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In tungsten inert gas (TIG) welding, limited depth of penetration can be achieved during single pass welding. To achieve the desired depth of penetration, the speed of welding needs to be significantly reduced and hence, the productivity decreases. In the present work, the effect of TiO2 activated flux on penetration is evaluated for different workpieces namely AISI 1020, AISI 304, AISI 316, and Duplex 2205 steels at different currents and shielding gas compositions. The results show a significant increase in the depth of penetration and reduction in the width-to-penetration ratio using the activated flux for all the workpiece materials considered here. Current increases the depth of penetration, however, the influence of flux becomes more significant with higher welding current. Maximum of 37.8%, 44.3%, 47%, and 124% increase in depths of penetration is measured for AISI 1020, AISI 304, AISI 316, and Duplex 2205 steels, respectively, when activated flux is used. Also, maximum of 70% increase in the depth...

In the present work, the influence of heat input is studied on depth of penetration while depositing bead on AISI 304 stainless steel using an indigenously fabricated automatic gas metal arc welding (GMAW) movement setup. Depth of penetration and fusion zone profiles are predicted at different conditions by the bond graph modeling approach and validated using measured depth of penetration and fusion profile. The effects of heat input on toughness and metallurgical behavior are analyzed while joining AISI 304 plates using automatic GMAW. Heat input and gas flow rate significantly influence the toughness at room temperature and at −20°C. Metallurgical observations by scanning electron microscopy are carried out and it is observed that high heat input and lower cooling rate increase grain size. High heat input and rapid cooling prevent grain growth and lead to grain refinement.

Gas metal arc welding (GMAW) offers highly efficient and low-cost welding, but manual movement of torch affects the uniformity of bead geometry, penetration, and heat input. In the present work, an indigenous automatic movement setup is designed and fabricated for GMAW. System behaviors like drive motor response, carriage, and wheel movement are studied through bond graph modeling. Welding time and welding velocity obtained from simulation are used to obtain the deposition efficiency during weld bead deposition on low carbon steel and stainless steel workpieces. Spatter index is also calculated for both the materials. Welding performance of automatic welding is compared with manual movement welding, and automatic welding is found capable to offer high deposition efficiency, low spatter index, uniform depth of penetration, and lower distortion for both the materials. Variation in microhardness and metallurgical observations by scanning electron microscopy are carried out for microstructure analysis.

The road accidents due to traffic problems and human erroneous driving are the major challenges for researches. The self-driving car or mobile robot is the solution to avoid such mishaps. In this paper, an attempted has been made to develop obstacle avoidance algorithms for bicycle vehicle model of mobile robots. The hybrid obstacle avoidance algorithm is proposed on the merits of line, wall following and tangent bug algorithm. The trajectory generated from the hybrid obstacle avoidance algorithm is fed into the overwhelming controller of the bicycle vehicle model of mobile robot for avoiding obstacles. Then, the fuzzy logic (FL) based obstacle avoidance controller is proposed. Twenty-three set of rules are proposed for fuzzy logic approach. Both the obstacle avoidance algorithms are implemented on the bicycle vehicle model of the mobile robot. The dynamic model of the mobile robot is developed using bond graph theory and is converted into Simulink block using S-function directly from the library of SYMBOLS Shakti software. The vehicle model is equipped with three ultrasonic sensors to measure the distance from the obstacles. Three input membership functions and one output membership function are considered in fuzzy logic controller. During avoiding two static obstacles and reaching the target, the comparison of obstacle free paths traced by both obstacle avoidance algorithms is done in this paper.

Neglecting dynamic load during design of a prismatic joint for high-speed operation may lead to unpredictable failures. A slider joint is usually a part of a pneumatic or hydraulic actuation device which may further involve complicated control systems. Thus, design/analysis of prismatic joints calls for a multi-energy domain modeling approach such as bond graph for reusability of the model in different application scenarios. The slider is treated to be a multibody system composed of two separate rigid bodies which are constrained to produce the desired motion. The constraints generate the dynamic contact forces which are used to compute the dynamic frictional forces. The bond graph model of the planar slider component developed in this article accurately calculates the dynamic loads. The model is first validated through numerical simulations performed on a Rapson slide. Thereafter, a multi-energy model for a V-twin engine and its mounting is developed to show how bond graph modeling makes it possible to create an integrated model of thermal, pneumatic and mechanical systems. Finally, the bond graph model of a three-dimensional prismatic joint is developed.

Combined regenerative and antilock braking in electric/hybrid-electric vehicles provides higher safety in addition to an energy storing capability. Development of a control law for this type of braking system is a challenging task. The antilock braking system (ABS) uses a control strategy to maintain the wheel slip within a predefined range. A sliding mode controller (SMC) for ABS is developed to maintain the optimal slip value. The braking of the vehicle, performed by using both regenerative and antilock braking, is based on an algorithm that decides how to distribute the braking force between the regenerative braking and the antilock braking in emergency/panic braking situations as well as in normal city driving conditions. Detailed bond graph models of a quarter car and four-wheeled vehicles are used in this article to implement and test the control laws. It is found that with combined regenerative and antilock braking, the vehicle’s safety increases (in terms of stopping distance and manoeuvrability) and some amount of kinetic energy can be recovered and stored in the regenerative battery pack. The passenger comfort is improved when a sliding mode ABS controller is used in place of a standard ABS controller for the mechanical braking part. Moreover, the influence of load transfer on the wheels during braking was evaluated on a four-wheeled vehicle model.

An overwhelming controller-based implicit system inversion scheme is proposed in this work to control a hydraulically driven planar (three-degrees-of-freedom) parallel manipulator. The physical model-based design of the controller is developed by using bond graphs. The electro-hydraulic actuator in the leg is modelled by including the dynamics of the servo-valve and the cylinder. A leg-space force-feedback controller is proposed for controlling the hydraulic pressures acting on the pistons of the actuators. The objective is to develop a fast inverse model which is suitable for real-time implementation in the controller. It is shown that an approximate inverse model which correctly represents the kinematics of motion but has incorrect representation of inertias is sufficient for the controller design because of the high feedback gains used in the overwhelming control strategy. This controller, based on the approximate simple inverse model, generates the right driving forces for the actual system whose model is much more complicated and uncertain. Finally, the controller design for a planar vehicle simulator is considered as an example and the corresponding simulation results are used to validate the robustness of the model-based overwhelming controller to the modelling uncertainties.

The present work concerns prediction of the amount of heat accumulation within the interior of a framed glass cabin and proposes some remedial measures to reduce temperature in the cabin. Various configurations such as double layer glass box filled with static air, static argon gas and flowing argon gas within the space between the two glass-layers are considered to conduct the experiments. Multi-physics bond graph models for these configurations are developed considering thermo-fluidic aspects. The experimental results are compared with the simulations using bond graph models. Though, direct application to a vehicle is not made, without loss of generality, the modelling and experimental procedure can be extended to analyze the heat accumulation inside a vehicle cabin when the vehicle is parked under direct sunlight.

This article deals with modeling of an intelligent autonomous vehicle with four traction wheels, four braking wheels and four-wheel steering system. The bond graph model of the integrated vehicle dynamic system is developed in a modular and hierarchical modeling environment. The Ackerman steering concept was used in the steering motor controller. Simulation results show the advantages of four-wheel steering during tight maneuvers.

Overwhelming controllers have been successfully used in the past for trajectory and impedance control. An overwhelming controller uses an image or copy of the system model in the model-based controller. This model represents the kinematic constraints for implicit system inversion. The controller output is used to actuate the controlled system through a high feedback gain, which ensures that the dynamics of the controller overwhelms the plant dynamics. The overwhelming controller implementation for a serial robotic system is a straightforward task. However, implementation of a bond graph model-based overwhelming controller for a parallel manipulator shows up a few difficult causal loops. Removal of these causal loops and a few other subtle modifications yield a computationally efficient inverse model for real-time implementation. As validation of the developed approach, trajectory tracking in constrained planar welding operation is considered. The corresponding simulation results are presented.