Akihiko Imagi

State and parameter estimation for step motors under actual working conditions

A method of measuring the dynamic behavior and characteristics of step motors without attaching mechanical sensors is described. Friction load torque and motor torque constant, as well as rotor position and velocity, are estimated by a sequential least square filter driven by sensed back electromotive force and current. The validity of the proposed filter is confirmed in detail by comparing the estimated results with direct measurements in both steady and transient state.<<ETX>>

Control-system development of a high-speed electromagnetic actuator in consideration of the delay in the control force

A control system for a high-speed electromagnetic actuator contains the problems of electromagnetic nonlinearity, a rising current lag, and a lag in the control force caused by an eddy current. In this paper, we conduct a simulation and a control experiment that take those influences into account. Our results confirmed the effectiveness of the control method, which provides compensation for the nonlinearity of the control force, the rising current lag and the control force lag.

Vibration suppression control for electrical discharge machine by using relative displacement and velocity feed back

In order to suppress the instability in a fully-closed-loop of the positioning servo, we proposed a new controller which feeds back the relative displacement and the relative velocity from the motor to the positioning table. A stability condition is investigated in the 2-DOF model that is the basis of the fully-closed-loop system, and the precise effect of the controller is examined in a 4-DOF model of an actual electrical discharge machine. Operation of an actual machining test clarifies the effectiveness of the proposed controller.