Surekha Kamath

System Identification and H∞ Observer Design for TRMS

A dynamic model for the two-degree-of-freedom Twin Rotor MIMO System (TRMS) is extracted using a blackbox system identification technique. Its behaviour in certain aspects resembles that of a helicopter, with a significant cross coupling between longitudinal and lateral directional motions. Hence, it is an interesting identification and control problem. Using the extracted model an H∞ observer is designed which will estimate the states of the system in presence of worst case noise assumed to be impact on the system.

Medical imaging techniques and computer aided diagnostic approaches for the detection of breast cancer with an emphasis on thermography – a review

In this article, a study of various medical imaging modalities and survey of computer aided detection (CAD) approaches used for the detection of breast cancer are presented. Early breast cancer detection, is important as it can increase the rate of diagnosis, cure and survival of the affected women. Medical imaging techniques can detect early signs of breast cancer. They are also used to diagnose, stage breast cancer and guide treatments. This article explains the imaging procedure, analysis of images, benefits and limitations of standard medical imaging techniques such as mammography, ultrasound, magnetic resonance imaging, and thermography. Also some of modern imaging techniques are discussed here. Comparative study of mammography, ultrasound, thermography and magnetic resonance imaging describes the benefits of thermography in early detection of breast cancer. CAD provides a fast, reliable, and cost-effective second opinion to support doctors with the diagnostic management of breast cancer. This article reviews various CAD algorithms developed and studied for mammography, ultrasound and thermography. From the literature review, it is observed that accuracy of detection of breast abnormalities using CAD are decided by many factors, such as size of database, image quality, segmentation of region of interest, extracted features and classifiers used, etc.

Simulation Study on Closed Loop Control Algorithm of Type 1 Diabetes Mellitus Patients

Abstract It is challenging to maintain normoglycemic range of glucose concentration in type I diabetic patients. In this study H∞ control is applied for insulin delivery to prevent the hyperglycemic levels in a type I diabetic patient. From a control theory point of view, the blood glucose regulation problem is reformulated as a tracking one. A glucose tolerance curve (GTC) validated from several patients is used as reference model. Intra- and inter-patient variability poses a challenging task to control blood glucose concentration in diabetic patients. We develop a data based robust controller to control blood glucose concentration in type I diabetic (TIDM) patients in the presence of meal disturbances under patient—model mismatch. Simulation studies are performed on the diabetic patient model under feedback control. It is seen that the proposed control strategy is able to control blood glucose concentration well within the acceptable limits and also compensate for slow parametric drifts.

Reliable H infinity observer-controller design for sensor and actuator failure in TRMS

Safety critical control systems are used in situations where the failure of a control system due to sensor failure or actuator failure will lead to a loss of life, property or cause environmental harm. A helicopter system really needs a safety critical or reliable control system which faces a lot of turbulent conditions and is expected to perform well, being stable in the case of sensor or/and actuator failures. Also the helicopter system is difficult to model mathematically due to non- linearity and cross coupling. The Twin Rotor MIMO System (TRMS) resembles the helicopter system in behaviour with significant cross coupling between the longitudinal and lateral axes. In this paper an H infinity observer and H infinity controller for a Twin Rotor MIMO System is aimed to be designed which will be reliable in the case of sensor failure or actuator failure also in case of sensor failure and actuator failure.

Implementation of reliable H infinity observer-controller for TRMS with sensor and actuator failure

In this paper reliable H infinity observer and H infinity controller which is designed for Twin Rotor MIMO System(TRMS) is implemented on real Twin Rotor MIMO System. The reliability of the observer-controller is tested on real TRMS with sensor and actuator partial failure and with complete failure. The model used is the identified model for TRMS using system identification technique.

Simulation Study on Type I Diabetic Patient

Abstract Maintaining glucose concentration in normoglycemic range in Type I diabetic patients is challenging. In this study H∞ control is applied for insulin delivery to prevent hyperglycemic levels in a type I diabetic patient. From a control theory point of view, the blood glucose regulation problem is reformulated as a tracking one. A glucose tolerance curve (GTC) validated from several patients is used as a reference model. Intra-and inter-patient variability poses a challenging task to control blood glucose concentration in diabetic patients. A data based robust controller is developed to control blood glucose concentration in type I diabetic patients in the presence of meal disturbances under patient-model mismatch. Simulation studies are performed on the diabetic patient model under feedback control which revealed that the proposed control strategy is able to control blood glucose concentration well within the acceptable limits and also compensate for slow parametric drifts.

Comparitive Study of Bergman and Augmented Minimal Model with Conventional Controller for Type 1 Diabetes

Diabetes - a global disease is spreading worldwide at an alarming rate. According to World Health Organization (WHO), the number of people suffering from diabetes has become four times in the last three decades. Therefore, monitoring and controlling diabetes has become of major concern lately. This paper focuses on the comparison of Diabetic minimal model (Bergman model) and Augmented minimal model for patients suffering from Type 1 diabetes. The focus will be on developing both the models on Simulink and comparing them to find the best results for regulation of insulin and glucose levels inside the body. Further, we also aim to develop a controller for both the models and tune the parameters for effective output. It is then observed that augmented minimal model shows better response.

Texture analysis of breast thermograms using neighbourhood grey tone difference matrix

Breast cancer is the leading cancer in women worldwide. Early detection can reduce the mortality rate of breast cancer. Breast thermography is a non-invasive and simple imaging technique used for early detection of breast cancer. Feature extraction and selection of appropriate features play a major role in computer-aided detection of breast cancer using breast thermograms. In this article, texture features are extracted from automatically segmented breast thermograms by computing neighbourhood grey tone difference matrix (NGTDM) and run length matrix (RLM). Significance of these features in differentiating the abnormal breast from the normal breast is found by statistical test. NGTDM extracted coarseness, busyness, complexity, strength and RLM extracted long run emphasis and run percentage are found to be significant by statistical test. Extracted features are computationally less expensive and attained an average accuracy of 80%, sensitivity of 94% and specificity of 71.4% using back propagation neural network classifier.

Statistical analysis using Bland-Altman agreement for technical methods of measuring blood glucose

Diabetes Mellitus is a disease which is spread worldwide, which can induce other systemic diseases with high mortality. The WHO gives estimation that there are more than 260 million people with diabetes, and the number shall double by 2030. Diabetes mellitus may be detected with few of the symptoms like thirst, blurring of vision, polyuria and weight loss. When it exceeds to be very severe it may even lead to coma and death. The determination of the level of the glucose in the blood is a necessary procedure in diabetes therapy, where the commonly used therapy involves the procedure of finger-prick measurements which is uncomfortable and causes skin injury. A noninvasive type painless therapy would improve the quality of life of patients by increasing compliance to monitoring blood glucose levels and thus hyper- and hypoglycemic episodes. The noninvasive glucose information interfaces with the other compounds due to which the precision of the device drops down and commercial less effective. The blood glucose monitoring techniques are briefly explained with their advantages and the limitations. A sample data set was obtained and the correlation and the Bland-Altman Plot agreement to interchange the measurement technique from invasive to noninvasive are discussed with the relevant graphs.

Reliable actuators for twin rotor MIMO system

Twin Rotor MIMO System (TRMS) is a bench mark system to test flight control algorithms. One of the perturbations on TRMS which is likely to affect the control system is actuator failure. Therefore, there is a need for a reliable control system, which includes H infinity controller along with redundant actuators. Reliable control refers to the design of a control system to tolerate failures of a certain set of actuators or sensors while retaining desired control system properties. Output of reliable controller has to be transferred to the redundant actuator effectively to make the TRMS reliable even under actual actuator failure.