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Walknet, a bio-inspired controller for hexapod walking.

Schilling M, Hoinville T, Schmitz J, Cruse H - Biol Cybern (2013)

Bottom Line: It has been tested by kinematic and dynamic simulations as well as on a number of six-legged robots.Walknet shows how a number of properties observed in insects may emerge from a decentralized architecture.Finally, we briefly address the ability of this decentralized reactive controller to form the basis for the simulation of higher-level cognitive faculties exceeding the capabilities of insects.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Cybernetics and Theoretical Biology, Bielefeld University, P.O. Box 100131, 33501 , Bielefeld, Germany. malteschilling@googlemail.com

ABSTRACT
Walknet comprises an artificial neural network that allows for the simulation of a considerable amount of behavioral data obtained from walking and standing stick insects. It has been tested by kinematic and dynamic simulations as well as on a number of six-legged robots. Over the years, various different expansions of this network have been provided leading to different versions of Walknet. This review summarizes the most important biological findings described by Walknet and how they can be simulated. Walknet shows how a number of properties observed in insects may emerge from a decentralized architecture. Examples are the continuum of so-called "gaits," coordination of up to 18 leg joints during stance when walking forward or backward over uneven surfaces and negotiation of curves, dealing with leg loss, as well as being able following motion trajectories without explicit precalculation. The different Walknet versions are compared to other approaches describing insect-inspired hexapod walking. Finally, we briefly address the ability of this decentralized reactive controller to form the basis for the simulation of higher-level cognitive faculties exceeding the capabilities of insects.

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Typical examples of tripod (above) and tetrapod (below) gait (redrawn after Graham 1972). Abscizza is time, black bars indicate swing movement. R1, R2, R3 right front, middle, and hind legs, respectively. L1, L2, L3: corresponding left legs
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Fig2: Typical examples of tripod (above) and tetrapod (below) gait (redrawn after Graham 1972). Abscizza is time, black bars indicate swing movement. R1, R2, R3 right front, middle, and hind legs, respectively. L1, L2, L3: corresponding left legs

Mentions: Before explaining details, some basic terminology should be introduced. On the phenomenological level, a walking leg can be characterized to be in one of two states, “swing” or “stance” (sometimes called return stroke and power stroke, respectively). During the swing movement, the leg is lifted off the ground and moved to a position where the next stance movement can be started. During a stance movement, the body is supported and moved in the desired direction. Swing and stance movements are usually characterized by two positions, defined in a body-fixed coordinate system (Bässler 1972). The posterior extreme position (PEP) is defined as the position at which the leg is lifted off the ground to start a swing movement. The anterior extreme position (AEP) defines the position where the leg switches from swing to stance by touching the ground (see Fig. 1). The cooperation of the legs results in spatio-temporal walking patterns which were, by earlier authors (e.g., Graham 1972, 1985; Hughes 1952; Wilson 1966), defined by the terms tripod gait, tetrapod gait, and wave gait (further names have been used, too). Figure 2 depicts a typical tripod pattern and a typical tetrapod pattern. Loosely defined, in tripod at least three legs, in tetrapod at least four legs, and in wave gait at least five legs are on the ground at any time (for attempts of more quantitative definitions see Wosnitza et al. 2013; Grabowska et al. 2012). Although generally used, the term “gait” may be, however, misleading as, in insects, there are no fixed patterns with instable transitions as found in walk, trot, and gallop of horses, for example (see Graham 1972, Fig. 7). Instead, there exists a continuum of phase relations between the legs.Fig. 1


Walknet, a bio-inspired controller for hexapod walking.

Schilling M, Hoinville T, Schmitz J, Cruse H - Biol Cybern (2013)

Typical examples of tripod (above) and tetrapod (below) gait (redrawn after Graham 1972). Abscizza is time, black bars indicate swing movement. R1, R2, R3 right front, middle, and hind legs, respectively. L1, L2, L3: corresponding left legs
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3755227&req=5

Fig2: Typical examples of tripod (above) and tetrapod (below) gait (redrawn after Graham 1972). Abscizza is time, black bars indicate swing movement. R1, R2, R3 right front, middle, and hind legs, respectively. L1, L2, L3: corresponding left legs
Mentions: Before explaining details, some basic terminology should be introduced. On the phenomenological level, a walking leg can be characterized to be in one of two states, “swing” or “stance” (sometimes called return stroke and power stroke, respectively). During the swing movement, the leg is lifted off the ground and moved to a position where the next stance movement can be started. During a stance movement, the body is supported and moved in the desired direction. Swing and stance movements are usually characterized by two positions, defined in a body-fixed coordinate system (Bässler 1972). The posterior extreme position (PEP) is defined as the position at which the leg is lifted off the ground to start a swing movement. The anterior extreme position (AEP) defines the position where the leg switches from swing to stance by touching the ground (see Fig. 1). The cooperation of the legs results in spatio-temporal walking patterns which were, by earlier authors (e.g., Graham 1972, 1985; Hughes 1952; Wilson 1966), defined by the terms tripod gait, tetrapod gait, and wave gait (further names have been used, too). Figure 2 depicts a typical tripod pattern and a typical tetrapod pattern. Loosely defined, in tripod at least three legs, in tetrapod at least four legs, and in wave gait at least five legs are on the ground at any time (for attempts of more quantitative definitions see Wosnitza et al. 2013; Grabowska et al. 2012). Although generally used, the term “gait” may be, however, misleading as, in insects, there are no fixed patterns with instable transitions as found in walk, trot, and gallop of horses, for example (see Graham 1972, Fig. 7). Instead, there exists a continuum of phase relations between the legs.Fig. 1

Bottom Line: It has been tested by kinematic and dynamic simulations as well as on a number of six-legged robots.Walknet shows how a number of properties observed in insects may emerge from a decentralized architecture.Finally, we briefly address the ability of this decentralized reactive controller to form the basis for the simulation of higher-level cognitive faculties exceeding the capabilities of insects.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Cybernetics and Theoretical Biology, Bielefeld University, P.O. Box 100131, 33501 , Bielefeld, Germany. malteschilling@googlemail.com

ABSTRACT
Walknet comprises an artificial neural network that allows for the simulation of a considerable amount of behavioral data obtained from walking and standing stick insects. It has been tested by kinematic and dynamic simulations as well as on a number of six-legged robots. Over the years, various different expansions of this network have been provided leading to different versions of Walknet. This review summarizes the most important biological findings described by Walknet and how they can be simulated. Walknet shows how a number of properties observed in insects may emerge from a decentralized architecture. Examples are the continuum of so-called "gaits," coordination of up to 18 leg joints during stance when walking forward or backward over uneven surfaces and negotiation of curves, dealing with leg loss, as well as being able following motion trajectories without explicit precalculation. The different Walknet versions are compared to other approaches describing insect-inspired hexapod walking. Finally, we briefly address the ability of this decentralized reactive controller to form the basis for the simulation of higher-level cognitive faculties exceeding the capabilities of insects.

Show MeSH
Related in: MedlinePlus