Condition monitoring of slider crank mechanism of a linear servo mechanism using encoder sensor signal harmonics

Although clearance in mechanisms facilitates manufacturing and assembly, it will lead to undesirable results such as an increase in vibration and a decrease in accuracy. Joint clearance is considered as the main cause of errors in the position and the direction of the links. This research has investigated the possibility of using encoder signals to estimate the extent of clearance in the joints of a slide crank servomechanism. The output signal of the encoder was studied in three modes of zero, low and high clearances. It was done on the point of the part that serves as a link for servomechanism. The output signals of encoder were tested, analyzed and compared with those in joints with/without clearances. It was found that the signals had a sinusoidal waveform in the joint with ideal clearance but it has a distorted waveform in the joint which has high clearance. The results show that the distortion available in encoder signals may be used as a criterion to estimate and monitor clearance condition in slide crank mechanisms