Worcester Polytechnic Institute (WPI) researchers are developing an innovative soft robotic arm that could significantly enhance independence for wheelchair users. The lightweight, flexible arm—inspired by origami folding techniques—aims to help users safely grasp, lift, and carry objects that would otherwise be beyond their reach.
The four-year project, funded by a $1,314,792 grant from the National Science Foundation (NSF), focuses on creating a comprehensive framework for designing, modelling, and controlling soft continuum robotic arms. This emerging robotic system class offers greater flexibility than conventional rigid robot arms.
Soft continuum robotic arms expand, contract, and bend along their entire length, similar to a coiled spring, allowing them to move in multiple directions and navigate obstacles. While this flexibility makes them promising for complex human environments, soft robotic systems typically have significant limitations compared to their rigid counterparts.
“Soft robotic arms tend to be weaker, less stable, and less precise than traditional robot arms made from rigid materials,” explains Cagdas Onal, principal investigator and associate professor in WPI’s Department of Robotics Engineering. “Our research aims to overcome these inherent weaknesses.”
To address these limitations, the research team—which includes Onal along with robotics engineering professors Berk Calli and Loris Fichera—is developing origami-inspired designs and novel fabrication methods using lightweight plastics, 3D-printed components, and commercially available sensors and cables.
The project’s core innovation lies in its structural approach. By folding flat sheets of clear plastic into springy, tube-like structures, the researchers are creating modules that combine lightweight properties with strength, stiffness, and resistance to twisting—a critical combination for practical assistive robotics.
“You would need a very large, rigid robot to reach the high shelves of a cabinet, for example, and installing such robots next to a user doesn’t make sense,” explains Calli. “Soft robots could expand to reach objects and shrink to a compact size when not in use, and they would be safer for users than rigid robots.”
The WPI team is simultaneously developing specialised algorithms that can run on microcontroller platforms to direct the robotic arm’s motion and responses. These algorithms are critical for ensuring precise control despite the materials’ inherent flexibility.
Deep Dive: Engineering Principles in Soft Robotics
The WPI team’s approach to soft robotics integrates several engineering disciplines:
Materials Engineering: The researchers utilise specialised plastics that maintain flexibility while providing structural integrity. The folding patterns create mechanical properties that distribute force throughout the structure while minimising total weight.
Control Systems: Unlike rigid robotics, where movement is predictable along fixed joints, soft robotics requires complex mathematical modelling for continuous deformation along the entire structure. The team is developing specialised control algorithms that can:
- Compensate for non-linear deformation
- Account for variable stiffness throughout the arm
- Maintain positional accuracy despite the inherent flexibility
Sensor Integration: The modules incorporate distributed sensor networks that provide real-time feedback on the arm’s shape, position, and applied forces. This sensory data feeds into the control algorithms to ensure precise movement and object manipulation.
Fabrication Techniques: The manufacturing process involves precisely folding and bonding plastic sheets to create modules with specific mechanical properties. 3D-printed components provide structural support at key junction points while maintaining the system’s overall flexibility.
This technology’s immediate application is helping wheelchair users perform daily tasks more independently. One specific goal outlined by the researchers is to develop a flexible, extendable robotic arm with off-the-shelf grippers capable of picking up and carrying a cup of water without spilling—a task that combines the need for reach, stability, and precision.
“The basic scientific discoveries we are making in this research address real-world challenges for people who use wheelchairs and need devices that will help them grab out-of-reach objects,” says Onal. “A new class of lightweight, safe robotic arms based on the breakthroughs we’re making would give those individuals more independence in their daily activities.”
The project builds on Onal’s research into user-friendly soft robotic systems designed for tasks that rigid robots cannot perform. Calli contributes expertise in object manipulation technologies, particularly his work with robots in recycling centres. Fichera, whose research includes surgical robot development, brings additional specialised knowledge to the team.
The team’s modular approach allows customisation based on specific user needs and applications. Individual segments can be connected and controlled independently, offering scalability in both the arm’s length and operational complexity.
This modular design also enables the integration of different end effectors or grippers, depending on the task. For example, a soft gripper might be appropriate for handling delicate objects, while a more rigid gripper could be used for heavier items.
The researchers utilise commercially available components wherever possible to keep costs manageable and accelerate potential adoption once the technology is ready for implementation.
While the current research focuses specifically on assistive technology for wheelchair users, the engineering principles developed have broader applications in healthcare and industrial automation.
“It’s exciting to work with WPI colleagues and students on a project that is pushing the boundaries of this technology,” says Onal. “More importantly, this research offers an opportunity to directly impact people in a positive way by enabling them to lift, move, and carry objects that they previously might not have been able to reach from a wheelchair.”
If the project succeeds, the researchers hope to develop a commercially viable product that can be attached to standard wheelchairs. This would provide users with enhanced reach capabilities while maintaining safety and ease of use. The control system could be integrated with various user interfaces, including voice commands or simplified button controls, making it accessible to people with different levels of mobility.
The fundamental research into soft continuum robotics could also lead to advances in medical devices, search and rescue equipment, and industrial applications where flexibility and safety are paramount concerns.
As the team continues their work over the four-year grant period, they plan to conduct user testing to refine the design based on practical feedback from the intended users. This will ensure that the final product truly meets the needs of wheelchair users seeking greater independence in their daily lives.
TLDR:
• Worcester Polytechnic Institute researchers are developing an origami-inspired soft robotic arm to help wheelchair users grasp out-of-reach objects • The technology uses folded plastic sheets to create lightweight, flexible but strong tube-like structures • Special algorithms control the arm’s movement with precision despite its flexible nature • The project aims to create a system that can perform tasks like carrying a cup of water without spilling • The $1.3 million NSF-funded research could lead to greater independence for wheelchair users
