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Kenneth W. Kennedy, Ph.D.
Aerospace Medical Research Laboratory
Wright-Patterson Air Force Base, Ohio 45433-6573

July 1978

ABSTRACT: "This report contains descriptions of the outer and inner boundaries of the 5th, 50th, and 95th percentile grasping-reach envelopes of men and of women. The reach envelopes are intended to guide the placement of critical hand operated controls for the seated operating and working body positions. The most important envelope is the 5th percentile, since it describes that past which 95 percent of the using population can reach. Thus, a controller located at the boundary of this envelope can be reached by an equivalent percentage of the male or female adult populations. A critical review of previous investigations of arm reach and a description of the Aerospace Medical Research Laboratory's Grasping-Reach Measuring Device  are presented. The data-gathering procedures and the methods of analyses are included. Applications of the data are also discussed. Data are presented in both graphic and tabular form. Vertical (X-Z) and (Y-Z) planes, and horizontal (X-Y) planes through the various percentile envelopes are presented.

Appendices are included, reporting (1) comparisons between original and final data, (2) reach envelopes for a 50/50 mixed adult male and female using population, and (3) anthropometric data on subject populations."


Eighteen sources are reviewed.

APPARATUS: "To derive information on reach capability, the Aerospace Medical Research Laboratory Reach and Strength Measuring Device was used. It includes a rotatable hard seat mounted on a platform beneath an arch so that the Seat Reference Point (SRP) of the seat lies in the plane of the arch. . . . One side of the arch contains friction held measuring rods radiating at 15 intervals, so that each points to the center of the arch. Each rod is calibrated to indicate the distance from the center of the arch to the mid-point of the knob at the inside ends of the rods. . . . The seat's axis of rotation runs vertically through its SRP and the center of the arch. the SRP is 24 inches . . . below the center of the arch. . . . This design permits the subjects to push the scaled rods along lines radiating from the shoulder level, regardless of the orientation of the seat. . . .

Two large button switches, lightly spring-loaded, were installed in the back of the seat, 18 inches above SRP and 3 inches to the right and left of the seat-back centerline. When the subject is seated, the weight of [the] back against the switches energizes two lights at his feet. . . . Should a light . . . go off during reach measurements, the subjects know they are out of position and must repeat the measurement.  The right light is the most important, since all reaches are made with the right hand. The lights function as a warning, primarily during establishment of the forward and left sectors of the reach envelope, when loss of contact between the subject's back and the seat back is most likely to occur." 

Reach capability obtained with the use of the back switches is intended to be equivalent to Reach Zone 1, as defined in Mil Std 1333, Aircrew Station Geometry for Military Aircraft, 9 January 1987.

Measurements were taken throughout vertical planes at 15 intervals from that corresponding to the mid-sagital plane, or 0.

"Twelve anthropometric dimensions were measured on each subject. These are listed below.

                              Age                                             Acromion Height, Sitting
                              Height                                        Buttock-Knee Length
                              Weight                                       Biacromial Diameter
                              Functional Reach                   Shoulder Breadth
                              Sitting Height                           Shoulder-Elbow Length
                              Eye Height, Sitting                  Forearm-Hand Length

The means and standard deviations for these dimensions, as well as comparable data from military and civilian populations are given . . .."

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