Conventional Control Law Research Articles

A Variable-Sampling Controller for Brushless DC Motor Drives With Low-Resolution Position Sensors

This paper proposes a variable-sampling variable structure controller (VSC) for brushless dc (BLDC) motor drives with low-resolution position sensors (Hall sensors). The variable-sampling characteristics arising from the situation where measurements depend on the path-embedded sensors will result in the uncertainty of the discrete-time models. To circumvent this issue, a modification of the conventional discrete-time VSC control law for BLDC motor drives with Hall sensors is derived to achieve the robustness of speed control. Three measurement error-mitigation methods are also presented to reduce the errors due to low-resolution position feedback. Both simulated and experimental results confirm the effectiveness of the proposed controller and error-mitigation techniques.

퍼지 관측기와 퍼지 가변구조제어를 이용한 천정주행 크레인의 적응형 흔들림 억제 궤적추종제어

Adaptive anti-sway and trajectory tracking control of overhead crane is presented, which utilizes Fuzzy Uncertainty Observer(FUO) and Fuzzy based Variable Structure Control(FVSC). We consider an overhead crane system which can be decoupled into the actuated and unactuated subsystems with its own lumped uncertainty such as parameter uncertainties and external disturbance. First, a new method for anti-sway control using FVSC is proposed to improve the conventional method based on Lyapunov direct method, while a conventional trajectory tracking control law using feedback linearization is directly adopted. Second, FUO is designed to estimate one of the two lumped uncertainties which can compensate both of them, based on the fact that two lumped uncertainties are coupled with each other. Then, an adaptive anti-sway control is proposed by incorporating the proposed FVSC and FUO. Under the condition that the observation error is Uniformly Ultimately Bounded(UUB) within an arbitrarily shrinkable region, the overall closed-loop system is shown to be Globally Uniformly Ultimately Bounded(GUUB). In addition, the Global Asymptotic Stability(GAS) of it is shown under the vanishing disturbance assumption. Finally, the effectiveness of the proposed scheme has been confirmed by numerical simulations.

Effect of Wheel-Slip Prevention Control Using Nonlinear Robust Control Theory

It is important to consider robustness when design of brake control systems, because there are the model's uncertainties which result from nonlinear characteristics of adhesion forces between wheel and rail, and friction coefficients of brake materials. This paper presents the experimental results about the new wheel-slip prevention control using nonlinear robust control theory. The authors performed experiments for the proposed wheel-slip prevention control to compare it with the conventional control laws. The experimental results proved the comparative effectiveness of the proposed control and showed high brake performances under nonlinear characteristics of brake dynamics.

Modelling and Simulation of a Hybrid Vehicle Using Direct Torque Control of Induction Motor

The authors develop and present a new model of a hybrid vehicle and control strategy. The hybrid vehicle is a general class of vehicles in which the prime power and the driveline are decoupled. The configuration considered in this paper consists of a diesel engine driving a permanent magnet generator that supplies rectified power to a DC link, which in turn supplies power through an inverter to an induction motor for traction. The control system proposed is hierarchical with controllers at the component, subsystem, and system level. Direct torque control (DTC) algorithm is applied to control the induction motor. The subsystem controllers consist of feedback control loops encompassing sliding mode, bang-bang, and conventional control laws. At the system level, a logic controller balances source and loads on the system bus. All models and controllers are simulated using MATLAB and SIMULINK computer program. The performance and scalability of each subsystem controller is demonstrated in stand-alone computer simulations. The modelling and control strategy proposed in this paper provides a robust, scalable system model for simulating the effects of standard driving cycles on the power system of a given vehicle configuration over long time scales.

LATERAL CONTROL WITH IMPROVED PERFORMANCE FOR UAVs

This paper presents conventional proportional and derivative lateral control law with some non-linear modifications which enhance tracking performance for a UAV in different flight conditions especially recovery from large cross track errors. The scheme was implemented in C/C++ and extensively tested in 6-DoF nonlinear simulation environment. The performance was also compared with recent nonlinear lateral control logic (Park, 2004) on straight and circular paths. Simulation results showed that proposed scheme gave comparable path tracking performance with nonlinear logic on circular trajectories along with improved performance on straight paths with smaller steady state errors.

トルクユニットマニピュレータの全状態変数を制御するための運動軌道に関する考察

A new design concept of space manipulator has been proposed, which is called Torque-unit Manipulator (TUM) . Each joint of TUM is free and a device which is called “torque unit” is equipped on each link. The “torque unit” can be made easily of a DC motor and a disc, for example. Position-controllability of the links of TUM has been shown with conventional control laws for manipulators, however some of state variables cannot be controlled when such control laws are used. When such control laws are used, positions of the links are controlled to desired positions but the angular velocities of the discs usually do not come to zero and result to be constant. The reason is that TUM is a kind of nonholonomic system and hence the angular velocity of each disc at each time depends on the trajectories of the links. In this paper, a progress is made in the study of trajectory planning for 2-dimensional N d.o.f. TUM to control the positions of the links and the angular velocities of the discs. A possibility is considered to control the position of each link to desired position and the angular velocity of each disc to desired constant value which is not zero.

Sexuality and School Shootings

Conventional explanationslax gun control laws, media violence, single and working parentsdo not adequately explain the recent spate of school shootings, and neither does bullying by itself, an explanation recently gaining more traction. A certain type of bullying, however, is revealed as particularly culpable. Many of the recent shootings share a disturbing component: The perpetrators were repeatedly, even relentlessly, accused by “preps and jocks” of being gay. Gay harassment is proposed as a point of departure for understanding the causes of school shootings. When boys who believe on some level that they warrant privilege, are instead harassed, they may feel driven to avenge the “wrong,” and re-assert a more dominant, powerful, and victorious masculinity. These circumstances call for a cultural transformation such that “boys will be boys” is no longer used as an alibi for violence. The author presents implications for school-based social work practice, teacher and administrator interventions, as well as other prevention strategies.

Wheel Slip Prevention Control based on Nonlinear Robust Control Theory

In order to operate trains efficiently at high speeds regardless of their length, control systems that can provide stable braking forces must be developed. In the designing brake control systems, it is essential to consider the robustness because there are model uncertainties that result from nonlinear characteristics for adhesion and the brake material friction coefficient. This paper presents an innovative new wheel slip prevention control system that utilizes sliding mode control. Simulations for the proposed wheel slip prevention control system are performed and compared with some conventional control laws. The results of simulation prove the effectiveness of the proposed control system as compared with conventional types, and show the high brake performance under non-linearity of brake dynamics.

鉄道車両の車輪滑走防止のためのスライディングモード制御（実物大試験機を用いた制御実験）

In order to operate a train efficiently at high speeds regardless of the number of composed vehicles, control systems that can provide stable braking forces must be developed. In the design of brake control system, it is quite important to consider robustness because there are model uncertainties which result from nonlinear characteristics for adhesion between the wheel and rail, and the friction coefficients of brake materials. This paper will present the experimental results about the new wheel slip control, designed by the sliding mode control theory. The experiments for the proposed wheel slip control are performed while comparing some conventional control laws. The experimental results proved the effectiveness of the proposed control as compared with conventional ones, and showed the high brake performance under the nonlinear characteristics of brake dynamics.

スライディングモード制御理論に基づいた鉄道車両の滑走制御

In order to operate a train efficiently at high speeds, regardless of the number of vehicles involved, control systems that can provide stable braking forces must be developed. When designing brake control systems, it is quite important to consider robustness, because there are model uncertainties which a result from nonlinear characteristics for the adhesion and friction coefficients, of brake materials. In this paper, a new type of wheel slip prevention control, using sliding mode control, will be presented. Simulations for the proposed wheel slip prevention control are performed, while comparing some conventional control laws. The simulation results prove the effectiveness of the proposed control compared with conventional equivalents,and show high braking performance under nonlinearity of brake dynamics.

Control of a Permanent Magnet Synchronous Motor Using a Second-Order Non-Linear Trajectory Smoother

A second-order non-linear discrete trajectory smoother is coupled with conventional control law for servo-control of permanent magnet synchronous motors (PMSMs). Conventional control relies on three closed loops with linear proportional-integral-derivative (PID) controllers and gives an undesirable performance under the mismatch. of system parameters and load conditions. To overcome this drawback, a discrete-time second-order non-linear trajectory smoother is applied for the control of a PMSM. The second-order non-linear trajectory smoother is a non-linear variable structure system (VSS) catering for smooth trajectory generation for a motion control system. The trajectory smoother guarantees robustness against a change of system parameters and load conditions. Simulation and experimental studies are included to demonstrate the effectiveness of the proposed control scheme.

Design of a gain-scheduling mechanism for flight control laws by fuzzy clustering

The use of a linear design technique in combination with gain scheduling is the most common systematic approach to the design of nonlinear flight control laws. However, the selection of the operating points and the design of the interpolation scheme remains a time-consuming procedure. In order to reduce the design effort, an automated procedure has been developed and applied to the design of a longitudinal control law in a fly-by-wire flight control system. The number of operating points and their locations are determined automatically by using fuzzy clustering to capture characteristic patterns in the aerodynamic model throughout the flight envelope. This approach also directly provides the interpolation mechanism (membership functions) for the local flight control law parameters. The design procedure has been developed in close cooperation with airframe and control system manufacturers and was evaluated through pilot-in-the-loop flight simulator tests. Experienced test pilots could not detect any significant difference between the conventional flight control laws and those implemented with fuzzy gain scheduling, even though the latter used fewer operating points and was designed in an automated manner, as opposed to the conventional iterative manual procedure.

Design of the impact controlling structure applying conventional digital control laws

The design of a simplified IMPACT (Internal Model Principle and Control Together) structure comprising conventional digital control laws is presented. The design procedure is accomplished to enable the extraction of a known class of immeasurable external disturbances and easy setting of the controller parameters. In the proposed controlling structure, the set point transient response and speed of disturbance rejection can be adjusted independently. The efficiency and robustness of the proposed controlling structure are verified and tested by the simulation and experimental setup.

Disturbance attenuation and rejection for systems with nonlinearity via DOBC approach

In this paper the disturbance attenuation and rejection problem is investigated for a class of MIMO nonlinear systems in the disturbance-observer-based control (DOBC) framework. The unknown external disturbances are supposed to be generated by an exogenous system, where some classic assumptions on disturbances can be removed. Two kinds of nonlinear dynamics in the plants are considered, respectively, which correspond to the known and unknown functions. Design schemes are presented for both the full-order and reduced-order disturbance observers via LMI-based algorithms. For the plants with known nonlinearity, it is shown that the full-order observer can be constructed by augmenting the estimation of disturbances into the full-state estimation, and the reduced-order ones can be designed by using of the separation principle. For the uncertain nonlinearity, the problem can be reduced to a robust observer design problem. By integrating the disturbance observers with conventional control laws, the disturbances can be rejected and the desired dynamic performances can be guaranteed. If the disturbance also has perturbations, it is shown that the proposed approaches are infeasible and further research is required in the future. Finally, simulations for a flight control system is given to demonstrate the effectiveness of the results. Copyright © 2005 John Wiley & Sons, Ltd.

Coordinated attitude control for a tracking and data relay satellite with mobile antennas

In this paper, a coordinated attitude control law for a tracking and data relay satellite (TDRS) with mobile antennas is proposed. To track or point the target spacecraft with median/law orbit, the large mobile antennas have to move in a wide range, the movement of such mobile antennas disturbing the satellite attitude. Conventionally, the main body of the satellite and the mobile antennas are controlled independently. The proposed controller first estimates the TDRS's angular momentum which the mobile antennas will produce, based on the momentum conservation equation, then adds the estimated angular momentum as a feedforward signal to the conventional control law. The proposed controller is demonstrated using mathematical simulation, the results of which coincide well with analytical results.

Robust Control of Master-Slave Manipulator Systems in Consideration of Actuator Dynamics and Uncertainty for Objects and Operator

This paper proposes a design method of a robust control system for electrically-driven master-slave manipulator systems taking actuator dynamics and uncertainty of objects and operator into consideration. Based on the backstepping technique, conventional control law for the master-slave manipulator systems is extended so as to satisfy passivity of the whole systems including actuator dynamics in the presence of uncertainty for the object and the operator under some assumptions. The proposed control scheme showed superior maneuverability compared with the conventional control scheme through the experimental works.

Non-linear control design for a boost converter using bond graphs

The bond graph technique is applied to model a boost converter in order to derive an averaged model. The obtained averaged model is non-ideal as it takes into account most of the converter non-linearities introduced by power semiconductor devices. An ideal averaged model of the converter can be deduced easily for computing a non-linear control law in a real-time control context. The current-mode control of the boost converter is considered. The zero dynamics are studied by both classical theory and the bond graph approach. A modified version of a conventional nonlinear control law is proposed in order to improve the dynamic behaviour and to reduce the sensitivity to control model errors. The non-ideal averaged model is used firstly for simulation analyses of the proposed control law and then for comparison with experimental results.

Non-linear control design for a boost converter using bond graphs

The bond graph technique is applied to model a boost converter in order to derive an averaged model. The obtained averaged model is non-ideal as it takes into account most of the converter non-linearities introduced by power semiconductor devices. An ideal averaged model of the converter can be deduced easily for computing a non-linear control law in a real-time control context. The current-mode control of the boost converter is considered. The zero dynamics are studied by both classical theory and the bond graph approach. A modified version of a conventional nonlinear control law is proposed in order to improve the dynamic behaviour and to reduce the sensitivity to control model errors. The non-ideal averaged model is used firstly for simulation analyses of the proposed control law and then for comparison with experimental results.

Optimal Control of Fruit Responses during Storage as Affected by Temperature

Lower temperature is usually effective to reduce the quality loss of fruits during storage. It is, however, difficult to accomplish the qualitative improvement of the fruit by only the low temperature. In this study, a more effective control technique for temperature that minimizes the water loss and respiration of the fruit was explored using intelligent approaches. The control input is the storage temperature, and the control outputs are two fruit responses (the water loss and respiration rates). A decision system consisting of neural networks and genetic algorithms allowed an optimal value (8-step set points of temperatures) to be successfully determined. Under the range of 15 to 40°C, an optimal value was the combination of the highest temperature and the lowest, like a (40, 40, 15, 15, 15, 15, 15 and 15°C). Especially, a temperature operation that first raises to the high level and then drops to the lowest level in the given range significantly reduced the water loss and respiration of the fruit, and their values became lower than those in the case of maintaining at the lowest and constant level. Under the range of 5 to 40°C, however, it was the combination of only the lowest temperatures. This operation is the same as a conventional cold-storage manner. These results suggest that a flexible control of the environment based on the fruit responses is better than a conventional constant-value control law in order to maintain the fruit quality.

Comparison of Intelligent, Adaptive, and Nonlinear Flight Control Laws

Seven different nonlinear control laws for multiaxis control of a high-performance aircraft are compared in simulation. The control law approaches are fuzzy logic control, backstepping adaptive control, neural network augmented control, variable structure control, and indirect adaptive versions of model predictive control and dynamic inversion. In addition, a more conventional scheduled dynamic inversion control law is used as a baseline. In some of the cases, a stochastic genetic algorithm was used to optimize e xed parameters during design. The control laws are demonstrated on a six-degree-of-freedom simulation with nonlinear aerodynamic and engine models, actuator models with position and rate saturations, and turbulence. Simulation results include a variety of single- and multiple-axis maneuvers in normal operation and with failures or damage. The specie c failure and damage cases that are examined include single and multiple lost surfaces, actuator hardovers, and an oscillating stabilatorcase. Therearealso substantial differences between thecontrol law design and simulation models,which are used to demonstrate some robustness aspects of the different control laws.