G. Chakraborty

Robust Unknown Input Observer for Nonlinear Systems and Its Application to Fault Detection and Isolation

A robust unknown input observer for a nonlinear system whose nonlinear function satisfies the Lipschitz condition is designed based on linear matrix inequality approach. Both noise and uncertainties are taken into account in deriving the observer. A component fault detection and isolation scheme based on these observers is proposed. The effectiveness of the observer and the fault diagnosis scheme is shown by applying them for component fault diagnosis of an electrohydraulic actuator.

Unknown input nonlinear observer for component fault detection and isolation of dynamic systems

A full order unknown input nonlinear observer is presented. The observer is designed for nonlinear systems whose nonlinear function satisfies Lipschitz condition. A component Fault Detection and Isolation (FDI) scheme is then devised using this observer. The FDI algorithm consists of two steps. In Step 1, the detection of fault and the partial isolation of fault are performed. In Step 2, the total isolation of fault is completed. The FDI scheme is used to detect and isolate fault in a mechanical system.

A modular approach to detailed dynamic formulation and control of wheeled mobile robot

Presently, nonholonomic mobile robots driven by wheels are being used for variety of applications where high velocity maneuvering control is very essential. The need for accurate formulation of system dynamics incorporating each & every moving parts of the robot is very important for faster movement & precise applications. This paper represents the detailed dynamic formulation based on overall robots kinetic energy along with an advanced control scheme. Actuator dynamics have been also considered to achieve precise motion control and to design a simple controller with a low cost sensor suite. A modular approach has been adopted to derive the kinetic energy of the robot accurately & thereafter to evaluate required equations of motion. A feedback linearization based path following controller with online gain scheduling has been designed to control the mobile robot through various paths. The methodology adopted for path following control deals explicitly with detail robot-actuator dynamics and it overcomes stringent initial condition constraints. The simulation has been carried out with the parameters of a real robot and the simulation results illustrate very promising performance due to incorporation of detail robot-actuator dynamics.

An unknown input Kalman filter based component FDI algorithm and its application in automobiles

An Unknown Input Kalman Filter (UIKF) based Component Fault Detection and Isolation (CFDI) technique for a dynamical system, affected by both plant and measurement noise, is presented. The Fault Detection and Isolation (FDI) algorithm, which consists of two steps, is developed with the assumption that the fault occurs in a single component of the system. In step 1, the detection of the fault and the isolation of the faulty region are achieved. In the next step, the faulty parameter is isolated from the faulty region. The method is applied on a road vehicle model to show the effectiveness of the algorithm.

On Rolling Resistance in Gear Transmission

The effect of rolling resistance on the power loss during gear transmission has been studied. The resistance has been modeled by a lateral shift of the line of action of the contact force. The effect of this shift on the equivalent friction force has been predicted with the help of a six degrees of freedom (DOF) model of a spur gear pair. The predicted results agree closely with the experimental data available in literature.

Study on the Delamination of GFRP Composites in Drilling: A Finite Element Model

Glass fiber reinforced plastics (GFRP) is an important class of materials due to its high strength-to-weight ratio. Delamination during drilling of GFRP composites reduces the strength of the components considerably, and the components may fail to meet the requirements. Very less work is reported on finite element (FE) studies on delamination while drilling of FRP composites. The nonhomogeneous and anisotropic nature of the work material complex oblique cutting process are the major difficulties for the FEM study. In this work, FE model using ABAQUS 6.10 is developed for drilling of GFRP composites using conventional twist drill. A “VUSDFLD” subroutine for ABAQUS 6.10/Explicit is written and incorporated with the material model during the simulation. Thrust force and torque obtained from simulation are compared with the experimental values reported in the literature. Good agreement between the simulation and experimental results was observed.

Fault detection and isolation of vehicle suspension system using robust unknown input observers

A method of Fault Detection and Isolation (FDI) for vehicle suspension systems in the presence of exogenous noise and parametric uncertainties is presented. First, a new kind of reduced-order Robust Unknown Input Observer (RUIO) is designed based on Linear Matrix Inequality (LMI) approach. Then, using a bank of such observers, a component FDI algorithm is derived. Simulation results with the help of half-car model show the efficacies of the FDI algorithm as well as the observer.