A 6-dof device to measure head movements in active vision experiments: geometric modeling and metric accuracy

This work describes a technique for measuring human head movements in 3D sp ace. Rotations and translations of the head are tracked using a light helme t fastened to a multi-joint mechanical structure. This apparatus has been d esigned to be used in a series of psycho-physiological experiments in the f ield of active vision, where position and orientation of the head need to b e measured in real time with high accuracy, high reliability and minimal in terference with subject movements. A geometric model is developed to recove r the position information and its parameters are identified through a cali bration procedure. The expected accuracy, derived on the basis of the pure geometric model and the sensor resolution, is compared with the real accura cy, obtained by performing repetitive measurements on a calibration fixture . The outcome of the comparison confirms the validity of the proposed solut ion which turns out to be effective in providing measurement of head positi on with an overall accuracy of 0.6 mm and sampling frequency above 1 kHz. ( C) 1999 Elsevier Science B.V. All rights reserved.