Move command correction method and servo control system with correction of move command

A servo control system in which a move command is corrected, comprising:

• a numerical control device to issue a move command;
• a servo motor having a position/speed detector to drive a driven body;
• a servo amplifier having a current detector to control said servo motor;
• a position/speed/current control circuit to control said servo amplifier by finding a speed command from a positional deviation representing a difference between a position feedback outputted from the position/speed detector of said servo motor and a move command from said numerical control device, finding a torque command through speed loop control performed on the basis of said speed command and an amount of speed feedback from said position/speed detector, and performing current loop processing on the basis of the torque command and a feedback value of drive current detected by a current detector provided on said servo amplifier;
• and
• a positional difference correction controller to receive the move command from said numerical control device, while outputting a positional difference correction value required for correction of said positional deviation,
• wherein said positional difference correction controller includes a sign reversion monitor to monitor whether or not a sign of the move command inputted for the present process is different from a sign of the move command inputted on the previous process, a memory storing a predetermined positional difference correction value correspondingly to a machining shape, and a total correction amount memory storing the positional difference correction value added up in the process of machining each time said positional difference correction value is fetched from said memory;
• and
• said positional difference correction controller fetches the positional difference correction value corresponding to the machining shape from said memory and then outputs the fetched value so as to be added to said positional deviation, when said sign reversion monitor detects the reversion of the sign, and a value resulting from subtracting the added correction value stored in said total correction amount memory from the positional deviation for the present process is given as the positional deviation when machining is ended.

A move command correction method, comprising:

• (a) finding an amount of difference between a commanded position and an actual position occurring at the time of reversion of a direction of movement, prior to machining;
• (b) monitoring whether or not a sign of the move command is reversed while the machining is in progress on the basis of a machining program;
• (c) correcting a move command value by adding the amount of difference found in the above (a) to the move command when the reversion of the sign of the move command is detected;
• (d) performing a learning control on the basis of the move command corrected in the above (c) to correct further the move command;
• and
• (e) performing machining on the basis of the move command value corrected in the above (d).

A servo control system in which a move command is corrected, comprising:

• a numerical control device to issue a move command;
• a servo motor having a position/speed detector to drive a driven body;
• a servo amplifier having a current detector to control said servo motor;
• a position/speed/current control circuit to control said servo amplifier by finding a speed command from a positional deviation representing a difference between a position feedback outputted from the position/speed detector of said servo motor and a move command from said numerical control device, finding a torque command through speed loop control performed on the basis of said speed command and an amount of speed feedback from said position/speed detector, and performing current loop processing on the basis of the torque command and a feedback value of drive current detected by a current detector provided on said servo amplifier;
• a positional difference correction controller to receive the move command from said numerical control device, while outputting a positional difference correction value required for correction of said positional deviation;
• and
• a learning controller,
• wherein said positional difference correction controller includes:
• a sign reversion monitor to monitor whether or not a sign of the move command inputted for the present process is different from a sign of the move command inputted on the previous process;
• a memory storing a predetermined positional difference correction value correspondingly to a machining shape,
• wherein said positional difference correction controller fetches the positional difference correction value corresponding to the machining shape from said memory and then outputs the fetched value so as to be added to said positional deviation, when said sign reversion monitor detects the reversion of the sign, and also said learning controller performs learning control on the basis of the move command corrected by the positional difference correction controller to correct further the move command, thus carrying out machining on the basis of thus corrected move command.