Balakrishnan Shankar

Inverse kinematics of a dual linear actuator pitch/roll heliostat

This work presents a simple, computationally efficient inverse kinematics solution for a pitch/roll heliostat using two linear actuators. The heliostat design and kinematics have been developed, modeled and tested using computer simulation software. A physical heliostat prototype was fabricated to validate the theoretical computations and data. Pitch/roll heliostats have numerous advantages including reduced cost potential and reduced space requirements, with a primary disadvantage being the significantly more complicated kinematics, which are solved here. Novel methods are applied to simplify the inverse kinematics problem which could be applied to other similar problems.

Low cost and real time electronic speed controller of position sensorless brushless DC motor

Brushless DC (BDC) motors are widely used in aerospace applications because of their high power to weight ratio, low maintenance and reliable operation over long periods of time. These advantages also make them preferred over brushed DC motors for several other applications. But the requirement of an electronic speed controller for commutation and customization for specific applications makes BDC a costly affair. This paper presents a low cost and real time electronic speed controller for BDC motors. The motor is started using the motor phase saturation inductance change method. Further control of the motor is established by monitoring the back emf zero crossing as a feedback. In addition, MATLAB simulink based simulations have been performed to analyse the circuit performance under real time input conditions.

Development of X-ray Protective Garments from Rare Earth-modified Natural Rubber Composites

Commonly used shielding materials while X-ray imaging by clinical persons is based on lead but incessant contact with this toxic material can pave way to severe health problems. Polymer composites, embedded with lead-free additives, especially based on natural rubber can be chosen as a suitable alternative candidate due to its lightweight, cost-effectiveness and capability to absorb regular energy region of X-ray used in medical imaging. Rubber composites were prepared with modified rare earth oxides at different filler loadings. The characterization of the filler reveals that their size falls in the nanoregime, which, in turn, supplemented to the superior properties of the composites. Mechanical properties were found to increase with filler content. X-ray shielding studies were done at different tube voltages and thicknesses and the results prove the efficacy of materials to be considered as a promising shielding resource.

Remote triggered virtual laboratory for Hooke's law using LabVIEW

By the advent of the new millennia there have been notable changes in the way students get their education. Remote triggered labs standout among these education methodologies for their user interaction and active involvement. Remote Triggered Virtual Labs experiments enhance both theoretical and practical learning experience using real time data streaming and analysis. Real time data streaming includes plotting laboratory experiment data values to the user, showing trigger and control buttons and signals and live video streaming of the respective experiment. This paper describes the framework and methodology for the creation of a Remote Triggered Virtual Laboratory experiment for teaching Hookes Law, a key engineering principle in the Mechanics of Solids. It describes how the experiment works from a technical perspective, how the user interacts with and conducts the experiment, and the novel strategies and methodologies used.

Remote triggered flywheel energy storage with dynamic braking

This work describes the design and implementation of a novel mechanism for the study of a flywheel energy storage system with dynamic braking. Dynamic braking is suitable for short duration energy requirements and hence works well with they flywheel setup. The flywheel set up integrates DC motors with motor controller card and a data acquisition system to effectively monitor, acquire and record the real time values. The lab allowed students to remotely access the network and run the DC flywheel experiment. The user interface design allowed students to observe the traces of energy storage and depletion when acceleration and deceleration of flywheel occurred. The work successfully demonstrated how complex phenomena can be taught using Virtual Laboratory experimentation.

Virtual labs battery and ultracapacitor characterization

Virtual labs help students and professionals to learn subjects practically. Remote triggered virtual labs, in which real hardware is remotely controlled is especially well suited for students who do not have access to high quality, modern, and often expensive lab equipment. It also allows to students to conduct laboratory experiments on their own time and repeat them as often and when necessary. In this paper, we have implemented Energy Storage studies in (batteries and ultra(super)capacitors at the collegiate level through remote triggered virtual labs. The hardware and software system allows the user to study the charge and discharge characteristics of different types of batteries and ultracapacitors. This will create interest for students and professionals to study more on batteries and ultracapacitors and emerge with new ideas on energy storage. In this work, we compare two hardware setups, one made from scratch with low-cost components and the other created using professional, research grade components. The paper focuses on the design, implementation, control system, measurement, communication protocols and integration with the internet for these two testing setups using Labview.

Innovative Dynamic Stability Control for VTOLs using thrust vectoring

Single Rotor based Vertical Take Off and Landing systems are more prone to stability issues than normal aircraft. The main factors causing instability are anti torque, pitching and rolling. Anti torque, which causes the body of the aircraft to turn in the opposite direction to the rotor, is generated as the engine turns the rotor against the air. Pitching and rolling, on the other hand, can be caused due to sudden turbulent air conditions during the flight of the aircraft. Todays anti torque mechanisms, like the tail rotors of helicopters, cause the overall system to be bulky and complex. In this paper, a compact automated mechanism is presented which can be used to attain stability in VTOL vehicles. Experimental verification of the system is being performed on a modeled aircraft. Analysis using Velocity Triangles and CFD has been carried out on this system.

Magnetic and dielectric properties of nickel-ferrite-embedded natural rubber composites

Spinel-structured nickel ferrite has been prepared using co-precipitation method. The ferrite particles prepared were characterized using XRD, FTIR, and TEM and were confirmed to be in the nano-regime. Natural rubber composites were prepared with different loadings of nickel ferrite like 5, 15, 25, 50, and 75 (in part per hundred rubber, phr). The mechanical, swelling, and magnetic properties were analyzed using the standard methods. Dielectric measurements show that permittivity decreases with increase in frequency and increases with increase in ferrite loading. Tan delta value also was found to increase with filler loading which may be attributed to the presence of interfacial polarization.

Remote triggered monitoring of wind performance using Weibull and Rayleigh distributions

In this era of depleting fossil fuels and global warming, alternative sources of energy are critical to mankinds survival, making its study imperative for energy engineering students. This work demonstrates the design, development and implementation of a remote triggered experiment to analyze wind data and correlate it with Weibull and Rayleigh distributions performed in coastal Kerala, in southwest India. Interfacing instrumentation with the server and website, in order to collect the wind speed and direction, is enumerated. This work provides a platform that can remotely control, capture and model both short term and long term wind data thereby overcoming a critical barrier in bringing wind energy experimentation to engineering classrooms, namely lack of in-house wind power analysis systems. Additionally, the platform allows testing the feasibility of turbine installations based on predictions from the Rayleigh and Weibull probability distributions.

An Advanced Spider-Like Rocker-Bogie Suspension System for Mars Exploration Rovers

This paper describes the working of the system design for the Mars rover. The rover, developed to compete in the Mars Society’s University Rover Challenge 2015, was designed to perform various tasks such as site survey, sample return, equipment servicing, and astronaut assistance in a Mars-like landscape of dry, non-vegetated, rocky terrain. The complete design features a bioinspired eight-wheeled drive mechanism, an integrated robotic arm along with a stereo vision technique for advanced image processing. This paper focuses on the drive mechanism of the rover design. The 8-wheeled rover combines the rocker-bogie mechanism with four rocker wheels and four spider-leg wheels. The spider legs ensure that it can traverse over heights greater than the chassis height, which could be three times as much as the diameter of the wheels. NASA’s current rover can only traverse a height twice the diameter of the wheel. Additionally, the wheels are actuator-powered, and hence, the slope of the rover can be adjusted in such a way that it does not topple for a wide range of inclination allowing the rover to traverse over highly rugged terrain. The rover design can be modified for many applications notably the exploration of alien planets, deep sea trench, and other environments where human exploration is almost impossible. This effort to make the rover mechanism more efficient may one day be instrumental in detecting life and many such possibilities, in Mars and other planets.