A Biarc Fitting Algorithm for Concentric Cable-Driven Manipulators Working in Oropharyngeal Swab Samplings

A biarc fitting algorithm is proposed for the designed concentric cable-driven manipulator working in oropharyngeal (OP) swab samplings. This algorithm makes the concentric cable-driven manipulator composed of discrete nodes have a high degree of fit with the continuous curve planned by the biarc method. Three advantages of this algorithm are as follows. First of all, by adjusting the tangent at the end point, the problem of large deviation fitting between the actual path and the planned path caused by the fixed tangent at the end point during path tracking is solved. In addition, by adjusting the given starting point, the problem of large deviation fitting between the concentric cable-driven manipulator and biarc curve caused by non-integer number of nodes during configuration fitting is solved. Further, by adjusting the proportionality coefficient, the problem of large deviation fitting between the concentric cable-driven manipulator and biarc curve caused by the odd-even variation of the number of moving nodes during configuration fitting is solved. Tracking the planned paths of OP-swab sampling, the simulation and experiment verify the effectiveness of the biarc fitting algorithm for concentric cable-driven manipulators working in OP-swab samplings.