Compressed Air Powered Human Exoskeleton Suit for Material Handling and Disaster Management (DRUSE 2018)

Team Leader: Bhushan Darekar

Team Members: Prabhakar Naik, Jayant Unde, Manthan Pawar, Sushant Soude

Under the guidance of Dr S. S. Ohol.

I worked on the conceptual model design of full body exoskeleton, Development of Control Enabled Rachet Joint, Electro Pneumatic System, Development of PAM, I also worked on the system integration and to develop the control algorithm for the exoskeleton.

Skills Used are Solidworks, Rapid Prototyping, Fabrication Techniques, Arduino, Electronics and Programming

As biomechatronic technology has matured over the past fifty years, exoskeletons have emerged as leading tools for enhancing able-bodied performance, assisting human mobility, and restoring lost limb function. These systems are anthropomorphic, structural devices that work, in conjunction with the body’s natural architecture to aid limb mobility. Exploiting biometric design, the device may be worn in close proximity to the body and transmits torques via powered revolute joints and structural limbs. Controllable, wireless exoskeletons offer significant potential in restoring lost limb function, and enhancing mobility and strength of the user. Previous exoskeleton development has largely been part of major research endeavours and has yielded solutions exhibiting high inertia limbs which are burdensome to the wearer. In order to make this sophisticated technology accessible to a material handling and disaster management for the soldiers, my team has designed and created a proof of concept of Compressed Air Powered Human Exoskeleton Suit for Material
Handling and Disaster Management.

This Exoskeleton is using Pneumatic Artificial Muscle to power upper body of the suit and passive lower body suit with control enable locking mechanism is used to transfer force through the links to ground also this exoskeleton is equipped with sensors as to work autonomously with onboard power supply.

 As students of Engineering, we always extract ideas from entertainment sources such as movies and comics. The idea of making exoskeleton came from the movie Ironman. The idea could be correlated to an increasing number of applications for an exoskeleton, such as decreased fatigue and increased productivity whilst unloading supplies or enabling a soldier to carry heavy objects while running or climbing.

Technical Details:

An exoskeleton is an artificial body suit that enables wearer with ability enhancing properties such as inhuman strength, enhanced work durability, functioning as armour, superior capabilities that would be impossible to obtain otherwise. There are different types of exoskeletons depending on the requirement of external power source and capabilities
1)Passive Exoskeleton:
Does not require a power supply, requires human effort, Harnesses body power and save
energy, helps us in posture, Lightweight and easy to use.
2)Powered Exoskeleton:
Requires power supply, does not require human effort, big and heavy, helps to do jobs which
are not humanly possible
3)Haptic Exoskeleton:
Used in graphics, used to capture motions accurately, used in virtual reality We are developing an exoskeleton which is a combination of a powered and passive exoskeleton. In our proposed model upper body exoskeleton is consist of pneumatic artificial muscle (PAM) which is actuated by compressed air supply. Lower body exoskeleton structure consists of two-way ratchet and pawl mechanism controlled by servo motor at the joints of hip and knee and ankle, enables it to engage when necessary depending on the force sensor feedback.

a) Pneumatic Artificial Muscle:

Pneumatic artificial muscles (PAMs) are contractile or extensional devices operated
by pressurized air filling a pneumatic bladder. Silicone Rubber Tube and Braided Nylon Sleeve
used to manufacture PAM.
Advantages of using PAM are:
• Flexible than the traditional Actuator
• Power to weight ratio is Higher
• Light in Weight and Fast Actuation speed
• PAM can be manufactured in any size
• Low cost compares to pneumatic pistons and hydraulic systems.

b) Structure:

Most of the existence exoskeletons use metallic body which makes them heavy. We are planning to use Fiber Reinforced Polymer body and some aluminium components in our prototype thus to make exoskeleton Lightweight and user-friendly. One more Advantage to use Flexible Actuator is it cannot restrict Motion and Degree of freedom of Wearer while non actuated condition and in that case user can pick up lightweight objects without powering up the suit.

c)Pneumatic System:

A pneumatic system used in exoskeleton consists of on-board lightweight air tank. 3/2 normally closed direction control valves 12-volt dc are used to supply air in PAM. Pressure relief valves are used to control operating pneumatic Air pressure below 6 Bar by considering the safety of the system. Onboard Filter Regulator and Lubricator unit are used to condition the air going into the PAM.

d)Electronics:

We are using Arduino Open Source Platform to operate the Exoskeleton in Autonomous mode. A controller on the system is taking feedback from the force sensor to control the joints at hip, knee and ankle and flex sensor (resistive type) are used to take feedback from the hand motion real time to actuate the Pneumatic Artificial Muscle when user trying to lift the weight. Battery system used in Lithium polymer battery pack 24-volt 6 s 8000mah. A battery will power up all the electronics on the system that are Direction Control Valves, Microcontroller, Relay Board and Servo motors.

e) Straps and Belts:

Strap and belts are used to attach the exoskeleton to the user quickly. Straps and belts give an advantage that they can be used to strap the same exoskeleton to different sizes of a wearer. They save a lot of fatigue of customizing the sizes of exoskeleton according to a size of the wearer. Straps used are Velcro type and harness types for easy wearing and removing of exoskeleton that will save a lot of time.

 1) Presented a paper titled “Lower Body Passive Exoskeleton Using Control Enabled Two Way Ratchet” in the 9th International Conference on Computing, Communication and Networking Technologies (ICCCNT) 2018 held at IISC Bangalore.

2)Accepted  & will be presenting the paper titled “Pneumatic Artificial Muscle Powered Exoskeleton” in a 11th International Conference on Computer and Automation Engineering (ICCAE)2018 will be held in Perth, Australia.