Robust Position Control Research Articles

Advanced shifting control of synchronizer mechanisms for clutchless automatic manual transmission in an electric vehicle

On the basis of improving drivability and efficiency, an electric vehicle equipped with automatic manual transmission is a considerable framing. However, the conventional geared transmissions usually install automated clutch which require the hydraulic power in addition to the slippage in the clutch plate invoking some energy loss as well as wear. For this reason, a practical approach with respect to clutchless automatic manual transmission (CLAMT) and its gear-shifting control strategy for an electric vehicle was proposed by our research team. In order to determine the key factors affecting the gear-shifting operation of CLAMT, a dynamic model of the CLAMT driveline was developed and the dynamic characteristics of the transmission synchronizer during each gear-shifting phase were analyzed in this paper. The analysis indicates that the gear-shifting operation of CLAMT not only requires a power motor with the capability of rapid mode-switching and precise speed regulation, but also demands that the shift actuators have the ability of exact position adjustment and strong robustness against shift load variations. To realize rapid and accurate gear-shifting control, the key technique relating to the robust position control scheme for the gear-shifting actuators were described in detail and validated on a designed CLAMT test rig.

Robust position control of a lab helicopter under wind disturbances

Flight performances of unmanned helicopters can be affected by wind gusts especially when they are carrying out aggressive mission. In this study, robust position control problem under aggressive manoeuvres is investigated in the presence of time-varying wind disturbances for a lab helicopter. A robust controller is designed in two steps: first, a nominal static linear feedback controller is applied to obtain desired tracking for the nominal system; then, a robust compensator is introduced to restrain the influences of parameter uncertainties, non-linear uncertainties and external wind disturbances. It is proven that the position tracking errors of the closed-loop system can be guaranteed to converge to a neighbourhood of the origin with designated boundary. Experimental results on the 3-degrees of freedom helicopter confirm the effectiveness of this method.

Robust Approach to Attitude Control and Momentum Management for Space Station

A novel methodology to design a robust attitude control and momentum management controller for the space station is proposed. Firstly, the method of maximum rank decomposition is adopted to deal with parameter uncertainties independently. Secondly, based on the resulted model, an optimal controller, with closed-loop region pole constraints, is designed. Finally, simulation results are presented to demonstrate the control effects.

A robust attitude control strategy with guaranteed transient performance via modified Lyapunov-based control and integral sliding mode control

In this paper, a robust control strategy with guaranteed transient performance is presented for spacecraft attitude maneuvers. Firstly, a Lyapunov-based controller is designed to achieve high-performance attitude control in the absence of disturbance and parameter variation. Unlike most existing designs, the feedback gains in the proposed controller increase with the attitude error convergence. Consequently, the system response can be accelerated without increasing the control torque at large attitude error. The overshooting phenomenon is also avoided by imposing a restriction on the parameter selection. Then, the integral sliding mode control technique is employed to preserve the desired transient characteristics and improve the robustness. Furthermore, by combining an adaptive scheme with the boundary layer method, the conservativeness in the switching gain selection is reduced and the chattering is also suppressed. Theoretical analysis and simulation results verify the effectiveness of the proposed strategy.

Design and Implementation of a Sliding Mode Attitude Controller of a Satellite in Software in the Loop Test Bed

In this paper, a robust attitude control algorithm is developed based on sliding mode control for a satellite using four reaction wheels in a tetrahedron configuration. In this method, asymptotic stability of the proposed algorithm has been proven on lyapunov theory. Then, in order to evaluate the performance of the proposed algorithm, a low-cost real-time software in the loop test bed is provided. The presented test bed is capable of real-time assessing the attitude sliding mode control algorithm. In this test bed, real-time modeling of satellite dynamic, environmental disturbances and reaction wheels are achieved in a simulator computer and the proposed control algorithm performance is investigated by implementing it in an electronic control board of the software in the loop test bed.

A DSP-based Robust Position Controller of a Single-sided Linear Induction Motor for Automatic Picking System

For application of a single-sided linear induction motor (LIM) to an automatic picking system (APS), this paper presents a DSP-based robust position controller design using an integral sliding mode control (SMC) scheme. To operate a movable ejector in the APS with high precision and high dynamics, a high performance linear motor drive system is required. The force disturbance as well as the mechanical parameter variations such as the mass and friction coefficient influence directly on the position control performance of APS. To guarantee a robust control performance in the presence of such uncertainty, an integral SMC-based position controller is considered. A Simulink library is developed for the LIM dynamic model. The entire system is realized using DSP TMS320F28335 based controller for performance comparison. Using the comparative simulations based on Matlab – Simulink and experiments, the effectiveness of the proposed scheme is verified. As a result, the proposed scheme has a robust control nature and is most suitable for an implementation of the APS.

Stability-Guaranteed Assist-as-Needed Controller for Powered Orthoses

This brief describes the assistance regulation controller (ARC), a nonlinear admittance controller for powered orthoses (POs) and wearable robotics that simultaneously facilitates task completion and encourages user effort. This brief also introduces a novel acceleration-limited proportional derivative controller (ALPDC) that guarantees the stability of the ARC's inner position control loop. The stability analysis of the ALPDC shows that this simple and robust position controller promotes safer human-robot interactions in a large class of admittance-controlled haptic devices. Both the ARC and ALPDC are implemented on a one-degree-of-freedom PO designed to assist forearm flexion and extension. Experiments performed by a healthy male subject confirm that the ALPDC guarantees stable user-device interactions and bounded tracking errors during highly dynamic forearm motions that lead to instability with a conventional controller.

Development of a two-wheel mobile manipulator: balancing and interaction control

SUMMARYThis paper focuses on practical application of a mobile manipulator by presenting the development and control of a two-wheel mobile robot with two arms called a balancing service robot (BSR) designated for indoor services. The mobile manipulator requires not only robust balancing position control but also force control to interact with objects. Movements with two wheels are controlled to satisfy stable balancing control for navigation and manipulation with two arms to perform given tasks. The robot is required to deal with external forces to maintain balance. The position-based impedance force control method (the admittance control) is utilized by filtering the force with the impedance function to react to the applied force from the operator. Experimental studies of navigation control under balancing condition and interacting control with a human operator are demonstrated. Experimental results confirm that the robot has smooth reaction against the disturbance induced by the applied external force.

Modeling and control of a self-sensing polymer metal composite actuator

An ion polymer metal composite (IPMC) is an electro-active polymer (EAP) that bends in response to a small applied electrical field as a result of mobility of cations in the polymer network and vice versa. One drawback in the use of an IPMC is the sensing problem for such a small size actuator. The aim of this paper is to develop a physical model for a self-sensing IPMC actuator and to verify its applicability for practical position control. Firstly, ion dynamics inside a polymer membrane is investigated with an asymmetric solution in the presence of distributed surface resistance. Based on this analysis, a modified equivalent circuit and a simple configuration to realize the self-sensing IPMC actuator are proposed. Mathematical modelling and experimental evaluation indicate that the bending curvature can be obtained accurately using several feedback voltage signals along with the IPMC length. Finally, the controllability of the developed self-sensing IPMC actuator is investigated using a robust position control. Experimental results prove that the self-sensing characteristics can be applied in engineering control problems to provide a more convenient sensing method for IPMC actuating systems.

Guaranteed transient performance based control with input saturation for near space vehicles

This paper describes the design of guaranteed transient performance based attitude control for the near space vehicle (NSV) with control input saturation using the backstepping method. To improve the robust controllability of the NSV, the parameter adaptive method is used to tackle the integrated effect of unknown time-varying disturbance and control input saturation. Based on the backstepping technique and parameter estimated outputs, a robust attitude control scheme is proposed for the NSV with input saturation. A novel robust attitude control scheme is then proposed based on a prescribed performance bound (PPB) which characterizes the convergence rate and maximum overshoot of the attitude tracking error. The closed-loop system stability under both the developed robust attitude control schemes is proved using Lyapunovs method and uniformly asymptotical convergence of all closed-loop signals is guaranteed. Finally, simulation results are given to show the effectiveness of both the proposed robust constrained attitude control schemes.

Nonlinear Robust Control for Spacecraft Attitude

Nonlinear robust control of the spacecraft attitude with the existence of external disturbances is considered. A robust attitude controller is designed based on the passivity approach the quaternion representation, which introduces the suppression vector of external disturbance into the control law and does not need angular velocity measurement. Stability conditions of the robust attitude controller are given. And the numerical simulation results show the effectiveness of the attitude controller. DOI : http://dx.doi.org/10.11591/telkomnika.v12i1.3477

Robust Attitude Control with Improved Transient Performance

This paper aims to present a robust attitude control strategy with guaranteed transient performance. Firstly, a Lyapunov-based control law is designed to achieve high-performance attitude control in the absence of disturbance and parameter variation. The proposed control law uses small feedback gains to suppress the control torque at large attitude error, and increases those gains with the convergence of attitude error to accelerate the system response. The overshooting phenomenon is also avoided by imposing a restriction on the parameter selection. Then, the integral sliding mode control technique is employed to improve the robustness, where the Lyapunov-based control law is used as the equivalent control part. Theoretical analysis and simulation results verify the effectiveness of the proposed strategy.

Robust attitude control of nano-satellite using control moment gyros based on higher order sliding modes

Rapid attitude orientation and stable pointing accuracy are critical characteristics for observation missions of nano-satellite nowadays. This paper focuses on analysis of attitude control law for nano-satellite TSUBAME which is developed by Laboratory of Space System at Tokyo Institute of Technology. In recent years, the higher order sliding mode control (HOSMC) is considered, which is more useful in handling the chattering effect against external disturbance and unknown friction effects. Furthermore, HOSMC can remove the chattering effect if appropriate relative degree was chosen. To overcome the singularity problem inherent in the control moment gyros, a modified steering law for single gimbal control moment gyros (SGCMG), which aims at precisely exporting commanded torque is discussed based on the optimal output torque capability principle. This paper includes a comparison between two different control algorithms in the attitude controlling system which used control moment gyro (CMG) as the actuator for TSUBAME. The numerical simulation results demonstrate the efficiency and feasibility of the proposed HOSMC algorithm.

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.

자동피킹 시스템 구동용 선형 유도 모터 드라이브 설계 및 적분형 가변구조 제어 기반의 강인 위치 제어기 설계

고 정밀도와 고 속응성의 물류 이송을 위한 자동피킹 시스템 (Automatic Picking System; APS) 구동용 선형 유도 모터 드라이브의 설계 및 강인한 위치 제어 기법이 제안된다. 모델 불확실성에 대한 강인한 위치 제어기 설계를 위해서 적분형 가변구조 제어 기법이 고려된다. APS의 외란추력, 질량 및 마찰계수 등의 기계적 파라미터 변화는 위치 제어 성능에 직접적 영향을 주며 이러한 불확실성 하에서도 강인한 위치 응답 성능을 보유하는 위치 제어기가 설계된다. 선형 유도 모터의 모델을 위한 Simulink 라이브러리가 상태방정식으로부터 개발되며 이를 활용한 Matlab - Simulink 기반의 비교 시뮬레이션을 통해 제안된 방식이 강인한 위치 응답 성능을 가지며 고 정밀도와 고 속응성을 요구하는 APS에 적합함이 입증된다. To implement an automatic picking system (APS) in distribution center with high precision and high dynamics, this paper presents a design of a linear induction motor (LIM) drive and robust position controller based on integral variable structure control (IVSC) scheme. The force disturbance as well as the mechanical parameter variation such as the mass and friction coefficient gives a direct influence on the position control performance of APS. To guarantee a robust control performance in the presence of such uncertainty, a robust position controller is designed. A Simulink library is developed for the LIM model from the state equation. Through this model and comparative simulation based on Matlab - Simulink, it is proved that the proposed scheme has a robust control nature and is most suitable for APS.

Optimization of Sphere Population for Electrostatic Multi-Sphere Method

To develop the robust relative position and orientation control algorithms for Coulomb charge control of spacecraft, accurate but computationally efficient electrostatic models are necessary. The multi-sphere method (MSM) predicts the interactions of a charged spacecraft using multiple conducting spheres. To improve the accuracy of this model further, a new method is proposed whereby equal radius spheres are placed uniformly on the surface of the spacecraft. The radius is chosen such that the MSM predicts the same self-capacitance for the conducting geometry as a numerical solution does. While similarities are identified between the new method and the established boundary element method, several key distinctions between the models are established. The accuracy of the new approach is verified using a simple system with two spheres, whereby its ability to capture-induced charge effects is highlighted. Then, a cylinder-sphere system is analyzed using 105 spheres on the cylinder and 30 spheres on the sphere, providing comparison with a previous three-sphere volume populated model for the cylinder. The surface populated model provides much higher accuracy in forces and torques when the separation distances are within 10 craft radii, but there is a little improvement outside this range. While the cylinder MSM with three spheres provides force solutions an order of magnitude quicker than the surface MSM method, the setup time for the surface populated MSM is two orders of magnitude faster.

Robust Position Tracking Control of an Electro-Hydraulic Actuator in the Presence of Friction and Internal Leakage

This paper proposes an improved robust position controller for the electro-hydraulic actuator system using the varying boundary layered sliding mode control scheme. The proposed scheme has the ability to improve the position tracking performance of the actuator in the presence of friction and internal leakage. The former is represented using the LuGre model while later is modelled as a turbulent flow. To evaluate the effectiveness of the proposed method, MATLAB simulations are carried out under friction and leakage effects. Its performance is compared with the conventional PID and fuzzy PID (FPID) methods. Finally, an experimental rig that comprises of a single-rod and double acting hydraulic cylinder is set up to validate the proposed idea. The software development is carried out in the DSpace 1104 environment using a TMS320F240 digital signal processor. The superiority of the proposed method over the PID and FPID in terms of tracking position is highlighted by simulation and experimental results.

Robust LQR Attitude Control of a 3-DOF Laboratory Helicopter for Aggressive Maneuvers

Robust attitude control problem for a three-degree-of-freedom (3-DOF) laboratory helicopter is investigated. The helicopter dynamics involves nonlinearity, uncertainties, and strong interaxis coupling. A robust controller is proposed with three parts: a nominal feedforward controller, a nominal linear quadratic regulation (LQR) controller, and a robust compensator. The LQR controller is applied to deal with a nominal linear error system derived by the feedforward control strategy and linearized approximation, while the robust compensator is designed to restrain the effects of uncertainties, nonlinear properties, and external disturbances. It is shown that the attitude tracking error of the closed-loop system can be guaranteed to converge to any given small neighborhood of the origin in a finite time. Experimental results on the 3-DOF laboratory helicopter demonstrate the effectiveness of the proposed control strategy.

Robust hierarchical control of a laboratory helicopter

This paper deals with the robust position control problem for a three degree-of-freedom (3DOF) laboratory helicopter. The 3DOF helicopter system is a nonlinear multiple-input multiple-output (MIMO) uncertain system, and has the elevation, pitch, and travel angles. The proposed robust controller is a hierarchical controller including an attitude controller and a position controller. The position controller generates the desired reference of the pitch angle based on the tracking error of the travel angle, while the attitude controller achieves the reference tracking of the pitch and elevation angles. It is proven that the tracking errors of the three angles can converge into the given neighborhoods ultimately. Experimental results on the laboratory helicopter demonstrate the effectiveness of the proposed hierarchical control strategy.

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.