Search

PurposeA lot of unique transportation devices on the ground have been developed. On the other hand, on water, there are a few personal devices, which sometimes need paddling to get around. If the personal mobility that make it possible to move intuitively and quickly on water is realized, it will be useful for survey of rivers and ponds, rescue, amusement and so on. Therefore, in this study, an omnidirectional vehicle on water (O‐VOW) is proposed which is controlled according to information of the inclination based on a rider's balance.Design/methodology/approachA prototype of O‐VOW consists of a boarding part, three thrusters and a control unit. The control unit includes a three‐axes accelerometer, a microcomputer and batteries. The inclination of O‐VOW is calculated from the information given by the accelerometer. The control rule for O‐VOW is described in matrix form and is implemented into the microcomputer. The microcomputer commands three thrusters according to the inclination. The preliminary and riding tests are conducted on water.FindingsThe authors have developed a prototype of O‐VOW whose propulsion is controlled according to the inclination. The control scheme for O‐VOW was described in matrix form. The preliminary and riding tests are conducted on water and the effectiveness of O‐VOW was experimentally shown. O‐VOW can run, stop and adjust the course in all directions on water by the rider's balance.Originality/valueIn this paper, a novel transportation system that uses intuitive control on water has been developed. Since it moves in all directions, the rider can operate it even at a narrow channel without turning. It will assist in human activities such as survey, rescue, amusement in rivers, lakes, swimming pools and at sea.

Most industrial robots are driven through reduction gear units by DC or AC servomotors. The elasticity of the drive systems including these reduction gear units cannot be ignored when the high-speed and precise motion control is required for robots. Due to the elasticity of the drive systems, the vibratory behaviors are caused, and the control performances of robot systems are deteriorated. In this study, we develop a new actuator, which consists of an AC servomotor, a harmonic drive gear and an ER damper. Since the gap between electrodes of the ER damper is 80 [Rm], only the voltage of 80 [V] is needed for the electric field of 1 [kV/mm]. And this ER damper consumes little electric power. The actuator is installed to the one-link robot arm. The mathematical model of the robot arm is derived, and the eigenvalues of the robot system are analyzed. The experiments are conducted, and the effectiveness of the actuator is shown.