Author(s): Pieter Abbeel, Adam Coates and Andrew Y. Ng
Venue: International Journal of Robotics Research
Year Published: 2010
Keywords: learning from demonstration, optimal control, dynamical systems
Expert Opinion: The helicopter stunts achieved in this work are some of the most compelling examples in robotics of both imitation learning and reinforcement learning. (The combination of the two is called apprenticeship learning.) In this work, multiple, imperfect trajectory demonstrations are used to generate ideal trajectories, and then reinforcement learning is used to learn sequences of linear feedback controllers that reproduce those trajectories. When people say things like "but there haven't really been many successes in using reinforcement learning on *real* robots, right?" you can point to this work and say, "sure there are! Have you *seen* these crazy helicopter tricks?"

Author(s): Auke Jan Ijspeert, Jun Nakanishi, Heiko Hoffmann, Peter Pastor, Stefan Schaal
Venue: Neural Computation (Volume 25, Issue 2)
Year Published: 2013
Keywords: planning, learning from demonstration, dynamical systems, nonlinear systems
Expert Opinion: Foundation for motion planning using iterative learning methods

Author(s): Pieter Abbeel, Andrew Y. Ng
Venue: International Conference on Machine Learning
Year Published: 2004
Keywords: reinforcement learning, learning from demonstration
Expert Opinion: Provided a convincing demonstration of the usefulness of inverse reinforcement learning

Author(s): Auke Jan Ijspeert, Jun Nakanishi, Stefan Schaal
Venue: IEEE International Conference on Robotics and Automation (ICRA)
Year Published: 2002
Keywords: probabilistic models, nonlinear systems, dynamical systems, learning from demonstration, humanoid robotics
Expert Opinion: First work that proproses practical movement primitive representation for robotics. Very concise paper: shows how much can be packed into 6 pages.

Author(s): Sebastian Thrun, Wolfram Burgard, Dieter Fox
Venue: Book
Year Published: 2005
Keywords: probabilistic models
Expert Opinion: Probabilistic Robotics is a tour de force, replete with material for students and practitioners alike.

Author(s): Dean A. Pomerleau
Venue: MITP
Year Published: 1989
Keywords: mobile robots, learning from demonstration, neural networks
Expert Opinion: This work presents the first successful application of imitation learning to an autonomous system. I think this is a pivotal work in the early years of robot learning.

Author(s): Marcin Andrychowicz, Filip Wolski, Alex Ray, Jonas Schneider, Rachel Fong, Peter Welinder, Bob McGrew, Josh Tobin, Pieter Abbeel, Wojciech Zaremba
Venue: Neural Information Processing Systems Conference (NeurIPS)
Year Published: 2018
Keywords: manipulation, humanoid robotics, reinforcement learning, neural networks
Expert Opinion: A really nice, simple idea for learning parameterized skills (building on UVFAs) and efficiently dealing with sparse reward. I think Learning Parameterized Motor Skills on a Humanoid Robot (Castro Da Silva et. al) has a much better description of the parameterized skill learning problem than the HER or UVFA papers, but the HER paper has better practical ideas.

Author(s): Lerrel Pinto, Abhinav Gupta
Venue: IEEE International Conference on Robotics and Automation (ICRA)
Year Published: 2015
Keywords: manipulation, reinforcement learning, neural networks
Expert Opinion: This paper demonstrated that it's possible to have a robot interact in a self-supervised way with the environment in order to learn useful tasks, like grasping. By running a robot for a long period of time, it's possible to collect enough data to train policies using simple algorithms. This lead the way for a lot of follow up work from Google and others, and is likely an area where we'll see a lot of interest in the future.

Author(s): Ashutosh Saxena, Justin Driemeyer, Andrew Y. Ng
Venue: International Journal of Robotics Research
Year Published: 2008
Keywords: neural networks, dynamical systems, visual perception, learning from demonstration, manipulation, planning
Expert Opinion: This is one of the first works in literature that utilized machine learning for the robotic manipulation problem. The proposed framework is still useful to design similar robot learning solutions. The particular importance of this work is to identify local features that are related to manipulation planning

Author(s): Marc Peter Deisenroth, Carl Edward Rasmussen
Venue: International Conference of Machine Learning
Year Published: 2011
Keywords: state estimation, reinforcement learning, probabilistic models, gaussians, dynamical systems, visual perception, policy gradients
Expert Opinion: it is a nice answer to the problem of learning models.

Author(s): Pierre-Yves Oudeyer, Frederic Kaplan, and Verena V. Hafner
Venue: IEEE Transactions on Evolutionary Computation (Volume 11, Issue 2)
Year Published: 2007
Keywords: reinforcement learning, evolution, neural networks
Expert Opinion: This work contributes to the general question of obtaining life-long learning robotic systems. Large body of the existing robot learning literature mostly focus on methods that enable the robots to learn particular pre-defined skills and achieve particular tasks. Life-long learning, on the other hand, requires the robots to learn skills and adapt to situations that were not (and cannot be) foreseen. Inspired from human development, intrinsic motivation is an important drive that guides the robots towards regions that can be most effectively and efficiently learned with the capabilities developed so far; exploiting metrics such as novelty, curiosity, diversity, etc. This paper, in particular, is a seminal study that exploits maximization of learning progress in a real robot that explores its continuous sensorimotor space. It nicely shows that the robot exhibits stage-like development, learning easy tasks first, and focusing to more complex problems later; progressively developing more advanced skills.

Author(s): Stephane Ross, Geoffrey J. Gordon, J. Andrew Bagnell
Venue: 14th International Conference on Artificial Intelligence and Statistics
Year Published: 2011
Keywords: neural networks, learning from demonstration, dynamical systems
Expert Opinion: Introduces Data Aggregation and the general approach of viewing policy optimization as online learning. Formalizes the notion of interaction with an expert as surrogate objective to the usual policy optimization objective.

Author(s): Nate Kohl, Peter Stone
Venue: IEEE International Conference on Robotics and Automation (ICRA)
Year Published: 2004
Keywords: reinforcement learning, policy gradients, locomotion, legged robots
Expert Opinion: The work is practical in that it allowed the authors to improve the walking speed of Aibos, something essential to creating top-flight robocup players. The reason I adore this work and frequently cite it in my talks on machine learning is the fantastic way it allowed the robots to learn autonomously. In particular, for the Aibo robots to succeed in robocup, they need to be able to localize on the field based on their perception of provided markers. The authors enabled the robots to measure their own walking speed leveraging this capability. By marching a team of robots back and forth across the width of the pitch, experimenting with and evaluating different gaits each time, the robots were able to find movement patterns that surpassed hand-designed ones. It's a beautiful example of exploiting measurable quantities to drive learning---a key enabling technology for robot learning.

Author(s): Alexandros Paraschos, Christian Daniel, Jan Peters, and Gerhard Neumann
Venue: Neural Information Processing Systems Conference (NeurIPS)
Year Published: 2013
Keywords: manipulation, probabilistic models, gaussians, planning, learning from demonstration
Expert Opinion: This and the following papers using ProMPs, because they provided a very nice formulation for representing probabilistic movement primitives. ProMPs have many advantages and I found them better than classical DMPs in many robotics applications, from gestures to whole-body manipulations.

Author(s): Sergey Levine, Chelsea Finn, Trevor Darrell, Pieter Abbeel
Venue: Journal of Machine Learning Research
Year Published: 2016
Keywords: manipulation, probabilistic models, planning, locomotion, learning from demonstration, reinforcement learning, neural networks, visual perception
Expert Opinion: This was the paper which first seriously popularized robotics as a problem of interest to the deep learning community. Many of the previous papers that applied deep learning techniques to robotics tasks looked at the perception problem in isolation. This paper hinted at the fact that the entire stack, from perception to actuation, could potentially be recast as a learning problem without suffering a catastrophic degradation in sample efficiency.

Author(s): Richard S. Sutton and Andrew G. Barto
Venue: Book
Year Published: 2018
Keywords: mobile robots, reinforcement learning, unsupervised learning, optimal control, genetic algorithms
Expert Opinion: Somewhat repeating myself from the last suggestion: for learning robot behavior, reinforcement learning is an essential tool. While Sutton & Barto do not focus specifically on the case of robotics, their book is a very accessible text that nevertheless manages to cover many aspects, techniques, and challenges in reinforcement learning.

Author(s): Marc Peter Deisenroth, Gerhard Neumann, Jan Peters
Venue: Book
Year Published: 2013
Keywords: survey, reinforcement learning
Expert Opinion: A great unifying view on policy search

Author(s): Peter Pastor, Heiko Hoffmann, Tamim Asfour, and Stefan Schaal
Venue: IEEE International Conference on Robotics and Automation (ICRA)
Year Published: 2009
Keywords: planning, learning from demonstration
Expert Opinion: DMPs (Dynamic Movement Primitives) are a good representation for learning robot movements from demonstration, as well as for doing reinforcement learning based on demonstrations. This paper explains a variant of the original DMP formulation that makes them stable when generalizing movements to accommodate new goals, or obstacles in the robot's path. It then shows how the new DMPs can be used for one-shot learning of tasks such as pick-and-place operations or water serving. More robust than just a trajectory, and less complex than learning with many trials, this is a nice tool to have in your robot learning toolkit.

Author(s): Brian D. Ziebart, Andrew Maas, J.Andrew Bagnell, and Anind K. Dey
Venue: AAAI Conference on Artificial Intelligence
Year Published: 2008
Keywords: probabilistic models, learning from demonstration, reinforcement learning
Expert Opinion: This work is one of the first to connect probabilistic inference with robot policy learning. Maximum Entropy Inverse Reinforcement Learning poses the classical Inverse Reinforcement Learning problem, well-studied for several years before this work, as maximizing the likelihood of observing a state distributing given a noisily optimal agent w.r.t an unknown reward function. The inference method, model, and general principles not only inspired future IRL works (such as RelEnt-IRL, GP-IRL, and Guided Cost Learning), they also have been applied in Human Robot Interaction and general policy search algorithms.

Author(s): George Konidaris, Leslie Pack Kaelbling, Tomas Lozano-Perez
Venue: Journal of Artificial Intelligence Research
Year Published: 2018
Keywords: probabilistic models, planning
Expert Opinion: As we get better at low-level robotic control, the community will need to start thinking more about longer-horizon problems and how to smoothly flow between reasoning at different levels of abstraction. This paper presents a theoretically-ground formal treatment of the problem, proves some nice stuff about what constitutes necessary and sufficient symbols for various types of planning, and shows some nice demos on a real robot. It is by far the best analysis of hierarchical learning / planning that I know of and provides a much-needed theoretical foundation for moving this area of research forward.