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Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Structure of the state machine controller with all possible transitions between states. The states of pre-lift, squatting, lifting and sitting are grouped inside a superstate which allows transitions back to the walking or standing state. Arrows with circles denote initial transitions.