— This paper proposes a method to control an I4R parallel robot by the observation of its legs with a calibrated camera. We show that the control law depends only on the edges of its forearms extracted from the image and that no proprioceptive sensors are used. Indeed, the variables needed for control (namely, the directions of the arms and forearms as well as the positions of the wrists ) can be reconstructed from the forearms edges. Experimental validation of the reconstruction is given and simulation of the control with realistic noises is performed showing the validity of the approach.