Mimicking the human arm

Abstract

This project developed a functional robotic elbow prototype to support research in movement rehabilitation. Our goal was to create an affordable, open platform that could simulate both natural elbow motion and impaired movement patterns like spasticity while meeting basic safety requirements for rehabilitation applications.

The prototype combines 3D printed components with off-the-shelf mechanical parts, including a bicycle disc brake system for adjustable resistance. We used PLA and PETG thermoplastics for most structural elements, with aluminium for high-stress components. The system is controlled by an Arduino-based circuit that manages a stepper motor and braking mechanism, allowing precise movement regulation.

Key challenges we addressed include designing a compact joint mechanism, integrating the brake system in a limited space and solving voltage compatibility issues between components. The final prototype can generate a sufficient breaking torque to simulate resistance patterns seen in neurological conditions.

Beyond the technical implementation, we considered critical societal aspects like cost barriers in rehabilitation technology and the ethical implications of robotic systems in healthcare. The total project cost remained under 5,000 SEK, demonstrating that functional rehabilitation prototypes can be developed with modest budgets.

This work provides a foundation for future development in accessible rehabilitation technology. The open design allows for improvements like additional joints or more sophisticated control systems, while the modular approach enables adaptation for different research or clinical needs.