Advanced mobile manipulators offer the manufacturing industry the potential of a highly adaptive system to perform precision assembly tasks in agile environments. Developing performance measurement capabilities for mobile manipulator systems will support the advancement of manipulator-vehicle coordination, precision, accuracy, and robustness. The National Institute of Standards and Technology (NIST) developed a measurement methodology for advanced mobile manipulators, which are mobile robots with an onboard robot arm, each from a different manufacturer and with a different controller. The measurement methodology is designed to assess the performance of mobile manipulators for manufacturing applications such as assembly, where position and orientation accuracy are critically important. The proposed methodology used an artifact designed at NIST to simulate an assembly task station. An optical tracking system measured the location of the targets, the mobile base position and orientation, and the position of a manipulator end-of-arm tool. The experimental data collected, using three different system computers, were timestamped using local clocks synchronized via the NIST internal and local area networks to align the data streams. The mobile manipulator system, the experimental methodology, the data analysis, and the results of the measurement methodology uncertainty and mobile manipulator positioning uncertainty using the novel artifacts are described in this paper. For the system tested, the mobile manipulator detection of 2 mm diameter fiducials can be achieved after registration. With validation from the optical tracking system, the study demonstrated that the Reconfigurable Mobile Manipulator Artifact (RMMA) has potential for serving as a novel standalone, low-cost test method for measuring the positioning uncertainty of mobile manipulators within a measurement uncertainty of 2 mm.

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Executive SummaryCorrect time and timing is one of the foundational elements in enabling the communication and orchestration of technologies for accurate and optimal wide area monitoring, protection and control (WAMPAC) in the power industry. The National Institute of Standards and Technology (NIST) and the International Electrical and Electronic Engineer -Standard Association (IEEE-SA) conducted a workshop to gather inputs from stakeholders to identify, analyze, and provide guidance on technologies, standards and methodologies for addressing the practical timing challenges that are currently being experienced in wide area time synchronization.One of the key drivers for the workshop is the need to prioritize NIST efforts in addressing precision timing needs in power systems. NIST has established a Smart Grid Testbed, which includes the Precision Timing module to support the IEEE 1588 Power Profile efforts and to serve as a basis for timing measurement and security research. The objective of the workshop was to identify the timing challenges, the community of experts, and potential collaborators as well as key research priorities to guide future efforts to ensuring that the integrity, availability, accuracy, and precision of timing requirements are met in power systems.Precision timing synchronization with requirements ranging from one microsecond to hundreds of nanoseconds within and across substations is currently being characterized and monitored by utilities in order to advance capabilities in real-time measurement and control and to reap the economic and environmental benefits of more intelligent and efficient use of generation and storage resources while meeting customer demands. The proliferation of widely deployed smart sensors for WAMPAC, distribution and energy management systems, along with the increasing need for fault detection and location as well as maintaining system stability in real time using spatio-temporal and temporalfrequency analyses, all require precision timing. These new capabilities offer increased flexibility to grid operators, but they also raise new security concerns.Among the concerns expressed include timing discontinuities such as leap seconds, Daylight Savings Time, and GPS Week Number Rollovers. Additionally, the increasing prevalence of jamming and the potential for spoofing is leading security, time and network experts in power systems or other domains to explore alternative propagation methods of traceable time. These include eLOng-RAnge Navigation (eLORAN), Iridium, IEEE 1588 Precision Time Protocol (PTP), Network Time Protocol (NTP), radio (WWVB is the NIST operated time signal radio station near Fort Collins, Colorado.), atomic clocks, and other terrestrial and satellite-based timing propagation solutions.Given the current stage of exploration and characterization for real time control, utilities and system integrators identified the top industry challenge to be integrity assurance, with the first steps being device conformance and interoperability testing, performance mo...

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