STUDY ON SAVING ENERGY FOR MECHATRONICS USING NOLINEAR CHARACTERISTICS

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It is important to reduce the dissipated energy even for mechatronic systems such as manipulators and servo systems for improving the environment of the earth that is warmed up by CO_2 gas emitted from thermal power plants. Hence, this project has studied on optimal velocity functions and optimal gear ratios that minimize the dissipated energy in a position control system including reduction gears.The energy dissipated in the mechatronic systems is composed of Joule loss due to motor armature resistances and friction loss due to gears. First, Coulomb friction of a reduction gear is represented using efficiency of the gear and the dynamic equation is expressed. Te optimal current and velocity functions that minimize the dissipated energy are obtained from optimal control theory. For nonlinearity due to the Coulomb friction of a reduction gear, the zero crossing time is introduced in order to obtain analytical solutions. The effect of each parameter of the system on the optimal zero crossing time is investigated by simulation. Finally, an experiment on position control is performed using the optimal velocity functions. The energy dissipated with the optimal velocity function is compared to the energy dissipated with a trapezoidal velocity function. The results of the experiment and simulations indicate that the optimal velocity function can provide remarkable energy saving for a larger moment of load inertia.The dissipated energy also depends on a transmission ratio of power transmitter such as gears and ball-screws. The dissipated energy is expressed by a transmission ratio, efficiency of the transmitter and load. In order to minimize the dissipated energy, the transmission ratios of gears and ball-screws are obtained by numerically and analytically. The obtained optimal transmission ratios can reduce the dissipated energy compare to the conventional inertia matching method.