Non-invasive laser based measurement of the helicoidal motion of a vibratory platform with three leaf-spring legs

A vibratory platform is a crucial part of automated assembly and has a similar structure to many parallel mechanisms. To investigate the platform, it is necessary to measure the helicoidal motion produced. This paper develops a new way of measuring the helicoidal motion by using reflective projection and by developing an analytical relationship between the measured vectors. A further relationship is developed between the cross sectional area of the laser light, the displacement of the platform and the output voltage from a photodiode. The study leads to a novel development of a non-invasive laser based measuring device. The paper further develops a dynamic calibration method, leading to calibration methods for both angular and linear displacements. The method is then confirmed by measurement to an accuracy of 20 μm.