Patent ID: 8659254

Claim:
A servo system comprising: a servo motor; a controller configured to output an instruction signal that controls driving of the servo motor; an encoder configured to detect an operation of the servo motor and output a feedback signal representing the detected operation; a servo driver configured to generate an instruction value for the operation of the servo motor using the instruction signal from the controller and the feedback signal from the encoder, and drive the servo motor in accordance with the instruction value; and a safety monitor configured to output a stop signal to be sent to the servo driver in order to stop an output of torque from the servo motor when the operation of the servo motor is in an abnormal condition, wherein the servo driver stops the output of torque from the servo motor as a result of receiving the stop signal from the safety monitor, and the safety monitor acquires from the servo driver the instruction value and a feedback value that is obtained based on the feedback signal as a result of the servo motor having been driven in accordance with the instruction value, and generates the stop signal when a determination value calculated with the instruction value and the feedback value is in a first abnormal condition or when the determination value is not in the first abnormal condition and at least one of the instruction value and the feedback value is in a second abnormal condition.