Overview and Objectives

The primary objective of this project was to develop an affordable, lightweight, and functional assistive exomuscle that enhances index finger and thumb movement for users with limited dexterity. The engineering design process ensured a systematic problem-solving approach and guided the development of an effective and functional solution. The project followed five key phases:

• Defining the Problem: Addressed dexterity limitations for individuals with muscle weakness or mobility impairments, aiming to create an affordable alternative to existing exoskeletons.

• Generating Concepts: Explored actuator-based, gear-driven, and string-based exoskeleton models while conducting functional decomposition to establish key engineering metrics.

• Selecting the Final Design: Chose a string-based exomuscle for its lightweight structure, user comfort, and cost efficiency, aligning with industry safety standards (ISO 13482:2014).

• Prototyping and Fabrication: Developed 3D-printed TPU and PLA components for the hand brace, finger caps, and gauntlet while integrating MG996R servos for actuation.

• Testing and Evaluation: Conducted grip strength and usability tests to measure grasp success, placement accuracy, and user effort, refining wearability, response time, and mechanical efficiency based on feedback.

By following this structured methodology, the team successfully transitioned from conceptualization to a functional prototype, validating design assumptions through real-world testing and user feedback.

Project Accomplishments

The final prototype of flEXO incorporated 3D-printed components for flexibility and durability while utilizing servo motors and a microcontroller for precise motion control. The design allowed users to achieve finger flexion and extension through tensioned strings that mimicked the mechanical actions of the flexor and extensor muscles.

Key Achievements:

• Compliance with Engineering Standards: Designed according to ISO 13482:2014 and IEC 60601-1 to ensure mechanical and electrical safety.

• Successful Prototyping and Fabrication: Created a lightweight, wearable assistive device that allows users to perform pincer-grasp tasks.

• Iterative Design Refinements: Addressed comfort concerns, improved user satisfaction, and validated technical performance through multiple iterations.

• User Testing and Evaluation: Conducted functional tests that confirmed grasping capability, usability, and system reliability.

The flEXO prototype successfully met its objective of providing pincer-grasp assistance, demonstrating the feasibility of a user-centric exomuscle that can be worn, adjusted, and operated with ease.

My Role as Fabrication/Manufacturing Lead

As Fabrication Lead, I was responsible for transforming design concepts into reliable hardware. I collaborated closely with other team members to ensure seamless integration of mechanical, electrical, and software elements. My primary responsibilities included:

1. Bill of Materials (BOM) Management

   • Compiled a detailed BOM covering motors, controllers, sensors, and raw materials.

   • Balanced budgetary constraints, lead times, and technical requirements to secure all necessary components.

   • Verified that servo torque ratings, fishing line tensile strengths, and plastic materials met engineering targets for durability and performance.

2. Prototyping and Manufacturing

   • Material Selection and Procurement: Researched and sourced materials to balance cost, durability, and manufacturability.

   • 3D Printing: Selected PLA for structural rigidity and TPU for flexibility to optimize comfort and strength.

   • Assembly Process: Developed an efficient workflow for integrating components while maintaining structural integrity and functionality.

3. Embedded Systems and Hardware Integration

   • Microcontroller Programming: Developed code to process EMG sensor data and control servo motors, achieving precise finger movement.

   • Circuit Design and Prototyping: Simulated and tested electrical circuits to ensure robust signal processing.

   • Hardware Optimization: Selected high torque servos and efficient power components to maximize performance and conserve energy.

4. Testing and Performance Validation

   • Functional Testing: Conducted grip strength, flexion control, and weight capacity tests to evaluate the device’s effectiveness.

   • User Trials: Wore the exomuscle to identify mechanical weaknesses and refine the design for better fit and stability.

   • Iterative Redesign: Adjusted string tensioning pathways and servo alignment to enhance response time and grip consistency.

Reflection and Future Work

The flEXO project stands as a strong demonstration of the engineering design process, transitioning from problem definition to delivering a functional prototype. The final report outlines a roadmap for future improvements, including:

• Reducing Weight: The 586g weight slightly exceeded the 500g target, making the device somewhat bulky.

• Enhancing Control Mechanisms: Further optimization of EMG signal processing is needed to reduce noise and improve response time.

• Refining User Comfort: Smoother gauntlet edges, improved wire management, and quieter servos would enhance the user experience.

• Expanding User Testing: Conducting trials with a diverse range of users with different hand sizes and impairment levels to refine ergonomics and functionality.

The project provided invaluable experience in hands-on engineering, problem-solving, and cross-disciplinary collaboration. As Fabrication Lead, I played a crucial role in ensuring that design concepts evolved into reliable, testable hardware. The flEXO project showcases my ability to integrate mechanical, electrical, and software engineering principles to solve real-world challenges in assistive technology, reinforcing my expertise in mechatronics, robotics, and embedded systems.