tailieunhanh - Adaptive Motion of Animals and Machines - Hiroshi Kimura et al (Eds) Part 2

Tham khảo tài liệu 'adaptive motion of animals and machines - hiroshi kimura et al (eds) part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 12 Reinhard Blickhan et al. Fig. 5. Two segment model to investigate stability. velocity Fig. 6. Phaseplots for a stable left and an unstable right situation. dashed line undisturbed fat line disturbed Robust Behaviour of the Human Leg 13 Robust control In highly dynamic situations such as running and jumping the delays within the spinal and cortical reflex loops do not allow fine tuned action during the short contact times. These events are largely steered by feed forward control. This requires robust behaviour of the leg as described in the preceding sections. If the leg behaves robust and does not break down in a catastrophic event during ground contact control and corrections are possible step by step. Using the simplest model of a bouncing system the spring-mass-system we investigated the suitability of neuronal networks for control 18 19 . Desired speed and angle of attack at next touch down served as input parameters the take off angles where asked for as output and fed back into the network. It turned out that Multi-Layer-Perceptrons consisting of 7 and 9 neurons in two hidden layers were able to steer such a conservative system to any velocity and along any path . Even though the system learned only to run at various velocities it was able to cover rough ground . to correct on a step by step basis by adapting the angle of attack. A quite limited number of very simple neurons is sufficient to control such a dynamic behaviour as long as the system properties remain simple and robust. Conservative behaviour of the human leg The human leg has to fulfil many different tasks such as static support during standing in a hammer like action during a kick or as a compliant axial strut during running. We investigate to which extent control and properties of the human leg are adapted to certain loading regimes by exposing it to artificial loading situations. An instrumented inclined track allows axial hopping like loading under reduced gravity and with