Recognizing point clouds using conditional random fields

Detecting objects in cluttered scenes is a necessary step for many robotic tasks and facilitates the interaction of the robot with its environment. Because of the availability of efficient 3D sensing devices as the Kinect, methods for the recognition of objects in 3D point clouds have gained importance during the last years. In this paper, we propose a new supervised learning approach for the recognition of objects from 3D point clouds using Conditional Random Fields, a type of discriminative, undirected probabilistic graphical model. The various features and contextual relations of the objects are described by the potential functions in the graph. Our method allows for learning and inference from unorganized point clouds of arbitrary sizes and shows significant benefit in terms of computational speed during prediction when compared to a state-of-the-art approach based on constrained optimization.Peer ReviewedPostprint (author’s final draft

Vision-based Robotic Grasping in Simulation using Deep Reinforcement Learning

This thesis will investigate different robotic manipulation and grasping approaches. It will present an overview of robotic simulation environments, and offer an evaluation of PyBullet, CoppeliaSim, and Gazebo, comparing various features. The thesis further presents a background for current approaches to robotic manipulation and grasping by describing how the robotic movement and grasping can be organized. State-of-the-Art approaches for learning robotic grasping, both using supervised methods and reinforcement learning methods are presented. Two set of experiments will be conducted in PyBullet, illustrating how Deep Reinforcement Learning methods could be applied to train a 7 degrees of freedom robotic arm to grasp objects

A Proposed Priority Pushing and Grasping Strategy Based on an Improved Actor-Critic Algorithm

The most basic and primary skills of a robot are pushing and grasping. In cluttered scenes, push to make room for arms and fingers to grasp objects. We propose a modified Actor-Critic (A-C) framework for deep reinforcement learning, Cross-entropy Softmax A-C (CSAC), and use the Prioritized Experience Replay (PER) based on the theoretical foundation and main methods of deep reinforcement learning, combining the advantages of algorithms based on value functions and policy gradients. The grasping model is trained using self-supervised learning to achieve end-to-end mapping from image to propulsion and grasping action. A vision module and an action module have been created out of the entire algorithm framework. The prioritized experience replay is improved to further improve the CSAC-PER algorithm for model sample diversity and robot exploration performance during robot grasping training. The experience replay buffer is dynamically sampled using the prior beta distribution and the dynamic sampling algorithm based on the beta distribution (CSAC-beta) is proposed based on the CSAC algorithm. Despite its low initial efficiency, the experimental simulation results show that the CSAC-beta algorithm eventually achieves good results and has a higher grasping success rate (90%)