Ralph R. Peters

Automatic Design of 3-D Fixtures and Assembly Pallets:

This paper presents an implemented algorithm that automatically de signs fixtures and assembly pallets to hold three-dimensional parts. All fixtures generated by the algorithm employ round side locators, a side clamp, and cylindrical supports; depending on the value of an input-control flag, the fixture may also include swing-arm top clamps. Using these modular elements, the algorithm designs fix tures that rigidly constrain and locate a part, obey task constraints, are robust to part-shape variations, are easy to load, and are eco nomical to produce. For the class of fixtures that are considered, the algorithm is guaranteed to find the global optimum design that sat isfies these and other pragmatic conditions. We present the results of the algorithm applied to several practical manufacturing problems. For these complex problems, the algorithm typically returns initial high-quality fixture designs in less than a minute, and identifies the global optimum design in just over an hour. The algorithm is also capable of solving difficult design problems where a single fixture is desired that can hold either of two parts.

Automatic design of 3-d fixtures and assembly pallets

This paper presents an implemented algorithm that automatically designs fixtures and assembly pallets to hold three-dimensional parts. The designed fixtures rigidly constrain and locate the part, obey task constraints, are robust to part shape variations, are easy to load, and are economical to produce. The algorithm is guaranteed to find the global optimum solution that satisfies these and other pragmatic conditions. We present the results of the algorithm applied to several practical manufacturing problems. For these complex problems the algorithm typically returns initial high-quality fixture designs in less than two minutes, and identifies the global optimum design in just over an hour.

Forensic 3D Scene Reconstruction

Traditionally law enforcement agencies have relied on basic measurement and imaging tools, such as tape measures and cameras, in recording a crime scene. A disadvantage of these methods is that they are slow and cumbersome. The development of a portable system that can rapidly record a crime scene with current camera imaging, 3D geometric surface maps, and contribute quantitative measurements such as accurate relative positioning of crime scene objects, would be an asset to law enforcement agents in collecting and recording significant forensic data. The purpose of this project is to develop a fieldable prototype of a fast, accurate, 3D measurement and imaging system that would support law enforcement agents to quickly document and accurately record a crime scene.

Thermionic diode subsystem model

A model has been developed that predicts the electrical currents in thermionic diodes and heat transfer rates across the thermionic diode gaps for large networks of thermionic diodes. A computer code that implements this model has been written; eventually, this code will be incorporated into overall thermionic reactor system codes. The thermionic diode subsystem (TDS) model account for spatially‐dependent radial and axial temperature in the thermionic diodes. Standard techniques for iteratively solving this system of equations have not been successful so a procedure based on optimization techniques has been developed to solve this problem. Results of TDS calculations for TOPAZ II compare favorably with the available data. The TDS model will be validated against future TOPAZ II test results.

Simulated Mobile Self-Location Using 3D Range Sensing and an A-Priori Map

Self-location is a critical component of unmanned ground vehicle operation. While GPS has met this need for many applications, there are others, indoors and outdoors, where GPS is not available or reliable. This paper discusses the investigation of a method to self-locate using an onboard 3D range sensor, when a 3D map of the environment is available. We have examined the performance in terms of what is needed for data coverage and terrain types. Localization is accomplished through surface fitting. Surface fitting is an important component of Simultaneous Localization and Mapping (SLAM) for 3D terrains. Three environments were chosen for testing, including a hilly desert scene, an indoor corridor scene, and a forest scene. A simulated 3D range sensor was used to scan models corresponding to these three environments. Various parameters were modified to identify strong and weak points in the scheme.

Human Assisted Assembly Processes

Automatic assembly sequencing and visualization tools are valuable in determining the best assembly sequences, but without Human Factors and Figure Models (HFFMs) it is difficult to evaluate or visualize human interaction. In industry, accelerating technological advances and shorter market windows have forced companies to turn to an agile manufacturing paradigm. This trend has promoted computerized automation of product design and manufacturing processes, such as automated assembly planning. However, all automated assembly planning software tools assume that the individual components fly into their assembled configuration and generate what appear to be a perfectly valid operations, but in reality the operations cannot physically be carried out by a human. Similarly, human figure modeling algorithms may indicate that assembly operations are not feasible and consequently force design modifications; however, if they had the capability to quickly generate alternative assembly sequences, they might have identified a feasible solution. To solve this problem HFFMs must be integrated with automated assembly planning to allow engineers to verify that assembly operations are possible and to see ways to make the designs even better. Factories will very likely put humans and robots together in cooperative environments to meet the demands for customized products, for purposes including robotic and automated assembly. For robots to work harmoniously within an integrated environment with humans the robots must have cooperative operational skills. For example, in a human only environment, humans may tolerate collisions with one another if they did not cause much pain. This level of tolerance may or may not apply to robot-human environments. Humans expect that robots will be able to operate and navigate in their environments without collisions or interference. The ability to accomplish this is linked to the sensing capabilities available. Current work in the field of cooperative automation has shown the effectiveness of humans and machines directly interacting to perform tasks. To continue to advance this area of robotics, effective means need to be developed to allow natural ways for people to communicate and cooperate with robots just as they do with one another.

Features Automated assembly and fixture planning at Sandia National Laboratories

The Intelligent Systems and Robotics Center at Sandia National Laboratories supports several ongoing projects oriented towards enabling the creation of more automatic and effective robotic assembly systems, especially for small lot production. Two of these projects are Archimedes, which is an automatic assembly planning system, and HoldFast, which automatically designs optimal form‐closure fixtures. These technologies have application in many automated assembly contexts, whether robotic or not. Discusses the current state and applications of these two technologies. Both are based on use of a 3D CAD model, which currently must be converted to ACIS form for processing. Archimedes reasons about the liaisons between parts, then derives an assembly plan that is geometrically valid. This plan is improved by interaction with the user, who adds “constraints” to guide replanning. Facilities to define and search for a user’s “optimal” plan are under development. Given a workpiece shape, task constraints, and a description of a fixture kit, HoldFast finds the optimal fixture that can be made from the kit to hold the workpiece in form‐closure.