Learning-Based Real-Time Torque Prediction for Grasping Unknown Objects with a Multi-Fingered Hand

When grasping objects with a multi-finger hand, it is crucial for the grasp stability to apply the correct torques at each joint so that external forces are countered. Most current systems use simple heuristics instead of modeling the required torque correctly. Instead, we propose a learning-based approach that is able to predict torques for grasps on unknown objects in real-time. The neural network, trained end-to-end using supervised learning, is shown to predict torques that are more efficient, and the objects are held with less involuntary movement compared to all tested heuristic baselines. Specifically, for 90 % of the grasps the translational deviation of the object is below 2.9 mm and the rotational below 3.1°. To generate training data, we formulate the analytical computation of torques as an optimization problem and handle the indeterminacy of multi-contacts using an elastic model. We further show that the network generalizes to predict torques for unknown objects on the real robot system with an inference time of 1.5 ms. Website: dlr-alr.github.io/grasping/