Next Article in Journal
Reliable Real-Time Ball Tracking for Robot Table Tennis
Next Article in Special Issue
Control of the Sit-To-Stand Transfer of a Biped Robotic Device for Postural Rehabilitation
Previous Article in Journal
Questionnaires to Measure Acceptability of Social Robots: A Critical Review
Previous Article in Special Issue
Analysis of the Compliance Properties of an Industrial Robot with the Mozzi Axis Approach
Open AccessArticle

Estimation and Closed-Loop Control of COG/ZMP in Biped Devices Blending CoP Measures and Kinematic Information

by Giuseppe Menga 1,*,† and Marco Ghirardi 2,†
1
Department of Control and Computer Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy
2
Department of Management and Production Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy
*
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Robotics 2019, 8(4), 89; https://doi.org/10.3390/robotics8040089
Received: 17 July 2019 / Revised: 15 October 2019 / Accepted: 16 October 2019 / Published: 22 October 2019
(This article belongs to the Special Issue Advances in Italian Robotics)
The zero moment point ( Z M P ) and the linearized inverted pendulum model linking the Z M P to the center of gravity ( C O G ) have an important role in the control of the postural equilibrium (balance) of biped robots and lower-limb exoskeletons. A solution for balance real time control, closing the loop from the joint actual values of the C O G and Z M P , has been proposed by Choi. However, this approach cannot be practically implemented: While the Z M P actual value is available from the center of pressure ( C o P ) measured under the feet soles, the C O G is not measurable, but it can only be indirectly assessed from the joint-angle measures, the knowledge of the kinematics, and the usually poorly known weight distribution of the links of the chain. Finally, the possible presence of unknown external disturbance forces and the nonlinear, complex nature of the kinematics perturb the simple relationship between the Z M P and C O G in the linearized model. The aim of this paper is to offer, starting from Choi’s model, a practical implementation of closed-loop balance control fusing C o P and joint-angle measures, eliminating possible inconsistencies. In order to achieve this result, we introduce a model of the linearized inverted pendulum for an extended estimation, not only of C O G and Z M P , but also of external disturbances. This model is then used, instead of Choi’s equations, for estimation and balance control, using H theory. As the C O G information is recovered from the joint-angle measures, the identification of a statistically equivalent serial chain ( S E S C ) linking the C O G to the joint angles is also discussed. View Full-Text
Keywords: biped robotics; exoskeletons; postural equilibrium; zero moment point; inverted pendulum; robust control biped robotics; exoskeletons; postural equilibrium; zero moment point; inverted pendulum; robust control
Show Figures

Figure 1

MDPI and ACS Style

Menga, G.; Ghirardi, M. Estimation and Closed-Loop Control of COG/ZMP in Biped Devices Blending CoP Measures and Kinematic Information. Robotics 2019, 8, 89.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop