The Social Robot ‘Flobi’:Key Concepts of Industrial Design

Frank Hegel1, Friederike Eyssel2, and Britta Wrede1,2

Abstract — This paper introduces the industrial design of the social robot ‘Flobi’. In total, three key concepts influenced the industrial design: First, the robot head of Flobi appears as a cartoon-like character and has a ‘hole-free’ design without any visible conjunctions. Second, Flobi has dynamic features to display not only primary emotions, but also shame, a typical secondary emotion. Third, the structural design implements exchangeable modular parts. Through modular design, the underlying hardware is quickly accessible and the visual features of the robot (e.g., hairstyle, facial features) can be altered easily. A first study demonstrated the successful implementation of Flobi’s dynamic features, whereas a second study demonstrates that the exchangeable hair modules influence gender-schematic perceptions of the robot.

I. INTRODUCTION

The idea of robots as artificial beings is not a new one: The original meaning of the term ‘automaton’ implies autonomous beings having the ability to move on their own [1]. Vausanson’s flute and tabor player and Wolfgang von Kemepelen’s famous chess player, ‘The Turk’, designed in the mid 1700s, are early encounters between lifelike forms and mechanical machines. This machines invoked on people’s projections and expectations due to the lifelike behaviour displayed by their aesthetic form. Even today, social roboticists connect form and function in an attempt to develop lifelike social robots [2].

Thus, a general objective of social robotics research is to design robots that engage in social scenarios which are compelling and familiar to users. Given this objective, robots have to provide a social communicative functionality that is natural and intuitive to those who interact with the robot.

Social robots vary greatly in terms of appearance. To illustrate, some social robots appear strongly human-like, because the goal was to create an android surrogate of an existing person. On the other hand, many social robots ap-pear rather zoomorphic, caricatured, or technical [3].

In this paper, we present key aspects of industrial design that were implemented in the design of the newly developed,

cartoon-like robot. As depicted in Fig. 1, the social robot Flobi appears human-like because of its human-like facial features. Such human-like facial features were designed be-cause previous research has shown that a certain degree of human-likeness in appearance is necessary to produce ro-botic facial expressions that appear nearly human-like. In ad-dition, human-like appearance facilitates anthropomorphic inferences about the robot. Taken together, our design-related goals were twofold: First, we focused on the implementation of unambigously recognizable emotion displays. Second, we implemented a modular industrial design that makes quick changes in visual facial features possible.

After outlining previous research in Section II, we will outline the key concepts of industrial design in Section III. In Section IV we provide results of initial studies that were conducted to evaluate the robot. Finally, in Section V, we present a conclusion and recommendations for prospective research.

II. RELATED WORK

This section introduces previous research on ‘natural inter-action’, which is similar to a human-like interaction (Section 2.1). Furthermore, it will be illustrated that humans tend to anthropomorphize and they are particularly likely to do so when confronted with agents or objects that appear human-like (Section 2.2). Finally, this section provides evidence for the effects of attractiveness and babyfacedness on social judgments (Section 2.3).

1 Faculty of Technology, Applied Informatics, Bielefeld University, Universitaetsstr. 25, 33615 Bielefeld, Germany.

E-mail: fhegel@techfak.uni-bielefeld.de2 Center of Excellence in ‘Cognitive Interaction Technology’ (CITEC)

at the Bielefeld University, Germany

Figure 1. The social robot Flobi displaying sadness

2.1 Natural Interaction = Human-like InteractionInitially, the idea of creating social robots was inspired by biology. Social robots were used to study swarms or the behavior of insects [3]. However, current research in the field of social robotics focuses on human-robot interaction (HRI). The term ‘social’ in this case represents the fact that there are two or more entities within the same physical context [3]. Such a social robot should be able to communicate with humans, it should understand and even relate to humans in a personal way and finally, it should be able to understand humans and itself in social terms [5]. Thus, the main goal is to create an automaton that appears and behaves human-like during HRI [6]. However, to reach this goal, a social robot needs to be capable of conveying human-like signals and cues. Human-like signals,are ideally represented by human-like displays. The human face is probably the most variable and expressive part of the human body and as such, its signals and cues play a key role in natural interaction.

In general, the human face is composed of structural, dynamic and artificial features, all of which convey rich information about individuals. Specifically, the human face conveys information about age, sex, ethnicity, identity, fitness, and emotions [7]. Designers of social robots can use this repertoire of information to create robots whose faces appear similar to human faces [e.g., 8]. Human-like appearance is one factor that increases anthropomorphic inferences about nonhuman agents [9, 10].

2.2 AnthropomorphismAnthropomorphism entails attributing human-like proper-ties, characteristics or mental states to real or imagined non-human agents and objects [9]. According to the familiarity hypothesis [11], individuals draw anthropomorphic infer-ences, because it allows them to explain things we do not understand in terms that they do understand – and what we understand best is ourselves as human beings.

The Three-Factor-Theory of Anthropomorphism by Epley et al. [9] claims that the extent to which people anthro-pomorphize objects and animals is generally determined by three factors: First, Effectance Motivation describes the need to interact effectively with one´s environment. Attributing human characteristics and motivations to non-human agents increases the ability to make sense of an agent’s action and reduces uncertainty. Second, Sociality Motivation describes the need and desire to establish social connections with other humans. That is, when people feel lack of social connection they anthropomorphize objects more strongly. They do so to satisfy their need for affiliation. Finally, Elicited Agent Knowledge serves as a basis for induction primarily because such knowledge is acquired earlier and is more detailed than knowledge about non-human agents or objects. Therefore, the more similar to a human, the more do people use themselves as a source of induction when judging a non-human agent.

The key role of human-likeness in appearance has been demonstrated in a study by [10]. These authors conducted an fMRI study with three different robot targets which differed

in their degree of human-like appearance. Participants’ brain activity was measured during HRI with these robots. Results showed that the degree of human-likeness had a significant effect on participants’ cortical activity associated with Theory of Mind (ToM) and their judgments of the robots. Summing up, the more human-like an interaction partner appeared, the more did participants speculate implicitly about the robot’s intentions.

Furthermore, it has been shown that the quantity of facial features implemented in a robot influences perceptions of human-likeness [12]. But also, faces imply various qualities which probably have an effect on judgements. Specifically, due to the fact that a face continuously conveys information especially a poor designed face may cause negative attitudes towards an artificial agent or a social robot [13, 14].

2.3 Qualities of Facial AppearanceA vast body of research documents that people attribute more positive traits to attractive people than to unattractive ones. In psychology, this bias is known as the ‘attractiveness halo’ [16-19]. To illustrate, attractive humans are commonly judged as warmer, kinder, stronger, more sensitive, interesting, poised, modest, sociable, and outgoing [16]. It has been shown that even babys prefer playing with attractive than with unattractive puppets [20]. Importantly, [21] suggested that an attractiveness bias is also applicable to objects.

On the other hand, there is evidence that unattractive objects which appear rather human-like elicit unpleasantness. This is known as the ‘uncanny valley’ hypothesis [22]. This is particularly true for realistic robot faces with specific abnormal facial features (e.g., with regard to eye size). This suggests that the human visual system is particularly sensitive to cues indicating human-likeness [23].

However, not only does attractiveness or human-likeness of a face influence social perceptions. This is also true for babyfacedness. People with babyfaced facial features (e.g., a curved forehead, large and round eyes, a small nose and a small chin) are characterized as warmer, more naive and submissive and less dominant and competent than mature-faced individuals [7]. With regard to the industrial design of Flobi, we constructed a cartoon-like robot head with human-like facial features and baby-face cues to facilitate human-robot interactions.

III. KEY CONCEPTS AND REALISATION

This section describes the conceptual ideas which guided the robot s industrial design. First, Flobi has a cartoon-like appearance with similarity to humans to trigger a natural interaction. Second, by means of dynamic facial features, Flobi can express a variety of emotional states. Third, Flobi’s robot head consists of exchangeable modular parts (e.g., facial features such as hairstyle, lips, eyebrows). Because the modular approach makes it possible to alter Flobi’s appearance quickly and flexibly, this robot can be used as research platform to study HRI in a wide range of contexts.

3.1 Human Likeness and Structural Head DesignAccording to [12], the extent to which a face is perceived human-like depends on the quantity of facial features. To realize a high degree of human-likeness, Flobi’s facial features included eyes, eyelids, lips, ears, eyebrows, and a hair module. To have a warmer, a more submussive and a more naive perceived social robot and to avoid the aforementioned ‘uncanny valley’ effects, Flobi appears cartoon-like and babyfaced. Fig. 2 illustrates that Flobi has relatively large eyes, a small chin, small lips, a very small nose, and a round head shape similar to a baby’s head .

Moreover, the size of the facial features is meant to signify a match between form and function: That is, the user shall infer Flobi’s capabilities from its appearance: To give a visual indication of the robot s functional capabilities Flobi has very large eyes due to good visual capabilities, normal ears due to available hearing capabilities, and a small nose to indicate that Flobi does not have any olfactory capabilities. Furthermore, characters in computer games often have large

eyes to improve the readability of attention – the direction of large eyes compared to small eyes is probably better to recognise [24].

According to the Theory of Product Language [25] an object s visual features can be distinguished into two kind of signs: (a) ‘indicating signs’ explicitly explain an object’s function (i.e. how to use the object), whereas (b) visual ‘symbols’ are used to activate associations between an object and a specific context.

In other words, we differentiate visual features that represent Flobi’s inner states (e.g., the robot’s emotions) from visual features that are typically associated with specific knowledge-structures (e.g., long hair activating knowledge structures associated with females). Both types of visual features will be introduced in the following.

3.2 Dynamic Features: Displaying EmotionsOverall, the robot head has 18 degrees of freedom (see Fig. 3) to express emotional states, such as happiness, sadness, fear, surprise, and anger. Two actuators rotate the eyebrows, three actuators move both eyes, four actuators move the upper and lower eyelids, three actuators move the neck, and finally, six actuators were implemented to animate Flobi’s lips.

Furthermore, by means of four LEDs, red or white light can be projected onto Flobi’s cheek surfaces to indicate either shame or healthiness (see Fig. 4). Displaying shame is an interesting feature for further research, because it represents

a uniquely human emotion and has not yet been investigated in the context of social robotics.

Because industrial design requires covering technical conjunctions, we realized a ‘hole-free’ robot head. It was particularly challenging to meet this requirement with regard to Flobi’s lips. In few robots like the iCub [26] LED technology is used to project lips onto the face. Nevertheless, we decided against LED technology to display the robot’s lips because of the unnatural appeal of LEDs. Instead, Flobi’s upper and lower lips consist of neodymium magnets that can be actuated separately. Behind Flobi’s mask, coupled

magnets are actuated on sliding axes, with the motion range overlapping between upper and lower lips [more technical details in 27].

The large and overlapping motion range makes it possible to realize a relatively natural facial expression, because the corners of Flobi’s mouth are not fixed. Flobi differs from some prominent social robots in this regard (e.g., the Philips iCat [28]), because in these robots, the corners of the mouth are fixed. To realize a smiling face given the iCat, the corners of the mouth remain fixed while the the middle of the lip is moved downwards. This differs from the typical upward motion of the corners that usually characterizes human smiles. With regard to Flobi, its lip actuators can lift the corners of the mouth to form a realistic and natural smile without exposing holes or hardware. Fig. 5 illustrates the effect of this difference.

3.3 Structural Features: Modular Head ConceptSocial psychological research has shown that even minimal visual cues can lead to a target’s categorization, for instance, in terms of the person’s age, race, or gender. This categorization

Figure 2. Baby face schema drawing (1) and a profile drawing of Flobi (2)

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eye brows (2 actuators)

Figure 3. Overall 18 degrees of freedom and two LEDs

eye lids (4 actuators)

eye cameras (3 actuators: 1 horizontal, 2 vertical)

lips (6 actuators)

neck (3 actuators)

white and red LEDs

Figure 4. Blushing cheeks due to two red LEDs behind the surfaces

hand, the modular design has a clear practical advantage: With the neodymium magnets the neck, the face, and the back head can be removed within a few seconds, so that the underlying hardware is accessible.

IV. EVALUATION (INITIAL STUDIES)

Intitial studies were conducted to test the effectiveness of the key concepts of Flobi’s industrial design: The first study examined whether participants were able to infer the robot’s emotional states from the facial emotion displays and if they were able to do so correctly. The second study investigated the effect of hairstyle (long hair vs. short hair) as a gender cue on gender-schematic perceptions of the robot types.

4.1 Evaluation of Emotional Facial ExpressionsThe face with its 15 degrees of freedom makes it possible to implement displays of basic emotions [30]. That is, Flobi can display happiness, sadness, fear, surprise and anger. However, are users able to classify these distinct emotional states correctly? This was tested in an online survey [31] with 259 participants (160 female, 90 male) who evaluated the emotional displays of Flobi s predecessor Barthoc Jr. [32] and Flobi (see Fig. 7). The participants were ranging in age from 17 to 67 years, with a mean age of 27.7 years (SD = 9.97). Conceptually replicating [30], participants were presented with five images of each robot in a randomized order. The images depicted five basic emotions displayed by both robots. Subsequently, participants had to indicate which of the emotions would be portrayed by the robots. The results demonstrated that Flobi’s displays of basic emotions were explicitly more readable than the basic emotions displayed by Barthoc Jr. (see Fig. 8). Participants were able to classify displays of sadness (99,2%), happiness (83,3%), anger (81,2%) and surprise (54,5%) relatively correct. The

occurs quickly and automatically and activates knowledge structures such as stereotypes or social roles. A social role implies a set of behaviors that are expected of a person [29].

By means of the modular conceptualization of Flobi’s head, it is possible to alter the robot’s appearance without effort. This way, researchers can select specific features to manipulate users’ expectations and perceptions of the robot. Practically, all modules of the robot head can be combined as needed. This is possible because most of the head’s features are attached to the core using neodymium magnets. To build one specific character a set of ten parts in total is required. All parts – except for the elastic lips – are molded ABS plastic cases. Two main parts, a front head and a front neck, are screwed onto the technical core (see Fig. 6:1). The face and the back of the head are connected to the front head using neodymium magnets. Flobi’s back neck is connected to its front neck part using magnets as well. All these parts are available in human-like skin tones of varying shades (see Fig. 6:2). The hair modules (long and short hair) as well as the upper and lower lips are connected to the head using magnets, too (see Fig. 6:3-8). Flobi’s eyebrows can be plugged in with a pin that is plugged into an actuator behind the face mask. Hair modules, lips, and eyebrows are available in various colors (e.g., in black, brown, red, yellow, and blue).

The advantages of Flobi’s modular industrial design are two-fold: On the one hand, the modular robot head makes it possible to create different robot types instantly. On the other

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Figure 6. (1) visual core parts: eyelids, front head and front neck, (2) masks in different skin-tones of varying shades, (3) mask and brown female hair in front view, (4) masculine hair part, (5) various lips in different colors, (6) different eye brows in different shapes and colors, (7) yellow male hair part in side view, and (8) a collection of various parts. All Pictures: Copyright © by Barbara Proschak

Figure 5. Motion ranges of the Philips iCat (1) and of Flobi (2)

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display of fear (33,5%), however, was recognized less well, because obviously, many participants mistook surprise for fear (51,2%).

4.2 Evaluation of Gender SchemataA person’s hairstyle serves as a reliable, and the most

prominent gender cue. Previous research has shown that gender cues almost automatically activate gender-schematic knowledge [e.g., 33].

In a study with 60 participants (30 female, 30 male), ranging in age from 19 to 38 years (M = 24, SD = 3.86), we investigated whether this would also apply to robot targets. Specifically, we examined the effect of Flobi’s hairstyle on perceptions of the robot. That is, we used two different hair modules to create a long-haired ‘feminine robot’ and a short-haired ‘masculine robot’. Participants were asked to evaluate the ‘gendered’ robots with regard to gender-stereotypical traits and the robot’s suitability for typically female vs. male tasks. Both stereotypically female and stereotypically male traits and tasks were selected based on careful pretesting.

For instance, participants were asked using a 7-point Likert scale to rate the robot with regard to six stereotypically female traits (e.g., warmhearted, friendly, trusting, polite) and six stereotypically male traits (e.g., authoritative, aggressive, dominant, determined). Additionally, participants evaluated the robots’ suitability for pretested typically female tasks (e.g., taking care of children) and typically male tasks (e.g., repairing technical devices). As a manipulation check, we asked participants to judge the robots’ gender on a 7-point

Likert scale (from 1, indicating a high degree of femininity, to 7, indicating a high degree of masculinity). As predicted, the long-haired ‘female’ version (M = 1.65, SD = 0.92) of Flobi was perceived as more feminine than the short-haired one (M = 4.60, SD = 2.04), t(59) = 11.26, p <.001.

To test the main hypotheses, we conducted t-tests and found that the male robot was perceived as possessing more stereotypically masculine traits (M = 2.92 SD = 1.03) than the female robot (M = 2.68; SD = 0.92), t(59) = 2.36, p = .01, whereas the female robot was perceived as slightly warmer (M = 4.17; SD = 1.31) than the male robot (M = 3.96 SD = 1.32), t(59) = 1.93, p = .03.

Furthermore, typically female tasks were perceived as more suitable for the feminine robot relative to the masculine target – and vice versa. Participants perceived the female robot was perceived as more suitable for stereotypically ‘female tasks’ (M = 4.38; SD = 1.73) than the male robot (M = 3.92; SD = 1.54), whereas the male robot as more suitable for ‘male tasks’ (M = 4.54; SD = 1.21) than the female robot (M = 3.91; SD = 1.32), t(59) = 4.26, p < .001.

Taken together, these findings demonstrate that by means of the modular design, we were able to create distinct robot characters whose gendered appearance affected participants’ expectations about the robots’ personality and capabilities [further information regarding the experimental results in 34].

V. CONCLUSION

In this paper we presented the development of the social robot Flobi with respect to the key concepts of industrial design. The first key aspect is the realisation of a cute cartoon-like character with a ‘hole-free’ industrial design. All visible parts of the robot’s shape are connected by using neodymium magnets. Also, the robot’s movable lips are attached to the actuators using magnets.

Second, the robot has 18 degrees of freedom to dynamically display basic emotions. Additionally, white and red LEDs behind the robot’s facial mask were designed to indicate that the robot experiences shame. A first preliminary

1,2%

41,3%

happiness

sadness

anger

surprise

fear

56,1%54,5%

32,3%33,5%

81,2%

83,3%34,1%

99,2%

FlobiBarthoc Jr.

Figure 8. Readability of emotional displays of five basic emotions

Figure 7. Emotional displays of Barthoc Jr. (1) and Flobi (2), from left to right: happiness, sadness, anger, surprise, and fear

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2

Figure 9. Flobi with female (1) and male (2) hair

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2

study demonstrates that facial displays of happiness, anger, sadness, and surprise are readable. The fear display, however, appeared less recognizable. Currently, research efforts are undertaken to improve this aspect.

Finally, the third key aspect of industrial design is the implementation of modular parts to exchange the robot’s visual character. In an initial study we showed that people judge the robot differently depending on the hair modules that were applied. Specifically, the long-haired female robot was perceived to have more stereotypical female traits and to be better at stereotypical female tasks, whereas the short-haired male robot was perceived more dominant and better at stereotypically male tasks. Taken together, our findings demonstrate the effectiveness of the modular conceptualization of the social robot Flobi.

Obviously, a modular conceptualization of social robots represents a first step toward more systematic research on the effects of robotic appearance. We recommend taking this step when developing new social robots to study HRI.

ACKNOWLEDGEMENTS

This work has partly been funded by the German Research Foundation (DFG) within the SFB 673 ‘Alignment in Com-munication’ – Project C2 (Communicating Emotions).

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