Nirmal Baran Hui

Coordinated motion planning of multiple mobile robots using potential field method

The present paper deals with the navigation of multiple wheeled robots working in a common dynamic environment, in a decentralized manner. A potential field-based motion planner has been developed to plan the motion of the robots and a strategic approach has been proposed to develop the decision making support. Performance of the developed approaches have been tested through computer simulations. Proposed strategy has been found to solve the conflicts and induced coordination among the agents.

MOMENT ANALYSIS OF A SCROLL EXPANDER USED IN AN ORGANIC RANKINE CYCLE

Recent studies on small-scale power generation with the organic Rankine cycle suggest superior performance of positive displacement type of expanders compared to turbines. Scroll expanders in particular achieve high isentropic efficiencies due to lower leakage and frictional losses. Performance of scroll machines may be enhanced by the use of non-circular involute curves in place of the circular involutes resulting non-uniform wall thickness. In this paper, a detailed moment analysis is performed for such an expander having volumetric expansion ratio of 5 using thermodynamic models proposed earlier by one of the present authors. The working fluid considered in the power cycle is R-245fa with scroll inlet temperature of 125 degrees C for a gross power output of similar to 3.5 kW. The model developed in this paper is verified with an air scroll compressor available in the literature and then applied to an expander Prediction of small variation of moment with scroll motion recommends use of scroll expander without a flywheel over other positive displacement type of expanders, e.g. reciprocating, where a flywheel is an essential component.

Fuzzy PID Control for Ball and Beam Mechanism

A ball beam mechanism is found to be highly unstable system. PID control has been mostly used for stabilizing the same. However, tuning of PID controller gains is a difficult issue. In this work, attempt has been made to develop a fuzzy model-based ball and beam mechanism. Initially, an analytical model of the system is presented in the nonlinear state space form. The feasibility of the proposed scheme for ball and beam system is demonstrated using MATLAB/SIMULINK. Computer simulations are exploited to demonstrate the validity and feasibility of the developed control schemes.

Forward and reverse modelling of flow forming of solution annealed H30 aluminium tubes

Modelling of flow forming of tube-shaped solution annealed H30 Aluminium alloy is considered in the present study. Initially, a total of 136 experiments have been conducted to realize the process and subsequently influences of three inputs (feed–speed ratio, roller infeed and axial stagger) on the three outputs, viz. internal diameter, springback and ovality have been studied. Three neural network-based approaches (back-propagation neural network, limited-memory BFGS network and genetic neural system) have been developed for forward as well as reverse modelling of the process. During forward modelling, the performances of the three neural network-based approaches have been compared with the regression model. It is seen that GANN has performed much better compared to the other methods. Percentage accuracy in predicting ovality using regression analysis is the worst, and it necessitates consideration of more input process parameters for better prediction accuracy. However, NN-based approaches adapted such cases well. Comparison of all the three NN-based approaches among themselves has been made during reverse modelling. During this process, prediction accuracy, using LBFGSNN, is found to be better than the other two methods. Thus, it is perceived that NN-based models might suit better for prediction of shape accuracy of flow-formed shell.

Control of Two-Axis Helicopter Model Using Fuzzy Logic

Twin Rotor MIMO System becomes unstable quite easily and control becomes extremely difficult. Present paper is in search of a standard controller to be used for stabilizing such a complex system. Comparison between ZN-tuned PID and fuzzy logic controller has been made in this study. Initially, mathematical model of the system has been developed and simulated in MATLAB. At the end, the developed controllers are tested through a prototype Twin Rotor Multiple Input Multiple Output System (TRMS).

Development of ANFIS Model for Flow Forming of Solution Annealed H30 Aluminium Tubes

Modeling of the cold flow forming process for manufacturing of tube shaped solution annealed H30 Aluminum alloy has been considered in this present study. Three inputs (feed-speed ratio, roller in-feed and roller axial stagger) and three outputs viz. spring back, ovality and internal diameter have been considered for the present study.. Adaptive network-based fuzzy inference system (ANFIS) in Matlab platform has used for modeling purposes and its performance is compared with regression model. ANFIS has completely outperformed the regression models. Percentage accuracy in predicting all the three responses are found to be very high with ANFIS models. Prediction of ovality against the test data using regression analysis is found to be extremely erroneous. It indicates that additional process parameters are involved in predicting ovality which are not captured during the experimentation.

Genetic neural-based modeling of AC resistance of heating coil used for high-frequency inverter-fed induction cooker

The present paper deals with modeling of AC resistance of twisted litz wires used for high-frequency inverter-fed induction cooker. Several traditional approaches are available, most of which have concentrated in deriving the analytical relationships between the AC resistances with the parameters of the wire. However, it is very difficult to get the exact relationship, due to several reasons. An attempt is made in this paper to model the AC resistance using a three-layered feed-forward Neural Network. For this purpose, four inputs (wire type, number of strand, number of spiral turn and operating frequency) and one output as AC resistance have been considered. Since the performance of Neural Network alone might not be optimal; it is optimized using a binary-coded Genetic Algorithm. Performances of the proposed approach were compared with the method of AC resistance computation proposed by Ferreira. Genetic-neural system has given a very close accuracy, and the computational complexity was found to be very low. Thus, it is suitable for online implementations.

Design and Development of Intelligent Autonomous Robots

The present chapter deals with the issues related to design and development of autonomous mobile robots. One of the major issues in developing an intelligent and autonomous robot is to design an appropriate scheme for planning its motion without any human intervention. Both conventional potential field method as well as soft computing-based approaches have been developed for the said purpose. Initially, the performances of all the approaches have been studied through computer simulations. Thereafter, real experiments are conducted to test the effectiveness of the said approaches. A camera-based vision system has been used to collect information of the environment, while carrying out the real experiments.