INSTRUMENTOS DE LA ALTERNANCIA

Summarizing the results of the literature review, the observations and interviews from the field studies, the following requirements are identified for the concept generation and development of the prototype. Furthermore, the related research questions are connected to them.

4.3.1 Functional requirements

A priority on a scale (low, middle, high) was given to each requirement individually based on the author’s evaluation. The abbreviations LR for literature review (see Chapter 4.1) and FS for field study (see Chapter 4.2) are used.

Table 4.1: Functional requirements.

Requirement F-01 Indicate future driving state of SAV

Description The driving states start driving, stop driving and wait- ing should be communicated towards the pedestrian.

Rationale If the SAV communicates the future driving state pedes- trians feel more comfortable in crossing the street in front of an SAV and are interacting with it.

Originator LR (Lagström and Malmsten Lundgren, 2015)

Fit criterion The pedestrians can determine which will be the next driving state of the SAV.

Priority HIGH

Requirement F-02 Active indication of SAV

Description The SAV actively indicates towards its surrounding that it is an SAV.

Rationale The user may be confused by the fact that the vehicle has no human driver and wheel behind the windshield.

Originator LR (Lagström and Malmsten Lundgren, 2015), FS (WEPods)

Fit criterion When the user can determine only from the vehicle approaching that it is an SAV.

Priority Low (Form factor / appearance of the SAV already helps)

Requirement F-03 Acknowledgement of multiple individual pedestrians

Description The SAV can acknowledge individual pedestrians.

Rationale If the SAV does not show the pedestrians that it sees them, pedestrians might get anxious in crossing the street.

Originator LR (Lagström and Malmsten Lundgren, 2015), FS (WEPods)

Fit criterion The pedestrians feel comfortable in the SAV noticed them individually.

Priority Low (Priority to first test with one pedestrian)

Requirement F-04 Eye-contact replacement (acknowledgement)

Description The SAV acknowledges pedestrians.

Rationale If the SAV does not show the pedestrians that it sees them, pedestrians get anxious in crossing the street.

Originator LR (Lagström and Malmsten Lundgren, 2015), FS (WEPods)

Fit criterion The pedestrians feel comfortable in the SAV noticed them.

Priority HIGH

Requirement F-05 Information on destination / next stop / direction

Description The SAV provides a visual information on the next destination / stop or direction the SAV is heading to.

Rationale This enables the pedestrians to see if they could use the specific SAV for their travel route / commute.

Originator FS (Stockholm)

Fit criterion The pedestrians can evaluate where the SAV is heading to and know if they could take the SAV for their next destination by just looking at the vehicle.

Priority LOW (not part of the pedestrian interactions at this stage)

Requirement F-06 Warning pedestrian for hazardous road situations

Description The SAV can warn pedestrians for hazardous road situations such as cars overtaking in a blind spot.

Rationale This enables to improve the safety on streets

Originator FS (Stockholm), Mercedes Benz expert interview

Fit criterion The pedestrians understand the signal by the SAV that it warns them and therefore, they are not stepping into the situation of being harmed or injured by any road user.

Priority MIDDLE (high complexity caused by variety of situa- tions)

4.3.2 Non-functional requirements

Usability requirements like learnability, efficiency, memorability, errors, satisfaction are non-functional requirements that also must be taken into account. Obtained non-functional requirements are described in the following:

Table 4.2: Non-functional requirements.

Requirement NF-01 The interface should communicate accurately, timely and continuous.

Description The interface should give the interacting people at each point of time the right information of, for instance, the current driving state. The communicated information should be observable at all times for the pedestrian (continuous and timely) and should be correct.

Rationale This enables a fluent and accurate communication to facilitate safety and comfort for the pedestrian.

Originator LR (Hoff and Bashir, 2015), FS (WEPods)

Fit criterion The pedestrian is informed about the driving state at the right time, continuously and the driving state is correct.

Priority HIGH

Requirement NF-02 The interface has to be simple and easy to understand

Description An easy and simple system allows to fastly receive the communicated message in a short amount of time.

Rationale An interface that is simple and easy to understand enables a good communication between SAV2P and includes a big number of users that can understand the system. Furthermore, it is vital for a fast commu- nication.

Originator LR (Hoff and Bashir, 2015)

Fit criterion All pedestrians can understand the message by the SAV in a fast way.

Priority MIDDLE-HIGH

Requirement NF-03 The interface should be visually appealing.

Description The interface should give the interacting people at each point of time the right information of, for instance, the current driving state. The communicated information should be observable at all times for the pedestrian (continuous and timely) and should be correct.

Rationale This enables a fluent and accurate communication to facilitate safety and comfort for the pedestrian.

Originator LR (Lagström and Malmsten Lundgren, 2015; Hoff and Bashir, 2015)

Fit criterion The pedestrian is informed about the driving state at the right time, continuously and the driving state is correct.

Priority LOW (not measured in the scope, future work)

Requirement NF-04 Make pedestrian feel calm

Description The pedestrian feels calm in crossing the street without thinking too much about how he/she should behave in a specific situation.

Rationale The interface should be easy understandable (NF-02) and therefore not overstrain the pedestrian’s mind. Furthermore it should communicate accurately, timely and continuous (NF-01) to facilitate a calm feeling.

Originator author & LR (Lagström and Malmsten Lundgren, 2015; Merat et al., December 2016)

Fit criterion The pedestrian behaves like on another zebra crossing and feels not negatively influenced.

Priority HIGH

Requirement NF-05 Make pedestrian feel comfortable in crossing the street in front of the SAV

Description The pedestrian feels comfortable in crossing the street like in another crossing situation.

Rationale The interface should be easy understandable (NF-02) and therefore not overstrain the pedestrian’s mind. Furthermore it should communicate accurately, timely and continuous (NF-01) to facilitate a comfortable crossing experience.

Originator author & LR (Visserset al., 2016; Meratet al., Decem- ber 2016)

Fit criterion The pedestrian behaves like on another zebra crossing and feels not negatively influenced in his/her comfort.

Phase II: concept generation

Phase II is based on the requirements and results given by the requirement analysis (Chapter 4). First, an overview of derived interaction scenarios is described, after that, a design work shop is outlined that served as an input for the interaction concept. Last, the generated interaction concept is illustrated. This answers also the research question a (Chapter 1.4): How can an SAV2P interaction concept look like?.