Bus Operator Workstation Evaluation and Design Guidelines Final Report (1997) / Chapter Skim
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Pages 313-394
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From page 313... ...
value in a time series. Also, the crest factor is the ratio of the peak value over the r.m.s.
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From page 314... ...
in the frequency domain approach, the methods used will be the power spectral density (PSD) and the transfer function or transmissibility.
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From page 315... ...
The goal of the dynamic testing of the transit bus seats is to relatively compare the ability of the seats to attenuate vibration. From this comparison, the seat that best isolates the vibration to the bus operator will be used in the bus operator workstation prototype.
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From page 316... ...
Procedure In the Phase ~ testing, various seat parameters and general features of the seats are measured. The seat parameters include suspension mass, suspension damping ratio, cushion stiffness, and cushion mass.
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From page 317... ...
Note that all seats are standard air suspension systems, except Seat #2, which is an active control air suspension (continuously varies air pressure to pneumatic spring) , and Seat #5, which is a height adjustable rigid support system.
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From page 318... ...
is placed on the rigid support underneath the seat pan cushion and as close as possible to the location where the operator would sit as recommended in ISO 2361. The other accelerometers are placed on the two masses suspended in the human ride simulator (#4 on lower mass, #5 on upper mass)
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From page 319... ...
is used for the rough road surface simulation, and the ~ mile fuel economy track is used for the smooth road simulation. A trial on the durability track consists of one lap counterclockwise around the track (Lane ~ and Lane 6, elements ~ through 14)
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From page 320... ...
, and SEAT%. For frequency domain analysis, transmissibilities for the accelerometer locations relative to the floor and power spectral densities of each accelerometer location are investigated.
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From page 321... ...
l 1,2; 1,3; 1,4; 1,5 | 1,2; 1,3; 1,4; 1,5 * For the durability track' the frequency analysis procedures can only be applied to one specific element of the track at a time.
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From page 322... ...
. Table D5.1: Seat Comparison T 1 T 2 ~ Seat 3 1 4 y y N N N Auto 1~.3 ~ 1 7 C Feature 5 1 6 N y Lap y 3 y 9.52 11.4 36.29 7 N Lap y Armrest | Headrest Adjustable r Seatbelt Seat Back Tilt Lumbar Air Chambers _ Seat Back Side Air Chamber Pan Side Air Chamber _ Height Adjust (cm)
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From page 323... ...
Since each element is designed to invoke a specific response, using the entire durability track trial is not appropriate. The chuck holes element was used because it most closely simulates rough road conditions and results in nearly vertical motion of the seat and ride simulator.
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From page 324... ...
Further, the rms results could be extrapolatec! to use with TSO 2631 to investigate how long a person shouIct be exposed to acceleration at that particular level.
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I b: SEAT % for Economy Track D-13
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From page 326... ...
Also, the transmissibilities of the lower mass and upper mass relative to the floor were found for both the durability and economy tracks. For the lower mass, the resonant frequency is known to be 4.25 Hz as stated above.
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From page 327... ...
Figure D5.2a-b below show the rankings for the lower and upper masses for the durability track, and Figure D5.3a-b below show the rankings for the economy track. As before with the SEAT rankings, the underlines indicate which values are not statistically different, as found from a two-sided l-test.
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From page 328... ...
2.0 1.5 0.5 0.0 ~_ , Figure DS.2a: Lower Mass Transm to o.e 0.6 0.4 0.2 0.0 ~1 ~/ 't 5 . Seat 1ssibilities for Durability Track 6 4 5 Seat Figure DS.2b: Upper Mass Transmissibilities for Durability Track D-16
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From page 329... ...
2.5 2.0 1 .5 0.5 1.0 0.0 Figure DS.3a: 2 1.5 1 0.5 o 3 2 4 1 7 6 5 Seat Lower Mass Transmissibilities for Economy Track ,~ 3 1 2 Seat Figure DS.3b: Upper Mass Transmissibilities for Economy Track D-17
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From page 330... ...
Finally, the pin jointed suspension group appears to perform the best of the seats, with the active scissor suspension being comparable in vibration attenuation. The reason why the passive scissor group did not do as well as the pin jointed is because the slider joints in the suspension linkage need a certain velocity to move to overcome friction (this phenomenon is called "stiction"~.
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From page 331... ...
Since Seat #4 has a cushion natural frequency that is closer to the critical frequencies of 4.25 Hz and 7.5 Hz, this indicates that the motion of the cushion may be greater for Seat #4. The transmissibilities of the two masses shown in Figure 5.6-5.7 show that indeed Seat #4 does produce a larger magnitude of vibration passed to the lower and upper masses compared to Seat #3.
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From page 332... ...
if the first place position has more than one seat listed, this indicates that from the data, the seats are not significantly different, usually due to high variance in the data. Looking at Table D6.l, the most important criteria for seat selection is the lower mass and upper mass transmissibility as stated in the testing plan.
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From page 333... ...
Indicates how much vibration passed to lower mass at ~4.25 Hz Indicates how much vibration passed to upper mass at ~ 7.5 Hz D-21
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From page 334... ...
Gilmore, B.~., 1995, "Bus Operator Work Station Evaluation and Design Guidelines Testing Plan," submitted to TCRP. Gouw, G.J., 1990, "Increased Comfort and Safety of Drivers of Off-Highway Vehicles Using Optimal Seat Suspension," SAE 901646.
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Sub-appendix D1: Figures D-23
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~ A Figure D-1.1: D-24 Bus Photo .~:.: :' - ' ~
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FIGURE INTENTIONALLY REMOVED. Figure D-1.2a: Seat D-25
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From page 338... ...
J ~ ~ - ~ W L4 _~ -. _ i' \ ~ Lo f /LS ~0 e1~ ~ ~2 Lo = 27.138 cm L5 = 6.985 cm L, = 3.3 15 cm 00 = 6.04 ° L2 = 33.655 cm 01 = 73.30 ° L3 = 33.497 cm 02 = 152.30 ° L4 = 37.817 cm 03 = 25.46 ° Figure D- I .2b: Seat I Suspension Linkage Dimensions D-26
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FIGURE INTENTIONALLY REMOVED. Figure D-1.3a: Seat 2 D-27
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From page 340... ...
//~/ /~2 l l /2 Lo L3 = 24.13 cm Lo=24.13 cm 1 Ll = 27.57 cm 0,= 151.07° L2 = 27.57 cm 02 = 28.93 0 ~1 \ , ~1 1 ~ f Figure D-1.3b: Seat 2 Suspension Linkage Dimensions D-28
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FIGURE INTENTIONALLY REMOVED. Figure D-1.4a: Seat 3 D-29
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From page 342... ...
! ~ : ~ ~ ~ : it: ~3 Lo -A- - ~ Lo = 27.138 cm L5 = 6.985 cm Ll = 3.315 cm 00= 6.04 ° L2 = 33.655 cm 01 = 73.30 ° L3 = 33.497 cm 02= 152.30 ° L4 = 37.817 cm 03 = 25.46 ° ~1 ~L~\~eo -~2 Figure D-~.4b: Seat 3 Suspension Linkage Dimensions D-30
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From page 343... ...
FIGURE INTENTIONALLY REMOVED. Figure D
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From page 344... ...
W:~ ~-L3 \~\ ~ ,~ >< I ~ I I ~ I .~: ~ Lo = 9.750 cm L3 = 9.750 cm Ll = 11.194 cm 01 = 29.43 ° L2 = 1 1.194 cm 02 = 150.57 ° Figure D-l.Sb: Seat 4 Suspension Linkage Dimensions D-32
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FIGURE INTENTIONALLY REMOVED. Figure D-1.6: Seat 5 D-33
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FIGURE INTENTIONALLY REMOVED. Figure D- 1.7a: Seat 6 D-34
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From page 347... ...
>A 1 Lo = 6.985 cm L3 = 27.918 cm L, = 27.918 cry 01 = 162.80 ° __ L2 = 6.985 cm 03 = 162.80° Figure D-~.7b: Seat 6 Suspension Linkage Dimensions D-35
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FIGURE INTENTIONALLY REMOVED. Figure D-1.8a: Seat 7 D-36
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From page 349... ...
f ~3 e1 a Lo e //// ~ Lo= 18.426 cm . 00 = 43.64 ° 1 ~ Lit = 30.174 cm Hi= 127.90 ° L2 = 1 1.5 1 8 cm 03= 175.670 L3 = 42.03 cm Figure D-~.8b: Seat 7 Suspension Linkage Dimensions D-37
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From page 351... ...
XXXXXXXXXXXXXXXXXXXXXXXXXXX: XXXXXXXXXXXXXXXXXXXXXXXXXXX: XXXXXXXXXXXXXXXXXXXXXXXXXXX: XXXXXXXXXXX X X X XXX XXXXXXXXX X: XXXXXXXXXXXXXXXXXXXXXXXXXXX: XXXXXXXXXXXXXXXXXXXXXXXXXXX: XXXXXXXXXXXXXXXXXXXXXXXXXXX: XXXXXXXXXXXXXXXXXXXXXXXXXXX' . XXXXXXXXXXXXXXXXXXXXXXXXXXX: XXXXXXXXXXXXXX - CXXXXXXXXXXX: XXXXXXXXXXXXXX: :XXXXXXXXXXX: XXXXXXXXXXXXXX: :XXXXXXXXXXX: XXXXXXXXXXXXXXXXXXXXXXXXXXX: ~XX~ _ Floor 2 Under Seat Cushion 5 3 Dummy Frame 4 Lower Dummy Mass Upper Dummy Mass Figure D-~.IO: Accelerometer Locations D-39
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Figure D-. I: Ride Quality Simulator in Seat D - 40
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-~' I it, -r -- -I In .
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- I HE m me Rae Cal ~ ' 1 ~ in _ L' ' :~ -be 1 ~ _ - -~1 -A r I -~1 ~ .
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From page 361... ...
{FIVE Phi (1~4) Figure D-1 .20: Floor RMS, RMQ, VDV for 1" Random Chuck Hoies O Gino 0~ MOO 0-400 0.2m ONYX} t 3 ~ Sect l .
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) _ 7 Figure D-1 .23: I ower Mass RMSt RMQ, VOV for ~ l Randon1 CtlUClt Holes D- 50
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From page 363... ...
R,~.o O'er V.D.~. (~-g^(ttO Figure D-.24: Upper Mass RMS, RMQ, VDV for 1,' Random Chuck Holes D- 51
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From page 364... ...
.. , ___ Figure D-1 .25: Floor films, RNIQ, VDV for Economy Track _ __ ' , _ _~ 1 1 ..
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From page 365... ...
) | - ~ R.MO ~ I -O-Y t~tJ~8 _ I_ Figure D-1 .28: Lower Mass RMS, RING, V0V for Economy Track D- 53
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From page 366... ...
(g-~(l~t . _ Figure D-1 ale: Upper Mass R~SI R~OI VDV far Economy -crack ~ -54
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From page 367... ...
Floor ~ ~0 N . ~_ 10 0 5 10 15 20 Under Seat Cushion ~ ~ 00 LoHrer Mass 10 l O ~ 10 15 20 Upper Mass 10~o= ~10213 15 20 Frmne r - I I 10 I Cal / o 10 15 pa Fret ueng, (Hz)
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From page 368... ...
Blow I trader Cushion (Mag) 10 1ea 1C 100 50 Q ~ i\ AS ~0k -fit It Floor ~ F=ne (Mag)
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From page 369... ...
Floors under Custion (Mag) ~ 10 as c' JO 100 = 50 as ~ -1W O ~ 4;0 .: -11;;i t Floor f Fit (Mag)
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From page 370... ...
Floor I Frame (flag} :~. 0 O Floor I Under Cushion (Mag)
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From page 371... ...
FIcor be ~ oo cat JO :: 10 10-2 Ir I ] 0 ~ 1 1 Lower Mass .~ 10° : 0 ~ 10 15 20 0 5 10 15 20 Ursder Seat Cushion Upper Mass 1oo 0 5 10 15 20 0 F- 18 l l 5 10 iS 20 Frequency (Hz)
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From page 372... ...
'01 10 ~ Floor I Under Cushion (Mag) 0 - o ~ r 'l0 / / 10 o ~10 15 20 Flow ~ Under Cushion (Ang)
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From page 373... ...
. 0 5 10 15 20 0 ~10 15 20 Under Seat Cushion 10 1 0 5 1Q8 I y 10 o Ups Mass 10° 10 15 20 DITTO 1 10-2 I .
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From page 374... ...
Floor f Under Cushion tMag)
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From page 375... ...
Floor :L 1 0 Cat -2 10 I 1 0° Under Seat Cushion 10 10 15 20 Frarre ~ 10 r I 0 5 10 15 20 Frequency Liz) Lower Mass 10° tO 15 2C ~5 13 15 20 Upper Mass 10° 10 2 0 ~ 10 1S 20 Frequency Adz)
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From page 376... ...
t Floor I Under Cushion (Mag) ce ~ 10° 1 Floor J FtarT e (I fag)
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From page 377... ...
- · 0 5 10 15 20 France loo ! tO-2, , J 10 15 20 Figure D-1.40: PSD's, Seat 46, Durability D - 65 t~ Mess 10° 10 15 20 Upper Mass 10 0 ~ -10 15 2G Fred (Hz)
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From page 378... ...
lo. ~ n 0 ~ 10° a, F oorl Under Cushion (Mag)
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From page 379... ...
FigureD-1.42: PSD's,Seat#7,Durability D - 67 Lower Mass O ~ 10 15 20 . Upper Mass 5 10 15 20 Frequer~cy (Hz)
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From page 380... ...
t Floor r Under Cushion (Mag) 10 ~- ~ ._ D i_ 0 ~ 10 ~0 Fhor ~ Under Cushion (Ang)
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From page 381... ...
, 0. 02 o T 0.02 0.01 o I 0.01 0.005 o Dummy Lower Class ~ ~~~ 0.02 0.01 n ' ~ Wt l ~ 0 5 10 15 0 5 10 15 Suspension Dummy Upper Mass I .
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From page 382... ...
10' Dummy Lower hlassIFloor 10°| 10° 10-' 15 0 10' 10° . .~d : ~ 10 15 Dummy Upper MassIFloor ~\;,A~~, 1o-l 0 ~ 10 16 Frequency (H~)
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From page 383... ...
Dummy Lower brass . ~ -O ~ 10 15 Dummy Upper Mass ,.
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From page 384... ...
I . ~_\ 'O ~ Frequency (Hey 1o1 10° Dummy Upper MassIFloor 1~ ~~\ 1 10-' ~.
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From page 385... ...
02 w o 0.04 0.01 I 0.005 O Dummy Lower Mass 'O ~ 10 Suspension .
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From page 386... ...
. O ~ Dummy FramefFloor 10 100 10-' 10 15 0 Dummy Lower h1assIFloor it, ~ 10 15 Dummy Upper MassIFloor 1 ~ 10'1 1~ 10°~ 1.0 ~ 0 ~ 10 15 0 ~10 Frequency (Hz)
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From page 387... ...
. O __ 0 ~ 10 15 Suspension 0.04 0.02 0.1 0.05 Dummy Lower Mass ,~, 10 15 Dummy Upper Class few 0 ~ 10 15 0 Dummy Frame -1 ' ' 1 ~ 10 15 Frequency (H.)
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From page 388... ...
1 o 1 10° 10 sol 10° 1 o -1 SuspensionIFloor 10' 10° -1 Dummy Lower h~lassIFloor ~w ~v~x 0 ~ 10 15 0 ~10 15 Durnnny FramefFloor O ~ Frequelloy (Hz) 1ol 10° 10 15 0 [: ummy Upper MassIFloor ; An: -11 ~ 10 15 Frequency (Hz)
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From page 389... ...
., Dummy Lower Mass 0.04 10 15 0 Suspension 002 J: A o ~ 10 15 Dummy Upper Mass 0.1, 0.05 o 10 15 0 ~ O ~,~ 0 ~ 10 15 Frequerley (Hz) At 10 Frequency (Hz)
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From page 390... ...
Figure D-1.53 10' .: I, 10 15 Dummy Upper MassfFloor 10° 1Q ' ' o ~ 10 15 Frequency (Hz) Seat 5 Average Transm~ssibilities, Economy D - 78
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From page 391... ...
~ O ~ Dummy Lower Mass 0.04 15 -O 0.05 10 15 Frequency (H~)
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From page 392... ...
0 ~ 10 Frequency (Hz) 10' 10° 10-1 Dummy Lower 191assIFloor ' '' '1 ~~N 10 15 0 ~ 10 15 Dummy Upper MassIFloor 10° 10 ' 16 0 ~ 10 Frequency (Hz)
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From page 393... ...
10 15 Frequency (Hz) 10 15 Figure D-:.56: Seat 7 Average PSD Functions, Economy D- 81
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From page 394... ...
Dummy Lower hlassIFloor ~ 10 15 Dummy Upper MassIFloor it.
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