Using special programming languages based, for example, on the theory of predicates, you can teach the robot to identify some signs of human emotions.

its similar to face recognition system. But not just this type. There are many different methods for it.

https://www.cmu.edu/news/stories/archives/2017/july/computer-reads-body-language.html

https://www.theguardian.com/science/2016/feb/10/horses-can-recognise-human-emotion-new-study-shows

http://www.telegraph.co.uk/news/science/science-news/12096738/Dogs-can-read-human-emotions-study-finds.html

Using special programming languages based, for example, on the theory of predicates, you can teach the robot to identify some signs of human emotions.

I have worked in a project (develop a machine learning system) to detect facial emotions by using deep learning and computer vision. The system developed can be used in robots (as a module). Do let me know if you need more information about the deep learning project and I shall share with you via cloud server.

I think it is based on the algorithm of combined multiple modes of emotion detection, such as face expression, audio, brain activity, skin conductance, heart rate, etc

http://www.independent.co.uk/news/will-ai-ever-understand-human-emotions-a7521076.html

http://www.newsweek.com/ai-artificial-intelligence-robots-emotions-humans-541595

https://www.weforum.org/agenda/2016/09/can-we-create-robots-with-human-emotions/

http://ieeexplore.ieee.org/document/7989198/

http://ieeexplore.ieee.org/document/7989198/?denied