| 摘要 |
PROBLEM TO BE SOLVED: To provide an automatic screw fastening device which can exactly measure measurement torque at forward rotation or reverse rotation.SOLUTION: The automatic screw fastening device comprises: a torque sensor which outputs an output voltage corresponding to load torque; and conversion means which converts the output voltage to torque which corresponds to the load torque and can output the converted measurement torque to the outside. The conversion means sets two or more gains which convert torque to the measurement torque with respect to fastening in a positive direction, and selects a gain which is used in the conversion of the measurement torque on the basis of a value of the inputted output voltage. As above, since optimum gain setting and gain selection adapted to an output characteristic of the torque sensor can be performed, torque measurement which is suppressed in errors more than before can be performed. Concretely, in the case that the output voltage outputted from the torque sensor is within a range of +C, a third gain G3 is selected, and the measurement torque is calculated by the third gain and the output voltage. |
