Efficient contact state graph generation for assembly applications

An important aspect in the design of many automated assembly strategies is the ability to automatically generate the set of contact states that may occur during an assembly task. In this paper, we present an efficient means of constructing the set of all geometrically feasible contact states that may occur within a bounded set of misalignments (bounds determined by robot inaccuracy). This set is stored as a graph, referred to as an Assembly Contact State Graph (ACSG), which indicates neighbor relationships between feasible states. An ACSG is constructed without user intervention in two stages. In the first stage, all hypothetical primitive principle contacts (PPCs; all contact states allowing 5 degrees of freedom) are evaluated for geometric feasibility with respect to part-imposed and robot-imposed restrictions on relative positioning (evaluated using optimization). In the second stage, the feasibility of each of the various combinations of PPCs is efficiently evaluated, first using topological existence and uniqueness criteria, then using part-imposed and robot-imposed geometric criteria.

Authors

• Feng Pan
• Joseph M. Schimmels

Keywords

• Robotic assembly
• Robots
• Orbital robotics
• Robotics and automation
• State-space methods
• Testing
• Industrial engineering
• Helium
• Motion planning
• Hybrid power systems
• Contact Conditions
• Automatic Generation
• User Intervention
• Neighborhood Relationship
• Unified Criteria
• Feasible States
• Formation Of Contacts
• Number Of Procedures
• User Input
• Surface Elements
• Boundary Element
• Geometric Conditions
• Level Of Constraint
• Edges Of Objects
• Set Of Faces
• High-level Description
• Description Of Space
• Single Point Of Contact