Soft Robotic Gripper Positive Pressure Layer Jamming

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Solution Overview

Problem

Soft robotic grippers face limitations in payload capacity due to their compliance, and existing methods for varying stiffness, such as vacuum layer jamming, are restricted by atmospheric pressure, limiting their ability to apply sufficient compressive force for heavier loads.

Innovation Solution

The development of soft robotic grippers with a variable stiffness enabled by positive pressure layer jamming, where a jamming bag applies compressive force to layers within a rigid constraint frame, allowing higher pressure application and increased payload capacity, utilizing multi-material additive manufacturing to create a gripper with a thermoplastic elastomer actuator and polyester backbone.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If vacuum layer jamming is used to vary stiffness, then compliance and safety are improved, but payload capacity is limited due to atmospheric pressure constraints

Engineering Contradiction:

ImprovesafetyVSAvoidpayload capacity

Core Design Contradiction:

Object-affected harmful factorsVSForce

Solution Approach 1:

The patent inverts the conventional vacuum-based layer jamming approach by using positive pressure to compress the jamming layers. Instead of relying on atmospheric pressure to hold layers together (vacuum method), the invention actively pushes layers together using pressurized fluid, enabling higher compressive forces and thus higher payload capacity while maintaining the compliance benefits of soft robotics.

Inventive Principle:

Principle #13The other way round (Inversion)

2Adaptability or versatility

If vacuum compression is used for layer jamming, then variable stiffness is achieved, but the compressive force is limited by atmospheric pressure

Engineering Contradiction:

Improvevariable stiffnessVSAvoidcompressive force

Core Design Contradiction:

Adaptability or versatilityVSStress or pressure

Solution Approach 1:

The patent replaces vacuum compression with positive pressure compression. The jamming bag is inflated with pressurized fluid to actively push the jamming layers together, overcoming the atmospheric pressure limitation of vacuum-based methods. This enables higher compressive forces to be applied to the layers, achieving greater stiffness variation and higher payload capacity.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent uses pneumatic pressure (pressurized gas or fluid) to inflate the jamming bag, which then compresses the jamming layers. This pneumatic mechanism enables controlled application of high compressive forces to vary the stiffness of the soft robotic structure, overcoming the limitations of vacuum-based compression.

Inventive Principle:

Principle #29Pneumatics and hydraulics

3Object-affected harmful factors

If soft robotic grippers are designed with compliance, then safety around humans is improved, but payload weight capacity is reduced

Engineering Contradiction:

ImprovesafetyVSAvoidpayload weight capacity

Core Design Contradiction:

Object-affected harmful factorsVSForce

Solution Approach 1:

The patent implements dynamic stiffness control in soft robotic grippers by using pressurized fluid to inflate the jamming bag, which actively compresses the jamming layers to increase stiffness when high payload capacity is needed. When compliance is needed for safety, the pressure can be reduced or released, allowing the structure to remain soft and compliant. This dynamic adjustment resolves the contradiction between safety and payload capacity.

Inventive Principle:

Principle #15Dynamics

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

This approach achieves a 25-fold stiffness variation and 1.6× higher payload capacity compared to conventional vacuum-based layer jamming, with improved performance in grasping and manipulating objects, demonstrating enhanced payload handling capabilities.

Implementation Method 1

The jamming bag disposed at least partially within the rigid constraint frame and configured to apply a compressive force to the jamming layers when a positive pressure is generated within the jamming bag

Methodology Applied

Scientific EffectPositive pressure layer jamming: Compression

Implementation Method 2

Jamming refers to a class of variable stiffness technologies which rely on compression of a substrate in the joint to produce a locking effect through friction

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 3

Soft robots are typically fabricated from elastomeric or flexible materials with a monolithic construction

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS20230286177A1Soft robotic gripper with a variable stiffness enabled by positive pressure layer jamming

Publication Date: 2023.09.14 OHIO STATE INNOVATION FOUND

AI summary

A finger for a robotic gripper may include a flexible actuator, a flexible backbone, a rigid constraint frame, a plurality of jamming layers, and a jamming bag. The flexible actuator may have a proximal end, a distal end disposed opposite the proximal end, a first side, and a second side disposed opposite the first side. The flexible backbone may be coupled to the flexible actuator and disposed along the first side of the flexible actuator. The rigid constraint frame may be coupled to the flexible actuator and disposed along the second side of the flexible actuator. The jamming layers may be coupled to the flexible actuator and disposed at least partially within the rigid constraint frame. The jamming bag disposed at least partially within the rigid constraint frame and configured to apply a compressive force to the jamming layers when a positive pressure is generated within the jamming bag.