A comprehensive study on the dynamics of dissolved elements (Mg, Al, Si, P, Ca, V, Cr, Mn, Fe, Ni, Zn, As, Sr, Y, W, and U) in Lake Biwa was carried out using a clean technique. Lake water samples (n ϭ 523) were collected from six stations in the North Basin and three stations in the South Basin. River water samples (n ϭ 178) were collected from 14 major rivers flowing into the North Basin. Rainwater samples (n ϭ 89) were collected at Otsu. The river water was enriched with Mn, Al, Fe, P, and Zn and the rainwater was enriched with Zn, Al, Fe, and Mn compared to North Basin water during winter mixing. The residence times of dissolved species were estimated on the basis of input through the rivers and rain. The residence times for Ca, Mg, and Sr were about 8 years, the same as that for water. Mn, Al, Fe, and Zn showed the shortest residence times (0.05-0.19 year). A budget calculation suggested that more than 60% of the input of dissolved Si, P, V, Cr, Mn, Fe, Ni, and Zn was scavenged and retained in the lake sediments and/or discharged as suspended particles.

Recently, extensive studies have focused on realizing novel mobility technologies, with special consideration for the aging society. The primary aim of these studies is to establish autonomous driving technology (ADT). Mainly, the objects of ADT are four-wheel motor vehicles, and new technologies are investigated from various viewpoints such as vehicle development and infrastructure improvements. However, ADT for motorcycles has received scant attention. In Japan, the motorcycle mortality rate is approximately quadruple that of four-wheel motor vehicles. Therefore, the design of autonomous motorcycles has become imperative. Furthermore, among the various operation conditions, the low-speed driving mode is the most unstable mode for motorcycles. Thus, autonomously standing up from the parking mode and stability for low-speed driving are very important subjects that should be explored under ADT. To fill this gap, some conventional studies have explored the incorporation of gyro mechanisms (Ouchi, et al., 2015) or counterweights and guide rail in motorcycles (Satoh and Namerikawa, 2006). However, these additional mechanisms often make the motorcycles bigger and heavier. In 2017, Yamaha Motor Co., Ltd. released MOTOROiD, a motorcycle with self-stabilizing mechanism (Tsuchiya, et al., 2018) (Fig. 1). MOTOROiD has a novel rotary axis, active mass center control system, (AMCES, Fig. 2), and can vary the position of the total center of gravity. For this mechanism, Yamaha designed a control system using the combination of a minor loop proportional-integral-derivative (PID)

This study discusses autonomous standing up from the parking mode and ensuring stability for low-speed driving of a novel motorcycle, named “MOTOROiD”. In 2017, Yamaha Motor Co., Ltd. released a motorcycle with a self-stabilizing mechanism, “MOTOROiD.” This prototype has a new rotary axis and can vary the position of the total center of gravity. This axis is called AMCES (Active Mass CEnter control System). This paper shows the modeling of MOTOROiD with parameters uncertainties for the control system design. The modeling is performed based on two different methods for established model verification: Lagrange’s equation method and the multibody dynamics. By using the established model, a unified control method for standing up from the parking mode and ensuring stability is designed by using a two-degree-of-freedom control system structure. The effectiveness of the modeling and control system design to the system with the variable parameter is verified by numerical simulations.

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