Advanced Materials Research Vols. 403-408

Abstract: A simplified method for the calculation of Common-mode (CM) electromagnetic interference (EMI) caused by Three-phase PWM rectifier is presented. EMI analysis in time domain presents particular problems due to complex geometry and the wide range of time constants involved. This makes the simulation of EMI a complex matter. The method presented here is based on a “Matrix representation” process and is specially designed to simplify the mentioned problems. In this paper, quick and robust simulations were preferred rather than very accurate results. Once the disturbances sources are calculated parameters of the propagation path can be changed giving a new prediction immediately. To evaluate the performances of this analytical approach the frequency-domain model is compared with Saber simulations.

Abstract: In this paper, optimization of fabrication process for microneedles has been presented. Using inductively coupled plasma (ICP) etching technology, fabrication of out-of-plane hollow silicon microneedles for blood extraction has been carried out. Sharp tip microneedles with length 1100 µm were designed for fabrication. The fabrication of microneedles was not successful because the lumen section was fabricated first and then hole was created for fluid flow. Previously, using same fabrication method successful fabrication of microneedles was done for drug delivery with length 200 µm. This fabrication method is not suitable for long structure. Thus, the alternative microneedle fabrication steps using ICP etching have been developed and presented in this paper. These steps can be more optimized and suitable for sharp tip, long and hollow structure.

Abstract: A simulation model for the analysis of MEMS capacitor has been developed using mechanical equivalencies. The capacitor structure used in this paper has four parallel plates to improve the tuning range. Two of the plates are suspended and the other two plates are fixed. The developed mechanical model is validated with the help of structure simulations performed using PolyMumps process. The simulation results show good correlation between the equivalent mechanical model and the structural model. The tuning range of the mechanical model developed is 2.465:1 where as the PolyMumps fabricated capacitor produces a tuning range of 2.4555:1.The mechanical resonant frequencies of the top and bottom suspended plates are simulated as 501 rad/sec and 706 rad/sec respectively.

Abstract: In this paper, we present the design verification of PolyMUMPs based monolithic tri-axis MEMS capacitive accelerometer. The physical level simulation has been done using the analyzer module of Coventorware to verify the performance of the three-axis accelerometer using Finite Element Method (FEM) and compared with the optimized results obtained in ANSYS and in MATLAB. The 2D model is created in the designer module of Coventorware. The 3D layout is generated in the preprocessor module and mesh is created on solid model. Proposed three axis accelerometer has three individual single axis accelerometers, integrated on a single substrate uniformly centered on single axis. Low mechanical noise, high sensitivity and sense capacitance have been measured for all axes individually and presented. The results obtained from both the analytical and finite element models are found to be in excellent agreement.

Abstract: This paper presents a hybrid obstacle avoidance methodology for autonomous navigation of a mobile robot in an unstructured environment. Decision is taken based on the classical method depending on the environmental scenario where the space between multiple obstacles is measured and the feasibility of passing the robot through any immediate pair of obstacles examined. In other cases, the decision is taken by the Fuzzy Logic controller. The developed algorithm is simulated and experimentally validated with a mobile robot platform equipped with forward-looking sonar for obstacle detection. Odometry sensors assist in localization of the mobile robot. The developed algorithm is found adequately intelligent to navigate the robot from any start position through to the desired goal position avoiding obstacles, and without taking recourse to any pre-built map. The simulated results exhibit fair agreement with the experimental results.

Abstract: This paper attempts to design a Luenberger-like nonlinear observer and a nonlinear state-feedback controller for trajectory tracking of a single-input/single-output nonlinear system exhibiting chaotic dynamics. Using a nonlinear transformation, the nonlinear system is first transformed into a linear system and thereafter a control law is designed for trajectory tracking. The controller, designed on the basis of an input-output linearized model, is applied on both the linearized as well as the nonlinear system. The results are validated through simulation on a Duffing oscillator.

Abstract: Input-Output data modeling using multi layer perceptron networks (MLP) for a laboratory helicopter is presented in this paper. The behavior of the two degree-of-freedom platform exemplifies a high order unstable, nonlinear system with significant cross-coupling between pitch and yaw directional motions. This paper develops a practical algorithm for identifying nonlinear autoregressive model with exogenous inputs (NARX) and nonlinear output error model (NOE) through closed loop identification. In order to collect input-output identifier pairs, a cascade state feedback (CSF) controller is introduced to stabilize the helicopter and after that the procedure of system identification is proposed. The estimated models can be utilized for nonlinear flight simulation and control and fault detection studies.

Abstract: In this paper, our aim was to the control the Rotary crane by using Fuzzy logic. For this one must obtain the mathematical model of the crane. After obtaining the model, the dynamics of the crane is identified. The Rotary crane is to be controlled in such a manner to increase the system speed without compromising the stability and safety of the whole system. Also the load is transferred to desired location accurately. The main advantage of Fuzzy based control is that no parameter identification is required as compare to other control strategies available. There are some applications where the conventional control strategies cannot provide the desired response up to certain level. But the fuzzy logic based control is capable of enhance the response, since it has learning capability which helps to create the accurate rules for each separate conditions. Also this fuzzy based control will reduce oscillations of payload to prevent hazards for people and equipments in the work place, industries.

Abstract: This paper presents a robust Feedback Linearization (FL) based pitch plane autopilot design for a highly maneuvering, skid-to-turn, tail controlled tactical missile. Owing to the highly nonlinear missile dynamics, firstly a feedback linearization based controller is proposed. As the resulting design lacks robustness, the issue is addressed by robustifyng the FL based controller using Extended State Observer (ESO). The system uncertainties are estimated by the ESO and the estimate is used in the FL control to nullify it’s effect. A novel feature of this technique is that it does not require any knowledge of the system uncertainty. Simulation results are presented to demonstrate the effectiveness of the proposed approach.

Abstract: Inverted Pendulum is a standard problem in control systems and is appropriate for depicting linear control principles. In this system there is an inverted pendulum connected to a cart that moves along a horizontal track with the help of a motor. We can determine the cart’s position and velocity from the motor and the rail track limits the cart’s movement in a bidirectional path. The pendulum’s angle of deviation and the position of the cart are determined by two sensors mounted on the system. Essential measurements and motor control signals are generated by a medium control board linking the computer and the system. Analysis of the results and yielding the control commands are done with the help of a MATLAB program. This is indeed a single input- dual output system because we must be able to control two parameters (pendulum’s angle and cart’s position) with just one control signal to the motor. Since the PID (Proportional Integral Derivative) controller is usually proper for SISO (Single Input Single Output) systems, we are eager to propose a procedure to control one of these parameters underneath the other. In this paper two tactics are described: 1. controlling the cart’s position beneath the pendulum’s angle, and 2. controlling the pendulum’s angle beneath the cart’s position. Regarding the results, one method is proven to be superior. We also mention some practical considerations in this paper.