Pipe Compass - digital display measurement 

There are different ways one can calculate the distance and display the measured unit. In this log we will be looking at the different input sensors that are available to help measure the distance. 

• Linear magnetic encoder + rotary encoder: (combination of absolute encoder and incremental encoder) - The magnetic encoder is better than the capacitive encoder that is found in the digital caliper. The reason for magnetic being better is - the readings to not get effected by grease or dirty or moisture on the tape. Where as the capacitive encoder will not be able to read accurately with moisture, grease, dirt on the surface. This is the technique used inside most of the digital measuring tapes available in the market. 

• Rotary wheel + rotary encoder:  The distance moved using the rotary Wheel is recorded. This one can measure on curved surfaces as well as flat surfaces. 

Image source: Inscrutable tutorial by patrick panikulam. Project link.