Variable-Friction Collapsible Protrusions for Robotic Grasp Slippage
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Solution Overview
Problem
Conventional robotic end effectors have fixed coefficients of friction, limiting their grasp types and manipulation capabilities, particularly for objects requiring controlled slippage or property inference.
Innovation Solution
Collapsible protrusions with a variable coefficient of friction, extending from a base, allow for a non-collapsed state to a collapsed state based on sensor detection and applied force, enabling controlled slippage and sensing of objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed coefficient of friction is used in conventional robotic end effectors, then stable grasping is achieved, but the range of grasp types and manipulation capabilities is restricted
Solution Approach 1:
The end effector incorporates regions with different coefficients of friction on its surface - high friction regions for stable grasping and low friction regions for controlled slippage. This spatial variation in friction properties allows the same end effector to perform multiple grasp types and manipulation tasks by selectively engaging different friction zones.
Solution Approach 2:
The end effector can dynamically transition between high friction and low friction states, or between different friction regions, during manipulation tasks. This dynamic adjustment of friction characteristics enables adaptive control of object slippage and facilitates diverse manipulation capabilities while maintaining stability when needed.
2Reliability
If a high coefficient of friction is used to ensure stable grasping, then object manipulation stability is improved, but controlled slippage becomes difficult to achieve
Solution Approach 1:
The end effector surface is divided into distinct friction zones - high friction regions that provide stable grasping and low friction regions that enable controlled slippage. By positioning and activating specific zones, the system achieves both stability and controlled slippage as needed for different manipulation tasks.
Solution Approach 2:
The end effector acts as an intermediary between the robot gripper and the object, providing a friction interface that can be selectively modulated. The variable friction surface mediates the interaction by allowing stable contact in some regions while permitting controlled slippage in others, facilitating both grasp stability and manipulation flexibility.
3Ease of operation
If a low coefficient of friction is used to allow object slippage, then repositioning capability is improved, but grasping stability deteriorates
Solution Approach 1:
The end effector incorporates spatially distributed friction regions where low friction zones enable object slippage and repositioning, while adjacent high friction zones provide stable grasping. This local quality variation allows the system to switch between repositioning and stable grasping modes by engaging different surface regions.
4Ease of manufacture
If a uniform coefficient of friction is applied across the end effector surface, then manufacturing is simplified, but the ability to sense object properties through controlled slippage is reduced
Solution Approach 1:
The end effector surface features localized variations in friction properties that enable controlled slippage events. These slippage events provide tactile feedback that sensors can detect to infer object properties such as shape, texture, and compliance. The non-uniform friction distribution is engineered through techniques such as selective coating, surface texturing, or material composition variations.
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
Enhances robotic grasping and sensing capabilities by allowing objects to slide through the end effector while maintaining stable grip, facilitating efficient repositioning and property detection.
Implementation Method 1
The outer surface has a variable coefficient of friction. The variable coefficient of friction increases in a direction towards the base. The second end has a coefficient of friction greater than the coefficient of friction at the first end.
Data Source
AI summary
A plurality of collapsible protrusions extending from a base including a first end, a second end, a first surface, and an outer surface. The second end is opposite the first end. The first surface is distal from the base. The outer surface is between the first end and the second end. The outer surface has a variable coefficient of friction. The variable coefficient of friction increases in a direction towards the base. The second end has a coefficient of friction greater than the coefficient of friction at the first end.