TITLE soldier can carry approximately 30% of
TITLE ANAGGREGATED TRI-ORTHOSIS DESIGN FOR LOAD CARRYING EXOSKELETON ABSTRACT: AGILITY is the eminent style of oursoldiers, who are the self imposed combination of Strength, Speed,Re-activeness and Endurance. A soldier can carry approximately 30% of his bodyweight and still retain a significant percentage of his maneuverability.
But, aload exceeding 45% of a soldier’s body weight, then he loses his robustnesssignificantly and is at greater risk for Injury. To aid suchimpediments, we propose a biomimetic trio design that could be worn in closeproximity to the body that can generate power by itself rather consuming it,which is achieved with the support of ENERGY SCAVENGING. In the event that a fighter can produce additional power whilestrolling, it decreases the heaviness of the batteries that he should conveyand the outline can spare some vitality of the wearer.
When walking downhill, theresistance and power generation of device increases automatically, inturn reducingthe load on the wearer’s legs. Based on a musclestrength assessment study, we have designed a rigid load-bearing framework totransfer weight off the wearer to the ground. A compact design of PyroelectricInfrared Sensors and actuators at the knee, ankle and hip to increase strength;soft materials that buffer between the human being and the rigid frame;hip-assistance structure that uses a backpack frame to attach to the torsowhich generates electricity based on dorsi-flexor and plantar-flexor movementsand an artificial intelligence that adjusts the machinery to move with thewearer is proposed. With the orthosis gait kinematics, man and machine can becombined into an intimate, symbiotic unit that will perform essentially as onewedded system. And our design provides a synergistic strategy for alight-weight and efficient interpretation for the reality of a load carryingexoskeleton for our soldiers. Questionnairea) Whatis your motivation behind participation?Indian military, the fourth largest military in the world, is also the keeperof the some of the most advanced and hi-tech weapons on the planet. India hasdeveloped weapon technologies that are at par and even superior to that of theUS and Russia. We have the fastest cruise missile, more aircraft carriers, adedicated volunteer force and much more .
Quality military hardware, originalmilitary hardware and the best men any country could possibly have. Butwe are still in the entry-level in exoskeleton domain. So we took thischallenge of proposing a wearable exoskeleton for our soldiers to assist themin achieving their endeavors with supportive technologies. Being the buildingblocks of our nation, We owe so much to the Indian Army who are the reason wesleep peacefully at night, a perfect example of bravery. b) Whatare your specialized knowledge and expertise?Wehave attended the following seminars and workshops to gain knowledge onrobotics· RoboticArm with artificial intelligence Workshop at Skyfi Labs Center, Guindy, GateForum, Chennai· One dayWorkshop on ADVANCES in ROBOTICS and AUTOMATION, VIT University Chennai Campus,ROBOTICS Workshop· Robotics seminar at SRM Valliammai c) Previous participation/awards/recognition ifanyOurteam bagged The Runner-up prize for paper presentation for our innovation of atechnology called POWER-UP which facilitates in charge sharing between mobiledevices in The NOKIA’s INNOVATION TECHNOLGICAL DAY, 2017. d) What are you planning to exhibit?Ourteam intend to exhibit our proposal in a combination of the below categories:· Concept/technologies depicted through2D/3D models, simulations/animations/software· Concept paper presentations TECHNICAL PROPOSAL: AN AGGREGATED TRI-ORTHOSIS DESIGNFOR LOAD CARRYING EXOSKELETON INTRODUCTION Technology has been advancedfrom swords to bows and arrows through the discovery of riffles and theinvention of the aircraft and now to the presence of unmanned laser guidedaerial drones and various robots.
The military is now hoping for the new classof warrior –Exoskeleton envisions dreams to come into reality and procreates dismountedsoldiers into a faster robust and empowered exoskeleton suits such as “ironman”. Exoskeletons are externalskeleton structures that are used to protect animal’s body. MilitaryExoskeletons or exo-suits have been in development since early 1960’s, oftenknown as wearable robotics for military designed to boost soldier’s strengthand endurance. These are devices which are put on a human and are intended forhumans’ augmentation in particular to increase the efforts that a person may apply. Exoskeletons help soldiersto carry heavy loads both in and out of combat, run at faster speeds and defendthemselves from enemy attacks. These systems are anthromorphic (ascribing humancharacteristics to nonhuman things) devices that work in conjunction with our body’snatural architecture.
There are several factors driving the demand for theseexoskeletons globally. The most basic exoskeleton is more or less a pair of legstaking the weight of an equipment rack.EXISTING SYSTEMS:· Raytheon’s XOS exoskeleton · Lockheed Martin’s human universal load carrier (HULC) ,etc.,have demonstratedgreatly improved strength, allowing soldier to carry loads of up to 200lbs forextended periods of time. But they are hydraulic-powered, anthropomorphicexoskeleton designed specifically to fit around the body of a dismountedsoldier. There isno control mechanism, instead sensors detect movement and, using amicro-computer, make the suit to move in time with the body.
PROBLEM STATEMENT 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 further invention involved ineliminating the main reason of former failures through the uses of differentapproaches. Latest exoskeletons has been developed to reduce the weight thatimpact on the wearer and also various exo-frames were introduced in both militaryand medical fields for rehabilitation purposes such as restoring lost limbfunctions. OurExoskeleton is specifically designed for soldiers and acts as coalescence of technologies.
Wehave proposed an exoskeleton which helps to carry load without causing aneffect for wearer. Former powered exoskeletons uses some mechanical movement asa single power source and batteries or fuel cells as power storage which actedas a main reason for weight of the exoskeleton. Ourexo suit consists of distributed power sources of three types:(1)Power generated from backpack movement. (2) Power generated from the wearers knee and (3) Power generated from the wearers shoe. Thesesources produce power enough to allow the exoskeleton produce the wearerstrength and endurance to move along with a load of approximated weight.
Lightweight actuators have been used to create more compact design with bettercharacteristics.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 theart. Human walking carries a lot of energy, although this has been realized bymany current robotic devices, producing better rehabilitation outcomes with roboticdevices is still a developing area of research.
Todesign better robotic devices, it is important to understand:· the principles governing how humanslearn to interact with the robotic assistance and· How to identify the gait parametershumans prioritize as objectives for their gait pattern. Consideringthe above, the kinematic relationship has been understood to be robust both inforward and backward locomotion and its nature is not altered by perturbinggait patterns and changing gait speed. Inorder to apply human biomechanical data to design guidance for an exoskeleton,six assumptions were made:1.Thesize, mass, and inertial properties of the exoskeleton will be equivalent tothoseof a human.2.The exoskeleton will carry itself (including power supply) and the soldier’sload.
3.The joint torques and joint powers scale linearly with mass.4.The exoskeleton’s gait will be the same as a human’s gait. 5.The exoskeleton will carry a load on its back in the same way those humanscarry loads on theirbacks.6.
The exoskeleton will move at the same speed, cover the same distance, and carrythe same load as a soldier who does not have an exoskeleton. DESCRIPTION: Previous exoskeletondevelopment has largely been part of major research Endeavors and hasyielded solutions exhibiting high inertia limbs which are burdensome tothe wearer. Now let us have a study on the principal behind ourproposal. POWER GENERATION FROM BACKPACK MOVEMENT: When we walk, wenaturally optimize coordination patterns for energy efficiency. In order toachieve maximum optimization, we have designed a fully portable hip-assistanceexosuit that uses a backpack frame to attach to the torso, onto which ismounted a spooled-webbing actuator that connects to the back of the usersthigh. The actuators, powered by a geared brushless motor connected to a spoolvia a timing belt, wind up seat-belt webbing onto the spool so that a largetravel is possible with a simple, compact mechanism. The linkages were attached to the back frameand were located on either side of the body. They acted as a first class leverwith the pivot at the center.
The load and the actuating force were on eitherends of the link. The lengths of the links and the forces acting on them can becalculated.The law of moments was applied to obtain the force that the actuatormust provide in order to lift the weight. The back frame consists of twovertical structures with two cross links in order to set them apart.
L linksprojecting backwards were used to attach the actuator.They were welded to theback frame.The actuators were fixed rigidly at the end to the back frame. Hencethe stress induced in the L link and the strength of the welds must to bedetermined. Beloware the diagrametic depiction on the working and overview of our design.
Thematerial used was cold rolled steel. The axial stress, maximum normal stresswere calculated for each link and they were within the yield strength of thematerial chosen. As shown in the figure a load is attached to a load platewhich is placed on the L links. Due to the walking movement of the wearer, aforce is applied on the linear actuators placed on the hip section which makesthe spring attached to the back frame move which instead provides verticalmovement to the load plate.
This in turn generate power which is stored in thebattery situated beneath the L linkages. The power stored in the battery usedby the exoskeleton for the mechanical movements. POWER GENERATED 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 two types of roboticexoskeletons movements to examine rapid locomotors adaptation to mechanicalassistance.· Power absorption at heel strikeand · Power generation at toe-off.In otherwords, thetibialis anterior 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 provide toe clearanceduring swing. The former provides mechanicalpower absorption at the ankle joint and the latter providesmechanical 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 real time. In addition, experiments can beconducted of standing-up and sitting-down tasks are demonstrated to furtherinvestigate the capabilities of the controller. Knee exoskeleton, caneffectively generate assistive actions that are volitionally and intuitivelycontrolled by the user’s muscle activity. POWER GENERATION THROUGH SHOE Energy harvesting is approaching an interestingtechnological juncture wherein the power requirements for electronic deviceshave been reduced while at the same time the efficiency of energy harvestingdevices has increased. Piezoelectric materials generate electricity when pressure isapplied to it.
A piezoelectric generator in the sole of a shoe could produceelectricity with every step .This regenerative footstep is based on theprinciple of piezoelectric effect in which pressure or strain applied to thepiezoelectric material placed in the insole of the wearers shoe isconverted into electricity. The generated power can be used to power theexoskeleton. Generation of electrical polarization of the material of the shoein response to the mechanical strain is practiced here. The efficiency and the power density of a piezoelectricvibration energy harvester are strongly frequency dependent, because, thepiezoelectric material generates its maximum power at the electromechanicalresonance frequency. HARVESTER DESIGN The main structure of theharvester is a sandwich structure, where a multilayer PVDF film is sandwichedbetween two wavy surfaces of a movable upper plate and a lower plate, as shownin Figure When the upper plate is subject to a compressive force produced byfoot, the upper plate moves down and the PVDF film is stretched along 1-axissimultaneously.
This leads to apiezoelectric field created inside every PVDF layer, driving the free electronsin the external circuit to accumulate on the upper and lower 3-axis surfaces(electrodes) of every PVDF layer to screen the piezo-potential. When the forceis lifted, the upper plate moves up and the PVDF film is relaxed, therefore thepiezo-potential diminishes, resulting in releasing the accumulated electrons.The sandwich structure is characterized by the inner wavy surfaces, wherearc-shaped grooves and arc-shaped ribs exist. The specially designed surfacesenable the PVDF film to generate a large longitudinal deformation and reducethe harvester thickness, which enhances the harvesting performance and makes itpossible to integrate the harvester into a shoe whose inner space is limited.DESIGN:(a)The sandwich structure of the harvester; (b)The multilayer PVDF film; (c)The force applied by foot drive the upper plate to move up and down circularly;(d)The design parameters.DEPICTIONOF OUR TRIO DESIGNWalkingWith Loads In 2000, Harman, Hoon,Frykman, and Pandorf reported about the effects of load carriage onlowerextremity biomechanics during walking. Joint angle data were collected andjoint momentswere calculated for carried backpack loads of 6, 20, 33, and 47 kgwhile subjects walked at aspeed of approximately 1.
33 m/s. In contrast tochangein walking speed, the instant when toe-off occurs in the gait cycle wasaffected by changein carried load. As carried load increased from 6 to 47 kg,the duration of the stance phase wasobserved to increase from approximately63.
4% to 65.2% of the gait cycle. Timing of transitionsfrom flexion toextension and extension to flexion also appears to be affected by change incarriedload. The effect of change incarried load on hip joint angles was not reported, but slightchanges 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 27.5 degrees,while peak kneeflexion at the transition from initial to mid-swing (? 72%gait cycle) was found to decrease fromapproximately 68 to 64 degrees with anincrease in carried load. At the ankle, peakdorsiflexionduring terminal stance (? 30% to 50% gait cycle) was found todecrease from approximately11.5 to 10 degrees, and peak plantarflexion at thetransition from mid- to terminal swing (? 90%gait cycle) was found todecrease from approximately 5 to 3.5 degrees with an increase in carriedload.As with the joint angles, timing of transitions from extensor to flexor andflexor to extensormoments, as well as peak values obtained at each joint,appears to be affected by change incarried load. At the hip, peakextensor moment values during loading response, as well as peakflexor momentvalues during terminal stance, were found to increase with an increase incarried load. Peak knee extensor moment values during mid-stance and peak ankleplantarflexor moment values during terminal stance were also found to increasewith an increase in carried load, while peak knee flexor and ankle dorsiflexormoments did not follow a monotonically increasing trend.
The peak extensor and flexor momentvalues obtained at each joint under each of the fourdifferent backpack loads are summarizedin Table . MINEDETECTION As an advancement of solepower generator we have attached a 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 thin microprocessor.
This mine detection works on the principle of metal detector. These metaldetectors consist of inductor coil which is used to interact with the mineinside the ground. This insole produces electromagnetic frequency waves anddetects the mine within 6.5ft (2m). When the electromagnetic field is disrupted as there is a mine in the ground it the radiotransmitter transmits signal to the wristwatch and produces an alarm signalto the watch cinched on the wearer’s wrist and thus the location of the mine ismanifested on the watch screen ADVANTAGES Exoskeletons were beyond human ability and will be lighter than current versions so that it can be worn for longer periods of time. Our exoskeleton design is fully integrated so that you can sustain the most capability at the lowest impact to the soldier. Battery usage augments the exoskeleton even at the idle state of the wearer though it stores less amount of electricity. Our exo-design works mainly on feedback principle were the output achieved during walking is given as the input to the actuators and the exoskeleton.
The major advantage of our design is that, it has a trio orthosis design, as if one module fails to generate power, the other two modules will be supportive. LIMITATIONS All the systems generally have limitations, since this is in the conceptual stage total power generation and the cost for creating the prototype will be estimated at the time of implementation only. At initial stage, the battery must be fully charged before the wearer uses suit. May be due to vertical oscillations the wearer gets uncomfortable with the backpack, but that doesn’t comensate to its efficiency. Since these suits acts parallel with the wearer’s muscles and tendons it could mimic their function. CONCLUSION The ability to assist humansthrough an exoskeleton is what researchers have been thriving for.
Manydifferent exoskeletons for various body parts have been developed to try andassist human movements efficiently. This research proposes the development of apower generating exoskeleton to assist the human through ambulation whilecarrying a substantial payload. Even though Exoskeletons are been intoexistence for more than a 5 decades, they are still facing many challengesrelated to power supply, weight, battery existence etc. These Limitations havebeen tried to overcome in this proposal. We being the budding engineers , have comeup with a solution to solve some exiting problems faced by former exo skeletonsto assist our troops in war field.
REFERENCES1. http://ieeexplore.ieee.org/document/5509167/2. https://news.
wisc.edu/power-walk-footsteps-could-charge-mobile-electronics/3. https://deepblue.lib.umich.
edu/bitstream/handle/2027.42/63763/kaop_1.pdf?sequence=14. http://exoskeletonreport.
com/2016/07/military-exoskeletons/5. https://science.howstuffworks.com/exoskeleton.
htm6. http://www.arl.army.mil/arlreports/2002/ARL-TR-2764.pdf
