ExoKit: A Toolkit for Rapid Prototyping of Interactions for Arm-based Exoskeletons

Research Background and Problem

• Identified Problem: Wearable exoskeletons for the human body hold great potential in the field of human-robot interaction, as they can assist, enhance, or restrict physical movements. However, current research on exoskeletons in human-computer interaction (HCI) remains limited, primarily due to the lack of affordable and customizable rapid prototyping tools. Such tools need to reduce development complexity and enable designers to explore exoskeleton interaction behaviors during the early design stages.
• Significance: Exoskeleton technology, combining human motion and robotics, can revolutionize interaction methods and find applications in rehabilitation, enhancing athletic performance, virtual reality, and more. However, due to the high cost and difficulty of customization in existing commercial exoskeleton devices, most beginners cannot afford or develop functional interaction prototypes.
• Research Motivation and Related Work: The authors analyzed the shortcomings of current exoskeleton research and referred to relevant literature in the fields of upper-limb biomechanics, robotics programming, and toolkit design. They found that existing open educational exoskeleton tools (such as EduExo) provide limited support for beginners, as users still need to handle complex low-level motion control. Therefore, there is an urgent need to develop tools that enhance accessibility and flexibility while reducing development difficulty.

Solution

• Proposed Approach: ExoKit is an open-source toolkit designed for rapid prototyping of low-fidelity functional exoskeletons, targeting beginners with basic electronics and programming skills. The toolkit is designed to support early exploration in the field of upper-limb exoskeleton interaction.
  • Hardware Modules: Provides modular components, including sensing and actuation modules for shoulder and elbow joints, which can be flexibly adjusted and reconfigured according to user needs.
  • Software Library: Offers abstracted functionalities, such as motion enhancement strategies, accessible through command-line interfaces, graphical user interfaces, Processing libraries, or Arduino firmware.
• Innovations:
  • Modular design enables rapid iteration of hardware and interaction behaviors.
  • High-level abstract functionalities (e.g., motion amplification, restriction, and style adjustment) reduce development complexity, eliminating the need for users to delve into low-level motion control.
  • Cross-platform support caters to users with varying levels of expertise, offering command-line, GUI, and text-based programming interfaces.
• Implementation Steps:
  1. Hardware Assembly: Use standard 3D printing equipment to manufacture hardware components and pair them with common electronic components (e.g., Arduino and Dynamixel motors).
  2. Function Configuration: Calibrate the hardware using the software library, define initial angles, and design functional behaviors.
  3. Function Implementation: Based on user needs, select basic functionalities or enhancement strategies and control the hardware via software to achieve real-time interaction prototypes.

Research Outcomes

• Specific Results:
  • The authors developed a complete hardware and software solution that supports the prototyping of upper-limb exoskeletons with up to six degrees of freedom.
  • ExoKit's hardware design allows for quick adjustments to joint and link lengths to accommodate users of different body sizes and includes multiple safety measures.
  • The software provides low-threshold functional interfaces for developing complex interaction behaviors.
• Advantages:
  • Compared to existing exoskeleton solutions, ExoKit is more cost-effective, flexible, and optimized for beginners. For example, it is lighter and easier to assemble than industrial exoskeletons.
  • Its modular design supports applications in various scenarios, including rehabilitation training, haptic feedback in virtual reality, and collaborative interactive games.
• Experimental and Evaluation Results:
  • Two user studies demonstrated that participants could use ExoKit to create functional application prototypes, such as motion training assistants, sound synthesizers, and haptic interactions in virtual reality.
  • The studies showed that ExoKit supports beginners in exploring interactions and lowers technical barriers in prototype design.
• Limitations and Future Directions:
  • Limitations: Currently, supported body parts are limited to the upper limbs, excluding full-body interactions; the strength of 3D-printed ABS hardware is limited, making it unsuitable for heavy-load applications; the motors used remain relatively expensive.
  • Future Directions:
    • Expand functionality to support full-body interactions, such as leg exoskeletons.
    • Integrate more cost-effective actuation modules to reach a broader user base.
    • Provide visual programming interfaces and interaction behavior simulation tools to further reduce programming difficulty.
    • Optimize module connection designs to enable tool-free rapid configuration mechanisms.

Conclusion

ExoKit provides an open-source toolkit that spans hardware and software, making early-stage exoskeleton interaction design more affordable and accessible. This work opens new possibilities for creative exploration while highlighting the importance of toolkit design in lowering the barriers to innovation.