Title
On-line learning and modulation of periodic movements with nonlinear dynamical systems
Abstract
The paper presents a two-layered system for (1) learning and encoding a periodic signal without any knowledge on its frequency and waveform, and (2) modulating the learned periodic trajectory in response to external events. The system is used to learn periodic tasks on a humanoid HOAP-2 robot. The first layer of the system is a dynamical system responsible for extracting the fundamental frequency of the input signal, based on adaptive frequency oscillators. The second layer is a dynamical system responsible for learning of the waveform based on a built-in learning algorithm. By combining the two dynamical systems into one system we can rapidly teach new trajectories to robots without any knowledge of the frequency of the demonstration signal. The system extracts and learns only one period of the demonstration signal. Furthermore, the trajectories are robust to perturbations and can be modulated to cope with a dynamic environment. The system is computationally inexpensive, works on-line for any periodic signal, requires no additional signal processing to determine the frequency of the input signal and can be applied in parallel to multiple dimensions. Additionally, it can adapt to changes in frequency and shape, e.g. to non-stationary signals, such as hand-generated signals and human demonstrations.
Year
DOI
Venue
2009
https://doi.org/10.1007/s10514-009-9118-y
Autonomous Robots
Keywords
Field
DocType
Learning by imitation,Adaptive frequency oscillators,Dynamic movement primitives,Modulating learned trajectory
Periodic function,Computer vision,Signal processing,Fundamental frequency,Control theory,Computer science,Waveform,Modulation,Dynamical systems theory,Artificial intelligence,Periodic graph (geometry),Dynamical system
Journal
Volume
Issue
ISSN
27
1
0929-5593
Citations 
PageRank 
References 
55
2.91
31
Authors
4
Name
Order
Citations
PageRank
Andrej Gams138529.54
Auke Jan Ijspeert23546282.93
Stefan Schaal36081530.10
Jadran Lenarcic413622.94