In this paper, it is shown that computer vision, used as a redundant metrology mean, allows the control of a Gough-Stewart parallel robot without using any joint sensor. This result is highly relevant for the control of parallel mechanisms hard to instrument (for instance , hydraulically actuated ones) or with large displacements (for instance, large telescopes positioning systems). It is also very interesting since it turns computer vision, usually considered as an exteroceptive sensor, into a proprioceptive one, yet preserving its exteroceptive nature and non contact measurement.