Field Testing of a Stochastic Planner for ASV Navigation Using Satellite Images

We introduce a multi-sensor navigation system for autonomous surface vessels (ASV) intended for water-quality monitoring in freshwater lakes. Our mission planner uses satellite imagery as a prior map, formulating offline a mission-level policy for global navigation of the ASV and enabling autonomous online execution via local perception and local planning modules. A significant challenge is posed by the inconsistencies in traversability estimation between satellite images and real lakes, due to environmental effects such as wind, aquatic vegetation, shallow waters, and fluctuating water levels. Hence, we specifically modelled these traversability uncertainties as stochastic edges in a graph and optimized for a mission-level policy that minimizes the expected total travel distance. To execute the policy, we propose a modern local planner architecture that processes sensor inputs and plans paths to execute the high-level policy under uncertain traversability conditions. Our system was tested on three km-scale missions on a Northern Ontario lake, demonstrating that our GPS-, vision-, and sonar-enabled ASV system can effectively execute the mission-level policy and disambiguate the traversability of stochastic edges. Finally, we provide insights gained from practical field experience and offer several future directions to enhance the overall reliability of ASV navigation systems.Comment: 33 pages, 20 figures. Project website https://pcctp.github.io. arXiv admin note: text overlap with arXiv:2209.1186

Belief Representations for Planning with Contact Uncertainty

While reaching for your morning coffee you may accidentally bump into the table, yet you reroute your motion with ease and grab your cup. An effective autonomous robot will need to have a similarly seamless recovery from unexpected contact. As simple as this may seem, even sensing this contact is a challenge for many robots, and when detected contact is often treated as an error that an operator is expected to resolve. Robots operating in our daily environments will need to reason about the information they have gained from contact and replan autonomously. This thesis examines planning under uncertainty with contact sensitive robot arms. Robots do not have skin and cannot precisely sense the location of contact. This leads to the proposed Collision Hypothesis Set model for representing a belief over the possible occupancy of the world sensed through contact. To capture the specifics of planning in an unknown world with this measurement model, this thesis develops a POMDP approach called the Blindfolded Traveler's Problem. A good prior over the possible obstacles the robot might encounter is key to effective planning. This thesis develops a neural network approach for sampling potential obstacles that are consistent with both what a robot sees from its camera and what it feels through contact.PHDRoboticsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/169845/1/bsaund_1.pd

From Data to Actions in Intelligent Transportation Systems: A Prescription of Functional Requirements for Model Actionability

Advances in Data Science permeate every field of Transportation Science and Engineering, resulting in developments in the transportation sector that are data-driven. Nowadays, Intelligent Transportation Systems (ITS) could be arguably approached as a “story” intensively producing and consuming large amounts of data. A diversity of sensing devices densely spread over the infrastructure, vehicles or the travelers’ personal devices act as sources of data flows that are eventually fed into software running on automatic devices, actuators or control systems producing, in turn, complex information flows among users, traffic managers, data analysts, traffic modeling scientists, etc. These information flows provide enormous opportunities to improve model development and decision-making. This work aims to describe how data, coming from diverse ITS sources, can be used to learn and adapt data-driven models for efficiently operating ITS assets, systems and processes; in other words, for data-based models to fully become actionable. Grounded in this described data modeling pipeline for ITS, we define the characteristics, engineering requisites and challenges intrinsic to its three compounding stages, namely, data fusion, adaptive learning and model evaluation. We deliberately generalize model learning to be adaptive, since, in the core of our paper is the firm conviction that most learners will have to adapt to the ever-changing phenomenon scenario underlying the majority of ITS applications. Finally, we provide a prospect of current research lines within Data Science that can bring notable advances to data-based ITS modeling, which will eventually bridge the gap towards the practicality and actionability of such models.This work was supported in part by the Basque Government for its funding support through the EMAITEK program (3KIA, ref. KK-2020/00049). It has also received funding support from the Consolidated Research Group MATHMODE (IT1294-19) granted by the Department of Education of the Basque Government

ℓ-CTP: Utilizing Multiple Agents to Find Efficient Routes in Disrupted Networks

Recent hurricane seasons have demonstrated the need for more effective methods of coping with flooding of roadways. A key complaint of logistics managers is the lack of knowledge when developing routes for vehicles attempting to navigate through areas which may be flooded. In particular, it can be difficult to re-route large vehicles upon encountering a flooded roadway. We utilize the Canadian Traveller’s Problem (CTP) to construct an online framework for utilizing multiple vehicles to discover low-cost paths through networks with failed edges unknown to one or more agents a priori. This thesis demonstrates the following results: first, we develop the ℓ-CTP framework to extend a theoretically validated set of path planning policies for a single agent in combination with the iterative penalty method, which incentivizes a group of ℓ \u3e 1 agents to explore dissimilar paths on a graph between a common origin and destination. Second, we carry out simulations on random graphs to determine the impact of the addition of agents on the path cost found. Through statistical analysis of graphs of multiple sizes, we validate our technique against prior work and demonstrate that path cost can be modeled as an exponential decay function on the number of agents. Finally, we demonstrate that our approach can scale to large graphs, and the results found on random graphs hold for a simulation of the Houston metro area during hurricane Harvey

Interleaving Allocation, Planning, and Scheduling for Heterogeneous Multi-Robot Coordination through Shared Constraints

In a wide variety of domains, such as warehouse automation, agriculture, defense, and assembly, effective coordination of heterogeneous multi-robot teams is needed to solve complex problems. Effective coordination is predicated on the ability to solve the four fundamentally intertwined questions of coordination: what (task planning), who (task allocation), when (scheduling), and how (motion planning). Owing to the complexity of these four questions and their interactions, existing approaches to multi-robot coordination have resorted to defining and solving problems that focus on a subset of the four questions. Notable examples include Task and Motion Planning (what and how), Multi-Agent Planning (what and who), and Multi-Agent Path Finding (who and how). In fact, a holistic problem formulation that fully integrates the four questions lies beyond the scope of prior literature. This dissertation focuses on examining the use of shared constraints on tasks and robots to interleave algorithms for task planning, task allocation, scheduling, and motion planning and investigating the hypothesis that a framework that interleaves algorithms to these four sub-problems will lead to solutions with lower makespans, greater computational efficiency, and the ability to solve larger problems. To support this claim, this dissertation contributes: (i) a novel temporal planner that interleaves task planning and scheduling layers, (ii) a trait-based time-extended task allocation framework that interleaves task allocation, scheduling, and motion planning, (iii) the formulation of holistic heterogeneous multi-robot coordination problem that simultaneously considers all four questions, (iv) a framework that interleaves layers for all four questions to solve this holistic heterogeneous multi-robot coordination problem, (v) a scheduling algorithm that reasons about temporal uncertainty, provides a theoretical guarantee on risk, and can be utilized within our framework, and (vi) a learning-based scheduling algorithm that reasons about deadlines and can be utilized within our framework.Ph.D

Learning a Motion Policy to Navigate Environments with Structured Uncertainty

Navigating in uncertain environments is a fundamental ability that robots must have in many applications such as moving goods in a warehouse or transporting materials in a hospital. While much work has been done on navigation that reacts to unexpected obstacles, there is a lack of research in learning to predict where obstacles may appear based on historical data and utilizing those predictions to form better plans for navigation. This may increase the efficiency of a robot that has been working in the same environment for a long period of time. This thesis first introduces the Learned Reactive Planning Problem (LRPP) that formalizes the above problem and then proposes a method to capture past obstacle information and their correlations. We introduce an algorithm that uses this information to make predictions about the environment and forms a plan for future navigation. The plan balances exploiting obstacle correlations (ie. observing obstacle A is present means obstacle B is present as well) and moving towards the goal. Our experiments in an idealized simulation show promising results of the robot outperforming a commonly used optimistic algorithm. Second, we introduce the Learn a Motion Policy (LAMP) framework that can be added to navigation stacks on real robots. This framework aims to move the problem of predicting and navigating through uncertainties from idealized simulations to realistic settings. Our simulation results in Gazebo and experiments on a real robot show that the LAMP framework has potential to improve upon existing navigation stacks as it confirms the results from the idealized simulation, while also highlighting challenges that still need to be addressed

The future of fully automated vehicles : opportunities for vehicle- and ride-sharing, with cost and emissions savings

textFully automated or autonomous vehicles (AVs) hold great promise for the future of transportation, with Google and other auto manufacturers intending on introducing self-driving cars to the public by 2020. New automation functionalities will produce dramatic transportation system changes, across safety, mobility, travel behavior, and the built environment. This work’s results indicate that AVs may save the U.S. economy up to $37.7 billion from safety, mobility and parking improvements at the 10$447.1 billion with 90% market penetration. With only 10% market share, over 1,000 lives could be saved annually. However, realizing these potential benefits while avoiding pitfalls requires overcoming significant barriers including AV costs, liability, security, privacy, and missing research. Additionally, once fully self-driving vehicles can safely and legally drive unoccupied, a new personal travel transportation mode looks set to arrive. This new mode is the shared automated vehicle (SAV), combining on-demand service features with self-driving capabilities. This work simulates a fleet of SAVs operating within Austin, Texas, first using an idealized grid-based representation, and next using Austin’s actual transportation network and travel demand flows. This second model incorporates dynamic ride-sharing (DRS), allowing two or more travelers with similar origins, destinations and departure times to share a ride. Model results indicate that each SAV could replace around 10 conventionally-owned household vehicles while serving over 56,000 person-trips. SAVs’ ability to relocate unoccupied between serving one traveler and the next may cause an increase of 7-10% more travel; however, DRS can result in reduced overall VMT, given enough SAV-using travelers willing to ride-share. Furthermore, using DRS results in overall lower wait and service times for travelers, particularly from pooling rides during peak demand. SAVs should produce favorable emissions outcomes, with an estimated 16% less energy use and 48% lower volatile organic compound (VOC) emissions, per person-trip compared to conventional vehicles. Finally, assuming SAVs cost $70,000 each, an SAV fleet in Austin could provide a 19$1 per trip-mile served. In summary, this new paradigm holds much promise that technological advances may soon realized.Civil, Architectural, and Environmental Engineerin