The Influence of the Contact Geometry of Active Seating Systems on the Human Perception Threshold

Abstract

AbstractAn active seating system is designed to promote dynamic sitting. To achieve this, the user’s posture is permanently monitored by sensors. If the user does not change posture independently within a defined period of time, actuators exert a strain on the buttocks to create subconscious discomfort. This discomfort is intended to induce the user to change posture without consciously noticing it. In previous studies, measurements were carried out on an automated test bench based on a modified office chair. In this context, the actuating forces and displacement at which the user consciously perceives discomfort were determined, as well as the influence of different actuator speeds. The first measurements were carried out with a flat surfaced actuator of 20 mm diameter. This paper investigates the influence of the contact geometry (shape and size) of active seating systems on the human perception threshold. For this reason, the experiments are repeated with nine geometrically different contact geometries with flat, round, and pointed surfaces of 20, 40, and 60 mm diameter. In order to be able to compare results, all measurements are performed with the same group of participants. In addition, questionnaires are used to record subjective parameters during the test. Based on the results, the paper inquires whether, in addition to the expected influence of the diameter of the actuator, a significant influence of shape and speed can be observed.KeywordsHuman factorsSitting ergonomicsDynamic sitting