Camera-Inertial Sensor modelling and alignment for Visual Navigation

Inertial sensors attached to a camera can provide valuable data about camera pose and movement. In biological vision systems, inertial cues provided by the vestibular system, are fused with vision at an early processing stage. Vision systems in autonomous vehicles can also benefit by taking inertial cues into account. In order to use off-the-shelf inertial sensors attached to a camera, appropriate modelling and calibration techniques are required. Camera calibration has been extensively studied, and standard techniques established. Inertial navigation systems, relying on highend sensors, also have established techniques. This paper presents a technique for modelling and calibrating the camera integrated with low-cost inertial sensors, three gyros and three accelerometers for full 3D sensing. Using a pendulum with an encoded shaft, inertial sensor alignment, bias and scale factor can be estimated. Having both the camera and the inertial sensors observing the vertical direction at different poses, the rigid rotation between the two frames of reference can be estimated. Preliminary simulation and real data results are presented.