text: In principle, reinforcement learning and policy search methods can enable robots to learn highly complex and general skills that may allow them to function amid the complexity and diversity of the real world. However, training a policy that generalizes well across a wide range of real-world conditions requires far greater quantity and diversity of experience than is practical to collect with a single robot. Fortunately, it is possible for multiple robots to share their experience with one another, and thereby, learn a policy collectively. In this work, we explore distributed and asynchronous policy learning as a means to achieve generalization and improved training times on challenging, real-world manipulation tasks. We propose a distributed and asynchronous version of Guided Policy Search and use it to demonstrate collective policy learning on a vision-based door opening task using four robots. We show that it achieves better generalization, utilization, and training times than the single robot alternative.
  @cite_14: Policy search methods can allow robots to learn control policies for a wide range of tasks, but practical applications of policy search often require hand-engineered components for perception, state estimation, and low-level control. In this paper, we aim to answer the following question: does training the perception and control systems jointly end-to-end provide better performance than training each component separately? To this end, we develop a method that can be used to learn policies that map raw image observations directly to torques at the robot's motors. The policies are represented by deep convolutional neural networks (CNNs) with 92,000 parameters, and are trained using a guided policy search method, which transforms policy search into supervised learning, with supervision provided by a simple trajectory-centric reinforcement learning method. We evaluate our method on a range of real-world manipulation tasks that require close coordination between vision and control, such as screwing a cap onto a bottle, and present simulated comparisons to a range of prior policy search methods.
  @cite_4: We adapt the ideas underlying the success of Deep Q-Learning to the continuous action domain. We present an actor-critic, model-free algorithm based on the deterministic policy gradient that can operate over continuous action spaces. Using the same learning algorithm, network architecture and hyper-parameters, our algorithm robustly solves more than 20 simulated physics tasks, including classic problems such as cartpole swing-up, dexterous manipulation, legged locomotion and car driving. Our algorithm is able to find policies whose performance is competitive with those found by a planning algorithm with full access to the dynamics of the domain and its derivatives. We further demonstrate that for many of the tasks the algorithm can learn policies end-to-end: directly from raw pixel inputs.
  @cite_3: We describe an iterative procedure for optimizing policies, with guaranteed monotonic improvement. By making several approximations to the theoretically-justified procedure, we develop a practical algorithm, called Trust Region Policy Optimization (TRPO). This algorithm is similar to natural policy gradient methods and is effective for optimizing large nonlinear policies such as neural networks. Our experiments demonstrate its robust performance on a wide variety of tasks: learning simulated robotic swimming, hopping, and walking gaits; and playing Atari games using images of the screen as input. Despite its approximations that deviate from the theory, TRPO tends to give monotonic improvement, with little tuning of hyperparameters.
  @cite_19: 
  @cite_13: In this work we present a reinforcement learning system for autonomous reaching and grasping using visual servoing with a robotic arm. Control is realized in a visual feedback control loop, making it both reactive and robust to noise. The controller is learned from scratch by success or failure without adding information about the task's solution. All of the system's major components are implemented as neural networks. The system is applied to solving a combined reaching and grasping task involving uncertainty directly on a real robotic platform. Its main parts and the conditions for their successful interoperation are described. It will be shown that even with minimal prior knowledge, the system can learn in a short amount of time to reliably perform its task. Furthermore, we describe the control system's ability to react to changes and errors.
summary: Enabling robotic learning with more expressive policy classes that can represent more complex strategies has the potential of eliminating the need for the manual design of representations. Recent years have seen improvement in the generalizability of passive perception systems, in domains such as computer vision, natural language processing, and speech recognition through the use of deep learning techniques @cite_19 . These methods combine deep neural networks with large datasets to achieve remarkable results on a diverse range of real-world tasks. However, the requirement of large labeled datasets has limited the application of such methods to robotic learning problems. While several works have extended deep learning methods to simulated @cite_3 @cite_4 and real-world @cite_13 @cite_14 robotic tasks, the kind of generalization exhibited by deep learning in passive perception domains has not yet been demonstrated for robotic skill learning. This may be due to the fact that robotic learning experiments tend to use relatively small amounts of data in constrained domains, with a few hours of experience collected from a single robot in each experiment.