Using a 3D time-of-flight range camera for visual tracking

We propose the usage of a novel 3D-Sensor for Visual Servoing in order to avoid the problem of depth estimation that ist to be solved in most servoing schemes. The sensor used in this paper is based on the time-of-flight principle and returns a depth image along with an intensity image. As these are acquired by the same CCD array, no calibration between them is necessary. As an application example a position-based eye-in hand servoing scheme is presented with the sensor mounted on the end-effector of a pan-tilt unit. An experimental tracking task was defined as follows: a sphere moving with respect to the pan-tilt unit has to be kept in the optical centre of the camera. We implemented velocity-based control of the manipulator joints and obtained the following results: the pan-tilt unit was operated at a contril frequency of 17.5 Hz and - starting from a skewed pan and tilt - the sphere could be regulated to the optical center in less than one second.