ANATOMICAL AND ANTHROPOMETRICAL ASPECTS OF CONTROL DESIGN

Some of the principal anatomical and anthropometric aspects will be considered. For detailed specifications, some excellent handbooks are to be recommended (for example, Morgan et al., 1963; Grandjean, 1988). One important limitation of the recommendations available today is that they are based on the body measurements of Caucasians. For other ethnic groups, the measurements must be adapted for their proportionally shorter or longer leg lengths.

The following rules can be applied in the design of all types of control:

1. The maximum strength, speed, precision, or body movement required to operate a control must not exceed the ability of any possible operator.

2. The number of controls must be kept to a minimum.

3. Control movements which are natural for the operator are the best and the least tiring.

4. Control movements must be as short as possible, while still maintaining the requirement for ‘feel’.

5. The controls must have enough resistance to prevent their activation by mistake. For controls that are only used occasionally and for short peri­ods, the resistance should be about half the maximum strength of the operator. Controls that are used for longer periods must have a much lower resistance.

6. The control must be designed to cope with misuse. In panic or emergency situations, very great forces are often applied, and the control must be able to withstand these.

7. The control must give feedback so that the operator knows when it has been activated, even when this has been done by mistake.

8. The control must be designed so that the hand/foot does not slide off or lose its grip.

Table 5.1 gives a summary of the areas of use and the design recommendations for different controls. The controls are discussed in more detail later. Figure 5.1a, Figure 5.1b, and Figure 5.1c give the optimal areas for the different controls.

Stepwise Adjustments Continuous Adjustments

Rotary

Switch

Hand

Push-Button

Foot

Press-Button

Toggle

Switch

Small Wheel

Wheel

Crank

Pedal

Lever

Large forces can be developed

No

Yes

No

Yes

Yes

Time constraint for adjustment

Medium

Fast

Fast

Very fast

Recommended number of

3-24

2

2

2-3

positions

Space requirements for placing and using

Medium

Small

Large

Small

Small to medium

Large

Medium to large

Large

Medium to large

Activation by accident

Small

Medium

Large

Medium

Medium

Large

Medium

Medium

Large

Limits of control movements3

270°

3.2 x 38 mm

12.7×100

mm

120°

None

±60°

None

Small3

±45°

Legibility

Good

Acceptable

Bad

Acceptable

Badd

Acceptable

Acceptable

Bad

Good

Visual identification of control position

Acceptable

Badb

Bad

Acceptable

Acceptable0

Bad to acceptable

Bad

Bad

Good

Checking control position on

Good

Badb

Bad

Good

Good

Bad

Bad

Bad

Good

panel together

Usability as part of a combination

Good

Bad

Good

Good

Good

Bad

Bad

Good

of controls

TABLE 5.1

Recommendations for Controls

a The exception is “cycle ” pedals, which have no limit.

Подпись: Handbook of Control Room Design and Ergonomicsb The exception is when the control is back-lit and the light goes off when the control is activated. c Only usable when control cannot be turned more than one revolution. Round wheels/knobs must be marked. d Assuming that control can be rotated more than one turn.

Reference point is at the angle between seat and backrest

ANATOMICAL AND ANTHROPOMETRICAL ASPECTS OF CONTROL DESIGN

I_____ I_____ I_____ I_____ I_____ I_____ I_____ L

Подпись: 75 40 35 30 25 20 15 10 Подпись:0 10 20 30 40 50 60 70

Forward from Reference Point, cm

(a)

ANATOMICAL AND ANTHROPOMETRICAL ASPECTS OF CONTROL DESIGN

-20 -15 -10 -5 0 5 10 15 20

Distance to the Right and Left of Seat Reference Point, cm (b)

FIGURE 5.1 (a and b) Preferred vertical surface areas and limits for different classes of manual controls. (Modified from McCormick and Sanders, 1982. With permission.)