Abstract
: – As the powers of modern Engineering grow by the day, Exoskeletons are fast
becoming an exciting field of research & innovation. The capabilities are
immense, and we plan to implement a few of them. Our aim is to build an
Exoskeleton, that can help our soldiers in lifting heavy objects,  help in movement in adverse condition, act as
a bulletproof vest under firing breakouts. The exoskeleton can also behave as a
gas mask in case the soldier is in some area affected by some poisonous gas. We
also plan to use ElectroCardioGraphy  to
analyse the mental state of the concerned soldier, and alert in case he is
found to be drowsy or inattentive. The exoskeleton has a self-powering system,
which gives it autonomous power, eliminating the requirements of any external
power source. Also, it will be light weight & easy to remove, in case it is
not needed or stops working due to adverse conditions.   The idea is to make a bilateral exoskeleton having
six degrees of freedom. Using closed loop control systems, the performance of
the exoskeleton can also be checked & corrected in case it is not optimal
& efficient. At the areas where human body has joints for movement, we are
planning to use parallel manipulators, which will give the joints the freedom
to move in multiple directions & orientations. An admittance control
strategy allows the exoskeleton to capture the user’s movements during combat
training & implement the same in real battle & survival conditions. In
future, the concepts of artificial intelligence & augmented reality can be
explored to make the exoskeleton more productive & smart, ultimately
proving to be a great weapon in battle & helping hand in adverse
conditions.

Questionnaire
: –  

a)      What
is your motivation behind participation?

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We
came to know about the competition from the college. The theme of the
competition fascinated us a lot and our dream to contribute to nation through
our knowledge came true with the organisation of this competition. It was one
of the major and driving motivations to participate in the event.

 

b)      What
are your specialized knowledge and expertise?

Our
team comprise of four members. Two of us are expertise in electrical
engineering and other two in mechanical engineering with computer
specialisation. We all possess knowledge about SoftWares like Ardunio IDE,
Eagle, Android studio, AutoCad, Circuit Maker,

 

c)      Previous
participation/awards/recognition if any

We
as team members have participated in Smart India Hackathon 2017 ( Finalists).

Most
of the members have participated individually in following competition as
whole:

·        
IEEE Region 10
Humanitarian Technology Conference, 2016 organised by Texas Instrument

·        
 

 

d)     What
are you planning to exhibit?

We
are planning to exhibit Scientific paper with a poster and simulation.We may
also present mock up model of our idea.

 

 

MULTIFUNCTIONAL EXOSKELETON

1.
INTRODUCTION

Powered exoskeletons (hereafter referred as robotic exoskeletons or just
exoskeletons) are wearable robots attached to subject’s limbs, in order to
replace or enhance their movements. They should be compliant with the user’s
movements and deliver at least part of the power necessary to accomplish the
movements.

 

For decades engineers and scientists have dreamed to brought to real
life an exoskeleton that could boost human strength, turning an ordinary person
into a “superhuman”. With the current miniaturized and powerful computer and
communication system, it is now possible to develop advanced control
architectures. New technology also created small and powerful actuators that
can be embedded in portable devices. New power sources have been investigated
and are now making possible to increase the autonomy of untethered devices. All
these advances in technology are becoming real the dream of bringing to life
the robotics exoskeletons.

Military exoskeletons are intended to be used by soldiers in the
battlefield or in rescue activities. They are aimed to augment the strength and
endurance of soldiers, making possible for them to carry heavy loads, walking
longer distances, etc.

 

2.1 Mechanical Design

The exoskeleton design is lightweight, i.e. about 9 kg. It is conceived
as a bilateral wearable device with six DoF (Degrees of Freedom), in which hip,
knee and ankle are powered joints. The gait cadence is expected to reach up to
0.5 m/s (1.8 km/h). Aluminum and stainless steel are primarily used in
the mechanical structure to account for mechanical resistance and reduced
weight. For further decrement of weight carbon steel can also be used. The
exoskeleton frame has bilateral uprights for the thigh and the shank, hinged
hip, knee and ankles and articulated footplates (distally) and waist area
(proximally).

 

 JOINTS:

To support the rotating components of the electric joint, there are
three groups of bearings:

 

(i) Main joint bearings. These bearings provide the relative rotation
between the joint’s proximal and distal links. They support significant
off-axis moments, but operate at very low speeds. Two angular contact bearings
create a compact, high-moment-capacity bearing set. Since they are constrained
as a pair, the races of an identical bearing provide a very precise spacer to
prevent uneven loading of the two bearings.

 

(ii) Motor shaft bearings. While these bearings do not see much loading,
they need to operate at high speeds.

 

(iii) Torque link bearings. Due to the unique torque sensing method
implemented the additional torque link also needs to be supported on bearings.
This link is low speed and does not see any large off-axis moments; therefore,
a single X-contact bearing supports the torque link

 

The electric exoskeleton joints are designed to be cooled via a liquid
cooling channel built into the mechanical structure as close as possible to the
motor stator’s steel structure. When necessary, coolant is pumped into each
joint, around the hot motor and then up to a radiator to cool it back down.

 

DC motors meet the criteria of necessary power with a compact and
portable solution for wearable devices. Within the DC motors category,
brushless motors offer several advantages for wearable devices, including
higher efficiency, more torque density, increased reliability, reduced noise,
longer lifetime and reduction of electromagnetic interference. Based on these
important characteristics, brushless DC motors were selected. Moreover, the
selected motors are flat type. This characteristic brings the possibility of placing
the motors coaxially with the joints and maintaining a small volume on the side
of the leg.

 

A 90 W DC motor (Maxon EC90-90W) is used in both hip joints. This motor has
a rated voltage of 24 VDC and nominal torque of 390 mNm.

 

POWER DRIVE FOR EXOSKELETON

Exoskeleton suit
problems need to be overcome if we are to fully realise this technology. Chief
amongst these areas is the power source. Currently, there is no way of
providing power to these suits for extended periods of time. Biomechanical energy harvesting from human motion
offers a promising clean alternative to electrical power supplied by batteries
for long duration of hours. Beside the traditional battery supply, we will incorporate
following in our model:

When
we walk, we generate most of the power from the hip when we push off. Then, as
the leg swings forward, the small muscles in our knees and elsewhere rest
before making sure our feet hit the ground at the desired spot. That
free-swinging technique saves energy. It can be incorporated it into their
exoskeletons.

 Heat generated in exoskeleton can be used to
create charges and convert to electricity to supply to suit via thermoelectric
material. Current
thermoelectric energy conversion is completed largely through the use of the
Seebeck Effect. Thermoelectric devices generate energy when there is a
difference between the heated surface and the environment. Qualitatively,
more electricity would be generated by a device if used in a colder
environment.

The combination
of limited energy and the large weight of batteries poses the most critical problem
for exoskeleton having high electricity demand. To overcome this problem,
energy can be extracted from the mechanical energy from the vertical movement
of the load during walking and converts it to electricity for powering device. the
vertical movement of a heavy load in the gravitational field during walking
represents a heretofore untapped source of mechanical energy and a potential
opportunity to generate substantial levels of

electricity. During
walking, a person moves like an inverted pendulum (4, 5, 9): One foot is put
down and then the body vaults over it, causing the hip to move up and down by 4
to 7 cm. Thus, if one is carrying a load in a backpack, because it is fixed to
the body, it has to go up and down the same vertical distance. In the case of a
36-kg load, 18 J of mechanical energy transfer (or work) accompanies each step
(assuming 5 cm displacement), and at two steps s-1this is equivalent
to 35 W.

 

DATA BUS

All sensors are connected to small custom-made electronic boards located
on each joint. This approach minimizes the amount of wires, cables and
connections in the exoskeleton. A second CAN bus connects all six joints to the
embedded computer that controls the exoskeleton.

The boards, here called JointCAN, contain all the circuitry for the
analog filters for each joint sensor and also the amplifiers for the strain
gauges. After filtering and amplifying, the signals are digitalized by a DSP
microcontroller and sent to the CAN bus.

The microcontroller used in the JointCAN boards is a Microchip
DsPIC30F4013. It works at 16 MHz of clock and digitalizes the analog sensors
input with 12 bits.

 

HEARTBEAT
MONITORING:

An ecg sensor
will be installed in the exoskeleton so as to monitor the health and awareness
of the soldier. This sensor will send data collected with the help of Bluetooth
and the complete information will be saved on the cloud of the department. If
the heartbeats fall below a particular level, medical level will be sent
immediately.

 

BULLET
PROOF VEST:

A bullet proof
vest is incorporated in our exoskeleton. The
suits will be made with a “liquid body armor”
that transforms into solid within milliseconds when a magnetic field or an
electric current is applied through the material.  The material
can be turned from liquid to solid (or vice versa) in 1/10th of a second. A
Polish company, Moratex, is working on a similar kind of liquid body armor, using a non-Newtonian
liquid called Shear-Thickening Fluid
(STF). So this concept can be adopted by us too.

 

AUTOMATION:

The
armour will be completely controlled by mind waves so as to decrease the pyysical
stress. In order to control the exoskeleton, the soldiers’ helmet will be
covered in small electrodes that cling to their scalps. The skullcaps are the
tools that connect the subject’s brain to the exoskeleton and are commonly used
in electroencephalograms
(EEGs) — a method of recording
electrical activity by placing conductive materials on the scalp (the brain
waves are then plotted on a chart, much like heart rate).  the EEG cap is used to
pick up very particular brain signals — those created by what the researchers
call steady-state visual evoked potentials (SSVEPs).

 

SENSORS:

The exoskeleton is equipped with two types of sensors: kinematic and
kinetic.

Kinematics sensors are used for measuring angular position, velocity and
acceleration; kinetic sensors measure the force of interaction between user’s
limb and exoskeleton. Moreover sensors like EEG sensor, ECG sensors, heat
sensor etc are also used.

 

 

 

 

 

 

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