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Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

EM Introduction I. Introduction It. Ergonomic Considerations in Pedal Design Pedals Design Considerations brake pedal T - Need fast and error-fr~ e activation (speed and safety). - Locate within comfort angles of body movement (comfort reach/or posture). - Design a proper pedal resistance for the pedal actuation (strength requirement). - Be sure to accommodate the Sth-percentile female to the 95th | percentile male as she wn in SAE J833 (accommodation). l accelerator pedal - Need continuous operations during driving a bus. Range of operation of the pedal should be comfortable (comfort reach/or posture). - Deliver actuating forces effectively (strength requirement). - Be sure to accommodate the 5th-percentile female to the 95th | percentile male as shc wn in SAE J833 (accommodation). l ig Five ergonomic principles for the pedal design 1. Comfort of lower body posture, 2. Proper pedal actuating force. 3. Fast foot movement (speed), 4. Accurate pedal activation (safely), and 5. Accommodation of various percentiles of two different anthropometric populations - 5 percentile female to 95th percentile male. E-]

E-: Introduction I-2. Importance of Ergonomic Pedal Design Inappropriately designed brake and accelerator pedals might: 1. Cause musculoskeletal problems. => Holding a ciriver's foot at an awkwarc! angle on the pedals tires the driver overall, not just the driver's foot or ankle (Woodson, ~ 98 ~ ). 2. Cause undesirable pedal activation errors. => A large number of incidents have been reported in which a driver inadvertently depresses the accelerator when intending to depress the brake. This unintended! 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~. 3. Cause uncomfortable leg postures for small or large drivers to operate the pedals. 4. Need excessive leg or ankle forces for weak drivers to actuate the pedals. E-2

E-~: Literature Review Il. Literature Review I. 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.) | the farther the ball-of-fc ot travels. | constant distance The closer the fulcrum is to the heel, at the heel actuation (1.9 cm) | the smaller the ball-of-f lot travels. | 2. The speed and accuracy of discrete foot motions: Kroemer (1971) - Measures: speed and accuracy of foot motions After a short learning period, the subject could perform the task with considerable accuracy and with very short travel time (averaging about 0. ~ sec.). · The results strongly suggest the speed and accuracy of foot movements can be attained with practice. The pedal locations within a foot comfort zone will not significantly affect the speed and accuracy of foot movement. E-3

E-TI: Literature Review 3. The prediction of foot movement time: Drury (l 975) - Studier! on coplanar foot movements - pedals are in the sane plane. - Developed an equation to predict foot movement time. - foot movement time = f (task difficulty) = f (foot movement distance, pedal size, and shoe sole width) Used a modified equation of Fitt9s law by Welford (l 9681. - Drury's index of task difficulty (ID) D = logy-+ 0.5] where A = movement amplitude (distance) to centerline of target W = pedal width S = shoe sole width - Reciprocal (back-and-forth) foot movement time (RMT) RMT = 0. ~ 874 + 0.0854 x ID - Single foot movement time (SMT) SMT= RMT/1.64 - For noncoplanar pedals, movement time can be double. => Drury's equations are useful for predicting the effects of varying the width of a pedal and/or the distance between pedals on movement time. 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. The optimum angle was verified by asking the subjects to rate their ankle comfort at each angle; 80 % of the subjects preferred the optimum angle. E-4

Em: Literature Review 5. Design guidelines of a brake pedal depending on seat height: Woodson (1981) 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. Design I A high-seat h ight I Amid-position I Alow-seathe ght Parameters | (43.2 cmab ve) | seat height | (30.5 cmbel w) 1 brake pedal I l l configuration ~\/ ~f em brake pedal | 20deg.orl ss l 15-30deg. 1 30.deg.orrrore angle l l | brake pedal | 89 N (20 lb) ~ tax. | 178 N (40 lb) Max. 1 623 N (140 lb) Max. forces force downward and a little equally forward and mainly forward in a application | bit forward in a | downward in a | reversed curvili: tear direction straight line reversed curvilinear pattern pattern E-5

E-ITI: Analysis of Pedal Design Parameters Ill. Analysis of Pedal Design Parameters ITI-~. Pedal Design Variables 1. Accelerator and brake pedals used in a driver's work station neec! to be analytically characterized for a systematic design. 2. The following 14 dimensional attributes are utilized to clefine the design variables of the pe(lals: (~) length, (2) width, (3) depth, (4) diameter, (5) thickness, (6) curvature, (7) shape, (~) angle, (9) adjustment range, (10) location, (11) travel distance, (12) resistance, (13) control/response (CR) ratio, and (14) material property (You et al., 1 9951. 3. 26 pedal design variables are identified (see the table on next page). 4. The design variables are classified into three groups according to the following design characteristics: (~) ergonomic design variables (ED), (2) mechanical design variables (MD), and (3) aesthetic design variables (AD). Summary of Pedal Design Variables Pedal Component No. 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. E-6

E-~: Analysis of Pedal Design Parameters Taxonomy of Pedal Design Variables Pedal Design Variables pedal plate lengthpedal plate length width thickness shape angle ELF material pedal arm length width thickness shape material pedal length mounting width base thickness angle re;~:loe location material Code Classification PDl 1 ED PD2 ED PD3 MD PD4 ED PD5 ED PD6 ED PD7 ED PD8 ED Pug ED PDl0 ED PD11 ED PD12 MD PD 1 3 MD PD14 MD PD15 MD PD16 MD PD17 MD PD18 MD PD19 MD PD20 ED, MD PD2 1 ED PD22 ED PD23 MD PD24 MD PD25 MD PD26 MD pedal plate width pedal plate thickness pedal plate shape pedal plate horizontal angle from the floor pedal plate lateral angle from a vehicle center line P32 angle ranges horizontal distance of PPRPj from wo4 vertical distance of PPRP from WO lateral distance of PPRP from WO pedal plate material pedal arm length pedal arm width pedal arm thickness pedal arm shape pedal arm material pedal mounting base length pedal mounting base width pedal mounting base thickness pedal actuation angle pedal actuation force pedal recovery force ~. horizontal distance of PMBRP~from WO vertical distance of PMBRP from WO lateral distance of PMBRP from WO pedal mounting base material (Note) 1. Pedal Design; 2. P3 - Pedal Plate Pivot; 3. PPRP - Pedal Plate Reference Point, 4. 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. E-7

E-TIT: Analysis of Pecial Design Parameters Taxonomy of Pedal Design Variables Pedal 1 ~1 , ~1 ,~ Pedal Plate Pedal Arm Pedal Base ~ ~ ~ ~ .... Hi.. ~ ~ ~ ~ .. _engt 1 ~: Length Length Width . ~ . . .. I .. Width Width Thickness Thickness Thickness Shape Shape l~.,.,., Lo c.ation I . . ~.~.~ ~ , .,i ..~ .~. , I Hi. ... .. .. .... . . ... . . ... ... ~ ~ T ...... .. M;ateria'l:~.:: ~ . Wrangle .... . .... . . ~ : _ :: ::a i:: i: : i: : :::: : : . : ~.~-,~ ~es:lstance~. ~ . . ~ . : ~::~:~ I: ~ :~ -' :~ :::: Hi I: I: ~ ~ :~ ~ ~ JO .:,:: : : Location Material * The shaded boxes represent ergonomic pedal design variables. E-8

E-TIN: Analysis of Pedal Design Parameters Key Design Considerations Related to the Ergonomic Pedal Design Variables Be: related ergonomic design principle) Design Variables ~ Code ~Des gn Consideration Comfort Force Speed S afety . 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

E-~: Analysis of Pedal Design Parameters ITI-2. Standard Bus Driving Postures T. When establishing a standard driving posture, biomechanical (force), physiological (muscle strength), and anthropometric (range of motion of a body joint) characteristics of a human must be considered integratedly for comfortable posture and proper force application (You et al., 19954. 2. Postural angles has been used as an alternative method for quantifying the load on musculo-skeletal structures which leads the development of pain and discomfort in occupational work situations. 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~. . The comfort zones (see the table and figures on next page) are generally locater! in the middle between the extreme limits of limb movement, but modifications for vehicular seating are made to minimize the muscular load against gravity (Diffrient et al., 19814. 4. The angle of each body joint of the standard posture (see the table on next page) is determined on the basis of the comfort zones defined in ergonomic design sources (You et al., 1995~. The optimum knee angles for applying normal forces on pedals are ~ ~ 0 to 120 deg. (Diffrient et al., 198 I). The optimum angular relationship between the lower leg and the pedal surface should be approximately 90 deg. (SAE Il 100, 1994; Woodson, 1981~. The recommended seat pan angles to support comfortable upper leg postures are 5 to 25 degrees (Diffrient et al., ~ 98 ~ ). E-10

E-~: Analysis of Pedal Design Parameters Comfort ROMs and Standard Driving Postures of Lower Body (unit : deg.) . Joint Movement | Comfort ROM * I Standard ~ riving Posture l | | Static Posture Dynamic Posture hip - :xion(oc) I [95,120] 1 95 90 | hip at auction (it) | [-5, 20 ~ ~O 1 0 ~| | (for brake) (for accelerator) Rotation (leg twist) (X) | [-15,15] | 0 0 leg knee flexion (a) [95' 135] 115 120 (for idle pedal (for full pedal ~press) press) foot ~ankleflexion(sj I [85,l]0] | 90 110 l | | (idle pedal (for full pedal l | press) press) Abduction (is) | [0, 15] | 0 2 * ROM - Range of Motion E-11

E-IV: Pedal Design Synthesis IV. Pedal Design Synthesis IV-~. Pedal Plate Length (PDI) 1. Key Ergonomic Principles: Accommodation 2. Design Considerations · The pedal should be big enough so that both the SAE 05% female and the SAE 95°/O male driver can press the pedal with the ball of the foot. 3. Anthropometric Data Population | Shoe | Ball-o -foot | Required Foot Slippage of Ball | Length | to H eel I Rotation Angle of-Foot on l l (E ) I for 20 deg. Pedal Hanging Pedal i l l l I Actuation (F) ~(S) SAE 05% Female | 25.0 cm | 16.0 cm | 22.5 deg. 2.3 cm I SAE 50% 1 28.5 cm 1 18.0 cm 1 20.0 deg. 2.2 cm I SAE 95% Male 1 32.0 cm 1 20.0 cm 1 18.0 deg. 2.1 cm l Range | 7.0 cm | 4.0 am I N/A 0.2 cm (Note) 1. In this project, a hanging pedal is chosen for brake and accelerator pedals of the work station with a pedal arm length (P) of 18.0 cm and an actuation angle (A) of 20 deg. The required foot angle rotation (F) is determined by the following equation: 2. The slippage of ball-of-the foot on the pedal is determined by the following equation: r~- 5 = :[B sin(~- P sin(20°); + [{B - B COS(~} + { P - P cos(20°)}]2 'I ~ ~ - E-12 /

E-IV: Pedal Design Synthesis 4. Design Guidelines and Suggestions Design Variables | Design Guidelines ~ Design Suggestions brake pedal length 1) 7.6 cm Min. (Van Cott and 8.0 cm L I Kinkade, 1972) 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 ~ ) 2) 7.6 cm for a hanging pedal (Woodson, ~ 981 ) E-13

E-IV: Pedal Design Synthesis IV-2. Pedal Plate Width (PD2) 1. Key Ergonomic Principles: Speed, Safety, and Accommodation 2. Design Considerations Pedals with the maximum wicith matters little as long as there is enough clearance between adjacent pedals (Van Cott ant] Kinkade, ~ 972~. The brake ant} accelerator pedals must have a sufficient clearance in order to prevent an unintended pecial activation. 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) of SAE 50%- is determined by using the horizontal distance of ball-of-foot from hip point (R) of SAE 50 % (see section "TV-5. Pedal Plate Location") and the standard driving postures (see section "~-2. Standard Bus Driving Postures". The following equation shows the functional relationship between the parameters: A = R of SAE 50 NO x sin (hip abduction angle for accelerator pedal) - R of SAE 50 % x sin (hip abduction angle for brake pedal) = 73.8 x sin(10°) - 73.8 x sin(O°) = 21.7 - 8.9 = 12.8 cm ll~p.~Ib'l:; ` ,Wr AL ,\ (~.O`,t,\/`A'~n'~n' Dirtanc~) E-14 T T R(Ill~r Dim rrOn'rr.p 11. tin I:~llII-~,f-f~ I)

E-IV: Pedal Design Synthesis Population Horizontal Hpt [Lateral Hip Hip Hip Joint Distance from Distance Abduction Abduction for Travel | Opts to teal - | from SRP | for Brake | Accelerator | Angle (O of-foot (R) | (L) | Pedal (C()4 | Pedal (is): | SAE 05% 66.5 cm 8.4 cm 0.4 deg. i i.5 deg. ~ I.l deg. Female ~ SAE 50% ~ 73.8 cm ~8.9 cm ~0.0 deg. ~10.0 deg. 10.0 deg. SAE 95°/0 ~.~ cm 9.3 cm - 0.3 deg. 8.8 deg. 9.~ deg. Male ~I (Note) I. Hpt - Hip Joint Point 2. The determination of the Hpt to ball-of-foot of each population group is presented in detail in section "TV-5. Pedal Plate Location." 3. SRP - Seat Reference Point 4. ~ =AS/Nt 8 OR t) s. ~ = As/N` 24 7 L ) Predict foot movement time using Drury's equation (1975) - Drury's index of task difficulty (ID) ID = logy W S + 0.5] where A = foot movement amplitude (distance) to centerline of target W = pedal width S = shoe sole width Population ~ Horizontal Hipioint ~ Foot ~ Shoe 'I Distance from Hpt Travel Angle Movement Width ~ to ball-of-foot(R) ~(H) ~ Distance (A) ~ ~(S) SAE 05% Female 1 66.5 cm I ~ 1. ~ deg. ~12.86 cm ~9.0 c SAE 50% ~73.8 cm | 10.0 deg. ~12.86 cm ~10.3 c SAE95%Maie ~81.! cm I 9.] cdeg. 1 12.87 cm 1 11.6c~ (Note) I. ~4 = 2R sin(2 - 3 E-15

E-IV: Pedal Design Synthesis - Reciprocal (back-and-forth) foot Movement Time (RMT) RMT = 0. ~ 874 + 0.0854 x ID - Single foot Movement Time (SMT) 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) 0.14 0.12 0.1 0.02 o O SAE 05% ,'< SAE 50% 0 SAE 95% 0 1 2 3 4 5 6 Pedal Width (unit: cm) 8 9 10 The predicted SMT curves indicate that the pedal width (over a reasonab range), with typical spacing between pedals, has only a minimal effect on movement time (40 msec at most - 0.6 m for stopping distances with travel at 56.3 km/in t= 35 mph]~. Reaction time must be added to the movement time to obtain overall performance time estimates of foot movement. E-16

E-IV: Pedal Design Synthesis The lateral distance between the brake and accelerator pedals (12.8 cony consists of half the width of brake pedal (5.0 cm), the spacing between the pedals (5.] cm), and half the width of accelerator pedal (2.7cm). 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). Half the width of accelerator pedal: 2.7 cm Predicted foot movement time for the suggested pedal widths assuming the pedals are located on the same plane. For the noncoplanar pedals, the movement time will be doubled (Drury, ~ 975~. Population ~ SMT for Brake P dal | SMT for Accelerator Pedal ~ | (W= 10.Ocmt | (W=5.4cm) l SAE 05% Female | 127 msec | 139 msec l SAE 50% l 124 msec 1 135 msec l SAE 95% Male 1 121 msec | 131 msec 4. Design Guidelines and Suggestions l Design Variables | -~Design Guidelines | Design Suggestions | lateral distance of BPRP' | 8.9 cm (Diffrient et al., 1981) | 8.9 cm l from Wo2 (PD10) l l | lateral distance of APRP ~| 17.8 - 20.' cm (Woodson, 1981) | 21.7 cm from WO (PD10) ~ brake pedal width 10.2 cm Optimum; 10.0 cm ~ 7.6 cm Min. (Diffrient et al., ~ )81) ~ accelerator pedal width 8.9 cm Optimum; 5.4 cm 5.1 cm Min. for treadle pedal (Diffrient et al., 1981) spacing between the pedals ~ 5.1 cm Min. (Diffrient et al., 1 )81) 1 5.1 cm (Note) 1. BPRP - Brake Pedal Reference Point 2. WO - Workstation Origin (the point on the workstation platform underneath a seat reference point of SAE 50%; 3. APRP - Accelerator Pedal Reference Point E-17

E-IV: Pedal Design Synthesis IV-3. Pedal Plate Shape (PD4) T. Key Ergonomic Principles: Accommodation 3. Design Considerations The pedal shape can be square, rectangular, circular, or oval as long as it is flat and affords enough area of contact with the shoe (Van Cott and Kinkade, ~ 9721. A small curved pedal will make an equally satisfactory accelerator control (Woodson, 1981). Anthropometric Data . Population Ball-of-foot to Pedal Plate Pivot Point Height (P) Heel Point (B) 6.16 cm 9.0 cm SAE 05% Female 16.0 cm 22.5 deg. 34.0 deg. SAL 50% 18.0 cm 20.0 deg 30. 0 deg SAE 95% Male 20.0 cm 17.9 deg. 26.5 deg. Range 4.0 cm 4.6 deg. 7.5 deg. 1 1.57 cm 46.0 deg. 40.0 deg 35.0 deg. 11.0 deg. Initial Foot Angles (F) (Note) 1. Initial Foot Angles (F) = A SIN (-B) 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. - The curvature of a pedal with a curved surface should be determined on the basis of the differences of the initial foot angles. E-~8

E-IV: Pedal Design Synthesis IV-4. Pedal Angles (PDS, PD6, PD7, and PD20) 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) angle ranges (PD71: Comfort and Accommoclation - Pedal actuation angle (PD20~: Comfort 2. Design Considerations - The initilal angle (nonactive) of the pedal must not be too steep; otherwise, the driver's ankle tires easily (Woodson, 1981~. - The driver should always be able to rest his or her heel on the floor while holding or depressing the pedal (Woodson, 1981~. 3. Analytical Determination of Pedal Angles - The pedal angles are determined on the basis of the standard driving postures assumed in this study (see section "TTI-2. Standard Driving Postures". - The pedal plate horizontal angle from the floor (PD5) is determined by the geometry of the hip, knee, and ankle angles (see the figure on next page). pedal plate hor. angle (PD5) = thip flexion (a) - 90:1+ knee flexion (~) - ankle flexion (~) = 30 deg. (= 95 - 90 + ~15 - 90) for idle press = JO deg. (= 90 - 90 + ~20 - ~ ~ 0) for full pedal press E-i9

E-TV: Pedal Design Synthesis hip.flexio'2 SRP knee fiexi~i ankle Bal' Pivot Pt pedalplale Pedal Plate her. angle Pivot Pt - The pedal plate lateral angle off the vehicle center line (PD6) is determined by the geometry of the hip and ankle angles. pedal plate lateral angle (PD6) = hip abduction (,8) + hip rotation (X) + ankle abduction (o) = 0 deg. (= 0 + 0 + 0) for the brake pedal = 1 2 deg. (= 0 + ~ 0 + 2) for the accelerator pedal pedal actuation - pe~lalplate angle \ lateral angle pedal plate h on angle it. ,. A.. Pedal Plate Pivot Pt Pedal Base Pivot Pt The pedal actuation angle (PD20) is determined by both a pedal arm length and a allowed foot travel angle for full pedal press. In this study, the pedal arm length is assumed to be equal to the length of heel to ball-of-foot of SAL 50% ~ ~ 8.0 cm). This will be described in detail in section "TV-5. Pedal Plate I,ocation." The determination of the pedal plate pivot angle ranges (PD7) is cliscussed in section"IV-3. Pedal Plate Shape." E-20

E-IV: Pedal Design Synthesis 4. Design Guidelines and Suggestions Design Variables l Design Guidelines I Desigr I | Suggesting brake T pedal plate orizontal angle | l. 45 deg. (?; Compton, 1 45 deg l pedal | | 1994) l 2. 25 - 35 deg. (Hertzberg l | end Burke, 1971) | pedal plate: literal angle | 1. 5 deg. ( ? ) I 0 deg l | 2. 12 deg. for treadle pedal | l l | (Compton, 1994) | pedal actual an angle | 1.25 deg. (?) | 20 deg accelerator l pedal plate orizontal angle 1 1. 42 deg. ( ? ) I 30 deg pedal | 2.15 - 30 deg. (Woodson, I 1981) 3. 45 deg. for treadle pedal l | (Compton, 1994) l | pedal plate ] rteral angle | 1. 12 deg. for treadle pedal | 12 deg 1 1 (?; Woodson, 1981; 1 l | Compton, 1994) l |P3 angle ranges l | 10deg | pedal actual an angle | 1. 20 deg. (?) | 20 deg 2. 10.0 deg. Optimum, 15 deg. Max. for treadle pedal (Diffrient et al.' 1981) 3. 5.1 cm Max. travel displacement; 30 deg. Max. (Van Cott and Kinkade, 1972) E-21

E-IV: Pedal Design Synthesis IV-5. Pedal Plate Location (PDS, Pug, and PDIO) i. Key Ergonomic Principles: - horizontal distance of P3 Pt * from WO (PD8~: comfort and accommodation P3 Pt: Pedal Plate Pivot Point; the P3 Pt is used interchangeably with PPRP (Pedal Plate Reference Point) in this study} · vertical distance of P3 Pt from WO (PD9~: comfort, force, speed, safety, and accommodation - lateral distance of P3 Pt from WO (PDIO): comfort, speed, and accommodation (the lateral distance of P3 Pt is discussed in section "IV-2. Pedal Plate Width") If: Hip Pt Height WO / (Workstation Origin) SRP Sew Height i, . __ _ _ - : . Ball of Foot / Pedal Base ' ~! 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. Controversy on the Relative Location of Brake and Accelerator Pedals - :[n most automobiles, the accelerator is lower than the brake pedal, thus requiring the lifting of the foot from the accelerator, its lateral movement, and then the depression of the brake. Glass and Suggs (1977) reported that when the brake E-22

E-IV: Pedal Design Synthesis was even with or above the accelerator, several subjects caught their foot on the edge of the brake pedal during upward movement from the accelerator. - Glass and Suggs (1977) found that movement time was optimum when the brake was 2.5 to 5.1 cm below the accelerator. In this configuration with the accelerator partially depressed, one could merely slide the foot to the brake without lifting it. - Casey and Rogers (1987) point out that inadvertent activation of the accelerator is more likely with coplanar pedals. - Schmidt (1989) mentioned that the "runway car" phenomenon in which drivers experience a sudden and unexpected acceleration was due to "insufficient height differential between brake and accelerator pedals" and the drivers actually having their foot on the accelerator rather than the brake. Woodson (1981) recommended that the pedals should be approximately the same level so that the driver does not have to raise his or her foot very high in order to keep from catching a toe on the adjacent pedal. 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

E-IV: Pecial Design Synthesis The "brake-above-accelerator" pedal configuration was chosen in this project. This pedal configuration may require longer foot movement time for braking than those of the other pedal configurations. Using the equation of Drury (1975), it was estimated that the extra foot movement time would be 130 see (~.95 m for stopping distances with travel at 56.3 km/in (30 mph): see section "IV-2. Pedal Plate Widths. 3. Analytical Determination of Pedal Location Using Kinematic Simulation 3.! Objectives ( l ~ Develop a kinematic mode! of seat-pedal relationship. (2) Identify the geometric relationships between driving postures, anthropometric variables, and pedal design parameters. (3) Simulate foot movements (pedal plate trajectories) under postural constraints using the kinematic model. (4) Find an optimum relative seat-pedal location of a certain population (the 5th percentile female, 50th percentile, and 95th percentile male presented in SAE 1833) based on the kinematic simulation. (5) Suggest design guidelines on the pedal design parameters which accommodates the 5th percentile female to the 95th percentile male. E-24

E-IV: Pedal Design Synthesis 3.2 Anthropometric Data and Postural Constraints 3.2.1 Anthropometric Data An bat ~ ,~ En= ~ ariab e SAE 05°/O Female SAE 50°/O femoral link length (r2) 36.2 cm 40.7 cm shank link length 35.1 cm 39.S cm ankle height 7.8 cm 8.6 cm heel height 2.5 cm hor. length from heel 6.8 cm 7.8 cm point to ankle joint (r4) hor. length from ankle 9.2 cm 10.2 cm joint to ball-of-foot instep length with shoes 16.0 cm 18.0 cm SAE 95°/O Male 45.2 cm 44.5 cm 9.4 cm 8.7 cm 1 1.3 cm 20.0 cm Hip Pt-' ~2lpJiexion L.~:: ~! SRP knee flexion shank link ankle height with shoes ankle Ball flexion of Foot , ~ ~! ~ ,! ~ ~ . ~ ~ ~ 7\ ~ _ length 3.2.2 Postural Constraints based on Comfort Driving Postures - The optimum angular relationship between the lower leg and the pedal surface should be approximately 90 deg. (SAE J1 100, 1994; Woodson, 1981). _ Comfort ROMs hor. angle of femoral link (alpha) [0, 1 0] deg. knee included angle (beta) [95, 135] deg. ankle included and e Annual [85, 1 10] deg. _ f ~[0, 60] deg. E-25

E-IV: Pedal Design Synthesis 3.3 Kinematic Modeling of Seat-Pedal Relationship The following assumptions were made on the human body, seat, and pedal for kinematic modeling: Assumptions 1. human body: (1) fixed link length; (2) pin joint connection. 2. hip point: no sliding on the seat pan. 3. heel point: (1) always on the floor while holding or depressing the pedal, (2) can be sliding on the floor. 4. seat pan: (1) horizontal angle = 5 deg.; (2) no seat pan angle adjustment. 5. pedal system: (1 ) pedal plate has a pivot; (2) no adjustment of pedal base pivot point. A. ~ ~ . --~..~.~1.~1.~:.~ ~ ~ ...... .~ ~ . I. . :: :# ::. :: : : :~ :.::::_ I, ::::: I: :: : : , ': : 'I'd,: ' :::: .:: I: SRP ~= Heel Pt: Pedal Base Ball Pivot Pt of Foot 3:~4X ,^~~ ~. . hi. . river al 3.4 Vector Loop Approach for Kinematic Analysis 3.4.1 Vector Loop Approach For the kinematic analysis of seat-pedal relationship, 'vector loop' method was employed in this study. The steps of the vector loop approach are as follows: E-26

E-IV: Pedal Design Synthesis Step I. Attach to the links vectors forming a closed loop. Step 2. The vectors are defined in terms of lengths ant} angles. Step 3. Write the vector-Ioop equation stating the sum of the vectors zero. Step 4. Break the vector-Ioop equation into two scalar (X, Y) component equations. Solve the position unknowns. in the loop is 3.4.2 Vector :Loop and Equations of Seat-Pedal Relationship Vector Loop: Hip Pt r~2 r1 be 3 a2=alpha \j n a1 Pedal Plate Pedal Base Pivot PI Pivot Pt Vector game,_ L°°P ~\~Vector '~delta Loop 2 Heel Pt r5 rl + rim + r3 + r4 = r5 r! cosal +r2cosa2+r3 cosa3 +r4cosa4=rScosa5 r! 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. a2 = alpha (horizontal angle of femoral link) a3 = ~ 80 + alpha + beta (knee included angle) a4 = gamma (ankle included angle) + delta (foot angle from the floor) a5 =0 delta = alpha + beta - gamma (constants: r2, r3, r4; unknowns: rl, r5, alpha, beta, gamma) E-27

E-IV: Pedal Design Synthesis 4. Kinematic Simulation 4. ~ Initial Pedal Condition and Constraints 4.1.1 Foot Rotation Angle Requirement - foot rotation angle requirement = f (pedal actuation angle, pedal level length) - In this project, a hanging pedal is chosen for brake and accelerator pedals of the work station with a pedal arm length (P) of 18.0 cm and an actuation angle (A) of 20 deg. The required foot angle rotation (F) is determined by the following equation: F = P A where B: instep length B Instep Length (B) Foot rotation angle Population (Heel-point to requirement (F ) ball-of-foot length) for 20 deg. pedal actuation SAE 05% Female 16.0 cm 22.5 deg. SAE 50% 18.0 cm 20.0 deg. SAE 95% Male 20.0 cm 18.0 deg. 4.1.2 Initial Pedal Plate Orientation and P3 Height - pedal plate orientation = initial foot angle = f (P3 point height) Pedal Plate Pivot | Pedal Plat/ Orientation (Initial Foot Angle) _ ~ SAE 50% . ~ 22.5 deg. 20.0 deg O O ::m 34.0 deg. 30.0 deg 5~ cni 46.0 deg. 40.0 deg SAE 95% Male 17.9 deg. 26.5 deg. 35.0 deg. * initial foot angle = ASIN (pedal plate pivot pt height / instep length) E-28

E-IV: Pedal Design Synthesis 4.2 Foot Movement Simulation Since the kinematic equations of the seat-pedal relationship formulated in section 3.4.2 are indeterminate, iterate the values of the unknowns associated the seat and joint postures as follows: 1. hip joint height (rI) from 30.0 cm to 60.0 cm, 2. horizontal angle of femoral link (alpha) from 0 to ~ O Leg., 3. knee included angle (beta) from 95 to 135 deg., and 4. ankle included angle (gamma) from 85 to ~ ~ 0 deg. to identify the corresponding foot movements, such as ~ . the location of heel point (rS) and 2. the foot angle from the floor (delta). On the next page is the sample program (programmed in Quick Basic code) for kinematic analysis of the SAE 05% female where initial pedal plate pivot point height is 9.0 cm. E-29

E-IV: Pedal Design Synthesis SAE05.BAS: QBASIC Program for Kinematic Simulation of SAE 5 °/O Female rc2 = 36.2 'femoral link length 'shank link length + ankle height + heel height rc4 = 6.8 'horizontal length from tree' point to ankle joint rc6 = 9.2 'horizontal length from ankle joint to ball of foot FOR rc! = 30 TO 60 f~lename$ = "c:\yhc\saeO5" + I,TRIM$(STR$(rcl)) + ".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 * SING - alpha - beta) * 3.14152/ 180) + rc4 * SIN((l80 - delta) * 3.14152 / 180) - rc2 * SIN(alpha * 3.14152 / 180) 'hip joint (Hpt) height r5 = rc2 * COS(alpha * 3.14152 / 180) + rc3 * COST - alpha - beta) * 3.14152/ 180) + rc4 * COS(~180 - delta) * 3.14152/ 180) 'horizontal distance from Hpt to tree' IF (rcl - .5) <= rl AND rl <= ret THEN IF delta >= 0 THEN foot = (rc4 + rc6) * SIN(delta * 3.14152 / 180) IF foot <= 9! THEN 'ball of foot HipNprp = r5 + (rc4 + rc6) * COS(delta * 3.141592 / 180) 'horizontal distance from Hpt to ball of foot PRINT #1, USING "##.# ###.# ###.# ###.# ##.# ##.# #.# ##.#"; alpha; beta; gamma; delta; rl; r5; foot; HipNprp END IF END IF END IF NEXT gamma E-30

E-IV: Pedal Design Synthesis NEXT beta NEXT alpha CLOSE #1 NEXT rc ~ E-31

E-TV: Pedal Design Synthesis The kinematic simulation generated output files whicli contains foot angles from the floor under the given postural constraints and conditions. The following chart illustrates the possible foot movement angles of the SAL 05% female along horizontal heel location from hip joint (the heel is always on the floor) maintaining comfortable joint postures where the pedal plate pivot (P3) point height is fixed as of 9.0 cm and the hip joint height from floor (rl) is 38 cm. The foot angles decrease as the heel locates farther from the hip joint. 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. 40 _ Comfort Foot Movemelit gone Population: SAE05% H p Joint Height 38 cr v . _ 48 52 56 60 64 68 72 76 80 HoreontaJ thence from Hp Joint to Heed (unit cm ) Comfort Foot Movement Zone 40 Spurn: SAE05% Hp Jo~ Hit 38 30 ~ 81 1 _ : , 20' _ _ ~ 413! ~ 'go_ ~10_ ~ _ 0 0 60 64 68 72 76 80 84 88 92 96 100 Horizontal Distance from Fop -1oint to Ball of Foot (unit:cm ~ Comfort foot movement zones where the initial P3 Pt height is 9.0 em E-32

E-TV: Pedal Design Synthesis The charts included on next page shows the comfort foot movements zones resulted via the kinematic simulation where the hip joint height varies from 30 to 60 cm. Only the comfort foot movement zones can be made at the hip joint heights from of 30 cm to 42cm. 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. This implies that there is an optimum hip joint height which provides the largest foot movement zones of a certain population. The comfort movement angles depending hip joint height and population group are depicted in the following chart. This chart verifies the above implication on an optimum hip joint height of a certain population with regard to the magnitude of comfort foot movement range. The chart indicates that the optimum heights are 38 cm for SAE 05°/O female, 43 to 47 cm for SAE 50%, and 49 to 50 cm for SAE 95 TO male. 30. 0 _ . . ... . .... . 25.0 .u _ it, ~ 20.0 ° ~ 15.0 · - _ ~ ° ~ 10.0 o O 50 c' 0.0 L SAE 05% . I SAE 50% I , [38] , lA3 ~ i' AN 28 32 36 40 44 48 52 56 Hip Joint (Hpt) Height (unit: cm) Variability of comfort movement ranges according to hip joint height (where the initial P3 Pt height is 9.0 cm) E-33

E-TV: Pedal Design Synthesis e 8 ~ _ 53k i. Ed ~0 - T_1' ~ ' E ~ , Fed 1 ~ ASH ''1 ~ ·~& o o ~ .* _ e! l ! 5 'ail Phi 1', 1 hi ~. ~ 8 _ ~ _ S. _ D., It ~ te n1 1 D' 1 e' 3 ;t al ~ e' I S .' ! . l Be g 8 Sit · _e i 1 T ~ 8 5 t - . ~ | S ~ 8's ~ de E-34

E-IV: Pedal Design Synthesis The determination of an optimum hip joint height was further investigated by relating the pedal actuation constraint and heel allowance range. The ranges of the heel locations which satisfy the pedal actuation constraint (in this study, 20 deg. is assumed for complete pedal actuation) is plotted in the following chart using the kinematic simulation results. The heel movement range signifies a postural allowance in this context; the zero tree! movement range means that a heel point needs to be at a specific location for the pedal actuation requirement. By combining the comfort movement zone size and the postural allowance, an optimum hip joint height of each population can be suggested. In this example, the optimum heights are 38 cm for the SAE 05% female, 43 to 44cm for the SAE 50%, and 49 cm for the SAE 95% male. 5. 0 _ . , ~, . . . . . 4.0 3.0 2.0 1.0 rat.- , ~ SAE 05% SAE50% ' SAE95% . ._ : :[49] . . [43-44] : / If: ~ '.1 ~ ,$ | ~ t ~ _ _ _ OF _ 1 ~ , 1 ., IN · , . 28 32 36 40 44 48 52 Hip Joint (Hpt) Height (unit: cm)

E-IV: Pedal Design Synthesis 5. ~ Simulation Results 5. ~ . ~ Optimum Hip Point Location Utilizing the concepts discussed above for the determination of an optimum hip point location of a population, the simulation results are summarized in the table below. 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-! and EV-3~. Optimum hip point location = f (driving postures, foot rotation angle requirement) = f (P3 Pt height, pedal actuation constraint) P3pt Height Design Variables Population 1 . . 1 SAE05% F SAE50 % Range SAE95 % M 6.16 cm Hpt to Heel pt . Heel Pt to Ball-of 44.6 cm 50.0 cm 54.5 cm 9.9 cm 14.8 cm foot 16.9 cm ~ 9.0 cm 4.2 cm ~-Li :: .. .. ................................................................... :::::::::::::::::::::::::::::::::::::::::::::::::::: :::::::::::::::::::::::::::::::::::::::::::::::::::::: :::::::::::::::::::::::::::::::::: ,.,,. ~,., ,, ~.......... ......................................................................................................... ......................................................................... ................................................................... 9.0 cm Hpt to Heel pt 53.2cm 58.2 cm 63.2 cm lO.Ocm Heel Pt to Ball-of foot 13.3cm 15.6cm 7.9 cm 4.6 cm 1.57 cm Hpt to Heel pt 61.Icm E-36 66.Icm 70.9 cm 9.8 cm

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!<l~lPlll,tl~l!~;l~l~. 1 1 1111~.~.~1131S I? !!T~!lll III!l~l0# 11l~!l~ ~llf'l~ll~:~!~l~Il~l!l~l~l~lllll!!il amp I Egg?

E-IV: Pedal Design Synthesis 5.1.2 Optimum Seat Reference Point Location In order to provide the optimum hip joint locations with the SAE 05% female to SAE 95% mate, the seat needs to be adjusted sufficiently. The following table shows that the seat shoulc! 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. Conversely, the optimum pedal location can be determined using the simulation results of SRP to P3 point of SAE 50% (86.6 cm with the initial P3 point height of 9.0 cm). seat adjustment ranges = f (variations of optimum hip point location, variations of hip pt to SRP) P3 pt Height 6.16 cm Design Variables Hpt Height Hpt to Seat Range SAE 05% F Population SAE 50 % SAE 95 % M 40.0 cm 45.0 cm 49.0 cm 6.4 cm 8.0 cm 9.6 cm 9.0 cm 3.2 cm Hpt to P3 pt Hpt to Buttock 59.4 cm 11.6 cm 9.0 cm 1 1.57 cm Hpt Height Hpt to Seat 38.0 cm 6.4 cm 66.9 cm 12.8 cm . ~cm~.~ :::::::::::::::::::::::::::::::::::::::::::::::::::: ................................................. 43.0 cm 8.0 cm 73.5 cm 141 cm 49.0 cm 9.6 cm 2 4 cm 11.0 cm 3.2 cm Hpt to P3 pt Hpt to Buttock 66.5 cm 11.6cm Hpt Height 33.0 cm E-38 73.8 cm 12.8 cm ........ ................ ..~..~ ~ --I- ........ 40.0 cm 81.1 cm 14.6 cm 2.4 cm 46.0 cm 13.0 cm

E-IV: Pedal Design Synthesis To Set ~ 6.4 cm ~ 8.0 cm ~ 9.6 cm ~3.2cm ' . " ' ' ""'"" ' ' ''' ' . ,.,. . .......... , . . ......... . ,. ., ,., ' ' '''''':"'"' ............................ ............................. .................................................................................................. .................................................. , ,. ,. Hptto P3 Pt ~ 72.2 cm ~ 79.9 cm ~87.3 cm ~15.1 cm Hptto Bu tock ~ 11.6 cm ~ 12.8 cm ~14.0 cm ~2.4 cm $ p - .................................. '''' ' ........................ ..... ................... ..................................... .............................. 6. Design Guidelines and Suggestions Design Variables | Design Suggestions brake | horizontal d: stance of BPRPt from WO' | 86.6 cm pedal ~ vertical Lists nce of BPRP from WO ~1 1.57 cm | lateral distal ce of BPRP from WO | 8.9 cm accelerator ~ horizontal d stance ofAPRP~ from WO ~86.6 cm pedal | vertical dish nce of APRP from WO ~9.0 cm lateral distance of APRP from WO 21.7 cm (Note) 1. BPRP - Brake Pedal Reference Point; 2. WO - Workstation Origin (the point on the workstation platform underneath a seat reference point of SAE 50%; 3. APRP - Accelerator Pedal Reference Point. E-39

E-IV: Pedal Design Synthesis IV-6. Pedal Plate Material (PDI 1) 1. Key Ergonomic Principles: Safety 2. Design Guidelines and Suggestions · The pedal surface material should provide a driver's foot with sufficient friction to prevent an undesirable slip of the foot on the pedal. IV-7. Pedal Resistance (PD21 and PD22) . Key Ergonomic Principles: Force and Accommodation 2. Design Considerations · The minimum resistance should be greater than the exerted force on the pedal by the weight of the leg alone. The pedal should return to its initial position when the driver release the pedal. This elastic resistance also reduces the possibility of undesirable activation caused by accidental contact with the pedal (Sanders and McCormick, 1993). - 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). - Maximum pedal resistance should never exceed the maximum force exertable by the weakest operator (Van Cott and Kinkade, 1972~. For frequently but not continuously used leg-operated pedals, a force of about 30°/O of the maximum exertable is reasonable (Van Cott and Kinkade, 1972). E-40

E-IV: Pedal Design Synthesis 3. Design Guidelines and Suggestions Design Variables | Design Guide lines | Design Suggestions brake pedal resistance | 1.232.6 N (52.3 lb) Ma>. (Diffrient et | 66.8 - 155.8 N (leg-operated pedal) al. ~ 1981) (15 - 35 lb) 2. 178 N (40 lb) Max. for a mid-position seat (Woodson, 1981) 3.35.6 - 267 N (8-60 lb) (Van Cott and Kinkade, 1972) accelerator pedal | 1.28.9-40N(6.5-9lb Optimum; 1 31.2-40N resistance 44.5 N (10 lb) Max.; (7 - 9 lb) (ankle-operated pedal) 26.7 N (6 lb) Min. (Diffrient et al.' 1981). 2. 17.8N(4lb)Min.; 28.9 - 40 N (6.5 - 9 lb) (Van Cott and Kinkade, 19721. E-41

E-IV: Pedal Design Synthesis References Aarast, A., and Westgaard, R. H. (1988), Postural Angles as an Indicator of Postural Load and Muscular Injury in Occupational Work Situations, Ergonomics, 31 (6), 915- 933. Ayoub, M. M., and Trombley, D. J. (1967), Experimental Determination of an Optimal Foot Pedal Design, Journal of Industrial Engineering, ~ 7, 550-559. Casey, S., and Rogers, S. (1987), The Case Against Coplanar Pedals in Automobiles? Human Factors, 29 (1), 83-86. Compton, T. (1994), Driver Workstation Upgrade on Metro Transit Buses, Seattle, WA, Municipality of Metropolitan Seattle. Davies, B. T., and Watts, I. M., Ir. (1970), Further Investigations of Movement Time Between Brake and Accelerator Pedals in Automobiles, Human Factors, 12 (6), 559-561. Diffrient, N., Tilley, A. R. and Harman, D. (1981) Human Scale 7/8/9, The MIT Press. Drury, C. (1975), Application of Fitt's Law to Foot-Pedal Design, Human Factors, 17, 368-373. Glass, S., and Suggs, C. (1977), Optimization of Vehicle-Brake Pedal Foot Travel Time, Applied Ergonomics, 8, 215-218. Hertzberg, H. T. E., and Burke, F. E. (1971), Foot Forces Exerted at Various Aircraft Brake-Pedal Angles, Human Factors, 13, 445-456. Kroemer. K. H. E. (1971), Foot Operation of Controls, Ergonomics, 14 (3), 333-361. Morrison, R., Swope, I., and Halcomb, C. (1986), Movement Tinge and Brake Pedal Placement, Human Factors, 28 (2), 241-246. Mortimer, R. G. (1974), Foot Brake Pedal Force Capability of Drivers, Ergonomics, 17 (41. Oborne, D. I. (1987), Ergonomics at Work, John Wiley & Sons Proctor, R. W., and Van Zandt, T. (1994), Human Factors in Simple and Compl:ex Systems, Allyn & Bacon. E-42

E-IV: Pedal Design Synthesis SAL (1994), 1994 SEE Handbook, vol. 3, Warrendale, PA, Society of Automotive Engineers Incorporated. Sanders, M. S. and McCormick, E. J. (l 993g, Human Factors in Engineering ancit Design 7th ea., New York, McGraw-Hill Book Company Schmidt, R. ~ ~ 989), Unintended Acceleration: A Contributions, Human Factors, 3 ~ (3), 345-364. I ~ Review of Human Factors Snyder, H. (1976), Braking Movement Time and Accelerator-Brake Separation, Human Factors, ~ 8, 201-204. Van Cott, H. P., and Kinkade, R. G. (1972), Human Engineering Guide to Equipment Design, Washington, DC: U.S. Government Printing Office. Woodson, W. E. (1981), Human Factors Design Handbook, New York, McGraw-Hill Book Company. You, H., Bucciaglia, I., Lowe, B., Gilmore, B. I., and Freivalds, A. (1995J, Bus Operator Workstation Evaluation and Design Guidelines: An Ergonomic Design Process for a Transit Bus Operator Transportation Institute. Workstation, PTT 9523, The E-43 Pennsylvania

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