Tracking a varying number of people with a visually-controlled robotic head

Multi-person tracking with a robotic platform is one of the cornerstones of human-robot interaction. Challenges arise from occlusions, appearance changes and a time-varying number of people. Furthermore, the final system is constrained by the hardware platform: low computational capacity and limited field-of-view. In this paper, we propose a novel method to simultaneously track a time-varying number of persons in three-dimensions and perform visual servoing. The complementary nature of the tracking and visual servoing enables the system to: (i) track several persons while compensating for large ego-movements and (ii) visually control the robot to keep a selected person of interest within the field of view. We propose a variational Bayesian formulation allowing us to effectively solve the inference problem through the use of closed-form solutions. Importantly, this leads to a computationally efficient procedure that runs at 10 FPS. The experiments on the NAO-MPVS dataset confirm the importance of using visual servoing for tracking multiple persons.