Controls, Displays, and Interior Layouts 87
and frequently used controls in colder climates. The target size of frequently used and
safety-related controls should be designed to minimize the hand movement time by con-
sidering Fitts’ Law of hand motions (see Chapter 3). In addition, crash-protection standards
that limit the amount of protrusions of the control knobs in the head swing zone must be
considered in designing the shapes of the controls.
6. Operability: The direction of motion of a control should meet the population stereotypes
specied in SAE standard J1139 (SAE, 2009). The control must provide feedback (visual,
tactile, or auditory) to convey completion of the control activation movement. The control
effort (torque or force