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A biological feedback control system with electronic input: the artificially closed femur-tibia control system of stick insects
Ist Teil von
Journal of experimental biology, 1986, Vol.120 (1), p.369-385
Ort / Verlag
Cambridge: Company of Biologists
Erscheinungsjahr
1986
Link zum Volltext
Quelle
EZB Electronic Journals Library
Beschreibungen/Notizen
ABSTRACT
An experimental arrangement was constructed which is based on the open-loop femurtibia control system of two stick insect species (Carausius morosus and Cuniculina impigra). It could be artificially closed in the following way: the position of the tibia was measured by an optical device and this value was used to drive a penmotor which moved the receptor apodeme of the femoral chordotonal organ in the same way as in intact animals. This arrangement allows direct comparison of the behaviour of the open-loop and the closed-loop system as well as introducing an additional delay.
The Carausius system has a phase reserve of only 30° –50° and the factor of feedback control approaches 1 between 1 and 2 Hz. This agrees with the observation that an additional delay of 70–200 ms produces long-lasting oscillations of 1–2 Hz. The Cuniculina system has a larger phase reserve and consequently a delay of 200 ms produced no oscillations. All experiments show that extrapolation from the open-loop system to the closed-loop system is valid, despite the non-linear characteristics of the loop. Consequences for servo-mechanisms during walking and rocking movements are discussed.