arXiv subjects

Malcolm Smith

Publications and source records attributed to Malcolm Smith.

9 recordsLinked to original sources

arXiv2026

MORFEO: Advancing Towards Final Design

The Multiconjugate adaptive Optics Relay For ELT Observations (MORFEO) is a first-generation adaptive optics module for the Extremely Large Telescope (ELT), designed to deliver a diffraction-limited, highly uniform 53x53 arcsec field of view to the MICADO near-infrared camera. As the project advances toward its Final Design Review (FDR), significant consolidations have been achieved across all subsystems. This paper presents an updated overview of the MORFEO system, highlighting its dual operational modes (MCAO and SCAO) and recent developments in its opto-mechanical architecture. We dedicate specific focus to the core adaptive hardware, detailing the fifth-generation post-focal deformable mirrors, the highly complex Laser Guide Star (LGS) objective zoom system required to track sodium layer variations, and the Natural Guide Star (NGS) low-order and reference sensing strategies. Furthermore, we detail the advanced pseudo-open-loop control strategy managed by a split Hard and Soft Real-Time Computer architecture. Finally, we report the latest end-to-end performance estimations obtained via the SPECULA simulation framework, demonstrating compliance with the stringent Strehl Ratio and sky coverage requirements under median atmospheric conditions.

astro-ph.IM↗

arXiv2024

HEART: automated build and test infrastructure for real-time controller development

The Herzberg Extensible Adaptive optics Real-Time Toolkit (HEART) is a complete framework written in C and Python for building next-generation adaptive optics (AO) system real-time controllers, with the performance needed for extremely large telescopes. With numerous HEART-based RTCs now in their design or build phases, each with different AO algorithms, target hardware, and observatory requirements, continuous automated builds and tests are a cornerstone of our development effort. In this paper we describe the many levels of testing that we perform, from low-level unit tests of individual functions, to more complex component and system-level tests that verify both numerical correctness and execution performance. Incorporating extensive testing into HEART since its inception has allowed us to continuously (and confidently) refactor and extend it to both meet the changing needs of local on-sky experiments, as well as those of the several major facility instruments that we are developing.

astro-ph.IM↗

arXiv2024

Amplifying the Kinematics of Origami Mechanisms With Spring Joints

Due to its rigid foldability and predictable kinematics, the reverse fold is the fundamental mechanism behind some of the most well known origami kinematic structures, including the Miura Ori, Yoshimura, and waterbomb patterns. However, the reverse fold only has one parameter to control its behavior: the starting fold angle. In this paper I introduce an alternative to the traditional reverse fold, based on the spring into action pattern, called the spring joint. This novel rigidly foldable mechanism is able to couple multiple reverse folds into a compact space to amplify the kinematic output of a traditional reverse fold by up to ten times, and to add one parameter for each reverse fold, giving more programmatic control of origami structures. Methods of parameterizing both the starting angle, the path of travel, and the axis of motion are also introduced. Unfortunately, this versatility comes at the cost of a large buildup of layers, making the spring joint impractical for thick origami mechanisms. To solve this problem, I also introduce a modular alternative to the spring joint that has no additional layers, with the same kinematic properties. Both of these mechanisms are tested as replacements for the reverse fold in both traditional and custom origami structures.

cs.RO↗

arXiv2023

Traffic Characteristics of Extended Reality

This tutorial paper analyzes the traffic characteristics of immersive experiences with extended reality (XR) technologies, including Augmented reality (AR), virtual reality (VR), and mixed reality (MR). The current trend in XR applications is to offload the computation and rendering to an external server and use wireless communications between the XR head-mounted display (HMD) and the access points. This paradigm becomes essential owing to (1) its high flexibility (in terms of user mobility) compared to remote rendering through a wired connection, and (2) the high computing power available on the server compared to local rendering (on HMD). The requirements to facilitate a pleasant XR experience are analyzed in three aspects: capacity (throughput), latency, and reliability. For capacity, two VR experiences are analyzed: a human eye-like experience and an experience with the Oculus Quest 2 HMD. For latency, the key components of the motion-to-photon (MTP) delay are discussed. For reliability, the maximum packet loss rate (or the minimum packet delivery rate) is studied for different XR scenarios. Specifically, the paper reviews optimization techniques that were proposed to reduce the latency, conserve the bandwidth, extend the scalability, and/or increase the reliability to satisfy the stringent requirements of the emerging XR applications.

cs.NI↗

arXiv2021

TXOP sharing with Coordinated Spatial Reuse in Multi-AP Cooperative IEEE 802.11be WLANs

IEEE 802.11be networks (aka Wi-Fi 7) will have to cope with new bandwidth-hungry and low-latency services such as eXtended Reality and multi-party cloud gaming. With this goal in mind, transmit opportunity (TXOP) sharing between coordinated access points (APs) may contribute to alleviating inter-AP contention, hence increasing the overall network throughput. This paper evaluates two coordinated TXOP sharing strategies: coordinated time division multiple access (c-TDMA) and coordinated-TDMA with spatial reuse (c-TDMA/SR). We show that, while c-TDMA alone does not result in any significant improvement in terms of the WLAN throughput, it lays the groundwork to implement coordinated SR (c-SR) techniques. To evaluate the performance of c-TDMA/SR, we propose a fair scheduler able to select the best subset of parallel transmissions in WLAN deployments, as well as the appropriate power levels to be used by APs and stations (STAs), leading to maximum performance. The results obtained for c-TDMA/SR show significant throughput gains compared with c-TDMA, with values higher than 140% in 90% of the considered scenarios.

cs.NI↗

arXiv2020

Traffic Characteristics of Virtual Reality over Edge-enabled Wi-Fi Networks

Virtual reality (VR) is becoming prevalent with a plethora of applications in education, healthcare, entertainment, etc. To increase the user mobility, and to reduce the energy consumption and production cost of VR head mounted displays (HMDs), wireless VR with edge-computing has been the focus of both industry and academia. However, transferring large video frames of VR applications with their stringent Quality of Service (QoS) requirements over wireless network requires innovations and optimizations across different network layers. In order to develop efficient architectures, protocols and scheduling mechanisms, the traffic characteristics of various types of VR applications are required. In this paper, we first compute the theoretical throughput requirements of an ideal VR experience as well as a popular VR HMD. We then examine the traffic characteristics of a set of VR applications using an edge-enabled Wi-Fi network. Our results reveal interesting findings that can be considered in developing new optimizations, protocols, access mechanisms and scheduling algorithms.

cs.NI↗

arXiv2014

NFIRAOS First Facility AO System for the Thirty Meter Telescope

NFIRAOS, the Thirty Meter Telescope's first adaptive optics system is an order 60x60 Multi-Conjugate AO system with two deformable mirrors. Although most observing will use 6 laser guide stars, it also has an NGS-only mode. Uniquely, NFIRAOS is cooled to -30 C to reduce thermal background. NFIRAOS delivers a 2-arcminute beam to three client instruments, and relies on up to three IR WFSs in each instrument. We present recent work including: robust automated acquisition on these IR WFSs; trade-off studies for a common-size of deformable mirror; real-time computing architectures; simplified designs for high-order NGS-mode wavefront sensing; modest upgrade concepts for high-contrast imaging.

astro-ph.IM↗

arXiv2014

Gemini Planet Imager One Button Approach

The Gemini Planet Imager (GPI) is an "extreme" adaptive optics coronagraph system that is now on the Gemini South telescope in Chile. This instrument is composed of three different systems that historically have been separate instruments. These systems are the extreme Adaptive Optics system, with deformable mirrors, including a high-order 64x64 element MEMS system; the Science Instrument, which is a near-infrared integral field spectrograph; and the Calibration system, a precision IR wavefront sensor that also holds key coronagraph components. Each system coordinates actions that require precise timing. The observatory is responsible for starting these actions and has typically done this asynchronously across independent systems. Despite this complexity we strived to provide an interface that is as close to a one-button approach as possible. This paper will describe the sequencing of these systems both internally and externally through the observatory.

astro-ph.IM↗

arXiv2009

Research Science and Education: The NSF's Astronomy and Astrophysics Postdoctoral Fellowship

The NSF's Astronomy and Astrophysics Postdoctoral Fellowship (AAPF) is exceptional among the available postdoctoral awards in Astronomy and Astrophysics. The fellowship is one of the few that allows postdoctoral researchers to pursue an original research program, of their own design, at the U.S. institution of their choice. However, what makes this fellowship truly unique is the ability of Fellows to lead an equally challenging, original educational program simultaneously. The legacy of this singular fellowship has been to encourage and advance leaders in the field who are equally as passionate about their own research as they are about sharing that research and their passion for astronomy with students and the public. In this positional paper we address the importance of fellowships like the AAPF to the astronomical profession by identifying the science and educational contributions that Fellows have made to the community. Further, we recommend that fellowships that encourage leading postdoctoral researchers to also become leaders in Astronomy education be continued and expanded.

astro-ph.IM↗