This paper focuses on the problem of learning 6-DOF grasping with a parallel jaw gripper in simulation. Our key idea is constraining and regularizing grasping interaction learning through 3D geometry prediction. We introduce a deep geometry-aware grasping network (DGGN) that decomposes the learning into two steps. First, we learn to build mental geometry-aware representation by reconstructing the scene (i.e., 3D occupancy grid) from RGBD input via generative 3D shape modeling. Second, we learn to predict grasping outcome with its internal geometry-aware representation. The learned outcome prediction model is used to sequentially propose grasping solutions via analysis-by-synthesis optimization. Our contributions are fourfold: (1) To best of our knowledge, we are presenting for the first time a method to learn a 6-DOF grasping net from RGBD input; (2) We build a grasping dataset from demonstrations in virtual reality with rich sensory and interaction annotations. This dataset includes 101 everyday objects spread across 7 categories, additionally, we propose a data augmentation strategy for effective learning; (3) We demonstrate that the learned geometry-aware representation leads to about 10% relative performance improvement over the baseline CNN on grasping objects from our dataset. (4) We further demonstrate that the model generalizes to novel viewpoints and object instances.

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Link prediction is a promising research area for modeling various types of networks and has mainly focused on predicting missing links. Link prediction methods may be valuable for describing brain connectivity, as it changes in Alzheimer’s disease (AD) and its precursor, mild cognitive impairment (MCI). Here, we analyzed 3-tesla whole-brain diffusion-weighted images from 202 participants in the Alzheimer’s Disease Neuroimaging Initiative (ADNI) – 50 healthy controls, 72 with earlyMCI (eMCI) and 38 with lateMCI (lMCI) and 42 AD patients. We introduce a novel approach for Mixed Link Prediction (MLP) to test and define the percent of predictability of each heightened stage of dementia from its previous, less impaired stage, in the simplest case. Using well-known link prediction algorithms as the core of MLP, we propose a new approach that predicts stages of cognitive impairment by simultaneously adding and removing links in the brain networks of elderly individuals. We found that the optimal algorithm, called “Adamic and Adar”, had the best fit and most accurately predicted the stages of AD from their previous stage. When compared to the other link prediction algorithms, that mainly only predict the added links, our proposed approach can more inclusively simulate the brain changes during disease by both adding and removing links of the network. Our results are also in line with computational neuroimaging and clinical findings and can be improved for better results.

Successful execution of many robotic tasks requires precise control of robot motion and its interaction with the environment. In robotics these two problems are mainly studied separately in the domain of robot motion generation and interaction control, respectively. Existing approaches rely on two control loops: a motion generator (planner) that provides a reference trajectory in the outer loop, and an active impedance controller that tracks the reference trajectory in the inner loop. Ensuring stability of the closed-loop system for this control architecture is nontrivial. In this paper, we propose a single-loop control architecture that performs motion generation and interaction control at once. We model robot discrete motions with a time-invariant dynamical system, which is expressed as a nonlinear combination of a set of linear spring-damper systems. This formulation represents the nominal motion and the impedance properties with a single set of parameters, simplifying stability analysis of the closed-loop system. We provide sufficient conditions to ensure global asymptotic stability of this system for movements in free-space, and its passivity during persistent contact with a passive environment. We validate our approach in simulation using the 7-DoF KUKA LWR-IV robot.