Chapter 16 Multiple Direction-of-Arrival Estimation for a Mobile Robotic Platform with Small Hardware Setup Caleb Rascon and Luis Pineda Abstract Knowledge of how many users are there in the environment, and where they are located is essential for natural and efficient Human-Robot Interaction (HRI). However, carrying out the estimation of multiple Directions-of-Arrival (multi-DOA) on a mobile robotic platform involves a greater challenge as the mobility of the service robot needs to be considered when proposing a solution. This needs to strike a balance with the performance of the DOA estimation, specifically the amount of users the system can detect, which is usually limited by the amount of microphones used. In this contribution, an appropriately carriable small and lightweight hardware system (based on a 3-microphone triangular system) is used, and a fast multi-DOA estimator is proposed that is able to estimate more users than the number of microphones employed. Keywords HRI  Lightweight  Microphone array  Mobile  Multiple direction of arrival  Reverberation  Service robot 16.1 Introduction The problem known as Multiple Direction-of-Arrival (multi-DOA) Estimation provides a unique challenge when being carried out in a mobile hardware platform, such as service robots. However, it plays an essential part of a natural Human- Robot Interaction (HRI), as it is important to know from where the users are talking to the robot and how many are there in the environment. C. Rascon (&)  L. Pineda Universidad Nacional Autónoma de México, Mexico City, México e-mail: caleb.rascon@iimas.unam.mx L. Pineda e-mail: lpineda@unam.mx H. K. Kim et al. (eds.), IAENG Transactions on Engineering Technologies, Lecture Notes in Electrical Engineering 247, DOI: 10.1007/978-94-007-6818-5_16, Ó Springer Science+Business Media Dordrecht 2014 209