Optical coherence tomography (OCT) has shown promise as a process sensor in selective laser sintering (SLS) due to its ability to yield depth-resolved data not attainable with conventional sensors. However, OCT images of nylon 12 powder and nylon 12 components fabricated via SLS contain artifacts that have not been previously investigated in the literature. A better understanding of light interactions with SLS powder and components is foundational for further research expanding the utility of OCT imaging in SLS and other additive manufacturing (AM) sensing applications. Specifically, in this work, nylon powder and sintered parts were imaged in air and in an index matching liquid. Subsequent image analysis revealed the cause of “signal-tail” OCT image artifacts to be a combination of both inter and intraparticle multiple-scattering and reflections. Then, the OCT imaging depth of nylon 12 powder and the contrast-to-noise ratio of a sintered part were improved through the use of an index matching liquid. Finally, polymer crystals were identified as the main source of intraparticle scattering in nylon 12 powder. Implications of these results on future research utilizing OCT in SLS are also given.
Selective laser sintering (SLS) is an efficient process in additive manufacturing that enables rapid part production from computer-based designs. However, SLS is limited by its notable lack of in situ process monitoring when compared with other manufacturing processes. We report the incorporation of optical coherence tomography (OCT) into an SLS system in detail and demonstrate access to surface and subsurface features. Video frame rate cross-sectional imaging reveals areas of sintering uniformity and areas of excessive heat error with high temporal resolution. We propose a set of image processing techniques for SLS process monitoring with OCT and report the limitations and obstacles for further OCT integration with SLS systems.
The US Army Future Combat System (FCS) will implement Unmanned Ground Vehicles (UGV) in numbers not
previously seen before in military operations. Many of these vehicles will also be larger and faster than the small robots
typically used today for explosive ordnance disposal and general improvised explosive device handling. More
importantly, FCS will implement these UGV's in scenarios were they will be in much closer proximity to soldiers and
other non-combatant personnel. This paper describes the plan for developing an appropriate match of technology for
autonomous UGV maneuver with the emerging need for safety release verification for these systems prior to fielding.
The plan is followed by descriptions of initial data collections with a UGV, that will form the starting point in this
safety release process, and stimulate further use and refinement of this process for large UGV's in applications beyond
A long-held dream for robotics researchers is the creation of vehicles that can move to a goal without human supervision, adapting as required to changing circumstances. While today’s ground robots are still far from achieving such complete autonomy, substantial progress has been attained. In this paper we describe the state-of-the-art in autonomous ground vehicle navigation as observed in the recently completed DARPA PerceptOR program, and we suggest new research directions where we see opportunities for leaps in performance.
The Army and Office of the Secretary of Defense agreed in May 2003 that the Future Combat Systems (FCS) Program had achieved sufficient maturity to pass what is referred to as "Milestone B." This milestone cleared the way for the Army and DARPA to award Boeing/SAIC FCS Lead System Integrator a 7 year System Design and Development Contract with options leading to production of systems and a Fielded Operational Capability in the year 2012. The breadth of the FCS Program is unique for DoD. It encompasses at least 7 variants of manned ground vehicles, 6 variants of unmanned ground vehicles, 4 unmanned aerial vehicles, unattended sensors, and the critical integration of these assets through a common Command/Control/Communications (C4ISR) backbone and protocol. As such, it has both internal program developments and strong linkages with existing programs in weapons, communications, sensors, command and control, and soldier integrated systems. An important new capability area for FCS is the integrated use of Unmanned Systems (both air and ground). This paper will deal with the LSI efforts associated with the UGV systems and additional detail will be available from the contractor teams working with us on each of these systems in later talks.
DARPA has been leading two programs under joint sponsorship with the Army which are directed at advancement of unmanned ground vehicle (UGV) technologies in support of the Future Combat Systems (FCS) Program. These two programs are intended to provide complimentary developments to allow the Army with its Lead Systems Integrator an expanded set of technology options as it goes through its system trade
studies. The data and experiences derived from these programs also increase understanding of current capabilities and future growth trends to aid in requirements definition for FCS UGV elements of the force structure. These two programs: Unmanned Ground Combat Vehicle (UGCV), and Perception for Off-Road Robotics (PerceptOR) will be described in this paper with comments on their current status.
Proc. SPIE. 4715, Unmanned Ground Vehicle Technology IV
KEYWORDS: Defense and security, Sensors, Robotics, Control systems, Fluorescence correlation spectroscopy, Defense technologies, Control systems design, Commercial off the shelf technology, Prototyping, Unmanned ground vehicles
The Defense Advanced Research Projects Agency (DARPA) and the US Army (ASAALT) have jointly funded several FCS research initiatives in ground robotics. The Unmanned Ground Combat Vehicle (UGCV) and Perception for Off-Road Mobility (PerceptOR) programs are the major elements of this joint ground robotic effort. These programs were initiated in fiscal year 2001 and have progressed through their first phase. The UGCV program, now in Phase IB, has downselected from 11 concepts designs to 4. Phase IB focuses on detailed design of teams' concepts in anticipation of the prototype construction Phase II and initial vehicle roll-out near the end of the 2002 calendar year. This paper highlights program findings to date as a result of the initial phase, and illustrates plans for Phase II prototype testing. The PerceptOR program, currently in Phase II, has completed its Phase I which involved development of a perception system for operation on a commercial All Terrain Vehicle. This paper describes the effort of the first phase, and outlines the plans for vehicle testing in Phases II and III.
As a study in late 1999, and subsequently as an official program in early 2000, the Army and DARPA agreed to jointly fund a research effort which became known as Future Combat Systems (FCS) to fast track the introduction of new capability to our ground forces which were increasingly being asked to respond rapidly to hostile situations around the world. The Chief of Staff of the Army clearly articulated this crucial need in his thrust to make the light forces more lethal and the heavy forces more deployable. The DARPA/Army agreement consisted of two parts: a) program to have industry lead teams develop concepts for how the FCS would be composed and integrated and b) a series of technology development programs which were expected to generate potentially radical improvements in the overall effectiveness of the FCS concept. Two of these technology development programs were directly related to ground vehicle robotics, and evolved by the end of 2000 to be the Unmanned Ground Combat Vehicle (UGCV) and Perception for Off-road Robotics (PerceptOR) programs. These programs and the underlying assumptions are described in this paper.