PD-like finite time controller with simple structure for satellite attitude control

A finite time controller with PD-like structure for satellite attitude control is proposed in this paper.The controller is constructed with simple structure based on standard PD controller.The fractional order term is designed hence system could both have strong robustness and finite time convergence rate,and the advantage of finite time control and PD control is combined in this paper.System convergence rate is discussed by Lyapunov method,and the constraint on control parameters is given by implementing the coupled term of angular velocity and attitude quaternion.Moreover,the accuracy at steady stage depending on control parameters is given hence system could converge to this field within finite time.System stability and performance is demonstrated by numerical simulation results.

Bias Momentum Attitude Control System Using Energy/Momentum Wheels

The integrated power and attitude control for a bias momentum attitudecontrol system is investigated. A pair of counter-spinning wheels is used to provide the biasangular momentum and store/ discharge energy for power requirement of the devices on the spacecraft.The roll/yaw motion is controlled by pitch magnetic dipole moment. The torque-based control law ofthe wheels is designed, so that the desired pitch control torque is provided and the operation ofcharging/discharging energy is carried out based on the given power. System singularity in thecontrol law of wheels is fully avoided by keeping the wheels counter-spinning. A power managementscheme using kinetic energy feedback is proposed to keep energy balance, which can avoid wheelsaturation caused by superfluous energy. The minimum moment of inertia of the wheels is limited bythe maximum bias angular momentum and the minimum energy, such constrains are analyzed incombination with the geometrical method. Numerical simulation results are presented to demonstratethe effectiveness of the control scheme.

Integrated Power and Single Axis Attitude Control System with Two Flywheels

The existing research of the integrated power and attitude control system（IPACS） in satellites mainly focuses on the IPACS concept,which aims at solving the coupled problem between the attitude control and power tracking.In the IPACS,the configuration design of IPACS is usually not considered,and the coupled problem between two flywheels during the attitude control and energy storage has not been resolved.In this paper,an integrated power and single axis attitude control system using two counter rotating magnetically suspended flywheels mounted to an air table is designed.The control method of power and attitude control using flywheel is investigated and the coupling problem between energy storage and attitude control is resolved.A computer simulation of an integrated power and single axis attitude control system with two flywheels is performed,which consists of two counter rotating magnetically suspended flywheels mounted to an air rotary table.Both DC bus and a single axis attitude are the regulation goals.An attitude ＆ DC bus coordinator is put forward to separate DC bus regulation and attitude control problems.The simulation results of DC bus regulation and attitude control are presented respectively with a DC bus regulator and a simple PD attitude controller.The simulation results demonstrate that it is possible to integrate power and attitude control simultaneously for satellite using flywheels.The proposed research provides theory basis for design of the IPACS.

IMPROVED PARTICLE SWARM OPTIMIZATION ALGORITHM FOR INTELLIGENTLY SETTING UAV ATTITUDE CONTROLLER PARAMETERS

An improved particle swarm optimization （PSO） algorithm is investigated in the optimization of the attitude controller parameters of unmanned aerial vehicle （UAV）. Considering the stagnation phenomenon in the later phase of the basic PSO algorithm caused by the diversity scarcity of particles, a modified PSO algorithm is presented. For the basic PSO algorithm, the velocity of each particle is adjusted according to the inertia motion, the swarm previous best position and its own previous best position. However, in the improved PSO algorithm, each particle only learns from another randomly selected particle with higher performance, besides keeping the inertia motion. The inertia weight of the improved PSO algorithm is a random number. The modification decreases the uncertain parameters of the algorithm, simplifies the learning mechanism of the particle, and enhances the diversity of the swarm. Furthermore, a UAV attitude control system is built, and the improved PSO algorithm is applied in the optimized tuning of four controller parameters. Simulation results show that the improved PSO algorithm has stronger global searching ability than the common PSO algorithms, and obtains better UAV attitude control parameters.

A Novel Robust Attitude Control for Quadrotor Aircraft Subject to Actuator Faults and Wind Gusts

A novel robust fault tolerant controller is developed for the problem of attitude control of a quadrotor aircraft in the presence of actuator faults and wind gusts in this paper.Firstly, a dynamical system of the quadrotor taking into account aerodynamical effects induced by lateral wind and actuator faults is considered using the Newton-Euler approach. Then,based on active disturbance rejection control(ADRC), the fault tolerant controller is proposed to recover faulty system and reject perturbations. The developed controller takes wind gusts,actuator faults and measurement noises as total perturbations which are estimated by improved extended state observer(ESO)and compensated by nonlinear feedback control law. So, the developed robust fault tolerant controller can successfully accomplish the tracking of the desired output values. Finally, some simulation studies are given to illustrate the effectiveness of fault recovery of the proposed scheme and also its ability to attenuate external disturbances that are introduced from environmental causes such as wind gusts and measurement noises.

High-order sliding mode attitude controller design for reentry flight

A novel high-order sliding mode control strategy is proposed for the attitude control problem of reentry vehicles in the presence of parametric uncertainties and external disturbances, which results in the robust and accurate tracking of the aerodynamic angle commands with the finite time convergence. The proposed control strategy is developed on the basis of integral sliding mode philosophy, which combines conventional sliding mode control and a linear quadratic regulator over a finite time interval with a free-final-state and allows the finite-time establishment of a high-order sliding mode. Firstly, a second-order sliding mode attitude controller is designed in the proposed high-order siding mode control framework. Then, to address the control chattering problem, a virtual control is introduced in the control design and hence a third-order sliding mode attitude controller is developed, leading to the chattering reduction as well as the control accuracy improvement. Finally, simulation examples are given to illustrate the effectiveness of the theoretical results.

Robust Attitude Control for Reusable Launch Vehicles Based on Fractional Calculus and Pigeon-inspired Optimization

In this paper, a robust attitude control system based on fractional order sliding mode control and dynamic inversion approach is presented for the reusable launch vehicle RLV during the reentry phase. By introducing the fractional order sliding surface to replace the integer order one, we design robust outer loop controller to compensate the error introduced by inner loop controller designed by dynamic inversion approach. To take the uncertainties of aerodynamic parameters into account, stochastic robustness design approach based on the Monte Carlo simulation and Pigeon-inspired optimization is established to increase the robustness of the controller. Some simulation results are given out which indicate the reliability and effectiveness of the attitude control system. © 2014 Chinese Association of Automation.

Attitude Control of Multiple Rigid Bodies with Uncertainties and Disturbances

Decentralized attitude synchronization and tracking control for multiple rigid bodies are investigated in this paper. In the presence of inertia uncertainties and environmental disturbances, we propose a class of decentralized adaptive sliding mode control laws. An adaptive control strategy is adopted to reject the uncertainties and disturbances. Using the Lyapunov approach and graph theory, it is shown that the control laws can guarantee a group of rigid bodies to track the desired time-varying attitude and angular velocity while maintaining attitude synchronization with other rigid bodies in the formation. Simulation examples are provided to illustrate the feasibility and advantage of the control algorithm. © 2014 Chinese Association of Automation.

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°.

Concept Design,Modeling and Station-keeping Attitude Control of an Earth Observation Platform

The stratosphere airship provides a unique and promising platform for earth observation. Researches on the project design and control scheme for earth observation platforms are still rarely documented. Nonlinear dynamics, model uncertainties, and external disturbances contribute to the difficulty in maneuvering the stratosphere airship. A key technical challenge for the earth observation platform is station keeping, or the ability to remain fixed over a geo-location. This paper investigates the conceptual design, modeling and station-keeping attitude control of the near-space earth observation platform. A conceptual design of the earth observation platform is presented. The dynamics model of the platform is derived from the Newton-Euler formulation, and the station-keeping control system of the platform is formulated. The station-keeping attitude control approach for the platform is proposed. The multi-input multi-output nonlinear control system is decoupled into three single-input single-output linear subsystems via feedback linearization, the attitude controller design is carried out on the new linear systems using terminal sliding mode control, and the global stability of the closed-loop system is proven by using the Lyapunov theorem. The performance of the designed control system is simulated by using the variable step Runge-Kutta integrator. Simulation results show that the control system tracks the commanded attitude with an error of zero, which verify the effectiveness and robustness of the designed control system in the presence of parametric uncertainties. The near-space earth observation platform has several advantages over satellites, such as high resolution, fast to deploy, and convenient to retrieve, and the proposed control scheme provides an effective approach for station-keeping attitude control of the earth observation platform.

Design and simulation of fault diagnosis based on NUIO/LMI for satellite attitude control systems

This paper presents a scheme of fault diagnosis for flexible satellites during orbit maneuver. The main contribution of the paper is related to the design of the nonlinear input observer which can avoid false alarm arising from the disturbance from orbit control force. The effects of orbit control force on the fault diagnosis system for satellite attitude control systems, including the disturbing torque caused by the misalignments and the model uncertainty caused by the fuel consumed, are discussed, where standard Lu- enberger observer cannot work well. Then the nonlinear unknown input observer is proposed to decouple faults from disturbance, Besides, a linear matrix inequality approach is adopted to reduce the effect of nonlinear part and model uncertainties on the observer. The numerical and semi-physical simulation demonstrates the effectiveness of the proposed observer for the fault diagnosis system of the satellite during orbit maneuver.

Attitude Control of a Flexible Solar Power Satellite Using Self-tuning Iterative Learning Control

This paper proposes a self-tuning iterative learning control method for the attitude control of a flexible solar power satellite,which is simplified as an Euler-Bernoulli beam moving in space.An orbit-attitude-structure coupled dynamic model is established using absolute nodal coordinate formulation,and the attitude control is performed using two control moment gyros.In order to improve control accuracy of the classic proportional-derivative control method,a switched iterative learning control method is presented using the control moments of the previous periods as feedforward control moments.Although the iterative learning control is a model-free method,the parameters of the controller must be selected manually.This would be undesirable for complicated systems with multiple control parameters.Thus,a self-tuning method is proposed using fuzzy logic.The control frequency of the controller is adjusted according to the averaged control error in one control period.Simulation results show that the proposed controller increases the control accuracy greatly and reduces the influence of measurement noise.Moreover,the control frequency is automatically adjusted to a suitable value.

Research on feasibility of missile attitude control based on laser gyroscope

According to the disadvantages of traditional mechanical gyro inertial measurement unit('IMU') for steering system not being available for missile attitude control, a concept based on laser gyro IMU is proposed to realize navigation & positioning and attitude control. The concept will save three single-axis rate gyros compared with traditional missile attitude control system, and is available both for strapdown and platform inertial navigation systems. Firstly, this article analyzes the selection requirements of sensitive device for missile attitude control system, and then analyzes the feasibility of missile attitude control based on laser gyro theoretically, on this basis, from four aspects of error characteristics, anti-vibration characteristics, temperature characteristics and dynamic characteristics, validate the feasibility of the concept practically. Secondly according to the strict requirements of dynamic characteristics on attitude control system, a special design is made for gyro signal filtering used for attitude control. By changing the traditional high order FIR filter to adaptive filter and low order FIR filter, laser gyro's signal phase delay is reduced. The delay time of theoretical design is 1.5 ms. Lastly, this design is validated through an angle vibration test, and test curve indicates that the dynamic characteristics of laser gyro completely meets the requirements of the attitude control system, and the maximum delay time is 1.6144 ms, which satisfies with the attitude update rate of 2 ms per frame. This concept can simplify the missile guidance system design, at the same time, it does not reduce missile guidance accuracy, and also provides reference for the broadening of the application of laser gyro.

Robust Adaptive Attitude Control for Non-rigid Spacecraft With Quantized Control Input

In this paper,an adaptive backstepping control scheme is proposed for attitude tracking of non-rigid spacecraft in the presence of input quantization,inertial uncertainty and external disturbance.TThe control signal for each actuator is quantized by sector-bounded quantizers,including the logarithmic quantizer and the hysteresis quantizer.By describing the impact of quantization in a new affine model and introducing a smooth function and a novel form of the control signal,the influence caused by input quantization and external disturbance is properly compensated for.Moreover,with the aid of the adaptive control technique,our approach can achieve attitude tracking without the explicit knowledge of inertial parameters.Unlike existing attitude control schemes for spacecraft,in this paper,the quantization parameters can be unknown,and the bounds of inertial parameters and disturbance are also not needed.In addition to proving the stability of the closed-loop system,the relationship between the control performance and design parameters is analyzed.Simulation results are presented to illustrate the effectiveness of the proposed scheme.

Mixed H_2/H_∞ State Feedback Attitude Control of Microsatellite Based on Extended LMI Method

For the appearance of the additive perturbation of controller gain when the controller parameter has minute adjustment at the initial running stage of system,to avoid the adverse effects,this paper investigates the mixed H_2/H_∞ state feedback attitude control problem of microsatellite based on extended LMI method.Firstly,the microsatellite attitude control system is established and transformed into corresponding state space form.Then,without the equivalence restriction of the two Lyapunov variables of H_2 and H∞performance,this paper introduces additional variables to design the mixed H_2/H_∞ control method based on LMI which can also reduce the conservatives.Finally,numerical simulations are analyzed to show that the proposed method can make the satellite stable within 20 s whether there is additive perturbation of the controller gain or not.The comparative analysis of the simulation results between extended LMI method and traditional LMI method also demonstrates the effectiveness and feasibility of the proposed method in this paper.

Control synthesis for polynomial nonlinear systems and application in attitude control

A method for positive polynomial validation based on polynomial decomposition is proposed to deal with control synthesis problems. Detailed algorithms for decomposition are given which mainly consider how to convert coefficients of a polynomial to a matrix with free variables. Then, the positivity of a polynomial is checked by the decomposed matrix with semidefinite programming solvers. A nonlinear control law is presented for single input polynomial systems based on the Lyapunov stability theorem. The control synthesis method is advanced to multi-input systems further. An application in attitude control is finally presented. The proposed control law achieves effective performance as illustrated by the numerical example.

An Improved Nonlinear Dynamic Inversion Method for Altitude and Attitude Control of Nano Quad-Rotors under Persistent Uncertainties

Nonlinear dynamic inversion(NDI)has been applied to the control law design of quad-rotors mainly thanks to its good robustness and simplicity of parameter tuning.However,the weakness of relying on accurate model greatly restrains its application on quad-rotors,especially nano quad-rotors(NQRs).NQRs are easy to be influenced by uncertainties such as model uncertainties(mainly from complicated aerodynamic interferences,strong coupling in roll-pitch-yaw channels and inaccurate aerodynamic prediction of rotors)and external uncertainties(mainly from winds or gusts),particularly persistent ones.Therefore,developing accurate model for altitude and attitude control of NQRs is difficult.To solve this problem,in this paper,an improved nonlinear dynamic inversion(INDI)method is developed,which can reject the above-mentioned uncertainties by estimating them and then counteracting in real time using linear extended state observer(LESO).Comparison with the traditional NDI(TNDI)method was carried out numerically,and the results show that,in coping with persistent uncertainties,the INDI-based method presents significant superiority.

Research on nonlinear attitude control algorithm for upper stage during multi-satellite disposing

For the issues of attitude strong coupling and the increments of attitude errors of upper stage during multi-satellite disposing,a three-axis stability nonlinear attitude control algorithm via feedback linearization is presented.By the definitions of coordinates and the attitude angle during multi-satellite disposing,the attitude dynamics and kinematics equations with Euler angles described are built.And the equations are equivalently linearized based on feedback linearization theory.A three-axis nonlinear predictive control algorithm is designed and the system robustness is analyzed.An example of mathematical simulation is completed using the Matlab/Simulink environment.Simulation results showed that the control algorithm has good disturbance rejection,rapidity,stability and robustness.

Attitude control allocation strategy of high altitude airship based on synthetic performance optimization

This paper presents a method for solving the attitude control problem of high altitude airship (HAA) with aerodynamic fin and vectored thruster control. The algorithm is based on the synthetic optimization of dynamic performance and energy consumption of airship. Firstly, according to the system overall configuration, the dynamic model of HAA was established and the HAA linearized model of longitudinal plane motion was obtained. Secondly, using the classic PID control theory, the HAA attitude control system was designed. Thirdly, through analyzing the dynamic performance of airship with fin or vectored thruster control, the synthetic performance index function with different weighting functions was determined. By means of optimizing the obtained performance index function, the attitude control of high altitude airship with good dynamic performance and low energy consumption was achieved. Finally, attitude control allocation strategy was designed for the airship station keeping at an altitude of 22 km. The simulation experiment proved the validity of the proposed algorithm.

Relative Position and Attitude Control for Drag-Free Satellite with Prescribed Performance and Actuator Saturation

An adaptive prescribed performance control scheme is proposed for the drag free satellite in the presence of actuator saturation and external disturbances.The relative translation and rotation dynamics between the test mass and outer satellite are firstly derived.To guarantee prescribed performance bounds on the transient and steady control errors of relative states,a performance constrained control law is formulated with an error transformed function.In addition,the requirements to know the system parameters and the upper bound of the external disturbance in advance have been eliminated by adaptive updating technique.A command filter is concurrently used to overcome the problem of explosion of complexity inherent in the backstepping control design.Subsequently,a novel auxiliary system is constructed to compensate the adverse effects of the actuator saturation constrains.It is proved that all signals in the closed?loop system are ultimately bounded and prescribed performance of relative position and attitude control errors are guaranteed.Finally,numerical simulation results are given to demonstrate the effectiveness of the proposed approach.