Helicopter Attitude Research Articles

Coaxial Helicopter Attitude Control System Design by Advanced Model Predictive Control under Disturbance

This paper proposes an advanced model predictive control (MPC) scheme for the attitude tracking of coaxial drones under wind disturbances. Unlike most existing MPC setups, this scheme embeds steady-input, steady-output, and steady-state conditions into the optimization problem as decision variables. Consequently, the coaxial drone’s attitude can slide along the state manifold composed of a series of steady states. This allows it to move toward the optimal reachable equilibrium. To address disturbances that are difficult to accurately measure, an extended state observer is employed to estimate the disturbances in the prediction model. This design ensures that the algorithm maintains recursive stability even in the presence of disturbances. Finally, numerical simulations and flight tests are provided to confirm the effectiveness of the proposed method through comparison with other control algorithms.

Adaptive-Neural Finite-Time Sliding Mode Control for Quadrotor Helicopter Attitude Stabilization in Complex Environments

Adaptive-Neural Finite-Time Sliding Mode Control for Quadrotor Helicopter Attitude Stabilization in Complex Environments

Flight Tracking Control for Helicopter Attitude and Altitude Systems Using Output Feedback Method under Full State Constraints

In this paper, we propose an output feedback flight tracking control scheme for helicopter attitude and altitude systems with unmeasured states under full state constraints. Firstly, a state observer is constructed based on the measured output signals, which is proven to be rigorous since all states are constrained within the desired and assigned scopes. Secondly, the flight tracking controller is built using the state estimations with the full state constraints control method. Then, the Barrier Lyapunov function method is adopted to guarantee the stability of the composite closed-loop nonlinear error systems. Meanwhile, the linear matrix inequality technology is applied to calculate the gains of the state observer. Finally, a numerical simulation example is provided to confirm the reasonableness of the full state constraint output feedback flight tracking control method.

Research on attitude control strategy of unmanned helicopter based on hybrid particle swarm optimization algorithm

For the unmanned helicopter attitude control problem, an optimal control strategy based on hybrid particle swarm optimization (PSO) algorithm has been proposed. Firstly, a coupled dynamics model of the system has been established based on the structural characteristics of the unmanned helicopter system; secondly, a gain scheduling control method has been adopted to select multiple system stable operating points with real-time error as the scheduling variable, and a gain scheduling attitude controller has been designed; further, the inertia weights and learning factors are dynamically adjusted on the basis of the traditional PSO algorithm, and a hybrid PSO algorithm has been proposed for unmanned helicopter attitude control; finally, the improved controller has been compared and verified by the semi-physical. The experimental results show that the improved algorithm improves the attitude control effect and anti-interference capability of the unmanned helicopter, resulting in a reduction of the adjustment time by about 3.8s and the maximum steady-state amplitude by about 0.154°.

Design of Quad-rotor Controller Based on Fractional Order Sliding Mode Control

According to the chattering problems of traditional sliding mode index exponential reaching law, this paper proposes a fractional order sliding mode index exponential reaching law control strategy, which is applied to the quad-rotor helicopter attitude control. Combined the theory of fractional order calculus and sliding mode variable structure control theory, the fractional order sliding mode controller is designed. The method of lyapunov analysis proves that this controller can make the system asymptotically stable. Simulation and experiments show that the proposed fractional order sliding mode control system not only undermines the chattering of traditional sliding mode exponential reaching law but also reduces the adjusting time and control margin of the system.

Anti-disturbance control for attitude and altitude systems of the helicopter under random disturbances

In this paper, the issue of anti-disturbance control is investigated for the helicopter attitude and altitude systems with multiple random disturbances. The disturbances are divided into two parts: one is described by the switching systems with Markovian jump parameters; the other one is from the random modeling noise, and considered as random perturbations in the controller design. Combining the disturbance observer based control method, the backstepping control approach and the stochastic Markovian jump system control theory, a flight controller is constructed to guarantee that the attitude and altitude helicopter systems track the predefine attitude and altitude within reasonable bounds. Finally, simulations are given to show the effectiveness of the proposed method.

Training a model-free reinforcement learning controller for a 3-degree-of-freedom helicopter under multiple constraints

The purpose of the article is to design data-driven attitude controllers for a 3-degree-of-freedom experimental helicopter under multiple constraints. Controllers were updated by utilizing the reinforcement learning technique. The 3-degree-of-freedom helicopter platform is an approximation to a practical helicopter attitude control system, which includes realistic features such as complicated dynamics, coupling and uncertainties. The method in this paper first describes the training environment, which consists of user-defined constraints and performance expectations by using a reward function module. Then, actor–critic-based controllers were designed for helicopter elevation and pitch axis. Next, the policy gradient method, which is an important branch of the reinforcement learning algorithms, is utilized to train the networks and optimize controllers. Finally, from experimental results acquired by the 3-degree-of-freedom helicopter platform, the advantages of the proposed method are illustrated by satisfying multiple control constraints.

Fault Estimation and Accommodation for a Class of Nonlinear System Based on Neural Network Observer

The problem of fault estimation and accommodation of nonlinear systems with disturbances is studied using adaptive observer and neural network techniques. A robust adaptive learning algorithm based on switching βs-modification is developed to realize the accurate and fast estimation of unknown actuator faults or component faults. Then a fault tolerant controller is designed to restore system performance. Dynamic error convergence and system stability can be guaranteed by Lyapunov stability theory. Finally, simulation results of quadrotor helicopter attitude systems are presented to illustrate the efficiency of the proposed techniques.

Control Method for Helicopters Tethered to Ground Station with Compensation for Disturbance Caused by Cable Tension

This paper proposes cable tension compensation control method for helicopters cabled to a ground station. This method can be applied to human-operated systems and reduces the required control skill. The cable tension vector is measured by a force sensor and an angle sensor mounted to the helicopter. Thrust and helicopter attitude to balance with resultant force of tension and gravity are calculated and automatically added to attitude controller input calculated by using PID control. Simulation and experimental results demonstrate the validity of the proposed method.

Incipient Fault Detection Using an Associated Adaptive and Sliding-Mode Observer for Quadrotor Helicopter Attitude Control Systems

An associated adaptive and sliding-mode observer (AASMO) design is proposed to detect and estimate the incipient actuator faults of a quadrotor. The incipient faults considered are physical structure aging and quadrotor leakage. First, disturbances and nonlinear parameters are considered in system formulation for a realistic mathematical model of the quadrotor. Its fault model is also introduced. Second, the decomposed subsystems are obtained through coordinate transformations to separate the incipient faults from the disturbances. For the subsystem with no disturbance, the adaptive observer can estimate the incipient faults. For the subsystem with disturbances, the sliding-mode observer has strong robustness against the disturbances. Dynamic error convergence and system stability can also be guaranteed by Lyapunov stability theory. Finally, the simulation results of quadrotor helicopter attitude systems validate the efficiency of the proposed AASMO-based incipient fault detection algorithm.

地上局とケーブルでつながれたヘリコプターの3次元張力補償制御

This paper suggests cable tension compensation control for helicopters cabled to the ground station. This method can be applied to human operated system and reduces required skill. In this method, three-dimensional cable tension vector is measured by a force sensor and an angle sensor mounted on the helicopter. Thrust and helicopter attitude to balance with resultant force of the tension and the gravity force are calculated and added to control input by PID control. Experimental result illustrate validity of the proposed method

LADRC-based attitude decoupling control for helicopter and parameters tuning

To meet the ADS-33E-PRF flight quality and effectively overcome the influence of external disturbance,an attitude control strategy based on a linear active disturbance rejection control( LADRC) is proposed for helicopter. Flight dynamics model of UH-60 A and the wind model were established. UH-60 A was trimmed for verifying accuracy of dynamic model and trim algorithm. Helicopter attitude decoupling control loop based on the single input / single output second-order LADRC controller was set up with stabilization feedback loop. The controller parameter tuning problem was transformed into constrained optimization problem in time and frequency domain according to quality requirement of ADS-33E-PRF. Combining H-infinity synthesis algorithm and steepest descent algorithm,the optimization of parameters was calculated. Quality assessment of attitude control was made and the control loop was applied to the attitude hold control simulation in atmospheric disturbance. The results of simulation and quality evaluation show that the attitude control system based on LADRC has good decoupling performance and capability of anti-disturbance.

Robust backstepping decentralized tracking control for a 3-DOF helicopter

A three-degree-of-freedom helicopter attitude tracking control system can be described as a multi-input multi-output strict-feedback form system with unknown parameters, bounded disturbances, and nonlinear uncertain cross-couplings. Both norm-bounded and nonlinear uncertainties are discussed. The whole nonlinear system is divided into a nominal disturbance-free system and an equivalent disturbance part. A robust control method based on signal compensation technique and backstepping decentralized control is proposed. Robust practical tracking property of closed-loop system is proven, and the tracking error can be made as small as desired with expected convergence rate. Experimental results demonstrate the improved tracking performance of the attitude tracking control system with different types of reference signals, such as step signals, ramp signals, and nonstationary sinusoidal signals.

Mechanism of intermittent failures in extreme vibration environment and online diagnosis technology

The intermittent faults induced by environment stress such as extreme vibration have deep impact on the serviceability and reliability of equipment. In this paper, the term of the extreme vibration environment is defined. The finite element simulation model of the component is established, and the mechanism and laws that how the extreme vibration environmental stress induces intermittent faults are analyzed. Based on the elastic-plastic stress theory, a method of calculating component’s cumulative damage in extreme vibration environment is proposed. Then a hidden Markov model (HMM) based Tri-State (normal state, intermittent state and fault state) injury correlation model is built. Starting with the relationship analysing between the features in each state of components and the interior cumulative damage, the cumulative damage based HMM model for intermittent fault diagnosis is established. After that, a real-time fault diagnosis method is proposed. Tests are carried out on a helicopter attitude indicator in extreme vibration environment. The test results show that the occurrence probability of intermittent fault becomes large with the increase of the vibration magnitude and time. The proposed fault diagnosis method can detect the intermittent fault efficiently.

Adaptive compensation control of the quadrotor helicopter using quantum information technology and disturbance observer

In this paper, an adaptive compensation control scheme is developed via disturbance observer and quantum information technology for the four-rotor helicopter, which can handle the control problems of helicopter's attitude with the unknown actuator failures and external disturbance effectively. Both the digital simulations and the semi-physical simulations in a Quanser 3-DOF hover platform illustrate the effectiveness of the proposed compensation control scheme.

Helicopter Harsh Landing Events: A Computational Hybrid Methodology to Estimate Fuselage Damage

A landing that exceeds design conditions is usually referred to as a hard or harsh landing. This condition is delimited between the usual operational conditions and the crash event. Helicopter structural damage due to harsh landings is generally not as severe as during a crash, but it may lead to unscheduled maintenance events, involving costs and idle time. The aim of the current paper is to define a methodology, which estimates (by means of hybrid, multi-environment analyses) the damage state of a part of a helicopter fuselage after a harsh landing event. In particular, a mixed multibody finite element modeling strategy is used to achieve computationally efficient results, which are obtained for various landing conditions, in terms of drop heights and the helicopter attitude at landing. The obtained model may be useful both in a design scenario and in exploring structural health monitoring applications. With the latter in mind, output data were deeply investigated with a dedicated focus on the correlation between the damage position and landing conditions. Stringers in a particular zone of the fuselage were identified as the most affected zone (by localized plasticization) during harsh landings. This result provides a possible basis for using focused structural health monitoring strategies. With this in mind, a zone selection criterion, as a tradeoff between sensorization extension and performance, was proposed.

Helicopter Maneuver Flight Simulation and Control Law Design

This paper presents a solution to helicopter maneuver flight simulation according to ADS33 flying qualities requirement standard. Associated with aerodynamics and control law design methodology, the proposed scheme achieved satisfactory control performance by analyzing helicopter attitude and control parameter variation law at certain operating condition. To level flight acceleration, method based on force and moment balance is analyzed. To pirouette maneuver, a segment linear approximated trajectory is developed for attitude and velocity stability. All objective function is based on minimizing position error and attitude error. For a single rotor four bladed model helicopter in pirouette maneuver, experimental results certified its efficiency.

PID Gain Tuning for Disturbance Attenuation FRIT Method

This review paper shows a PID gains tuning method from one-shot experimental data generated by test signal added at input signal in an off-line manner, so that the output signal could follow the prescribed reference model output. We call the method a “disturbance attenuation FRIT method” because the test signal added at input signal is a benchmark signal evaluating disturbance attenuation property. The experimental result for helicopter attitude control model is demonstrated to show the effectiveness of the disturbance attenuation FRIT method.

PID controller tuning based on disturbance attenuation FRIT using one-shot experimental data due to a load change disturbance

A direct design approaches based on input-output measurements with no need for help from a plant model have attracted attention from several researchers. We have recently proposed such a disturbance attenuation FRIT method using input-output data generated by disturbances. The approach has advantages that it can tune PID gains to improve feedback properties, such as disturbance attenuation. Furthermore, the method has been applied to PID control gain tuning. The method tunes PID gains using one-shot experimental data generated by a known step-type disturbance added at the input signal. However, additive known step-type signal implies a test signal to identify the characteristic of the control systems, so the case where the method can be applied may be restricted. The paper, therefore, gives a tuning method using a one-shot experimental data generated by a load change. Such a disturbance has a possibility that the data can be collected during a full operation. The proposed method can be realized by estimating the magnitude of an impulse and step signal for a load change disturbance from one-shot experimental data. The proposed method realizes the approach by modeling a load change disturbance as a linear combination of a step signal and an impulse signal, where the weighting parameters are unknown. The paper also gives the way how unknown parameters are estimated from the one-shot initial input-output data. Finally, this paper shows the efficiency of the disturbance attenuation FRIT through the experimental result of a helicopter attitude control model when the disturbance is known or correctly estimated.

Design of Longitudinal Optimal Controller in Unmanned Helicopter Based on Genetic Algorithm

In this paper, the main research direction of optimal control is aimed at mathematical model of small unmanned helicopter longitudinal channels. Genetic algorithm was used to optimize the select of control law which is tolerance, make small unmanned helicopter operate as given requirements, and make the given performance index achieve optimal value (minimum or maximum). This paper will introduce the optimal control theory to attitude control system of small unmanned helicopter. The simulation results prove that this method can well satisfy the control accuracy requirement of small unmanned helicopter attitude system.