The Robot Operating System 2 (ROS 2) is rapidly impacting the intelligent machines sector - on space missions, large agriculture equipment, multi-robot fleets, and more. Its success derives from its focused design and improved capabilities targeting product-grade and modern robotic systems. Following ROS 2's example, the mobile robotics ecosystem has been fully redesigned based on the transformed needs of modern robots and is experiencing active development not seen since its inception. This paper comes from the desks of the key ROS Navigation maintainers to review and analyze the state of the art of robotics navigation in ROS 2. This includes new systems without parallel in ROS 1 or other similar mobile robotics frameworks. We discuss current research products and historically robust methods that provide differing behaviors and support for most every robot type. This survey consists of overviews, comparisons, and expert insights organized by the fundamental problems in the field. Some of these implementations have yet to be described in literature and many have not been benchmarked relative to others. We end by providing a glimpse into the future of the ROS 2 mobile robotics ecosystem.

As an artform, theatre provides a useful lens with which to explore issues in human-robot interaction[1, 2]. This is particularly useful when technology in question does not exist yet. However, because of its scripted nature, robots in the theatre can execute actions in a way that makes it appear as though they are actually having complex social interactions in ways that are not feasible with current algorithms. Furthermore, having real robots portray robotic characters lends a verisimilitude to the performance in a way that a human actor could not, leading to potentially greater emotional investment in the story. The production discussed here is the capstone in a long collaboration between the Computer Science and Performing Arts departments at Washington University in St. Louis. The script was commissioned for this particular production, written to feature Willow Garage’s PR2 robot alongside human actors. The play, Sky Sky Sky, by Liza Birkenmeier, focuses on the relationship between elderly patients near the end of their lives and their robotic caregivers. This subject was chosen given the prevalence of research on robotic assistance for the growing geriatric population in recent years. In the year 2061, an independent woman named Joan suffers a heart attack and cannot take care of herself anymore. She ends up with robotic medical support that accompanies her until her eventual death. Although the relationship starts off frostily, Joan ultimately comes to respect and rely on her companion, naming it Jane. During their interactions, the robot brings Joan food, helps her eat, keeps her warm, brushes her hair and helps her move around. Many of these tasks would be implausible (and possibly unsafe) to do with current technology , but were realized on stage through careful staging of repeated actions. Props were placed in precise locations to aid in the robot finding them, much as spike marks are used to place things for human actors. Integrating a real robot into a theatrical production provided some unique challenges from the artistic and algorithmic sides. Before the robot was integrated into the rehearsal process, the robot’s physical actions were initially performed and recorded by a human actor who was trained in both

Since its official introduction in 2012, the Robot Web Tools project has grown tremendously as an open-source community, enabling new levels of interoperability and portability across heterogeneous robot systems, devices, and front-end user interfaces. At the heart of Robot Web Tools is the rosbridge protocol as a general means for messaging ROS topics in a client-server paradigm suitable for wide area networks, and human-robot interaction at a global scale through modern web browsers. Building from rosbridge, this paper describes our efforts with Robot Web Tools to advance: 1) human-robot interaction through usable client and visualization libraries for more efficient development of front-end human-robot interfaces, and 2) cloud robotics through more efficient methods of transporting high-bandwidth topics (e.g., kinematic transforms, image streams, and point clouds). We further discuss the significant impact of Robot Web Tools through a diverse set of use cases that showcase the importance of a generic messaging protocol and front-end development systems for human-robot interaction.

With mobile robots moving into day to day life in private homes, care, or in public spaces and outdoors as robotic guides, Human-Robot Spatial Interaction (HRSI) - the study of joint movement of humans and robots and the social signals governing the interaction - becomes more and more important. The main focus of the workshop lies in incorporating social norms, like proxemics, and social signals, like eye contact and motioning, into current navigation approaches, be it constraint-based, learned from observation/demonstration, or interactively. How to evaluate the quality of the HRSI using novel feedback measures and devices, and grounding HRSI in empiric experiments focusing on Human-Human Spatial Interaction. The overall aim is to bring together participants from different fields, looking at all aspects of HRSI by presenting their work and identifying the main problems and questions on the way to a holistic, integrated HRSI system.

Many navigation systems, including the ubiquitous ROS navigation stack, perform path-planning on a single costmap, in which the majority of information is stored in a single grid. This approach is quite successful at generating collision-free paths of minimal length, but it can struggle in dynamic, people-filled environments when the values in the costmap expand beyond occupied or free space. We have created and implemented a new method called layered costmaps, which work by separating the processing of costmap data into semantically-separated layers. Each layer tracks one type of obstacle or constraint, and then modifies a master costmap which is used for the path planning. We show how the algorithm can be integrated with the open-source ROS navigation stack, and how our approach is easier to fine-tune to specific environmental contexts than the existing monolithic one. Our design also results in faster path planning in practical use, and exhibits a cleaner separation of concerns that the original architecture. The new algorithm also makes it possible to represent complex cost values in order to create navigation behavior for a wide range of contexts.

Effective robot navigation in the presence of humans is hard. Not only do human obstacles move, they react to the movements of the robot according to instinct and social rules. In order to efficiently navigate around each other, both the robot and the human must move in a way that takes the other into account. Failure to do so can lead to a lowering of the perceived quality of the interaction and, more importantly, it can also delay one or both parties, causing them to be less efficient in whatever task they are trying to achieve. In this paper, we present a system capable of creating more efficient corridor navigation behaviors by manipulating existing navigation algorithms and introducing social cues from the robot to the human. We give the results of a user study, demonstrating the effectiveness of our system, and discuss how it can be applied more generally to a wide variety of situations.

Human-Robot Interaction literature frequently uses Gaussian distributions within navigation costmaps to model proxemic constraints around humans. While it has proven to be effective in several cases, this approach is often hard to tune to get the desired behavior, often because of unforeseen interactions between different elements in the costmap. There is, as far as we are aware, no general strategy in the literature for how to predictably use this approach.In this paper, we describe how the parameters for the soft constraints can affect the robot's planned paths, and what constraints on the parameters can be introduced in order to achieve certain behaviors. In particular, we show the complex interactions between the Gaussian's parameters and elements of the path planning algorithms, and how undesirable behavior can result from configurations exceeding certain ratios. There properties are explored using mathematical models of the paths and two sets of tests: the first using simulated costmaps, and the second using live data in conjunction with the ROS Navigation algorithms.

Every year, tens of thousands of middle school and high school students participate in robotics competitions, such as Botball, FIRST, and VEX. This provides them with an excellent introduction to the ins and outs of building robots and programming them to autonomously accomplish specific tasks. However, the rules of many of these competitions often limit or prohibit human interaction with the robots. As a result, students are not exposed to and are, thus, not encouraged to think about human-robot interaction (HRI) and its potential impacts on society. To start getting a new generation of students thinking about HRI, a workshop was held entitled “Expressive Robotics: Motion and Emotion” at the 2011 Global Conference on Educational Robotics. The focus of the workshop was to teach the students how to program robots to express emotion and intent just through the robot's physical actions. The robot used by each participating group was not unlike the ones they used in competitions: an iRobot Create base provided a mobile platform, upon which stood a three degree-of-freedom arm, serving as an articulated spine and head. The students were then tasked with implementing a simple keyframe animation system to control the robot's limited degrees of freedom, which they could then modify to illustrate certain principles from theatre and animation. They used their animation system to tell a story purely through robot motion and interactions with props. The exposure to sociable robotics has the potential to increase interest and self-efficacy of underrepresented student populations, particularly girls, in STEM-related activities.

There are an increasing number of theatrical productions that involve mobile robots functioning as characters. The underlying systems that drive their performances can vary in numerous ways, including the level of adaptive control and the level of human involvement. However, oftentimes all of the performances as labeled equally as “robot acting,” hiding numerous possible complexities and simplifications in the programming. This paper aims to categorize and classify the different algorithms that can exist behind the curtain to create these performances.

Robots of varying kinds are appearing with increasing frequency in all manner of staged theatrical productions (see [1] and [2] for examples). While the individual productions are often greeted with positive receptions from their audiences, it is difficult to determine how the general public may react to the very idea of robots on stage acting alongside humans. While robots are growing more capable of the task, people are often hesitant at introducing technology into older art forms. One way to gauge opinions is to poll social networks. A short survey was linked to on the social networking sites Facebook, Google+ and Reddit. Using self-reported ratings of involvement with theatre and involvement with technology, respondents were separated into one of four groups: those involved with both theatre and technology (N=53), just theatre (N=19), just technology (N=49), and neither (N=1). They answered the question“How comfortable do you feel with the idea of robot actors performing alongside human actors on the stage?” on a scale from 1 to 5. The percentage of comforable respondants (answering 4 or 5) was 47% for both fields, 67% for just technology, and 15% for just theatre. BODY People involved with both theatre & technology are more comfortable with acting robots than just theatre people, but less so than techies.

Given the difficulty of social human-robot interaction (HRI), finding an appropriate conceptual model, as well as a useful venue to test the model, is key. While most work in social HRI draws insight and inspiration from the field of social psychology, this paper explores the philosophical backing and benefits of using ideas from theatre to frame social interactions. We present an analogy to Searle's Chinese Room argument to motivate the expressive challenges faced by human actors and by robots in social situations. We then compare the elements of theatre with the elements of HRI, and discuss techniques that we believe will lead to improved interactions.

Polonius is a robot control interface designed for running Wizard of Oz style experiments. It is designed to be easy enough to be used by the non-programmer collaborators of roboticists. The program acts as an intermediary between the robot and a wizard interacting with a GUI based on a pre-defined script. Polonius also eliminates the need for coding the video after experiments by integrating a robust logging system.

In this paper, we describe our initial experiences using a mobile robot as a teaching aid in a stage movement class, taught in the Performing Arts Department of Washington University in St. Louis. The robot participated in a number of exercises, intended to teach the fundamentals of movement, and interacted closely with human acting students. We describe these exercises, what they are designed to teach the students, and discuss how using a robot as a teaching aid can enhance the students' experience. We describe two classes in which a robot participated, one under tele-operation and one fully autonomously, and discuss both the students' reaction to the robots, and our subjective evaluations of the systems success.

MOTIVATION The most accurate way to determine the intron-exon structures in a genome is to align spliced cDNA sequences to the genome. Thus, cDNA-to-genome alignment programs are a key component of most annotation pipelines. The scoring system used to choose the best alignment is a primary determinant of alignment accuracy, while heuristics that prevent consideration of certain alignments are a primary determinant of runtime and memory usage. Both accuracy and speed are important considerations in choosing an alignment algorithm, but scoring systems have received much less attention than heuristics. RESULTS We present Pairagon, a pair hidden Markov model based cDNA-to-genome alignment program, as the most accurate aligner for sequences with high- and low-identity levels. We conducted a series of experiments testing alignment accuracy with varying sequence identity. We first created 'perfect' simulated cDNA sequences by splicing the sequences of exons in the reference genome sequences of fly and human. The complete reference genome sequences were then mutated to various degrees using a realistic mutation simulator and the perfect cDNAs were aligned to them using Pairagon and 12 other aligners. To validate these results with natural sequences, we performed cross-species alignment using orthologous transcripts from human, mouse and rat. We found that aligner accuracy is heavily dependent on sequence identity. For sequences with 100% identity, Pairagon achieved accuracy levels of >99.6%, with one quarter of the errors of any other aligner. Furthermore, for human/mouse alignments, which are only 85% identical, Pairagon achieved 87% accuracy, higher than any other aligner. AVAILABILITY Pairagon source and executables are freely available at http://mblab.wustl.edu/software/pairagon/

Polyphonic music transcription is a computationally dicult problem that is still widely regarded as unsolved. This paper describes one method for the problem of pitch recognition with multiple instruments. A genetic algorithm produces generations of possible transcriptions that are evaluated for fitness by comparing the transcription's generated audio to the original sound file. By sharing and modifying the genetic material of thousand of individual possible transcriptions, ultimately, the algorithm arrives at an accurate transcription for the original audio, or at least something that produces a similar wave form.