Satellite attitude performance during the momentum dumping mode.

In this paper, the active magnetic control technique is applied for controlling the attitude and nutation of roll/yaw ares as well as unloading the excess wheel angular momentum for a small biased-momentum satellite in a nominal operation. Two control structures are configured using 2 and 3 magnetic torquers. The proportional controller is used for the attitude and nutation control of roll/yaw ares while the proportional-integral controller is used for the wheel momentum unloading task Both systems are evaluated through numerical treatments and compared particularly during the momentum unloading process. The performance from simulations exhibits that both systems fulfill the mission requirements. However, the system that uses 3 magnetic lorquers gives a better attitude performance

A Study Of Coupled Magnetic Fields For An Optimum Torque Generation

Magnetic torquers are specifically designed to generate a magnetic field onboard the satellites for their attitude control. A control torque is generated when the magnetic fields generated by the magnetic torquers couple with the geomagnetic fields, whereby the vector of the generated torque is perpendicular to both the magnetic fields

An optimum magnetic control torque generation of a momentum bias satellite

This paper describes a comparison study of magnetic attitude control torque generation performance of a momentum bias satellite operated in Low Earth Orbit (LEO) with various orbit inclinations. The satellite is equipped with two magnetic torquers that are placed along the +x and +y axes where magnetic control torque is generated when these magnetic torquers couple with the geomagnetic fields and its vector direction is perpendicular to both the magnetic fields. The control algorithm was structured using a proportional (P) controller for satellite attitudes/nutation control and a proportional-integral (PI) controller for managing the excess angular momentum on the momentum wheel. The structured control algorithm is simulated for 23°, 53° and 83° orbit inclinations and the generated attitude torque performances are compared to see how the variation of the satellite orbit affects the satellite’s attitude torque generation as the magnitude and direction of the geomagnetic fields vary with respect to the altitude and latitude while the magnitude and direction of the magnetic fields generated by the magnetic torquers vary with respect to the orbital motion. Results from simulation show that the higher orbit inclination generates optimum magnetic attitude control torque. Note that this work is the extension of the previous work published in The International Journal of Multiphysics [1]

An effective proportional-double derivative-linear quadratic regulator controller for quadcopter attitude and altitude control

A quadcopter control system is a fundamentally difficult and challenging problem because its dynamics modelling is highly nonlinear, especially after accounting for the complicated aerodynamic effects. Plus, its variables are highly interdependent and coupled in nature. There are six controllers studied and analysed in this work which are (1) Proportional–Integral–Derivative (PID), (2) Proportional-Derivative (PD), (3) Linear Quadratic Regulator (LQR), (4) Proportional-Linear Quadratic Regulator (P-LQR), (5) Proportional-Derivative-Linear Quadratic Regulator (PD-LQR) and lastly (6) the proposed controller named Proportional-Double Derivative-Linear Quadratic Regulator (PD2-LQR) controller. The altitude control and attitude stabilization of the quadcopter have been investigated using MATLAB/Simulink software. The mathematical model of the quadcopter using the Newton–Euler approach is applied to these controllers has illuminated the attitude (i.e. pitch, yaw, and roll) and altitude motions of the quadcopter. The simulation results of the proposed PD2-LQR controller have been compared with the PD, PID, LQR, P-LQR, and PD-LQR controllers. The findings elucidated that the proposed PD2-LQR controller significantly improves the performance of the control system in almost all responses. Hence, the proposed PD2-LQR controller can be applied as an alternative controller of all four motions in quadcopters

Interlaminar stress analysis for carbon/epoxy composite space rotors

This paper extends the previous works that appears in the International Journal of Multiphysics, Varatharajoo, Salit and Goh (2010). An approach incorporating cohesive zone modelling technique is incorporated into an optimized flywheel to properly simulate the stresses at the layer interfaces. Investigation on several fiber stacking sequences are also conducted to demonstrate the effect of fiber orientations on the overall rotor stress as well as the interface stress behaviour. The results demonstrated that the rotor interlaminar stresses are within the rotor materials’ ultimate strength and that the fiber direction with a combination of 45°/-45°/0° offers the best triple layer rotor among the few combinations selected for this analysis. It was shown that the present approach can facilitate also further investigation on the interface stress behaviour of rotating rotors

Magnetic attitude control options for earth pointing small satellite

The active magnetic attitude control technique is a promising attitude control option for small satellites operated in Low Earth Orbit (LEO). It is accomplished using sets of magnetic torquer that can generate a mechanical torque thus producing control actions when the torquers interact with the geomagnetic field. The magnetic attitude control structure can be developed based only on the magnetic torquers or in conjunction with other actuators. The purpose of this thesis is to develop and evaluate the options for the active magnetic attitude control system of low-cost small satellite missions. Three options of control algorithms have been developed for a gravity-gradient satellite and a momentum bias satellite. The first algorithm is structured for the gravity-gradient satellite employing three magnetic torquers onboard (Option A). The algorithm has been configured for controlling roll, pitch and yaw attitudes using a proportional-derivative (PD) controller. The second and the third algorithms are structured for the momentum bias satellite employing three (Option B) and two (Option C) magnetic torquers onboard, respectively. The structured algorithms are for controlling the attitude and nutation of roll/yaw axes using a proportional controller (P) as well as unloading the excess angular momentum of the wheel using a proportional-integral (PI) controller. The developed control algorithms are modeled using the MATLAB SIMULINK codes. The developed control algorithms were tested using the complex and simplified geomagnetic models for a reference space mission. Their attitude performances were compared and it is found that the accuracies of all the three developed control algorithms are comparable and fulfill the mission requirements. However, the system in option B satellite gives a better attitude performance with a perfect pointing accuracy along the pitch axis, whereas between −0.05° and 0.15° along the roll axis and between −0.05° and 0.3° along the yaw axis. This research is dedicated for LEO small satellites in a nominal attitude control operation and it provides us the trade-offs when designing the magnetic attitude control subsystem for low-cost space missions

New satellite attitude control structure using the geomagnetic field

The geomagnetic field is the main source of information considered when dealing with the magnetic attitude control system of a satellite. In this regards, the mathematical model of the geomagnetic field is described first in this paper.The simulation has been performed for the complex and simplified models, and the results show that the generated Earth’s magnetic field values are almost identical for both models. For demonstration purposes, the simplified model is chosen to simulate the attitude control system of the small satellite. The performance of the system exhibits that the attitude steady state error is achieved with values of ±0.5 degrees. Thus, the magnetic attitude control system is a promising option for small satellites

An active force controlled of small CMG-based satellite

Purpose: This paper aims to investigate the attitude control pointing improvement for a small satellite with control moment gyroscopes (CMGs) using the active force control (AFC) method. Design/methodology/approach: The AFC method is developed with its governing equations and integrated into the conventional proportional-derivative (PD) controller of a closed-loop satellite attitude control system. Two numerical simulations of an identical attitude control mission namely the PD controller and the PD+AFC controller were carried out using the MATLAB®-SimulinkTM software and their attitude control performances were demonstrated accordingly. Findings: Having the PD+AFC controller, the attitude maneuver can be completed within the desired slew rate, which is about 2.14 degree/s and the attitude pointing accuracies for the roll, pitch and yaw angles have improved significantly by more than 85% in comparison with the PD controller alone. Moreover, the implementation of the AFC into the conventional PD controller does not cause significant difference on the physical structure of the four single gimbal CMGs (4-SGCMGs). Practical implications:To achieve a precise attitude pointing mission, the AFC method can be applied directly to the existing conventional PD attitude control system of a CMG-based satellite. In this case, the AFC is indeed the backbone for the satellite attitude performance improvement. Originality/value: The present study demonstrates that the attitude pointing of a small satellite with CMGs is improved through the implementation of the AFC scheme into the PD controller

Proportional Double Derivative Linear Quadratic Regulator Controller Using Improvised Grey Wolf Optimization Technique to Control Quadcopter

A hybrid proportional double derivative and linear quadratic regulator (PD2-LQR) controller is designed for altitude (z) and attitude (roll, pitch, and yaw) control of a quadrotor vehicle. The derivation of a mathematical model of the quadrotor is formulated based on the Newton–Euler approach. An appropriate controller’s parameter must be obtained to obtain a superior control performance. Therefore, we exploit the advantages of the nature-inspired optimization algorithm called Grey Wolf Optimizer (GWO) to search for those optimal values. Hence, an improved version of GWO called IGWO is proposed and used instead of the original one. A comparative study with the conventional controllers, namely proportional derivative (PD), proportional integral derivative (PID), linear quadratic regulator (LQR), proportional linear quadratic regulator (P-LQR), proportional derivative and linear quadratic regulator (PD-LQR), PD2-LQR, and original GWO-based PD2-LQR, was undertaken to show the effectiveness of the proposed approach. An investigation of 20 different quadcopter models using the proposed hybrid controller is presented. Simulation results prove that the IGWO-based PD2-LQR controller can better track the desired reference input with shorter rise time and settling time, lower percentage overshoot, and minimal steady-state error and root mean square error (RMSE)

An Explosion Based Algorithm to Solve the Optimization Problem in Quadcopter Control

This paper presents an optimization algorithm named Random Explosion Algorithm (REA). The fundamental idea of this algorithm is based on a simple concept of the explosion of an object. This object is commonly known as a particle: when exploded, it will randomly disperse fragments around the particle within the explosion radius. The fragment that will be considered as a search agent will fill the local space and search that particular region for the best fitness solution. The proposed algorithm was tested on 23 benchmark test functions, and the results are validated by a comparative study with eight well-known algorithms, which are Particle Swarm Optimization (PSO), Artificial Bee Colony (ABC), Genetic Algorithm (GA), Differential Evolution (DE), Multi-Verse Optimizer (MVO), Moth Flame Optimizer (MFO), Firefly Algorithm (FA), and Sooty Tern Optimization Algorithm (STOA). After that, the algorithm was implemented and analyzed for a quadrotor control application. Similarly, a comparative study with the other algorithms stated was done. The findings reveal that the REA can yield very competitive results. It also shows that the convergence analysis has proved that the REA can converge more quickly toward the global optimum than the other metaheuristic algorithms. For the control application result, the REA controller can better track the desired reference input with shorter rise time and settling time, lower percentage overshoot, and minimal steady-state error and root mean square error (RMSE)