Wearable Soft Robot for Upper limb Assistance and Rehabilitation

Hand injuries for example fractures etc. can cause the muscles to weaken which results in low mobility of the affected  part. Patients with the concerned problem are required to carry out intensive and exhaustive hand therapies. Different methods have been used to improve the agility of the upp

Project Title

Wearable Soft Robot for Upper limb Assistance and Rehabilitation

Project Area of Specialization

Robotics

Project Summary

Hand injuries for example fractures etc. can cause the muscles to weaken which results in low mobility of the affected  part. Patients with the concerned problem are required to carry out intensive and exhaustive hand therapies. Different methods have been used to improve the agility of the upper limb. Rehabilitative exercises under the supervision of physician improve hand motion. This method is labor arduous, slow, and costly and demands experienced therapist. Therapy techniques using robotic assistance have been developed over the years. Exoskeleton robotic systems with multi-degrees of freedom have been introduced. Most of the robotic systems have bulky bodies with rigid links connected by joints. These rehabilitation systems are very costly and can cause injuries to the patients due to their stiff bodies. The bulky weight makes them difficult to be portable. To overcome these limitations, soft robot rehabilitation systems are developed. Soft robots have flexible bodies, are lighter, easy to assemble and comparatively cheaper than other rehabilitation systems. Due to flexible bodies of soft robots, patient’s safety is guaranteed.  This project presents the design of portable soft robotic glove which would assist patients to perform rehabilitation exercises using mobile phone app. The glove would also assist patients who have grasping problems to carry daily life activities i.e. picking and placing the objects. The robotic glove consists of actuators made up of soft flexible material which provides required flexion and extension when pressurized with air. The actuators provide enough force to grasp objects. Soft actuators are fiber reinforced to achieve required bending. An electronic control board is designed thorough which actuators are operated. A customized app is designed, through which patient can select pick and place option or any hand rehabilitative exercise and the glove would assist him performing exercise. This soft robotic glove is user friendly, safe, light in weight and economical.

Project Objectives

The main objectives of our projects are listed below:

• Designing of a soft robotic glove which would assist hand impaired patients in accomplishing daily life activities i.e. picking and placing of the objects.

• Design a mobile app for performing rehabilitation exercises based on different fingers movement patterns.

Project Implementation Method

Based on literature, a viable approach for actuator are the Fiber Reinforced (FR) actuators. Soft Lithography method is proposed for the fabrication of silicon based fiber reinforced actuator. Soft Lithography method has the capability to bear high pressure and transfer it properly due to its shape. The proposed method involves casting manually, hence expensive and specialized equipment for casting is not required. Fabrication of actuator using lithography method involves the following steps:   

• Mold making

• Casting and Actuator release from the mold

Mold Designing:

Molds for the actuators are designed in fusion 360 and material that is used for 3D printing of molds is Polyactic Acid (PLA).

Casting:

Two parts silicon elastomer is used for casting of actuator body. The proposed method for casting of molds is as follows:

• Mixed two portions of silicon elastomer and pour into the main mold.

• Fixed steel rod in main mold and add more silicone.

• Cover mold with the top mold and place it in a vacuum chamber for degassing.

• Cured the silicone body at room temperature after the degassing process.

• Remove silicone body from a mold after it is cured.

• Wrap fish thread around the actuator body in a double helical manner to limit radial expansion.

• Apply another layer of silicone to fix the fiber in its place.

• Add strain limiting layer at the bottom that helps the actuator in bending.

• Remove the rod and close both ends.

• Close one end of actuator with a RTV silicone cap and install vented screw on the other end through which air pressure will be applied on the actuator.

Actuator Control Using Mobile App:

Mobile app is designed through which a patient selects the option and glove will assist the patient to do the picking, placing and rehabilitation exercises even in the absence of physician.  The actuators of soft robot glove will inflate or deflate according to selected pattern.

Electronic Circuit Board:

Electronic Circuit board is used to control inflation and deflation of actuator. Open source microcontroller i.e Arduino, is used which would instruct the pump to provide air to the actuators. The motor driver module l298N is used to control air pump and to convert the low current into high current of 2A. Mobile app is interfaced with Arduino using Bluetooth module. According to the patient command on app, microcontroller will send the signal to the respective solenoid valve for opening and closing and the actuator will inflate or deflate. The fast switching of solenoid valve is done through IRF540 Mosfets. A pressure sensor is used to measure the air pressure in actuators. The electromyography sensor (EMG) is used for evaluating the performance

Benefits of the Project

The designed soft robotic glove will have following benefits:

• It will be highly beneficial to our society as most of the patients do not have access to advanced physical rehabilitation centers.

• It will provide assistance to the patient with hand pathologies in doing daily life activities

• As the designed glove is portable, user friendly, safe, light in weight and economically viable, eliminating the hectic hospital visits for exercise as patients will be able to do exercise without supervision of physiotherapist using app.

• It will provide a chance for the hand impaired patient to regain their ability to play their healthy part in society which otherwise is restricted due to physical disability.

• As soft robotics is new field, this project will encourage other fellow student to research further in this field.

Technical Details of Final Deliverable

A glove is designed on which actuators are mounted.  The hand assistive glove is controlled by soft silicon based actuators. Design and fabrication of actuators involve following steps

• • CAD drawing for the semi -circular shaped mold  is done using fusion 360

  • 3D printing of mold

  • Actuator making

  • Addition of fiber structure

The actuators are controlled by mobile app for carrying out daily life activities and exercise. LabView interface and mobile is developed for users to control the movement of actuators. For app control, arduino is coded using arduino IDE. App is developed on MIT App Inventor. labView interface is developed on labView 2017. The control board will be enclosed in a box to make comfortable for patient to carry it around. The control board require 9V DC voltage and 2A DC current for the proper working of all components.

Final Deliverable of the Project

HW/SW integrated system

Type of Industry

Medical , Manufacturing , Health

Technologies

3D/4D Printing, Robotics, Wearables and Implantables

Sustainable Development Goals

Good Health and Well-Being for People, Affordable and Clean Energy

Required Resources

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