A Model-based Hierarchical Controller for Legged Systems subject to External Disturbances

Guiyang Xin, Hsiu-Chin Lin, Joshua Smith, Oguzhan Cebe, Michael Mistry

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Legged robots have many potential applications in real-world scenarios where the tasks are too dangerous for humans, and compliance is needed to protect the system against external disturbances and impacts. In this paper, we propose a model-based controller for hierarchical tasks of legged systems subject to external disturbance. The control framework is based on projected inverse dynamics controller, such that the control law is decomposed into two orthogonal subspaces, i.e., the constrained and the unconstrained subspaces. The unconstrained component controls multiple desired tasks with impedance responses. The constrained space controller maintains the contact subject to unknown external disturbances, without the use of any force/torque sensing at the contact points. By explicitly modelling the external force, our controller is robust to external disturbances and errors arising from incorrect dynamic model information. The main contributions of this paper include (1) incorporating an impedance controller to control external disturbances and allow impedance shaping to adjust the behaviour of the motion under external disturbances, (2) optimising contact forces within the constrained subspace that also takes into account the external disturbances without using force/torque sensors at the contact locations. The techniques are evaluated on the ANYmal quadruped platform under a variety of scenarios.
Original languageEnglish
Title of host publication2018 IEEE International Conference on Robotics and Automation (ICRA)
Subtitle of host publication Brisbane, Australia
PublisherInstitute of Electrical and Electronics Engineers (IEEE)
Number of pages8
ISBN (Electronic)978-1-5386-3081-5
ISBN (Print)978-1-5386-3082-2
Publication statusE-pub ahead of print - 13 Sep 2018
Event2018 IEEE International Conference on Robotics and Automation - The Brisbane Convention & Exhibition Venue, Brisbane, Australia
Duration: 21 May 201825 May 2018

Publication series

ISSN (Electronic)2577-087X


Conference2018 IEEE International Conference on Robotics and Automation
Abbreviated titleICRA2018
Internet address


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