Biped Robots: Effects of Small Perturbations on the Generation of Modular Trajectories

Carla M.A. Pinto2 *, Diana Rocha*, Cristina P. Santos**
* Instituto Superior de Engenharia do Porto
and Centro de Matematica da Universidade do Porto
Rua Dr Antonio Bernardino de Almeida, 431,
4200-072 Porto, Portugal
** Universidade do Minho
Dept. Electronica Industrial
Campus de Azurem
4800-058 Guimaraes, Portugal
Received 29 December, 2011; accepted in revised form 19 June, 2012
Abstract: Humanoid robots have been extensively studied in the last few years. The motivation for
this study is that bipedal locomotion is superior to wheeled approaches on real terrain and situations
where robots accompany or replace humans. Some examples are, on the development of human
assisting device, such as prosthetics, orthotics, and devices for rehabilitation, rescue of wounded
troops, maidens, accompany and assistance to elderly people, amongst others. Online generation of
trajectories for these robots is a complex process, that includes different types of movements, i.e.,
distinct motor primitives. In this paper, we consider two motor primitives: rhythmic and discrete. We
study the effect on a bipeds robots’ gaits of inserting the discrete part as an offset of the rhythmic
primitive, for synaptic and diffusive couplings. We also study stability of biped gaits. We simulate a
periodic solution corresponding to the biped run, for the variation of the discrete offset. We find that
amplitude and frequency of this periodic solution, are almost constant in all cases studied. This is
useful when considering implementations of the proposed controllers for generating trajectories for
the joints of real biped robots.


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