A control system of a power unit in accordance with the present invention corrects a basic command value of an electric motor 2, which has been determined such that the detection value of a driving force to be applied to a rotary member 5 is converged to a desired value, according to a manipulated variable determined by an observer 16. The electric motor 2 is controlled according to a desired control value after the correction. The observer 16 determines the manipulated variable such that the driving force based on the desired control value is brought close to the resultant force of a force indicated by the rotary member 5 and an inertial force.

A monitoring device of a robot system including: a current sensor detecting a value of a current flowing through the servo motor; a current/torque converting the value of the current flowing through the servo motor which is detected by the current sensor into a torque value; a driving torque estimating section estimating at least a part of driving torque required to drive the servo motor; a differential torque calculating differential torque between the torque value obtained by conversion in the current/torque converting section and an estimated value of the driving torque; an external force converting the differential torque calculated by the differential torque calculating section into an external force applied to the robot; and a stop signal generating section which generates to stop the robot based on a value of the external force obtained by conversion in the external force converting section, and supplies the stop signal to the controller.

According to one embodiment, a robot control device is used for a robot arm including a link and a motor for rotationally driving the link. The robot control device includes a derivation part. The derivation part derives a first estimated value including a variation of a rotation angle of the link and a second estimated value including a variation of a rotation angle of the motor, based on an angular velocity and a current reference value of the motor. Furthermore, the derivation part derives an external force generated to the robot arm, based on a difference between the first estimated value and the second estimated value.

A monitoring device of a robot system including: a current sensor detecting a value of a current flowing through the servo motor; a current/torque converting the value of the current flowing through the servo motor which is detected by the current sensor into a torque value; a driving torque estimating section estimating at least a part of driving torque required to drive the servo motor; a differential torque calculating differential torque between the torque value obtained by conversion in the current/torque converting section and an estimated value of the driving torque; an external force converting the differential torque calculated by the differential torque calculating section into an external force applied to the robot; and a stop signal generating section which generates to stop the robot based on a value of the external force obtained by conversion in the external force converting section, and supplies the stop signal to the controller.

According to one embodiment, a robot control device is used for a robot arm including a link and a motor for rotationally driving the link. The robot control device includes a derivation part. The derivation part derives a first estimated value including a variation of a rotation angle of the link and a second estimated value including a variation of a rotation angle of the motor, based on an angular velocity and a current reference value of the motor. Furthermore, the derivation part derives an external force generated to the robot arm, based on a difference between the first estimated value and the second estimated value.