INTRODUCTION TO ARM PROSTHESIS - CiteSeerX

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

6464(Print), ISSN 0976 – 6472(Online), Volume 5, Issue 10, October (2014), pp. 45-54 © IAEME

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ADVANCES & DEVELOPMENT IN BIOMECHATRONICS-

INTRODUCTION TO ARM PROSTHESIS

Prof. Shriniwas Metan1, Prof. Rahul Bhandari

2, Azeem Dafedar

3,

Vinay Bangartale4, Pankaj Ande

5

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:

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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.



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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

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

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


6472(Online), Volume 5, Issue 10, October (2014), pp. 45-54

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user's nervous and/or muscle system. The biosensor relates this information to a controller located


the limb and actuator (such as the limb position and applied force) and relate this informa


(which detect an electric current produced by chemical means) on the

skin, needle electrodes implanted in muscle, and/or solid-state electrode arrays with nerves growing


force and load) and relate to the biosensor and/or the controller. These are mechanical devices such

as force meters and accelerometers.

with the user's nerve or muscle system and the device. It relays



ller also monitors and controls the movements of the Biomechatronic device.


motor that aids or replaces the user's native muscle depending upon whether the device is orthotic or

MECHATRONICS

Block Diagram showing the Fields of Biomechatronics

is a large field with a combination of Biology, Mechanical and Electronics.


artificially assist human movement without replacing the impaired limb.

, "appliance", or simply brace is an orthotic device used to:


4 © IAEME


biosensor relates this information to a controller located


the limb and actuator (such as the limb position and applied force) and relate this information to the


(which detect an electric current produced by chemical means) on the

state electrode arrays with nerves growing


ntroller. These are mechanical devices such

the user's nerve or muscle system and the device. It relays



device.


upon whether the device is orthotic or

mechatronics

is a large field with a combination of Biology, Mechanical and Electronics.


artificially assist human movement without replacing the impaired limb.

device used to:



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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



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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]

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



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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



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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

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.



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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”,


(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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