推定負荷情報に基づく二慣性共振系のロバスト位置制御系の一設計法

This paper proposes a new robust load position servo system without mechanical vibration and end-effector offset for industrial robots. The compact high-gear reduction without backlash, such as the harmonic gear is frequently used in the driving system for the sake of high load-to-weight performance. Generally, the industrial robots have used the sensors mounted to actuator-side because hardware setting using load-side sensor is very hard to mount signal lines. Therefore, the end-effector response does not perfectly reach the desired position owing to the effect of external disturbance force, which is called end-effector offset. The proposed robust servo system uses the estimated load information due to repress the effect of external disturbance force. The proposed position servo system is designed based on the state & disturbance observer and robust speed control system using coprime factorization controller. The effectiveness of the proposed robust system is confirmed by experimental results of prototype mechanical system.

The antilock braking systems are designed to maximize wheel traction by preventing the wheels from locking during braking, while also maintaining adequate vehicle steerability; however, the performance is often degraded under harsh road conditions. In this study, a robust hybrid control system is developed for the antilock braking systems. In this design method, the robust hybrid control system is comprised of a hybrid controller and a robust controller to achieve a desired H/sup /spl infin// control performance. The hybrid controller containing a fuzzy uncertainty observer is the principal controller, and the robust controller is designed to achieve the desired H/sup /spl infin// tracking performance. Finally, simulations are performed to demonstrate the effectiveness of the proposed robust hybrid control system for antilock braking control under various road conditions.

This paper discusses an application of Robust Model Matching (RMM) to the spill position control of a fuel injection pump. Since the fuel injection servo mechanism is soaked in fuel oil, the parameters of the plant vary due to differences in the viscosity coefficient caused by wide changes in temperature. The invariable fuel injection characteristic is required to meet the demands of the drivability, exhaust emissions and fuel consumption, even though the parameters change. The RMM is an idea which makes up a robust control system against parameter uncertainties.In this paper, we design a robust discrete-time control system based on the RMM: (1) For the low sensitivity, to make small pulse transfer functions from equivalent disturbances to controlled variables. (2) For the robust stability, to increase the margin of pulse transfer functions from conceptual inputs to control variables. The experimental results show that this robust compensator makes up a robust control system against the parameter variations due to the change in temperature. And it is confirmed that the idea of the RMM is effective for the fuel injection pump which includes the variations, identification errors, friction, hysteresis and delay time of the calculation.

We propose a robust control system which has robustness for disturbance and can deal with a nonlinear system with partially unknown structure by fusing reinforcement learning and robust control theory. First, we solved an optimal control problem without using unknown part of functions of the system, using neural network and the repetition learning of reinforcement learning algorithm. Second, we built the robust reinforcement learning control system which permits uncertainty and has robustness for disturbance by fusing the idea of H infinity control theory with above system.

The issues of expediency of using adaptation tools in robust control systems are discussed. It is stated that purely robust systems without the use of adaptation tools, in principle, cannot provide high efficiency and versatility in solving practical problems. Robust control systems were originally conceived as non-adaptive systems (passive adaptive systems). In view of the emerging problems in solving practical problems, then a mutation occurred and works appeared under the name "Adaptive-robust systems", "Combined robust systems", etc., partially using adaptation algorithms. Setting the problem of control synthesis under conditions of uncertainty without elements of adaptation is figuratively speaking similar to "search for a black cat in a dark room, especially if it is not there" (Confucius). The most adequate from the point of view of compliance with the fundamental principles of the theory of automatic control is an approach based on an increase in the gain of an open loop. Nevertheless, here too a problem arises — an increase in the gain violates the stability of a closed system. All known research is concentrated around the solution of this problem. An integrated gain self-tuning algorithm and the corresponding circuitry and Simulink implementation scheme have been developed. The reliability of theoretical reasoning was verified by simulating a limiting robust system with self-tuning and a parametrically indeterminate object — "peak gyroscope (parametric pendulum)". Computer studies have made it possible to draw a number of positive conclusions that are of great practical importance.

This paper proposes a new robust feedforward tracking servo system for optical disk recording systems in the case of a sudden disturbance for the optical disk recording system. In optical recording systems, the tracking servo system must suppress tracking error below its tolerance. This paper designs the robust feedback control system by using the coprime factorization and disturbance observer. The proposed robust feedback control system suppresses the sudden disturbance caused by walking and running. The detecting signal of optical disk recording systems is only a tracking error. Hence, the feedforward controller of the proposed tracking control system is constructed based on both Zero Phase Error Tracking (ZPET) control theory and prediction of tracking error. The experimental results point out that the proposed tracking servo system has a quick and precise tracking response and keeps the residual tracking error below its tolerance. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(4): 60– 68, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20257

In this paper, controller performance of three kinds of robust control systems which are Disturbance Observer, Sliding Mode Control (SMC) and H∞ control are evaluated, when they are applied to positioning control of electrical hydraulic servo system.We propose several evaluation methods and standard of design considering characteristic of electrical hydraulic system, and decide system parameters for each robust control systems according to the several standard of design. Next, we apply them to actual electrical hydraulic servo system, and evaluate the difference of control performance from the point of view of robustness for parameter variations, characteristic of disturbance cancellation and control input. As a result, all of them has shown good robustness, but H∞ control shows worse performance in characteristic of disturbance cancellation and control input than other control systems.

For field tasks, it is quite challenged to operate in a complex environment for the underwater robots, especially for those with multiple control surfaces due to different response and gain characteristics. To this end, this paper develops a highly integrated robotic dolphin followed by a robust motion control system. For better maneuverability and fault-tolerant capabilities, a newly-designed robotic dolphin is presented, owning a wide array of sensors and multiple control surfaces, in which passive flukes are particularly applied. On this basis, a robust motion control system is proposed, including a depth controller based on velocity-related allocation strategies and a heading controller based on clearance compensation. In detail, considering the degradation of motion performance caused by passive flukes, a sliding mode controller for gain uncertainty and an allocation-related parameter tuning strategy for inputs response characteristics are designed. Extensive simulations and aquatic experiments are conducted, and the obtained results demonstrate the satisfied maneuverability of the designed prototype and the effectiveness of the proposed methods. This study can lay a foundation for further development of robotic dolphins with a robust motion system to execute complex tasks in the field. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —This paper is inspired by the issue of robust motion control system for a newly-designed practical robotic dolphin that possesses a passive tail and redundant control surfaces. The traditional methods are usually susceptible to uncertainties in the passive tail gain, exhibiting degraded control performance. Moreover, control oscillations and slow convergence speed often occur caused by neglecting the characteristics of different control surfaces, including response patterns and clearance. This paper suggests a robust depth controller based on velocity-related allocation strategies and a robust heading controller based on clearance compensation. Specifically, an allocation-related parameter tuning strategy is given by considering inputs response characteristics, including response speed, saturations, and hydrodynamic force variation patterns. To guarantee fine regulations of heading control, a nonlinear disturbance observer (NDOB)-based clearance compensation is proposed. Extensive aquatic experiments on the newly-designed robotic dolphin verified the effectiveness of the proposed methods. It is envisioned that all these presented results can provide valuable engineering practice insights for industry practitioners.

Rotorcraft flight control systems present design challenges which often exceed those associated with fixed-wing aircraft. First, large variations in the response characteristics of rotorcraft result from the wide range of airspeeds of typical operation (hover to over 100 kts). Second, the assumption of vehicle rigidity often employed in the design of fixed-wing flight control systems is rarely justified in rotorcraft where rotor degrees of freedom can have a significant impact on the system performance and stability. Proposed herein is a methodology for the design of robust rotorcraft flight control systems utilizing Quantitative Feedback Theory (QFI'), a technique which accounts for variability in the dynamic response of the controlled element in the design of robust control systems. It was developed to address a Multiple-Input-Single-Output (MISO) design problem, but was extended to the address the Multiple-Input-Multiple-Output (MIMO) flight control system (FCS) design problem of a UH-60 Black Hawk Helicopter. Inherent conservatism in this design technique leads to limitations in its utility. A modified QFI' approach proved a viable method for designing robust MIMO flight control systems. An analysis of the two flight control system design methodologies is presented.

In this paper, we overview the design and development of robust multivariable control design to highlight some of the pragmatic automotive engineering control issues with an emphasis on a non-trivial application of Hybrid Electric Vehicle (HEV) Torque Management. We shall outline that most existing torque management approaches are not model-based dynamical systems, or do not address key concepts of robust stability and performance. We shall also discuss some advantages that robust control systems could offer to a wider automotive control applications. In part II, we show representative simulation results verifying that robust control systems design could be a breakthrough to the production of hybrid electric vehicles by yielding significant improvements on the emission, fuel consumption, calibration time and cost. Our contribution is aimed at the fact that cutting-edge robust controllers could be broadly adopted to tackle increasingly challenging problems of the automotive industry.

In the paper, the impact of atmospheric turbulence on the Unmanned Aerial Vehicles (UAV) motion is studied. The models of Dryden turbulence are discussed, and the airplane models of lateral directional under the atmospheric turbulence are deducted, the application of linear matrix inequality (LMI) is used to design a kind of robust flight control system based on H∞ control theory. The effect of the roll angle control of Robust flight controller is compared to that of PID controller and several characteristics of the state points in full-flight envelope are selected to validate the robust flight control system. The analysis shows that the designed controller is better than PID controller to attenuate the disturbance, and the flight control system has good dynamic performance and satisfactory robustness.

Robust control of a SAG mill

In earlier papers, it has been reported that a fast and precise servo system, which has low sensitivity to parameter variation and disturbance, can be realized with simple structure by using a high-order disturbance observer. However, no clear and simple design method satisfying specifications for robust stability, the influence of measurement noise, and relative stability (damping characteristics) for large parameter variation has been proposed. In this paper, we clarify the class of robust servo systems realized by adjusting the order of the disturbance observer and the control parameters. We apply this strategy to the design of a second delay system, such as a position servo system, and realize a high-performance robust servo system using a high-order disturbance observer. © 1999 Scripta Technica, Electr Eng Jpn, 128(1): 37–44, 1999

This paper presents a control scheme designed for Brushless DC Motor (BLDCM) drive. The proposed scheme is fed by Indirect Matrix Converter (IMC). The IMC works as an AC-AC power supply for BLDCM. The scheme includes speed servo system and position servo system. Firstly, the advantages and working principles of IMC are introduced, showing that IMC is a superior power converter. Then, the IMC-fed BLDCM servo system is designed. The command speed or command position for BLDCM could be tracked accurately and respectively. In the position servo system, a fuzzy P controller is employed as the position regulator. From the simulation results, it is illustrated that IMC-fed BLDCM servo system has satisfed performance of tracking the command speed or command position.KeywordsIMCBLDCMservofuzzy P controller

This paper proposes a sliding mode control with a disturbance estimation for an underwater robot. The mobility performance of an underwater robot is influenced by modeling error, observation noise, and several disturbances such as ocean current and tidal current. Therefore, a robust control system is needed for precise motion control of an underwater robot. This paper uses a sliding mode control, which is one of the robust control methods. In a sliding mode control, chattering tends to occur, if the switching gain is set to a high value. On the other hand, it is desirable to set the switching gain high from the viewpoint of robustness. Therefore, there is a trade-off between the switching gain and robustness. In the proposed method, the disturbance is estimated in real-time, and this estimated value is added to the control input. Most of the disturbances are compensated by this estimated value, and the sliding mode control is used for the rest of the disturbances. As a result, the robust control system is achieved by using the proposed method, even if the switching gain is set to a low value. The validity of the proposed method was confirmed from the simulation and experimental results.