Improving cable length measurements for large CDPR using the Vernier principle

International audienceCable lengths is an important input for determining the state of a CDPR. Using drum with helical guide may be appropriate for small or medium-sized CDPR but are problematic for large one. Another issue is the initialization of the cable length as measurements based on drum rotation are incremental. We propose to address automatic initialization and improvement of cable length measurements by using regularly spaced color marks on the cable combined with color sensors in the mast of the CDPR. We show that this disposition allows one to automate the initialization issue and then how it allows to get regularly accurate estimation of the cable length by using the Vernier principle