MELEGROS: Monolithic Elephant-inspired Gripper with Optical Sensors

2025-09-24

AI Summary

Soft robotic grippers face significant challenges in monolithically integrating structural, actuation, and sensing functionalities due to mechanical incompatibility and assembly complexity. Method: Inspired by the morphology of the African elephant trunk tip, this work proposes a novel paradigm that unifies fully embedded optical sensing with continuous lattice-based pneumatic architecture. We fabricate MELEGROS—a monolithic, trunk-inspired soft gripper—via single-step, multi-material-compatible 3D printing using a single elastomeric resin, concurrently embedding six optical waveguide sensors and five pneumatic chambers within a graded lattice structure. Simulation-guided optimization required only four iterative cycles. Contribution/Results: The resulting gripper (132 g) achieves a load capacity exceeding 264 g and demonstrates dexterous manipulation—including pinch, scoop, extension, and delicate grasping (e.g., grapes)—enabled by decoupled tactile and proprioceptive feedback, multi-DOF deformation, and multimodal perception.

Technology Category

• Intelligent Robots: Multimodal Perception & Sensor Fusion
• Humans and AI: Brain-Sensing and Analysis
• Search and Optimization: Mixed Discrete/Continuous Search

Application Category

• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Systems and Infrastructure for Web, Mobile and WoT: Applied ML and AI for Web-based mobile applications
• Search and Retrieval-Augmented AI: Agentic search

Abstract

The elephant trunk exemplifies a natural gripper where structure, actuation, and sensing are seamlessly integrated. Inspired by the distal morphology of the African elephant trunk, we present MELEGROS, a Monolithic ELEphant-inspired GRipper with Optical Sensors, emphasizing sensing as an intrinsic, co-fabricated capability. Unlike multi-material or tendon-based approaches, MELEGROS directly integrates six optical waveguide sensors and five pneumatic chambers into a pneumatically actuated lattice structure (12.5 mm cell size) using a single soft resin and one continuous 3D print. This eliminates mechanical mismatches between sensors, actuators, and body, reducing model uncertainty and enabling simulation-guided sensor design and placement. Only four iterations were required to achieve the final prototype, which features a continuous structure capable of elongation, compression, and bending while decoupling tactile and proprioceptive signals. MELEGROS (132 g) lifts more than twice its weight, performs bioinspired actions such as pinching, scooping, and reaching, and delicately grasps fragile items like grapes. The integrated optical sensors provide distinct responses to touch, bending, and chamber deformation, enabling multifunctional perception. MELEGROS demonstrates a new paradigm for soft robotics where fully embedded sensing and continuous structures inherently support versatile, bioinspired manipulation.

Problem

• Designing a soft robotic gripper with seamless sensor-actuator integration
• Eliminating mechanical mismatches in soft robots to reduce model uncertainty
• Achieving multifunctional perception for delicate and bioinspired manipulation tasks

Innovation

• Monolithic soft resin structure with integrated optical sensors
• Single continuous 3D printing process for pneumatic chambers
• Decoupled tactile and proprioceptive sensing capabilities