Robotic Fingertip Geometry for Stable Grasp Contact Primitives
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Solution Overview
Problem
Existing grasping techniques face challenges in achieving stable and robust grasping of various objects due to unrealistic point contact modeling, inability to generalize to novel objects, and vulnerability to uncertainties in positioning and friction coefficients, which limits their effectiveness in contact-level grasping.
Innovation Solution
The approach involves defining 'contact primitives' to represent classes of similar local geometries between fingertips and objects, clustering contact areas to optimize fingertip design, and using hierarchical grasp planning to maximize contact areas and ensure stable grasps, with fingertips designed to match local geometries using soft materials for improved robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If point contact modeling is used for grasping, then the grasping model is simple, but the grasp stability is poor and unrealistic
Solution Approach 1:
The patent segments the continuous contact surface into discrete contact patches, where each patch represents a localized area of contact between the fingertip and object. This segmentation allows the system to model distributed contact forces across multiple patches rather than relying on a single point contact, thereby improving grasp stability while maintaining computational tractability through the discrete patch representation
Solution Approach 2:
The patent transitions from zero-dimensional point contact modeling to two-dimensional contact patch modeling by introducing spatial extent to contact areas. This dimensional expansion allows the model to capture the distribution of contact pressures and forces across the fingertip surface, providing more realistic and stable grasping predictions without excessive complexity
2Device complexity
If traditional grasping techniques are used, then the method is simple, but the adaptability to novel objects is poor
Solution Approach 1:
The patent performs preliminary clustering of contact patches into contact primitives during an offline training phase, organizing contact data by local geometry characteristics before actual grasping tasks. This preliminary organization enables the system to quickly match and generalize to novel objects during online operation without requiring complex real-time analysis, thereby improving adaptability while controlling complexity
Solution Approach 2:
The patent changes the parameter representation from raw contact coordinates to clustered contact primitive categories that capture essential geometric features. By transforming contact patch data into discrete primitive types characterized by local geometry properties, the system achieves better generalization to novel objects while maintaining a manageable complexity through parameter discretization and clustering
3Measurement precision
If explicit contact modeling is used, then analytic force calculation is enabled, but the sensitivity to positioning and friction uncertainties increases
Solution Approach 1:
The patent merges multiple contact patches into clustered contact primitives that represent families of similar contact geometries. This merging reduces the number of individual force calculations required while maintaining analytic capability, and simultaneously improves robustness by averaging out the effects of positioning and friction uncertainties across the clustered group rather than being sensitive to individual patch variations
Data Source
AI summary
Techniques for fingertip design are disclosed that leverage how most grasp contacts can share a few classes of local geometries. In order to maximize the contact areas for achieving more robust grasps, contact primitives, which represent a set of contacts of similar local geometries, are identified. A uniform cost algorithm, which can be formulated as a decision making process in a tree structure, can be utilized to cluster a set of example grasp contacts into a finite set of one or more contact primitives. Fingertips can be designed by optimization to match the local geometry of each contact primitive, and then fingertips can be 3D printed using soft materials to compensate for optimization residuals. For novel objects, an approach to generate grasp contacts that match the fingertip geometries while together forming stable grasps can be utilized.