Is motion capture-based biomechanical simulation valid for HCI studies?

Abstract

Motion-capture-based biomechanical simulation is a noninvasive analysis method that yields a rich description of posture, joint, and muscle activity in human movement. The method is presently gaining ground in sports, medicine, and industrial ergonomics, but it also bears great potential for studies in HCI where the physical ergonomics of a design is important. To make the method more broadly accessible, we study its predictive validity for movements and users typical to studies in HCI. We discuss the sources of error in biomechanical simulation and present results from two validation studies conducted with a state-of-the-art system. Study I tested aimed movements ranging from multitouch gestures to dancing, finding out that the critical limiting factor is the size of movement. Study II compared muscle activation predictions to surface-EMG recordings in a 3D pointing task. The data shows medium-to-high validity that is, however, constrained by some characteristics of the movement and the user. We draw concrete recommendations to practitioners and discuss challenges to developing the method further.

Performance and Ergonomics of Touch Surfaces

“…In smartphone conditions amplitudes were shorter than marker error limits, limiting the applicability of the full-body simulation. Because biomechanical simulation has limited validity for small-scale movements [1], only 10 users participated in the two smartphone conditions in addition to the other ones. The remaining 30 participated in all other conditions except the smartphone conditions.…”

“…[1]). We clean marker data from occlusions, reflections, and other artifacts with a heuristic approach and Kalman smoothing.…”

“…Although biomechanical computations have been known for decades [30], tools for motion capture based biomechanical simulation [6] and high-fidelity muskuloskeletal models 1 have reached maturity only recently. In HCI, the tools appeared in publications last year [1].…”

“…In HCI, the tools appeared in publications last year [1]. The simulation provides a great opportunity to "look inside the body" of users as they interact with computers, with no obtrusive instruments.…”

“…The use of biomechanical simulation not only provides a very rich description of biomechanical events in the body, it also overcomes challenges that the traditional ergonomics instruments have, such as goniometers and surface-EMG. Recently, the predictions of mocap-based biomechanical simulation were validated against EMG data [1]. The results were positive for all participants, highlighting that the correlation is higher for aimed motions involving larger muscles on male subjects closer to the population average in anatomical dimensions.…”