Aiming to improve the pull-up control performance in the process of releasing balloonborne solar powered UAVs(Unmanned Aerial Vehicles),this paper establishes the full flight mechanics equations with flexible modes,an...Aiming to improve the pull-up control performance in the process of releasing balloonborne solar powered UAVs(Unmanned Aerial Vehicles),this paper establishes the full flight mechanics equations with flexible modes,and proposes the control method suitable for engineering application.To be specific,the authors first calculate the real aerodynamic force on horizontal stabilizer by comparing the fuselage deformation in ballooning test with that in static loading test.Furthermore,considering fuselage elastic deformation,the pitching moment coefficient is obtained and the influence of airspeed and elevator angle on pitching moment coefficient and control surface efficiency are analysed.Second,the authors establish a complete flight mechanics model,including elastic structural dynamic model and rigid flight dynamic model,by comprehensively considering the aerodynamic data,the relationship between fuselage deformation and load,as well as the ballooning test.Third,the authors perform the numerical simulation and comparison study on control performance between rigid model and flexible model.Moreover,the authors implement model modification based on the low altitude flight test and steady-state point analysing.Finally,a scaled UAV is used to complete the balloon-borne launching test.The results show that the longitudinal control method can analyse the longitudinal aerodynamics and control characteristics accurately,and could be effectively utilized in the pull-up control of the balloon-borne solar powered UAV.展开更多
Purpose–This paper aims to address the longitudinal control problem for person-following robots(PFRs)for the implementation of this technology.Design/methodology/approach–Nine representative car-following models are...Purpose–This paper aims to address the longitudinal control problem for person-following robots(PFRs)for the implementation of this technology.Design/methodology/approach–Nine representative car-following models are analyzed from PFRs application and the linear model and optimal velocity model/full velocity difference model are qualified and selected in the PFR control.Findings–A lab PFR with the bar-laser-perception device is developed and tested in the field,and the results indicate that the proposed models perform well in normal person-following scenarios.Originality/value–This study fills a gap in the research on PRFs longitudinal control and provides a useful and practical reference on PFRs longitudinal control for the related research.展开更多
To successfully implement the platoon control of connected and automated vehicles,it is necessary to address motion control issues to achieve longitudinal and lateral collaborative control.However,due to traffic capac...To successfully implement the platoon control of connected and automated vehicles,it is necessary to address motion control issues to achieve longitudinal and lateral collaborative control.However,due to traffic capacity limitations and the complex traffic environment in which autonomous and human-driven vehicles coexist,autonomous platoon faces significant risks and challenges.This paper investigates longitudinal and lateral control issues from the perspective of a single vehicle up to a platoon,simulating the performance and suitability of various controllers.First,a longitudinal controller based on fuzzy logic and PID control is employed for speed tracking control of a single vehicle,followed by the adoption of an MPC controller based on the vehicle kinematics model to realize the lateral motion of a single vehicle.Second,the communication methods of the autonomous platoon are discussed,and the longitudinal controller that considers the platoon's various communication topologies is developed.Thirdly,a framework for robust integrated motion control is established,which combines the robust H-infinity longitudinal controller and the APF-based MPC lateral controller.Simulation results validate the effectiveness of the aforementioned controllers and reveal their limitations.展开更多
To develop vortex generator jet （VGJ） method for flow control, the turbulence flow in a 14° conical diffuser with and without vortex generator jets are simulated by solving Navier-Stokes equations with k-ε tur...To develop vortex generator jet （VGJ） method for flow control, the turbulence flow in a 14° conical diffuser with and without vortex generator jets are simulated by solving Navier-Stokes equations with k-ε turbulence model. The diffuser performance, based on different velocity ratio （ratio of the jet speed to the mainstream velocity）, is investigated and compared with the experimental study. On the basis of the flow characteristics using computation fluid dynamics （CFD） method observed in the conical diffuser and the downstream development of the longitudinal vortices, attempt is made to correlate the pressure recovery coefficient with the behavior of vortices produced by vortex generator jets.展开更多
Aircraft longitudinal control is the would lead to catastrophic accident of aircraft. most important actuation system and its failures This paper proposes an active fault-tolerant control （AFTC） strategy for civil a...Aircraft longitudinal control is the would lead to catastrophic accident of aircraft. most important actuation system and its failures This paper proposes an active fault-tolerant control （AFTC） strategy for civil aircraft with different numbers of faulty elevators. In order to improve the fault-tolerant flight control system performance and effective utilization of the control surface, trim- mable horizontal stabilizer （THS） is considered to generate the extra pitch moment. A suitable switching mechanism with performance improvement coefficient is proposed to determine when it is worthwhile to utilize THS. Furthermore, AFTC strategy is detailed by using model following technique and the proposed THS switching mechanism. The basic fault-tolerant controller is designed to guarantee longitudinal control system stability and acceptable performance degradation under partial elevators failure. The proposed AFTC is applied to Boeing 747-200 numerical model and simulation results validate the effectiveness of the proposed AFTC approach.展开更多
For conventional adaptive control, time-varying parametric uncertainty and unmodeled dynamics are ticklish problems, which will lead to undesirable performance or even instability and nonrobust behavior, respectively....For conventional adaptive control, time-varying parametric uncertainty and unmodeled dynamics are ticklish problems, which will lead to undesirable performance or even instability and nonrobust behavior, respectively. In this study, a class of discrete-time switched systems with unmodeled dynamics is taken into consideration. Moreover, nonlinear systems are here supposed to be approximated with the class of switched systems considered in this paper, and thereby switching control design is investigated for both switched systems and nonlinear systems to assure stability and performance. For robustness against unmodeled dynamics and uncertainty, robust model reference adaptive control(RMRAC) law is developed as the basis of controller design for each individual subsystem in the switched systems or nonlinear systems. Meanwhile, two different switching laws are presented for switched systems and nonlinear systems, respectively. Thereby, the authors incorporate the corresponding switching law into the RMRAC law to construct two schemes of switching control respectively for the two kinds of controlled systems. Both closed-loop analyses and simulation examples are provided to illustrate the validity of the two proposed switching control schemes. Furthermore, as to the proposed scheme for nonlinear systems, its potential for practical application is demonstrated through simulations of longitudinal control for F-16 aircraft.展开更多
Motivated by the promising benefits of connected and autonomous vehicles (CAVs) in improving fuelefficiency, mitigating congestion, and enhancing safety, numerous theoretical models have been proposed to plan CAVmulti...Motivated by the promising benefits of connected and autonomous vehicles (CAVs) in improving fuelefficiency, mitigating congestion, and enhancing safety, numerous theoretical models have been proposed to plan CAVmultiple-step trajectories (time–specific speed/location trajectories) to accomplish various operations. However, limitedefforts have been made to develop proper trajectory control techniques to regulate vehicle movements to follow multiplesteptrajectories and test the performance of theoretical trajectory planning models with field experiments. Without aneffective control method, the benefits of theoretical models for CAV trajectory planning can be difficult to harvest. This studyproposes an online learning-based model predictive vehicle trajectory control structure to follow time–specific speed andlocation profiles. Unlike single-step controllers that are dominantly used in the literature, a multiple-step model predictivecontroller is adopted to control the vehicle’s longitudinal movements for higher accuracy. The model predictive controlleroutput (speed) cannot be interpreted by vehicles. A reinforcement learning agent is used to convert the speed value to thevehicle’s direct control variable (i.e., throttle/brake). The reinforcement learning agent captures real-time changes in theoperating environment. This is valuable in saving parameter calibration resources and improving trajectory control accuracy.A line tracking controller keeps vehicles on track. The proposed control structure is tested using reduced-scale robot cars.The adaptivity of the proposed control structure is demonstrated by changing the vehicle load. Then, experiments on twofundamental CAV platoon operations (i.e., platooning and split) show the effectiveness of the proposed trajectory controlstructure in regulating robot movements to follow time-specific reference trajectories.展开更多
基金supported by the Beijing Natural Science Foundation under Grant No.4222050the National Natural Science Foundation of China under Grant No.62173030。
文摘Aiming to improve the pull-up control performance in the process of releasing balloonborne solar powered UAVs(Unmanned Aerial Vehicles),this paper establishes the full flight mechanics equations with flexible modes,and proposes the control method suitable for engineering application.To be specific,the authors first calculate the real aerodynamic force on horizontal stabilizer by comparing the fuselage deformation in ballooning test with that in static loading test.Furthermore,considering fuselage elastic deformation,the pitching moment coefficient is obtained and the influence of airspeed and elevator angle on pitching moment coefficient and control surface efficiency are analysed.Second,the authors establish a complete flight mechanics model,including elastic structural dynamic model and rigid flight dynamic model,by comprehensively considering the aerodynamic data,the relationship between fuselage deformation and load,as well as the ballooning test.Third,the authors perform the numerical simulation and comparison study on control performance between rigid model and flexible model.Moreover,the authors implement model modification based on the low altitude flight test and steady-state point analysing.Finally,a scaled UAV is used to complete the balloon-borne launching test.The results show that the longitudinal control method can analyse the longitudinal aerodynamics and control characteristics accurately,and could be effectively utilized in the pull-up control of the balloon-borne solar powered UAV.
基金supported by the Basal Research Fund of Central Public Research Institute of China(Grant No.20212702).
文摘Purpose–This paper aims to address the longitudinal control problem for person-following robots(PFRs)for the implementation of this technology.Design/methodology/approach–Nine representative car-following models are analyzed from PFRs application and the linear model and optimal velocity model/full velocity difference model are qualified and selected in the PFR control.Findings–A lab PFR with the bar-laser-perception device is developed and tested in the field,and the results indicate that the proposed models perform well in normal person-following scenarios.Originality/value–This study fills a gap in the research on PRFs longitudinal control and provides a useful and practical reference on PFRs longitudinal control for the related research.
基金The authors would like to appreciate the financial support of National Key R&D Program of China:2022YFB2503003 and 2020YFB1600303the National Natural Science Foundation of China Project:U1964203,52221005 and 52072215.
文摘To successfully implement the platoon control of connected and automated vehicles,it is necessary to address motion control issues to achieve longitudinal and lateral collaborative control.However,due to traffic capacity limitations and the complex traffic environment in which autonomous and human-driven vehicles coexist,autonomous platoon faces significant risks and challenges.This paper investigates longitudinal and lateral control issues from the perspective of a single vehicle up to a platoon,simulating the performance and suitability of various controllers.First,a longitudinal controller based on fuzzy logic and PID control is employed for speed tracking control of a single vehicle,followed by the adoption of an MPC controller based on the vehicle kinematics model to realize the lateral motion of a single vehicle.Second,the communication methods of the autonomous platoon are discussed,and the longitudinal controller that considers the platoon's various communication topologies is developed.Thirdly,a framework for robust integrated motion control is established,which combines the robust H-infinity longitudinal controller and the APF-based MPC lateral controller.Simulation results validate the effectiveness of the aforementioned controllers and reveal their limitations.
基金This project is supported by Scientific Research Foundation of Ministry of Education of China for Returnee.
文摘To develop vortex generator jet （VGJ） method for flow control, the turbulence flow in a 14° conical diffuser with and without vortex generator jets are simulated by solving Navier-Stokes equations with k-ε turbulence model. The diffuser performance, based on different velocity ratio （ratio of the jet speed to the mainstream velocity）, is investigated and compared with the experimental study. On the basis of the flow characteristics using computation fluid dynamics （CFD） method observed in the conical diffuser and the downstream development of the longitudinal vortices, attempt is made to correlate the pressure recovery coefficient with the behavior of vortices produced by vortex generator jets.
基金supported by the National Natural Science Foundation of China(No.51305011)the National Basic Research Program of China(No.2014CB046402)the111 Project of China
文摘Aircraft longitudinal control is the would lead to catastrophic accident of aircraft. most important actuation system and its failures This paper proposes an active fault-tolerant control （AFTC） strategy for civil aircraft with different numbers of faulty elevators. In order to improve the fault-tolerant flight control system performance and effective utilization of the control surface, trim- mable horizontal stabilizer （THS） is considered to generate the extra pitch moment. A suitable switching mechanism with performance improvement coefficient is proposed to determine when it is worthwhile to utilize THS. Furthermore, AFTC strategy is detailed by using model following technique and the proposed THS switching mechanism. The basic fault-tolerant controller is designed to guarantee longitudinal control system stability and acceptable performance degradation under partial elevators failure. The proposed AFTC is applied to Boeing 747-200 numerical model and simulation results validate the effectiveness of the proposed AFTC approach.
基金supported by Deep Exploration Technology and Experimentation Project under Grant No.201311194-04partially supported by the National Natural Science Foundation of China under Grant Nos.61321002 and 61473038+1 种基金Beijing Outstanding Talents Programme under Grant No.2012D009011000003Graduate Teaching/Innovation Funding of Beijing Institute of Technology
文摘For conventional adaptive control, time-varying parametric uncertainty and unmodeled dynamics are ticklish problems, which will lead to undesirable performance or even instability and nonrobust behavior, respectively. In this study, a class of discrete-time switched systems with unmodeled dynamics is taken into consideration. Moreover, nonlinear systems are here supposed to be approximated with the class of switched systems considered in this paper, and thereby switching control design is investigated for both switched systems and nonlinear systems to assure stability and performance. For robustness against unmodeled dynamics and uncertainty, robust model reference adaptive control(RMRAC) law is developed as the basis of controller design for each individual subsystem in the switched systems or nonlinear systems. Meanwhile, two different switching laws are presented for switched systems and nonlinear systems, respectively. Thereby, the authors incorporate the corresponding switching law into the RMRAC law to construct two schemes of switching control respectively for the two kinds of controlled systems. Both closed-loop analyses and simulation examples are provided to illustrate the validity of the two proposed switching control schemes. Furthermore, as to the proposed scheme for nonlinear systems, its potential for practical application is demonstrated through simulations of longitudinal control for F-16 aircraft.
基金sponsored by the National Science Foundation(CMMI#1558887 and CMMI#1932452).
文摘Motivated by the promising benefits of connected and autonomous vehicles (CAVs) in improving fuelefficiency, mitigating congestion, and enhancing safety, numerous theoretical models have been proposed to plan CAVmultiple-step trajectories (time–specific speed/location trajectories) to accomplish various operations. However, limitedefforts have been made to develop proper trajectory control techniques to regulate vehicle movements to follow multiplesteptrajectories and test the performance of theoretical trajectory planning models with field experiments. Without aneffective control method, the benefits of theoretical models for CAV trajectory planning can be difficult to harvest. This studyproposes an online learning-based model predictive vehicle trajectory control structure to follow time–specific speed andlocation profiles. Unlike single-step controllers that are dominantly used in the literature, a multiple-step model predictivecontroller is adopted to control the vehicle’s longitudinal movements for higher accuracy. The model predictive controlleroutput (speed) cannot be interpreted by vehicles. A reinforcement learning agent is used to convert the speed value to thevehicle’s direct control variable (i.e., throttle/brake). The reinforcement learning agent captures real-time changes in theoperating environment. This is valuable in saving parameter calibration resources and improving trajectory control accuracy.A line tracking controller keeps vehicles on track. The proposed control structure is tested using reduced-scale robot cars.The adaptivity of the proposed control structure is demonstrated by changing the vehicle load. Then, experiments on twofundamental CAV platoon operations (i.e., platooning and split) show the effectiveness of the proposed trajectory controlstructure in regulating robot movements to follow time-specific reference trajectories.
