PB&J: Peanut Butter and Joints for Damped Articulation

TL;DR

This paper introduces a bioinspired robotic hand with viscoelastic joints using accessible materials like peanut butter for damping, enabling secure grasping and dynamic responses similar to human joints, and provides an open-source platform for biomechanics research.

Contribution

The study presents a novel, low-cost robotic hand with viscoelastic joints using bioderived materials, demonstrating improved grasp stability and dynamic response capabilities.

Findings

Elastic joint elements are essential for secure grasping.

Peanut butter can effectively serve as a damping fluid.

The platform successfully catches a falling ball in real-time.

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.