8/13/2019 Ergonomics Part 1

1/2

ERGONOMICS

Ergonomics is applied to car body design with the aim of reducing the effort required by the

driver and passengers in different conditions particularly as regards driving the vehicle.

In the initial stages of car body design, the first task is to define positions of the occupants insidethe vehicle which is usually chosen in order to obtain a good compromise in terms of:

Optimizing postural comfort; Allowing easy access to commands (steering wheels, pedals, gear shifting levers); Reducing the effort to get in and out of the vehicle. Guaranteeing appropriate location of the powertrain and other mechanical sub systems

without compromising the space given to the occupants inside the vehicle too severely;

Respecting standard regulations concerning direct and indirect visibility.A specific aspect of automotive ergonomics is that the position of the occupants is substantially

fixed for long periods, while the driver must preserve the ability to act on view the nearby

environment for long periods of time. This implies that:

1. It should be possible to maintain the posture for long times without altering thecapability to act on the commands in the case of the driver; this happens only if the

angles between the main body segments are included in the ranges determined by the

anatomy of the articulations and the muscular system.

2. The driver should maintain the capability to rotate his head effortlessly. This requiresthat head is in the vertical position and not in contact with other supports such as the

head restraint.

The driver must be able to act on the pedals at all the times. This is possible if the legs are able

to move freely, implying that their role in bearing the load and keeping the posture is marginal.

The outcomes of this are the following:

3. The seat is the main physical support and bears the most of the weight of the occupant.The loads that act on the upper body are transferred by the backbone that,

correspondingly, has a particularly important role in all issues related to postural

comfort.

4. The legs act on the pedals with relatively small forces.5. The drivers arms act on the commands (steering wheels and gear shifting lever, for

instance). When compared to the past, the widespread use of servo systems that

characterizes modern cars has led to a considerable reduction of effort required to act on

the commands (steer, brake and gear shift lever). Nowadays discomfort is mainly

related to keeping the posture and not the need to operate the commands.

8/13/2019 Ergonomics Part 1

2/2

All these factors lead to the conclusion that the backbone is the most significantly loaded area of

the body, and therefore, plays a fundamental role in determining the level of discomfort. The

legs and arms, on the other hand, bear relatively weaker loads and they generate a discomfort

feeling only when the angles at the joints exceed the allowed range.

BASIC POSTURES FOR AUTOMOTIVE USE

SE: Seated RC: Reclined CR: Cramped