Research on control system of electric tightening wrench based on rotational speed difference method

With the extensive use of high-strength bolts, the method of controlling the output torque of tightening wrench becomes particularly important. According to the mechanical characteristics of series excited motors, this paper proposes a spanner control system model based on speed difference method. In this result, we built the experimental platform, measured the motor speed difference and the reducer output torque in the same step, and reduced the interference of noise on signal acquisition by weighted recursive average filtering algorithm. The least square method was used to curve fit the data of output torque and speed difference, and the correlation coefficient was used to seek the optimal relation expression of the two. As a result, the test shows that the system error is within ± 4%, which verifies the feasibility of this control system scheme.