Advances and development in biomechatronics introduction to arm prosthesis

International INTERNATIONAL Journal of Electronics and Communication JOURNAL Engineering OF ELECTRONICS & Technology (IJECET), AND
ISSN 0976 –
6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 45-54 © IAEME
COMMUNICATION ENGINEERING TECHNOLOGY (IJECET)
ISSN 0976 – 6464(Print)
ISSN 0976 – 6472(Online)
Volume 5, Issue 10, October (2014), pp. 45-54
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ADVANCES DEVELOPMENT IN BIOMECHATRONICS-INTRODUCTION
45

TO ARM PROSTHESIS
Prof. Shriniwas Metan1, Prof. Rahul Bhandari2, Azeem Dafedar3,
Vinay Bangartale4, Pankaj Ande5
1, 2,3,4,5 Department of Mechanical Engineering, N.K. Orchid College of Engineering Technology,
Solapur, Maharashtra, India
ABSTRACT
Now a day’s modern robotics is inching ever closer to this vision in a field known as
Biomechatronics. Biomechatronics is the merging of man with machine, like the cyborg of science
fiction. It is an interdisciplinary field encompassing biology, neurosciences, mechanics, electronics
and robotics. Biomechatronic scientists attempt to make devices that interact with human muscle,
skeleton, and nervous systems with the goals of assisting or enhancing human motor control that can
be lost or impaired by trauma, disease or birth defects. It is a vast branch containing the fields of
Orthotics and Prosthetics. Orthotics deals with supporting the weaker part of the body, whereas
Prosthetics enables the use of impaired limbs or even provide artificial limbs to an amputee with the
help of Mechatronics. In the current work a successful attempt is made to emphasize the latest
prosthetic bionic hand that has come up in order to serve the amputees. Also, it is ensured to
concentrate on the point of how the arm prosthesis works. Right from an initial experiment
conducted by Hugh Herr and his colleagues explaining the working of a swimming robot, which was
initiated by frog muscles to a hand like artificial hand for amputees.
Keywords: Articulations, Biosensors, Bio Mechatronics, Orthotics, Prosthetics, Prosthetic Motors,
Tactile Sensors.
1. INTRODUCTION
Biomechatronics is an applied interdisciplinary science that aims to integrate mechanical
elements, electronics and parts of biological organisms. It includes the aspects of biology,
mechanics, and electronics. Consider what happens when you lift your foot to walk:

International Journal of Electronics and Communication Engineering Technology (IJECET), ISSN 0976 –
46

i. The motor center of your brain sends impulses to the muscles in your foot and leg. The
appropriate muscles contract in the appropriate sequence to move and lift your foot.
ii. Nerve cells in your foot sense the ground and feedback information to your brain to adjust the
force, or the number of muscle groups required to walk across the surface. For example, you
don't apply the same force to walk on a wooden floor as you do to walk through snow or mud.
iii. Nerve cells in your leg muscle spindles sense the position of the floor and feedback
information to the brain. You do not have to look at the floor to know where it is.
iv. Once you raise your foot to take a step, your brain sends appropriate signals to the leg and foot
muscles to set it down.
This system has sensors (nerve cells, muscle spindles), actuators (muscles) and a controller
(brain/spinal cord). Further, the experiment conducted by Dr. Hugh Herr, following which a journal
was published titled “A Swimming Robot Actuated By a Living Muscle Tissue” [1] was a conclusive
proof that the experiment was nothing but a giant leap in the field of initiating mechatronic
components with the help of our living tissue. Any amputee can surely benefit themselves with
technology that Dr. Hugh Herr, his team and their hardships have come up with,
“BIOMECHATRONICS”.
2. LITERATURE SURVEY
Several laboratories around the world conduct research in biomechatronics, including MIT,
University of Twente (Netherlands), and University of California at Berkeley. Current research
focuses on three main areas:
2.1 Analyze Human Motions
We must understand how humans move so that we can design biomechatronic devices that
effectively mimic and aid human movement. Dr. Peter Veltink [2] and colleagues at the University of
Twente analyzed walking movements (gait analysis) by measuring body movements with camera
systems, ground reactive forces [3] with force meters, and muscle activity with electromyograms. The
above done analysis helped group to understand the free walking motions and the diagnosed ones.
Veltink's group similarly evaluates balance control while walking and standing. Dr. Hugh
Herr's Biomechatronics group at MIT [4] used computer models and camera analyses of movement to
study balance, leg retraction during running, and angular momentum conservation during walking.
2.2 Interfacing Electronic Devices with Humans
An important aspect that separates biomechatronics devices from conventional orthotic and
prosthetic devices is the ability to connect with the nerves and muscle systems of the user so he can
send and receive information from the device.
2.3 Test ways of using living muscle tissue as actuators for electronic devices
Most actuators that are used in orthotic and prosthetic devices are electrical motors or
electrical wires that shrink when current is passed through them. While these devices can provide
contractile force, they do not come close to mimicking the dynamic flexibility of living muscle
tissue. For any prosthetic device we need to cross check all the parameters related to the working of
the electronic devices incorporated in the bionic hand and so, for which Dr. Hugh Herr and his
colleagues made a robotic fish that was propelled by living muscle tissue taken from frog legs.

47

Fig. 1: Robotic fish prototype [5]
Fig. 2: Schematic Diagram of the Robotic Fish Prototype [5]
The robotic fish was a prototype of a biomechatronic device with a living actuator. Following
characteristics were given to the fish:
i. A Styrofoam float (F) so the fish can float.
ii. Electrical wires (W) for connections.
iii. A silicone tail (T) that enables force while swimming.
iv. Power provided by lithium batteries (B).
v. A microcontroller to control movement (C).
vi. An infrared sensor enables the microcontroller to communicate with a handheld device (C).
vii. Muscles stimulated by an electronic unit (C).
3. BIOMECHATRONIC COMPONENTS
As stated above Dr. Hugh Herr and his acquaintances made a robotic fish that was propelled
by living muscle tissue which was taken from frog legs which intended on using sensors,
microcontroller, batteries, etc. Similarly, any biomechatronic system must have the same types of
components [6], like:
Fig. 3: Block Diagram showing the Biomechatronic Components

International Journal of Electronics and Communication Engineering Technology
6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp.
3.1.1 Biosensors

(IJECET), ISSN 0976 –
4 © IAEME
Depending upon the impairment and type of device, this information can come from the
user's nervous and/or muscle system. The
either externally or inside the device itself, in the case of a prosthetic. Biosensors also feedback from
the limb and actuator (such as the limb position and applied force) and relate this informa
controller or the user's nervous/muscle system. Biosensors may be wires that detect electrical activity
such as galvanic detectors (which detect an electric current produced by chemical means) on the
skin, needle electrodes implanted in muscle,
through them.
3.1.2 Mechanical Sensors
biosensor relates this information to a controller located
and/or solid-state electrode arrays with nerves growing
Mechanical sensors [7] measure information about the device (such as limb position, applied
force and load) and relate to the biosensor and/or the co
as force meters and accelerometers.
3.1.3 Controller
The controller interfaces
and/or interprets intention commands from the user to the actuators of the device. It also relays
and/or interprets feedback information from the mechanical and biosensors to the user. The
controller also monitors and controls the movements of the
3.1.4 Actuator
The actuator is an artificial muscle that produces force or movement. The actuator can be a
motor that aids or replaces the user's native muscle depending
prosthetic.
3.2 FIELDS OF BIOMECHATRONICS
Fig. 4: Block Diagram showing the Fields of Bio
Biomechatronics is a large field with a combination of Biology, Mechanical and Electronics.
There are two large areas which are concerned with this field amongst which it has proved to be a
boon to the mankind, which are:
a. Orthotics
b. Prosthetics.
3.2.1 Orthotic Devices
They artificially assist human movement without replacing the impaired limb.
An orthopaedic brace, appliance, or simply
45-54
48
controller. These are mechanical devices such
with the user's nerve or muscle system and the device. It relays
ller Biomechatronic device.
upon whether the device is orthotic or
MECHATRONICS
Biomechatronics
, brace is an orthotic device used to:
information to the
ntroller. mechatronics

49

i.) Control, guide, limit and/or immobilize an extremity, joint or body segment for a particular
reason.
ii.) To restrict movement in a given direction.
iii.) To assist movement generally.
iv.) To reduce weight bearing forces for a particular purpose.
v.) To aid rehabilitation from fractures after the removal of a cast.
vi.) To otherwise correct the shape and/or function of the body, to provide easier movement
capability or reduce pain.
Scientists have continuously been working on the orthotic devices. Investigators at the
University of California at Berkeley have developed a machine or exoskeleton to enhance the
walking ability of a normal human. The Berkeley Lower Extremity Exoskeleton (BLEEX) [8] uses
metal leg braces that powered by motors to make it easier for the wearer to walk. Sensors and
actuators in the device provide feedback information to adjust the movements and the load while
walking. The device's controller and engine are located in a vest attached to a backpack frame. While
the device itself weighs 100 pounds, it enables a person to haul a 70-pound backpack, while feeling
as if he/she is merely carrying 5 pounds.
Fig 5: BLEEX [8]
3.2.2 Prosthetic Devices
The Egyptians were the early pioneers of prosthetic technology. Their rudimentary, prosthetic
limbs were made of fiber and it is believed that they were worn more for a sense of “wholeness” than
function. In addition to lighter, patient-molded devices, the advent of microprocessors, computer
chips and robotics in today's devices are designed to return amputees to the lifestyle they were
accustomed to, rather than to simply provide basic functionality or a more pleasing appearance.
Prosthesis is more realistic with silicone covers and is able to mimic the function of a natural limb
more now than at any time before. In exploring the history of prosthetics, we can appreciate all that
went into making a device and the generations of perseverance required to ensure that man can not
only have four limbs but that he can have function.[9]
Prosthetic devices artificially assist human movement replacing the impaired limb with the
biomechatronic device. Prosthesis can basically be achieved in 3 regions like arm, knee chest.
4. ARM PROSTHESIS
The primary purpose of an arm prosthetic is to mimic the appearance and replace the function
of a missing limb. While a single prosthetic that achieves both a natural appearance and extreme
functionality would be ideal, most artificial limbs that exist today sacrifice some degree of one for
the other. As such, there is a wide spectrum of specialized prosthetics that range from the purely

cosmetic (which are inert) to the primarily functional (whose appearance is obviously mechanical).
Myoelectric prosthetics are an attempt to serve both purposes of an artificial limb equally, without
sacrificing appearance for functionality. [10]
50

An example of a person with a stump muscle will have to be considered for understanding
the need of arm prosthesis, Claudia Mitchell[11], a former Marine and amputee, has tested a prosthetic
arm developed by Dr. Todd Kuiken at the Rehabilitation Institute of Chicago. A plastic surgeon, Dr.
Gregory Dumainian at Northwestern Memorial Hospital in Chicago redirected the nerves that control
her missing arm to her chest. The nerves re-grew close to the skin of her chest. Tiny electrodes on
her skin pick up the electrical activity of these nerves and send signals to the motors in the arm. She
is able to control the arm's movements by thinking about it.
Fig 6: The First Bionic Arm [11]
Previously used Myographic arms were on the principle of utilizing the electric residual
neuro – muscular system of human body to control functions of the electric powered prosthetic
devices. The disadvantages of those hands were, mainly, restricted degrees of freedom, and the lack
of intelligent systems, like the feedback and the automatic grip, which is now present in the modern
hands. Presently, the Myographic hands are also known as the “Bionic Hands”. The new bionic
hands combine the ease of control; they comprise of individual speed motors for precise movements,
additional grip patterns, and more number of degrees of freedom.
5. CONSTRUCTION
The bionic hand consists of a pairs of sensors, Lithium-ion batteries and its required circuit
inside the mould. Further, a palm which consists of sensors at the intercarpel articulations i.e., the
bottom portion, precision motors at interphalangeal articulations and the metacarpophalangeal
articulations of the hand. Finally, it has an upper standard glove which gives a life like feel. The
material used for the mould is High Density Polypropylene and for palm Poly Vinyl Chloride is
used. The average weight of the hand is 1.5 kilograms and the length of the palm is between 190 –
200 mm. The maximum width of the palm is between 84 -92 mm. The diameter at the wrist is 50
mm and maximum opening width is 105 mm (with glove). [12]
Fig 7: Disassembled Bionic Hand

51
5.1 Prosthetic Motors (Stepper Motors)

Stepper Motors[12] are used in feedback control system as output actuator. The reason that
Stepper motor because unlike large induction motors, they are not used for continuous energy
conservation. Typical highlights of stepper motor are:
i.) Design, construction, mode of operation is different from other conventional motors.
Fig 8: Bionic Arm showing the position of Motors [13]
ii.) Power is from milliwatts to few hundred watts.
iii.) Low rotor inertia and high speed response.
iv.) Operate at low speed and sometimes at zero speed also.
Fig 5: Torsion Springs [14]
In the above figure, the finger movement mechanism is shown. It consists of a wire taking
one rotation on each pulley which is located on each of the metacarpophalangeal and interphalangeal
articulations [15] of each finger. The Pulley is coupled with the Torsional spring which is provided for
conserving the energy.
5.2 WORKING
i.) Motor Cortex in Cerebrum: The Motor Cortex[16] is located exactly at the center of the
Cerebrum, which is located at the center of the Brain. The function of the Motor Cortex is to
generate the impulses, and also they house the nerves.
Fig 6: Block Diagram of travelling impulses

ii.) Cerebellum: The cerebellum (Latin for little brain) is a region of the brain that plays an
important role in motor control. It may also be involved in some cognitive functions such
as attention and language, and in regulating fear and pleasure responses, but its movement-related
functions are the most solidly established. The cerebellum does not initiate movement, but it
contributes to coordination, precision, and accurate timing.
iii.) Neuro Signals: These are very small electric signals ( 50μV) generated in the motor Cortex
and which are passed to every part of the body.
iv.) Stump Muscles: It is the extremity of the limb after amputation (intentional removal of the
limb to remove diseased tissue).
v.) Acetylcholine: It is the neuro-transducer which performs the work of the transducing the
impulses, resulting in the actuation of the muscle.
vi.) Biosensors: The biosensor relates the impulses to a controller located either externally or
inside the device.
vii.) Bionic Hand: The modern prosthetic device using all the above, gives a better life to the
impaired person.
5.2.1 WORKING PRINCIPLE OF BIONIC HAND
52

The signals (impulses) required for working of the hand is generated in the Motor Cortex of
the Cerebrum. The impulses then come to Cerebellum for refining and then these refined impulses
are passed to the hand muscles via. Nerves. For the initiation of muscle movement a potential
difference is required which is developed by the Acetylcholine at the muscles and which is picked up
by the biosensors at the inner surface of the bionic hand.
Fig 6: Block diagram of working process of bionic hand
The potential difference picked up by the biosensors is very small (in μV) and which is
amplified and passed to the prosthetic motors for movements. When a positive signal is given to the
prosthetic motor, the finger bends forward in a gripping motion. Now, the torsional springs stores the
energy and uses it when the motor is in OFF position, which is required to retain certain position.
Also, Tactile Sensors [18] are placed on all the fingers. Tactile sensors give a fine grained sense of
touch which make possible to handle objects more reliably and more safely.

53

Fig 7: Position of the Tactile sensors [17] [19]
The bionic hand gives various motions of the palm [20], some of which are as follows:
a. Open Palm b. Pointing Finger c. Tripod Grip
Fig 8: Different positional movements of the bionic hand
Apart from these, various other grips are Pinch Grip, Precision Grip, Finger Adduction,
Power Grip, Hook Grip, Column Grip, Trigger Grip, Key Grip, Mouse Grip and Relaxed Hand
Position.
6. CONCLUSION
Primitive Biomechatronic devices have existed for some time; the heart pacemaker and the
defibrillator are its examples. More exciting Biomechatronic possibilities that scientists foresee in the
near future include pancreas pacemakers for diabetics, mentally controlled electronic muscle
stimulators for stroke and accident survivors, cameras that can be wired into the brain allowing blind
people to see, and microphones that can be wired into the brain allowing deaf people to hear. The
mixture of electronics and mechanics for the application in the field of biology has given marvelous
results like the bionic hand. A successful attempt has been made to explain the bionic hand which
has the advantage of more number of degrees of freedom, light in weight, previously programmed
microprocessor with a facility of concern, it comes with a hand looking glove giving people an
option of continuing their lives just like before. The successful attempt of scientists has resulted in
giving a better life to the people suffering with impaired muscles. The further research which could
make these products even better is the improvements in the mould. The mould could be made like a
sleeve, wherein, it would hold the stump and the bionic hand, plus it would follow the contour of
hand.
7. ACKNOWLEDGEMENT
We sincerely thank Dr. Bhagwat and his team of Niramay Hospitals and Dr. P.M. Kulkarni
for their immense contribution in the publication by sharing their knowledge time.

54
8. REFERENCES

[1] dspace.mit.edu open access journal.
[2] science.howstuffworks.com/biomechatronics2.htm.
[3] Ernesto CarlosMarteniz Villalpando, Thesis Paper on “Estimation of Ground Reaction Forces
and Zero Movement Point on a Powered Ankle – Foot Prosthesis” by. at Massachusetts
Institute of Technology, Cambridge.
[4] Herr, H.; Weber J.; Martinez-Villalpando, E.C.; Massachusetts Institute of Technology,
Cambridge.
[5] Herr, H.; Dennis, R.G.; “A Swimming Robot Actuated by a Living Muscle Tissue”;
Massachusetts Institute of Technology, Cambridge, October 2004; 4.
[6] Article by Craig Freudenrich, Ph.D. on “For Biomechatronic components: How
Biomechatronics Works”.
[7] W. Bolton; “Mechatronics: Electronics Control Systems in Mechanical and Electrical
Engineering”; Pearson Education; Pg no. 33-69.
[8] http://bleex.me.berkeley.edu/research/exoskeleton/bleex.
[9] http://www.amputee-coalition.org/inmotion/nov_dec_07/history_prosthetics.html.
[10] http://www.myoelectricprosthetics.com.
[11] http://io9.com/5532085/portraits-in-posthumanity-claudia-mitchell.
[12] http://bebionic.com/the_hand/technical_information.
[13] https://www.behance.net/gallery/850286/Dexterous-Myoelectric-Hand-Prosthesis.
[14] http://www.takanishi.mech.waseda.ac.jp/top/research/eyes/we-4rII/index.htm.
[15] Raoul Tubiana, Jean-Michel Thomine, Evelyn; Book on Anatomy of hand Examination of the
Hand and Wrist.
[16] Young, John Zachary (1964). A Model of the Brain. William Withering Lectures. Clarendon
Press. 31.
[17] http://www.takanishi.mech.waseda.ac.jp/top/research/eyes/we-4rII/index.htm.
[18] Characteristics of a New Optical Tactile Sensor for Interactive Robot Fingers by Bakri Ali
Muhammad, Azmi Ayub, Hanafiah Yussof.
[19] http://2008.iccas.org/program/digest view.asp.
[20] http://bebionic.com/the hand/grip patterns.
[21] Dr. Ashwin Patani and Prof. Miloni Ganatra, “Biomimetic Robots: Based on Ants”,
International Journal of Electronics and Communication Engineering Technology
(IJECET), Volume 5, Issue 2, 2014, pp. 57 - 68, ISSN Print: 0976- 6464, ISSN Online:
0976 –6472.
[22] Sreekanth Reddy Kallem, “Artificial Intelligence in the Movement of Mobile Agent
(Robotic)”, International journal of Computer Engineering Technology (IJCET),
Volume 4, Issue 6, 2013, pp. 394 - 402, ISSN Print: 0976 – 6367, ISSN Online: 0976 – 6375.
[23] Sumit A. Raurale and Dr. Prashant N. Chatur, “Evaluation of EMG Signals to Control
Multiple Hand Movements for Prosthesis Robotic Hand-A Review”, International Journal of
Electronics and Communication Engineering Technology (IJECET), Volume 4, Issue 6,
2013, pp. 124 - 133, ISSN Print: 0976- 6464, ISSN Online: 0976 –6472.

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