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The aviation intelligent pump system is an effective solution to aircraft hydraulic systems’ inefficient power consumption and temperature increase. A self-supplied aviation intelligent pump (SAIP) has a high power-to-weight ratio and compact structure, making it the optimal choice for an intelligent pump. To analyze the output characteristics of a novel aviation intelligent pump, it is crucial to establish an accurate mathematical model that describes its dynamic characteristics. This can be achieved by analyzing the working principle and exploring the influence of critical parameters. The paper introduces the composition and working principle of a self-supplied electro-hydraulic servo variable displacement pump. It then establishes a mathematical model of the whole pump, with a detailed analysis and modeling of the critical variable mechanism and the swash plate assembly’s load moment. A simulation model was created to examine the impact of crucial structural parameters, such as the offset spring’s stiffness and control piston’s diameter, on the output characteristics of the intelligent pump. An experimental platform was also constructed, and the experimental results confirm the accuracy of the SAIP model presented in this paper. The investigation of the output characteristics fully reveals the dynamic performance of the SAIP. This provides the basis for the subsequent design of high-performance flow and pressure control strategies and aids in researching intelligent aircraft hydraulic systems.

The planetary thread roller bearing (PTRB), as a new type of ball bearing, has the advantages of high-power density, no need to be used in pairs or combinations, and the ability to carry axial-radial combined load and bidirectional axial load. Its load distribution characteristics serve as the basis for building PTRB’s performance models, such as dynamic load rating, static load rating, and friction torque. In this paper, PTRB’s structure and the transmission paths of force were briefly introduced, and the elastic deformation of the threaded roller, inner ring, and outer ring was analyzed on the basis of the Hertz theory and Hooke’s law. Next, the methods for calculating the compressive deformation of shaft when PTRB was under different load states were presented. In view of the nonlinear relation between force and elastic deformation as well as the compatibility equation, the theoretical model of PTRB’s load distribution was set up accordingly. There was a discrepancy between the variation trends and values of load distribution under four axial load states, with a larger load distribution coefficient at the contact point closer to the flange. With the increase of load from 10 to 30 kN, the increase rates of the axial and radial load distribution coefficients were ≯1.2%, so that the load distribution coefficient could be approximately deemed as an inherent characteristic of PTRB. Within the value range of each structural parameter, the variation of the pitch diameter of threaded roller had the most significant effect on axial load distribution coefficient, with a variation rate of 7%; the variation of the number of threaded rollers had a significant effect on radial load distribution coefficient, with a variation rate of 37%; the variation of the remaining structural parameters had a minimal effect on load distribution coefficient, with a variation rate of ≯3%. When a follow-up optimization design is conducted on the performance of PTRB with a fixed dimension, and the contact angle, number of thread teeth per roller, and pitch diameter of threaded roller are deemed as design variables, the load distribution coefficient can be set as a constant value, and the number of threaded rollers can be set as the maximum value to simplify the optimization design process of PTRB’s performance and improve the optimization design efficiency.

The control accuracy and stability of the electrohydrostatic actuator (EHA) are directly impacted by parameter uncertainty, disturbance uncertainty, and non-matching disturbance, which negatively impacts aircraft rudder maneuvering performance and even results in rudder chatter. A dynamic surface-based adaptive active disturbance rejection control (DSAADRC) is proposed as a solution for these issues. It does this by developing a novel parametric adaptive law driven by the combination of tracking error, parameter estimation error, and state estimation error to estimate the unknown parameters, using three low-order ESOs to estimate and compensate the uncertain disturbances online, and employing a dynamic surface method to obtain the differential values of virtual control signals in the backstepping method to deal with non-matching disturbances. In this research, a Lyapunov stability analysis demonstrates that the method can achieve the position tracking accuracy of the EHA under time-varying external disturbances after first establishing an EHA dynamics model with nonlinearity and uncertainty, followed by the design of an adaptive active disturbance rejection control method based on dynamic surfaces for the uncertainties and perturbations. In contrast to control strategies like Robust Control (RC) and Adaptive Robust Control (ARC), simulation and experiment comparison shows that the method has stronger anti-disturbance under time-varying external disturbances.

With technological advances and industrial upgrading, high-performance equipment has put higher demands on the performance of electro-mechanical actuators. With a view to making electro-mechanical actuators more reliable and integrated, firstly, an integrated electro-mechanical actuator module (IEMM) with multiple structural forms was proposed in this paper, and a comparative analysis was performed on the characteristics of different transmission schemes. Then, the feasibility of manufacturing the IEMM’s main bearing components using Carbon Fiber Reinforced Polymer (CFRP) with higher specific stiffness, specific modulus and specific strength was demonstrated by finite element simulation (FEA) software, in a bid to further reduce the weight of the IEMM. Next, a parameter estimation model, a heating power calculation model, and a thermal resistance calculation model were built, so that there is no need to rebuild the whole system model under different demand indexes. On this basis, a multi-objective optimization design model was built with light weight, low power loss, and high level of integration as optimization aims to achieve better comprehensive performance in the early design phase of the IEMM system. However, IEMM’s higher level of integration and its shell made of CFRP with a thermal conductivity of less than 5 W/m°C posed a challenge to the heat dissipation of the motor stator. Therefore, a thermal network model needs to be created in AMESim to evaluate the temperature of IEMM’s parts and components under different working conditions. Finally, the process of IEMM performance optimization design was described and improved, and performance optimization design was conducted by taking one of IEMM’s transmission schemes as an example.

CAR T therapy has some efficacy in the treatment of patients with refractory/relapsed B-cell acute lymphoblastic leukemia; however in some patients further relapse is encountered. Here, the authors conduct a Phase II clinical trial of a CD19 CAR T and demonstrate that patients with extramedullary disease are more likely to relapse than those without.

For electro-hydrostatic actuators (EHAs), how to estimate and compensate for the combined effects of the severe nonlinearity caused by inner leakage and friction, the parametric uncertainties of the hydraulic components due to the environment and the external disturbance remain the primary issues. In this paper, a novel four-loop cascade control based on the active disturbance compensation method was proposed to address the abovementioned problem. First, by dividing the model of an EHA, two low-order estimators were obtained rather than a high-order estimator, which are easier to be implemented. Further, pressure information of two chambers of the EHA was applied in the proposed controller to compensate for the mismatching disturbances directly. Finally, the experimental results proved that the proposed method improved the robustness and static state error by approximately 35% and 33%, respectively.

Bearings, as integral parts and components in machinery and equipment, play a critical role in system performance. In this paper, the theoretical models of basic axial load rating, basic radial load rating, and friction torque for the planetary thread roller bearing (PTRB) were derived. Then, a detailed comparison was made between the performance indexes of a PTRB prototype and common high-quality bearing products to demonstrate the advantages of PTRB in volume, bearing capacity, and use method. Next, the effects of different structural parameters on the performance indexes of PTRB were analyzed. On this basis, a multi-objective optimization design was carried out on PTRB under axial load and radial load separately with basic load rating and friction torque as optimization objects to obtain PTRB with superior comprehensive performance. Designers could, in consideration of their specific needs and optimized design results, select the structural parameters of PTRB. Furthermore, a dedicated performance test system was researched and developed, which verified the good static bearing capacity and impact resistance of the PTRB prototype. Within the range of dynamic load rating, the test data were slightly larger than the simulation data for the friction torque, manifesting a relatively high degree of precision of the theoretical model.

Electro-hydrostatic actuators (EHAs) are expanding their application fields due to their combined advantages of electric and hydraulic actuation. However, the control performance, the weight, and the efficiency turn out to be more challenging requirements when the EHA power level increases to over 30 kW. Therefore, a preliminary design dedicated to trading off the system-level EHA performance based on multi-domain coupling analysis is necessary considering the comprehensive performance requirements and the parameter uncertainties. However, the existing methods are deficient in responding to all these design challenges. In this paper, an EHA preliminary design method is proposed to achieve the optimum system-level performance with robustness. First, the design parameters are analyzed and selected. Second, an optimization design of EHAs is realized by developing multi-disciplinary performance simulation models. The robustness is also considered during the optimization design. Third, the optimization results are evaluated by a specifically built EHA model, which realizes high fidelity than the models used for optimization. As a result, the general high-power EHA requirements are fully considered during the preliminary design and an optimum EHA performance is achieved. The proposed method is demonstrated in a design case of a 30 kW EHA for aerospace applications, which achieved the optimum performance of 8 Hz bandwidth and 69.92 kg weight. The preliminary design results also outline the input information for the following detailed design. Therefore, the proposed method demonstrated its applicability for delivering robust EHA design results for engineering applications.

A planetary thread roller bearing (PTRB) is a state-of-the-art component in electromechanical actuators (EMA) due to its high load-bearing capacity and small volume. The study of the PTRB is a leading task in the domain of EMA application. In this study, we propose a mathematical model of PTRB friction torque on its working principle and causes. Specifically, the impact of basic properties of the PTRB on friction torque, i.e., rotating speed and external load, are modeled and analyzed. To verify the variation principle of friction torque, experiments are carried out on an actual PTRB. For the test PTRB, the rotating speed ranges from 200 to 2000 rpm with a reverse load from 2000 to 30,000 N at a constant temperature of 55 °C. Experimental results verify the effectiveness of the mathematical model under conditions of 200–2000 rpm rotating speed and 2000–30,000 N external load, which establish strong evidence for model accuracy and robustness.

A dynamic load simulator, which can reproduce on-ground aerodynamic hinge moment of control surface, is an essential rig for the performance and stability test of an aircraft actuation system. In this paper, an observer-based backstepping adaptive control (OBAC) strategy with an improved friction model is proposed to deal with the force tracking problem of an electro-mechanical actuator under the influence of nonlinear friction and lumped disturbances. First, The LuGre friction model is improved by introducing the load effect of electrical linear load simulator (ELLS), and both dynamic and static parameters are identified with experimental data. Then, the ELLS system is divided into a loading subsystem and actuation subsystem for backstepping controller deign. The estimation of the position disturbance is obtained using an extended state observer and used for feedforward compensation for the loading subsystem. To reject the disturbance of friction parameter uncertainties for actuation subsystem, a friction scale factor with a reasonable adaptive updating law is introduced during the friction compensation process. Finally, the stability of the whole closed-loop system is demonstrated using a Lyapunov-based method, and experiments are performed to validate the effectiveness of the developed algorithm.

To improve the penetration capability and the damage effectiveness of cruise missiles, maneuvering trajectory with specific impact angle is applied in terminal guidance. In this paper, an innovative online method for terminal guidance is presented, which can guide the cruise missile to a stationary target along a climb-and-dive maneuvering trajectory while meeting the expected impact angle. The basic principles of the proposed guidance method are the Bézier curve theory and the missile inverse dynamics. The maneuvering trajectory is shaped by a third-order Bézier curve based on the missile current state, the target position, and the impact angle constraint. The real-time guidance command represented by attack angle $\alpha $ is obtained based on the missile inverse dynamics. The shape of flight trajectory can be modified by regulating the Bézier parameters $b_{1}$ and $b_{2}$ to satisfy different tactical requirements without changing the boundary conditions. Simulation results demonstrate the effectiveness of the proposed method applied in cruise missile terminal guidance.

A concept of a new energy management system synthesizing meteorological and orographic influences on airplane safety envelope was developed and implemented at the ZHAW Centre for Aviation. A corresponding flight simulation environment was built in a Research and Didactics Simulator (ReDSim) to test the first implementation of the cockpit display system. A series of pilot-in-the-loop flight simulations were carried out with a group of pilots. A general aviation airplane model Piper PA-28 was modified for the study. The environment model in the ReDSim was modified to include a new ad hoc subsystem simulating atmospheric disturbance. In order to generate highly resolved wind fields in the ReDsim, a well-established large-eddy simulation model, the Parallelized Large-Eddy Simulation (PALM) framework, was used in the concept study, focusing on a small mountainous region in Switzerland, not far from Samedan. For a more realistic representation of specific meteorological situations, PALM was driven with boundary conditions extracted from the COSMO-1 reanalysis of MeteoSwiss. The essential variables (wind components, temperature, and pressure) were extracted from the PALM output and fed into the subsystem after interpolation to obtain the values at any instant and any aircraft position. Within this subsystem, it is also possible to generate statistical atmospheric turbulence based on the widely used Dryden turbulence model. The paper compares two ways of generating atmospheric turbulence, by combining the numerical method with the statistical model and introduces the flight test procedure with an emphasis on turbulence realism; it then presents the experiment results including a statistical assessment achieved by collecting pilot feedback on turbulence characteristics and turbulence/task combination.

Electromechanical actuators (EMAs) have shown a high efficiency in flight surface control with the development of more electric aircraft. In order to identify the abnormalities and potential failures of EMA, a methodology for fault diagnosis is developed. A simulating model of EMA is first built to perform different working states. Based on the modeling of EMA, the corresponding faults are then simulated to re-generate the fault data. Afterwards, a gated recurrent unit (GRU) and co-attention-based fault diagnosis approach is proposed to classify the working states of EMA. Experiments are conducted and a satisfying classification accuracy on simulated data is obtained. Furthermore, fault diagnosis on an actual working system is performed. The experimental results demonstrate that the proposed method has a high efficiency.

With the development of more/all electric aircraft, replacement of the traditional hydraulic servo actuator (HSA) with an electromechanical actuator (EMA) is becoming increasingly attractive in the aerospace field. This paper takes an EMA for a trimmable horizontal stabilizer as an example and focuses on how to establish a system model with an appropriate level of complexity to support the model-based system engineering (MBSE) approach. To distinguish the nonlinear effects that dominate the required system performance, an incremental approach is proposed to progressively introduce individual nonlinear effects into models with different complexity levels. Considering the special design and working principle of the mechanical power transmission function for this actuator, the nonlinear dynamics, including friction and backlash from the no-back mechanism, and the nonlinear compliance effect from the mechanical load path are mainly taken into consideration. The modelling principles for each effect are addressed in detail and the parameter identification method is utilized to model these nonlinear effects realistically. Finally, the responses from each model and experimental results are compared to analyze and verify how each individual nonlinearity affects the system’s performance.

An electrohydrostatic actuator (EHA) is a basic mechanical/hydraulic system with deficiencies including significant nonlinearity and parametric uncertainties. In line with the challenges of designing a high-precision control strategy, an adaptive damping variable sliding mode controller is established, which extends our previous work on EHA control. The proposed controller integrates variable-damping sliding mode control, parametric adaptation, and an extended state observer. The parametric uncertainties are effectively captured and compensated by employing an adaptive control law, while system uncertainties are reduced, and disturbances are estimated and compensated with a fast and stable response. We evaluated the proposed control strategy on a variety of position tracking tasks. The experimental results demonstrate that our controller significantly outperforms the widely used methods in overshoot suppression, settling time, and tracking accuracy.

Electro-hydrostatic actuator (EHA) has significance in a variety of industrial tasks. For the purpose of elevating the working performance, we put forward a sliding mode control strategy for EHA operation with a damping variable sliding surface. To start with, a novel sliding mode controller and an extended state observer (ESO) are established to perform the proposed control strategy. Furthermore, based on the modeling of the EHA, simulations are carried out to analyze the working properties of the controller. More importantly, experiments are conducted for performance evaluation based on the simulation results. In comparison to the widely used control strategies, the experimental results establish strong evidence of both overshoot suppression and system rapidity.

The distribution of ranging errors of time of arrival techniques fails to satisfy zero means and equal variances. It is one of the major causations of position error of least square–based localization algorithm. The optimization of time of arrival ranging is defined as a nonlinear programming problem. Then, time of arrival ranging error model and geometric constraints are used to define the initial values, objective functions, and constraints of nonlinear programming, as well as to detect line of sight and nonline of sight. A three-dimensional localization algorithm of an indoor time of arrival–based positioning is proposed based on least square and the optimization algorithm. The performance of the ranging and localization accuracies is evaluated by simulation and field testing. Results show that the optimized ranging error successfully satisfies zero mean value and equal variances. Furthermore, the ranging and localization accuracies are significantly improved.

This paper aims to deal with the problem of rotor position estimation and compensation for a magnetically suspended flywheel energy storage system under the consideration of measurement noise and unknown disturbances. First, the flywheel system working principle and description are analyzed and, based on this, the mathematical model as well as the coordinates transformation are introduced. For the purpose of the state estimation, a two-step extended sliding-mode observer is considered to obtain the estimates of the rotor angular position. In this control strategy, a traditional sliding-mode observer is adopted as a first-step original state estimator. After that, the relationship between the angular position and the estimation error is established and a second-step observer is designed to obtain the estimation of the error. The estimated error is then used to compensate the real values of the rotor angular position generated by the first-step observer. To reject the influences of the measurement noise and unknown disturbances, the H∞ optimization strategy is considered to determine the second-step observer structure. Finally, experimental results are presented to demonstrate the effectiveness of the proposed method. It is demonstrated that the proposed two-step observer method has a better estimation accuracy and control performance.

Condition monitoring of hydraulic systems has been using automatic control in industrial system. In this paper, a sensor network based intelligent control is proposed for efficient solenoid valve identification. The detection system learns to detect the change of output pressure of multipoints that represent a more complicated task. Linear correlation analysis is introduced for feature extraction, which allows for a significant reduction in the dimension of original data without compromising the change detection performance. Implemented as an agent identifying the valve types under measurement, the support vector machine classifier achieves a significant high accuracy in identification and an increase in deployment efficiency. Experimental results prove that the system is feasible for application designs and could be implemented on technological platforms.