Nomination of controls of various layouts for heavy machinery

BACKGROUND: Control selection in heavy machinery may be a problem due to the poor compatibility of the commonly-used single line of vertical levers for controls. OBJECTIVE: This study examined the effects of control arrangements on directional compatibility and participant responses in terms of choice/function of controls. METHODS: We investigated experimentally, for a number of new designs of control arrangements, the selection of controls for requested functions of four different machines: fork lift trucks, excavators, tower cranes, and telescopic cranes. Control arrangements were designed with different levels of directional compatibility and participants were requested to nominate which control was related to each of the machine motions and to make ratings of certainty of response. A second part required participants to rank the various control arrangements in terms of their compatibility. RESULTS: The in-line control arrangement was worst for each machine and increased directional compatibility improved the stereotype strength, certainty of response and ranking of control arrangement. CONCLUSIONS: Directional compatibility is the main factor in the design of control/machine output arrangements due to its effect on stereotype strength and correct selection of control of a given function.