Acceleration Feedback Control Research Articles

비행제어계 평가를 위한 항공기 공중모의 비행시험

전자식 비행제어 항공기의 비행제어계설계, 지상 모의 시험 및 공중 모의 비행시험에 의한 비행성 평가를 수행하였다. 전자식 비행제어 항공기는 고등훈련기 형상을 가지며, 세로축 비행제어법칙은 수직가속도와 피치 각속도 추종시스템이며, 가로/방향축 비행제어법칙은 롤 각속도 및 가로가속도 추정시스템을 채택하였다. 대상항공기의 비행운동 평가는 공중모의 시험 항공기를 활용하였으며, 비행시험결과 최대불안정 영역에서는 Level 1, 착륙 접근 영역에서는 Level 1/2의 만족할 만한 비행성 결과를 보여 본 비행제어계 설계 타당성을 입증하였다. The paper presented here covers the work associated with the flight control law design, ground based and in flight simulation and handling qualities assessment of the Fly-by-Wire type Aircraft (FBWA). The FBWA configurations are of the same generic form of the Korean advanced trainer. The normal acceleration (Nz) and pitch rate (q) feedback control system is employed for longitudinal axis and roll rate (p) and lateral acceleration (Ny) feedback flight control law is developed in lateral/ directional axis. The flight tests for the FBW A dynamics evaluation were executed for the target aircraft (FBWA) on the IFS (In-Flight-Simulator) aircraft . The test results showed that Level 1 handling qualities for the most unstable flight regime and Level 1/2 for the landing approach flight regime were achieved. And the designed FBWA flight control law has revealed acceptable CHR (Cooper-Harper handling qualities Ratings).

Control of a Civil Structure Using an Electric Machine with Semiactive Capability

This paper concerns the implementation of a brushless DC machine as a force actuator, for use in suppressing vibrations in civil structures. The machine has the dual capability of operation as an active as well as semiactive device. It operates semiactively by using the machine as a generator to convert mechanical energy to electrical energy which is then dissipated. The electrical network uses electronic switching to control the power flow from the machine. With the machine shaft connected to a gear reducer and ballscrew mechanism, the result is a device that resembles a linear damper with a controllable damping coefficient. The only external electrical power required is that which is needed to support the control system intelligence and to control the transistors, enabling the device to be operated on battery power. As an example of an application of such an actuator, simulations are performed in which the semiactive device is used to control a three-story structural model, with acceleration feedback control. The structural control system design approach is the well-established “clipped-optimal” method. Results suggest that this actuator is effective in simultaneously suppressing the interstory drifts and the absolute accelerations of the structure. A comparison is made to a similar configuration using a magnetorheological damper as the semiactive force device.

Tail Buffet Alleviation of High-Performance Twin-Tail Aircraft Using Piezostack Actuators

The phenomenon of the tail buffet is usually associated with high-angle-of-attack operations of a twin-tail aircraft. The unsteady pressures that result from the tail buffet, along with the aeroelastic coupling of the vertical tail structural assembly, cause vibrations of the empennage structural assembly. Such buffet-induced vibrations can shorten the fatigue life the empennage structure and limit the flight envelope of the aircraft due to the large amplitudes of the fin vibrations. Methods of alleviating the tail buffet-induced vibrations, by the use of smart structure concepts, is presented. Theoretical and experimental investigations were conducted to estimate and enhance the required control authority for tail buffet alleviation using piezoceramic-stack-based actuators. This was accomplished by designing an effective piezoelectric ceramic actuator assembly, developing procedures to place the sensors and actuators optimally on the vertical tail subassembly, designing controllers using acceleration feedback control concepts, and developing procedures to implement these controllers by using digital signal processor-based systems

Multi‐level design model and genetic algorithm for structural control system optimization

AbstractThe integrated optimum problem of structures subjected to strong earthquakes and wind excitations, optimizing the number of actuators, the configuration of actuators and the control algorithms simultaneously, is studied. Two control algorithms, optimal control and acceleration feedback control, are used as the control algorithms. A multi‐level optimization model is proposed with respect to the solution procedure of the optimum problem. The characteristics of the model are analysed, and the formulation of each suboptimization problem at each level is presented. To solve the multi‐level optimization problem, a multi‐level genetic algorithm (MLGA) is proposed. The proposed model and MLGA are used to solve two multi‐level optimization problems in which the optimization of the number of actuators, the positions of actuators and the control algorithm are considered in different levels. In problem 1, an example structure is excited by strong wind, and in problem 2, an example structure is subjected to strong earthquake excitation. Copyright © 2001 John Wiley & Sons, Ltd.

Variable structure methods in hydraulic servo systems control

In the general framework of hydraulic servo systems, this paper addresses the problem of position control in the presence of important friction nonlinearities. The accent falls on the variable structure methodology, as we try to use its intrinsic robustness properties. Several friction observers, including the one based on a variable structure approach, were incorporated and tested in an acceleration feedback control. Next, we present a novel implementation of a variable structure controller, which lumps friction and load as an external disturbance. Results of extensive experimental testing encourage the use of variable structure methods in a class of highly nonlinear hydraulic servo systems.

Enhancement of vehicle handling characteristics by suspension kinematic control

In this paper, the enhancement of vehicle handling characteristics through the active kinematic control system (AKCS) is investigated. AKCS can improve the stability and ride comfort of a vehicle by automatically controlling suspension geometry in accordance with the running conditions of a vehicle. The variable roll centre suspension concept in a McPherson strut suspension is proposed, and lateral acceleration feedback control is derived to calculate the control input. The independent rear wheel steering system, which controls both rear wheels independently and actively, is also proposed. To achieve this, three suggested positions for controlling the suspension geometry are considered. The first position is between the mounting point of the lower arm of a McPherson front suspension and the vehicle body. The second position is between the mounting point of the strut and the vehicle body. The third position is between the mounting point of the lateral link of the multilink rear suspension and the vehicle body. In order to evaluate the handling performance, a 15 degrees of freedom full vehicle model is constructed using the commercial multibody analysis program ADAMS. The control inputs for integrated control of the front and rear suspensions are defined, and roll centre migration and vehicle behaviour are investigated. In step steering and double lane change manoeuvres, the simulation results demonstrate that integrated kinematic control can adjust the roll centre migration, by which the handling characteristics of the AKCS vehicle such as roll angle, lateral acceleration and yaw rate are much improved.

リニアモータを用いた制振装置の高層建物への適用

This paper deals with an application of hybrid mass damper (HMD) using linear motor to an actual tall building which has a height of 101m. By using the linear motor as an actuator, the HMD has a simple structure, little noise of working and an easy maintenance as compared with those using normal AC servomotor, because the HMD has no mechanical part to translate form torque to linear force. Its controllers, for the 1st and 2nd modes of X translation and 1st mode of torsion of the objective building, are designed by H^∞ control theory for absolute acceleration feedback control. The control system becomes also more simply than those of current HMDs which use state feedback control by optimal regulator, because the feedback signals are only two absolute accelerations of the top floor. The performance of the HMD is confirmed through excitation tests of the building and simulations against winds.

Joint acceleration feedback control for robots: analysis, sensing and experiments

Independent joint control for robots is enhanced to suppress the dynamic couplings by incorporating an acceleration feedback loop that is designed in terms of its stability and ability in resisting the dynamic coupling disturbances. The sensing and modeling of joint acceleration via linear accelerometers is dealt from the viewpoint of practical implementation. Extensive experiments are conducted on a three-link direct drive robot, to mainly investigate the ability of the independent joint controller with the acceleration loop in resisting the coupling torque, and demonstrating the enhanced trajectory tracking performance. Results are given against the ones obtained by conventional independent joint control without the acceleration feedback control.

Multi-level optimal design of buildings with active control under winds using genetic algorithms

The goal of this paper is to study the complicated optimal design problem of integrating the number of actuators, the configuration of the actuators and the active control algorithms in buildings excited by strong wind force. To do this, the following sequential studies are carried out: (1) Two control algorithms, linear quadratic regulator (LQR) and acceleration feedback control algorithm, are analyzed and used as the control algorithms. (2) The characteristics of the optimal design problem are analyzed in detail by a simulation study. (3) A multi-level optimization model is proposed, and the formulation of sub-optimization problems in each level is presented. (4) To solve the multi-level optimization problem, a multi-level genetic algorithm (MLGA) is proposed. The properties and implementation of MLGA are given and analyzed in detail. Finally, the optimal design model and the corresponding solving algorithm are tested by numerical simulation. The results show that: (1) in the design of actively controlled structures subjected to strong wind excitation, the problem of considering the number of actuators, the position of actuators and the control algorithm simultaneously is of a multi-level design optimization with the properties of non-linearity, discreteness and so on. (2) This kind of optimization problem should be described naturally by the multi-level design model. (3) The multi-level genetic algorithm can solve this complicated problem effectively. (4) The optimal locations of actuators depend on the control approaches.

Contact transition control via joint acceleration feedback

Stable and controllable transition from free motion to constrained motion is of central importance for robots in contact with the environment in many applications. In this paper, a joint acceleration feedback control scheme of high bandwidth is employed to damp oscillations during the contact transition when the approaching speed does not vanish. In this control scheme, a classical integral force controller is refined by means of joint acceleration and velocity feedback. This is intended to achieve a stable contact transition without need of adjusting the controller parameters adaptive to the unknown or changing environments. Extensive experiments are conducted on the third joint of a three-link direct-drive robot to verify the proposed scheme for the environments of various stiffnesses, including elastic (sponge), less-elastic (cardboard), and hard (steel plate) surfaces. Results are also compared with those by the transition control without the acceleration feedback. The proposed scheme is shown to be promising in terms of robustness, stability and adaptability.

Study on sensor-based control method for harmonic drive system

A new type of robust traje ctory tracking control for harmonic using joint torque sensor and joint acceleration sensor information is concerned with.Joint torque sensor information is used to compensate the uncertainty of link and load parameters. Joint acceleration feedback control will enhace the robustness of the driving system, resist the dynamic uncertainties and disturbing torque acted on the joint axis within definite bandwidth, improve the joint tracking performance, and resist the vibration of the ...

Single Actuator and Multi-Mode Acceleration Feedback Control

The objective ofthe paper is to develop avibration control design procedure that uses a single actuator to suppress vibrations in many structural modes simultaneously by using acceleration feedback control theory. In this paper, a new technique, based on the crossover point design of the compensator, has been developed to compute optimal design parameters to achieve modal vibration reduction without introducing any new natural frequencies in the closed loop system. The new technique has been validated by both experimental studies and simulation studies. The new design procedure has also been compared experimentally and analytically to a previous design of acceleration feedback controller by using critically damped compensators. Then, experimental and analytical investigations are directed to control more than one mode of a cantilevered beam with a single actuator. This is demonstrated by using piezoceramic wafer actuators and an accelerometer sensor on the beam structure.

Fault tolerant structural control systems for civil engineering applications

AbstractThe objective of this work is to experimentally examine some practical issues relating to the reliability and performance of active structural control systems. Using the newly constructed shaking table in the Department of Structural Mechanics at the University of Pavia, experiments were conducted employing an actively controlled, three story test structure. A DC‐motor based active mass driver system was used as the active control device. An H2/LQG controller based on acceleration feedback is applied to the system. The first objective of this work is to demonstrate the efficacy of the acceleration feedback control strategy. Next, two experiments are conducted with the goal of investigating fault tolerant control system design. In the first case, the occurence of a sensor failure is simulated experimentally, and the resulting controlled performance and robustness characteristics are assessed. The second set of tests is to evaluate the ability of the controller to reduce the structural responses when reduced information is available for control action determination. Both of these issues are important practical concerns in the design and implementation of a structural control system.

Tracking control of an electrohydraulic manipulator in the presence of friction

Analysis and estimation of friction and compensation for its effects in the control of an electrohydraulic manipulator is addressed. The specific hydraulic manipulator is an integral part of an automated fish processing machine which has been developed in our laboratory. The analysis reveals that considerable static and dynamic friction exists in the system. An available nonlinear observer for Coulomb friction, is modified to simultaneously estimate friction, velocity, and acceleration. A novel observer-based friction compensating control strategy is developed for improved tracking performance of the manipulator. The approach is based on acceleration feedback control. Experimental investigations show that this controller significantly outperforms the conventional PD controller. The general approach presented in this paper, may be applied to compensate for friction in any servomechanism, particularly when the actuator dynamics is not negligible.

ON ANALOG FEEDBACK CONTROL FOR MAGNETOSTRICTIVE TRANSDUCER LINEARIZATION

The magnetostrictive transducer output force, displacement, and bandwidth characteristics are well suited for a variety of active vibration control applications. However, their use is limited in part because these transducers are known to be non-linear. The transducer in this study is assumed to be a linear system and its output harmonics are assumed to be disturbance inputs. Two feedback control models are proposed and one is used to obtain expressions for predicting the change in harmonic amplitudes of displacement and acceleration as functions of frequency and parameters for the controller, load, and transducer. An approach based on magnetostrictive transduction modelling is presented for experimentally determining appropriate transducer model parameters for use in the feedback control model. Experimental measurements using simple, analog, PD (proportional plus derivative) acceleration feedback control are presented to validate the expressions. The closed loop feedback control system model resulted in predicted changes in harmonic acceleration amplitudes ranging from +2 to −30 dB (depending upon the frequency of the disturbance input) that were verified experimentally. A significant extension of the linear range of transducer behaviour, due to feedback control, is also demonstrated.

Acceleration feedback control of seismic structures

The essential feedback signals for direct output feedback control are limited to velocities and direct acceleration feedback control is found to be unfeasible even though accelerometers are favorable sensors from the viewpoint of measurement. In this paper, acceleration feedback control becomes feasible when the feedback data is extended to cover accelerations of the previous time-steps. A multi-step acceleration feedback control algorithm is derived through an optimization process such that a certain prescribed quadratic performance index is minimized. Control forces are simply generated from acceleration information of the current and previous time-steps. The feasibility of the proposed control algorithm is verified numerically by the tendon control of structures subjected to real earthquake excitation. The control effectiveness of the proposed control algorithm is close to that of state feedback control algorithm. Simple on-line calculation and availability of accelerometers make the proposed control algorithm favorable to realtime control implementation.

Control Methods for Active Mass Damper Using Linear Motor for Vibration Control of Tall Buildings.

Linear motors are promising actuators for active mass dampers, because driving mechanisms using them become more simple, reliable and efficient than those of current mass dampers which use AC servomotors and hydraulic actuators. Control methods using directly measured absolute accelerations of the buildings as feedback signals, are expected to he more reliable than those of current mass dampers using relative velocities and displacements to the ground which are calculated from the absolute accelerations. In this study, controllers were designed for the acceleration feedback control for a mass damper using a linear motor, based on the H∞ control theory and a model-matching method. A gain-scheduled control law was also developed for the acceleration feedback control. Excitations tests were carried out for a 5-story building model of a 5 800 kg total mass and a 3.4 m height with a mass damper model on the roof. Through the tests, it was shown that the H∞ controllers had higher performance than the model-matching controllers, and the gain-scheduled control law was very effective.

Vibration Suppression Using Acceleration Feedback Control with Multiple Proof-Mass Actuators

The use of direct acceleration feedback control for vibration suppression of low-frequency multi-degree-of-freedom flexible structures using multiple proof-mass actuators is investigated. Considering the effect of actuator dynamics, closed-loop eigenvalue analysis is conducted, and a simple matrix inequality is obtained for the stability condition of the closed-loop system. Methods for calculation of the stability condition are suggested. A procedure for actuator parameter optimization is proposed to assure the closed-loop system performance. Using both a lumped-mass space structure model and a frame structure model, numerical analysis and simulations are performed, and several aspects relating to control design are discussed. The results indicate the effectiveness of acceleration feedback control for low-frequency vibration suppression using proof-mass actuators.

Approximate pole placement for acceleration feedback control of flexible structures

Approximate pole placement for acceleration feedback control of flexible structures

Feedback Control Stability Analysis of Linear Slider Mechanism.

Mechanical control can be made stable by taking into consideration mechanical resonance frequency and antiresonance frequency. A mechanical structure has different characteristics at each location at which force is applied and measuring location. The characteristics are different due to resonance frequency and antiresonance frequency. Antiresonance frequencies are determined by zero amplitude of dynamic behavior. Furthermore, their frequencies affect the control stability. This paper presents a method to distinguish between control stability and instability of the linear slider mechanism. In this method, control stability is distinguished to calculate the damping value of a multi-degree-of-freedom mechanism with control. Control algorithms are applied to positive acceleration feedback control and negative velocity feedback control.