Robotic In-Gripper Repositioning Using Polyhedral Motion Cones
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Solution Overview
Problem
Current robotic systems face challenges in efficiently and accurately manipulating objects in three-dimensional environments using frictional pushes, as existing computational methods either sacrifice efficiency or realism, and three-dimensional motion cones are costly in terms of computing resources and introduce complexities due to gravitational wrenches.
Innovation Solution
The method involves generating a polyhedral approximation of the motion cone, which accounts for gravity, mass, and friction coefficients, allowing for quasi-static movement and stable frictional pushes, enabling robust and efficient manipulation of objects in three-dimensional spaces by iteratively sampling and prioritizing displacements based on cost-analysis systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If three-dimensional motion cones are used for robotic manipulation, then the realism and accuracy of frictional push simulation is improved, but the computational cost and system complexity increases
Solution Approach 1:
The motion cone is segmented into a finite set of discrete motion rays. Instead of continuously simulating all possible frictional push directions in three-dimensional space, the patent discretizes the motion cone into a manageable number of rays, each representing a feasible motion direction. This segmentation reduces the computational burden while preserving the essential physics of frictional contact.
Solution Approach 2:
The patent uses simplified geometric representations (polyhedral cones) to approximate the complex frictional contact dynamics. These simplified models act as computationally inexpensive proxies that capture the essential behavior without requiring expensive real-time simulations of full contact mechanics.
2Reliability
If standard complementarity formulations of contact dynamics are used, then the physical realism is improved, but the computational efficiency and ease of implementation deteriorates
Solution Approach 1:
The patent replaces the complex mechanical contact dynamics simulation with a geometric approach using motion cones. Instead of solving complementarity formulations that model frictional contact forces, the system uses pre-computed motion cones that directly represent feasible motions, substituting a difficult computational mechanics problem with a simpler geometric reasoning task.
Solution Approach 2:
The motion cones are pre-computed based on the object's geometry, mass, and friction coefficients. This preliminary computation captures the essential physics of frictional contact in advance, allowing the robotic system to plan maneuvers using simple geometric queries rather than performing expensive real-time physics simulations during execution.
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 simplifies and enhances the robustness of frictional pushing strategies, allowing for accurate control of object position and orientation in three-dimensional environments with reduced computational costs and improved resolution, enabling autonomous robotic manipulation without the need for specialized tooling or planning.
Implementation Method 1
A frictional contact may apply a frictional push to an object. The method may include applying a displacement to the object relative to the gripper according to one of the set of physically possible displacements using the frictional push. In some embodiments, applying the displacement to the object may further comprise at least one pusher frictionally pushing the object relative to the gripper.
Data Source
AI summary
Embodiments described herein relate to systems and methods for manipulating the position and/or orientation of an object while it is held in a robotic gripper. In one such embodiment, one or more physically possible and stable displacements for moving an object relative to a gripper using one or more frictional pushes may be determined and applied to the object to move the object from a first position and orientation to a second position and orientation while the object is held by the gripper. In certain embodiments, the physically possible and stable displacements may be determined using an appropriate motion cone approximation.