Attitude Controller Design Research Articles

Robust position control design for a cylinder in mobile hydraulics applications

Automation of various agricultural tasks, which are nowadays routinely executed by operators of hydraulically actuated tractors equipped with front-end loaders, is an important open problem. The so-called self-leveling task is considered here, where the lifting and lowering motions of the loader are performed manually while the orientation of the tool must be adjusted automatically. The proposed controller is constituted by a proportional feedback, a disturbance compensator based on an observer and a relay controller. A model-based tuning procedure for the controller parameters is discussed and an implementation is validated experimentally on an industry-standard commercial set-up.

Attitude control design for flying boom during air-to-air refuelling

Compared with hose-and-drogue refuelling, flying boom refuelling has attracted increasing interest due to its high flow rates and easy contact operation. Aided by a flying boom attitude controller,...

Robust control of post-stall pitching maneuver based on finite-time observer

This article presents a robust finite-time maneuver control scheme for the longitudinal attitude dynamic of the aircraft with unsteady aerodynamic disturbances and input saturation. To efficiently eliminate the influence of unsteady aerodynamic disturbances, nonlinear finite-time observers are developed. Despite the existence of the nonlinearity and the coupling between aircraft states and unsteady aerodynamic disturbances, the proposed observers can still precisely estimate the unmeasurable unsteady aerodynamic disturbances in finite time. To attenuate the effect caused by input saturation, a finite-time auxiliary system is constructed. With the error between the desired control input and saturation input as the input of the auxiliary system, the additional signals are generated to compensate for the effect of input saturation. Combined with the finite-time observers and the finite-time auxiliary system, a robust finite-time backstepping attitude control design is developed. The finite-time convergence of all closed-loop system 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.

Attitude and position controller design and implementation for a quadrotor

The performance of quadrotors can be significantly disturbed in the presence of wind. In this article, a simple-to-implement attitude controller is proposed to render a robust and accurate trajecto...

Real time implementation of H-infinity and RST motion control of rotary traveling wave ultrasonic motor

ABSTRACT This paper deals with design, performances comparison and experimental validation of H-infinity (H∞) and discrete time RST position controllers for a Traveling Wave Ultrasonic Motor (TWUM) which is dedicated to robotic applications. The proposed positioning system shows high precision levels of piezoelectric motor without additional hysteresis and dead zone compensation systems. Moreover, the perturbation rejection capability and the robustness to motor parameters variation are guaranteed. The synthesis procedure of robust H∞ and RST position controllers is detailed. The performances of the proposed controllers are validated by simulation and experimental results.

Lateral motion of the endless flat belt in a two-pulley belt system

An analytical model of the lateral motion of the endless belt in a two-pulley belt system is proposed. This model can be used to forecast the transient and steady lateral motion of the belt when the tilted angle of the steering pulley is time-variant and it is valuable in the design and assessment of belt lateral position controllers. The responses of the belt to variations in the tilted angle of the steering pulley according to a piecewise step function are solved using the delay differential equation solver dde23 in MATLAB. The validity of the model is confirmed by experiments. The simulation and experimental results show that the belt tends to move to the side with a shorter center distance. In the steady phase of the step responses, the lateral belt velocities at different positions tend to be coincident with each other. A closed-form expression of the steady belt lateral velocity is derived. The expression shows the steady belt lateral velocity is proportional to the input tilted angle and the belt speed, and it increases with an increase in the center distance and the pre-load tension and a decrease in the radius of the pulleys and the belt bending stiffness.

Coupling-Characterization-Based Robust Attitude Control Scheme for Hypersonic Vehicles

The issue of couplings makes the attitude control design for hypersonic vehicles (HSVs) challenging. This paper focuses on the characterization of coupling and its application in the control system synthesis. A novel coupling characterization index is introduced via the Lyapunov stability theory to indicate whether a coupling harms or benefits the system. The control scheme is designed to eliminate the detrimental couplings while keeping the beneficial couplings. The novelty of this paper is that the system couplings are explicitly utilized in the controller design leading to better dynamic performance. The robustness of the proposed controller is enhanced by using a disturbance observer. The effectiveness of the proposed scheme is validated by simulations in the HSV attitude system.

Design of Optimal Position Controller for Three-Phase Brushless DC Motor Applying Adaptive Sliding Mode Control

Design of Optimal Position Controller for Three-Phase Brushless DC Motor Applying Adaptive Sliding Mode Control

Design of mixed sensitivity H∞ control for four-rotor hover vehicle

During the past one decade, multirotor unmanned aerial vehicles (MUAVs)'s control has become an active research area for flight control community. The reasons behind are the benefits offered by MUAV and its numerous commercial and consumer applications. In this paper, design of a robust attitude controller for four-rotor hover vehicle that is a kind of MUAV, based on H∞ mixed-sensitivity synthesis is presented. Firstly, a linear model of four-rotor hover vehicle is derived, which is formulated as a nominal plant perturbed by parameter and unstructured uncertainties. H∞ mixed-sensitivity controller is designed due to the uncertain nature of the system. The efficacy of the proposed controller is proved by simulations and experiment. Performance analysis, simulation, and experimental results show that the proposed controller guarantees stability, exhibits good performance, and robustness margins against the parameter and unstructured uncertainties.

Finite-time attitude controller design via dual-loop control strategy

In this paper, a finite-time attitude control scheme based on the dual-loop framework is proposed for rigid spacecraft in the presence of inertia uncertainties, external disturbances, bounded angular velocity, and control input saturation. The control law was designed based on a dual-loop structure. First, a hyperbolic tangent function was used to design the virtual angular velocity command, which serves as the control input of the outer loop system to stabilize the attitude under angular velocity constraints. Second, a smooth function was used to approximate the saturation and an auxiliary system was constructed to compensate for the effects of actuator saturations. A finite-time control law was designed to track the limited command of the outer loop under the disturbance and control input constraints in the inner loop. The stability of the closed-loop system during saturation is thus guaranteed, and the tracking error converges to zero after controller parameters are selected appropriately. A numerical example illustrates the effectiveness of the proposed attitude controller.

Position Control of an Electrohydrostatic Actuator With Tolerance to Internal Leakage

This brief presents design and experimental evaluation of a fixed-gain position controller for the class of electrohydrostatic actuator that is tolerant to actuator internal leakage fault and robust to various environmental stiffnesses and system parametric uncertainties. Built upon quantitative feedback theory, the proposed controller is designed according to stability and tracking specifications, considering actuator internal leakage as one of the uncertain phenomena. The controller is also augmented with a friction compensator to alleviate the parasitic effect of dry friction in the hydraulic cylinder and further improve the tracking performance. The ability of the augmented controller in maintaining the actuator position within acceptable response envelopes is demonstrated in both simulations and experiments. More specifically, the experimental results show that the steady-state error of various step input responses remains within 0.1 mm despite an internal leakage flow rate as high as 8.5 L/min.

Robust attitude control for quadrotors with input time delays

Robust attitude controller design problem is investigated for uncertain quadrotors with input delays. The vehicle model can be described as a multiple-input multiple-output nonlinear system subject to parametric uncertainties, external disturbances, and input time delays. A robust controller is proposed consisting of a nominal controller and a robust signal-based compensator. It is shown that the robust stability and the robust tracking property can be achieved. An important feature of the proposed control method is that a systematic way can be given to tune the controller parameters. Experimental results are given to demonstrate the effectiveness of the designed control system.

Flexible attitude control design and on-orbit performance of the ZDPS-2 satellite

ZDPS-2, the 2nd generation nano-satellites designed and manufactured by Microsat Research Center of Zhejiang University, were successfully launched by the new generation rocket CZ-6 on Sep 20th, 2015. They are two 20kg identical nano-satellites (ZDPS-2-A and ZDPS-2-B) with a large deployable mechanism with a truss structure. The main mission of these two satellites is on-orbit demonstration of several new technologies, including large lightweight and flexible deployable mechanisms, a custom-designed panoramic wide field of view micro camera Sun sensor and infrared Earth sensor, and a micro-propulsion system as well as dual-satellite formation flying technology. The satellite is a 25cm cube with a deployable mechanism, whose fundamental frequency is only approximately 0.13Hz. This brings several challenges to attitude control. Flexible structure dynamics and its influence on attitude stabilization must be taken into consideration. A robust control scheme is developed by fully utilizing environmental torques with limited control actuator capability. On-orbit performance verified this design. ZDPS-2 satellites have successfully achieved rate damping, sun-pointing control and 3-axis stabilized Earth-pointing control, with a control accuracy of 5° (3σ) and stability superior to 0.1°/s (3σ). This paper demonstrates the flexible attitude dynamics modeling, illustrates the attitude control system design of ZDPS-2 and presents the on-orbit performance as well.

Second-order sliding mode attitude controller design of a small-scale helicopter

In this paper, the attitude control of a small-scale helicopter is investigated. The main rotor flapping dynamics is explicitly explored to improve the control performance. A two-layer control architecture is adopted: the inner loop controller is designed combining second-order sliding mode control with extended state observer to control the angular rates and yield good robustness properties with respect to model uncertainties; the outer loop controller is used to control the attitude. Experimental results show that the proposed controller yields excellent performance and robustness.

A Simple Method for Identifying Mechanical Parameters Based on Integral Calculation

A method for the identification of mechanical parameters based on integral calculation is presented. Both the moment of inertia and the friction constant are identified by the method developed here, which is based on well-known mechanical differential equations. The mechanical system under test is excited according to a pre-determined low-frequency sinusoidal motion, minimizing the distortion, and increasing the accuracy of the results. The parameters are identified using integral calculation, increasing the robustness of the results against measurement noise. Experimental data are supported by simulation, confirming the effectiveness of the proposed technique. The performance improvements shown here are of use in the design of speed and position controllers and observers. Owing to its simplicity, this method can be readily applied to commercial inverter products.

Robust adaptive backstepping control for autonomous spacecraft proximity maneuvers

The control problem of autonomous proximity phase during rendezvous and docking is studied for a chaser spacecraft subject to parametric uncertainty and unknown external disturbance approaching to a tumbling non-cooperative space target. A coupled relative motion model is established for the autonomous spacecraft proximity missions based on the relative motion information and chaser’s motion information. Based on the cascaded structure of the six degrees-of-freedom coupled model, the backstepping technology combined with element-wise and norm-wise adaptive control methods is used to design a relative position controller firstly, then the same method is also applied to the design of the relative attitude controller. Asymptotic stability is proven uniformly for the six degrees-of-freedom closed-loop system, and the performance of the controlled overall system is demonstrated via a representative numerical example.

Adaptive actuator failure compensation design for spacecraft attitude control

An adaptive actuator failure and disturbance compensation scheme is developed for attitude tracking control of spacecraft. The proposed scheme consists of a composite parameter adaptation design that incorporates an adaptive backstepping feedback control law and an adaptive feedforward actuator failure compensator; it can guarantee the overall closed-loop system stability and asymptotic tracking. Illustrative simulation results of an application to a spacecraft model show that the designed actuator failure compensation controller ensures system stability and tracking performance.

Constrained dual-loop attitude control design for spacecraft

A constrained dual-loop controller is designed for the attitude control of rigid spacecraft with inertia uncertainties, assigned angular velocity and control constraints. The design is based on a modular approach that the design of the control law and the online estimator leads to an important “separation property”. The control law is designed based on a two-loop structure in which the outer-loop control law implements by sliding mode control technique to stabilize the attitude under angular velocity constraints, and the inner loop control law is designed to track the limited command of outer loop under uncertainties and control input constraints. To improve the robustness of the attitude controller, an extended state observer is developed for online estimation of the lumped disturbance. The constraints on control input and angular velocity are implemented by second-order command filter. The stability of the subsystem during saturation is guaranteed by using a modified tracking error definition, in which the effect of the constraints has been filtered and removed. Simulation results are obtained to illustrate the effectiveness of the proposed attitude controller.

Robust and optimal attitude control of spacecraft with inertia uncertainties using minimal kinematic parameters

In this paper a robust and optimal attitude control design that uses the minimal kinematic parameters and angular velocities feedback is presented for the three-axis attitude stabilization of spacecraft with inertia uncertainties. After proposing a new class of robust attitude control laws for the three-axis attitude stabilization of spacecraft with inertia uncertainties, it is shown that the proposed robust attitude control laws are optimal with respect to performance indices. A numerical example is given to illustrate the theoretical results presented in this paper.

A Review on Recent Development of Spacecraft Attitude Fault Tolerant Control System

Motivated by several accidents, attitude control of a spacecraft subject to faults/failures has gained considerable attention in a wider range of aerospace engineering and academic communities. This paper is concerned with industrial practices and theoretical approaches for fault tolerant control (FTC) and fault detection and diagnosis (FDD) in spacecraft attitude control system. An overview on recent development of spacecraft attitude FTC system design is presented. The basis of a FTC system is introduced. The existing engineering FTC techniques and theoretical methodologies, including their advantages and disadvantages, are discussed. Moreover, closely associated with the reliability-relevant issues, recent progress in attitude FTC design strategies is reviewed. A brief review of some open problems in the general area of spacecraft attitude control design subject to components faults/failures is further concluded.