A new diagnostic technique for ball screw actuators

Ball screw actuators are electro-mechanical actuators that translate rotational motion to linear motion with little friction; they are used in precise engineering and particularly in aerospace applications where they replace hydraulic linear actuators. Until now, few diagnostic approaches have been developed with regard to fault detection and characterization of ball screw actuators. Here, a new diagnostic non-contact measurement technique is proposed to detect faults on ball screw actuators. A Hall effect sensor is applied to the ball return channel and the output signal is analyzed in-depth and validated through video monitoring and then post-processed with a new approach based on time domain analysis; maxima and minima distributions are used to distinguish between damaged and undamaged ball screw actuators. A considerable series of tests was performed in many configurations to define an optimal setup, and high repeatability was obtained. The proposed method can be easily applied to ball screw actuators because of the reduced dimensions of the components and thus, can be used to support the development of optimized repair and preventive maintenance policies that play a major role in the case of aerospace applications.