Hybrid Servoing: Reliable Manipulation under External Contacts (Project Page)





Human manipulation dexterity benefits a lot from utilizing external contacts. However, it is still hard for a robot to safely and reliably use external contacts. A small error or disturbance in the system can cause the robot to crash, or the desired contact mode to break.

We believe a proper use of compliant control is the key to success. Being compliant (using force control) in suitable directions could avoid over-constraining and maintain desired contacts. Being rigid (velocity/position control) in other directions can keep the disturbance rejection ability for executing the motion plan.


Manipulation with Suction Cups using External Contacts
Xianyi Cheng, Yifan Hou and Matthew T. Mason
2019 International Symposium on Robotics Research (ISRR)
Paper · Video


Criteria for Maintaining Desired Contacts for Quasi-Static Systems
Yifan Hou and Matthew T. Mason
In Proceedings of 2019 International Conference on Intelligent Robots and Systems (IROS)
Paper


Robust Execution of Contact-Rich Motion Plans by Hybrid Force-Velocity Control
Yifan Hou and Matthew T. Mason
In Proceedings of 2019 IEEE International Conference on Robotics and Automation (ICRA)
Paper · Video



Reorienting Objects of Any Shapes between Any 3D Poses (Project Page)




We consider the problem of reorienting a rigid object with arbitrary known shape on a table using a two-finger pinch gripper. Reorienting problem is challenging because of its non-smoothness and high dimensionality. In this work, we focus on solving reorienting using pivoting, in which we allow the grasped object to rotate between fingers. Pivoting decouples the gripper rotation from the object motion, making it possible to reorient an object under strict robot workspace constraints.


Fast Planning for 3D Any-Pose-Re-orienting using Pivoting
Yifan Hou , Zhenzhong Jia and Matthew T. Mason
In Proceedings of 2018 IEEE International Conference on Robotics and Automation (ICRA)
Paper · Video


Reorienting Objects in 3D Space Using Pivoting
Yifan Hou , Zhenzhong Jia and Matthew T. Mason
(Under Review)
Paper · Video



Planar Pivoting Regrasping with Inertial Force




We investigate the planar dynamic pivoting problem, in which a pinched object is reoriented to a desired pose through wrist swing motion and grip force regulation. Traditional approaches based on friction compensation do not work well for this problem, as we observe the torsional friction at the contact has large uncertainties during pivoting. In addition, the discontinuities of friction and the lower bound constraint on the grip force all make dynamic pivoting a challenging task for robots. To address these problems, we propose a robust control strategy that directly uses friction as a key input for dynamic pivoting, and show that active friction control by regulating the grip force significantly improves system stability.


Robust Planar Dynamic Pivoting by Regulating Inertial and Grip Forces
Yifan Hou
Master’s Thesis, Robotics Institute, Carnegie Mellon University, May, 2017
Paper


Robust Planar Dynamic Pivoting by Regulating Inertial and Grip Forces
Yifan Hou , Zhenzhong Jia and Matthew T. Mason
2016, The 12th International Workshop on the Algorithmic Foundations of Robotics (WAFR)
Paper · Video



Closed-loop Pushing on Unknown Planar Surface




We propose a framework for performing single contact point planar pushing with unknown pressure distribution. The problem is challenging due to the stochastic and under-actuated system properties. Using as few as two data points, our method can estimate the control-related model parameters. To achieve posture stabilization, we use differential dynamic programming and re-plan with updated model when large deviation occurs. We demonstrate empirical success in posture stabilization and robustness with respect to different pressure distributions.


Pushing revisited: Differential flatness, trajectory planning, and stabilization
Jiaji Zhou, Yifan Hou and Matthew T. Mason
The International Journal of Robotics Research, October 2019
Paper