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Estimation of a multifingered gripper joint configuration using 3D point clouds and AI

Examples of robotic gripping with three multifingered grippers: Shadow (five fingers), Allegro (four fingers), and Barrett (three fingers). Crédit : CEA
In robotic gripping, the positions of the effectors (phalanges or fingertips) on an object must be controlled precisely. Knowledge of the joints’ internal configurations is essential to achieving this. We looked at a practical case where the only information available was a 3D point cloud of the gripper, generated by visual sensors, simulations, or generative neural networks.

Conventional inverse kinematics (IK) techniques can provide mathematically exact solutions (if any exist) for determining joint configuration from effector (fingertip) position alone. However, because the positions of gripper fingers’ intermediate phalanges must also be considered, these techniques often require a posteriori decision-making. For more complex kinematics, numerical approximation algorithms, which may not perform as well in dynamic environments, are used.

 


Figure 1. Using this method, we were able to find the joint configuration from a complete or partial 3D point cloud of a multifingered robotic gripper. Credit : CEA

We developed an innovative machine learning method that leverages a conditional variational autoencoder (CVAE) to reconstruct joint configurations from the robotic gripper’s point cloud.

 


Figure 2. Data used: Complete or partial point clouds.

Tests on the MultiDex dataset produced an average joint error of less than 4% with ultra-rapid inference (< 0.05 ms). The algorithm, whose ultra-rapid inference eliminates the need for computationally-costly numerical optimization steps, responds to the demands of real-time environments. Because the training data is generated solely from the URDF model, the method is easy to adapt to any type of gripper.

Key figure

4%

average joint error with inference time of 0.05 ms (faster than the state of the art) with the MultiDex grip dataset and the Allegro gripper.

Learn more

Flagship publication

  • « Leveraging CVAE for Joint Configuration Estimation of Multifingered Grippers from Point Cloud Data », J. Mérand, B. Meden and M. Grossard, 2025 IEEE 21st International Conference on Automation Science and Engineering (CASE), Los Angeles, CA, USA, 2025, pp. 895-900, https://doi.org/10.48550/arXiv.2511.17276

 

Contributor to this article:

  • Julien Mérand, PhD student, CEA-List
  • Boris Meden, Research Engineer, CEA-List
  • Mathieu Grossard, Research Director and Senior Expert, CEA-List