Fig. 2
From: Non-orthogonal one-step calibration method for robotized transcranial magnetic stimulation
A The mechanical relationships among the coil, marker, and probe. B Set-up of the calibration experiment with an optical tracking device. C The mechanical drafting of the probe; the distance is marked in mm. D Principles of coil/end effector and robot/world calibration: a model of a figure-eight-coil is attached to the robot’s end effector E, a marker is fixed on the top of the stimulation coil, and a probe is fixed at the bottom of the coil