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Communication and position sensing are among the most important capabilities for swarm robots to interact with their peers and perform tasks collaboratively. However, the hardware required to facilitate communication and position sensing is often too complicated, expensive, and bulky to be carried on swarm robots. Here we present Maneuverable Piccolissimo 3 (MP3), a minimalist, single motor drone capable of executing inter-robot communication via infrared light and triangulation-based sensing of relative bearing, distance, and elevation using message arrival time. Thanks to its novel design, MP3 can communicate with peers and localize itself using simple components, keeping its size and mass small and making it inherently safe for human interaction. We present the hardware and software design of MP3 and demonstrate its capability to localize itself, fly stably, and maneuver in the environment using peer-to-peer communication and sensing.

Here we present Rollbot, the first spherical robot capable of controllably maneuvering on 2D plane with a single actuator. Rollbot rolls on the ground in circular pattern and controls its motion by changing the curvature of the trajectory through accelerating and decelerating its single motor and attached mass. We present the theoretical analysis, design, and control of Rollbot, and demonstrate its ability to move in a controllable circular pattern and follow waypoints., Comment: Submission to IROS 2024

Complexity, cost, and power requirements for the actuation of individual robots can play a large factor in limiting the size of robotic swarms. Here we present PCBot, a minimalist robot that can precisely move on an orbital shake table using a bi-stable solenoid actuator built directly into its PCB. This allows the actuator to be built as part of the automated PCB manufacturing process, greatly reducing the impact it has on manual assembly. Thanks to this novel actuator design, PCBot has merely five major components and can be assembled in under 20 seconds, potentially enabling them to be easily mass-manufactured. Here we present the electro-magnetic and mechanical design of PCBot. Additionally, a prototype robot is used to demonstrate its ability to move in a straight line as well as follow given paths., Comment: Accepted by IROS 2022, best paper and best mechanism design paper finalist

Despite their growing popularity, swarms of robots remain limited by the operating time of each individual. We present algorithms which allow a human to sculpt a swarm of robots into a shape that persists in space perpetually, independent of onboard energy constraints such as batteries. Robots generate a path through a shape such that robots cycle in and out of the shape. Robots inside the shape react to human initiated changes and adapt the path through the shape accordingly. Robots outside the shape recharge and return to the shape so that the shape can persist indefinitely. The presented algorithms communicate shape changes throughout the swarm using message passing and robot motion. These algorithms enable the swarm to persist through any arbitrary changes to the shape. We describe these algorithms in detail and present their performance in simulation and on a swarm of mobile robots. The result is a swarm behavior more suitable for extended duration, dynamic shape-based tasks in applications such as agriculture and emergency response., Comment: 20 pages, 17 figures

Human-swarm interaction is facilitated by a low-dimensional encoding of the swarm formation, independent of the (possibly large) number of robots. We propose using image moments to encode two-dimensional formations of robots. Each robot knows its pose and the desired formation moments, and simultaneously estimates the current moments of the entire swarm while controlling its motion to better achieve the desired group moments. The estimator is a distributed optimization, requiring no centralized processing, and self-healing, meaning that the process is robust to initialization errors, packet drops, and robots being added to or removed from the swarm. Our experimental results with a swarm of 50 robots, suffering nearly 50% packet loss, show that distributed estimation and control of image moments effectively achieves desired swarm formations.

Beyond unicellular and multicellular organisms, there is a third type of structural complexity in living animals: that of the mechanical self-assembly of groups of distinct multicellular organisms into dynamical, functional structures. One of the most striking examples of such structures is the army ant bivouac, a nest which self-assembles solely from the interconnected bodies of hundreds of thousands of individuals. These bivouacs are difficult to study because they rapidly disassemble when disturbed, and hence little is known about the structure and rules that individuals follow during their formation. Here we use a custom-built Computed Tomography scanner to investigate the details of the internal structure and growth process of army ant bivouacs. We show that bivouacs are heterogeneous structures, which throughout their growth maintain a thick shell surrounding a less dense interior that contains empty spaces akin to nest chambers. We find that ants within the bivouac do not carry more than approximately eight times their weight regardless of the size of the structure or their position within it. This observation suggests that bivouac size is not limited by physical constraints of the ants' morphology. This study brings us closer to understanding the rules used by individuals to govern the formation of these exceptional superorganismal structures, and provides insight into how to create engineered self-assembling systems with, for instance, swarms of robots or active matter.

The use of computed tomography (CT) imaging has become of increasing interest to academic areas outside of the field of medical imaging and industrial inspection, e.g., to biology and cultural heritage research. The pecularities of these fields, however, sometimes require that objects need to be imaged on-site, e.g., in field-work conditions or in museum collections. Under these circumstances, it is often not possible to use a commercial device and a custom solution is the only viable option. In order to achieve high image quality under adverse conditions, reliable calibration and trajectory reproduction are usually key requirements for any custom CT scanning system. Here, we introduce the construction of a low-cost disassemblable CT scanner that allows calibration even when trajectory reproduction is not possible due to the limitations imposed by the project conditions. Using 3D-printed in-image calibration phantoms, we compute a projection matrix directly from each captured X-ray projection. We describe our method in detail and show successful tomographic reconstructions of several specimen as proof of concept., Comment: This paper was originally published at the 6th International Conference on Image Formation in X-Ray Computed Tomography (CTmeeting 2020)

In this paper, we consider the problem of planar graph-based simultaneous localization and mapping (SLAM) that involves both poses of the autonomous agent and positions of observed landmarks. We present CPL-SLAM, an efficient and certifiably correct algorithm to solve planar graph-based SLAM using the complex number representation. We formulate and simplify planar graph-based SLAM as the maximum likelihood estimation (MLE) on the product of unit complex numbers, and relax this nonconvex quadratic complex optimization problem to convex complex semidefinite programming (SDP). Furthermore, we simplify the corresponding complex semidefinite programming to Riemannian staircase optimization (RSO) on the complex oblique manifold that can be solved with the Riemannian trust region (RTR) method. In addition, we prove that the SDP relaxation and RSO simplification are tight as long as the noise magnitude is below a certain threshold. The efficacy of this work is validated through applications of CPL-SLAM and comparisons with existing state-of-the-art methods on planar graph-based SLAM, which indicates that our proposed algorithm is capable of solving planar graph-based SLAM certifiably, and is more efficient in numerical computation and more robust to measurement noise than existing state-of-the-art methods. The C++ code for CPL-SLAM is available at https://github.com/MurpheyLab/CPL-SLAM.

This study examined the role of Title I in 18 secondary schools (9 intermediate and 9 high schools) that serve disadvantaged students, are engaged in comprehensive school improvement efforts, and have consistently high or improving student achievement. The study was prompted by the changes to Title I under the 1994 Improving America's Schools Act. The schools in the study reflect geographic and racial or ethnic diversity and use varied approaches to school improvement. Data were collected in 3-day site visits, with interviews with administrators and instructional staff. The schools relied on three major strategies to improve and maintain the quality of teaching in their classrooms: (1) providing teachers with multiple opportunities to expand their professional expertise; (2) instituting school accountability systems that require students to demonstrate their intellectual growth; and (3) using data collection and analysis to guide the school's decisions. The larger middle schools and half of the high schools created smaller learning communities to combat the impersonality of the large schools. They attempted to engage students in the life of the school, offered support services for students, and made strong efforts to involve parents. For the schools in the study, Title I provided valuable academic assistance, and, although Title I played a limited role in supporting other elements of schoolwide improvement efforts, it did not impede such efforts. District Title I coordinators exerted minimal control over the schools' use of Title I resources. The findings show that if federal policymakers want Title I to play a prominent role in promoting higher standards and improved achievement in secondary schools, they will have to find ways to give the program more leverage in the schools. Implications for federal, state, and local policies are discussed. (Contains 21 references.) (SLD)

This report describes the results from an exploratory project conducted for the National Center for Education Statistics. The purpose of the project was to develop and field test questionnaire items and related methods designed to capture information about the instructional processes used nationally in 8th- to 12th-grade mathematics classrooms. Data from classroom observers, short logs of daily classroom practice, and a teacher questionnaire were used to assess the quality of the items. A survey questionnaire, field tested with 100 teachers, was completed by approximately 300 mathematics teachers, and a case study was conducted with 41 teachers in similar settings with comparable responsibilities. Results of these studies were used to make 10 recommendations to improve the field test validation process and the survey items. Thirteen appendixes contain supplemental information about the study and the test items. Appendix M contains a summary, in chart form, of recommended changes to the field test items. (Contains 21 references.) (SLD)

This document examines the implementation and early effects of Minnesota's open-enrollment option, which allows families to apply to enroll their children in a public school in any nonresident school district in the state. During 1989-90, surveys were mailed to 2,663 participating families, 1,966 secondary school students, and all 432 district superintendents. Usable responses were received from 1,377 families, 645 students, and 338 superintendents. Findings indicate that very few of the participating districts reported significant changes in their enrollments. Also, the information dissemination strategies used most often by districts were not the most effective means of reaching minority families. Parents identified the school's academic reputation as the most important reason for using the open-enrollment option. However, minority parents also considered the availability of child care and extracurricular activities, while low-income families were concerned with school proximity. Overall, the initial impacts appear to be modest, but in a positive direction. Other trends include a slight migration of families from urban to suburban districts and from lower-income to higher-income districts, and ambiguities that exist between regulations for federal categorical programs and state interdistrict choice programs. Ten figures, 14 tables, and an executive summary are included. Appendices contain a description of the study methodology and copies of the surveys. (Contains 12 references.) (LMI)