TITLE soldier can carry approximately 30% of

 

TITLE                     AN
AGGREGATED TRI-ORTHOSIS DESIGN FOR LOAD    

                                                  CARRYING
   EXOSKELETON

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ABSTRACT:

                      AGILITY is the eminent style of our
soldiers, who are the self imposed combination of Strength, Speed,
Re-activeness and Endurance. A soldier can carry approximately 30% of his body
weight and still retain a significant percentage of his maneuverability. But, a
load exceeding 45% of a soldier’s body weight, then he loses his robustness
significantly and is at greater risk for Injury. 

                          To aid such
impediments, we propose a biomimetic trio design that could be worn in close
proximity 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 while
strolling, it decreases the heaviness of the batteries that he should convey
and the outline can spare some vitality of the wearer. When walking downhill, the
resistance and power generation of device increases automatically, inturn reducing
the load on the wearer’s legs.

                          Based on a muscle
strength assessment study, we have designed a rigid load-bearing framework to
transfer weight off the wearer to the ground. A compact design of Pyroelectric
Infrared 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 torso
which generates electricity based on dorsi-flexor and plantar-flexor movements
and an artificial intelligence that adjusts the machinery to move with the
wearer is proposed. With the orthosis gait kinematics, man and machine can be
combined into an intimate, symbiotic unit that will perform essentially as one
wedded system. And our design provides a synergistic strategy for a
light-weight and efficient interpretation for the reality of a load carrying
exoskeleton for our soldiers.

 

 

 

 

 

 

 

Questionnaire

a)     
What
is your motivation behind participation?

Indian military, the fourth largest military in the world, is also the keeper
of the some of the most advanced and hi-tech weapons on the planet. India has
developed weapon technologies that are at par and even superior to that of the
US and Russia. We have the fastest cruise missile, more aircraft carriers, a
dedicated volunteer force and much more . Quality military hardware, original
military hardware and the best men any country could possibly have. But
we are still in the entry-level in exoskeleton domain. So we took this
challenge of proposing a wearable exoskeleton for our soldiers to assist them
in achieving their endeavors with supportive technologies. Being the building
blocks of our nation, We owe so much to the Indian Army who are the reason we
sleep peacefully at night, a perfect example of bravery.

 

b)    
What
are your specialized knowledge and expertise?

We
have attended the following seminars and workshops to gain knowledge on
robotics

·        
Robotic
Arm with artificial intelligence Workshop at Skyfi Labs Center, Guindy, Gate
Forum, Chennai

·        
One day
Workshop on ADVANCES in ROBOTICS and AUTOMATION, VIT University Chennai Campus,
ROBOTICS Workshop

·        
Robotics seminar at SRM Valliammai 

 

c)     
 Previous participation/awards/recognition if
any

Our
team bagged The Runner-up prize for paper presentation for our innovation of a
technology called POWER-UP which facilitates in charge sharing between mobile
devices in The NOKIA’s INNOVATION TECHNOLGICAL DAY, 2017.

 

d)    
 What are you planning to exhibit?

Our
team intend to exhibit our proposal in a combination of the below categories:

·        
Concept/technologies depicted through
2D/3D models, simulations/animations/software

·
    Concept paper presentations

 

 

 

 

 

 

 

TECHNICAL PROPOSAL:      

                      AN AGGREGATED TRI-ORTHOSIS DESIGN
FOR LOAD    

                                                  CARRYING
   EXOSKELETON

 

  
INTRODUCTION

                   Technology has been advanced
from swords to bows and arrows through the discovery of riffles and the
invention of the aircraft and now to the presence of unmanned laser guided
aerial drones and various robots. The military is now hoping for the new class
of warrior –Exoskeleton envisions dreams to come into reality and procreates dismounted
soldiers into a faster robust and empowered exoskeleton suits such as “iron
man”. 

                   Exoskeletons are external
skeleton structures that are used to protect animal’s body.  Military
Exoskeletons or exo-suits have been in development since early 1960’s, often
known as wearable robotics for military designed to boost soldier’s strength
and endurance. These are devices which are put on a human and are intended for
humans’ augmentation in particular to increase the efforts that a person may apply.

                   Exoskeletons help soldiers
to carry heavy loads both in and out of combat, run at faster speeds and defend
themselves from enemy attacks. These systems are anthromorphic (ascribing human
characteristics to nonhuman things)   devices that work in conjunction with our body’s
natural architecture. There are several factors driving the demand for these
exoskeletons globally. The most basic exoskeleton is more or less a pair of legs
taking the weight of an equipment rack.

EXISTING SYSTEMS:

·        
Raytheon’s XOS exoskeleton

·        
Lockheed Martin’s human universal load carrier (HULC) ,etc.,

have demonstrated
greatly improved strength, allowing soldier to carry loads of up to 200lbs for
extended periods of time. But they are hydraulic-powered, anthropomorphic
exoskeleton designed specifically to fit around the body of a dismounted
soldier. There is
no control mechanism, instead sensors detect movement and, using a
micro-computer, make the suit to move in time with the body.

 

PROBLEM STATEMENT

                   Robotic exoskeletons are
used for various purposes in different sizes. Exoskeletons can be classified
into full body, upper extremity (torso and hands) and lower extremity (for
legs) exoskeletons. One big problem was that these initial exoskeletons forced
wearers to walk in an unfamiliar way. This difficulty was compounded by a lack
of coordination between human and machine. A wearable exoskeleton solution is
to be conceived to aid the soldier and enhance his capabilities.

SOLUTION         

                 

                    We propose a further invention involved in
eliminating the main reason of former failures through the uses of different
approaches. Latest exoskeletons has been developed to reduce the weight that
impact on the wearer and also various exo-frames were introduced in both military
and medical fields for rehabilitation purposes such as restoring lost limb
functions.

Our
Exoskeleton is specifically designed for soldiers and acts as coalescence of technologies.

We
have proposed an exoskeleton which helps to carry load without causing an
effect for wearer. Former powered exoskeletons uses some mechanical movement as
a single power source and batteries or fuel cells as power storage which acted
as a main reason for weight of the exoskeleton.

Our
exo 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.

These
sources produce power enough to allow the exoskeleton produce the wearer
strength and endurance to move along with a load of approximated weight. Light
weight actuators have been used to create more compact design with better
characteristics.

HYPOTHESIS:                             

                       

                 The main reason behind
exoskeleton development is the augmentation of the physical abilities of a
human 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
many current robotic devices, producing better rehabilitation outcomes with robotic
devices is still a developing area of research.

 

To
design better robotic devices, it is important to understand:

·        
the principles governing how humans
learn to interact with the robotic assistance and

·        
How to identify the gait parameters
humans prioritize as objectives for their gait pattern. 

 

Considering
the above, the kinematic relationship has been understood to be robust both in
forward and backward locomotion and its nature is not altered by perturbing
gait patterns and changing gait speed.

 

 

 

 

In
order to apply human biomechanical data to design guidance for an exoskeleton,
six assumptions were made:

1.The
size, mass, and inertial properties 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 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 humans
carry loads on

their
backs.

6.
The exoskeleton will move at the same speed, cover the same distance, and carry
the same load as a soldier who does not have an exoskeleton.

 

DESCRIPTION:

                      Previous exoskeleton
development has largely been part of major research 

Endeavors and has
yielded solutions exhibiting high inertia limbs which are burdensome to
the wearer. Now let us have a study on the principal behind our
proposal.

 

POWER GENERATION FROM BACKPACK MOVEMENT:

 

                            When we walk, we
naturally optimize coordination patterns for energy efficiency. In order to
achieve maximum optimization, we have designed a fully portable hip-assistance
exosuit that uses a backpack frame to attach to the torso, onto which is
mounted a spooled-webbing actuator that connects to the back of the users
thigh. The actuators, powered by a geared brushless motor connected to a spool
via a timing belt, wind up seat-belt webbing onto the spool so that a large
travel is possible with a simple, compact mechanism.

                        The linkages were attached to the back frame
and were located on either side of the body. They acted as a first class lever
with the pivot at the center.The load and the actuating force were on either
ends of the link. The lengths of the links and the forces acting on them can be
calculated.The law of moments was applied to obtain the force that the actuator
must provide in order to lift the weight.

                         The back frame consists of two
vertical structures with two cross links in order to set them apart. L links
projecting backwards were used to attach the actuator.They were welded to the
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 be
determined.

Below
are the diagrametic depiction on the working and overview of our design.

The
material used was cold rolled steel. The axial stress, maximum normal stress
were calculated for each link and they were within the yield strength of the
material chosen. As shown in the figure a load is attached to a load plate
which is placed on the L links. Due to the walking movement of the wearer, a
force is applied on the linear actuators placed on the hip section which makes
the spring attached to the back frame move which instead provides vertical
movement to the load plate. This in turn generate power which is stored in the
battery situated beneath the L linkages. The power stored in the battery used
by the exoskeleton for the mechanical movements.

 

POWER GENERATED FROM KNEE

                         Scientists have proved
that every movement we do with our legs generate some amount of force which in
turn can be used to charge some devices. Power can be generated from these ankle
movements. This power generated can be collected and stored in a battery.Every time that you take a step, your
leg both accelerates and decelerates. For a walking movement, due to swinging
action a braking action happens at the knee joint. And it is this braking
mechanism generates energy, a generator that was able to absorb that
wasted energy and turn it into electricity is designed.

We have analyzed two types of robotic
exoskeletons movements to examine rapid locomotors adaptation to mechanical
assistance.

·        
Power absorption at heel strike
and 

·        
Power generation at toe-off.

In other
words, the
tibialis anterior has two main bursts of activity during gait:

·        
One at heel strike to slowly lower
the foot to the ground and

·        
One at toe-off to help provide toe clearance
during swing.

The former provides mechanical
power absorption at the ankle joint and the latter provides
mechanical power generation at the ankle joint.

                      The proposed controller captures the user’s intent to
generate task-related assistive torques by means of the exoskeleton in
different phases of the subject’s normal activity. Three dominant antagonistic
muscle pairs are used in our model, in which electromyography (EMG) signals (technique
for evaluating and recording the electrical activity produced by skeletal
muscles)are acquired, processed and used for the estimation of the

·        
knee
joint torque,

·        
trajectory
and

·        
the
stiffness trend,

 in real time. In addition, experiments can be
conducted of standing-up and sitting-down tasks are demonstrated to further
investigate the capabilities of the controller. Knee exoskeleton, can
effectively generate assistive actions that are volitionally and intuitively
controlled by the user’s muscle activity.

 

POWER GENERATION THROUGH SHOE

                              Energy harvesting is approaching an interesting
technological juncture wherein the power requirements for electronic devices
have been reduced while at the same time the efficiency of energy harvesting
devices has increased. Piezoelectric materials generate electricity when pressure is
applied to it. A piezoelectric generator in the sole of a shoe could produce
electricity with every step .This regenerative footstep is based on the
principle of piezoelectric effect in which pressure or strain applied to the
piezoelectric material placed in the insole of the wearers shoe  is
converted into electricity. The generated power can be used to power the
exoskeleton. Generation of electrical polarization of the material of the shoe
in response to the mechanical strain is practiced here. The efficiency and the power density of a piezoelectric
vibration energy harvester are strongly frequency dependent, because, the
piezoelectric material generates its maximum power at the electromechanical
resonance frequency.

 

HARVESTER DESIGN

                     The main structure of the
harvester is a sandwich structure, where a multilayer PVDF film is sandwiched
between two wavy surfaces of a movable upper plate and a lower plate, as shown
in Figure When the upper plate is subject to a compressive force produced by
foot, the upper plate moves down and the PVDF film is stretched along 1-axis
simultaneously.

                    This leads to a
piezoelectric field created inside every PVDF layer, driving the free electrons
in 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 force
is lifted, the upper plate moves up and the PVDF film is relaxed, therefore the
piezo-potential diminishes, resulting in releasing the accumulated electrons.
The sandwich structure is characterized by the inner wavy surfaces, where
arc-shaped grooves and arc-shaped ribs exist. The specially designed surfaces
enable the PVDF film to generate a large longitudinal deformation and reduce
the harvester thickness, which enhances the harvesting performance and makes it
possible 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.

DEPICTION
OF OUR TRIO DESIGN

Walking
With Loads

                         In 2000, Harman, Hoon,
Frykman, and Pandorf reported about the effects of load carriage onlower
extremity biomechanics during walking. Joint angle data were collected and
joint momentswere calculated for carried backpack loads of 6, 20, 33, and 47 kg
while subjects walked at aspeed of approximately 1.33 m/s. In contrast tochange
in walking speed, the instant when toe-off occurs in the gait cycle was
affected by changein 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 transitionsfrom flexion to
extension and extension to flexion also appears to be affected by change incarried
load.

                        The effect of change in
carried load on hip joint angles was not reported, but slightchanges in knee
and 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 an
increase in carried load.

                          At the ankle, peak
dorsiflexionduring terminal stance (? 30% to 50% gait cycle) was found to
decrease from approximately11.5 to 10 degrees, and peak plantarflexion at the
transition from mid- to terminal swing (? 90%gait cycle) was found to
decrease from approximately 5 to 3.5 degrees with an increase in carriedload.
As with the joint angles, timing of transitions from extensor to flexor and
flexor to extensormoments, as well as peak values obtained at each joint,
appears to be affected by change incarried load.

                        At the hip, peak
extensor moment values during loading response, as well as peakflexor moment
values during terminal stance, were found to increase with an increase in
carried load. Peak knee extensor moment values during mid-stance and peak ankle
plantarflexor moment values during terminal stance were also found to increase
with an increase in carried load, while peak knee flexor and ankle dorsiflexor
moments did not follow a monotonically increasing trend.

The peak extensor and flexor moment
values obtained at each joint under each of the four

different backpack loads are summarized
in Table .

 

MINE
DETECTION

                   As an advancement of sole
power generator we have attached a additional feature for our exoskeleton. The
insole of this made up of a conductive material and has a planar coil printed
in 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 metal
detectors consist of inductor coil which is used to interact with the mine
inside the ground. This insole produces electromagnetic frequency waves and
detects the mine within 6.5ft (2m). When the electromagnetic field is disrupted as there is a mine in the ground it the radio
transmitter transmits signal to the wristwatch and produces an alarm signal
to the watch cinched on the wearer’s wrist and thus the location of the mine is
manifested 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 humans
through an exoskeleton is what researchers have been thriving for. Many
different exoskeletons for various body parts have been developed to try and
assist human movements efficiently. This research proposes the development of a
power generating exoskeleton to assist the human through ambulation while
carrying a substantial payload. Even though Exoskeletons are been into
existence for more than a 5 decades, they are still facing many challenges
related to power supply, weight, battery existence etc. These Limitations have
been tried to overcome in this proposal. We being the budding engineers , have come
up with a solution to solve some exiting problems faced by former exo skeletons
to assist our troops in war field.

REFERENCES

1.      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=1

4.      http://exoskeletonreport.com/2016/07/military-exoskeletons/

5.      https://science.howstuffworks.com/exoskeleton.htm

6.      http://www.arl.army.mil/arlreports/2002/ARL-TR-2764.pdf