Abstract— Motion sensors as inertial measurement units (IMU) are widely used in robotics, for instance in the navigation and mapping tasks. Nowadays, many low cost micro electro mechanical systems (MEMS) based IMU are available off the shelf, while smartphones and similar devices are almost always equipped with low-cost embedded IMU sensors. Nevertheless, low cost IMUs are affected by systematic error given by imprecise scaling factors and axes misalignments that decrease accuracy in the position and attitudes estimation. In this paper, we propose a robust and easy to implement method to calibrate an IMU without any external equipment. The procedure is based on a multi-position scheme, providing scale and misalignments factors for both the accelerometers and gyroscopes triads, while estimating the sensor biases. Our method only requires the sensor to be moved by hand and placed in a set of different, static positions (attitudes). We describe a robust and quick calibration protocol that exploits an effective parameterless static filter to reliably detect the static intervals in the sensor measurements, where we assume local stability of the gravity’s magnitude and stable temperature. We first calibrate the accelerometers triad taking measurement samples in the static intervals. We then exploit these results to calibrate the gyroscopes, employing a robust numerical integration technique. The performances of the proposed calibration technique has been successfully evaluated via extensive simulations and real experiments with a commercial IMU provided with a calibra- tion certificate as reference data.

Chromatic aberration (also known as colour fringing) is a phenom- ena where different wavelengths of light refract through different parts of a lens system. Thus, the colour channels may not align as they reach the sensor/film. This is most notable in cheaper lenses, it is also noticeable at higher resolutions. We desire an image free of chromatic aberrations is simple, so all the planes are in focus. For a simple lens system this amounts to misaligned colour channels (red, green and blue). The misalignment is due to a uniform scaling and translation. There are many types of other chromatic aberrations. Complex lens assemblies introduce new distortions. We propose a method to deal with the simple, more common scenario. We later discuss possible ways to deal with more complex ones