Social Robot with End-to-End Methods to Select Responses and Gestures in the Context of Hospital Receptionist

Abstract

Many of us in the near future will be working together with robots. In the context of Human Robot Interaction (HRI), the dialogue system has a vital role in interacting with users. The reason behind this is because of robots' capability of effectively gathering required information but also providing easy access to a variety of services useful to people. Depending on the objectives, the dialogue systems can be classified into two categories; task-oriented and chat-oriented. Task-oriented dialogue system aids users to achieve a specific goal, and chat-oriented dialogue system is designed for entertainment by having a casual chat with users. A robot with a task-oriented dialogue system is highly effective in terms of reducing time and effort when replaced with a human operator. This thesis focuses on task-oriented dialogue systems for HRI. To the best of our knowledge, dialogue systems in HRI have been developed based on conventional pipeline approach. It consists of separately developed components; natural language understanding, dialogue state tracking, dialogue policy, and natural language generation. Moreover, the robot's behaviour relies on purely rule-based methods that developers manually define such a gesture and facial expression on the corresponding dialogue states. However, the conventional approach faces several challenges yet. The most prominent challenges include the approach being expensive, time-consuming, high training cost on the separated modules and error propagation from one module to another. To overcome this limitation, researchers have strived to develop the end-to-end dialogue system recently. It is based on an idea that Recurrent Neural Network (RNN) can be directly trained on text transcripts of dialogues to represent distributed dialogue representations. In this thesis, we address the limitations of the conventional approach in HRI and propose the end-to-end approach. We employed Hybrid Code Network (HCN), which is a practical RNN based dialogue system. We also proposed an RNN based gesture selector to select the best-fitted gesture according to the response generated by the dialogue system. Therefore, the proposed system is enabled to learn how to make a response from dialogue corpus, and it demonstrates a proper gesture without manually being defined by the developer. We perform the system evaluation in a real user evaluation setting and make comparisons to the conventional method. Empirical result shows that our proposed system has benefits in terms of dialogue efficiency, which indicate how efficient users were in performing the given tasks with the help of the robot. Moreover, we achieved the same performance regarding the robot's gesture with the proposed method compared to manually defining gestures.