Controller and extrapolation method of command value

An extrapolation method in a controller which receives a command value to a motor for each axis from a host apparatus and updates the command value to be used in a predetermined updating period to servo-control the motor based on the command value, the extrapolation method comprising:

• when the command value in a “t”-th updating period which is used for servo-control is defined as y(t), calculating a command value y(k) which is used in a “k”-th updating period according to a following expression when the command value from the host apparatus is not received or abnormality occurs in the communication in the “k”-th updating period:
• y(k)=y(k−2)+{y(k−1)−y(k−3)}, or
• y(k)=y(k−2)+{y(k−2)−y(k−4)}.

An extrapolation method in a controller which receives a command value to a motor for each axis from a host apparatus and updates the command value to be used in a predetermined updating period to servo-control the motor based on the command value, the extrapolation method comprising:

• when “m” is an integer of two or more, and a transmission period for transmitting the command value by the host apparatus is “m”-times of the updating period, and the command value in a “t”-th updating period which is used in the control part is defined as y(t),
• calculating a command value y(k) which is used in a “k”-th updating period according to a following expression when the command value from the host apparatus is not received or abnormality occurs in the communication in the “k”-th updating period:
• y(k)=y(k−m)+{y(k−1)−y(k−m−1)}.