Showing papers by "Jonas Buchli published in 2005"

From Dynamic Hebbian Learning for Oscillators to Adaptive Central Pattern Generators

Abstract: Note: Full paper on CD Reference BIOROB-CONF-2005-011 Record created on 2005-11-03, modified on 2017-05-10

A dynamical systems approach to learning: a frequency-adaptive hopper robot

Abstract: We present an example of the dynamical systems approach to learning and adaptation. Our goal is to explore how both control and learning can be embedded into a single dynamical system, rather than having a separation between controller and learning algorithm. First, we present our adaptive frequency Hopf oscillator, and illustrate how it can learn the frequencies of complex rhythmic input signals. Then, we present a controller based on these adaptive oscillators applied to the control of a simulated 4-degrees-of-freedom spring-mass hopper. By the appropriate design of the couplings between the adaptive oscillators and the mechanical system, the controller adapts to the mechanical properties of the hopper, in particular its resonant frequency. As a result, hopping is initiated and locomotion similar to the bound emerges. Interestingly, efficient locomotion is achieved without explicit inter-limb coupling, i.e. the only effective inter-limb coupling is established via the mechanical system and the environment. Furthermore, the self-organization process leads to forward locomotion which is optimal with respect to the velocity/power ratio.

Complexity Engineering: Harnessing Emergent Phenomena as Opportunities for Engineering

Abstract: Despite a lot of knowledge about complex systems the application of this knowledge to the en-gineering domain remains dicult. E orts are scattered over many scienti c and engineering dis-ciplines. In this contribution we would like to motivate the union of these e orts by establishingcomplexity engineering as a discipline. We will motivate this initiative and show a few aspects thatwe consider important to arrive with this goal. After a historically inspired call for uni cation ofthe eld we will present one of the most fundamental problems engineers are facing when deployingcomplex systems knowledge, what leads us to the formulation of the self-organization { speci cationtradeo principle. Then, we dicuss what we consider central ingredients to complexity engineering:i) theory, ii) universal principles, iii) implementation substrates, iv) designing, programming andcontrolling methodologies v) collecting and sharing of experience in complexity engineering.I. INTRODUCTION

Nonlinear Modelling of double and triple period pitch breaks in vocal fold vibration

Abstract: This paper reports a study on short-time subharmonic pitch breaks in vocal fold vibration, which are found to be a common feature of the human voice in spoken language. The observed pitch breaks correspond to a change in periodicity of the electrolaryngograph (Lx) signal. This paper presents a nonlinear dynamical system capable of producing time-series with subharmonic pitch breaks. The resulting time-series resemble closely Lx recordings of natural speech. The system is developed on the basis of a second order linear system, which is extended with a third dimension and nonlinear coupling terms. It is suggested that improved knowledge about pitch breaks could be used in future speech synthesis systems in order to improve the naturalness of the perceived output.

Adaptive Dynamical Systems for Movement Control

Abstract: Note: Abstract Reference BIOROB-CONF-2005-009 Record created on 2005-11-03, modified on 2017-05-10