Longitudinal Control System Research Articles

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English

Aircraft nonlinear optimal control using fuzzy gain scheduling

Fuzzy gain scheduling is a common solution for nonlinear flight control. The highly nonlinear region of flight dynamics is determined throughout the examination of eigenvalues and the irregular pattern of root locus plots that show the nonlinear characteristic. By using the optimal control for command tracking, the pitch rate stability augmented system is constructed and the longitudinal flight control system is established. The outputs of optimal control for 21 linear systems are fed into the fuzzy gain scheduler. This research explores the capability in using both optimal control and fuzzy gain scheduling to improve the efficiency in finding the optimal control gains and to achieve Level 1 flying qualities. The numerical simulation work is carried out to determine the effectiveness and performance of the entire flight control system. The simulation results show that the fuzzy gain scheduling technique is able to perform in real time to find near optimal control law in various flying conditions.

Nonlinear longitudinal attitude control of an unmanned seaplane with wave filtering

A new longitudinal attitude control system design for an unmanned seaplane in the severe sea states is presented in this paper. We develop a nonlinear passive observer, which is used to achieve wave filtering and state estimation. Moreover, the observer can be extended to achieve adaptive wave filtering in varying sea states. Using the estimated low-frequency states, a backstepping sliding mode controller is designed to keep the longitudinal attitude of the unmanned seaplane stable. The stability of the total closed loop system is analyzed by using Lyapunov theory. Simulations are performed in different wave conditions, including Seastate 3 and Seastate 5. The simulations results show that the proposed longitudinal attitude controller can improve the anti-waves capability effectively. Moreover, adaptive wave filter has a significant advantage over a filter with fixed model parameters in varying sea states.

Model-reduced fault detection for multi-rate sensor fusion with unknown inputs

In multi-sensor fusion, it is hard to guarantee that all sensors work at the single sampling rate, especially in the distributive and/or heterogeneous case, and fault detection (FD) in multi-rate sensor fusion may face the existence of unknown inputs (UIs) in complex environment. Meanwhile, model reduction often refers to propose a possible lower-dimensional model to replace the original model without adding significant error in practical applications. By the fact that FD in dynamic systems should only focus on the fault-related controllability and observability characteristics, it is a good idea to obtain the fault-related controllable and observable subsystem via system decomposition (i.e., model reduction) for FD. Such a kind of model reduction not only guarantee the FD performance, but also reduce the system dimensions. To this end, we propose the model-reduced fault detection (MRFD) problem for multi-rate sensor fusion subject to UIs and faults imposed on the actuator and sensors. Our aim is to design a fast and computation-effective FD scheme based on the reduced model. We use the singular decomposition for UI decoupling, and then obtain the fault-related subsystem via controllability and observability decomposition. And then the multi-rate observer (MRO) with causality constraints is designed. Different from the traditional observer used for FD, the proposed MRO outputs the fault-related partial state estimate as soon as any a sensor measurement is received, resulting in fast and computation-effective FD. Furthermore, conditions for the existence of a stable MRO, fault-to-state controllability, and fault detectability are explored. A simulation example for simplified longitudinal flight control system and method comparison with the existing multi-rate FD algorithms show the effectiveness of the proposed MRFD method.

Active fault-tolerant control strategy of large civil aircraft under elevator failures

Aircraft longitudinal control is the most important actuation system and its failures would lead to catastrophic accident of aircraft. 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, trimmable 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.

Coordinated Control of Autonomous Four Wheel Drive Electric Vehicles for Platooning and Trajectory Tracking Using a Hierarchical Architecture

This paper presents a systematic method on how to design the coordinated lateral and longitudinal motion control system of autonomous four wheel drive (4WD) electric vehicles for platooning and trajectory tracking. First, mathematical models that perfectly describe the behaviors of autonomous 4WD vehicles are built-up, and the coupled effects in vehicle dynamic systems are given. Second, owing to the fact that autonomous vehicles are large-scale systems with strong coupling, nonlinearities, and uncertainties, a novel multi-objective hierarchical architecture used for coordinated lateral and longitudinal motion control is constructed, which is composed of a global cooperative control layer, a control allocation layer, and an action execution layer. A robust backstepping sliding mode controller (RBSMC) is presented in the cooperative control layer to provide the resultant forces/moment. The control allocation layer is designed using interior-point (IP) algorithm to determine the tire lateral and longitudinal forces, which result in the desired resultant forces/moment. The action execution layer consists of an inverse tire model, a slip ratio regulator for each wheel, and a slip angle regulator. Finally, simulation experiments are carried out under adverse driving conditions, and the results show that the proposed control architecture not only possesses excellent tracking performance but also enhances the riding comfort, stability, and safety of autonomous 4WD electric vehicles.

A UAV Longitudinal Control System Design Based on QFT

In this paper, the basic principle and design procedure of the quantitative feedback theory (QFT) are summarized, then control system of a UAV is designed with the QFT theory. The QFT theory can solve the robust design problem of the UAV control system due to the model parameters uncertainty perfectly. And a method of robust design for UAV is put forward from engineering application perspective. Compared with traditional control method, the simulation result shows that the control system designed by the QFT theory not only has more perfect control effect but has significant value in the engineering application.

Numerical study on the impact of gradient on semi-transverse smoke control system in tunnel

The impact of gradient in tunnels with longitudinal smoke control system has been studied extensively in the last two decades. However, the impact of gradient in tunnels with semi-transverse smoke control has long been neglected. In this paper, numerical simulations have been conducted to investigate the impact of gradient on the performance of semi-transverse smoke control system in a 500m long and rectangular tunnel. Firstly, tentative simulations are conducted in the horizontal tunnel until the adopted smoke control system can maintain the smoke layer well above the driveway for 30min and this scenario is then adopted as a benchmark. Secondly, the gradient of the tunnel is increased from 0% to 1% and the simulation shows that the buoyancy drives more smoke moving in the ascending direction, which gradually changes the flow pattern in the tunnel. Further increase the gradient to 3% and 5%, the smoke movement pattern changes more rapidly and makes the ascending section impassable for evacuation. To provide tenable conditions, the smoke extraction rates in tunnel with a gradient of 1–5% should be increased by 5–20% compared those in the horizontal tunnel.

Longitudinal vehicle dynamics control for improved vehicle safety

The aim is to investigate the improvements in vehicle safety that can be achieved by limiting the vehicle speed based on GPS path information. The control strategy is aimed at reducing vehicle speed before a potentially dangerous situation is reached, in contrast with widely used stability control systems that only react once loss of control by the driver is imminent. An MSC.ADAMS/View simulation model of an off-road test vehicle was developed and validated experimentally. A longitudinal speed control system was developed by generating a reference speed based on the path information. This reference speed was formulated by taking into account the vehicle’s limits due to lateral acceleration, combined lateral and longitudinal acceleration and the vehicle’s performance capabilities. The model was used to evaluate the performance of the control system on various tracks. The control system was implemented on the test vehicle and the performance was evaluated by conducting field tests. Results of the field tests indicated that the control system limited the acceleration vector of the vehicle’s centre of gravity to prescribed limits, as predicted by the simulations, thereby decreasing the possibility of accidents caused by rollover or loss of directional control due to entering curves at inappropriately high speeds.

A fault diagnosis based reconfigurable longitudinal control system for managing loss of air data sensors for a civil aircraft

An integrated fault diagnosis based fault tolerant longitudinal control system architecture is proposed for civil aircraft which can accommodate partial or total losses of angle of attack and/or calibrated airspeed sensors. A triplex sensor redundancy is assumed for the normal operation of the aircraft using a gain scheduled longitudinal normal control law. The fault isolation functionality is provided by a bank of 6 fault detection filters, which individually monitor each of the 6 sensors using robust low order LPV residual generators. In the case of losses of up to 5 sensors, a fault estimation technique based on LPV estimators can be employed to reconstruct the missing sensor information necessary for gain scheduling. In the worst case of a total failure of all 6 sensors, a robust constant longitudinal control law is employed which ensures a basic longitudinal control performance. The proposed control architecture fulfils the basic requirements formulated in the Benchmark Problem in the RECONFIGURE project.

Study on a longitudinal control and guidance system for lane change assistance

This paper presents a driver assistance system of lane change manoeuvre on highway. The assistance system is designed based on a reference driver model which employs common on-board vehicle sensing signals and determines the initiation timing and the magnitude of longitudinal and lateral accelerations. The assistance system is designed to be able to accelerate automatically in longitudinal direction and provide a beep sound to cue the initiation timing of steering manoeuvre by considering the human reaction time. The feasibility of the proposed assistance system is tested on a Driving Simulator (DS). The experimental scenarios are indicated in detail and the obtained results are statistically analysed from the individual and overall aspects of the conducted experiments.

Full-Scale Experiment of Longitudinal Ventilation Smoke Control System and Central Smoke Exhaust System in City Underwater Tunnel

Abstract Taking a city underwater tunnel as an example, temperature variation and smoke movement under longitudinal ventilation smoke control system and central smoke exhaust system were measured by full-scale experiment. Different longitudinal airflow speeds under central exhaust system were discussed. Based on the results, a fire caused by an accidental vehicular(3MW), longitudinal ventilation smoke control system accelerate the smoke spread to the downstream and the smoke sedimentation, increase smoke spread distance and decrease the temperature in tunnel. For central smoke exhaust system, smoke is being exhaust through the duct, reduces the speed of fire smoke movement and smoke sedimentation. But the temperature of central smoke exhaust system is higher than using longitudinal ventilation system at the downstream of tunnel.

A robust longitudinal sliding-mode controller design for autonomous ground vehicle based on fuzzy logic

This paper describes the development of a robust longitudinal controller for autonomous ground vehicle with inherent unknown nonlinearities and parametric uncertainties. The longitudinal controller is designed using Sliding-Mode Control (SMC) strategy based on fuzzy logic, which works through switching between the throttle actuator and brake actuator according to a predetermined criterion. The proposed longitudinal controller not only eliminates the chattering phenomenon in the Sliding-Mode Control (SMC) but also copes with the system uncertainties and external disturbances. Additionally, the convergence of closed-loop longitudinal control system is proved by the Lyapunov stability theory. Finally, simulation and experimental results indicate the strong robustness and commendable tracking performance of proposed controller.

Research on Vehicle Longitudinal Following Control Modeling and Collaborative Simulation

The vehicle longitudinal following control system has been widely used in several intelligent-vehicle applications as a kind of assist automatic driving system. On basic of general introduction and analysis of existing vehicle dynamics models, the paper choose vehicle power train model as an example to show the choice of control system structure and PID control strategy, and then researched the collaborative simulation based on driver safety distance model and entire vehicle following model for freeway. So we got an adaptive safety distance through Matlab/Simulink, which distance error is less than 0.01m. At the end, this paper putted forward prospect of vehicle assist automatic driving system.

LiDAR 기반 차량-인프라 연계 상황인지를 통한 사고다발지역에서의 차량 종방향 능동제어 시스템 연구

This is a research of an adaptive longitudinal control system for situated cognition in wide range, traffic accidents reduction and safety driving environment by integrated system which graft a road infrastructure's information based on IT onto the intelligent vehicle combined automobile and IT technology. The road infrastructure installed by laser scanner in intersection, speed limited area and sharp curve area where is many risk of traffic accident. The road infra conducts objects recognition, segmentation, and tracking for determining dangerous situation and communicates real-time information by Ethernet with vehicle. Also, the data which transmitted from infrastructure supports safety driving by integrated with laser scanner's data on vehicle bumper.

Nature Inspired Based Pitch Controller Design of an UAV

In this paper a longitudinal control system has been designed for a 2 Kg payload Unmanned Aerial Vehicle using classical PID controller. To overcome the difficulty in tuning the PID gains to the required values, different nature inspired techniques have been used, for the Integral Squared Error (ISE) parameter optimization on UAV dynamic data at a specified trim condition. For this purpose, the penalty function that has been chosen includes time domain specifications as constraints. Finally all the results are compared for optimum PID parameters.

Evolutionary design of a full-envelope full-authority flight control system for an unstable high-performance aircraft

The use of an evolutionary algorithm in the framework of H∞ control theory is being considered as a means for synthesizing controller gains that minimize a weighted combination of the infinite norm of the sensitivity function (for disturbance attenuation requirements) and complementary sensitivity function (for robust stability requirements) at the same time. The case study deals with a complete full-authority longitudinal control system for an unstable high-performance jet aircraft featuring (i) a stability and control augmentation system and (ii) autopilot functions (speed and altitude hold). Constraints on closed-loop response are enforced, that representing typical requirements on airplane handling qualities, that makes the control law synthesis process more demanding. Gain scheduling is required, in order to obtain satisfactory performance over the whole flight envelope, so that the synthesis is performed at different reference trim conditions, for several values of the dynamic pressure, used as the scheduling parameter. Nonetheless, the dynamic behaviour of the aircraft may exhibit significant variations when flying at different altitudes, even for the same value of the dynamic pressure, so that a trade-off is required between different feasible controllers synthesized at different altitudes for a given equivalent airspeed. A multi-objective search is thus considered for the determination of the best suited solution to be introduced in the scheduling of the control law. The obtained results are then tested on a longitudinal non-linear model of the aircraft.

Multi-objective robust PID controller tuning using two lbests multi-objective particle swarm optimization

In this paper, two lbests multi-objective particle swarm optimization (2LB-MOPSO) is applied to design multi-objective robust Proportional-integral-derivative (PID) controllers for two MIMO systems, namely, distillation column plant and longitudinal control system of the super maneuverable F18/HARV fighter aircraft. Multi-objective robust PID controller design problem is formulated by minimizing integral squared error (ISE) and balanced robust performance criteria. During the search, 2LB-MOPSO can focus on small regions in the parameter space in the vicinity of the best existing fronts. As the lbests are chosen from the top fronts in a non-domination sorted external archive of reasonably large size, the offspring obtained can be more diverse with good fitness. The performance of various optimal PID controllers is compared in terms of the sum of ISE and balanced robust performance criteria. For the purpose of comparison, 2LB-MOPSO, NSGA-II as well as earlier reported Riccati, IGA and OSA methods are considered. The performance of PID controllers obtained using 2LB-MOPSO is better than that of others. In addition, Hypervolume-based comparisons are carried out to show the superior performance of 2LB-MOPSO over NSGA-II. The results reveal that 2LB-MOPSO yields better robustness and consistency in terms of the sum of ISE and balanced robust performance criteria than various optimal PID controllers.

An Anthropomimetic Approach to High Performance Traction Control

Abstract The ability to learn and adapt to changing environmental conditions, as well as develop perceptive models based on stimulus-response data, provides expert human drivers with significant advantages. When it comes to bandwidth, accuracy, and repeatability, automatic control systems have clear advantages over humans; however, most high performance control systems lack many of the unique abilities of a human expert. This paper documents our first step toward the development of a novel automatic traction control algorithm using an anthropomimetic approach. The primary objective of this approach was to synthesize a high performance longitudinal traction control system by incorporating desirable human behavior distilled from human-in-the-loop (HIL) testing on a 6-DOF driving simulator. The proposed control algorithm was developed in a general framework, and applied to the specific task of longitudinal traction control. Simulation results confirm that the proposed anthropomimetic traction control algorithm provides improved performance relative to a well-tuned conventional PID-based traction control algorithm. Results are also compared with the HIL response data from a behavioral study.

Research on Robust Control of Longitudinal Motion of SWATH

Taking the uncertainty of SWATH longitudinal motion control system into account, the parameter uncertainty model of SWATH was built, and the -synthesis controller was designed to improve the longitudinal motion performance of SWATH. Then Matlab was utilized to simulate the controlled as well as uncontrolled longitudinal performance of SWATH. According to the simulation result, under different sailing conditions, the longitudinal motion performance of SWATH is still excellent. Therefore, the parameter uncertainty mathematical model built in this paper as well as the designed -synthesis controller are effective and applicable to improve the longitudinal motion performance and the robust performance of SWATH, providing the theoretical basis for the research on SWATH with high performance.