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[ HFES 2010 ]

[ HFES 2010 ]. Effects of Ramp Slope and Height on Usability and Physiology during Wheelchair Driving. 2010. 09. 28. POSTECH HSD Lab, Republic of KOREA Chung Sik Kim, Donghun Lee, Jeehea Lee, Sunghyuk Kwon, and Min K. Chung. Introduction (1/4). 1. POSTECH

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[ HFES 2010 ]

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  1. [ HFES 2010] Effects of Ramp Slope and Height on Usability and Physiology during Wheelchair Driving 2010. 09. 28. POSTECH HSD Lab, Republic of KOREA Chung Sik Kim,Donghun Lee, Jeehea Lee, Sunghyuk Kwon, and Min K. Chung

  2. Introduction (1/4) 1 POSTECH Human System Design Laboratory

  3. Introduction (2/4) 2 POSTECH Human System Design Laboratory

  4. Introduction (3/4) 3 Width Literature review surface length Height Slope (Height : Length) Length Ramp slope Prior studies 1:6 ~ 1:6.7 Elmer (1957), Canale et al. (1991) 1:10 Walter (1971) 1:12 ADAAG (1997), Sanford et al. (1997) 1:16 ~ 1:20 Steinfeld et al. (1979) ※ ADAAG = Americans with Disabilities Act Accessibility Guidelines POSTECH Human System Design Laboratory

  5. Introduction (3/4) 3 Width Literature review surface length Height Slope (Height : Length) Length Ramp slope Prior studies Participants 1:6 ~ 1:6.7 Elmer (1957), Canale et al. (1991) Young & Healthy 1:10 Walter (1971) - 1:12 ADAAG (1997), Sanford et al. (1997) Diverse physical capacity 1:16 ~ 1:20 Steinfeld et al. (1979) Older individuals ※ ADAAG = Americans with Disabilities Act Accessibility Guidelines POSTECH Human System Design Laboratory

  6. Introduction (3/4) 3 Width Literature review surface length Height Slope (Height : Length) Length Ramp slope Prior studies Participants Surface length 1:6 ~ 1:6.7 Elmer (1957), Canale et al. (1991) Young & Healthy - 1:10 Walter (1971) - 300 cm (10 ft) 1:12 ADAAG (1997), Sanford et al. (1997) Diverse physical capacity 900 cm (30 ft) 1:16 ~ 1:20 Steinfeld et al. (1979) Older individuals 1200 cm (40 ft) ※ ADAAG = Americans with Disabilities Act Accessibility Guidelines POSTECH Human System Design Laboratory

  7. Introduction (4/4) 4 Width Literature review surface length • Examine the effects of the ramp slope and height on usability and physiology of wheelchair users • Suggest the appropriate ramp slope for a specified ramp height Height Slope (Height : Length) Length Objective POSTECH Human System Design Laboratory

  8. Methods (1/4) 5 Participants • 30 people (11 males and 19 females) participated in the experiment • Age is ranging from 23 to 32 (Average = 25.4, Standard Deviation = 2.10) • No one had experience of operating wheelchair • Participant screening • To consider various forces in the test sample • Push force of the dominant hand was measured in seated posture POSTECH Human System Design Laboratory

  9. Methods (2/4) 6 Variables • Independent variables • Ramp slope(5 levels) – 1:6, 1:8, 1:10, 1:12, 1:14 • Ramp height(3 levels) – 15 cm, 30 cm, 45 cm • Dependent variables Prior studies Height of a stair step Height of building entrance POSTECH Human System Design Laboratory

  10. Methods (2/4) 6 Variables • Independent variables • Ramp slope(5 levels) – 1:6, 1:8, 1:10, 1:12, 1:14 • Ramp height(3 levels) – 15 cm, 30 cm, 45 cm • Dependent variables Total time • Velocity = surface length / Total time POSTECH Human System Design Laboratory

  11. Methods (2/4) 6 Variables • Independent variables • Ramp slope(5 levels) – 1:6, 1:8, 1:10, 1:12, 1:14 • Ramp height(3 levels) – 15 cm, 30 cm, 45 cm • Dependent variables POSTECH Human System Design Laboratory

  12. Methods (2/4) 6 Variables • Independent variables • Ramp slope(5 levels) – 1:6, 1:8, 1:10, 1:12, 1:14 • Ramp height(3 levels) – 15 cm, 30 cm, 45 cm • Dependent variables Anterior deltoid Extensor carpi radialis Triceps brachii Posterior deltoid • Pulse rate difference = pulse rate after task – pulse rate before task POSTECH Human System Design Laboratory

  13. Methods (3/4) 7 Apparatus • Ramp • Wheelchair • Noraxon Telemyo 900 •  EMG activity • Polar RS 400 pulsemeter •  Pulse rate • Sony DCR HC 40 camcorder •  Video recording ※ Width 700 mm × Depth 1040 mm × Height 875 mm POSTECH Human System Design Laboratory

  14. Methods (4/4) 8 Procedure • Rest until pulse reached in stable state • Ascending ramp as natural as possible • EMG activity, total time, pulse rate, perceived discomfort were measured Descending Ascending Rest • Descending ramp as natural as possible • Only perceived discomfortwere measured × 15 experimental conditions POSTECH Human System Design Laboratory

  15. Results and Discussion (1/6) 9 Total time Velocity Perceived discomfort while ascending EMG activity of triceps brachii

  16. Results and Discussion (2/6) 10 Usability Total time Velocity Perceived discomfort Physiological characteristic EMG activity Pulse rate difference Usability Physiological characteristic Low High Height Low High Height POSTECH Human System Design Laboratory

  17. Results and Discussion (2/6) 10 Usability Total time Velocity Perceived discomfort Physiological characteristic EMG activity Pulse rate difference Usability Physiological characteristic Steep Gentle Slope Steep Gentle Slope POSTECH Human System Design Laboratory

  18. Results and Discussion (3/6) 11 • 1:6 slope showed low usability and the worst physiological characteristics •  1:6 is not suitable for ramp design • It is not concurred with Elmer (1957) and Canale et al. (1991) •  Due to the difference of test sample Elmer and Canale et al. This study vs Young and Healthy Wide spectrum of physical capacity POSTECH Human System Design Laboratory

  19. Results and Discussion (4/6) 12 • There is no significant difference between 1:10 and 1:12 •  1:10 can be used for ramp design instead of 1:12 suggested by ADAAG POSTECH Human System Design Laboratory

  20. Results and Discussion (5/6) 13 • Slope effect at 15 cm showed similar trend with those at 45 cm • But, differences among five slopes increased as the height increased • Slope effect was minor at 15 cm • Slope effect was major at 45 cm POSTECH Human System Design Laboratory

  21. Results and Discussion (6/6) 14 • Relationship between slope and surface length when height was fixed • Steep slope = High reaction force + Short surface length • Gentle slope = Low reaction force + Long surface length •  Slope effect was minor at 15 cm (low height) • Slope effect was major at 45 cm • Overall task difficulty increased with height increasing • Participants could not keep comfortable pace at 45 cm with steep slope Trade-off

  22. Conclusions (1/2) 15 Summaries • There was no significant difference between 1:10 and 1:12 •  1:10 can replace 1:12 (suggested by ADAAG) • At 15 cm, slope effect was minor • [A] Perceived discomfort of 1:8 at 15 cm < [B] Perceived discomfort of 1:12 at 45 cm • 1:8 may be acceptable if the installation space for a gentler ramp is not sufficient • 1:6 led to the worst on usability and physiological characteristics •  should not used for ramp design B A POSTECH Human System Design Laboratory

  23. Conclusions (2/2) 16 Further studies • Increasing number of the aged… • Only young people were participated in the experiment • Although we considered the push forces the other characteristics can affects the suitable ramp slope • (ex: psychophysical characteristics, range of motion……) POSTECH Human System Design Laboratory

  24. Q & A Thank you!! POSTECH Human System Design Laboratory

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