Study of postural adjustments for humanoidal helpmates

Humanoid robots and humans look alike, and therefore are expected to adjust their posture in a similar way. We analysed a set of human static postures that should be considered for humanoids acting as caretakers. A dynamic situation was studied to learn how humanoids can react in a dynamical way. Human data were obtained with a professional motion capture system and anthropometric tables. The static postures were studied using a segmented human body model, but for motion analysis the single and double pendulums with moving masses were also employed. For robot motion synthesis we need to know the relation between the posture and the postural stability. We have shown that the positions of mass centres of the pendulum segments (which match the human body point masses) are crucial for postural stabilization. The Zero-Moment Point criterion was applied for the dynamic case. The static analysis demonstrates that there are some common features of the postures. The dynamic analysis indicated that both pendulums are good models of human body motion, and are useful for humanoid motion synthesis. In humanoids, it is easier to apply results represented by inverted pendulums than postural models represented by stick diagrams. This is because humanoids and humans do not obviously share the same mass distribution and sizes (proportions) of all body segments. Moreover our descriptions indicate where to locate the supporting leg/legs in single and double support, which in general, is missing in inverted pendulum models discussed in the literature. The paper’s aim is to deepen the knowledge about the adjustment of human postures for the purpose of robotics.

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Opracowanie ze środków MNiSW w ramach umowy 812/P-DUN/2016 na działalność upowszechniającą naukę (zadania 2017).