85 research outputs found
Strongly extreme points and approximation properties
We show that if is a strongly extreme point of a bounded closed convex
subset of a Banach space and the identity has a geometrically and topologically
good enough local approximation at , then is already a denting point. It
turns out that such an approximation of the identity exists at any strongly
extreme point of the unit ball of a Banach space with the unconditional compact
approximation property. We also prove that every Banach space with a Schauder
basis can be equivalently renormed to satisfy the sufficient conditions
mentioned. In contrast to the above results we also construct a non-symmetric
norm on for which all points on the unit sphere are strongly extreme, but
none of these points are denting.Comment: 14 page
Evolved embodied phase coordination enables robust quadruped robot locomotion
Overcoming robotics challenges in the real world requires resilient control
systems capable of handling a multitude of environments and unforeseen events.
Evolutionary optimization using simulations is a promising way to automatically
design such control systems, however, if the disparity between simulation and
the real world becomes too large, the optimization process may result in
dysfunctional real-world behaviors. In this paper, we address this challenge by
considering embodied phase coordination in the evolutionary optimization of a
quadruped robot controller based on central pattern generators. With this
method, leg phases, and indirectly also inter-leg coordination, are influenced
by sensor feedback.By comparing two very similar control systems we gain
insight into how the sensory feedback approach affects the evolved parameters
of the control system, and how the performances differs in simulation, in
transferal to the real world, and to different real-world environments. We show
that evolution enables the design of a control system with embodied phase
coordination which is more complex than previously seen approaches, and that
this system is capable of controlling a real-world multi-jointed quadruped
robot.The approach reduces the performance discrepancy between simulation and
the real world, and displays robustness towards new environments.Comment: 9 page
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