INTRODUCTION Technology has been advanced from swords to bows and arrows through thediscovery of riffles and the invention of the aircraft and now to the presenceof unmanned laser guided aerial drones and various robots. The military is nowhoping for the new class of warrior –Exoskeleton envisions dreams to come intoreality and procreates a dismounted soldier into a faster robust and empoweredexoskeleton suits such as “iron man”. Exoskeletonsare external skeleton structures that are used to protect animal’s body. Military Exoskeletons or exo-suits have been in development since early1960’s, often known as wearable robotics for military designed to boostsoldier’s strength and endurance.
These are devices which are put on a humanand are intended for humans’ augmentation in particular to increase the effortsthat a person may apply. Exoskeletons help soldiers to carry heavy loads both in and out ofcombat, run at faster speeds and defend themselves from enemy attacks. Thesesystems are anthromorphic (ascribing human characteristics to nonhumanthings) devices that work inconjunction with our body’s natural architecture. There are several factorsdriving the demand for these exoskeletons globally. The most basic exoskeleton is more orless a pair of legs taking the weight of an equipment rack.EXISTING SYSTEMS:· Raytheon’s XOSexoskeleton · Lockheed Martin’shuman universal load carrier (HULC) ,etc.
,have demonstrated greatly improved strength, allowing soldier tocarry loads of up to 200lbs for extended periods of time. But they arehydraulic-powered, anthropomorphic exoskeleton designed specifically to fitaround the body of a dismounted soldier. There is no control mechanism, instead sensors detectmovement and, using a micro-computer, make the suit to move in time with thebody. PROBLEMSTATEMENT Robotic exoskeletons areused for various purposes in different sizes. Exoskeletons can be classifiedinto full body, upper extremity (torso and hands) and lower extremity (forlegs) exoskeletons. One big problem was that these initial exoskeletons forcedwearers to walk in an unfamiliar way. This difficulty was compounded by a lackof coordination between human and machine. A wearable exoskeleton solution isto be conceived to aid the soldier and enhance his capabilities.
SOLUTION We propose a furtherinvention involved in eliminating the main reason of former failures throughthe uses of different approaches. Latest exoskeletons has been developed toreduce the weight that impact on the wearer and also various exo-frames wereintroduced in both military and medical fields for rehabilitation purposes suchas restoring lost limb functions. Our Exoskeleton is specifically designed forsoldiers and acts as coalescence of technologies. We have proposed anexoskeleton which helps to carry load without causing an effect for wearer.Former powered exoskeletons uses some mechanical movement as a single powersource and batteries or fuel cells as power storage which acted as a mainreason for weight of the exoskeleton. Our exo suit consists of distributed power sourcesof three types:(1) Power generated from backpack movement.
(2) Powergenerated from the wearers knee and (3) Powergenerated from the wearers shoe. These sources produce power enough to allow theexoskeleton produce the wearer strength and endurance to move along with a loadof approximated weight. Light weight actuators have been used to create morecompact design with better characteristics. HYPOTHESIS: The main reason behindexoskeleton development is the augmentation of the physical abilities of ahuman being, specifically strength and endurance for the current state of the art.Human walking carries a lot of energy, although this has been realized by manycurrent robotic devices, producing better rehabilitation outcomes with roboticdevices is still a developing area of research. To design better robotic devices, it isimportant to understand:· theprinciples governing how humans learn to interact with the robotic assistanceand· Howto identify the gait parameters humans prioritize as objectives for their gaitpattern. Considering the above, the kinematicrelationship has been understood to be robust both in forward and backwardlocomotion and its nature is not altered by perturbing gait patterns andchanging gait speed.
In order to apply human biomechanicaldata to design guidance for an exoskeleton, six assumptions were made:1. The size, mass, and inertialproperties of the exoskeleton will be equivalent to those of a human.2. The exoskeleton will carry itself(including power supply) and the soldier’s load.3. The joint torques and joint powersscale linearly with mass.4. The exoskeleton’s gait will be thesame as a human’s gait.
5. The exoskeleton will carry a load onits back in the same way those humans carry loads on theirbacks.6. The exoskeleton will move at the samespeed, cover the same distance, and carry the same load as a soldier who doesnot have an exoskeleton. DESCRIPTION: Previousexoskeleton development has largely been part of major research Endeavors and has yielded solutions exhibiting high inertialimbs which are burdensome to the wearer. Now let us have a study on theprincipal behind our proposal. POWER GENERATION FROM BACKPACK MOVEMENT: Whenwe walk, we naturally optimize coordination patterns for energy efficiency. Inorder to achieve maximum optimization, we have designed a fully portablehip-assistance exosuit that uses a backpack frame to attach to the torso, ontowhich is mounted a spooled-webbing actuator that connects to the back of theusers thigh.
The actuators, powered by a geared brushless motor connected to aspool via a timing belt, wind up seat-belt webbing onto the spool so that alarge travel is possible with a simple, compact mechanism. The linkages wereattached to the back frame and were located on either side of the body. Theyacted as a first class lever with the pivot at the center.The load and theactuating force were on either ends of the link. The lengths of the links andthe forces acting on them can be calculated.The law of moments was applied toobtain the force that the actuator must provide in order to lift the weight.
The back frame consists oftwo vertical structures with two cross links in order to set them apart. Llinks projecting backwards were used to attach the actuator.They were welded tothe back frame.The actuators were fixed rigidly at the end to the back frame.Hence the stress induced in the L link and the strength of the welds must to bedetermined. The material used was coldrolled steel.
The axial stress, maximum normal stress was calculated for eachlink and they were within the yield strength of the material chosen. As shownin the figure a load is attached to a load plate which is placed on the Llinks. Due to the walking movement of the wearer, a force is applied on thelinear actuators placed on the hip section which makes the spring attached tothe back frame move which instead provides vertical movement to the load plate.
This in turn generates power which is stored in the battery situated beneaththe L linkages. The power stored in the battery used by the exoskeleton for themechanical movements. POWERGENERATED FROM KNEE Scientists have provedthat every movement we do with our legs generate some amount of force which inturn can be used to charge some devices. Power can be generated from these anklemovements. This power generated can be collected and stored in a battery.Every time that you take a step, yourleg both accelerates and decelerates. For a walking movement, due to swingingaction a braking action happens at the knee joint.
And it is this brakingmechanism generates energy, a generator that was able to absorb thatwasted energy and turn it into electricity is designed.We have analyzed twotypes of robotic exoskeletons movements to examine rapid locomotors adaptationto mechanical assistance.· Power absorption at heel strikeand · Power generation at toe-off.In other words, the tibialisanterior has two main bursts of activity during gait: · One at heel strike to slowly lowerthe foot to the ground and · One at toe-off to help providetoe clearance during swing.
Theformer provides mechanical power absorption at the ankle joint andthe latter provides mechanical power generation at the ankle joint. The proposed controller captures the user’s intent togenerate task-related assistive torques by means of the exoskeleton indifferent phases of the subject’s normal activity. Three dominant antagonisticmuscle pairs are used in our model, in which electromyography (EMG) signals (techniquefor evaluating and recording the electrical activity produced by skeletalmuscles)are acquired, processed and used for the estimation of the · kneejoint torque, · trajectoryand· thestiffness trend, in realtime. In addition, experiments can be conducted of standing-up and sitting-downtasks are demonstrated to further investigate the capabilities of thecontroller. Knee exoskeleton, can effectively generate assistive actions that arevolitionally and intuitively controlled by the user’s muscle activity. POWER GENERATION THROUGH SHOE Piezoelectricmaterials generate electricity when pressure is applied to it. A piezoelectricgenerator in the sole of a shoe could produce electricity with every step .
Thisregenerative footstep is based on the principle of piezoelectric effect inwhich pressure or strain applied to the piezoelectric material placed in theinsole of the wearers shoe is converted into electricity. The generatedpower can be used to power the exoskeleton. Generation of electricalpolarization of the material of the shoe in response to the mechanical strainis practiced here. Walking With LoadsIn 2000, Harman, Hoon, Frykman and Pandorf reportedabout the effects of load carriage on lower extremity biomechanics duringwalking. Joint angle data were collected and joint moments were calculated forcarried backpack loads of 6, 20, 33, and 47 kg while subjects walked at a speedof approximately 1.33 m/s. In contrast to change in walking speed, the instantwhen toe-off occurs in the gait cycle was affected by change in carried load.
As carried load increased from 6 to 47 kg, the duration of the stance phase wasobserved to increase from approximately 63.4% to 65.2% of the gait cycle.Timing of transitions from flexion to extension and extension to flexion alsoappears to be affected by change in carried load.
The effect of change incarried load on hip joint angles was not reported, but slight changes in kneeand ankle joint angles were. Peak knee flexion during mid-stance (? 10%to30% gait cycle) was found to increase from approximately 22.5 to 27.5degrees, while peak knee flexion at the transition from initial to mid-swing(? 72% gait cycle) was found to decrease from approximately 68 to 64degrees with an increase in carried load. At the ankle, peak dorsi flexion duringterminal stance (? 30% to 50% gait cycle) was found to decrease fromapproximately11.5 to 10 degrees, and peak plantar flexion at the transitionfrom mid- to terminal swing (? 90%gait cycle) was found to decrease fromapproximately 5 to 3.5 degrees with an increase in carried load.
As with thejoint angles, timing of transitions from extensor to flexor and flexor toextensor moments, as well as peak values obtained at each joint, appears to beaffected by change in carried load. At the hip, peak extensor moment valuesduring loading response, as well as peak flexor moment values during terminalstance, were found to increase with an increase in carried load. Peak kneeextensor moment values during mid-stance and peak ankle plantar flexor moment valuesduring terminal stance were also found to increase with an increase in carriedload, while peak knee flexor and ankle dorsi flexor moments did not follow amonotonically increasing trend.Thepeak extensor and flexor moment values obtained at each joint under each of thefourdifferentbackpack loads are summarized in Table .
MINE DETECTION As an advancement of solepower generator we have attached an additional feature for our exoskeleton. Theinsole of this made up of a conductive material and has a planar coil printedin the form of ultra thin layer. This insole consists of an ultra thinmicroprocessor. This mine detection works on the principle of metal detector.These metal detectors consist of inductor coil which is used to interact withthe mine inside the ground. This insole produces electromagnetic frequencywaves and detects the mine within 6.5ft (2m) radius.
When the electromagneticfield is disrupted as there is a mine in the ground it theradio transmitter transmits signal to the wristwatch and produces an alarmsignal to the watch cinched on the wearer’s wrist and thus the location of themine is manifested on the watch screenADVANTAGESExoskeleton is a technology developed not only toimprove soldier work but also to change lives. Exoskeletons were beyond humanability and will be lighter than current versions so that it can be worn forlonger periods of time. These exoskeletons were fully integrated so that you can sustain the most capabilityat the lowest impact to the soldier. Battery usage augments the exoskeletoneven at the idle state of the wearer though it stores less amount ofelectricity. This exo suit compensate well on combat even when one of the powersources gets damaged due to external factors. Our exo suit works mainly onfeedback principle were the output achieved during walking is given as theinput to the actuators and the exoskeleton.LIMITATIONSAll the systems generally have limitations, since thisis in the conceptual stage total power generation and the cost for creating theprototype will be estimated at the time of implementation only. At initial stage, the battery must be fully chargedbefore the wearer uses suit.
May be due to vertical oscillations the wearer getsuncomfortable with the backpack.Since these suits acts in parallel with the wearer’smuscles and tendons it could mimic their function CONCLUSION The ability to assist humans through an exoskeleton is what researchershave been thriving for. Many different exoskeletons for various body parts havebeen developed to try and assist human movements efficiently. This researchproposes the development of a power generating exoskeleton to assist the humanthrough ambulation while carrying a substantial payload.
Even thoughExoskeletons are been into existence for more than a 5 decades, they are stillfacing many challenges related to power supply, weight, battery existence etc.These Limitations have been tried to overcome in this proposal. We being the buddingengineers, have come up with a solution to solve some exiting problems faced byformer exo skeletons to assist our troops in war field.