Keywords

1 Introduction

The mobility of today changes. Considering growing urbanization, increasing environmental pollution, and varying job-related challenges, mobility requirements are changing and novel mobility concepts are needed to counteract the resulting challenges in modern societies [1, 2]. Although current public transport systems comprise extensive bus networks as well as urban and intercity railways that extend to most major destinations, an efficient access for pedestrians to these means of transport is often limited [3]. Also, drivers who need cars for their job or carry out other accomplishments with the help of cars are often confronted – especially in urban spaces – with difficult parking situation and are urged to walk greater distances. In addition, the ratio of older persons in Western countries is growing steadily. In an aging society it is very important to develop devices which can support and assist the elderly in their daily life, since their mobility significantly degrades with age and differs from the mobility patterns of the younger members of the society [4, 5]. Understanding the dynamics of daily mobility patterns is therefore essential for the management and planning of urban facilities and services [6], as well as for the development of mobility innovations that meet the demands of today’s users of urban spaces.

In view of these facts, a comprehensive approach is needed that offers pedestrians of different age and physical fitness integrated “door-to-door” mobility services that enhance their connectivity, provide flexibility and assistance in everyday activities, and potentially increase the transit ridership [3]. At the same time, the mobility of tomorrow must be more climate and resource-efficient, more effective, and safer [7]. Due to the current mobility trends, it is foreseeable that in the near future a high proportion of electric vehicles will dominate the urban transport which opens up great possibilities for new (smart) technological developments. And, considering the congested (inner-)cities, especially the pedestrian mobility devices are likely to play a considerable role.

In the last years, an increasing number of mobility devices for pedestrians has become visible on the streets. A prominent example is the Segway, regarded as the first electrically powered, self-balancing transportation device for persons [8], which was introduced in 2001. Since then a rising competition on the market could be observed (e.g., electric scooters, hover boards). However, none of the technical innovations in this area was equally successful, or dominated the market: either, they addressed too narrow target groups, or they were simply poorly conceived. To develop flawless, functioning and well accepted pedestrian mobility devices for use in urban spaces, sophisticated ideas are needed to open up larger market shares to remain competitive. The technology must be absolutely effective, assistive, environmentally sound, safe for urban traffic, and fun for diverse user groups. To achieve this, however, in addition to technical ingenuity, a sophisticated research methods are necessary, which successfully involve all stakeholders in the design process: designers, researchers, but especially the potential end-users.

This article describes the application of such a participatory design [9, 10] to the development of a smart pedestrian mobility device (PMD), which is meant to support the pedestrians in their everyday activities (e.g., go shopping), ease the way to school, work or the bus stop, and just to have fun, cruising in the urban environment. To ensure a high user acceptance and widespread adoption of such devices, a user-centered approach was pursued that focused on the user’s particular interests and requirements. To achieve this, potential users were continuously integrated into all steps of the developmental and design processes (participatory design). “Typical” development and design processes of technical devices include the user at later stages, when the (merely) technical requirements are defined and a beta-version of the final product is produced. The users’ role is usually limited to some “fine-tuning” aspects, when designing the exterior or the HMI (human-machine-interface) of the device. However, an early integration of the user into the design process has been proven as useful and effective for developing “acceptable” technical devices, systems and interfaces (e.g., [11,12,13]).

In the following, we present the single research steps of the development process, from the concept stage to the development of the first prototype and the first usability evaluation of a smart PMD for the use in an urban context. The participatory research design plays an important role in the empirical approach and explores the users’ perceptions and needs in different aspects of use. The paper is structured as follows: Firstly, we present the conceptualization of the specific PMD that was to be developed (Sect. 2). In the next step, we describe the participatory design process for the user-centered (communication) design development of the device (Sect. 3) and outline research methods used in the participatory design approach (Sect. 4). Next, the main results are presented (Sect. 5) and discussed in Sect. 6. Finally, the limitations and future research duties are described in Sect. 7.

2 Specification of the Smart Pedestrian Mobility Device

The smart PMD, which served as the technical concept basis for the participatory design approach presented in this paper, is a multi-purpose mobility robot and assistant that unites many helpful functions in one compact, easy to use, and fun-to-drive electrically operated device. It has four multi-directional wheels – two each at the front and the back – for stable and easy riding and handling, making it usable for a large group of people (commuters, urban residents, tourists, elderly people, teens, etc.).

The innovative PMD has two main functions: One is the ride-on function for persons commuting through urban areas. The user rides on the device in a standing position and controls the ride through weight shifting (e.g., when the rider leans forward, the PMD moves forward and when the rider leans back, it moves back, or stops). A connection via an app on the smartphone shows all necessary data, like battery status, range, or the navigation area. Another designated function is the tethering function. The device is equipped with a semi-autonomous “follow-me” feature. Using the smartphone connection, the GPS position of the user is continuously detected and the mobility robot follows user’s every step while carrying heavy items (e.g., purchases from the grocery store).

For the communication with the user, different channels are designated: One is a LED-stripe on the device which gives the user visual feedback about various functions (e.g., turn left/right) and driving events (e.g., slowing down). A second communication channel is possible through built-in speakers, enabling an acoustic feedback. A further communication opportunity is the app, where all the important data regarding the state of the device, technical data, navigation maps, etc. can be displayed in more detail.

The PMD is conceptualized as a convenient device designed to bridge the last mile(s) to the peoples’ destinations, for fun rides and as an overall helpful assistant in the everyday life. In the following, the empirical approach to develop a first prototype of a PMD which is adapted to users’ requirements and needs, easy to use, and perceived as useful is described.

3 Participatory Design Process for a User-Centered (Communication) Design Development

In this article we examine communicative, functional, and operative requirements of users to the electrically operated, semi-autonomous PMD concept specified above. The aim was to identify criteria that can be used as a basis for a user-centered development process. These criteria should be addressed to deploy the full potentials of such mobile robots for the future (urban) mobility.

In this section, we describe aspects in the process of designing a pedestrian mobility device, which were considered in the scientific approach. Figure 1 depictures this process in detail.

Fig. 1.
figure 1

Single steps of the research process in the design of the PMD

Full size image

3.1 Determining User Requirements and Use Cases

Determining effective requirements for the PMD is pivotal to produce a device that meets the users’ real needs. To do so, in the present research a multi-methods approach was applied to gather relevant information about the requirements among users. However, the requirements device needs to meet can vary greatly, depending on user characteristics (e.g., age, mobility patterns).

Thus, defining relevant target groups is the first important step to get insights into the particular needs and demands of the targeted users. To create a mobility robot for the broadest possible use and/or assistance, persons of different age and gender, students, young professionals as well as professionally established persons took part in the research process. The composition and assignment of the participants to the respectively applied research methods are described in detail below (see Sect. 4).

In the early stage of the scientific process, the participants were encouraged to express their general opinions about the smart pedestrian device which had been introduced in basic terms. They were asked to reflect on possible benefits and to ask themselves, whether they would use such technology in the future. In addition, as it is sometimes easier to identify associated barriers associated with a particular device, the respondents explicitly focused on possible obstacles with the PMD, discussing possible facts which would lead them to reject the device. In group discussions (Fig. 2), participants suggested solutions for the identified barriers or formulated conditions under which the use would be possible for them.

Fig. 2.
figure 2

Discussion about perceived benefits and barriers of the use of a PMD

Full size image

All ideas and opinions regarding perceived benefits and barriers as well as the mentioned demands and conditions were collected and evaluated later in the scientific process.

3.2 Creating Communication Design

A PMD that is highly sensitive to the needs of its user, that is attentive to the permanently changing surroundings, and traffic safe, requires a sophisticated communication ability which provides the user with unambiguous and intuitive signals.

The process of the creation of such an explicit and clear language, which provides the user with precisely outlined, clear, and situationally presented hints (i.e., audible, visual, and/or haptic), is a very challenging task. There are some relevant points to be considered:

  • It is important to develop communication patterns that allow for a flawless user interaction.

  • The communication system should be perfectly adapted to the function/task, purpose or goal at which it is aimed.

  • The communication design should consider the already existing, deeply anchored signals which are intuitively understood in a certain way (e.g., red light for warning).

  • Different signaling modes must be correspondingly matched to one another and must be “dosed” accordingly for the user.

  • The visual and acoustic signals need to be redundantly coded but they should not be too complex or overload the user.

In the present study, participants “developed” the communicative signs for different functions and given events (e.g., on/off, braking, turn signals) linked to the daily use of the PMD from scratch. They created the signals in two modes: visual, using a spectrum of 265 colors on an LED-stripe, and acoustic, using a keyboard or their own voice which was recorded (as exemplary shown in Fig. 3).

Fig. 3.
figure 3

Top: tools for creation of visual and acoustic signals; bottom: examples of visual signal presets for different driving events for the pedestrian mobility device (Color figure online)

Full size image

The procedure followed three successive steps: In the first step, groups of participants generated events in which communication between the user and the device is necessary/desirable. In the second step, they made their own signal suggestions for specific functions and/or events, depending on their previous decision, whether an acoustic and/or visual signal was essential or not. In the third step, the group presented their signal proposals, giving the other participants of a focus group (see Sect. 4.1) a forum for discussion and evaluation of their results. All signals were then repeatedly evaluated during later stages of the research process.

3.3 Exploring Identity Design

According to the ever-increasing tendency of personalized technology (e.g., in the area of medical technology [14], mobile commerce [15, 16], or e-learning [17]), the next question which was relevant for the process of designing the smart PMD was the importance of identity characteristics and personalized character traits. The aim was to explore how potential users perceive and wish the device to be or to behave. The central question was if users wish the PMD to be equipped with a social identity, serving as an electronic “friend”, who knows its user’s personal needs, wishes and preferences to a given (day-)time or a specific situation. Participants also discussed about the importance of displaying basic emotions in the mobility device (e.g., joy/fun, distress, anger).

In a “do-it-yourself” workshop (Fig. 4) participants worked on the identity topic in three successive steps. In the first part, the brainstorming method was applied, where the persons tried to identify potentially relevant identity features. In the second step, they created paper prototypes of the device trying to highlight the characteristics that were especially important to them with regard to identity. In the third step, all paper prototypes were presented and discussed with the other participants.

Fig. 4.
figure 4

Various concepts for personalized prototypes of the pedestrian mobility device

Full size image

Finding of the personal identity preferences was important for the design process at least for two main reasons: Firstly, it affected the interaction with the user to a great extent, and secondly, it has played a decisive role in the development of the exterior design of the PMD.

3.4 Prototype Driving Experience and Usability Testing

Based on the information gained in the workshops, a first prototype of the pedestrian mobility device was assembled, which allowed for the actual interaction (i.e., driving experience) with users.

In a driving event, participants explored the driving features, trying to identify possible weaknesses. Initially, each person was exposed to a free driving and handling experience, for which there was no time limit. After gaining some driving routine, everyone had to run a route with obstacles as effectively and error-free as possible.

After the active driving experience, besides the evaluation of the mandatory usability criteria according to ISO 9241-11 [18], i.e., effectiveness, efficiency, satisfaction, participants had to assess their individual opinions regarding riding comfort, learnability, driving safety, and the perceived fun.

Finally, in short interviews participants expressed their opinions regarding driving properties and suggestions for improvements and optimization of the driving ability.

3.5 (Exterior) Design Evaluation

Eventually, the information gathered up to this point was evaluated and validated in a larger group of potential users.

In a quantitative survey, participants assessed different aspects relevant for the development of a highly-accepted pedestrian mobility device. They evaluated: (1) the exterior design, (2) the relevance of different criteria for buying the device, (3) the communication design (i.e., visual and acoustic signals for various driving events and functions), and (4) factors influencing the overall acceptance (e.g., perceived usefulness, learnability and perceived ease of use, fun).

With the results of the quantitative data gained in the five research steps, the first iteration in the participatory design process in developing the PMD was completed. We identified communicative, functional, and operative requirements of different users and generated opinions regarding potential fields of application (use cases), using the methods described below.

4 Research Methods Used in the Participatory Design Approach

In this section, the research methods used in the participatory design approach are described. We applied a mixed methods approach: qualitative (Sect. 4.1) and quantitative (Sect. 4.2) methods as well as hands-on experience. Such a “triangulation” (e.g., [19,20,21]) that means a combination of multiple research methods in the study of the same phenomenon, is very powerful for gaining insights and results, and for assisting in making inferences and in drawing conclusions [22]. Thereby, effectiveness of this triangulation is based on the premise that the weaknesses in each single method will be compensated by the counter-balancing strengths of another [23]. In this section, the particular methods used to gain relevant data and the associated samples of participants are described in more detail.

4.1 Qualitative Data Collection

To gain first insights into perceptions of an upcoming innovative technology, qualitative research methods represent an appropriate instrument. Qualitative methods focus on the content of relevant properties associated with the research question or study material [24] and are primarily used for exploratory purposes, allowing to gain an understanding of underlying reasons, opinions, and motivations. Their inductive feature allows that propositions may be developed not only from practice, or literature review, but also from ideas themselves [23].

In the process of designing the PMD, qualitative research methods were used both, individually and in groups. In the following, the methods used for the exploration of the respective main topics are briefly described.

Focus Groups.

Based on the interaction between participants in discussions about a specific topic, the method of focus group discussions aims at collecting qualitative data. Qualitative data is a source of rich descriptions and explanations of processes in the specific context. A systematic group interview allows to increase the depth of the inquiry and to unveil aspects of a phenomenon. In addition, group interactions may accentuate members’ similarities and differences, and give rich information about the range of perspectives, opinions, and experiences [25, 26].

In the present research, three focus groups were conducted to determine user requirements and demands in the following aspects of the use of a PMD:

  • In the first focus group (N = 6; age range: 27–66 years; 4 women and 2 men) participants initially reflected on the question, which requirements, benefits and barriers the utilization of a PMD can bring along. In addition, they discussed about conceivable use cases (as described in detail below) and considered under which conditions they would use such a technology innovation. In the further course of the focus group, participants conceived their own communication design for the specific functions and the specific events related to the drivability of the PMD.

  • The second focus group (N = 10; age range: 23–37 years; 4 women and 6 men) aimed at determining of the importance of the device’s identity and answered the question in how far the mobility robot needs to be personalized to its user. The main part of the meeting was the creative workshop (as described below) and the final discussion on this topic.

  • In the third focus group (N = 15; age range: 18–24 years) the main focus was the verification and validation of the communication design as well as evaluation of the exterior design. Presets of acoustic and visual signals for certain functions and events in the traffic were presented and discussed in the group. The most suitable signal, or variants with the most intuitive effects on participants, were included.

Use Cases.

The method of use cases is an important technique for the collection and specification of functional requirements [27]. They are specifically suited to understand the device from the user’s perspective and allow to find out in which situations the potential users are willing to use it.

In the present study, the method of the use cases was applied to define possible interactions between users and the device. As a part of the first focus group discussion, participants identified different use cases for the pedestrian robot: possible functions (e.g., ride function, “pack mule” function), different roles (e.g., personal assistant, dog sitter), and cases of application (e.g., as an entertainment/fun tool). The use cases gave impulses for later concepts of communication and exterior design.

Creativity Workshop.

The creative workshop played a very special role in the process of the development of the PMD. Considering that some people are less talkative, timid, and/or quickly distracted through the opinions of other discussion partners, creating space for their creativity and free thinking can truly bear special fruit.

In the present research participants of the workshop were free to either work alone or together with others in small groups. The task was to create a paper prototype of a pedestrian robot with all possible characteristics, functions, and elements desired for such a device. There was no time limit and the participants were provided with a variety of handicraft materials. In fact, some of the persons chose to work alone. Apparently, they took the opportunity to work undistracted and in this way expressed their own ideas, presenting the creations without the support of others.

User Interviews.

User interviews are a key activity for understanding different aspects, tasks, and motivations of the users for whom the device is designed. For the purposes of the presented study, short interviews were used as informal chats. As a part of the evaluation of the first prototype, participants were interviewed about the perceived pros and cons of the device. In addition, they were asked to make suggestions for improvement and they rated their physical and mental efforts when driving with the pedestrian robot.

4.2 Quantitative Research Methods

Quantitative research focuses on explanation of phenomena by collecting numerical data that is analyzed using mathematically based methods [28] and is a complemental addition to qualitative methods. An advantage of quantitative methods is that they provide precise, quantifiable, and reliable data that is usually generalizable to some larger population as long as the data is based on random samples of sufficient size. It allows researchers to test specific hypotheses that are constructed before the data is collected, and is useful for studying larger numbers of persons. The results are relatively independent from the researcher and can be evaluated by the quality criteria objectivity, reliability and validity (e.g., [23, 29, 30]).

In the present study, complementary to the above mentioned qualitative techniques, quantitative questionnaire as well as usability testing (hands-on experience) were applied to gain best possible knowledge for an optimal development of the pedestrian mobility device. In the following, the methods are described in more detail.

Questionnaire.

In addition to the qualitative techniques, a quantitative questionnaire consistently examined diverse factors that are essential for the acceptance and successful adoption of the pedestrian mobility device. Apart from demographic data and their habits to use different mobility devices, participants answered questions regarding requirements and demands with respect to the PMD. In addition to user factors, they were queried about their opinions regarding the ownership modality, i.e. whether they could imagine buying, sharing or renting it. Also, purchase criteria for the PMD and a general attitude towards technical innovations (e.g., “It’s fun to try out novel technical equipment.”) were part of the questionnaire. Moreover, the traditional aspects of technology acceptance, like perceived usefulness, satisfaction, and fun had to be rated. The questions had to be answered on 6-point Likert scales ranging from 0 (= strongly disagree) to 5 (= strongly agree).

Hands-On Experience.

The prototype of the pedestrian robot allowed first hands-on experiences with the device and brought significant insights regarding practical usage aspects. Following the first impressions after an introduction and driving instructions, participants had the opportunity to ride on the device. After a free driving and the first handling experience they had to complete a parkour ride. In a subsequent evaluation, the drivers were asked for usability ratings and shared their opinions, discussing the existing driving properties and their suggestions for improvement.

4.3 Participants in the Research Process

Empirical data was acquired from a wide range of potential users (N = 41). The recruitment aimed at reaching young, middle-aged, and older adults to account for different interests and opinions regarding the variable utilization opportunities of the PMD.

The age range of the participants was between 18 and 66 years (M = 29, SD = 11.7; 63% female) and comprised of people with various professional backgrounds (e.g., business economists, architects, psychologists, physicians) as well as students of different scientific fields (e.g., communication science, UI Design, computer science). Most participants were very open-minded with regard to technical innovations. The sample reached relatively high average values on the scale “technology fascination”, i.e., with regard to possession of technology devices (“I love to own new technical devices.”; M = 3.5, SD = 1.2 of 5 points), trying them out (“I like to watch new technical devices on the Internet or in shops.”; M = 3.7, SD = 1.5), fun with technology (“It’s fun to try out technical equipment.”; M = 3.9; SD = 1.2), and facilitation of some areas in everyday life (“Technical equipment makes everyday life easier for me.”; M = 3.9, SD = 0.7). These results indicate a quite tech-savvy sample.

In addition, most participants held a driving license (92%) and liked to drive a car (70%). Considering the required posture to ride on the PMD, participants also referred to their (more or less frequent) use of boards: 35% of the sample indicated to have used a skateboard and a longboard, 28% have done surfing, and almost every second person (48%) referred to have some experience in snowboarding. Thus, from the personal experience at least some of the participants could anticipate how the PMD is going to work when ready for the street.

Despite the fact that the PMD was still in the concept stage and not available as consumer product on the market, participants of the focus groups and workshops were asked about the conceivable and preferred usage modality: ownership, sharing, or renting. Interestingly, there was significantly less interest for buying the pedestrian device (27.5%) than for the idea to share (49%) or lend it (60%). Most of the sample (68%) perceived – at least in this time period – no need for a regular/daily use of the mobility robot. The idea to use it as a companion in leisure activities (33%) and/or as a domestic helper (45%) were rather more popular. About one third of the queried persons (31%) could imagine a use ‘just for fun’ of the PMD.

5 Results of the Participatory Design Approach

The results of the different stages of the participatory design process were elaborated from scratch according to the user-centered research and were analyzed, depending on the used methods as well as the nature of the collected data. Qualitative data were analyzed via content analysis. Quantitative outcomes were calculated by means of statistical methods.

Considering the early development phase of the PMD concept and the fact that most data originate from qualitative techniques, we confine the presented results to the main findings. These aspects are presented in a descriptive way by means of a central tendency of a variable and its dispersion [mean values (M) and the associated standard deviations (SD)]. Due to a relatively small sample size, the authors relinquish extensive inferential statistical analyses at this point. In the following, the main results are summarized by topic.

5.1 The User’s Requirements and Acceptance of a PMD

General Opinions About the Smart Mobility Robot.

Overall, the analysis of the empirical data showed a moderate positive attitude toward using the mobility device. As correlates to acceptance of the investigated device, participants responded to questions about their perceived usefulness (PU), perceived ease of use/learnability (PEU), practical use, supporting tool (to get things done faster), and fun. Figure 5 depicts the average values for the mentioned aspects.

Fig. 5.
figure 5

Aspects of acceptance of pedestrian mobility device concept: bar charts (left) and measures of central tendency [mean and standard deviation (SD); right].

Full size image

In general, the participants acknowledged the perceived usefulness and the practical use, but they appreciated the fun with the device more. Also, on average, respondents assessed learning to drive or navigate the device as easy. However, as can be seen from Fig. 5, the acceptance of the PMD concept was rather restrained due to the early stage of development: The mean values only just reached the middle of the scale (i.e., a neutral response).

Perceived Benefits.

Despite the rather low acceptance of the innovative mobile technology, the participants, who were encouraged to express their opinions about the device in the concept stage in the focus group discussion, perceived a lot of possible advantages of the PMD. Some of these ideas are listed below:

  • Convenient/natural posture: Driving the pedestrian robot demands a natural standing position and is controlled by natural (intuitive) movements.

  • High efficiency: Driving with the device is faster than walking.

  • Last mile device: Improvement of the “door-to-door” mobility and/or enhancement of connectivity between, for instance, work place and home.

  • Easy-to-use tool to link home, work, and other activity targets.

  • Potential enhancement of transit station access (e.g., for professional commuters, to get to the station more quickly).

  • Mobility tool in professional context to cover long distances (e.g., on university campus, industrial halls, medical center, etc.).

  • Service on demand (if someone needs help, e.g., with carrying of the groceries from the supermarket home).

  • Guide for strangers: To find one’s bearings in new/unknown places.

  • Replacement for the car in the city.

  • Reasonable costs of maintenance (electronically powered).

  • Environmentally conscious mobility alternative.

  • Fun tool: Simply good to stroll through the area.

In addition, there were many beneficial use cases the respondents could imagine with regard to the smart PMD:

  • Autonomous delivery service (e.g., for medication needed in case of illness);

  • Urban rental device (e.g., for the way home from the city);

  • Tourist guide/City tours guide;

  • Guide dog for the blind;

  • “The mule/donkey”/Assistant on long walking distances (e.g., on airports, trade fairs, big manufacturing facilities);

  • Assistance for motion-restricted persons;

  • “Dog sitter” (i.e., autonomously walking the dog).

In view of the number of the presented beneficial ideas, it is quite conceivable that potential users can adopt a positive attitude toward the use of the PMD. On the other hand, there are also some negative aspects that could dampen the merits; these are described in the next paragraph.

Perceived Barriers.

Besides the advantageous possibilities associated with the use of the mobility device, participants also considered possible disadvantages.

  • Loading area too small for purchases: In reality most people make one large purchase a week; thereby the device would fail due to loading space restrictions.

  • High accident risk, especially on crowded urban streets.

  • Unstable driving experience (e.g. high speed in bends).

  • Less physical activity in the daily life: For people who are less likely to take care of their physical fitness, this would mean even less exercise (“Why stand, if you can sit?”).

  • Uncomfortable, i.e., too big and too heavy to be carried (e.g., to continue the journey by train or bus).

Discussing the use cases in this context, brought a comment regarding a missing focus on specific target groups (e.g., it would be too dangerous for people who are restricted in their mobility). However, the respondents perceived substantially less barriers than benefits of the pedestrian mobility device, which is very promising result. In addition, some perceived downsides were directly linked to additional conditions which could enhance the use of the PMD – provided a compliance with the conditions. These are presented hereafter.

Conditions of Use.

Besides the clearly defined pros and cons of the use, in the group discussions participants revealed a conditional acceptance of the pedestrian mobility device. They identified the conditions listed below:

  • Special parking stations/safe storage areas for the device (to avoid having to carry it with you when shopping or using public transportation services);

  • Adequate battery service life (of a rechargeable battery);

  • Anti-theft protection in general and for the loading;

  • Protecting the loading from dropping down;

  • Attractive and functional design.

Generally, the respondents tended to positively assess the pedestrian mobility device. Conditions, like the ones presented above helped to structure their opinions, bringing to light some interesting topics, issues, and practicable solutions at the same time. Careful consideration of these conditions and the associated demands of potential users may lead to greater acceptance and adoption among potential future users.

5.2 Purchase Criteria

Although the participants had a high general technical affinity (as described in Sect. 4.3), most respondents were not particularly willing to buy the device, reaching on average only M = 1.6 (SD = 1.2) out of 5 possible points (5 = high agreement). In the early development of the mobility robot, they would rather rent or share the device with others. However, it was an important concern to find out what is important to potential buyers.

From the beginning of the study respondents were asked to rate the relevance of different buying criteria on a 6-point Likert scale ranging from 0 (= not important at all) to 5 (= very important). The descriptive results are summarized in Fig. 6.

Fig. 6.
figure 6

Ratings of the relevance for different purchase criteria for PMD

Full size image

The most important criteria for purchasing the PMD were price (M = 4.3, SD = 0.8) and its practical utility (M = 4.2, SD = 1.2), but fun (M = 3.8, SD = 1.2) and attractive design (M = 3.8, SD = 1.1) also played a considerable role. Prestige (M = 1.8, SD = 1.3) and the individual design possibilities (M = 2, SD = 1.3) were rather unimportant purchase criteria. Apart from these, the other mentioned criteria, like energy usage, safety and roadworthiness, as well as the environmental factors were rated as (quite) important, reaching mean values between M = 3.4 and M = 3.6 of 5 possible points.

Moreover, focus groups discussions revealed further highly relevant requirements: safety issues in the everyday road traffic, ergonomic factors (e.g., the weight of the device), the aspect of physical fitness since the device might replace walking as healthy lifestyle habit, as well as aspects of the interaction with the user (ease of the use). The latter requires a particularly careful and thorough processing. Hence, the following section elaborates in detail on the communication between the user and the PMD.

5.3 Expectations Regarding Communication Design

The development of the communication design of a smart pedestrian device that provides driving safety and is roadworthy (“ready for the streets”), is a complex process and calls for many iterative steps to get to an optimal final outcome. As described in more detail in Sect. 3.2, the process of PMD communication design development began with the (1) identification of relevant driving functions (e.g., turning right/left, to set the brake, reversing) and communication events (e.g., low battery charge level), over (2) group discussions on desired signal modalities and creation of signal presets, to (3) evaluations and ended with (4) determination of the particular visual and acoustic signals for specific functions and driving events. However, it should be stressed at this point that the authors do not claim finality or completeness of the presented results. Rather, the first general insights with regard to the preferred signal modalities, which were gained within the qualitative studies, are described in the following.

The main requirements for the visual signals were:

  • “Not too colorful”: Traditional color allocation according to deeply anchored schemata of known signals (red/yellow/green), eventually extended by some neutral colors (e.g., blue for the signal of stand-by status of the device).

  • Demand for intuitive color scheme for the typical driving events (e.g., red = “stop”, yellow = “steady”, green = “go”).

  • Unambiguous signaling for the user and for the environment: The use of existing traffic light system leads to intelligible understanding and interpretation of visual signals.

  • References for the visual signal characteristics:

    • Moderate pulse duration in order not to delay the traffic flow;

    • Customizable brightness, depending on light conditions outside;

    • Moderate and repeated rotation of the colors for a better perception of the signals in the footwell area.

The lessons learned for the design of audio signals were:

  • Non-intrusive but clearly perceptible acoustic signaling.

  • Clearly interpretable acoustic signals, especially as a warning signs (e.g., caution, an obstacle ahead!).

  • Precise matching of the acoustic and the visual signals.

  • Certain redundancy of the acoustic with visual signals, without stimulus overflow.

Concerning some general requirements with respect to the communication design, all discussion partners came to the congruent conclusion that, whenever possible, a reduction of signals should take place. Guided by the motto “Less is more”, participants argued that too many signals could distract the user too much from driving, and rather stress out than provide fun or assistance.

On the other hand, it should also be possible that the communication design adapts to the needs of the particular user. For instance, someone who suffers from color blindness would benefit considerably from enhanced acoustic signals for the pedestrian device, especially since the spatial arrangement, as is known from the traffic lights, is missing here. Then again, someone with hearing difficulties, would profit significantly more from the visual signal stimuli. Thus, flexible design would certainly increase the usability.

6 Discussion

Since the concept of smart pedestrian mobility devices presents a valuable solution for short distances as well as a cost and energy effective opportunity for locomotion in urban spaces, it is relevant to spread the idea and utilization in growing urban areas. To enhance the adoption of this new kind of mobility and to reach a high sustainability in the development of smart pedestrian mobility devices, an inclusion of users’ perceptions and demands, as well as a diligent implementation of insights derived from the participatory design process is highly recommended.

The aim of the presented study was to apply a participatory design approach and, thereby, identify criteria which can support the user-centered development process of such a mobility device, so that the best possible preconditions for the acceptance of the new technical device are created. Overall, the inclusion of future users in early stages of the technology development process was proven to be highly useful. Although still in the concept stage, participants were able to imagine using the PMD without being able to look at, or touch a prototype in the requirement and use case sessions. However, the resulting low willingness to buy the mobility robot indicated that the use cases and potential business models of the PMD are not sufficient, and need more refinement and elaboration. Different reasons are conceivable for explaining the low willingness to buy a PMD: First, in the early and explorative stage of the design process participants are forced to anticipate a technological concept, with which no familiarity is given and no real “hands-on” experience with a mature device is possible. Depending on the imagination, creativity, and innovativeness of the participant this might lead to a rejecting attitude and to an underestimation of acceptance. Another reason might be the nature or state of the device itself. Apparently, the technical device alone – at least in the early concept stage – is not enough to convince the (potential) user of its usefulness, and to evoke the desire to own a PMD. In this case, for successful mobility potentially more infrastructural background is required which is connected to the device. A potentially promising starting point is the integration of PMD in a multimodal public sharing system, which has a respective urban infrastructure available with renting stations combined with (e-)bikes and (e-)cars.

In line with ongoing research activities and recent innovations in autonomous driving, the PMD could also benefit from continued development of its autonomous functions, e.g., autonomous delivery of goods (e.g., bringing home your bags after shopping, delivering medicaments from the pharmacy) or as a city guide/physical navigation assistant. Here, it is important to consider that these different application contexts might activate qualitatively and quantitatively different acceptance-relevant benefits or barriers among users, which need to be captured by continuously involving the user in the design process. This refers for example to the safety aspect – for the mobility robot itself (protection against theft) as well as for its transport load (alarm signal when the goods are falling off or if goods are stolen from the PMD).

A further aspect which is related to the desire to ‘have one’, is the identity or personality of a PMD. Referring to “hedonic design approaches” [31], a device should elicit positive emotions and minimize negative emotions, in order to lead to a positive experience and high levels of customer loyalty. Hence, when designing a PMD it is important not only to give him “a life” (i.e., technical functionalities) but also “a soul” (i.e., communicative and emotional features), which make the PMD a valuable assistant and helper or even a friend. Designing a technical device which serves as a friend might provide a suitable solution for supporting “livable” life conditions for singles, elderly, and impaired people. Understanding the dynamics of the inhabitants’ daily mobility patterns is essential for the planning and management of urban facilities and services [32]. Creating a well-functioning, accepted, environmentally friendly, and economically reasonable mobility device that serves the user as an assistant or even as a friend could lead to a significant change of the cityscape and perhaps to a better emotional state of urban residents.

The purpose of this article was to present how the participatory design, using qualitative and quantitative research methods can be useful to explore and improve our understanding of the users’ needs with regard to technology innovation in the context of urban mobility. A key feature of multi-method research is its methodological pluralism or eclecticism, which, compared to mono-method research, frequently results in superior research [33].

In the described research project, there was enough time to carefully plan and conduct a suitable research approach. A successful use of different empirical methods, as it was described in detail above, led to multifaceted, informative, and for the various target groups specific results. However, we are aware of the fact that other (industry) projects are under higher time and cost pressure, which might limit the scope and/or variety of methods applicable in the design process. In case of time or cost restrictions, we recommend to involve the user at later stages in the design process, preferably in the second iteration level, i.e., to pre-develop design sets (e.g., visual and/or sound sets for communication design) as a starting point for the evaluation and fine-tuning by participants. Still, the researcher has to remain open if participants reject the designed pre-sets and has to allow the development of alternatives and own creative ideas.

7 Limitations and Future Research

Future research and developmental activities should ensure that the present needs of the users are accordingly considered without compromising the ability of future generations to meet their own requirements. This means a further integration of the potential users in the subsequent in-depth design processes.

Moreover, it is increasingly important for transport planners and public officials to decide how nonmotorized facilities should be managed. Decisions should be made about where and when specific modes and activities should be allowed, the rules everybody should follow, and how such rules should be promoted and enforced [34].

A further possible development of intelligent pedestrian mobility device could enhance the focus on the assistive function, like it is proposed for the i-Walker for elders [5]. This target population includes, but is not limited to, persons with low vision, visual field neglect, spasticity, tremors, and cognitive deficits. Technology which supports such users in their daily routine would strengthen their autonomy and (self-)confidence.

Finally, participatory research and design on PMD should be iteratively continued with technically advanced prototypes in more elaborated usage scenarios to capture more accurate and valid judgements, demands, and requirements by users.