1. A method for fusing data arising from a first image sensor and from a motion and/or position measuring module, the said first sensor and the said motion and/or position measuring module being integral and forming a device, the method being executed by a processing module in order to localize the said device, comprising: a first step consisting of acquiring several points on the images in order to define a current pose p t c of the device, including image camera and motion and/or position measuring module, for a given instant t, a prediction step of the predicted pose {circumflex over (p)} t k of the device (camera and motion/position sensor) for the same given instant t and using the measurements from the motion and/or position measuring module, a step where we determine an associated constraint ε k for the sensor k of the device (camera c and sensor k), a step where we automatically determine a weighting coefficient λ t of the said constraint, an estimation step of the current pose p t of the said device, a step of simultaneous optimization of the poses of the device (camera+sensor) by the bundle adjustment technique using the following cost function: E BA ⁡ ( X t , Z t ) = ∑ t ′ = t - ( N - 1 ) t ⁢ ɛ c 2 ⁡ ( [ p t ′ ⁢ s ] , z t ′ c ) + ∑ t ′ = t - ( N - 1 ) t ⁢ E p ⁡ ( [ p t ′ ⁢ s ] , Z t ) with 
 E p ( x t ,Z t )=ε c 2 ( x t ,z t c )+λ t 2 ε k 2 ( x t ,z t k ) ε c 2 : reprojection errors of the scene in the images x t : =[ps] the pose of the device and the scene z t c : =the observations of the scene detected in the image of the camera c at the instant t Z t =[z t c z t k ] combination of all the measurements for all the camera c sensors and of the sensors k of motion and/or position module at an instant t.