1. Myroslav Bachynskyi Gregorio Palmas Antti Oulasvirta Jrgen Steimle Tino Weinkauf http://resources.mpi-inf.mpg.de/touchbiomechanics Performance and Ergonomics of Touch Surfaces: A Comparative Study using Biomechanical Simulation 2. A variety of surfaces are treated the same 2 3. Ergonomics issues with touchscreen interaction 3 Gorilla arm1 Trapezius fatigue2 Bad neck posture3 1http://www.wired.com/gadgetlab/ 2010/10/gorilla-arm-multitouch 2Bachynskyi, ToCHI 2015 3Young, Work 2012 4. Previous work has not compared surfaces for performance and ergonomics 4 Device Physical ergonomics Performance Body posture, thumb joints and hand muscle usage [Kim2012] Accuracy model of thumb [Park2010] Wrist posture, hand muscle usage [Young2013] Accuracy [Parhi2006] Posture [Barbe2012] Discomfort [Davis2014] Touch area model [Wang2009] Performance [Sears1991, Oehl2007] User preference [Mller-Tomfelde2008] Accuracy models [Holz2010,2011] Performance [Micire2007, Sasagonar2009] Accuracy [Beringer1985] Performance [Po2004] 5. Contributions 1. The first study using motion capture based biomechanical simulation 2. Expose differences among surfaces and postures 1. Ergonomics (muscles, joints) 2. Postures 3. Performance (Fitts throughput) 3. Dataset for further analyses of surfaces 5 6. Method 6 7. Method overview 40 participants 7 Pointing task MoCap recording Biomechanical simulation Throughput modeling Ergonomics Performance The dataset 8. Pointing task covering the surface Public Display Smartphone 2 handsTablet TabletopLaptop Smartphone 1 hand 9. Motion capture and force data are inputs for performance and ergonomics computation 9 10. Speed, accuracy and performance extracted from end-effector marker trajectory 10 Individual aimed movements Endpoints at target A Endpoints at target B X Y Z Time Coordinatevalue 11. Biomechanical simulation extracts multiple physical ergonomics indices 11 12. Results 12 13. The dataset: 6 surfaces, 40 users, 107,000 aimed movements x 1,182 variables Variable blocks Experiment metadata 3D movement trajectory Input performance Physical ergonomics Format Frame level data Aggregated per trial 13 Posture MovExp [Palmas 2014] Demo: Booth H3 in Exhibit Hall morning break tomorrow 14. Differences are up to 40% in Throughput and 80% in Total muscle recruitment 14 15. We analyzed which muscles explain these differences 15 Tablet Laptop Tabletop Public Display Smartphone (2 hands) Smartphone (1 hand) 16. 95% of participants strained their neck and upper back BUT only with portable devices 16 17. Strain by bad posture 17 Public Display Smartphone 2 hands Tablet TabletopLaptop Smartphone 1 hand 18. Posture clustering reveals further differences within each surface Mean interaction posture Posture clusters 18 19. Neck joint loads exceed those of correct posture in up to 5 times 2,000 1,000 0 Neck joints 20. Loads in lumbar spine are up to 2.5 times larger during interaction in incorrect posture 10,000 5,000 0 Lumbar spine joints 21. Summary Graduating in 2015 http://resources.mpi-inf.mpg.de/touchbiomechanics/ Performance Ergonomics Postures