Lars Berscheid

dblp:165/2776 · DBLP profile ↗
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6ranked-venue papers
4as first author
4since 2021 · last 2023
0000-0003-1129-8407ORCID · corroborated

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Artificial intelligence and machine learning · 6 · 4 first-author · 4 since 2021Systems, architecture and hardware · 6 · 4 first-author · 4 since 2021
YearPublicationVenuePosition
2023 Safe Self-Supervised Learning in Real of Visuo-Tactile Feedback Policies for Industrial Insertion
abstract
Industrial insertion tasks are often performed repetitively with parts that are subject to tight tolerances and prone to breakage. Learning an industrial insertion policy in real is challenging as the collision between the parts and the environment can cause slippage or breakage of the part. In this paper, we present a safe self-supervised method to learn a visuo-tactile insertion policy that is robust to grasp pose variations. The method reduces human input and collisions between the part and the receptacle. The method divides the insertion task into two phases. In the first align phase, a tactile-based grasp pose estimation model is learned to align the insertion part with the receptacle. In the second insert phase, a vision-based policy is learned to guide the part into the receptacle. The robot uses force-torque sensing to achieve a safe self-supervised data collection pipeline. Physical experiments on the USB insertion task from the NIST Assembly Taskboard suggest that the resulting policies can achieve 45/45 insertion successes on 45 different initial grasp poses, improving on two baselines: (1) a behavior cloning agent trained on 50 human insertion demonstrations (1/45) and (2) an online RL policy (TD3) trained in real (0/45).
Letian Fu, Lars Berscheid, Kenneth Y. Goldberg, Sachin Chitta
ICRA3
2022 SpeedFolding: Learning Efficient Bimanual Folding of Garments
abstract
Folding garments reliably and efficiently is a long standing challenge in robotic manipulation due to the complex dynamics and high dimensional configuration space of garments. An intuitive approach is to initially manipulate the garment to a canonical smooth configuration before folding. In this work, we develop SpeedFolding, a reliable and efficient bimanual system, which given user-defined instructions as folding lines, manipulates an initially crumpled garment to (1) a smoothed and (2) a folded configuration. Our primary contribution is a novel neural network architecture that is able to predict pairs of gripper poses to parameterize a diverse set of bimanual action primitives. After learning from 4300 human- annotated and self-supervised actions, the robot is able to fold garments from a random initial configuration in under 120 s on average with a success rate of 93 %. Real-world experiments show that the system is able to generalize to unseen garments of different color, shape, and stiffness. While prior work achieved 3–6 Folds Per Hour (FPH), SpeedFolding achieves 30–40 FPH. See https://pantor.github.io/speedfolding for code, videos, and datasets.
Yahav Avigal, Lars Berscheid, Tamim Asfour, Torsten Kröger, Kenneth Y. Goldberg
IROS2
2021 Robot Learning of 6 DoF Grasping using Model-based Adaptive Primitives
abstract
Robot learning is often simplified to planar manipulation due to its data consumption. Then, a common approach is to use a fully-convolutional neural network (FCNN) to estimate the reward of grasp primitives. In this work, we extend this approach by parametrizing the two remaining, lateral degrees of freedom (DoFs) of the primitives. We apply this principle to the task of 6 DoF bin picking: We introduce a model-based controller to calculate angles that avoid collisions, maximize the grasp quality while keeping the uncertainty small. As the controller is integrated into the training, our hybrid approach is able to learn about and exploit the model-based controller. After real-world training of 27 000 grasp attempts, the robot is able to grasp known objects with a success rate of over 92 % in dense clutter. Grasp inference takes less than 50 ms. In further real-world experiments, we evaluate grasp rates in a range of scenarios including its ability to generalize to unknown objects. We show that the system is able to avoid collisions, enabling grasps that would not be possible without primitive adaption.
Lars Berscheid, Christian Friedrich, Torsten Kröger
ICRA1
2021 Learning a Generative Transition Model for Uncertainty-Aware Robotic Manipulation
abstract
Robot learning of real-world manipulation tasks remains challenging and time consuming, even though actions are often simplified by single-step manipulation primitives. In order to compensate the removed time dependency, we additionally learn an image-to-image transition model that is able to predict a next state including its uncertainty. We apply this approach to bin picking, the task of emptying a bin using grasping as well as pre-grasping manipulation as fast as possible. The transition model is trained with up to 42 000 pairs of real-world images before and after a manipulation action. Our approach enables two important skills: First, for applications with flange-mounted cameras, picks per hours (PPH) can be increased by around 15 % by skipping image measurements. Second, we use the model to plan action sequences ahead of time and optimize time-dependent rewards, e.g. to minimize the number of actions required to empty the bin. We evaluate both improvements with real-robot experiments and achieve over 700 PPH in the YCB Box and Blocks Test.
Lars Berscheid, Pascal Meissner, Torsten Kröger
IROS1
2019 Improving Data Efficiency of Self-supervised Learning for Robotic Grasping
abstract
Given the task of learning robotic grasping solely based on a depth camera input and gripper force feedback, we derive a learning algorithm from an applied point of view to significantly reduce the amount of required training data. Major improvements in time and data efficiency are achieved by: Firstly, we exploit the geometric consistency between the undistorted depth images and the task space. Using a relative small, fully-convolutional neural network, we predict grasp and gripper parameters with great advantages in training as well as inference performance. Secondly, motivated by the small random grasp success rate of around 3 %, the grasp space was explored in a systematic manner. The final system was learned with 23 000 grasp attempts in around 60 h, improving current solutions by an order of magnitude. For typical bin picking scenarios, we measured a grasp success rate of (96.6 ± 1.0) %. Further experiments showed that the system is able to generalize and transfer knowledge to novel objects and environments.
Lars Berscheid, Thomas Rühr, Torsten Kröger
ICRA1
2019 Robot Learning of Shifting Objects for Grasping in Cluttered Environments
abstract
Robotic grasping in cluttered environments is often infeasible due to obstacles preventing possible grasps. Then, pre-grasping manipulation like shifting or pushing an object becomes necessary. We developed an algorithm that can learn, in addition to grasping, to shift objects in such a way that their grasp probability increases. Our research contribution is threefold: First, we present an algorithm for learning the optimal pose of manipulation primitives like clamping or shifting. Second, we learn non-prehensible actions that explicitly increase the grasping probability. Making one skill (shifting) directly dependent on another (grasping) removes the need of sparse rewards, leading to more data-efficient learning. Third, we apply a real-world solution to the industrial task of bin picking, resulting in the ability to empty bins completely. The system is trained in a self-supervised manner with around 25 000 grasp and 2500 shift actions. Our robot is able to grasp and file objects with 274±3 picks per hour. Furthermore, we demonstrate the system's ability to generalize to novel objects.
Lars Berscheid, Pascal Meissner, Torsten Kröger
IROS1