Perception Coherence Zones in Vehicle Simulation

Abstract

A perception coherence zone (PCZ) designates the range of inertial motion levels that, although not being a one-to-one match with the visual motion levels, are still considered by the subjects as being part of a coherent movement. Two types of PCZs were studied: amplitude PCZs and phase PCZs. Amplitude and phase coherences zones were measured for different types of stimulus frequency and amplitudes, for different degrees-of-freedom and using different motion simulators. The resulting data were compiled and it was demonstrated how perception coherence zones can be used to assess motion cueing solutions, and to derive motion cueing criteria. The coherence zones criteria were shown in a modified Sinacori plot. In a Sinacori plot, motion criteria are represented in terms of acceptable motion gain and phase distortion at the frequency of 1 rad/s. Since coherence zones were measured at different frequencies and amplitudes, it was possible to expand that representation to different frequencies and amplitudes. The coherence zone assessment method and criteria provide three important additions to the already available criteria. First, it presents not only criteria for desirable motion stimuli, but also offers a systematic, objective, human-perception-based method to measure the limits of the criteria. Second, the coherence zones method and criteria add a third and fourth dimension to the Sinacori plot: frequency and amplitude. By doing so, the coherence zone criteria do not depend on a specific motion filter structure. Third, by offering a measurement method and allowing different frequencies and amplitudes to be chosen, the coherence zones method can provide simulator-based, task-specific criteria. However, coherence zones as a metric, that is, as a measure of the perceived coherence of the inertial feedback provided, is platform and task independent.