Department of Electrical Engineering

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IIT Jodhpur

This paper presents a novel lateral series microwave switch fabricated on a silicon-on-insulator (SOI) substrate with a finite ground coplanar waveguide (FGCPW) configuration which is laterally actuated by the electrostatic force. The switch is built with a cantilever beam in the direction of the signal line and a fixed electrode is located opposite the cantilever beam. The mechanical structures are fabricated using SOI deep reactive ion etching (DRIE) and shadow mask technology. The fabricated lateral RF MEMS switch has an isolation of 16 dB at 20 GHz. The insertion loss of the switch is 1 dB and return loss is 15 dB at 20 GHz. The threshold voltage is 19.2 V and switching time is 30 μs.

World University root node

Analog Integrated Circuits and Signal Processing

A new approach of lateral RF MEMS switch

This paper discusses the spatial controller design with periodic output feedback for a 540 MWe PHWR. the spatial model of the reactor developed in (Tiwari, 1999) is augmented with models for variation of coolant and fuel temperatures to form a 72 order model. This new model having 14 inputs and 29 outputs, is suitably reduced by aggregation method. Finally, a periodic output feedback control for the high order model is designed using the reduced model. the results of nonlinear simulations are presented. Copyright © 2004 IFAC

IFAC Proceedings Volumes (IFAC-PapersOnline)

Spatial control of a large PHWR by periodic output feedback and model reduction

Power System Stabilizers (PSSs) are added to excitation systems to enhance the damping during low frequency oscillations. In this paper, the design of decentralized PSSs for 10 machines with 39 buses using fast output sampling feedback via reduced order model is proposed. The nonlinear model of multimachine system is linearized at a particular operating point and a linear model is obtained. Using model reduction technique, lower order model is obtained from the higher order model and for this reduced model a stabilizing state feedback gain is obtained. Using aggregation technique, state feedback gain is obtained for the higher order model. A decentralized fast output sampling feedback gain which realizes this state feedback gain is obtained using LMI approach. This method does not require state of the system for feedback and is easily implementable. This decentralized fast output sampling control via reduced order model is applied to non-linear plant model of the multimachine. This method gives very good results for the design of Power System Stabilizers.

2004 5th Asian Control Conference

Design of decentralized power system stabilizers for multimachine power system using model reduction and fast output sampling techniques

This paper presents an output feedback based discrete-time sliding mode control strategy using the concept of a PdRd sliding sector. The resulting control is based on the system output and immediate past control input and is independent of the system states. It ensures that the norm of the system states decreases monotonically and continue to do so even with a zero input inside the designed sliding sector. Copyright © 2004 IFAC.

Multirate output feedback discrete-time sliding mode control for a prescribed sliding sector

The purpose of this letter Is to show that the recently proposed fast output sampling sliding-mode control method in an earlier paper by the authors needs a small correction in the expression for the control law. The results of the corrected algorithm is illustrated by the same example considered in the earlier paper.

IEEE Transactions on Industrial Electronics

A Minor Correction to "A New Algorithm for Discrete-Time Sliding Mode Control Using Fast Output Sampling Feedback"

The aim of this paper is to develop a new method for sliding mode control of a class of discrete-time nonlinear systems that are feedback linearizable. One advantage of this method is that it allows the use of the recently developed output feedback sliding mode control strategy for linear systems to a class of nonlinear systems. The second advantage of this approach is that it can be used in situations where complete state information is not available or the use of dynamic compensator becomes essential. Copyright © 2004 IFAC.

Discrete sliding mode control for nonlinear systems using feedback linearization

In this paper, a single-pole double-throw (SPDT) switching circuit that employs lateral metal-contact micromachined switches fabricated or silieon-on-insulator (SOI) wafer is demonstrated to operate from DC to 6 GHz. The size of the fabricated SPDT switch is about 1.2 mm × 1.5 mm. The lateral metal-contact micromnchined switches are formed on the quasi-finite ground coplanar waveguide (FGCPW) transmission lines and actuated by electrostatic force. The fabricated single-pole single-throw (SPST) lateral micromachined switch has an insertion loss of 0.2 dB and a return loss of 24 dB at 15 GHz. The isolation is 23 dB at 15 GHz. As for the fabricated SPDT switch, the measured insertion loss is below 0.75 dB and the return loss is higher than 19 dB at 5 GHz. The isolation at 5 GHz is above 33 dB. The threshold voltage of these switches is 22.5 volts, and these SOI switches are fabricated using deep reactive ion etching (DME) and shadow mask technology.

IEEE MTT-S International Microwave Symposium Digest

A single-pole double-throw (SPDT) circuit using deep etching lateral metal-contact switches

Active vibration control is an important problem in structures. One of the ways to tackle this problem is to make the structure smart, adaptive and self-controlling. The objective of active vibration control is to reduce the vibration of a system by automatic modification of the system's structural response. This work features the modeling and design of a Periodic Output Feedback (POP) control technique for the vibration control of a smart flexible cantilever beam system for a Single Input Single Output case. A POP controller is designed for the beam by bonding patches of piezoelectric layer as sensor/actuator to the master structure at different locations along the length of the beam. The entire structure is modeled in state space form using the Finite Element Method by dividing the structure into 3, 4, 5 elements, thus giving rise to three types of systems, viz., system 1 (beam divided into 3 finite elements), system 2 (4 finite elements), system 3 (5 finite elements). The smart cantilever beam model is developed using the concept of piezoelectric bonding and Euler-Bernouli theory principles. The effect of placing the sensor/actuator at various locations along the length of the beam for all the three types of systems considered is observed and the conclusions are drawn for the best performance and for the smallest magnitude of the control input required to control the vibrations of the beam.

Asian Journal of Control

Vibration control of a smart structure using periodic output feedback technique

The paper presents an algorithm for the discrete-time output feedback sliding mode control of time delayed systems with uncertainty. The proposed algorithm is capable of handling systems with both state and input delay. The major advantage of the algorithm is that it is based on system output and hence more practical. Moreover, it reduces chattering by avoiding the usage of a switching input. © 2004 IEEE.

Proceedings of the IEEE International Conference on Control Applications

Discrete-time output feedback sliding mode control for time-delay systems with uncertainty

The present work attempts to utilize the fast output sampling control law for a completely new application: the autopilot controller design for practical launch vehicle systems. Linearized models representing different launch stages (with inclusion of vehicle flexibility, fuel sloshing effects, nozzle dynamics and actuator dynamics) have been used. The design problem is transformed into an equivalent Linear Matrix Inequality (LMI) form to realize a state feedback approximately by fast output sampling, in a way that closeness to the original design can be traded against reducing the deteriorating effects. Output stabilization is achieved with satisfactory results. © 2004 IEEE.