Helical Soft Robotic Gripper With Variable Stiffness for High Load Grasping
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Solution Overview
Problem
Existing soft robotic grippers face limitations in conformability for irregular shapes and load capacity, with continuum, helical grippers offering flexibility but low load capacity, and finger-based designs struggling with large objects and confined spaces.
Innovation Solution
A soft hydraulic filament artificial muscle (HFAM) with a continuum, helical configuration and integrated variable stiffness structure, combined with a stretchable liquid-metal-based sensor, enabling high load capacity and sensitivity for grasping various shapes and sizes, and retrieving objects from confined spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If continuum, helical gripper configuration is used, then flexibility and conformability are improved, but load capacity deteriorates
Solution Approach 1:
The gripper combines soft compliant materials (silicone elastomer) with rigid reinforcement elements (shape memory polymer ribs and metal springs) to create a composite structure that achieves both flexibility and high load capacity simultaneously
Solution Approach 2:
The shape memory polymer ribs provide variable stiffness through phase transition, allowing the gripper to dynamically adjust between soft conformable state for irregular objects and stiff strong state for load-bearing operations
2Force
If finger-based gripper design is used, then load capacity is improved, but adaptability to irregular shapes and confined spaces deteriorates
Solution Approach 1:
The gripper uses a continuous helical shell structure made of soft silicone elastomer that can conform to irregular object shapes while maintaining structural integrity and load capacity through the integrated reinforcement elements
Solution Approach 2:
The helical gripper is divided into multiple segments with independent shape memory polymer ribs that can deform and adjust locally to match irregular object geometries while the overall structure maintains strength
3Adaptability or versatility
If soft compliant materials are used, then flexibility and human-friendly interaction are improved, but strength and durability deteriorate
Solution Approach 1:
The invention creates a composite material system combining soft silicone elastomer with rigid shape memory polymer ribs and metal spring reinforcements, achieving both flexibility and high strength through material composition
Solution Approach 2:
Different parts of the gripper have different material properties - the outer shell remains soft and compliant for safety and conformability, while the integrated ribs and springs provide localized rigid reinforcement for strength and durability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The HFAM-based gripper achieves high load capacity and sensitivity, allowing it to grasp objects up to 220 times its own mass and provide enhanced sensory feedback, suitable for diverse applications including fragile objects and confined environments.
Implementation Method 1
The liquid metal alloy is drop-casted or inkjet-printed onto a substrate and undergoes phase transition to form conductive microtubules
Implementation Method 2
configured to extend and contract in response to differentiation in hydraulic pressure
Data Source
AI summary
An elongated actuator including: an elongated inner tube for carrying a pressurized actuation fluid; a helical coil wrapped around the elongated inner tube; wherein the actuator undergoes actuation by means of pressure fluctuations in the elongated inner tube.