DartBot: Overhand Throwing of Deformable Objects with Tactile Sensing and Reinforcement Learning.

*Authors of Equal Contribution
1Purdue University 2Hong Kong University of Science and Technology 3Great Bay University
Paper Accepted to IEEE T-ASE 2025
Dart in air demonstration

DartBot: Framework that integrates tactile exploration and reinforcement learning to achieve robust throwing skills for nonrigid objects.

Abstract

Object transfer through throwing is a classic dynamic manipulation task that necessitates precise control and perception capabilities. However, developing dynamic models for unstructured environments using analytical methods presents challenges.

In this study, we present DartBot, a robot that integrates tactile exploration and reinforcement learning to achieve robust throwing skills for nonrigid objects under the influence of moment of inertia which cause the object to spin in the air. Unlike traditional sim-to-real transfer methods, our approach involves direct training of the agent on a real hardware robot equipped with a high-resolution tactile sensor, enabling reinforced learning in a realistic and dynamic environment.

By leveraging tactile perception, we incorporate pseudo-embeddings of the physical properties of objects into the learning process through tilting actions at two distinct angles. This tactile information enables the agent to infer and adapt its throwing strategy, resulting in improved accuracy when handling various objects and targeting distant locations. Furthermore, we demonstrate that the quality of a grasp significantly impacts the success rate of the throwing task. We evaluate the effectiveness of our method through extensive experiments, demonstrating superior performance and generalization capabilities in real-world throwing scenarios. We achieved a success rate of 95% for unseen objects with a mean error of 3.15 cm from the goal.

Video

Experiment Objects

Using DartBot you can train nonrigid deformable objects to hit a a far away target. To generate a diverse range of objects with distinct physical properties, we employed small steel balls showcased in the top row, along with 3D printed plastic discs featured in the middle row where black disc has thickness

Darts Image

Experiment Setup

The experimental setup consisted of a UR5e robot arm, a customized parallel gripper equipped with a GelSight Mini sensor, and a magnetic dartboard. The recycling system consisted of a four-bar linkage mechanism, a guideway, and a reorientation system to facilitate autonomous training process without human involvement.

Experiment Setup Image

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