The Virtual Haptic Back: Detection of Compliance Differences

The ability of human subjects to distinguish small compliance differences in adjacent regions was tested with the Virtual Haptic Back (VHB), a simulation of human backs designed to aid in teaching medical palpatory diagnosis. The VHB uses two PHANToM 3.0 haptic interfaces (SensAble Technologies, Inc.). The contours and compliance properties of the backs are represented graphically and haptically. Medical students practiced 8 times over 2 weeks on the VHB, finding regions of altered compliance, the locations of which varied randomly. Baseline compliance was 2.52 mm/N; compliance in the abnormal regions ranged from 2.45 to 0.97 mm/N. Following the practice session the threshold of detection is 2.25 mm/N, an 11% difference from baseline.