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Many researches have investigated the gait generations and adaptation mechanisms of animals. It is well-known that a decerebrate cat can change and adapt its gait on split-belt (velocity of left-fore belt is faster than others) treadmill. In our previous study, we showed that the leg controller as a model of CPG (Central Pattern Generator) using leg loading/unloading for the leg phase transition can integrate rhythmic motion control and posture control using a quadruped robot Kotetsu. We intend to make a physical model of split-belt adaptation of a decerebrate cat at cerebellum through experiments employing this CPG model. For such experiments, we need to construct the system keeping legs of the robot touching down on each belt. In this study, we develop the system measuring the position and orientation of the robot in the horizontal plane using a camera above the treadmill. The visual navigation system adjusts the trajectory of joints using such visual information. But adjustment of hip roll joint angle in the swing phase might conflict with touch down angle control for stable posture in the roll plane, and make the robot fall down. On the other hand, adjustment of hip roll joint angle in the stance phase is not concerned with touch angle control, does not disturb the posture in the roll plane, and makes the robot keep walking on the split-belt treadmill. As the results of experiments, we confirmed those characteristics, and realized the split-belt walking of the robot. Spec. and movies of Kotetsu can be seen at http://www.robotlocomotion.kit.ac.jp/kotetsu/index-j.html.

Nowadays, in vitro fertilization (IVF) of mammalian embryos is an essential technique in the reproductive technology and other related life science fields. However, the fertility rate by this technique is still less than 25%. Therefore, a novel in vitro fertilization method which obtains high fertility rate has been highly desired to the reproductive technology. In this study, we proposed and developed an in vitro embryo production device which allows three steps of sperm selection, fertilization and culture on a microdevice. To realize this concept, we integrated the sperm sorting function combining with swim-up and swim-down methods onto the device. To evaluate the device functions, sperm sorting experiment, in vitro fertilization experiment, and embryo culture experiment have been carried out. As results, we concluded that the device has ability to produce high quality embryos by integrating the sperm sorting function. This concept will open and enhance the management of in vitro fertilized embryos for assisted reproductive technology, livestock breeding, and fundamental stage research by further development.