Study on distance measurement for NAO humanoid robot

In many applications, there is the need to know the accurate distance between NAO and a certain object. Distance information is always of great importance for NAO to do extra tasks in many home monitoring and research circumstance. However, NAO is not equiped with a depth-sensing device which can offer the distance information directly. In this paper, we use four different methods to measure the distance. These ways and devices include the Asus Xtion Pro Live which is a low-priced 3D point cloud sensor, sonar which is a technique that uses sound propagation to position, its own cameras to achieve stereo vision, and NDI which is used to get the 3D coordinate and also the ground truth. We make a comparison among the four methods. The purpose of the study is to find the most appropriate way to measure the depth information.