154 



PANEL DESIGN 



displays on a panel have the same optimal 

 position, the more important and more fre- 

 quently used items should be given the pre- 

 ferred positions. (4) Controls and displays 

 should be grouped in patterns that make for 

 the easiest operation and observation from 

 the point of view of the operator. (5) No 

 one part of the body should be overloaded 

 with work that could be assigned to other 

 body parts. (6) Any possible confusion of 

 controls or of displays by the operator should 

 be avoided by proper design or placement. 



It should be pointed out that these princi- 

 ples are merely convenient devices for sum- 

 marizing the best of what we know about 



Maximum tor 

 k'tt hand 



Normal for 

 left hand 



Normal for 

 right hand 



Maximum for 

 right hand 



Fig. 1. Normal and maximum working areas. 

 (From Barnes, 1) 



panel layout. How well they can be used in 

 panel design, of course, depends on how well 

 they are substantiated and implemented by 

 experimental data. Therefore, it will be im- 

 portant to consider the experimental work 

 on which they are based in some detail. Af- 

 ter that, the problems involved in applying 

 our research knowledge and general princi- 

 ples to practical design problems and the 

 methods of evaluating the suitability of 

 panels for human use can be discussed. 



Studies of the Human Factor 

 IN Panel Design 



The Practical Limits of the Work Space 



Although it is obvious that an operator 

 must be able to reach controls and perceive 

 displays before he can use them, several prac- 



tical problems arise in the design of equip- 

 ment to conform with this principle. What 

 are the practical limits of reach and vision of 

 the operators who are hkely to use the equip- 

 ment? How important is the position the 

 operator takes in front of the equipment in 

 determining what his effective working area 

 will be? How should a panel be oriented in 

 space for the greatest possible working space 

 and most efficient performance? Several 

 studies bear directly on these questions and 

 contribute the kind of specific information 

 that is needed to design panels properly. 

 Basically, they have all been guided by the 

 behef that the less the operator has to move 

 his body from resting position to use controls 

 and displays, the less fatigue he will suffer 

 and the more efficient will be his perform- 

 ance. 



The Limits of Reach 



Several approaches have been taken to the 

 problem of the limits of reach of an operator. 

 Early industrial investigators made empiri- 

 cal determinations of what they called the 

 "normal" and "maximal" working areas of 

 typical male operators sitting at horizontal 

 surfaces (1, 2). They simply had subjects 

 draw arcs on the surface with each hand, 

 once with the elbow as the point of pivot 

 ("normal" area) and once with the arm ex- 

 tended and the shoulder as the pivot ("maxi- 

 mal" area). This technique shows that the 

 working areas of an operator's hands are 

 semi-circular, and it clearly indicates the 

 areas in which the two hands can reach 

 equally well (Fig. 1). It is a conservative 

 estimate of the limits of reach, however, for 

 the limits it calls maximal are determined 

 without any trunk or body movement on the 

 operator's part. Clearly the reach could be 

 extended beyond these points by merely 

 moving the back away from the chair and 

 changing the shoulder pivot point. Never- 

 theless, the technique is a simple one that 

 could be used with appropriate modifications 

 for a provisional determination of the limits 

 of reach in any panel or for that matter in 

 three dimensions (Fig. 2). 



