The Virtual-Spine Platform-Acquiring, visualizing, and analyzing individual sitting behavior

Abstract

Back pain is a serious medical problem especially for those people sitting over long periods during their daily work. Here we present a system to help users monitoring and examining their sitting behavior. The Virtual-Spine Platform (VSP) is an integrated system consisting of a real-time body position monitoring module and a data visualization module to provide individualized, immediate, and accurate sitting behavior support. It provides a comprehensive spine movement analysis as well as accumulated data visualization to demonstrate behavior patterns within a certain period. The two modules are discussed in detail focusing on the design of the VSP system with adequate capacity for continuous monitoring and a web-based interactive data analysis method to visualize and compare the sitting behavior of different persons. The data was collected in an experiment with a small group of subjects. Using this method, the behavior of five subjects was evaluated over a working day, enabling inferences and suggestions for sitting improvements. The results from the accumulated data module were used to elucidate the basic function of body position recognition of the VSP. Finally, an expert user study was conducted to evaluate VSP and support future developments.

Fig 1. Virtual-Spine system overview.

Left: VSP-RTM: Real-Time Monitoring system; Center: VSP-RTV: Real-Time Visualization system; Right: VSP-ADV: Accumulated Data Visualization system.

Fig 2. Virtual-Spine: Real-time monitoring and visualization system.

The Real-time Monitoring System: a) in combination with a conventional office chair showing the VSP back and seat mats attached with sensors; b) the connecting hardware of the VSP mat to the computer system; The Real-time Visualization System: c) a laptop running the posture recognition system (see also Fig 4).

Fig 3. Sitting postures.

a) Upright; b) Slump; c) Normal; d) ArmBackLeaning; e) RightOverLeft (or the opposite: LeftOverRight); f) TwistLeft (or the opposite: TwistRight); g) PokingChin; h) ArmLeaning.

Fig 4. Real-time visualization module in VSP.

a) Posture recording in an office environment, here, the posture Normal is shown (see also Fig 1 left and Fig 3c); b) Left: the posture-recording GUI and information of the current pose, Right: the pressure pattern of the Normal pose.

Fig 5. VSP-ADV with posture type-dependent coloring.

The interactive pose bar charts are ordered based on their time sequence and only those poses are shown with a duration d of 60 sec. < d < 1,000,000 sec. The figure shows also the details on demand feature, providing information about the selected posture period. The X axis represents the posture time points following the filtering rule, whereas the Y axis represents the posture duration.

Fig 6. VSP-ADV with scoring posture-dependent coloring.

Score colors, in this mode represented by the bars: Green: good with d ≤ 8 min., Orange: warn with 8 min. < d ≤ 20 min., Red: bad with 20 min. < d. Subject 1 showed a quite good sitting behavior, as no red warning is shown at all. Please see also the caption of Fig 5.

Fig 7. VSP-ADV on a smart phone and a high-resolution tiled display.

During the development of VSP-ADV we were focusing on an application compatible with high-resolution displays (right) as well as smart phones (left).

Fig 8. VSP-ADV sitting posture charts: Time lines.

A high-resolution image of all postures with a duration d > 10 sec. ordered by starting time. Working day-specific sitting posture patterns can be evaluated. See Fig 10 for posture X labels.

Fig 9. VSP-ADV sitting posture charts: Posture patterns.

A high-resolution image of all postures with a duration d > 10 sec. ordered by pose duration. Subject-specific sitting posture patterns can be evaluated.

Fig 10. VSP-ADV sitting health posture charts: Time lines.

A high-resolution image of all postures with a duration d > 10 sec. ordered by starting time. The duration-related rating is shown here. See Fig 8 for time X labels.

Fig 11. VSP personal sitting behavior.

Personal Rating, Global Rating, First Changes, Sitting Behavior rating before and after the study.

Fig 12. VSP-ADV potential target groups.

Potential target groups.

Fig 13. VSP-ADV feature ratings.

Ratings of the different features part of VSP-ADV.

Fig 14. VSP-ADV visualization quality.

Visual Quality of VSP-ADV: Esthetic Coloring, Coloring Differentiation, Posture Symbols, and Readability.