Assay of Direct Digital Output Floating-Wiper Inductive Displacement Sensor

A direct digital output non-contact inductive type displacement sensor whose principle of operation alone was presented earlier, is analyzed to ascertain parameters that influence the errors in the output. Further, its efficacy is established through results obtained from a prototype unit built and tested. The proposed direct digital output non-contact inductive displacement transducer employs the popular successive approximation register (SAR) method of conversion. The digital output is proportional to the displacement of the contactless (floating) wiper and is unaffected by the variations in the coupling capacitor that is formed between the wiper and the inductive element. Test results on a prototype transducer indicated a worst-case error of 0.9 %.