Manivannan P. V.

During a cornering manoeuvre, in a vehicle equipped with Ackerman steering geometry, the inner tire operates at a higher slip angle relative to the outer tire. As lateral load transfer occurs, the potential of the inner tires to produce the lateral force reduces and with systems like active steering, the saturation of lateral force occurs even earlier. In order to have an ideal steering geometry, at low speeds the system should follow Ackerman geometry closely and at higher speeds it should follow anti-Ackerman geometry. The tire workload (TW) distribution is a critical variable to be analyzed to prevent tire force saturation. The present paper aims to formulate the wheel angle relation for front wheel steering based on tire workload distribution. The tire workload difference (TWD) between the steered wheels is chosen as the active variable to arrive at the wheel angle relation. To study the transient behavior of the vehicle with tire workload redistribution (TWR), the Mimuro plot is used. The developed wheel angle relation utilizes the tire forces effectively and the results show improved cornering performance of the vehicle. This type of study which accounts for balancing tire workload for both lower and higher cornering speeds based on wheel angle relation has not been reported earlier in literature.

The Prototype Fast Breeder Reactor (PFBR) has eight Steam Generators (SG), each with 547 tubes connecting top and bottom headers. The integrity of these tubes is ascertained using periodic In-Service Inspection (ISI) procedures. Two-Axis Tube Locator Module (TLM) is a robotic manipulator designed to be used to precisely locate all 547 tubes. The difference in the device work plane and the tube sheet plane is mainly due to error from tolerances in fabrication and error due to mounting the device. These errors hinder the accurate positioning of inspection device over the tubes for inspection. In this work, a novel approach to calibrate the TLM is attempted by using motor encoder as sensors, to calibrate the TLM without using any external calibration devices. In this work, a three-point calibration is used to compute transformation matrix using two-axis motor encoder as sensors, for measuring the displaced position of calibration point tubes and using SVD on the correlation matrix formed from the original and transformed points. Even though three independent measurements (x, y, z axis) are required to spatially ascertain the positioning error of the probe with respect to calibration point tube, it proved that planar 2D measurement using readily available servo motor encoder sensors itself is adequate for the calibration of TLM without much loss of accuracies. The degenerated sensing reduces the cost, effort, and time for calibrating the TLM for use in inspection.

This paper presents the development of a system for analyzing and adapting the Human Arm motion for virtual reality applications. The proposed system consists of number of Flex sensors, Inertial Measurement Units and Embedded Data Acquisition System, to record the joint angles for deriving the kinematic states (position, velocity and acceleration) of different parts of the human arm. A flexible structure is used for holding the sensors on the human arm at the required position, without hindering the movement. The embedded circuit utilizes a 32-bit Microcontroller to process the data from various sensors and transmits digitized data to the central computer for computing the various kinematics parameters. The system has been tested against standard motion tracking device and is found to perform close to the reference device with an average error of 6%. Such a device can be used to simulate critical operations in medicine and industry and analyze performance during various tasks. © (2014) Trans Tech Publications, Switzerland.

The objective of this research work is to model a dynamical system that can undergo flexible deformations along with the general rigid-body motions. For the system to be able to provide precise outputs when excited by an input, the modal shapes need to be examined and a suitable control strategy is required to make the manipulator to adapt to a particular use. The input shaping parameters have been analyzed for specific modes of vibrations. The model uses a Gaussian input torque and Power Spectral Density (PSD) plots are developed with suitable sampling frequency. The plots show the variation of PSD for the modes of vibration under consideration, thereby providing an insight into the shaping parameters of the Gaussian input. © (2014) Trans Tech Publications, Switzerland.

This paper presents a hybrid lateral and longitudinal controller for a self-driving passenger car. The controller comprises a Proportional Derivative (PD) controller as a closed loop controller and Neural Network (NN) based adaptive compensator as a feed forward controller. The activation function of the NN adaptive stage is based on a poly-harmonic Thin Plate Spline (TPS) Radial Basis Function (RBF), which promises better accuracy, smoother interpolation and closed form solutions. The controller development and testing has been performed using a non-linear vehicle dynamics model, which has been developed using the Matlab/Simulink tool. The Controller performance in terms of vehicle lane following (lateral deviation control) and safe cruising control (longitudinal spacing error control) have been verified through simulations. Reductions of lateral deviation error by 15% and longitudinal spacing error by 7% have been achieved. © (2014) Trans Tech Publications, Switzerland.

Prototype Fast Breeder Reactor (PFBR) has eight Steam Generators (SG) that transfers the heat from molten sodium to the water and converts the water into super-heated steam. SG is a shell and tube type counter flow heat exchanger, which has 547 steam tubes connecting the top and bottom headers of the SG. These steam tubes are surrounded by Sodium and water/steam will be flowing in the tubes. (i.e. sodium is present in the shell side and water/steam in the tube side). The water/steam pressure will be 172 bar and any breach in one of the tubes (due to crack) will eventually result in water coming in contact with sodium and leading to violent reaction. Hence, all mitigation efforts are to be taken proactively to isolate a degrading tube(s) through proper Pre-Service inspection (PSI) and In-Service inspections (ISI) using Remote Field Eddy Current technique (RFEC). Though PSI is a comprehensive inspection, ISI is generally carried out on 10% of the total heat transfer area, i.e. about 54 tubes, through periodic inspections. A two-axis robotic system called PFBR SG Inspection System (PSGIS) is used to position the probe/cable pusher end effector system to perform the tube inspection with RFEC probe. Since there is no straight forward scheme available to optimally choose the inspection sequence, Genetic Algorithm (GA) is used to optimize the tube inspection order to reduce the duty cycle and total inspection time. In this work, we have developed a genetically evolved optimal inspection algorithm to reduce overall inspection time and the results of the investigations are presented.

Unstructured road detection is one of the difficult tasks for self-driving cars than the detection of road with proper lane markings. Also, it is an extremely difficult task to detect the highly deteriorated district and taluk roads using currently available vision-based algorithm; as the exposed gravels and grass covering on both sides (edges) of road adds more noise in the input image. To address this issue, a novel vision-based road detection technique is proposed in this research work. This new method uses noise to enhance the road edges in the image and unstructured straight road is detected using Hough Transform. This paper is divided into three parts: bird’s eye view transformation of 2D road image received from the vehicle camera to correct the perspective distortion and easier identification of Region of Interest (ROI), addition of noise in the ROI of image to differentiate the valid road from the background and use of Hough Transform to identify the edges of unstructured road having no road markings. Finally, we present a simple way to find the centerline on the detected road for departure warning to reduce the additional computation. The simulation results corroborate that the proposed method detects the road successfully and can be used in real-time detection system.

Trajectory planning of robot’s center of gravity (CoG) is the main concern when a legged robot is walking. The trajectory of the robot should be framed such that the center of pressure (CoP) of the robot should lie within supporting polygon at all time. This paper deals with the study of support polygon and graphical analysis to find the location of CoG, where the robot has high chances to go to instability. The quadrilateral supporting phases are utilized to avoid these instability locations. Further, the analysis is done to find the timely sequence of lift and touchdown of legs (lift and touch are called as events of legs). Based on the sequence of events and the support polygon analysis, trajectory of the robot is defined, which can produce smooth, steady, and stable robot motion. Though the robot gains static stability by trajectory planning, its dynamic stability should also be verified. This is done using zero moment point (ZMP) method. The analysis done in this paper is for the unswaying robot, walking on flat terrain.

The Steam Generators used in the Prototype Fast Breeder Reactor have sodium on shell side and water/steam on the tube side. Tube inspection and qualification of all 547 tubes, enhances the safety and reduces the operation cost by increasing plant availability. In this work, a two-axis planar reach robotic arm called as Tube Locator Module (TLM) is used for reaching and orienting the Remote Field Eddy Current (RFEC) testing probe at the exact location of individual Steam Generator tube, and the probe is pushed through the entire tube length for inspection and qualification of the same. A conventional method of inverting the Jacobian and using a pseudo inverse will help in running the actuators in joint space to reach the desired position of the end effector. However, as pseudo inverse suffers numerical stability close to singularities of the manipulator, hence it is proposed to use the damped least squares pseudo inverse method by introducing a damping factor to improve the stability. Higher damping factor increases the stability of manipulator, even when the manipulator moves closer to its singular configurations. However, higher damping factors lead to more tracking error in the end-effector trajectory. Hence, in this work, based on the tracking errors and the geometrical constraints, an optimal damping factor is arrived at for the smooth motion of the TLM. This paper also deals with the manipulability study of the TLM to understand the singular configurations, and apply the damping factor to stabilize the joint angular velocities without causing much error in the end-effector trajectory.

We mathematically analyze the correlations that arise between measurement parameters. This is done by understanding the geometrical transformations that a data point undergoes when correlations are determined between normally distributed measurement parameters. We use this understanding to develop a new algorithm for the discrete Kalman Filter. The analysis and methodology adopted in this work can be extended to the derivatives of Kalman Filter, resulting in similar improvements. The effectiveness of this method is verified through simulations of mobile robot mapping problem with an Extended Kalman Filter and the results are presented.