Robots can generalize manipulation skills between different scenarios by adapting to the features of the objects being manipulated. Selecting the set of relevant features for generalizing skills has usually been performed manually by a human. Alternatively, a robot can learn to select relevant features autonomously. However, feature selection usually requires a large amount of training data, which would require many demonstrations. In order to learn the relevant features more efficiently, we propose using a meta-level prior to transfer the relevance of features from previously learned skills. The experiments show that the meta-level prior more than doubles the average precision and recall of the feature selection when compared to a standard uniform prior. The proposed approach was used to learn a variety of manipulation skills, including pushing, cutting, and pouring.
@cite_35: 
@cite_38: This paper proposes a novel 3D scene interpretation approach for robots in mobile manipulation scenarios using a set of 3D point features (Fast Point Feature Histograms) and probabilistic graphical methods (Conditional Random Fields). Our system uses real time stereo with textured light to obtain dense depth maps in the robot's manipulators working space. For the purposes of manipulation, we want to interpret the planar supporting surfaces of the scene, recognize and segment the object classes into their primitive parts in 6 degrees of freedom (6DOF) so that the robot knows what it is attempting to use and where it may be handled. The scene interpretation algorithm uses a two-layer classification scheme: i) we estimate Fast Point Feature Histograms (FPFH) as local 3D point features to segment the objects of interest into geometric primitives; and ii) we learn and categorize object classes using a novel Global Fast Point Feature Histogram (GFPFH) scheme which uses the previously estimated primitives at each point. To show the validity of our approach, we analyze the proposed system for the problem of recognizing the object class of 20 objects in 500 table settings scenarios. Our algorithm identifies the planar surfaces, decomposes the scene and objects into geometric primitives with 98.27 accuracy and uses the geometric primitives to identify the object's class with an accuracy of 96.69 .
@cite_22: Planning realizable and stable grasps on 3D objects is crucial for many robotics applications, but grasp planners often ignore the relative sizes of the robotic hand and the object being grasped or do not account for physical joint and positioning limitations. We present a grasp planner that can consider the full range of parameters of a real hand and an arbitrary object, including physical and material properties as well as environmental obstacles and forces, and produce an output grasp that can be immediately executed. We do this by decomposing a 3D model into a superquadric 'decomposition tree' which we use to prune the intractably large space of possible grasps into a subspace that is likely to contain many good grasps. This subspace can be sampled and evaluated in GraspIt!, our 3D grasping simulator, to find a set of highly stable grasps, all of which are physically realizable. We show grasp results on various models using a Barrett hand.
@cite_7: We propose a novel method for a robot to separate and segment objects in a cluttered tabletop environment. The method leverages the fact that external object boundaries produce visible edges within an object cluster. We achieve this singulation of objects by using the robot arm to perform pushing actions specifically selected to test whether particular visible edges correspond to object boundaries. We verify the separation of objects after a push by examining the clusters formed by geometric segmentation of regions residing on the table surface. To avoid explicitly representing and tracking edges across push behaviors we aggregate over all edges in a given orientation by representing the push-history as an orientation histogram. By tracking the history of directions pushed for each object cluster we can build evidence that a cluster cannot be further separated. We present quantitative and qualitative experimental results performed in a real home environment by a mobile manipulator using input from an RGB-D camera mounted on the robot's head. We show that our pushing strategy can more reliably obtain singulation in fewer pushes than an approach, that does not explicitly reason about boundary information.
@cite_48: The idea that connected convex surfaces, separated by concave boundaries, play an important role for the perception of objects and their decomposition into parts has been discussed for a long time. Based on this idea, we present a new bottom-up approach for the segmentation of 3D point clouds into object parts. The algorithm approximates a scene using an adjacency-graph of spatially connected surface patches. Edges in the graph are then classified as either convex or concave using a novel, strictly local criterion. Region growing is employed to identify locally convex connected subgraphs, which represent the object parts. We show quantitatively that our algorithm, although conceptually easy to graph and fast to compute, produces results that are comparable to far more complex stateof-the-art methods which use classification, learning and model fitting. This suggests that convexity concavity is a powerful feature for object partitioning using 3D data. Furthermore we demonstrate that for many objects a natural decomposition into “handle and body” emerges when employing our method. We exploit this property in a robotic application enabling a robot to automatically grasp objects by their handles.
@cite_1: For robot to perform its tasks competently, robustly and in the right context it has to understand the course of its actions and their consequences. For example, imagine the robot being tasked with the clean up of the breakfast table. The robot is confronted with a heavily cluttered scene and has to be able to tell waste, dirty, clean and valuable objects apart. The robot shall be equipped with the knowledge that will, for instance, stop it from throwing away an expensive item. Herein proposed approach elevates robot’s perception skills in that it utilizes its capabilities to interact with the clutter of objects. This allows for better segmentation and finally also better object recognition by means of constraining the recognition to a region or regions of interest. Similar to [1] and [2], we propose a system that uses a robot arm to induce motions in a scene to enable effective object segmentation. Our system employs a combination of the following techniques: i) estimation of a contact point and a push direction of the robot’s end effector by detecting the concave corners in the cluttered scene, ii) feature extraction using features proposed by Shi and Tomasi and tracking using optical flow, and iii) a novel clustering algorithm to segment the objects. Segmentation of rigid objects from a video stream of objects being moved by the robot has been addressed by Fitzpatrick [3] and [4]. In contrast, our arm motion is not pre-planned but adapts to the scene, we make use of the 3D data to segment the object candidates from the background and we use a novel clustering approach for the segmentation of textured objects. Overview of the whole system is shown in Fig. 2. The system will be demostrated live during the workshop.
@cite_11: Most objects are composed of parts which have a semantic meaning. Ahandle can have many different shapes and can be present in quite different objects, but there is only one semantic meaning to a handle, which is "a part that is designed especially to be grasped by the hand". We introduce here a novel 3D algorithm named CPS for the decomposition of objects into their semantically meaningful parts. These meaningful parts are learned from experiments where robot grasps different objects. Objects are represented in compositional graph hierarchy where their parts are represented as the relationship between subparts, which are in turn represented based on the relationships between small adjacent regions. Unlike other compositional approaches, our method relies on learning semantically meaningful parts which are learned from grasping experience. This compositional part representation provides generalization for part segmentation. We evaluated our method in this respect, by training ion one dataset and evaluating it on another. We achieved on average78 part overlap accuracy for segmentation of novel part instances.
Our feature generation process is based on decomposing objects into parts. The segmentation is guided by the demonstrations of the skill. Several other works have also used actions in order to improve segmentation performance @cite_7 @cite_35 @cite_1 . However, most of these methods focus on segmenting scenes into objects rather than parts. Decomposing objects into parts has largely been based on geometric features, such as convexity @cite_38 @cite_48 @cite_22 . recently proposed a method for segmenting objects into parts based on where it could be grasped by the robot @cite_11 . Their approach uses an initial over-segmentation of an object model into supervoxels and merges these supervoxels into parts.