PB&J: Peanut Butter and Joints for Damped Articulation
Journal:
arXiv
Published Date:
May 30, 2025
Abstract
Many bioinspired robots mimic the rigid articulated joint structure of the
human hand for grasping tasks, but experience high-frequency mechanical
perturbations that can destabilize the system and negatively affect precision
without a high-frequency controller. Despite having bandwidth-limited
controllers that experience time delays between sensing and actuation,
biological systems can respond successfully to and mitigate these
high-frequency perturbations. Human joints include damping and stiffness that
many rigid articulated bioinspired hand robots lack. To enable researchers to
explore the effects of joint viscoelasticity in joint control, we developed a
human-hand-inspired grasping robot with viscoelastic structures that utilizes
accessible and bioderived materials to reduce the economic and environmental
impact of prototyping novel robotic systems. We demonstrate that an elastic
element at the finger joints is necessary to achieve concurrent flexion, which
enables secure grasping of spherical objects. To significantly damp the
manufactured finger joints, we modeled, manufactured, and characterized rotary
dampers using peanut butter as an organic analog joint working fluid. Finally,
we demonstrated that a real-time position-based controller could be used to
successfully catch a lightweight falling ball. We developed this open-source,
low-cost grasping platform that abstracts the morphological and mechanical
properties of the human hand to enable researchers to explore questions about
biomechanics in roboto that would otherwise be difficult to test in simulation
or modeling.
