Evaluation of Pushbutton Arrangements in Automobiles

Abstract

The need for more fingertip operated pushbuttons on automobile dashboards, consoles and steering wheels has increased over recent years with the emergence of new, sophisticated entertainment systems, driver aids, and communication devices. The space to place these controls within a driver's reach envelope has remained fairly constant, or has actually shrunk due to the down sizing of cars and the addition of crash protection devices. For this reason designers are forced to design smaller pushbuttons and to place these pushbuttons closer together in order to fit them into the allotted space along with the accompanying displays. With designers reducing the pushbutton sizes and putting them closer and closer together, the driver is forced to devote more time, more and/or longer foveal eye fixations, and more concentration to push the correct pushbutton. This could impose safety problems if too much time and concentration are diverted from the driving task. An exploratory study was conducted in the field, during daytime under fairly realistic conditions to examine the push location distributions when required to push exactly at a certain coordinate point in a car as a function of coordinate point location, car speed, driving task and road surface condition. This study resulted in a database of 5400 coordinate points of push locations. A model was developed to allow a designer to determine the size and spacing of round, square and rectangular pushbuttons based on a desired probability level of pushing the correct button. This model also takes into consideration the desired probability level of pushing any adjacent incorrect buttons. A computer program was developed based on the model and the experimentally collected data. The designer is required to enter information about the pushbutton shape, size, in car location, speed, road surface condition, driving task and the population percentile value of the fingertip width. The model uses a fingertip width concept which requires the user to input the distance expressed as a percentage of the fingertip width by which the fingertip center lies outside the button border and will still result in the activation of the pushbutton. The software then outputs the probabilities of pushing the correct, any adjacent incorrect, and none of the buttons. Correctly designed pushbutton arrangements (adequate size and spacing) should minimize activation time, foveal eye fixations, fixation times and errors resulting in fewer repeated pushes, which in turn, should improve safety while driving and operating pushbuttons in the modern automobile.

Get full access to this article

View all access options for this article.

References

Kantowitz

B.H.

Sorkin

R.D.

, Human Factors: Understanding People-System Relationships, John Wiley and Sons, New York, 1983.

Deininger

R.L.

, Human Factors Engineering Studies of the Design and Use of Pushbutton Telephone Sets, The Bell Systems Technical Journal, Vol.39, pp. 996–1012, 1960.

Moore

T.G.

, Industrial Pushbuttons, Applied Ergonomics, Vol.6, pp. 33–38, 1975.

Human Engineering Laboratory Detachment, Human Engineering Design Data Digest, US Army Missile Command, Redstone Arsenal, Alabama, MIL-STD-1472, pp. 39, 1984.

Woodson

W.E.

Tillman

, Human Factors Design Handbook, Second Edition; McGraw-Hill, Inc., New York, pp. 464–465, 1992.

Diffrient

Tilley

A.R.

Harman

, Human Scale 4/5/6, MIT Press, pp. 29, 1981.

Bradley

J.V.

Wallis

R.A.

, Spacing of Pushbutton On-Off Controls, Journal of Engineering and Industrial Psychology, Vol. 2, pp. 8–19, 1959.

Adams

J.A.

, Human Factors Engineering, Macmillan Publishing Co., New York, pp. 284–285, 1989.

Sanders

M.S.

McCormick

E.J.

, Human Factors in Engineering Design, McGraw - Hill, New York, pp. 479–480, 1993.

10.

Zwahlen

H.T.

Adams

C.C.

DeBald

D.P.

, Safety Aspects of CRT Touch Panel Controls in Automobiles. Published in Gale

A.G.

Ed.: Vision in Vehicles II, North-Holland, Amsterdam, New York, Oxford, and Tokyo, pp. 335–344, 1987.

11.

Mourant

R.R.

Herman

, Direct Looks and Control Locations in Automobiles, Human Factors, Vol. 22, pp. 417–425, 1980.

12.

Zwahlen

H.T.

Kellmeyer

, Position Accuracy When Pushing Pushbuttons in a Car as a Function of Car Speed and Location - Implications for Design. Proceedings, VTI rapport, Sweeden, ISSN 0347-6030, 372A, Part 2, pp. 212–248, 1991.