Hybrid Control Method Research Articles

원격제어 시스템의 종로봇인 이동 로봇의 제작과 힘 추종 제어 구현

In this paper, an implementation of force control for a slave mobile robot in tele-operation environment is presented. A mobile robot is built to have a force control capability with a force sensor and tested for force tracking control performances. Both position and contact force are regulated by a PID based hybrid control method and the impedance force control method. To minimize accumulated errors due to the adaptive impedance force control method, the novel force control method with a weighted function is proposed. Experimental studies of regulating contact forces for different control algorithms are tested and their performances are compared.

Predictive hybrid control of the supermarket refrigeration benchmark process

Predictive control is applied to a supermarket refrigeration process in which all actuators are on/off devices. This process has been proposed as a benchmark for the evaluation of hybrid control methods. It is shown that decentralized predictive control of display case temperatures, when combined with predictive control of suction manifold pressure, can greatly reduce or eliminate on/off compressor cycling. The strategy is scalable to large systems. Results are presented for an application involving 10 display cases and six compressors. Traditional hysteresis control causes synchronization of display case temperature oscillations. The proposed predictive approach includes desynchronization, which is shown to be necessary for minimization of compressor cycling. Finally, it is shown that the minimum possible number of compressor cycles can be estimated. This limit on control system performance is imposed by process design and operating conditions. It is also shown that the recommended predictive control strategy operates close to the minimum possible number of compressor cycles for the benchmark process.

Design and Implementation of Robust Hybrid Control of Vision Based Underactuated Mechanical Nonminimum Phase Systems

This paper presents a vision based Cart-Inverted Pendulum (CIP) system under a hybrid feedback configuration: the continuous cart’s position measured by encoder and the delayed & sampled inverted pendulum’s upper coordinates, obtained from a visual sensor. The challenge here is to stabilize the CIP from a big inclined initial angle by using a low cost CCD camera. Under this scheme, we propose a hybrid control which consists in a Jumpingup (Bang-Bang) control and a two causal stabilization loops control: the first one (inner loop) realizes a linearization and the stabilization control of the pendulum based on an innovative Piecewise Continuous Reduced Order Luenberger Observer coupled with a linearization module, the second one (the outer loop) realizes a Lyapunov based control for the unstable internal system with lower dynamics than that of the pendulum. This hybrid control method is capable of balancing the CIP system within small cart’s displacement. Performances issues of the proposed method are illustrated by the experimental figures and videos.

Fuzzy Hybrid Control of Vibration Attitude of Full Car via Magneto-rheological Suspensions

A magneto-rheological(MR) semi-active suspension system with the controllable damping forces has received more attention in reducing the vibration of a vehicle. However, many control strategies only discussed one or two vibration states of the vehicle based on a quarter-car model or a half vehicle model via MR suspensions. They cannot provide a satisfying whole-vehicle performance on a road test. Hence, a full car vibration model via an MR suspension system is proposed. To reduce the heave, pitch and roll motion of the vehicle body and the vertical vibration of four wheels, a fuzzy hybrid controller for vibration attitude of full car via MR suspensions is proposed. First, a skyhook-fuzzy control scheme is designed to reduce the heave, roll and pitch motion of the vehicle body. Second, a revised ground hook control strategy is adopted to decrease the vertical vibration of the wheels. Finally, a hybrid control scheme based on a fuzzy reasoning method is proposed to tune the hybrid damping parameter, which is suitable for coordination the attitude of the vehicle body and the wheels. A test and control system for the vibration attitude of full car is set up. It is implemented on a car equipped with four MR suspensions. The results on random highway and rough road indicate that the fuzzy hybrid controller can decrease the vibration accelerations of the vehicle body and the wheels to 65%–80% and 80%–90%, respectively. It reduces the automotive vibrations of heave, roll and pitch more effectively than a passive suspension and an MR suspension with a traditional hybrid control scheme so that it achieves better ride comfort and road holding concurrently. This paper proposes a new fuzzy hybrid control(FHC) method for reducing vibration attitude of full car via MR suspensions and develops a road test to evaluate the FHC.

Improved Hybrid Robust Control Method for the Electromechanical Actuator in Aircrafts

In the flight process of aircrafts, their electromechanical actuators(EMA) must have the ability of enduring uncertainties caused by factors such as load disturbance, the variation of work temperature and the EMA’s nonlinearity. At present, in order to increase the EMA’s robustness on the uncertainties, the H∞ control method has been applied in aircrafts. The major problems with standard H∞ control lie in the large overshoot of step response and the high orders of the controller. For the purpose of addressing the two problems, this paper investigates several kinds of robust control strategies of the EMA. A mathematical model of the EMA is first built, and then with MATLAB software a H∞ controller and an improved hybrid robust controller composed of a reduced order H∞ controller and a lead compensator are designed. In order to make a scientific comparison of the control effects of H∞ controller, hybrid controller and classic proportion-integral-differential(PID) controller, a simulation research is made in respect of the open loop frequency response and the closed loop step response of the three controllers. For comparing the robustness of the three controllers, the load torque is entered as a disturbance and the disturbance response of error and control input are thus obtained. The experiments with the three controllers are also conducted. Through giving the EMA a command and a disturbance torque successively, the transient response and disturbing process of EMA are recorded. The simulation and experiment results show that with the help of the hybrid controller, the EMA not only guarantees good dynamic characteristics, but also has strong robustness of disturbance rejection. Therefore, the excogitated H∞ hybrid control method effectively solves the problem of large overshoot in dynamic response, and moderately meets the requirement of overcoming the uncertainties in the EMA of aircrafts.

A Dynamic Hybrid Var Compensator and a Two-Level Collaborative Optimization Compensation Method

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> In this paper, a dynamic hybrid var compensator (HVC) for distribution grid is proposed. The system is based on a combination of a small-capacity distribution static compensator (DSTATCOM) and multigroup large-capacity thyristor switched capacitor (TSC). The DSTATCOM is the continuous subsystem of HVC, and the TSCs are the discrete subsystem of HVC. A new hybrid control method based on expert decision has been proposed to make sure that the HVC has good performance. A two-level collaborative optimization arithmetic, which is used to decide the optimal capacity of each HVC, has been proposed in this paper. A dynamic energy-saving system based on HVCs has been developed for a melt factory in southern China; application results show that compared to traditional reactive power compensation systems, the proposed system can effectively correct power factor, support supply voltage, mitigate voltage flicker, and obtain good effect for energy saving with low cost. </para>

PID제어기와 신경회로망 제어기를 이용한 유도전동기의 속도제어에 관한 연구

산업 자동화의 고정밀도에 따라 직류서보 전동기는 강인제어가 요구되고 있다. 하지만 PID 제어기를 갖는 전동기 제어 시스템이 부하 외란의 영향을 받게되면 제어 시스템의 강인제어는 어렵게 된다. 이에 대한 보완적인 한 방법으로 본 논문에서는 전동기 제어시스템을 위한 PID-신경망 복합형 제어기법을 제시하였다. 신경망 제어기의 출력은 부하 외란 인가시에 발생되는 오차와 오차 변화율에 의해서 결정된다. 신경망 제어기를 이용한 직류서보 전동기의 강인제어는 시뮬레이션에 의하여 확인하였다. Robust control for DC servo motor is needed according to the highest precision of industrial automation. However, when a motor control system with PID controller has an effect of load disturbance, it is very difficult to guarantee the robustness of control system. As a compensation method solving this problem, in this paper, PID-neural network hybrid control method for motor control system is presented. The output of neural network controller is determined by error and rate of error change occurring in load disturbance. The robust control of DC servo motor using neural network controller is demonstrated by computer simulation.

A Markovian model for the hybrid manufacturing planning and control method ‘Double Speed Single Production Line’

In this paper, the hybrid production planning & control method Double Speed Single Production Line (DSSPL) is presented, modelled and its performances evaluated and compared to classical Production Planning and Control methods (PPC). DSSPL combines JIT/kanban and Material Requirement Planning for the production of different classes of products (A- and B-items based on a market or customer oriented analysis) on one single production line. By the use of a Markovian birth–death queuing model of a single-stage, two-product production system, the performance and the behavior of the basic DSSPL concept are analyzed and compared to the classical MRP concepts. Its capability to cope with limited resources is illustrated with an industrial case study where DSSPL has been implemented to solve coordination problems between a plastic molding feeder shop and the final assembly line of a micromotor producer.

Hybrid control of hyperchaotic Lorenz system by constant impulse and adaptation impulse

The question about the control of hyper chaotic Lorenz system has been studied, and the method of hybrid control by constant impulse and adaptation impulse has been proposed according to the impulse control principle and the adaptive control policy. The method can extend the range of control parameter that can control the system to periodical orbit. The simulation results showed the effectiveness of this method.

Intelligent Hybrid Control of the Pneumatic Proportional System

Based on the non-linearization of pneumatic system,the neural-fuzzy control is embedded in the expert control,a comprehensive real-time intelligent hybrid control method is produced. It has not only the controller ability of logical reasoning and advanced intelligent behavior of the expert control,but also the instinct reasoning ability of the neural-fuzzy control,the coupled control method realizes the parallel control and knowledge sharing. The designed intelligent hybrid controller is introduced into the system model,and simulation on step signal is developed for the designed controllers and the others,the simulation result shows that the control system has a good rapidity and flexibility and the system moves smoothly,and it also shows good static and dynamic characteristics. The experiments prove that the hybrid controller designed for the non-linear characteristic is correct and effective.

Integrating a Grasp Exoskeleton Into a String-Based Interface for Human-Scale Interactions

A grasp exoskeleton actuated by a string-based platform is proposed to provide the force feedback for a user’s hand in human-scale virtual environments. The user of this interface accedes to seven active degrees of freedom in interaction with virtual objects, which comprises three degrees of translation, three degrees of rotation, and one degree of grasping. The exoskeleton has a light and ergonomic structure and provides the grasp gesture for five fingers. The actuation of the exoskeleton is performed by eight strings that are the parallel arms of the platform. Each string is connected to a block of motor, rotary encoder, and force sensor with a novel design to create the necessary force and precision for the interface. A hybrid control method based on the string’s tension measured by the force sensor is developed to resolve the ordinary problems of string-based interface. The blocks could be moved on a cubic frame around the virtual environment. Finally the results of preliminary experimentation of interface are presented to show its practical characteristics. Also the interface is mounted on an automotive model to demonstrate its industrial adaptability.

Controlling bifurcations and chaos in discrete small-world networks

We propose an impulsive hybrid control method to control the period-doubling bifurcations and stabilize unstable periodic orbits embedded in a chaotic attractor of a small-world network. Simulation results show that the bifurcations can be delayed or completely eliminated. A periodic orbit of the system can be controlled to any desired periodic orbit by using this method.

Hybrid static output feedback stabilization of two-dimensional LTI systems: a geometric method

For two-dimensional linear time-invariant (LTI) systems which are not stabilizable via a single static output feedback, we propose a hybrid stabilization strategy based on a geometric method. More precisely, we design two static output feedback gains and a switching law between the feedback gains so that the entire closed-loop system is asymptotically stable. The proposed switching law is composed of output-dependent switching and time-controlled switching. We demonstrate the hybrid control method with various examples for different cases.

Robust adaptive neuro-fuzzy controller for hybrid position/force control of robot manipulators in contact with unknown environment

In this paper, an adaptive control method for hybrid position/force control of robot manipulators, based on neuro-fuzzy modeling, is presented. Since force control involves applying certain amount ...

퍼지관리제어기법의 강인성능평가

This paper describes the robust performance of fuzzy supervisory control (FSC) approach for the seismic response control of cable-stayed bridges. FSC is a hybrid control method with the hierarchical structure of several sub-controllers and fuzzy supervisor. Each sub-controller is preliminarily designed to reduce the selected response of the structure only, and a fuzzy supervisor is introduced to improve the overall control performance by modulating the predesigned static gains into time-varying dynamic gains. To demonstrate the robust performance of the proposed strategy, the FSC and linear quadratic Gaussian (LQG) controller are optimally designed and their seismic performances are compared according to the variation of the bridge stiffness in the phase I benchmark control problem. The comparative results show that the FSC system can clearly guarantee the robust performance against the uncertainties of the bridge model.

A hybrid Jacobian control for uncalibrated robot visual servoing

This paper focuses on the visual servo control of an uncalibrated robotic arm with an eye-in-hand camera. Without a prior knowledge of the kinematics of the robotic arm or camera calibration, the proposed hybrid Jacobian controller can track a moving object using visual feedback and joint-space velocity feedback. The proposed hybrid control method is a combination of the uncalibrated visual servoing and approximate Jacobian feedback control. First, the Jacobian matrix from joint-space to image-space is estimated by recursive least-squares (RLS) algorithm, and then the approximate Jacobian feedback controller is designed by using visual feedback and joint-space velocity feedback. The performances of the proposed control methods are illustrated by computer simulations.

Fuzzy supervisory control of earthquake-excited cable-stayed bridges

A fuzzy supervisory control (FSC) technique is proposed for the seismic response control of cable-stayed bridges. The proposed technique is a hybrid control method, which adopts a hierarchical structure consisting of several sub-controllers and a fuzzy supervisor. The sub-controllers are independently designed in order to reduce the selected responses of a cable-stayed bridge and a fuzzy supervisor is introduced to modulate the pre-designed static gains into time-varying dynamic gains to improve seismic performance. In the design of the sub-controllers, shear forces and bending moments at the base of the towers, longitudinal displacements at the top of the towers, relative displacements between the deck and the tower, and tensions in the stay cables were selected as control variables. To demonstrate the effectiveness of the proposed strategy, example designs and numerical simulations were performed using a benchmark cable-stayed bridge subject to three historically recorded earthquakes. For comparison of the seismic performance, an optimally designed LQG system is also simulated for the benchmark bridge. The simulated results show that the FSC system can efficiently reduce the seismic responses of the cable-stayed bridge while maintaining lower control efforts.

Hybrid Control of Networked Embedded Systems

Hybrid systems that involve the interaction of continuous and discrete dynamics have been an active area of research for a number of years. In this paper, we start by briefly surveying the main theoretical control problems that have been treated in the hybrid systems setting and classify them into stabilization, optimal control and language specification problems. We then provide an overview of recent developments in four of the most prominent areas where these hybrid control methods have found application: control of power systems, industrial process control, design of automotive electronics and communication networks.

An Open-Architecture-Based Hybrid Control Method with a Weak Coupling Between Position Feedback-Loop and Force Feedback-Loop (Application to a Mold Polishing Robot)

Cutter location (CL) data with normal vectors can be used for not only a desired trajectory of tool's translational motion but also desired force directions for a mold polishing robot. In this paper, such normalized tool vectors are systematically generated from 3-axis CL data. The resultant CL data allow the polishing robot with an abrasive tool to realize a teaching-less operation of position and force. The present robot can also control the polishing force consisting of the contact and kinetic friction forces. During the polishing of a mold, a position feedback loop has a delicate contribution to the force feedback loop in Cartesian space so that a stable force control and an accurate pick feed control can be simultaneously achieved. The effectiveness and validity of the proposed robot have been proved by actual polishing experiments using a duralumin mold with curved surface.

ADAPTIVE NEURO-FUZZY CONTROLLER FOR HYBRID POSITION/FORCE CONTROL OF ROBOTIC MANIPULATORS

In this paper, an adaptive control method for hybrid position/force control of robot manipulators, based on neuro-fuzzy modelling, is presented. Also, an adaptive neuro-fuzzy compensator compensates the friction force between the endeffector and the surface of the object. Due to the adaptive neuro-fuzzy modelling, the proposed controller is independent of the robot dynamics. Also, the stability of the controller is guaranteed, since the adaptation law is based on Lyapunov theory. The simulation results show good performance of the proposed controller as compared with other conventional control schemes such as computed torque method.