Electrical and spring returning stalks for truck
applications: user evaluation and concept development of
steering wheel stalks

Abstract: This master’s thesis describes an evaluation of truck drivers’ attitudes
towards electrical and spring returning steering wheel stalks, and the
following development of design concepts for electrical and spring
returning steering wheel stalks in future Volvo Trucks. Electrical and
spring returning steering wheel stalks are today used in cars for the
interaction with steering wheel stalk functions such as direction
indicator, windscreen wiper and cruise control. An introduction of
electrical and spring returning stalks in Volvo Trucks would bring
advantages of adaptability and facilitate the stalk placement, but it would
also mean a loss of feedback and require a change in the truck driver’s
interaction with the steering wheel stalks.

An evaluation was performed with truck drivers driving cars equipped with
electrical and spring returning steering wheel stalks. The evaluation
focused on the direction indicator, windscreen wiper and auxiliary brake
and included driving a test route while performing user tasks and answering
a verbal questionnaire. The purpose of the evaluation was to explore the
truck drivers’ acceptance of using spring returning stalks, how the stalks
are experienced in ordinary driving situations and investigate possible
interaction difficulties and importance of different feedback.

The results of the evaluation indicate that the truck drivers are positive
of having spring returning in their truck. The auxiliary brake stalk should
be further evaluated since the cars were not equipped with spring returning
stalks for this function and could only be evaluated in a theoretical way.
Furthermore, the evaluation results show that the feeling of resistance in
the stalks is very important for an efficient stalk interaction and that
quick activation and cancellation of modes should be possible.

Based on the results from the evaluation, a requirement specification was
compiled and a number of sub problems were identified for the following
concept development. Concepts for spring returning stalks for the direction
indicator, windscreen wiper and auxiliary brake were generated, evaluated
and further developed. The final concepts for instance include directions
of moving the stalks, sequences of modes, control of rain sensor and
interval functionality, and light control functionality exclusive for the
North American market. The design of the stalks is of principles and is
visualized in rendered pictures of 3D surface models and a simulation was
developed to demonstrate the interaction with the stalks.