抄録
In many industrial applications, high performance and light position controllers for robot drives are required. To satisfy these needs, a new backlashless servomechanism using twin motors is proposed. Both twin motors are coupled with reduction gears and are controlled to generate opposite torques each other in any load for compensating the backlash error of the gears.
The motor controller consists of positioning control for one motor coupling with a position sensor and torque control for the other. For positioning control, I-PD control implemented with a position feedback and a speed feedback are employed. In the accelerating or decelerating action, both motors are controlled to generate the same direction torque to achieve the highest speed response. In the steady state, one motor is controlled to generate the opposite constant torque for compensation of the backlash errors.
In the experimental system, twin 100 WDC motors and reduction gears with the double-reduction by spur gears of the ratio of 1: 50 are employed. The two-phase rotary encoder of 500 ppr directly coupled with the motor shaft is used for sensing the position. The DC tachogenerator is also coupled with the same shaft.
The experimental results prove that the proposed system provides high precision about 13 (1/100, 000 rev.) and the weight is about 1/3 of the conventional direct drive motor.
