Preface

This was a submission to Columbia University's 7th annual Senior Design Expo; however, because of 2019 SARS-CoV-2 , projects were finished remotely and much of the hardware reamains in the prototype stage of design.

Executive Summary

The Power Arm is a cabel-actuated robotic exoskeleton arm design which uses bowden cables to transmit power from back-mounted high torque stepper motors that are regulated by a microcontroller and ratchet-pawl locking system. The device is remote controlled using input from a mobile GUI (or wireless remote), visulalizing in real-time the joint angles, power output, movement speed, and other parameters being calculated.

My Contributions

Desktop GUI

I made a GUI to run on the Rasberry Pi controlling the Power Arm. It's scripted with C# in Unity 3D. It's designed to visulalize in real-time:

• joint angles
• power output
• movement speed

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Analog Remote

I designed and prototyped a wireless remote for single-handed operation. A touch sensor on the back acts as a safty switch and an analog joystick acts as a throttle to move the end effector in a corresponding planar direction. I made a mockup using Solidworks and wired the components to a protoboard.

Features:

• digital signal filtering
• wireless transmission
• status light
• battery monitoring
• rechargable via micro USB-B

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Demo Video

With my teammates and I as the co-stars and co-writters of this modest production, I was the video editor for our pitch video. I used Adobe Premiere Pro to immitate an old school infomercial - we wanted to give the project a little levity given the unforseen circumstances in which it ended.

Objective

With a projected value of $5.2 billion by the year 2025, the market for wearable robotic exoskeletons is grow-ing at an unprecedented pace. Competitors in this sector have been making waves with wearables that provide rehabilitative support or supplemental aid for a select worker demographic. Yet, jobs requiring strenuous manual labor in every industry from automobile manufactures to courier and shipping services stand to benefit from more worker friendly assistive tools because chronic back and joint pain can severely limit productivity and quality of life.

Thus, this project sought to aid individuals with limited strength/mobility and prevent long term fatigue for such workers with a novel design that balances:

• Cost
• Portability
• Ergonomics
• Functionality

Power Arm is unique its potential to provide powerful lifting capabilities at an unmatched price point, yeilding it a reasonable option for a larger array of industries.

Parameters, Constraints, and Safety Considerations

Whether it's for lifting heavy objects or getting assistive power when performing repeated tasks to minimize fatigue, augmentative strength capabilities are useful for everyone. Such a device that can achieve such wide adoption will be distinguished by its performance in three categories:

Functionality:

power output comparable to or excelling beyond what is currently available

Availability:

abiility to fit a wide variety of individuals and upper extremities of differing lengths and sizes

Ergonomics:

ease of use, comfortability, and portability that accomodates varied and extended uses

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Our design is limited by the financial and time recourses available to our team, namely:

• Budget: $1000 + Sponsorships
• Time: Seven month deadline

Additionally, there are a number of precautions that had to be taken into account for safe use:

Saftey Concern	Design Consideration
Over Extension or Sudden Actuation	Mechanical stops limiting joint angles Electrical emergency stop Motor acceleration sensors
Unintentional Actuation and Sensor Noise	Digital signal filtering Simple to use remote control Safety triggers built into remote control
Exposure to High-Voltage and Large Current	Applicable Codes and Standards: IEEE P360 Wearable Consumer Electronic Devices UL Wearable Devices Safety Compliance