The present disclosure relates to a critical point locking method of servos, including: computing a current target deviation according to a target position and an actual position, computing a variation value according to the current target deviation and a previous target deviation, determining whether the variation value being greater than a constraint value, modifying the current target deviation according to the current target deviation and a predetermined value upon determining the predetermined condition being satisfied, configuring the modified current target deviation as a current controlling deviation, and driving the servo to move toward the target position according the current controlling deviation. As such, the servo may lock the position for 360 degrees, the locking stroke of the servo may be improved, and the application of the servo may be enlarged.

A servo control device including a servo control unit that calculates a drive command that causes a feedback position from a motor to be driven to follow a command position, to drive the motor according to the drive command, a moving-state determination unit that determines a speed of the motor is by simulating a response of the motor, and outputs a determination result as a moving state, a correction-amount selection unit that selects a correction amount according to a change pattern of the moving state at a timing when the determined moving state changes, and an addition unit that adds the correction amount output from the correction-amount selection unit to the drive command calculated by the servo control unit to generate a corrected drive command, and sets the corrected drive command as a drive command to the motor instead of the drive command calculated by the servo control unit.

The present disclosure relates to a critical point locking method of servos, including: computing a current target deviation according to a target position and an actual position, computing a variation value according to the current target deviation and a previous target deviation, determining whether the variation value being greater than a constraint value, modifying the current target deviation according to the current target deviation and a predetermined value upon determining the predetermined condition being satisfied, configuring the modified current target deviation as a current controlling deviation, and driving the servo to move toward the target position according the current controlling deviation. As such, the servo may lock the position for 360 degrees, the locking stroke of the servo may be improved, and the application of the servo may be enlarged.

A tailstock control device includes a tailstock parameter setting unit that receives, in advance, setting of tailstock acceleration time ta, tailstock movement velocity V, drive torque measuring period t, and number n of drive torque measurements; a calculating unit that calculates acceleration zone distance La from the acceleration time ta and the movement velocity V; a calculating unit that calculates constant velocity zone distance Lb from the movement velocity V, the measuring period t, and the number n of measurements; a drive torque detecting unit that detects servo motor drive torque; and a control unit that sets La+Lb as drive torque measuring distance Lt and calculates servo motor drive torque limit value c from drive torque T detected by the drive torque detecting unit when the tailstock is moved over La+Lb and also from a servo motor torque command value a required for supporting a workpiece.