Thread connection is widely used in mechanical connection. Torque wrench can feedback tightening torque in real time, and can apply more accurate tightening torque, which is widely used in engineering. Some assembly lines in aerospace or military field the tightening accuracy need to reach 0.1%, comparing with the only 1% accuracy of ordinary working wrench, the high precision torque wrench is needed to apply the high accuracy torque in aerospace or military field. Two methods are introduced to improve the measurement accuracy of the torque wrench. One is to design the transducer with pure torsional transformation when it is used. The other is to apply linearity correction to the transducer by circuit software. The results shows the accuracy of the torque wrench is 0.1%, which is much higher than ordinary work wrench.
For the traditional sensorless vector control systems of permanent magnet synchronous motor, a new sensorless vector control method is proposed based on the power factor control. On the basis of analysis of the mathematical models for the permanent magnet synchronous motor, established a power factor voltage reference frame system. The rotor position and speed is estimated by the control of power factor angle, and then from the point of view of efficiency drive to configure the stator current. This stator current is arranged in the vicinity of the current minimum trajectory. This method not only can control the speed, but also ensure high power factor and high drive efficiency of the permanent magnet synchronous motor. The simulation results proved the effectiveness and feasibility of this control method.
This paper reports results of further investigation of the direct torque control to a permanent magnet synchronous motor drive. A variable parameters speed controller is proposed from the point of view of speed control to accelerate the dynamic response and increase the control precision and decrease the torque ripple of the system. It is presented that a reference flux vector calculation direct torque control system with a speed controller using different proportional and integral coefficients, and a novel torque-limiting method is recommended. The simulation results show that the control system can improve its performances and limit torque ripple effectively.
For the contour accuracy of direct drive X-Y servo system is susceptible to changes of the load parameters and nonlinear disturbances including the friction , A quadratic optimal position controller with sliding contour tracking controller based on equivalent errors model is proposed to improve contour tracking performance and the robustness. The position controller is designed by the factorization of quadratic optimization on frequency domain. Based on Equivalent Errors model including the equivalent contour error and tangential error, the contour tracking problem is converted to the stabilization of error dynamic system. Simulation and experimental results show that the effects of nonlinear disturbances are reduced effectively and the designed controller has high contour tracking accuracy and strong robustness.
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