Servo controller

A servo controller for controlling a servomotor in accordance with a movement amount determined by a command received from a host controller in a predetermined control cycle, the servo controller comprising:

• a processor programmed to
• in a control cycle (n) in which a command cannot be received from the host controller, calculate an alternative movement amount according to
• jerk calculated with reference to amounts of movement used for controlling the servomotor in former control cycles before the control cycle (n), and
• a movement amount used for controlling the servomotor in a previous control cycle (n−1) before the control cycle (n), and
• control movement of the servomotor by use of the alternative movement amount in the control cycle (n) in which the command cannot be received from the host controller,
• wherein the processor is further programmed to
• calculate a command movement amount upper limit of a movement amount of the servomotor in each control cycle in accordance with a predetermined rate of acceleration and a movement amount used for controlling the servomotor in a previous control cycle,
• calculate a remaining movement amount based on a remainder movement amount adjusted by the processor in said each control cycle,
• output the calculated remaining movement amount in a following control cycle,
• limit, to the command movement amount upper limit, a movement amount obtained by adding the remaining movement amount to a movement amount determined by a command received from the host controller said in each control cycle so as to use the limited amount for controlling the servomotor in said each control cycle, and
• output a rest of the movement amount limited to the command movement amount upper limit as a remainder movement amount adjusted by the processor.