EMG Based Arm Mounted Exoskeleton

Project Title

EMG Based Arm Mounted Exoskeleton

Project Area of Specialization Electrical/Electronic EngineeringProject Summary

Muscular degeneration is a global disease. It is widespread not just in Pakistan, but all over the world. Diseases like Amyotrophic Lateral Sclerosis (ALS), Parkinson's, Multiple Sclerosis, and so on can massively hinder movement, and leave the patient with minimal control over their limbs. Furthermore, even without the affliction of these diseases, old age comes for everyone, and with it, difficulty in motion. 

People with muscle degeneration thus do not have much hope of rehabilitation with the current solutions. The prosthetics currently available are mainly for amputees, i.e., people who have lost parts of their limbs. However, prosthetics for muscle degeneration patients are mostly in the prototype and testing stages and haven’t been widely commercialized yet. These structures are heavy, inaccurate, and mostly button controlled. Even among the exoskeletons that have been commercialized, high cost makes them unsuitable for everyday use.

Through our electromyography driven Medical and Industrial Lightweight Exoskeleton (EMG-MILE), we aim to rectify these issues, at least partly. Using a particular device, called the EMG sensor, we aim to create an exoskeleton for one arm that will provide a means of rehabilitation at a low cost as well as high accuracy and portability. The usage of the EMG sensor makes the entire device, to all intent and purposes, brain controlled, which makes it much more user friendly, and removes the hassle of using a button to control movements. We will classify a particular motion, that of the flexion/extension of the forearm, and use it to facilitate the motion of picking up an object. A motor will be used to implement the motion, with its specifications deciding the amount of weight that can be lifted. The aim is to be able to comfortably lift a minimum of 5 kg.

Project Objectives

The objectives of the project are as follows:

• Make a CAD model of an exoskeleton for one arm, with the aim to make it as comfortable and lightweight as possible for the user.
• 3D print the aforementioned model, with the desired characteristics aimed to be implemented through use of a sturdy but lightweight material like PLA for printing.
• Classify the motion of lifting specifically through elbow flexion (contraction/extension of the bicep).
• Bring about the movements of the exoskeleton through a motor of appropriate size and weight.
• Implement all above features while keeping the overall cost down as much as possible without compromising on targeted features and quality.

Project Implementation Method

The project can be broken down into the following steps for implementation:

• For the CAD model, the software we opted for was Autodesk Fusion 360, due to its accessibility for beginners. Fusion 360 is easier to learn to use for new users as compared to other popular modeling softwares like Solidworks, while having a similarly wide range of functions and features. Most importantly, it has an extremely active online community, who are always available for help and support should a person run into any difficulties.
• For 3D printing, we opted to use a type of plastic, PLA, as the printing material. PLA is among the most commonly used materials for 3D printing due to its environment friendly nature, as well as its relative durability and less weight. That makes it perfect for our use.
• For capturing the muscle impulse signals, we opted for Surface Electromyography (EMG) electrodes, instead of a possible set of alternatives ranging from Electroencephalography (EEG)/Electrocorticogram (ECoG) signals or simply intramuscular EMG electrodes. This choice was made keeping in mind the aims and objectives of the project with respect to levels of comfort, accuracy, affordability etc.
• The EMG sensors are powered by two rechargeable 9V batteries.
• For the signal acquisition, processing, amplification, and classification, we are using Arduino and MATLAB since they are easy to use and implement and have good appropriate libraries available.
• For the movement of the structure, we are using a power window motor. Besides being light and small, it provides a high amount of torque. These characteristics make it ideal for our purposes.
• Since it is a DC motor which only provides motion in one direction, we are using the BTS7960 motor driver, which consists of an h-bridge, that allows the DC motor to turn in both directions.
• The motor itself is powered by a rechargeable Li-Po battery.
• Finally, integration of all the different components is done to make the final product, which is then tested for its functionalities.

Benefits of the Project

Benefits of the project include:

• Making available an affordable exoskeleton for people with muscle diseases centered on their arms, with an aim at giving them an opportunity to regain the use of their limbs.
• Since the structure performs a motion assist role, it allows users to lift much heavier weights than they would otherwise be able to, and for a longer time, without feeling any kind of fatigue.
• Besides being much more affordable as compared to typical exoskeletons in the market, the structure will also be extremely lightweight, comfortable, and portable, with the user's ease when it comes to wearing it a priority.
• While typical prosthetics are button controlled, our project uses EMG sensors, thus automatically sensing the motions the user wishes to make and removing the hindrance of having to push the button every time. This automates the entire process, again bringing about ease of use.
• Lastly, while the structure is at present aimed at medical use, the design is very scalable and can easily be extended to be able to support much heavier weights. This would enable it to be used in industrial applications requiring augmented strength.

Technical Details of Final Deliverable

The final deliverable consists of the 3D printed arm-mounted exoskeleton, constructed of a kind of plastic, Polylactic Acid (PLA). It can lift a minimum weight of 5 kg.

Besides the above mentioned details, some specifications of the hardware in the final deliverable include:

• 1 x Arduino Uno R3
• 1 x Toyota Denso Power Window Motor
• 1 x IB2 BTS7960 Motor Driver
• 1 x 5200 mAh 11.1V 3S 30C Li-Po Battery for Motor
• 1 x XT60 500V 30A Male & Female Bullet Connectors
• 1 x Deans T-Plug T-Connector Male/Female Pair 50 A
• 1 x EMG Muscle Sensor v3 by Advancer Technologies for Arduino
• 3 x ECG/EMG Electrodes
• 2 x 300 mAh Ni-MH Rechargeable 9V Battery for EMG Sensor

Final Deliverable of the Project HW/SW integrated systemCore Industry MedicalOther Industries Health Core Technology Wearables and ImplantablesOther Technologies 3D/4D Printing, RoboticsSustainable Development Goals Good Health and Well-Being for PeopleRequired Resources

Item Name	Type	No. of Units	Per Unit Cost (in Rs)	Total (in Rs)
			Total in (Rs)	53604
3D Print of Exoskeleton	Equipment	2	5000	10000
Power Window Motor	Equipment	1	800	800
BTS7960 Motor Driver	Equipment	1	1400	1400
Rechargeable 9V Battery	Equipment	2	950	1900
9V Battery Snap Connector	Equipment	3	18	54
9V Battery Charger	Equipment	1	400	400
EMG Muscle Sensor for Arduino	Equipment	4	5000	20000
Rechargeable Li-Po Battery	Equipment	2	4550	9100
Li-Po Battery Charger	Equipment	1	650	650
Deans T-Plug T-Connector Male/Female Pair	Equipment	1	60	60
Arduino R3 with Cable	Equipment	1	1450	1450
ECG/EMG Electrodes	Equipment	2	650	1300
Shipping	Miscellaneous	2	250	500
A1 Poster	Miscellaneous	2	360	720
Poster Framing	Miscellaneous	2	1100	2200
Motor Gear Extension	Equipment	1	500	500
XT60 Male & Female Bullet Connectors	Equipment	1	70	70
Shoulder Harness	Miscellaneous	1	2500	2500