Bus Operator Workstation Evaluation and Design Guidelines Final Report (1997) / Chapter Skim
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Pages 397-440
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From page 397... ...
. - Be sure to accommodate the 5th-percentile female to the 95th | percentile male as shc wn in SAE J833 (accommodation)
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From page 398... ...
acceleration incidents are not due to mechanical failure, but caused by foot placement errors/or insufficient height difference between the brake and accelerator pedals (Proctor and Van Zandt, ~ 994~.
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From page 399... ...
An optimum location of the pedal fulcrum: Ayoub and Trombley (1967) - Usecl a generic treadle pedal - Measure : travel distances of the ball-of-foot Pedal Actuation ~ Results | Optimum Location of Mechanism Pedal Fulcrum constant angle The closer the fulcrum is to the heel, forward of the ankle actuation (12 deg.)
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From page 400... ...
4. An optimum angle of foot pedals: Hertzberg and Burke ~ ~ 97 - Used an aircraft brake pedal - Measure: maximum pedal forces An optimum angle of between 25 and 35 degrees produced the highest forces.
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From page 401... ...
Since many brake pedal controls require some amount of force, the geometric relationship between the operator's leg and foot and the position and angle of the pedal is an important consideration. - Depending on the height of the seat, foot pedals not only must be placed within reach, but they also must operate in a direction that is compatible with the force application vector.
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From page 402... ...
of Design Variables No. of Ergonomic Design Variables pedal plate ~ ~ ~ ~ O pedal arm 5 O pedal mounting base LO 3 => The pedal plate is the main pedal component interfaced with a driver foot.
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From page 403... ...
WO - Workstation Origin (the point on the workstation platfor~n underneath a seat reference point of SAE 50%; 5. PMBRP - Pedal Mounting Base Reference Point.
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From page 404... ...
The shaded boxes represent ergonomic pedal design variables.
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From page 405... ...
pedal plate length PDI pedalplatewiclth ~ PD2 pedal plate shape PD4 pedal plate horizontal PD5 angle from the floor pedal plate lateral angle PD6 from a vehicle center line P3 angle ranges PD7 horizontal distance of PA PPRP from WO vertical distance of PPRP Pug lateral distance of PPRP PD ~ O from WO pedal plate material PD! pedal actuation angle PD20 pedal actuation force PD21 pedal recovery force ~ PD22 ~= Accom mo clation E-9
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From page 406... ...
The significant correlations between the body posture and load implies the postural angles can be used as an effective indicator of the development of musculo-skeletal injuries as well. Observation of postural angles requires less specialized knowledge and has an easier calibration procedure than electromyography used to directly record a physiological estimate of load on relevant muscles (Aaras and Westgaard, 1988~.
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From page 407... ...
I Standard ~ riving Posture l | | Static Posture Dynamic Posture hip - :xion(oc)
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From page 408... ...
1. In this project, a hanging pedal is chosen for brake and accelerator pedals of the work station with a pedal arm length (P)
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From page 409... ...
l accelerator pedal length 1) 27.9 to 30.5 cm for a treadle pedal 14.0 cn (Van Cott and Kinkade, 1972; Woodson, ~ 98 ~ )
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From page 410... ...
3. Analytical Determination of Pedal Width and Foot Movement Time The lateral separation between the center-lines of the brake and accelerator pedals-foot movement amplitude (A)
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From page 411... ...
~ = As/N` 24 7 L ) Predict foot movement time using Drury's equation (1975)
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From page 412... ...
SMT = RMT/1.64 - The predicted single foot movement time (SMT) curves of three SAE population groups using Drury's equation are as follows: 0.18 0.16 ._ ~ _ 0 ~ 0.08 o o 0.06 a, 0.04 ._ U)
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From page 413... ...
Min. clearance between the pedals (Diffrient et al., 19811: 5.1 cm Half the width of brake pedal: 5.0 cm (need to be larger than the accelerator pedal width for a shorter foot movement time)
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From page 414... ...
4. Design Guidelines and Suggestions - A hanging pedal with a flat surface shape needs to have a pivot at the pedal plate to accommodate the different initial foot angles of each population from the floor: its pivot ranges are about 5 to 15 degrees depending on pedal plate pivot point height.
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From page 415... ...
1. Key Ergonomic Principles - Pecial plate horizontal angle from the floor (PD5~: Comfort and Force - Pedal plate lateral angle form the vehicle center-line (PD61: Comfort - Peclal plate pivot (P3)
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From page 416... ...
A.. Pedal Plate Pivot Pt Pedal Base Pivot Pt The pedal actuation angle (PD20)
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Max. (Van Cott and Kinkade, 1972)
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From page 418... ...
Pivot Pt 1~ ~ h on distance from Heel Pt to P3 i h on distance . from Hip Pt to P3 Pt h on distance from WO to P3 Pt J Pedal Plate Pivot Pt 2.
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From page 419... ...
Summary of Controversy on Pedal Configuration (rank: 1-more desirable, 2-moderately desirable, 3-less desirable) Brake-accelerator | Foot Movement time ~ Driving Safety | Design Suggestion ~ pedal configuration | l l l brake-above- 1 3 suggested accelerator coplanar l 2 | 2 | brake-below- | 3 | 1 accelerator l l l E-23
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From page 420... ...
(5) Suggest design guidelines on the pedal design parameters which accommodates the 5th percentile female to the 95th percentile male.
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From page 421... ...
deg. knee included angle (beta)
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From page 422... ...
:: :# ::. :: : : :~ :.::::_ I, ::::: I: :: : : , ': : 'I'd,: ' :::: .:: I: SRP ~= Heel Pt: Pedal Base Ball Pivot Pt of Foot 3:~4X ,^~~ ~.
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From page 423... ...
sin al +r2 sin a2+r3 sin a3 +r4 sin a4=r5 sin a5 where r! = hip joint height r2 = femoral link length r3 = shank link length + ankle height + heel height r4 = horizontal length from heel point to ankle joint r5 = horizontal length from hip joint to heel point al = 90 deg.
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From page 424... ...
* initial foot angle = ASIN (pedal plate pivot pt height / instep length)
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From page 425... ...
for kinematic analysis of the SAE 05% female where initial pedal plate pivot point height is 9.0 cm.
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From page 426... ...
) + ".dat" OPEN "a", #l, filenames FOR alpha= 0 TO 10 STEP .5 FOR beta = 95 TO 135 STEP .5 FOR gamma = 85 TO 110 STEP .5 · ~ Joint height 'alpha: horizontal angle of femoral link 'beta: included angle of knee joint 'gamma: included angle of ankle delta = alpha + beta - gamma '`delta: foot angle from floor rl = rc3 *
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From page 427... ...
E-IV: Pedal Design Synthesis NEXT beta NEXT alpha CLOSE #1 NEXT rc ~ E-31
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From page 428... ...
The foot movements are named "comfort foot movement zone" which designates the foot movements with comfort joint postures. Also the corresponding foot angles according to the horizontal distance from hip joint to ball-of-foot are plotted in the following chart.
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From page 429... ...
The foot movement charts depict the comfort movement zones increase gradually up to a certain hip joint height (about 38 cm in this example) and decrease sharply after that height.
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From page 430... ...
E-TV: Pedal Design Synthesis e 8 ~ _ 53k i.
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From page 431... ...
is assumed for complete pedal actuation) is plotted in the following chart using the kinematic simulation results.
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From page 432... ...
It is identifiec3 that the optimum hip joint locations are clependent on the initial P3 point height, pedal actuation requirement, and anthropometric population. The P3 point height and pedal actuation requirement determine the driving postures and foot rotation angle requirement of a certain population (see section TV-!
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From page 433... ...
E-IV: Pedal Design Synthesis 1HOC1Pt1{ Ball-oP 1 ll.lcm I lS.Scm 1 16.4cm I 5.Scm I agog I I I I I (Pll!
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From page 434... ...
have the horizontal adjustment of 17.0 cm ant! the vertical adjustment of 7.8 cm where initial P3 point height is 9.0 cm - the initial foot angle from the floor is 30 deg.
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From page 435... ...
WO - Workstation Origin (the point on the workstation platform underneath a seat reference point of SAE 50%; 3. APRP - Accelerator Pedal Reference Point.
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From page 436... ...
. - For ankle operated pedals in continuous use, such as an automobile accelerator' the maximum and minimum resistances should be less than those of leg operated pedals, such as a brake pedal (Van Cott and Kinkade, 1972)
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From page 437... ...
3.35.6 - 267 N (8-60 lb) (Van Cott and Kinkade, 1972)
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From page 438... ...
(1971) , Foot Forces Exerted at Various Aircraft Brake-Pedal Angles, Human Factors, 13, 445-456.
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From page 439... ...
J (l 993g, Human Factors in Engineering ancit Design 7th ea., New York, McGraw-Hill Book Company Schmidt, R
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