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Tuesday, 28 February 2012


The flight control system is a key element that allows the missile to meet its system performance requirements. The objective of the flight control system is to force the missile to achieve the steering commands developed by the guidance system. The types of steering commands vary depending on the phase of flight and the type of interceptor. In the boost phase the flight control system may be designed to force the missile to track a desired flight-path angle or attitude. In the mid-course and terminal phases the system may be designed to track acceleration commands to effect an intercept of the target. 


Tuesday, 21 February 2012



Here is a simple verilog code for ALU. It uses case statements to decide the operation to be done on operands.

     code    -> opcode for alu to do specific operation
     a,b,cin -> input operands
     out,c_out -> output

NOTE: code, a, b, out are 4 bit operands

     . . . . .

Friday, 17 February 2012

ISRO Scientist 2012 - ICRB - applicaion - guide


Department of Space, Government of India


Annual Recruitment of Scientists/Engineers 'SC' with BE/B.TECH  OR Equivalent Degree in
Electronics, Mechanical



Indian Space Research Organisation [ISRO] is engaged in application of Space Science and Space Technology for the development of society at large and for serving the nation by achieving self-reliance by indigenously developing capability to design and develop Space Transportation Systems and Satellites.

Wednesday, 15 February 2012



                Artificial Intelligence is a branch of Science which deals with helping machines finds solutions to complex problems in a more human-like fashion. This generally involves borrowing characteristics from human intelligence, and applying them as algorithms in a computer friendly way. A more or less flexible or efficient approach can be taken depending on the requirements established, which influences how artificial the intelligent behavior appears.
Humans throughout history have always sought to mimic the appearance, mobility, functionality, intelligent operation, and thinking process of biological creatures. This field of biologically inspired technology, having the moniker biometrics, has evolved from making static copies of human and animals in the form of statues to the emergence of robots that operate with realistic appearance and behavior. This paper covers the current state-of-the-art and challenges to making biomimetic robots using artificial muscles.

             AI is generally associated with Computer Science, but it has many important links with other fields such as Math’s, Psychology, Cognition, Biology and Philosophy, among many others. The ability to combine knowledge from all these fields will ultimately benefit the progress in the quest of creating an intelligent artificial being. Advances in medicine have led to the
availability of artificial blood, replacement joints, heart valves, and heart-lung machines that are common implanted. device. Muscle is a critically needed organ and its availability in an artificial form for medical use can greatly contribute to the improvement of the quality of life of many humans. Thus these electroactive polymers (EAP) that are also known as artificial muscles can potentially address this need. These materials are human made actuators that have the closest operation similarity to biological muscles.

Motivation of Artificial Intelligence:
       Computers are fundamentally well suited to performing mechanical computations, using fixed programmed rules. This allows artificial machines to perform simple monotonous tasks efficiently and reliably, which humans are ill-suited to. For more complex problems, things get more difficult... Unlike humans, computers have trouble understanding specific situations, and adapting to new situations. Artificial Intelligence aims to improve machine behavior in tackling such complex tasks.

                  There are many different approaches to Artificial Intelligence, some are obviously more suited than others in some cases, but any working alternative can be defended. Over the years, trends have emerged based on the state of mind of influential researchers, funding opportunities as well as available computer hardware.
Artificial life through robotics:
Laws of Robotics:
1. A robot may not injure a human being or, through inaction, allow a human being to come to harm.
2. A robot must obey the orders given it by human beings except where such orders would conflict with the first law.
3. A robot must protect its own existence as long as such protection does not conflict with the first or second law.
                          Robotics has been an evolution of the field of automation where there was a desire to emulate biologically inspired characteristics of manipulation and mobility. In recent years, significant advances have been made in robotics, artificial intelligence and others fields allowing to make sophisticate biologically inspired robots [Bar-Cohen and Brea zeal. Biologically inspired robotics is a subset of the interdisciplinary field of biomimetics. Technology progress resulted in machines that can recognize facial expressions, understand speech, and perform mobility very similar to living creatures including walking, hopping, and swimming. Further, advances in polymer sciences led to the emergence of artificial muscles using Electro active Polymer (EAP) materials that show functional characteristics remarkably similar to biological muscles.   Making creatures that behave like the biological model is a standard procedure for the animatronics industry that is quite well graphically animates the appearance and behavior of such creatures. However, engineering such biomimetic intelligent creatures as realistic robots is still challenge due to the need to physical and technological constraints.

Artificial muscles:
                  Muscles are the key to the mobility and manipulation capability of biological creatures and when creating biomimetic it is essential to create actuators that emulate muscles. The potential to make such actuators is increasingly becoming feasible with the emergence of the electro active polymers (EAP), which are also known as artificial muscles [Bar-Cohen, 2001]. These materials have functional similarities to biological muscles, including resilience, damage tolerance, and large actuation strains. Moreover, these materials can be used to make mechanical devices with no traditional components like gears, and bearings, which are responsible to their high costs, weight and premature failures. The large displacement that can be obtained with EAP using low mass, low power and, in some of these materials also low voltage, makes them attractive actuators. The capability of EAPs to emulate muscles offers robotic capabilities that have been in the realm of science fiction when relying on existing actuators.

FIGURE 1: A graphic illustration of the grand challenge for the development of EAP actuated robotics – an arm wrestling match against human.
             Unfortunately, the EAP materials that have been developed so far are still exhibiting low conversion efficiency, are not robust, and there are no standard commercial materials available for consideration in practical applications. In order to be able to take these materials from the development phase to application as effective actuators, there is a need for an established infrastructure. For this purpose, it is necessary to develop comprehensive understanding of EAP materials' behavior, as well as effective processing, shaping and characterization techniques. The technology of artificial muscles is still in its emerging stages but the increased resources, the growing number of investigators conducting research related to EAP, and the improved collaboration among developers, users, and sponsors are leading to a rapid progress.
            Robots, which could build other robots, tried to protect humans from everything until people could not do anything by themselves. Biggest supporters of AI research is military. One of the reasons is that in "...a nuclear age, a new generation of very intelligent computers incorporating AI could actually defend the country better, faster, and more rationally than humans.

Biometric robots using EAP:
                   Mimicking nature would significantly expand the functionality of robots allowing   performance of tasks that are currently impossible. As technology evolves, great number of biologically inspired robots actuated by EAP materials emulating biological creatures is expected to emerge. The challenges to making such robots can be seen graphically in Figure 2 where humanlike and dog-like robots are shown to hop and express joy. Both tasks are easy for humans and dogs to do but are extremely complex to perform by existing robots.

FIGURE 2: Making a joyfully hopping human-like and dog-like robots actuated by EAP materials are great challenges for biomimetic robots

FIGURE 3: An android head and a robotic hand that are serving as biomimetic platforms for the development of artificial muscles.

Categories of EAP:
                         EAP can be divided into two major categories based on their activation mechanism including ionic and electronic. The electronic EAP are driven by Coulomb forces and they include: Dielectric EAP (shown in Fig.4a), Electrostrictive Graft Elastomers, Electrostrictive Paper, Electro-Viscoelastic Elastomers, Ferroelectric Polymers and Liquid Crystal Elastomers (LCE). This type of EAP materials can be made to hold the induced displacement while activated under a DC voltage, allowing them to be considered forrobotic applications. These materials have a greater mechanical energy density and they can be operated in
air with no major constraints. However, the electronic EAP require a high activation fields (>30-V/μm) that may be close to the breakdown level. In contrast to the electronic EAP, ionic EAP are materials that involve
mobility or diffusion of ions and they consist of two electrodes and an electrolyte. The activation of the ionic EAP can be made by as low as 1-2 Volts and mostly a bending displacement is induced. The ionic
EAP include Carbon Nanotubes (CNT), Conductive Polymers (CP), Electro Rheological Fluids (ERF), Ionic Polymer Gels (IPG), and Ionic Polymer Metallic Composite (IPMC) (shown in Fig.4b). Their disadvantages are the need to maintain wetness and they pose difficulties to sustain constant displacement under activation of a DC voltage (except for conductive polymers).
a. Dielectric EAP in relaxed (top) and
activated states (bottom)
b. IPMC in relaxed (left) and activated states (right)
Examples of EAP materials in relaxed and activated states.
         The induced displacement of both the electronic and ionic EAP materials can be designed geometrically to bend, stretch or contract. Any of the existing EAP materials can be made to bend with a significant bending response, offering an actuator with an easy to see reaction.

FIGURE4a. Dielectric EAP in relaxed (top) and activated states (bottom).

FIGURE4b. IPMC in relaxed (left) and activated states (right)