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Collaborating Authors

 Engin, Selim


Real-time Simultaneous Multi-Object 3D Shape Reconstruction, 6DoF Pose Estimation and Dense Grasp Prediction

arXiv.org Artificial Intelligence

Abstract-- Robotic manipulation systems operating in complex environments rely on perception systems which provide information about the geometry (pose and 3D shape) of the objects in the scene along with other semantic information such as object labels. This information is then used for choosing the feasible grasps on relevant objects. In this paper, we present a novel method to provide this geometric and semantic information of all objects in the scene as well as feasible grasps on those objects simultaneously. The main advantage of our method is its speed as it avoids sequential perception and grasp planning steps. With detailed quantitative analysis we show that our method delivers competitive performance compared to the state-of-the-art dedicated methods for object shape, pose, and grasp predictions, while providing fast inference at 30 frames per second speed.


Neural Optimal Control using Learned System Dynamics

arXiv.org Artificial Intelligence

We study the problem of generating control laws for systems with unknown dynamics. Our approach is to represent the controller and the value function with neural networks, and to train them using loss functions adapted from the Hamilton-Jacobi-Bellman (HJB) equations. In the absence of a known dynamics model, our method first learns the state transitions from data collected by interacting with the system in an offline process. The learned transition function is then integrated to the HJB equations and used to forward simulate the control signals produced by our controller in a feedback loop. In contrast to trajectory optimization methods that optimize the controller for a single initial state, our controller can generate near-optimal control signals for initial states from a large portion of the state space. Compared to recent model-based reinforcement learning algorithms, we show that our method is more sample efficient and trains faster by an order of magnitude. We demonstrate our method in a number of tasks, including the control of a quadrotor with 12 state variables.


Higher-Order Function Networks for Learning Composable 3D Object Representations

arXiv.org Machine Learning

We present a method to represent 3D objects using higher order functions, where an object is encoded directly into the weights and biases of a small `mapping' network by a larger encoder network. This mapping network can be used to reconstruct 3D objects by applying its encoded transformation to points sampled from a simple canonical space. We first demonstrate that an encoder network can produce mappings that reconstruct objects from single images more accurately than state of the art point set reconstruction methods. Next, we show that our method yields meaningful gains for robot motion planning problems that use this object representation for collision avoidance. We also demonstrate that our formulation allows for a novel method of object interpolation in a latent function space, where we compose the roots of the reconstruction functions for various objects to generate new, coherent objects. Finally, we demonstrate the coding efficiency of our approach: encoding objects directly as a neural network is highly parameter efficient when compared with object representations that encode the object of interest as a latent vector `codeword'. Our smallest reconstruction network has only about 7000 parameters and shows reconstruction quality generally better than state-of-the-art codeword-based object representation architectures with millions of parameters.