraulic servo proportional valve. The hydraulic servo proportional valve receives a control current signal and adjusts the valve opening according to the control current signal. The valve opening controls the hydraulic oil entering the swing hydraulic cylinder to drive the swing hydraulic cylinder.

[0015] Beneficial effects of this invention: This invention uses a state-sensing module to collect real-time angular displacement signals, load signals, and pressure signals from the landing gear and the swing hydraulic cylinder before testing. It then performs calculations on these signals to generate transient change data and a system state vector. This invention accurately quantifies the degree of interference coupling between the synchronous lead screw support stiffness and the damping fluctuations of the swing hydraulic cylinder using the system state vector.

[0016] This invention utilizes a dynamic modeling module and a disturbance observation module to extract system stability boundary parameters and estimate nonlinear disturbance torque. A feedforward compensation calculation module combines phase difference data with the nonlinear disturbance torque to perform energy compensation calculations, thereby generating a pressure feedforward compensation amount. This invention pre-calculates and compensates for fluid compression losses before instability occurs due to synchronous screw backlash, overcoming the deficiency in traditional closed-loop control where support stiffness cannot compensate for pressure transient feedback delays in real time.

[0017] This invention utilizes an instruction reconstruction module to perform error approximation control calculations on the pressure feedforward compensation amount based on the load signal, generating a corrected pressure feedforward compensation amount and control current signal. A hydraulic servo proportional valve adjusts its valve opening according to the control current signal, pre-controlling the flow rate and direction of the hydraulic oil entering the swing hydraulic cylinder. This invention leverages pre-established hydraulic oil pressure to counteract the flexibility hysteresis of the mechanical support structure, completely solving the technical problem of high-frequency oscillation and distortion of the applied torque during simulated small-angle high-frequency correction, and significantly improving the accuracy of test data for passenger aircraft runway taxiing correction algorithms. Attached Figure Description

[0018] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0019] Figure 1 This is a system architecture diagram of an aircraft nose wheel steering loading control system according to the present invention. Detailed Implementation

[0020] To make the technical solution of the present invention clearer, the present invention will be clearly and completely described below with reference to specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. 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. The present invention provided by various embodiments will be described in detail below with reference to the accompanying drawings. To better understand the purpose of the present invention, the present invention will be described in further detail below.

[0021] Please see Figure 1 This invention proposes an aircraft nose wheel turning loading device, comprising a main body and a control device communicating with the main body; the control device controls the operation of the main body. The main body includes a test bench fixture, a test nose landing gear, a measuring component, a swing hydraulic cylinder, a synchronous lead screw, a servo motor, and a hydraulic servo proportional valve. The test bench fixture serves as the basic load-bearing structure, fixing the test nose landing gear and the swing hydraulic cylinder.

[0022] The following provides a detailed structural description of the main body of the equipment. The servo motor is an AC permanent magnet synchronous servo motor connected to a synchronous lead screw. The synchronous lead screw uses a precision ball screw transmission mechanism and is connected to the test front landing gear, adjusting the ground clearance of the test front landing gear through lifting motion. A displacement measurement unit, such as a linear displacement sensor, is configured on the side of the synchronous lead screw. The displacement measurement unit collects lifting stroke data and feeds it back to the control device; the control device receives the lifting stroke data and generates a speed adjustment command based on the lifting stroke data, sending it to the servo motor; the servo motor adjusts its speed according to the speed adjustment command to maintain a precise and stable support height.

[0023] The measurement components include a two-component force measurement unit and an angle measurement unit. The two-component force measurement unit uses a resistance strain gauge type two-dimensional force sensor, mounted on the front landing gear of the test vehicle, to collect the load signal of the front landing gear and send it to the status sensing module. The angle measurement unit uses a high-precision photoelectric encoder, mounted on the rotation axis of the front landing gear of the test vehicle, to collect the angular displacement signal of the front landing gear and send it to the status sensing module. A pressure measurement unit is configured inside the cavity of the swing hydraulic cylinder. The pressure measurement unit uses a piezoresistive pressure transmitter to collect the pressure signal of the swing hydraulic cylinder and send it to the status sensing module. The hydraulic servo proportional valve receives the control current signal and adjusts the valve opening according to the control current signal; the valve opening controls the flow rate and direction of the hydraulic oil entering the swing hydraulic cylinder, thus adjusting the pressure inside the swing hydraulic cylinder cavity; the pressure inside the swing hydraulic cylinder cavity drives the blades of the swing hydraulic cylinder to rotate, thereby outputting a turning torque.

[0024] The control device includes a state perception module, a dynamics modeling module, a disturbance observation module, a feedforward compensation calculation module, and a command reconstructing module. The state perception module receives angular displacement signals and load signals from the test landing gear, as well as pressure signals from the oscillating hydraulic cylinder, collected by the measurement components. It then performs calculations on the angular displacement, load, and pressure signals to generate transient change data and generates a system state vector based on this data. The dynamics modeling module receives the system state vector, inputs it into preset hydraulic dynamics equations to generate system stability boundary parameters, and simultaneously generates phase difference data between the mechanical and hydraulic responses of the synchronous lead screw and the oscillating hydraulic cylinder based on the system state vector.

[0025] The disturbance observation module receives system stability boundary parameters and inputs them into a preset observation model to generate nonlinear disturbance torques. The feedforward compensation calculation module receives the nonlinear disturbance torques and phase difference data, performs energy compensation calculations based on these data, and generates a pressure feedforward compensation quantity. The command reconstruction module receives the pressure feedforward compensation quantity and the load signal from the test landing gear, performs error approximation control calculations on the pressure feedforward compensation quantity based on the load signal, generates a corrected pressure feedforward compensation quantity, and generates a control current signal based on the corrected pressure feedforward compensation quantity, which is then transmitted to the hydraulic servo proportional valve.

[0026] The state perception module receives the angular displacement signal, load signal, and pressure signal of the front landing gear from the measurement component, as well as the pressure signal of the swing hydraulic cylinder. It then performs filtering to generate a first angular displacement signal, a first load signal, and a first pressure signal. A Butterworth low-pass filter is used to remove high-frequency electromagnetic interference noise during sensor signal transmission. Next, the first angular displacement signal is differentiated to generate a transient angular velocity. The first load signal is differentiated to generate torque extrema; these extrema are extracted by identifying the position where the first derivative of the load crosses zero and the sign of the second derivative changes. The state perception module calculates the mechanical backlash of the synchronous lead screw thread pair based on the transient angular velocity and torque extrema. The calculation process includes extracting the time interval between two adjacent torque extrema in opposite directions, integrating the transient angular velocity within that time interval to obtain the corresponding angle difference, and multiplying the angle difference by the lead screw lead parameter to convert it into mechanical backlash.

[0027] The first pressure signal is differentiated to generate a transient pressure difference rate of change. Based on this rate, the correction for the equivalent bulk elastic modulus of the oil is calculated. The calculation process uses an empirical formula for fluid compressibility, substituting the current ambient temperature parameter and the transient pressure difference rate of change into the formula to solve for the dynamically fluctuating correction for the equivalent bulk elastic modulus of the oil. The mechanical backlash and the correction for the equivalent bulk elastic modulus of the oil constitute transient change data. The state perception module synchronously aligns and combines the mechanical backlash and the correction for the equivalent bulk elastic modulus of the oil according to the same time sequence. Based on the aligned and combined mechanical backlash and the correction for the equivalent bulk elastic modulus of the oil, a system state vector is generated. The system state vector is a one-dimensional matrix containing a timestamp, gap value, and modulus value.

[0028] The dynamics modeling module receives the system state vector and extracts the equivalent bulk modulus correction of the hydraulic fluid and the mechanical backlash from it. The module then inputs the equivalent bulk modulus correction into a preset hydraulic dynamics equation to generate damping parameters. These equations include the fluid continuity equation and the servo valve flow equation. Substituting the equivalent bulk modulus correction into the fluid continuity equation, the module solves for the pressure derivative with respect to time, extracting the damping parameters characterizing the fluid's viscosity. Subsequently, the mechanical backlash is transformed into a step compensation term. This transformation uses the mechanical backlash as an input variable to a nonlinear dead-zone function, mapping the output to the step compensation term in the control system. A mechanical-hydraulic coupling state matrix is ​​constructed based on the damping parameters and the step compensation term. This matrix is ​​expressed in state-space form, with the damping parameters and the step compensation term as variable parameter matrix elements in state matrix A.

[0029] The dynamic modeling module jointly solves the mechanical-hydraulic coupling state matrix, generating phase difference data of the mechanical and hydraulic responses between the synchronous lead screw and the oscillating hydraulic cylinder. The solution process uses a Laplace transform to convert the mechanical-hydraulic coupling state matrix to a frequency domain transfer function, extracting the phase angle deviation of the transfer function at the system's crossing frequency as the phase difference data. Next, instability boundary parameters are extracted from the mechanical-hydraulic coupling state matrix. This extraction process uses the eigenvalues ​​of the mechanical-hydraulic coupling state matrix to obtain the critical values ​​where the real parts of the eigenvalues ​​approach the distance to the imaginary axis of the complex plane, which are then used as instability boundary parameters. The dynamic modeling module uses these instability boundary parameters as system stability boundary parameters and outputs them to the disturbance observation module.

[0030] The disturbance observation module receives the system stability boundary parameters output by the dynamic modeling module and transforms them into nonlinear weighting factors. The transformation process uses a normalization function to map the system stability boundary parameters to nonlinear weighting factors between zero and one. The disturbance observation module inputs these nonlinear weighting factors into a pre-defined observation model to generate a reconstructed state feedback gain matrix. The pre-defined observation model uses an extended state observer, and the feedback gain parameters of the extended state observer are dynamically adjusted using a pole placement algorithm with the nonlinear weighting factors to obtain the reconstructed state feedback gain matrix. Then, the system state vector is input into the reconstructed state feedback gain matrix to generate the trajectory of the landing gear in the state space before the test. The trajectory is generated by depicting a dynamic evolution sequence of angular displacement and angular velocity points on a phase plane diagram.

[0031] The disturbance observation module calculates the equilibrium divergence rate of the trajectory deviating from the preset equilibrium state. The preset equilibrium state is defined as the origin of the phase plane. The exponential growth rate of the trajectory points deviating from the origin of the phase plane over time is calculated using the Lyapunov exponential formula and taken as the equilibrium divergence rate. Then, the equilibrium divergence rate, mechanical backlash, and oil equivalent bulk elastic modulus correction are multiplied and exponentially calculated to generate the disturbance torque calculation value. The calculation logic is as follows: multiply the mechanical backlash and oil equivalent bulk elastic modulus correction as the base, use the equilibrium divergence rate as the exponent to form a power function, and substitute it into the disturbance torque estimation formula to obtain the disturbance torque calculation value. The disturbance observation module sends the disturbance torque calculation value as a nonlinear disturbance torque to the feedforward compensation calculation module.

[0032] The feedforward compensation calculation module receives the nonlinear disturbance torque from the disturbance observation module and the phase difference data of the mechanical and hydraulic responses between the synchronous lead screw and the oscillating hydraulic cylinder generated by the dynamic modeling module. The feedforward compensation calculation module performs integration calculations based on the phase difference data and the nonlinear disturbance torque, performing energy compensation calculations to generate the fluid compressible potential energy compensation. The calculation process uses the fourth-order Runge-Kutta method, performing time-discrete integration on the nonlinear disturbance torque within the time span corresponding to the given phase difference data to calculate the energy loss caused by gap lag, which is used as the fluid compressible potential energy compensation. Next, a feedforward compensation signal containing the fluid compressible potential energy compensation is generated based on this compensation. The generation process involves dividing the fluid compressible potential energy compensation by the system's equivalent fluid stiffness constant to obtain the predicted volumetric flow rate, which forms the feedforward compensation signal. The feedforward compensation calculation module converts the feedforward compensation signal into a pressure feedforward compensation quantity; the conversion process uses a digital-to-analog converter control chip to convert the feedforward compensation signal into a pressure feedforward compensation quantity with the corresponding voltage amplitude. The feedforward compensation calculation module outputs the pressure feedforward compensation amount to the instruction reconfiguration module.

[0033] The command reconstruction module uses the first load signal generated by the state perception module as the load signal of the subject's front landing gear, and receives the first load signal and the pressure feedforward compensation amount output by the feedforward compensation calculation module. The command reconstruction module performs state-space mapping calculations on the first load signal to generate discrete points of the load trajectory. The calculation process utilizes phase-space reconstruction technology, using the amplitude and rate of change of the first load signal as coordinate axes to map and project the one-dimensional time series signal onto a two-dimensional plane, forming discrete points of the load trajectory. Simultaneously, an ideal reference trajectory is generated based on a preset front wheel skidding dynamics model. The preset front wheel skidding dynamics model uses the magic formula tire model; by inputting the theoretical deflection angle and normal load, it solves for the reference friction torque curve, excluding stiffness coupling interference, as the ideal reference trajectory.

[0034] The instruction reconstruction module calculates the shortest mapping path from discrete points of the load trajectory to the ideal reference trajectory. The calculation process uses the Euclidean distance formula to obtain the set of normal perpendicular distances from each discrete point to the ideal reference trajectory, which serves as the shortest mapping path. Along the direction of the shortest mapping path, the instruction reconstruction module performs coordinate convergence calculations on the pressure feedforward compensation, executes error approximation control calculations, and generates the corrected pressure feedforward compensation. The calculation process employs a model predictive control algorithm, with the objective function being to shorten the shortest mapping path to zero. Within the control rolling optimization window, a gradient descent proportional adjustment is applied to the pressure feedforward compensation to obtain the corrected pressure feedforward compensation. The instruction reconstruction module generates a control current signal based on the corrected pressure feedforward compensation and transmits it to the hydraulic servo proportional valve. The process of generating the control current signal involves a pressure-controlled constant current source circuit that proportionally amplifies the corrected pressure feedforward compensation, converting it into a control current signal capable of driving the proportional valve's electromagnet.

[0035] The amplitude divergence threshold generated by the dynamic modeling module represents the absolute value of the maximum allowable alternating torque deviation of the control system. The control device sets the specific value of the amplitude divergence threshold to 120 Nm to 150 Nm. Simultaneously, the critical oscillation frequency generated by the dynamic modeling module is used to define the starting point of the high-frequency instability range caused by the coupling between the mechanical support structure and the hydraulic fluid. The control device configures the numerical range of the critical oscillation frequency to be 15 Hz to 25 Hz.

[0036] Within the program logic architecture of the state sensing module, a Butterworth low-pass filter with a cutoff frequency threshold is configured. The state sensing module sets the cutoff frequency threshold to 40 Hz to 50 Hz; using the set cutoff frequency threshold, the state sensing module filters out high-frequency electromagnetic interference noise during sensor line transmission.

[0037] The instruction reconstruction module relies on a path convergence threshold when performing error approximation control calculations. The instruction reconstruction module sets the path convergence threshold to 0.02 to 0.05 units and determines whether the pressure feedforward compensation has converged to the ideal reference trajectory based on the path convergence threshold.

[0038] The boundary thresholds for mapping and calculating the nonlinear weighting factor are included in the perturbation observation module. The perturbation observation module configures the boundary thresholds to 0.1 and 0.9, and limits the adjustment amplitude of the feedback gain parameter of the extended state observer based on the boundary thresholds.

[0039] Formula for calculating transient angular velocity:

[0040] In the formula, Represents transient angular velocity; Represents the current sampling time; This represents the first angular displacement signal of the landing gear at the current sampling time; This represents the result of the derivative operation of the first angular displacement signal with respect to the current sampling time.

[0041] Formula for calculating mechanical backlash:

[0042] In the formula, Represents mechanical backlash; The lead parameter represents the synchronous lead screw; This represents the time corresponding to the previous torque extreme point; This represents the time corresponding to the extreme point of the torque in the opposite direction. Represents transient angular velocity; Represents the transient angular velocity over a time period to The result of the absolute value integral operation within.

[0043] Formula for calculating the rate of change of transient pressure difference:

[0044] In the formula, Represents the rate of change of transient pressure difference; Represents the current sampling time; Represents the sampling time interval; This represents the first pressure signal of the swing hydraulic cylinder at the current sampling time. This represents the first pressure signal of the swing hydraulic cylinder at the previous sampling time.

[0045] Formula for calculating the correction to the equivalent bulk elastic modulus of oil:

[0046] In the formula, This represents the correction amount for the equivalent bulk elastic modulus of the oil. Represents the temperature influence coefficient; This represents the current ambient temperature parameter; Represents the pressure influence coefficient; This represents the rate of change of transient pressure difference.

[0047] Machine-fluid coupling state matrix equation:

[0048] In the formula, This represents the rate of change of the system state vector over time; This represents the state matrix of the machine-fluid coupling containing variable parameters; Represents the damping parameter; Represents the step compensation term; Represents the system state vector; The input control matrix represents the control device; This represents the system control input matrix.

[0049] Equilibrium divergence rate calculation formula:

[0050] In the formula, Represents the equilibrium divergence rate; This represents the time corresponding to the terminal trajectory point; This represents the time corresponding to the initial trajectory point; This represents the Euclidean distance at the end point of the trajectory from the preset equilibrium state; This represents the Euclidean distance by which the trajectory deviates from the preset equilibrium state from the initial trajectory point; This represents the function for operating on the natural logarithm.

[0051] Formula for calculating disturbance torque:

[0052] In the formula, This represents the calculated value of the disturbance torque; Represents the disturbance ratio coefficient; Represents mechanical backlash; This represents the correction amount for the equivalent bulk elastic modulus of the oil. This represents the equilibrium divergence rate.

[0053] Formula for calculating fluid compressible potential energy compensation:

[0054] In the formula, This represents the amount of fluid compressible potential energy compensation. Represents the current starting point; This represents the phase difference data between the mechanical and hydraulic responses of the synchronous lead screw and the oscillating hydraulic cylinder; Represents the variable during integration time. The nonlinear disturbance torque under the condition; Represents the integral variable.

[0055] Shortest mapping path calculation formula:

[0056] In the formula, Represents the shortest mapping path; The first coordinate value on the first coordinate axis represents the discrete point of the load trajectory. The second coordinate value representing the discrete point of the load trajectory on the second coordinate axis; The reference coordinate value representing the ideal reference trajectory on the first coordinate axis; The reference coordinate value representing the ideal reference trajectory on the second coordinate axis; This represents the function that performs the minimum value operation. This represents the square root operation function.

[0057] In the application scenario of high-speed runway correction for large passenger aircraft, the flight control system outputs weak and rapid correction commands to drive the nose wheel to deflect. Due to the response delay between the rotational torque generated by the hydraulic cylinder driven by hydraulic oil and the rigid support of the synchronous lead screw, high-frequency alternating torque oscillations are easily induced. To eliminate the alternating torque oscillation phenomenon, the state perception module collects the deflection angular displacement signal, lateral load signal, and pressure signal inside the cavity of the oscillating hydraulic cylinder in real time. By extracting transient change data including angular acceleration and pressure gradient, the state perception module constructs a system state vector composed of timestamp parameters, gap values, and oil bulk modulus parameters.

[0058] After the system state vector is generated, the dynamics modeling module receives the system state vector and calculates and generates system stability boundary parameters including the critical oscillation frequency and amplitude divergence threshold. Subsequently, the disturbance observation module uses an extended state observer as the preset observation model. The observation model is pre-constructed by collecting historical taxiing and yaw disturbance data of a large passenger aircraft and performing adaptive training on pole placement and gain parameters. During control operation, the observation model uses the nonlinear weighting factor transformed from the system stability boundary parameters and the system state vector as input variables. Within the observation model's operational logic, the model uses a nonlinear feedback control law to track the trajectory state of the subject's front landing gear in real time and outputs a nonlinear disturbance torque estimate that characterizes the degree of rigid-flexible coupling interference.

[0059] Combining the phase difference data of mechanical and hydraulic responses with the estimated nonlinear disturbance torque, the feedforward compensation calculation module calculates the fluid compression potential energy loss caused by the synchronous screw backlash and generates a pressure feedforward compensation amount containing the predicted fluid volumetric flow rate. The command reconfiguration module uses the load signal as a reference to perform error approximation control calculations on the pressure feedforward compensation amount, generating a control current signal that leads the mechanical hysteresis characteristics and transmitting it to the hydraulic servo proportional valve. Upon receiving the control current signal, the hydraulic servo proportional valve adjusts its valve opening in advance; before instability occurs due to the synchronous screw backlash, the hydraulic servo proportional valve pre-controls the flow rate and direction of the hydraulic oil entering the swing hydraulic cylinder. Utilizing the pre-established hydraulic oil pressure, the system can counteract the flexibility hysteresis of the mechanical support structure and smoothly drive the swing hydraulic cylinder, ultimately eliminating torque distortion and oscillation phenomena during the small-angle high-frequency correction stage.

Claims

1. A nose wheel steering loading device for an aircraft, characterized in that, It includes the main body of the equipment and a control device that establishes a communication connection with the main body of the equipment, and the control device controls the main body of the equipment; The control device includes: The state perception module receives the angular displacement signal of the front landing gear, the load signal of the front landing gear, and the pressure signal of the swing hydraulic cylinder collected by the measurement component. It performs calculations on the angular displacement signal, the load signal, and the pressure signal of the swing hydraulic cylinder to generate transient change data, and generates a system state vector based on the transient change data. The dynamic modeling module receives the system state vector, inputs the system state vector into the preset hydraulic dynamic equation to generate system stability boundary parameters, and generates phase difference data of mechanical and hydraulic responses between the synchronous screw and the swing hydraulic cylinder based on the system state vector. The disturbance observation module receives system stability boundary parameters and inputs them into a preset observation model to generate nonlinear disturbance torques. The feedforward compensation calculation module receives nonlinear disturbance torque and phase difference data of mechanical and hydraulic responses between the synchronous lead screw and the swing hydraulic cylinder. Based on the nonlinear disturbance torque and phase difference data of mechanical and hydraulic responses between the synchronous lead screw and the swing hydraulic cylinder, it performs energy compensation calculation to generate pressure feedforward compensation amount. The instruction reconfiguration module receives the pressure feedforward compensation amount and the load signal of the test landing gear. Based on the load signal of the test landing gear, it performs error approximation control calculation on the pressure feedforward compensation amount to generate a corrected pressure feedforward compensation amount. Based on the corrected pressure feedforward compensation amount, it generates a control current signal and transmits it to the hydraulic servo proportional valve. The hydraulic servo proportional valve receives a control current signal and adjusts the valve opening according to the control current signal. The valve opening controls the hydraulic oil entering the swing hydraulic cylinder to drive the swing hydraulic cylinder.

2. The aircraft nose wheel turning loading device according to claim 1, characterized in that, The state perception module is configured to: receive the angular displacement signal of the front landing gear, the load signal of the front landing gear, and the pressure signal of the swing hydraulic cylinder collected by the measurement component; filter the angular displacement signal, the load signal, and the pressure signal of the swing hydraulic cylinder to generate a first angular displacement signal, a first load signal, and a first pressure signal; and perform differential operation on the first angular displacement signal to generate a transient angular velocity. The first load signal is differentiated to generate the torque extremum point; the mechanical backlash of the threaded pair of the synchronous screw is calculated based on the transient angular velocity and the torque extremum point; the first pressure signal is differentiated to generate the transient pressure difference rate of change; the equivalent bulk elastic modulus correction of the oil is calculated based on the transient pressure difference rate of change, and the mechanical backlash and the equivalent bulk elastic modulus correction of the oil constitute transient change data; the mechanical backlash and the equivalent bulk elastic modulus correction of the oil are synchronously aligned and combined in the same time sequence, and the system state vector is generated based on the aligned and combined mechanical backlash and the equivalent bulk elastic modulus correction of the oil.

3. The aircraft nose wheel turning loading device according to claim 2, characterized in that, The dynamic modeling module is configured to: receive the system state vector; extract the oil equivalent bulk elastic modulus correction and mechanical backlash from the system state vector; and input the oil equivalent bulk elastic modulus correction into the preset hydraulic dynamics equation to generate damping parameters. The mechanical backlash is converted into a step compensation term; a mechanical-hydraulic coupling state matrix is ​​constructed based on the damping parameters and the step compensation term; the mechanical-hydraulic coupling state matrix is ​​solved jointly to generate the phase difference data of the mechanical and hydraulic responses between the synchronous lead screw and the swing hydraulic cylinder. Instability boundary parameters are extracted from the mechanical-hydraulic coupling state matrix; these instability boundary parameters are then used as system stability boundary parameters and output to the disturbance observation module.

4. The aircraft nose wheel turning loading device according to claim 3, characterized in that, The disturbance observation module is configured to: receive system stability boundary parameters output by the dynamic modeling module; convert the system stability boundary parameters into nonlinear weighting factors; input the nonlinear weighting factors into a preset observation model to generate a reconstructed state feedback gain matrix; input the system state vector into the reconstructed state feedback gain matrix to generate the trajectory of the landing gear in the state space before the test; calculate the equilibrium divergence rate of the trajectory deviating from the preset equilibrium state; perform multiplication and exponential operations on the equilibrium divergence rate, mechanical backlash, and oil equivalent bulk elastic modulus correction to generate a disturbance torque calculation value; and use the disturbance torque calculation value as a nonlinear disturbance torque and send it to the feedforward compensation calculation module.

5. The aircraft nose wheel turning loading device according to claim 4, characterized in that, The feedforward compensation calculation module is configured to: receive the nonlinear disturbance torque transmitted by the disturbance observation module, and the phase difference data of the mechanical and hydraulic responses between the synchronous lead screw and the swing hydraulic cylinder generated by the dynamic modeling module; perform integral calculation based on the phase difference data of the mechanical and hydraulic responses between the synchronous lead screw and the swing hydraulic cylinder and the nonlinear disturbance torque to perform energy compensation calculation and generate fluid compressive potential energy compensation amount. Generate a feedforward compensation signal containing the fluid compression potential energy compensation amount based on the fluid compression potential energy compensation amount; convert the feedforward compensation signal into a pressure feedforward compensation amount; and output the pressure feedforward compensation amount to the instruction reconfiguration module.

6. The aircraft nose wheel turning loading device according to claim 5, characterized in that, The instruction reconstruction module is configured to: use the first load signal generated by the state perception module as the load signal of the front landing gear of the test subject; receive the first load signal and the pressure feedforward compensation amount output by the feedforward compensation calculation module; perform state space mapping operation on the first load signal to generate discrete points of the load trajectory; and generate an ideal reference trajectory according to the preset front wheel skidding dynamics model. Calculate the shortest mapping path from discrete points of the load trajectory to the ideal reference trajectory; The pressure feedforward compensation amount is subjected to coordinate convergence calculation along the shortest mapping path to perform error approximation control calculation, generating the corrected pressure feedforward compensation amount; a control current signal is generated based on the corrected pressure feedforward compensation amount and transmitted to the hydraulic servo proportional valve.

7. The aircraft nose wheel turning loading device according to claim 6, characterized in that, The measurement components include a two-component force measurement unit and an angle measurement unit; the two-component force measurement unit is mounted on the front landing gear of the test subject; the angle measurement unit is mounted on the rotation axis of the front landing gear of the test subject; the two-component force measurement unit collects the load signal of the front landing gear of the test subject and sends it to the state perception module; the angle measurement unit collects the angular displacement signal of the front landing gear of the test subject and sends it to the state perception module; pressure measurement units are configured inside the two chambers of the swing hydraulic cylinder; the pressure measurement units collect the pressure signal of the swing hydraulic cylinder and send it to the state perception module.

8. The aircraft nose wheel steering loading device according to claim 7, characterized in that, In the main body of the equipment, a servo motor is connected to a synchronous lead screw; the synchronous lead screw is connected to the landing gear in front of the test subject; a displacement measurement unit is configured on the side of the synchronous lead screw; the displacement measurement unit collects lifting stroke data and feeds the lifting stroke data back to the control device; the control device receives the lifting stroke data and generates a speed adjustment command based on the lifting stroke data and sends it to the servo motor; the servo motor adjusts the motor speed according to the speed adjustment command.

9. The aircraft nose wheel steering loading device according to claim 8, characterized in that, The hydraulic servo proportional valve receives a control current signal; the hydraulic servo proportional valve adjusts the valve opening according to the control current signal; the valve opening controls the hydraulic oil entering the swing hydraulic cylinder, thereby adjusting the pressure inside the swing hydraulic cylinder; the pressure inside the swing hydraulic cylinder drives the swing hydraulic cylinder to output a turning torque.

10. An aircraft nose wheel steering loading system, applied to an aircraft nose wheel steering loading device as described in any one of claims 1 to 9, characterized in that, include: The state perception module receives the angular displacement signal of the front landing gear, the load signal of the front landing gear, and the pressure signal of the swing hydraulic cylinder collected by the measurement component. It performs calculations on the angular displacement signal, the load signal, and the pressure signal of the swing hydraulic cylinder to generate transient change data, and generates a system state vector based on the transient change data. The dynamic modeling module receives the system state vector, inputs the system state vector into the preset hydraulic dynamic equation to generate system stability boundary parameters, and generates phase difference data of mechanical and hydraulic responses between the synchronous screw and the swing hydraulic cylinder based on the system state vector. The disturbance observation module receives system stability boundary parameters and inputs them into a preset observation model to generate nonlinear disturbance torques. The feedforward compensation calculation module receives nonlinear disturbance torque and phase difference data of mechanical and hydraulic responses between the synchronous lead screw and the swing hydraulic cylinder. Based on the nonlinear disturbance torque and phase difference data of mechanical and hydraulic responses between the synchronous lead screw and the swing hydraulic cylinder, it performs energy compensation calculation to generate pressure feedforward compensation amount. The instruction reconfiguration module receives the pressure feedforward compensation amount and the load signal of the test landing gear. Based on the load signal of the test landing gear, it performs error approximation control calculation on the pressure feedforward compensation amount to generate a corrected pressure feedforward compensation amount. Based on the corrected pressure feedforward compensation amount, it generates a control current signal and transmits it to the hydraulic servo proportional valve. The hydraulic servo proportional valve receives a control current signal and adjusts the valve opening according to the control current signal. The valve opening controls the hydraulic oil entering the swing hydraulic cylinder to drive the swing hydraulic cylinder.

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