Design and fabrication of soft robotic hand with embodied sensing for motion impaired humans

Amputation is the clinical or accidental removal of a body limb, and it is considered one of the most frequently acquired impairments. According to the National Center for Health Statistics, there are 50,000 new amputations in the United States each year. In the United States, 41,000 people are regi

Project Title

Design and fabrication of soft robotic hand with embodied sensing for motion impaired humans

Project Area of Specialization

Robotics

Project Summary

Amputation is the clinical or accidental removal of a body limb, and it is considered one of the most frequently acquired impairments. According to the National Center for Health Statistics, there are 50,000 new amputations in the United States each year. In the United States, 41,000 people are registered have had their hands or entire arms amputated. The absence of an upper limb significantly impairs amputees' ability to perform daily life activities, having a great positive impact on their health and recovery.

A prosthetic limb that effectively replaces lost functions is capable of improving the quality of life of those who have lost limbs. There are many prosthetic hands available in the market but they are expensive, have rigid parts, less flexibility results in less grasping ability, they are heavier than the ordinary human hands in average, less durable, and more power-consuming.

Soft robotic hands are gaining popularity as robotic end effectors. They are safer for human-robot and environment–robot interactions. The inherent material compliance of soft robots makes them easier to control, simpler to design lightweight, cost effective and durable.

The project aims to design and fabricate a soft robotic hand with embodied sensing to improve the quality of life for motion-impaired people. A wearable soft robotic hand will assist patients to grasp objects of various shapes. Will help them perform routine activities who have lost the limb.

Project Objectives

• To design human inspired soft  hand actuators.

• To introduce tactile sensing feature in the hand actuator using flexible sensors.

• To design an algorithm for lifting specific objects using the actuator with maximum delicacy.

Project Implementation Method

CAD DESIGN:

First of all, we are going to design our prosthetic hand in any CAD software e.g AutoCAD or SolidWorks.

3D PRINTING:

Following the CAD design, we will use a 3D printer to print the prosthetic hand which is already available at Fab Lab Sukkur IBA. The “Fused Deposition Modeling (FDM) technique”, which is one of the best, will be used for 3D printing. The FDM method is surrounded by gaps in the hand structure, and the infill percentage in the 3D printer software can be used to change the size of these spaces.

3D printing can be done in two ways: either a single finger or the entire hand can be printed in the printer. The entire hand will take approximately 34 hours to complete. The 3D printed hand is made of a soft material. The flexible and soft material which is used for fabrication is “TPU90 (Thermoplastic Polyurethane with Shore 90A)”.

Actuation and Control system Assembly

We will install the actuation system in the palm of the hand once the hand has been printed. Five geared DC micro motors will be connected to the tips of fingers via threads or strings. Each finger is actuated by one of these five motors. A cable-driven mechanism will be used for the actuation of fingers. Tendon cables are wrapped around small reels and connected to the motors for each finger. A microcontroller based on the “Atmel 8-bit ATmega2560” and the “Freescale MC33926 H-bridge motor driver” will control these motors. The motor driver can supply nearly 3A constant current to a single brushed DC motor at 6V and can withstand peak currents of up to 5A per channel for a few seconds. The DC motors will be 9.5gr with no load speed of 30,000rpm and stall torque of 1Nm, which can be fitted with various gearheads of different ratios. The microcontroller will be responsible for commanding the hand to change the positions of the fingers. The command will be given externally using a keyboard.

Algorithm Design:

The programming of the microcontroller will be done using Arduino IDE. For different positions of the hand the motors will be trained accordingly. Through the embodied sensors we can mimic the human hand positions and then give the values to the microcontroller.

Performance Measure:

After the programming we will test the prosthetic hand. Our testing criteria will be depending upon three grasp types. i.e., Power grasp, pinch grasp and tripod grasp. If our hand doesn’t pass the above three tests. We will try to improve the hand actuation system or the design. We will make sure that the degree of freedom is as maximum as possible.

Benefits of the Project

Good Health and Well-Being for People:Modern surgery and intensive efforts to rehabilitate people who have lost limbs due to war, disease, or accident have resulted in significant advances in the science of prosthetics. So, in general, our invention is primarily concerned with humans.A person who is a victim of any accident, lost hand or limb can start a new life once again.

Using additive manufacturing, one can create a 3D arm in 34 hours, whereas current technology takes more than a week or a month in some cases.

Durable:Our project will be made out of soft robotic material, which enhances its durability The chances of its breakdown are low because it is made out of soft foldable  material, which not only increases its lifespan but the use soft materials gives an edge in power consumption as low mechanical and heavy parts increase its discharge cycle.

Dexterous Grasping:  Allows users to perform more flexible movements of the hand, similar to a natural human hand.

Appearance :The product has a fantastic aesthetic. Human hand inspired appealingly designed prosthetic hand.

Cost effective :The cost of the product is very low in comparison to the current prosthetic hand, so it is easily affordable to everyone. In the other case, suppose a prosthetic hand is currently designed for the child; as the child grows, we must redesign the prosthetic hand to fit the child's hand dimensions. So, if we consider the cost factor, it will be far more expensive than a 3D printed prosthetic hand.

Technical Details of Final Deliverable

Our systematic design is expected to achieve a lighter weight (easy to implement on the arm), three grasp types (with individual finger movement capability), power-grip, a lower finger flexion speed, a shorter grasping cycle (while retaining its original functionality), and a lower bill of material cost. We intend to perform an “Activities Measure for Upper-Limb Amputees benchmark” to assess our prototype's ability to perform grasping tasks required for daily living activities. And we hope to achieve satisfactory results with our proposed soft prosthetic hand, which can perform all of “the real-world grasping tasks of the benchmark tests” and has a high potential for improving the life quality of people with upper limb loss.

Final Deliverable of the Project

HW/SW integrated system

Core Industry

Medical

Other Industries

Manufacturing , Health

Core Technology

Robotics

Other Technologies

3D/4D Printing, Wearables and Implantables

Sustainable Development Goals

Good Health and Well-Being for People, Decent Work and Economic Growth, Reduced Inequality

Required Resources

If you need this project, please contact me on contact@adikhanofficial.com