Key Engineering Materials Vol. 497

Abstract: In this paper, we examine a design method for control system to attenuate unknown inputand output disturbances using disturbance observers. The disturbance observers have been usedto estimate the disturbance in the plant. Several papers on design methods of disturbance observershave been published. Recently, parameterizations of all disturbance observers and all linear functionaldisturbance observers for plants with any input and output disturbances were clarified. If parameterizationsof all disturbance observers and all linear functional disturbance observers for any input andoutput disturbances are used, there is a possibility that we can design control systems to attenuate unknowninput and output disturbances effectively. However, no paper has examined a design methodfor control system using parameterizations of all disturbance observers and all linear functional disturbanceobservers for plants with any input and output disturbances. In this paper, in order to attenuateunknown input and output disturbances effectively, we propose a design method for control systemusing parameterizations of all disturbance observers and all linear functional disturbance observersfor plants with any input and output disturbances. In addition, control characteristics of the proposedcontrol system are clarified.

Abstract: Disturbance observers have been used to estimate the disturbance in the plant. Several paperson design methods of disturbance observers have been published. Recently, the parameterizationof all disturbance observers for discrete-time plants with any output disturbance was clarified. However,no paper examines the parameterization of all disturbance observers for discrete-time plants withany input disturbance. In this paper, we clarify existance conditions of a disturbance observer and ofa linear functional disturbance observer for discrete-time plants with any input disturbance. Underthese conditions, we propose parameterizations of all disturbance observers and all linear functionaldisturbance observers for discrete-time plants with any input disturbance.

Abstract: In the present paper, we examine the parameterization of all stabilizing Internal Model Controllers(IMC) for multiple-input/multiple-output unstable plant. The parameterization problem is theproblem in which all stabilizing controllers for a plant are sought [1, 2, 3, 4, 5, 6, 7, 8, 9]. Since this parameterizationcan successfully search for all proper stabilizing controllers, it is used as a tool for manycontrol problems. However, there exists a problem whether or not stabilizing controllers for unstableplant can be represented by IMC structure. The IMC structure has advantages such as closed-loop stabilityis assured simply by choosing a stable IMC parameter. Additionally, closed-loop performancecharacteristics are related directly to controller parameters, which makes on-line tuning of the IMCvery convenient[6]. The solution to this problem, Morari and Zafiriou[6] examined the parameterizationof all stabilizing IMC for unstable plant. Their parameterization remains difficulties. Their internalmodel is not necessarily proper. In addition, their parameterization includes improper IMC. In order toovercome these problems, Chen et al. proposed a design method for IMC for minimum-phase unstableplant[17]. However, the method proposed by Chen et al. cannot apply for multiple-input/multipleoutputunstable plant. Because many of actual plants are multiple-input/multiple-output plants, consideringfor multiple-input/multiple-output unstable plant is important. In this paper, we propose theparameterization of all proper stabilizing IMC for multiple-input/multiple-output unstable plant suchthat the IMC and the internal model are proper. In addition, we present an application of the result forcontroller design for multiple-input/multiple-output time-delay plant.

Abstract: The modified Smith predictor is well known as an effective time-delay compensator fora plant with large time-delays, and several papers on the modified Smith predictor have been published.Recently, the parameterization of all stabilizing modified Smith predictors for time-delay plantswas obtained by Yamada et al. But, their method cannot specify the input-output characteristic andthe feedback characteristic separately. From the practical point of view, it is desirable that the inputoutputcharacteristic and the feedback characteristic are specified separately. In this paper, we proposethe parameterization of all stabilizing two-degree-of-freedom modified Smith predictors for multipleinput/multiple-output time-delay plants.

Abstract: In the present paper, we examine model feedback control systems (MFCSs). Because MFCSis simple, the MFCS has been applied in many applications such as the trajectory control of robotmanipulators, serially connected water tanks, etc. The control structure of the MFCS is limited, butYamada and Moki reported about whether or not MFCS can represent all of the stabilizing controllersof a minimum phase plant. However, no research has been reported whether or not MFCS can representall of the stabilizing controllers of a non-minimum phase plant. The purpose of the present paper isto give a solution to the question as to whether or not all of the stabilizing controllers for a plantare expressible in the MFCS structure. The relation between MFCS and the parameterization of allstabilizing controllers for a class of non-minimum phase plants is shown. A simple design method tospecify control characteristics is also presented.

Abstract: In this paper, we examine the parameterization of all plants stabilized by a proportionalcontroller for multiple-input/multiple-output plant. A proportional controller is a kind of Proportional-Integral-Derivative (PID) controllers. PID controller structure is the most widely used one in industrialapplications. Recently, if stabilizing PID controllers for the plant exist, the parameterization of allstabilizing PID controllers has been considered. However, no paper examines the parameterizationof all plants stabilized by a PID controller. In this paper, we clarify the parameterization of all plantsstabilized by a proportional controller for multiple-input/multiple-output plant. In addition, we presentthe parameterization of all stabilizing proportional controllers for the plant stabilized by a proportionalcontroller.

Abstract: Multi-period repetitive controllers improve the disturbance attenuation characteristic of themodified repetitive control system that follows the periodic reference input with small steady stateerror. Recently, the parameterization of all stabilizing multi-period repetitive controllers was studied.However, when the parameterization of all stabilizing multi-period repetitive controllers is used, theinput-output characteristic and the feedback characteristic cannot be specified separately. From thepractical point of view, it is desirable to specify the input-output characteristic and the feedback characteristicseparately. In addition, the parameterization is useful to design stabilizing controllers. Fromthis view-point, the parameterization of all stabilizing two-degree-of-freedom multi-period repetitivecontrollers those can specify the input-output characteristic and the disturbance attenuation characteristicseparately was solved by Yamada et al. However, when we design a stabilizing two-degree-offreedommulti-period repetitive controllers using the parameterization proposed by Yamada et al, thefrequency characteristic of the control system cannot be settled so easily. From the practical point ofview, the frequency characteristic of the control systems are required to be easily settled. This problemcan be solved by obtaining the parameterization of all stabilizing two-degree-of-freedom multi-periodrepetitive controllers with the specified frequency characteristic. In this paper, we propose the parameterizationof all stabilizing two-degree-of-freedom multi-period repetitive controllers with thespecified frequency characteristic.

Abstract: This paper describes the analysis and design of digitally-controlled class-E power amplifiers, which are suitable for fine CMOS implementation. Two methods for implementing digitally-controlled class-E(-like) amplifiers have already been proposed: using NMOS switch arrays or digital PWM. In this paper we analyze the operation and efficiency of these methods, and then we propose combining them to achieve higher efficiency.

Abstract: This paper describes a bipolar output DC-DC converter that uses a single inductor for size andcost reduction. We propose a timing diagram for a charge pump circuit which generates the negative outputvoltage, and present its con guration, operation principle and simulation results. We also show that employingpseudo-continuous conduction mode improves cross-regulation between the two outputs.

Abstract: In this paper, we present a bandwidth-efficient partial-response signaling scheme for capacitivelycoupled chip-to-chip data transmission to increase data rate. Partial-response coding is knownas a technique that allows high-speed transmission while using a limited frequency bandwidth, by allowingcontrolled intersymbol interference (ISI). Analysis and circuit simulation results are presentedto show the impact of duobinary (1+D) and dicode (1-D) partial-response signaling for capacitivelycoupled interface.