Attitude Controller Design Research Articles

Linear parameter varying switching attitude control for a near space hypersonic vehicle with parametric uncertainties

This paper deals with the problem of linear parameter varying (LPV) switching attitude control for a near space hypersonic vehicle (NSHV) with parametric uncertainties. First, due to the enormous complexity of the NSHV nonlinear attitude dynamics, a slow–fast loop polytopic LPV attitude model is developed by using Jacobian linearisation and the tensor product model transformation approach. Second, for the purpose of less conservative attitude controller design, the flight envelope is divided into four subregions. For each parameter subregion, slow-loop and fast-loop LPV controllers are designed. By the defined switching character function, these slow–fast loop LPV controllers are then switched in order to guarantee the closed-loop NSHV system to be asymptotically stable and satisfy a specified tracking performance criterion. The condition of LPV switching attitude controller synthesis is given in terms of linear matrix inequalities, which can be readily solved via standard numerical software, and the robust stability analysis of the closed-loop NSHV system is verified based on multiple Lypapunov functions. Finally, numerical simulations have demonstrated the effectiveness of the proposed approach.

Application of Optimization technique for Compensator design of Launcher Attitude Control

This paper deals with the compensator design of launch vehicle attitude control in atmospheric phase using optimization algorithm. Traditionally compensator design is carried out intuitively based on physical parameters of launch vehicle. It is arrived at after a long trial and error procedure to fulfil frequency domain requirements. In this paper a multi-constraint satisfaction algorithm is used to design compensator for attitude control, which takes into account the frequency and time domain requirements. The effect of actuator non-linear behavior on slosh dynamics is investigated and the analytical expression for slosh response with respect to actuator amplitude is derived. The slosh closed loop pole migration with the variation in actuator command amplitudes in root locus is discussed and the implication of acceptable actuator limit cycle amplitude on vehicle body rate is brought out.

Parameter Identification and Attitude Control of Ducted Fan UAVs

For UAVs are favored by many countries, the reason is that they are not affected by man-induced factor. While the ducted fan UAV is a new type of UAV, rises in recent years, but it has become very hot in the field of the research and development of miniature unmanned aerial vehicle. This paper is based on the research of a kind of small ducted fan UAVs, and works on the system parameter identification of the UAV and the design of attitude controller.

Robust Two-Degrees-of-Freedom Attitude Controller Design and Flight Test Result for Engineering Test Satellite-VIII Spacecraft

This paper reports flight test results of robust attitude control for the Engineering Test Satellite VIII (ETS-VIII) spacecraft. The main mission of ETS-VIII is to support next-generation mobile digital communications, and for this purpose it is equipped with two large deployable antenna reflectors and a pair of large solar panels that rotate around the pitch axis. We have proposed and demonstrated several control methods for this spacecraft based on advanced control theories for linear parameter varying multi-input multi-output systems, and in this paper we focus on a two-degrees-of-freedom controller. We describe the controller design methods and present the results of on-orbit flight tests. The controller's superiority is demonstrated by comparing its performance with other controllers.

Discoid and Asymmetrical Micro-Satellite Propulsion Mode Attitude Control with Great Mass Change and without Angular Rate Sensor

The center of mass of the micro-satellite can offset due to fuel consumption in the course of propulsion, with the interference of external orbital environment such as gravity gradient torque and solar radiation torque. If the structural shape is discoid and asymmetrical, the attitude control may be difficult. The only solution is to design a robust controller, so that the attitude pointing of the satellite can meet the mission requirements with the interference of internal parameter perturbation and external disturbance. This study applied the robust control theory control law in the design of Formosat-3 propulsion mode attitude control, and carried out cross validation of the feasibility of the controller by time domain and frequency domain stability analyses. This study used controller as the experimental result. The time domain performance indexes (e.g., rise time, maximum overshoot and stabilization time) of the designed controller were consistent with the robust stability margin of stable performance index of frequency domain. Meanwhile, in order to reduce the weight and manufacturing cost of satellite, in the design of satellite attitude angular rate determination, the project used unscented kalman filter (UKF) algorithm, coarse sun sensor (CSS) and earth horizon sensor (EHS) as measurement components to obtain the satellite attitude without rate gyro. The research method and procedures in this study are applicable to any shaped and asymmetrical satellites with large mass variation and without angular rate sensor. The attitude sensors include three-axis magnetometer, horizon sensor, CSS as the analytic platform for stability of attitude control.

IPMSM의 센서리스 운전을 위한 확장 칼만 필터 설계

본 논문은 IPMSM(Interior Permanent Magnet Synchronous Motor)의 센서리스 운전을 위해 확장 칼만 필터를 기반으로 하는 속도와 위치 추정기의 설계방법을 제안한다. 제안된 방법은 상태 추정의 정밀도를 향상시키기 위해서 시스템 모델의 상태추정구간을 더욱 세분화하여 나누고, 세분화한 각 구간을 테일러급수 전개하여 일차항만 사용하여 추정하였다. 제안된 상태 추정기는 2차 확장칼만필터에 비해 사전추정의 연산의 양을 크게 하지 않고, 상태추정의 정밀도가 증가함을 시뮬레이션을 통해 보일 수 있었다. In this paper, a design of speed and position controller based on the EKF(Extended Kalman Filter) for sensorless control in IPMSM(Interior Permanent Magnet Synchronous Motor) is proposed. The proposed method subdivides the state estimation interval for improving the accuracy of state estimation. and each subdivided interval estimated first order term using Taylor series. The proposed state estimator comparison with the second-order extended Kalman filter reduced calculation amount of a priori estimation. And the simulation results were proved that The accuracy of priori estimation is increased.

Attitude Controller Design of Multiple Independently Targeted Reentry Vehicle Based on Internal Model Control

A Multiple Independently Targeted Reentry Vehicle (MIRV) is a ballistic missile payload containing several warheads each capable of hitting one of a group of targets. In the process of missile flight control, the release of warheads brings about coupling to the missile attitude control system which will lower the flight stability. In order to solve this problem, a missile attitude controller, which combined the α-order integral inverse system with internal model principle, was presented. Firstly, determine the Post Boost Vehicle (PBV) attitude dynamics model. Then, combine the linearization of attitude dynamics equation with feed-forward decoupling method to implement the attitude decoupling. Finally, a two-degree of freedom (TOF) multivariable internal model controller was set up to optimize the control system performance. Simulation results show that the coupling of attitude control system has been eliminated. Compared with the original system, the internal model controller provides the control system better input-tracking performance, robust stability and interference suppression capacity.

Genetic Algorithm (GA) Based Optimal Feedback Control Weighting Matrices Computation -ENG

Linear Quadratic Regulator (LQR) is one of the most interesting control techniques adopted as a control strategy in state feedback. These types of techniques achieve good results but suffer from the problem of trial and error involved in the computation of weight matrices. The trial and error technique leads to hard tuning of the LQR controller parameters. This of course will lead to difficulty in reaching the optimal system performance. The paper attempts to solve the above difficulty via the selection of the LQR weight matrices using Genetic Algorithm GA. This proposed solution will avoid the trail and error involved in the state feedback technique. The proposed solution has been adopted in the design of position controller of a robot arm and the results of computer simulation have shown that the proposed solution fulfill specifications, for minimum overshoot , settling and rising times. Keywords: Robot Arm,Linear Quadratic Regulator (LQR) Genetic Algorithm(GA)

Robust control of near-space vehicles with input backlash-like hysteresis

In this article, robust attitude control schemes are proposed for the near-space vehicle with the backlash-like hysteresis and the time-varying unknown disturbance using backstepping technique. In the robust attitude control design, the backlash-like hysteresis is described by a dynamic equation which is decomposed as a linear term and a nonlinear term. To handle the nonlinear term in the dynamic equation of the backlash-like hysteresis and the time-varying unknown disturbance, they are treated as a compounded disturbance and the nonlinear disturbance observer is designed to estimate them. Based on the developed nonlinear disturbance observer, the robust backstepping attitude control is firstly developed for the near-space vehicle. Then, the robust sliding mode attitude control scheme is presented for the near-space vehicle to further enhance the robust attitude control performance. The convergence of all closed-loop signals is rigorously proved via Lyapunov analysis method under the developed robust attitude control schemes. Finally, simulation results are presented to illustrate the effectiveness of the proposed attitude control approaches.

Reusable boosted vehicle attitude controller design

PurposeThe purpose of this paper is to develop an attitude control strategy for the reusable boosted vehicle with large angle of attack, and to remove the cross coupling among roll, pitch and yaw channels.Design/methodology/approachThe coordinated gain scheduling control strategy consists mainly of two parts. First, initially ignoring dynamic coupling, single channel gain scheduling controller is designed based on linearized models, respectively. Second, with respect to main channel gain scheduling controller, coordinated scheduling controller is used to generate intentionally cross coupling to partly cancel inter‐channel cross coupling of reusable boosted vehicle.FindingsA coordinated gain scheduling control strategy is presented, and no such analytical solution can be found for the reusable boosted vehicle.Practical implicationsThe design idea of coordinated gain scheduling strategy is straightforward in physical concepts and has great value for engineering applications.Originality/valueCoordinated gain scheduling control strategy is novel in that single channel gain scheduling design does not involve small perturbation linearization and coordinated channel is scheduled.

Control system design and evaluation for robust autonomous rotorcraft guidance

This paper describes the design and performance analysis of a control system for rotorcraft with an emphasis on the requirements called for by autonomous guidance. To be able to track trajectories, such as those generated by a guidance system, a path following controller is used in combination with a velocity control augmentation. The path following system is motivated by nonlinear stability analysis. The velocity control augmentation follows a loop-shaping design for the inner-loop attitude control and a dynamic inversion velocity control design for the outer-loop. The identified model of the dynamics along with the uncertainties is used to determine the robustness and performance of the velocity control system. Finally, the paper presents a novel method to evaluate the overall performance of the control system in terms of the tracking error statistics. These results are then used to determine a tracking error model, which can be used to predict the tracking error for a given reference.

Robust and optimal attitude control of spacecraft with disturbances

In this paper, a robust and optimal attitude control design that uses the Euler angles and angular velocities feedback is presented for regulation of spacecraft with disturbances. In the control design, it is assumed that the disturbance signal has the information of the system state. In addition, it is assumed that the disturbance signal tries to maximise the same performance index that the control input tries to minimise. After proposing a robust attitude control law that can stabilise the complete attitude motion of spacecraft with disturbances, the optimal attitude control problem of spacecraft is formulated as the optimal game-theoretic problem. Then it is shown that the proposed robust attitude control law is the optimal solution of the optimal game-theoretic problem. The stability of the closed-loop system for the proposed robust and optimal control law is proven by the LaSalle invariance principle. The theoretical results presented in this paper are illustrated by a numerical example.

Attitude controller for reentry vehicles using state-dependent Riccati equation method

To get better tracking performance of attitude command over the reentry phase of vehicles, the use of state-dependent Riccati equation (SDRE) method for attitude controller design of reentry vehicles was investigated. Guidance commands are generated based on optimal guidance law. SDRE control method employs factorization of the nonlinear dynamics into a state vector and state dependent matrix valued function. State-dependent coefficients are derived based on reentry motion equations in pitch and yaw channels. Unlike constant weighting matrix Q, elements of Q are set as the functions of state error so as to get satisfactory feedback and eliminate state error rapidly, then formulation of SDRE is realized. Riccati equation is solved real-timely with Schur algorithm. State feedback control law u(x) is derived with linear quadratic regulator (LQR) method. Simulation results show that SDRE controller steadily tracks attitude command, and impact point error of reentry vehicle is acceptable. Compared with PID controller, tracking performance of attitude command using SDRE controller is better with smaller control surface deflection. The attitude tracking error with SDRE controller is within 5°, and the control deflection is within 30°.

Radio Aurora Explorer: A Mission Overview

The primary objective of the Radio Aurora Explorer mission is to study plasma instabilities that lead to magnetic field aligned irregularities of electron density in the lower polar ionosphere (80–400 km). These irregularities are known to disrupt communication and navigation signals. The Radio Aurora Explorer mission uses a bistatic radar configuration; the spacecraft is the radar receiver and the transmitters are several worldwide incoherent scatter radars of which the primary radar is located in Poker Flat, Alaska. The satellites are 3 kg, university-class CubeSats with a primary payload of a direct-conversion radar receiver operating in the frequency range from 426 to 510 MHz. The satellite bus has a novel configuration of processing, attitude control, and antenna design that met the physical constraints of the CubeSat form factor and the one-year schedule constraint imposed by launch dates. Two satellites have launched: RAX-1 on 19 November 2010 onboard a Minotaur-IV rocket from Kodiak, Alaska, and RAX-2 on 28 October 2011 onboard a Delta-II rocket from Vandenberg U.S. Air Force Base, California. RAX-2 has detected and measured irregularities during multiple experiments over Alaska and Canada. Preliminary analysis indicates unprecedented characterization of the irregularities.

Robust attitude control design for spacecraft under assigned velocity and control constraints

A novel robust nonlinear control design under the constraints of assigned velocity and actuator torque is investigated for attitude stabilization of a rigid spacecraft. More specifically, a nonlinear feedback control is firstly developed by explicitly taking into account the constraints on individual angular velocity components as well as external disturbances. Considering further the actuator misalignments and magnitude deviation, a modified robust least-squares based control allocator is employed to deal with the problem of distributing the previously designed three-axis moments over the available actuators, in which the focus of this control allocation is to find the optimal control vector of actuators by minimizing the worst-case residual error using programming algorithms. The attitude control performance using the controller structure is evaluated through a numerical example.

Pitch Attitude Control Design of Unmanned Aerial Vehicle via Hardware-in-the-Loop Simulation

This paper describes an investigative hardware-in-the-loop simulation (HILS) effort through virtual instrumentation on longitudinal control of an unmanned aerial vehicle (UAV). The proportional-integral-differential (PID) controller and fuzzy logic controller (FLC) are designed for the pitch angle hold mode of autopilot; moreover, they are implemented by an embedded real-time control system as a prototype autopilot and tested by hardware-in-the-loop simulation. The hardware configuration of HILS is composed of a personal computer, an embedded real-time control system, several data acquisition devices, servo and sensor unit. The real-time control and data acquisition tasks in HILS is carried out by virtual instruments that is developed by graphical programming language LabVIEW. HILS provides a platform for researchers to correct and improve their design efficiently. The closed-loop performance between PID controller and FLC is evaluated in HILS. The results demonstrate that in the presence of unmodelled dynamics and nonlinear saturation the FLC has an excellent robust performance.

Attitude and Altitude Controller Design for Quad-Rotor Type MAVs

Micro air vehicles (MAVs) have a wide application such as the military reconnaissance, meteorological survey, environmental monitoring, and other aspects. In this paper, attitude and altitude control for Quad-Rotor type MAVs is discussed and analyzed. For the attitude control, a new method by using three gyroscopes and one triaxial accelerometer is proposed to estimate the attitude angle information. Then with the approximate linear model obtained by system identification, Model Reference Sliding Mode Control (MRSMC) technique is applied to enhance the robustness. In consideration of the relatively constant altitude model, a Linear Quadratic Gaussian (LQG) controller is adopted. The outdoor experimental results demonstrate the superior stability and robustness of the controllers.

Design of the Microsatellite Attitude Control System Using the Mixed Method via LMI Optimization

Due to the space missions limited budget, small satellite cluster or constellation would be an economical choice. From risk-sharing viewpoint, a number of smaller satellites have a significant reliability advantage over a bigger one. Generally, one satellite is subject to two types of uncertainties: structured uncertainty that represents some satellite parameter variation and the unstructured uncertainty that represents some kind of the satellite model error. On the other hand, the Satellite Attitude Control (SAC) design becomes more vulnerable to uncertainty disturbances like model error and moment-of-inertia variation as the satellite has great decrease in size and weight. This is the case for a microsatellite with mass less than 100 kg where the ACS performance and robustness become very sensitive to both kinds of uncertainties. As a result, the design of the SAC has to deal with both types of uncertainties which is associated with the drawback between controller performance and robustness. The purpose of this work is to model a microsatellite taking into account the uncertainties and to perform the Control System Design based on the mixed methodology via LMI optimization.

Operator Error Based Design of Position Controllers for Dynamically Slow Systems

Previous work has found that performance with position control exceeds that with rate control except for dynamically slow systems, such as hydraulic machines. In an effort to extend the intuitiveness of position control to these systems, a novel human-machine interface was applied to a dynamically slow system. This paper analyzes the cost in time and in control effort of the errors operators made while controlling the position of a dynamically slow system. From this analysis, two “smoothing” position controllers were designed and tested on the same system. The first controller, the best fit controller, showed significant improvement for tracking tasks and maintained the near optimal performance of the full state feedback position controller on point-to-point motion tasks. The second controller, the time elimination controller, showed statistically similar performance on all of the tasks to the full state feedback position controller.

Modeling and Robust Trajectory Tracking Control for a Novel Six-Rotor Unmanned Aerial Vehicle

Modeling and trajectory tracking control of a novel six-rotor unmanned aerial vehicle (UAV) is concerned to solve problems such as smaller payload capacity and lack of both hardware redundancy and anticrosswind capability for quad-rotor. The mathematical modeling for the six-rotor UAV is developed on the basis of the Newton-Euler formalism, and a second-order sliding-mode disturbance observer (SOSMDO) is proposed to reconstruct the disturbances of the rotational dynamics. In consideration of the under-actuated and strong coupling properties of the six-rotor UAV, a nested double loops trajectory tracking control strategy is adopted. In the outer loop, a position error PID controller is designed, of which the task is to compare the desired trajectory with real position of the six-rotor UAV and export the desired attitude angles to the inner loop. In the inner loop, a rapid-convergent nonlinear differentiator (RCND) is proposed to calculate the derivatives of the virtual control signal, instead of using the analytical differentiation, to avoid “differential expansion” in the procedure of the attitude controller design. Finally, the validity and effectiveness of the proposed technique are demonstrated by the simulation results.