A team of UCLA engineers has developed a new class of tunable dynamic material that mimics the inner workings of push puppet toys, with potential applications in soft robotics, reconfigurable architectures, and space engineering. The material is based on the cord tension principle found in push puppets and can be tuned to adjust its stiffness by changing the tension in the cords. By using motor-driven or self-actuating cords threaded through interlocking cone-tipped beads, the material can transition from a limp state to a stiff structure when activated.
The lightweight metamaterial demonstrated in the study published in Materials Horizons offers versatile qualities that could make it useful for soft robotics and other reconfigurable structures. The material can collapse and stiffen repeatedly, making it suitable for designs that require frequent movements. The precision geometry of the nesting cones and the friction between them allow for incremental changes in stiffness while maintaining strength. The material also offers ease of transportation and storage when in its undeployed state.
The researchers believe that the new metamaterial has great potential for incorporation into robotics, reconfigurable structures, and space engineering. It could enable self-deployable soft robots to calibrate their stiffness for different terrains, optimize movement, and perform tasks like lifting, pushing, or pulling objects. The contracting-cord metamaterial concept opens up possibilities for building mechanical intelligence into robots and other devices, offering programmable dampening capabilities and the ability to adapt to changing environments.
The potential applications of the material include self-assembling shelters with collapsible scaffolding and compact shock absorbers with programmable dampening capabilities for vehicles in rough environments. By altering the size and shape of the beads and how they are connected, the capabilities of the material can be tailored and customized for specific needs. The research focused on exploring the mechanical properties of contracting cords and identifying ideal shapes for bead alignment, self-assembly, and the ability to be tuned to hold their overall framework.
The study was funded by the Office of Naval Research, the Defense Advanced Research Projects Agency, and the Air Force Office of Scientific Research. Computational and storage support for the research was provided by the UCLA Office of Advanced Research Computing. The senior authors on the paper are Ankur Mehta, an associate professor of electrical and computer engineering, and Jonathan Hopkins, a professor of mechanical and aerospace engineering. The research team also included graduate students from UCLA and Georgia Institute of Technology who contributed to the project while affiliated with Hopkins’ lab.
