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With the increasing complexity of humanoid mechanisms and their desired capabilities, there is a pressing need for a generalized framework where a desired whole-body motion behavior can be easily specified and controlled. Our hypothesis is that human motion results from simultaneously performing multiple objectives in a hierarchical manner, and we have analogously developed a prioritized, multiple-task control framework. The operational space formulation 10 provides dynamic models at the task level and structures for decoupled task and posture control. 13 This formulation allows for posture objectives to be controlled without dynamically interfering with the operational task. Achieving higher performance of posture objectives requires precise models of their dynamic behaviors. In this paper we complete the picture of task descriptions and whole-body dynamic control by establishing models of the dynamic behavior of secondary task objectives within the posture space. Using these models, we present a whole-body control framework that decouples the interaction between the task and postural objectives and compensates for the dynamics in their respective spaces.

[1] Using the equatorial electrojet (EEJ) peak current intensity as deduced from CHAMP magnetic observations from the years 2001 through 2009, we investigated the relationship between sudden stratospheric warming (SSW) and lunitidal signatures in the tropical ionosphere. There is a practically one-to-one correspondence between midwinter SSW periods and the strongest 13 day modulation of the EEJ strength as observed by CHAMP. That is, all the midwinter SSW periods from December 2001 to August 2009 were accompanied by an enhanced 13 day modulation of the EEJ strength. No other geophysical phenomenon brought about as strong a 13 day modulation as those of the midwinter SSW periods. During each midwinter SSW period the amplified 13 day modulation of the EEJ strengths starts roughly within AE1 week around the first peak in stratospheric temperature difference. An oscillation with a period of 13.26 days is predicted by the lunitidal equation when considering the precession of the CHAMP orbit. When fitting the lunitidal equation to the EEJ modulations during the midwinter SSW periods, consistent phase delays of 4.4 AE 0.3 days of the tidal signal emerge for all the cases. The results suggest that the pronounced 13 day modulation of the EEJ strength is related to an enhancement of the lunar tide in the ionosphere by the SSW effect.

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