The study of musical instruments in playing conditions requires a highly controllable and repeatable excitatory mechanism. This mechanism has to be able to reproduce as closely as possible the human gesture in order to be representative of a playing technique. In the paper, we describe the development of a new string plucking device for the concert harp. This system, called DROPIC (Doigt RObotisé PInceur de Cordes), is a position-controlled two-degrees of freedom robot with a configurable silicone fingertip. In order to compare the plucking performed by DROPIC and by a harpist, trajectories are captured by a high-speed camera and the soundboard's vibrations are measured with an accelerometer. A set of features extracted from these data shows that the DROPIC plucking is comparable to the harpist one with a better repeatability. In addition to classical vibration and acoustic sensors, DROPIC can now be used to pluck a string and allows us to measure temporal features as well as spectro-temporal features in a repeatable and controllable playing context, thus creating an alternative to classical frequency-domain measurements of string instruments.