This thesis regards the development of a mobile assistant robot working at San Diego International Airport. The project is run by Innotech, a newborn start up based in San Diego, CA. An overview of similar case studies and the description of the whole project is provided in the first chapters, where the system architecture is analysed. The main features covered by the project are: SLAM, mechanical design, object detection and system interface. Afterwards, a deeper focus on the mechanical design is presented from three points of view: a comparison between different wheel configuration led to the choice of a differential drive; the power train design involved the selection of the motors, gearboxes and encoders; the CAD modelling in Solidworks of the whole structure has been carried on in order to 3D print the models and finally rapid prototyping the robot..