Planning & Scheduling
OctoPath: An OcTree Based Self-Supervised Learning Approach to Local Trajectory Planning for Mobile Robots
Trasnea, Bogdan, Ginerica, Cosmin, Zaha, Mihai, Macesanu, Gigel, Pozna, Claudiu, Grigorescu, Sorin
Autonomous mobile robots are usually faced with challenging situations when driving in complex environments. Namely, they have to recognize the static and dynamic obstacles, plan the driving path and execute their motion. For addressing the issue of perception and path planning, in this paper, we introduce OctoPath , which is an encoder-decoder deep neural network, trained in a self-supervised manner to predict the local optimal trajectory for the ego-vehicle. Using the discretization provided by a 3D octree environment model, our approach reformulates trajectory prediction as a classification problem with a configurable resolution. During training, OctoPath minimizes the error between the predicted and the manually driven trajectories in a given training dataset. This allows us to avoid the pitfall of regression-based trajectory estimation, in which there is an infinite state space for the output trajectory points. Environment sensing is performed using a 40-channel mechanical LiDAR sensor, fused with an inertial measurement unit and wheels odometry for state estimation. The experiments are performed both in simulation and real-life, using our own developed GridSim simulator and RovisLab's Autonomous Mobile Test Unit platform. We evaluate the predictions of OctoPath in different driving scenarios, both indoor and outdoor, while benchmarking our system against a baseline hybrid A-Star algorithm and a regression-based supervised learning method, as well as against a CNN learning-based optimal path planning method.
Simplified Belief-Dependent Reward MCTS Planning with Guaranteed Tree Consistency
Sztyglic, Ori, Zhitnikov, Andrey, Indelman, Vadim
Partially Observable Markov Decision Processes (POMDPs) are notoriously hard to solve. Most advanced state-of-the-art online solvers leverage ideas of Monte Carlo Tree Search (MCTS). These solvers rapidly converge to the most promising branches of the belief tree, avoiding the suboptimal sections. Most of these algorithms are designed to utilize straightforward access to the state reward and assume the belief-dependent reward is nothing but expectation over the state reward. Thus, they are inapplicable to a more general and essential setting of belief-dependent rewards. One example of such reward is differential entropy approximated using a set of weighted particles of the belief. Such an information-theoretic reward introduces a significant computational burden. In this paper, we embed the paradigm of simplification into the MCTS algorithm. In particular, we present Simplified Information-Theoretic Particle Filter Tree (SITH-PFT), a novel variant to the MCTS algorithm that considers information-theoretic rewards but avoids the need to calculate them completely. We replace the costly calculation of information-theoretic rewards with adaptive upper and lower bounds. These bounds are easy to calculate and tightened only by the demand of our algorithm. Crucially, we guarantee precisely the same belief tree and solution that would be obtained by MCTS, which explicitly calculates the original information-theoretic rewards. Our approach is general; namely, any converging to the reward bounds can be easily plugged-in to achieve substantial speedup without any loss in performance.
Learning Neuro-Symbolic Relational Transition Models for Bilevel Planning
Chitnis, Rohan, Silver, Tom, Tenenbaum, Joshua B., Lozano-Perez, Tomas, Kaelbling, Leslie Pack
Despite recent, independent progress in model-based reinforcement learning and integrated symbolic-geometric robotic planning, synthesizing these techniques remains challenging because of their disparate assumptions and strengths. In this work, we take a step toward bridging this gap with Neuro-Symbolic Relational Transition Models (NSRTs), a novel class of transition models that are data-efficient to learn, compatible with powerful robotic planning methods, and generalizable over objects. NSRTs have both symbolic and neural components, enabling a bilevel planning scheme where symbolic AI planning in an outer loop guides continuous planning with neural models in an inner loop. Experiments in four robotic planning domains show that NSRTs can be learned after only tens or hundreds of training episodes, and then used for fast planning in new tasks that require up to 60 actions to reach the goal and involve many more objects than were seen during training.
How is AI Changing the Market Research Industry? - The AI Journal
Market research has used statistical methods to analyse people's opinions for many decades. These long-lived data sets and research methodologies have made the industry reluctant to change, as consistency is vital to the proposition. However, market research must change as people's lives and behaviours change: becoming more digital, more spontaneous and always-on, more glued to mobile phones, and competing for attention with social media and mobile games. The pandemic has only accelerated these disruptive trends as face-to-face contact became impossible and people's day-to-day behaviour drastically changed. Building AI models is one way of rapidly adjusting to this new world, as they can address the collection, verification and analysis of digital data.
Actions You Can Handle: Dependent Types for AI Plans
Hill, Alasdair, Komendantskaya, Ekaterina, Daggitt, Matthew L., Petrick, Ronald P. A.
Verification of AI is a challenge that has engineering, algorithmic and programming language components. For example, AI planners are deployed to model actions of autonomous agents. They comprise a number of searching algorithms that, given a set of specified properties, find a sequence of actions that satisfy these properties. Although AI planners are mature tools from the algorithmic and engineering points of view, they have limitations as programming languages. Decidable and efficient automated search entails restrictions on the syntax of the language, prohibiting use of higher-order properties or recursion. This paper proposes a methodology for embedding plans produced by AI planners into dependently-typed language Agda, which enables users to reason about and verify more general and abstract properties of plans, and also provides a more holistic programming language infrastructure for modelling plan execution.
Learning First-Order Representations for Planning from Black-Box States: New Results
Rodriguez, Ivan D., Bonet, Blai, Romero, Javier, Geffner, Hector
Recently Bonet and Geffner have shown that first-order representations for planning domains can be learned from the structure of the state space without any prior knowledge about the action schemas or domain predicates. For this, the learning problem is formulated as the search for a simplest first-order domain description D that along with information about instances I_i (number of objects and initial state) determine state space graphs G(P_i) that match the observed state graphs G_i where P_i = (D, I_i). The search is cast and solved approximately by means of a SAT solver that is called over a large family of propositional theories that differ just in the parameters encoding the possible number of action schemas and domain predicates, their arities, and the number of objects. In this work, we push the limits of these learners by moving to an answer set programming (ASP) encoding using the CLINGO system. The new encodings are more transparent and concise, extending the range of possible models while facilitating their exploration. We show that the domains introduced by Bonet and Geffner can be solved more efficiently in the new approach, often optimally, and furthermore, that the approach can be easily extended to handle partial information about the state graphs as well as noise that prevents some states from being distinguished.
Efficient Temporal Piecewise-Linear Numeric Planning with Lazy Consistency Checking
Bajada, Josef, Fox, Maria, Long, Derek
State-of-the-art temporal planners that support continuous numeric effects typically interweave search with scheduling to ensure temporal consistency. If such effects are linear, this process often makes use of Linear Programming (LP) to model the relationship between temporal constraints and conditions on numeric fluents that are subject to duration-dependent effects. While very effective on benchmark domains, this approach does not scale well when solving real-world problems that require long plans. We propose a set of techniques that allow the planner to compute LP consistency checks lazily where possible, significantly reducing the computation time required, thus allowing the planner to solve larger problem instances within an acceptable time-frame. We also propose an algorithm to perform duration-dependent goal checking more selectively. Furthermore, we propose an LP formulation with a smaller footprint that removes linearity restrictions on discrete effects applied within segments of the plan where a numeric fluent is not duration dependent. The effectiveness of these techniques is demonstrated on domains that use a mix of discrete and continuous effects, which is typical of real-world planning problems. The resultant planner is not only more efficient, but outperforms most state-of-the-art temporal-numeric and hybrid planners, in terms of both coverage and scalability.
Control of mental representations in human planning
Ho, Mark K., Abel, David, Correa, Carlos G., Littman, Michael L., Cohen, Jonathan D., Griffiths, Thomas L.
One of the most striking features of human cognition is the capacity to plan. Two aspects of human planning stand out: its efficiency, even in complex environments, and its flexibility, even in changing environments. Efficiency is especially impressive because directly computing an optimal plan is intractable, even for modestly complex tasks, and yet people successfully solve myriad everyday problems despite limited cognitive resources. Standard accounts in psychology, economics, and artificial intelligence have suggested this is because people have a mental representation of a task and then use heuristics to plan in that representation. However, this approach generally assumes that mental representations are fixed. Here, we propose that mental representations can be controlled and that this provides opportunities to adaptively simplify problems so they can be more easily reasoned about -- a process we refer to as construal. We construct a formal model of this process and, in a series of large, pre-registered behavioral experiments, show both that construal is subject to online cognitive control and that people form value-guided construals that optimally balance the complexity of a representation and its utility for planning and acting. These results demonstrate how strategically perceiving and conceiving problems facilitates the effective use of limited cognitive resources.
SpaceX charts a path for Starship's first orbital test flight
Following the successful landing of SN15, SpaceX now plans to attempt to fly a Starship prototype into orbit. In a filing with the Federal Communications Commission (FCC), the company details how it hopes its next test flight will unfold. According to the document, a Starship craft fitted with a Super Heavy booster will lift from the company's Boca Chica, Texas launch facility. Approximately three minutes into the flight, the booster stage will separate and splash down in the Gulf of Mexico about 20 miles from shore. The Starship rocket will pass over the Straits of Florida before entering orbit and then returning to Earth and attempting to make a soft ocean landing approximately 62 miles off the northwest coast of Kauai.
Sen. Marsha Blackburn: Biden can end our border crisis. My plan will kick start the solution
Sen. Marsha Blackburn, R-Tenn., on introducing legislation aimed at increasing national security. During his first press conference as president, Joe Biden claimed that border officials were "sending back the vast majority of the families" arriving at our southern border. Unfortunately, as every outlet that covered the issue has since reported, Biden's statement has proven false. Before he took the oath of office, then-candidate Biden was on the campaign trail promising amnesty and open borders. Now, Biden's refusal to enforce the law is allowing thousands of migrants to cross the border illegally every day, even as overworked Customs and Border Patrol agents collect, transport, and process thousands more.