A gamelan, which is a percussion instrument made of bronze from the island of Bali, can be used to play various sounds by changing the shape and size, etc. Of these instruments, the keyboard percussion instrument called Gangsa can create a targeted sound by changing the shape of the sound bar, but the shape parameters do not take into consideration the impact on the sound. In this study, it is thought that the sound emitted by the sound bar originates in an inherent vibration characteristic, and thus the relationship between the shape of the sound bar and the fundamental frequency was examined. In addition, based on the results, sound bars that produce the targeted sounds were designed and produced. The study showed that the impact of the cross-sectional shape on the basic frequency of the sound bar is strong, and thus a characteristic not found in other keyboard percussion instruments is exhibited. In addition, by assuming the fundamental frequency for both end free beams and primary mode, it was possible to design the sound bar from the targeted sound. As a shape characteristic, it was confirmed that a trapezoid cross-sectional shape results in excellent balance that contributes to improved frequency at a limited weight, and the curvature had minimal impact on the fundamental frequency.

When using robots to investigate a disaster site after an earthquake, the act of carrying robots into the workplace is dangerous for the rescuer and may result in a second accident. If robots can be thrown into the workplace, operators will be safe and the job made easier. We have been researching and developing our legged robots "QRoSS" series, which are transformable robots with a spherical outer shell to absorb the external shock of landing. The purpose of this study is the development of QRoSS III, which can get over obstacles by jumping. It performs two takeoff postures and two static gaits using three legs and its shell. This paper reports concepts and the design of QRoSS III and discusses experimental results: takeoff postures, gait locomotion and a series of the jumping motions.

Rolling bearing produces an eruption of vibration owing to its own rotation. When such rolling bearings were set in a mechanical system, external vibration arising from another rotating shaft and load variation works on the rolling bearings. In past days and under such running circumstances, lifetime calculation for rolling bearing had been made by multiplying a load factor, which was influenced by the working situation of the mechanical system, to dynamic equivalent load of the bearing. However, the load factor is grouped under three values and quantitative condition to select one value out of three values is not described. A designer for the mechanical system intends to over-estimate the load factor for safety. This tendency will cause an excess specification, cost increase and growing in machine size. In the previous paper, with considering a mechanical vibration of automobile and factory automation (FA) equipment, several endurance tests were performed by applying radial vibrations having a frequency of 24.75Hz and vibration acceleration up to 10m/s². As a result, abnormal increase of vibration were not observed for up to three times of basic dynamic life. In this paper, endurance tests for more stringent condition (up to 49.5Hz and 15m/s²) than the previous ones were performed and the influence of external vibration to increase of vibration of the bearing itself was studied. As a consequence, it was clarified that the wear at the load area of outer ring became larger when the applied external vibration increased, and the external vibration had an influence on the damage of the bearing. Although flaking is not observed, it is not required to set a mechanical coefficient such as the load factor larger than 1, under the condition of this research.

Stabilizing objective function against noise factors is one of the important design activity. In this paper, we propose the new control design method, which is combining the cluster analysis with causality search T-method （CS-T） which was established in 2015. In the case where there is noise factor of non-continuous and multiple levels, this new design method is effective. This new design method consists of 4 steps; cluster analysis, CS-T experiments, calculating the estimation value for control design, and confirmation experiments. We applied this new control design method to the development of precision paper handling module, and confirmed that proposing design method enable to reduce the time to spent on design dramatically maintaining the stability of objective function.

Vehicles are used to transport people and goods efficiently. In order to move smoothly, even in an environment with limited space or numerous obstacles, the vehicle that can not only move in the longitudinal direction and turn but also move in the lateral direction is required. In order to satisfy this requirement, wheel mechanisms for lateral movement, such as the active omni wheel (AOW), which is a wheel that is movable in an arbitrary direction actively, have been proposed. However, these wheel mechanisms require numerous motors to construct a vehicle, which leads to increased size, weight, and manufacturing cost of the vehicle. In order to address this problem, the present study proposes a drive mechanism for driving AOWs by a small number of motors using switchable clutches. Vehicles equipped with this drive mechanism can move in the longitudinal and lateral directions and turn by just one or two motors. In the present paper, the structure and motion of the proposed drive mechanism are explained. Through the kinematic analysis, the establishment condition is derived. Based on the results, several structures of vehicles equipped with the proposed mechanism are introduced. Experiments are conducted using the developed vehicle, and the effectiveness of the proposed mechanism is verified.