Continuum Manipulator Actuated by Granular Jamming Media
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Solution Overview
Problem
Conventional robotic manipulators are fragile, expensive, and limited in flexibility due to rigid actuators, lack the ability to lock arbitrary segments, pose safety risks, and have limited workspaces, making them unsuitable for harsh environments and applications requiring dexterity and safety around living counterparts.
Innovation Solution
A manipulator design utilizing reversible jamming and unjamming of granular media within modules, coupled with off-board spooler motors and tension cables, allowing for tunable stiffness and complex configurations without traditional actuators, enabling passive conformation to environments and safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional robotic manipulators use rigid actuators distributed along their length, then precision and degrees of freedom are achieved, but the manipulators become fragile, expensive, and limited in flexibility
Solution Approach 1:
The patent extracts traditional rigid actuators from the manipulator structure and replaces them with a cable-driven system. Cables are routed through pulleys and connected to a single actuator located outside the manipulator body, eliminating the need for distributed actuators along the manipulator's length. This extraction enables continuous flexibility while maintaining precision through cable tension control.
Solution Approach 2:
The patent substitutes rigid mechanical actuators with a flexible cable-driven mechanism. Instead of using motors or hydraulic actuators embedded in rigid segments, the system uses flexible cables that can bend and conform to the manipulator's shape, replacing the rigid mechanical system with a flexible alternative that achieves the same actuation function.
2Reliability
If traditional actuators are placed along the length of the manipulator, then actuation capability is provided, but the actuators are subjected to harsh environments and add mass and moment load
Solution Approach 1:
The actuator is extracted from the manipulator body and relocated to an external position. The manipulator itself contains only passive cables and pulleys, while the active actuating component is positioned outside the manipulator structure. This extraction eliminates the mass and moment load of the actuator from the manipulator's moving parts while preserving full actuation capability through the cable system.
3Strength
If rigid links and joints are used in manipulators, then structural strength is provided, but pinch points are created that can injure living counterparts
Solution Approach 1:
The patent replaces rigid links and joints with a flexible cable-driven manipulator body that can be covered with soft, compliant materials. The flexible nature of the cable system allows the manipulator to conform to curved surfaces and avoid creating rigid pinch points. Soft covering materials can be applied over the flexible structure to provide tactile safety when interacting with living counterparts.
4Adaptability or versatility
If conventional manipulators are designed for dexterity, then complex configurations are achieved, but the workspace is limited and enclosures are required for safety
Solution Approach 1:
The flexible cable-driven structure allows the manipulator to be covered with soft, compliant materials that eliminate the need for rigid safety enclosures. The inherent flexibility of the system enables it to conform to environments and operate safely around living counterparts without requiring protective barriers, thereby expanding the operational workspace.
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 solution results in a robust, low-cost, highly articulated manipulator that can conform to various shapes, avoid pinch points, and operate in harsh environments with enhanced safety and flexibility, achieving a nearly spherical workspace without the need for on-board actuators.
Implementation Method 1
reversible jamming and unjamming of granular media within modules
Data Source
AI summary
A continuum style manipulator is actuated by jammable media within an envelope of a module, which is also actuated by a tensile element, such as a cable and spooler motor. Multiple modules may be reversibly added. Two or more tensile elements may also be used. Three or more actuated tensile elements can actuate three DOFs of each module, and the terminal module, as well as the entire manipulator. Jammable media may be granular, actuated by a pressure change. Coarsely ground coffee works well. Rather than a jammable media, tensile elements may alternatively be used with other phase change media, such as magnetorheological and electrorheological media. A high friction angle of the granular media is desirable, and has been achieved with a particle size dispersion including both small and relatively larger particles. Applications include endoscopes, proctoscopes, laparoscopic instruments, manufacturing and medical manipulators. Methods of actuating include unjamming all modules, positioning the manipulator with tensile elements or otherwise, jamming the base-most module, and then repositioning remaining, not-jammed modules, followed by jamming the base-most not-jammed module, and so on, until all modules are positioned and jammed.