This is the first study of a real physical kneed bipedal robot that exhibits passive dynamic running (PDR). Passive dynamic walking (PDW), which has its roots in the pioneering research of McGeer, intrinsically offers not only nonlinear phenomena such as the pull-in effect and perioddoubling bifurcation, but also offers an extremely interesting phenomenon that facilitates the engineering of a highly efficient walking robot. In recent years, a wide variety of verification experiments in PDW were performed using actual devices. In contrast, however, very few studies addressed PDR. In the present study, we developed a two-dimensional real physical passive dynamic running biped with knees. The device stands 400 mm tall and weights 4.8 kg. By carefully designing the properties of the elastic elements implemented into the hip joints and the stance legs in the present device, we achieved stable passive dynamic running of 36 steps. The device runs at about 0.83 m/s down a 0.22 rad slope. To the best of our knowledge, this is a first report of such a performance. This result is expected to prove useful not only for designing human-like natural and efficient bipedal robots, but also for understanding the principles underlying bipedal locomotion.
CP-propeller is known to have the following disadvantages compared with FF-propeller.
1) Increased risk of root cavitation due to the restricted blade width at the root.
2) Parts with an increased number of notches are required to function under fluctuating loads in the un-uniform stern stream.
In order to solve these problems, we conducted 1) blade stress measurements with real ships, 2) static loading tests with model propellers, 3) blade bolt fatigue tests, and 4) propeller cavitation tests, and on the basis of the data obtained through these tests we worked out a new blade suspension system suited for large CPPs, which we named "semi-integrated trunnion" and, have put to practical use successfully. We have also demonstrated that with adoption of this semi-integrated trunnion the upper limit for the severity index for CPP design set by KHI on the basis of the past records can be raised substantially.
The authors' company has had long and extensive experience with controliable-pitch (CP) propellers and marine geared diesel plants. In 1974, on the basis of this experience, the company built the world's largest CP propeller [46 000 hp (34 300 kW)]. This paper describes the design features of the propeller, its operating experience, the reasons for adopting a CP propeller, and the historical background of the merchant ship in which the propeller was installed.
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