I introduce quaternions by recounting the story of how Hamilton discovered them, but in far more detail than other authors give. This detail is necessary for the reader to understand why Hamilton wrote his quaternion equations in the way that he did. I describe the role of quaternions in rotation, show how to convert between them and matrices, and discuss their role in modern computer graphics. I describe a modern problem in detail whereby Hamilton’s original definition has been ‘hijacked’ in a way that has now produced much confusion. I end by describing how quaternions play a role in topology and quantum mechanics.

This chapter covers:

1. • The academic disciplines that come together in the field of human–robot interaction (HRI);

2. • The barriers created by the disciplines’ different paradigms and how to work around these;

3. • The history and evolution of HRI as a science;

4. • Landmark robots in HRI history.

This chapter covers:

1. • The role of nonverbal communication in interactions between people—how communication is enhanced by facial expressions, hand gestures, body posture, and sounds;

2. • The importance of interpreting, using, and responding to nonverbal cues in the appropriate way, both to successful human– robot interactions and to generate a positive perception of robots;

3. • Nonverbal communication channels that are unique to robots, as well as channels that replicate those commonly used by humans;

4. • How robotic sounds, lights, and colors or physical gestures with arms, legs, tails, ears, and other body parts can be effective for communicating with people.

This chapter covers:

1. • How a well-designed robot can lift interactions to the next level (physical design);

2. • How people do not treat robots as an assembly of plastic, electronics, and code but rather as humanlike entities (anthropomorphism);

3. • How HRI research draws on psychological theories, such as anthropomorphism, to design and study people’s interactions with robots;

4. • Design methods and prototyping tools used in human–robot interaction.

About this book; Christoph Bartneck; Tony Belpaeme; Friederike Eyssel; Takayuki Kanda; Merel Keijsers; Selma Šabanović; Notes on second edition

This chapter covers:

1. • The diverse areas of robot applications where human–robot interaction (HRI) is an important component;

2. • Applications beyond robots that are studied in a research context;

3. • Possible future applications;

4. • Potential problems that would need to be solved when HRI has a larger role in our society.

This chapter covers:

1. • The difference between affect, emotions, and mood;

2. • What roles emotions play in interacting with other humans and robots;

3. • Basic models of emotions;

4. • The challenges in emotion processing.

This chapter covers:

1. • The basic hardware and software components that a robot consists of;

2. • The techniques we can apply to make a robot ready for interacting with people.

This chapter covers:

1. • Current attitude of the general public toward robots and how this may change in the coming years;

2. • Possible shifts and developments in the nature of human–robot relationships, specifically companion bots;

3. • Further development of the technology of human–robot interactions, specifically artificial intelligence;

4. • The inherent issues with predicting the future (“crystal ball problems”).

This chapter covers:

1. • The complexities and challenges of human verbal interaction;

2. • The components of speech in human and human–robot interaction (HRI);

3. • The basic principles of speech recognition and its application to HRI;

4. • Dialogue management systems in HRI;

5. • Natural-language interaction in HRI, including the use of chatbots.

This chapter covers:

1. • The importance of the spatial placement of agents in social interaction;

2. • Basic human proxemics: how people manage space in relation to others;

3. • How a robot manages the space around it, including interactions such as approaching, initiating interaction, maintaining distance, and navigating around people;

4. • How the properties of spatial interaction can be used as cues for robots.

This chapter covers:

1. • Methodological considerations and various decisions you need to make in setting up and performing a human–robot interaction (HRI) study;

2. • The strengths and weaknesses of different research methods and how to identify them for understanding and evaluating HRI;

3. • How the choice of robot, environment, and context matter for study results;

4. • The importance of looking at new ways of reporting data and insights befitting HRI, even though there is a tradition of reporting experimental work.

This chapter covers:

1. • The influence of the media on human–robot interaction (HRI) research;

2. • Stereotypes of robots in the media;

3. • Positive and negative visions of HRI;

4. • Ethical considerations when designing an HRI study;

5. • Ethical issues of robots that fulfill a user’s emotional needs;

6. • The dilemmas associated with behavior toward robots (e.g., robots’ right to be treated in a moral way);

7. • The issue of job losses as a result of the increasing number of robots in the workforce.