The Virtual Haptic Back (VHB): A Virtual Reality Simulation of the Human Back for Palpatory Diagnostic Training

The Virtual Haptic Back (VHB) is designed as an aid to teaching medical palpatory diagnosis. It uses two PHANToM 3.0 haptic interfaces (SensAble Technologies, Inc.), permitting palpation by force feedback with two fingers of a life-sized virtual human back. A graphics image of the back is displayed on a monitor a few inches behind the palpable back. Movement of back components, e.g., skin or underlying vertebrae, by exertion of palpatory force by the user is reflected graphically. Mechanical properties of the back, e.g., spring constants of the surface, are chosen based on feedback from physicians experienced in palpatory diagnosis. Although subjective evaluation of the VHB by 81 users over 2 years is positive, results have not yet shown students being trained in palpatory diagnosis to perform better than controls subjects. Results guide modifications of the haptic model itself and of the user tasks employed during testing.