Mattia De Agostino

Performances comparison of different MEMS-based IMUs

MEMS inertial sensors are widely used for navigation applications where size, weight, power and cost are key sides, such as autonomous vehicular control and pedestrian navigation. Otherwise, if there is no doubt that MEMS technologies represents an interesting turning point for low cost inertial-based sensors and applications, nevertheless it is absolutely true that, in order to obtain good positioning accuracies, it is necessary to investigate very well the behaviour of these MEMS sensors and realize special test calibrations, both in static and kinematic conditions. In order to evaluate the potentialities (and the limits) of these sensors, comparative tests have been realized considering MEMS inertial sensors with different characteristics and different performances, First of all, a static calibration of the sensors has been made, in order to compare the bias values and their stability with respect to the time. In particular, an Allan-variance analysis and a modified six position static test were carried out for each sensor, preserving carefully the same environment conditions for all the tests. After the lab tests, the performances of all the sensors were compared in a field kinematic test, integrating their data with a GPS solution.

Achievable Positioning Accuracies in a Network of GNSS Reference Stations

The Network Real Time Kinematic (NRTK) positioning is nowadays a very common practice not only in academia but also in the professional world. Since its appearance, over 10 years ago, a growing number of people use this type of positioning not only for topographic applications, but also for the control of vehicles fleets, precision agriculture, land monitoring, etc.. To support these users several networks of Continuous Operating Reference Stations (CORSs) were born. These networks offer real-time services for NRTK positioning, providing a centimetric positioning accuracy with an average distance of 25-35 kms between the reference stations.

A GNSS/INS-based architecture for rescue team monitoring

The present work shows the results that have been obtained using a low-cost pedestrian system made up of a GPS receiver and an inertial platform. This positioning system could be used by rescue teams to locate hazard zones and escape routes. Our study shows how multiple sensors can be used in a non-traditional way: the inertial platform is used as an odometer (step counter) in which the magnetometers allow the estimation of gyroscope drifts. The GPS receiver has instead been used to correct the bias when the GPS observations are sufficiently reliable. We have in particular focused on the estimation of sensor errors and on the reliability of the system, which is the main problem of this equipment.

GIMPhI: A novel vision-based navigation approach for low cost MMS

Over the last two years, the Geomatics research group at the Politecnico di Torino has developed a Low Cost System, in which only low cost sensors are involved. The system is equipped with webcams, an MEMS IMU and up to four GNSS receivers. During this development, several (non negligible) problems have been solved in order to obtain good quality after the data processing. One of the main problems of the low cost systems concerns the occurrence of GNSS outages. In this case, the IMU can only estimate the trajectory and the attitude of the vehicle for short periods. For this reason, considering the high number of frames available (about 3–5 frame per second, fps), a vision-based navigation (VBN) approach, called GIMPhI (GNSS IMU and PHotogrammetry Integration), has been adopted and tested. The navigation solutions have been refined by means of integration with a photogrammetric approach (bundle block adjustment) and a rigorous weight matrix has been adopted in order to consider the different accuracies of the various sensor observations (GNSS, IMU and images). A detailed description of this integrated approach is presented in this paper. The first tests and the achieved results are then shown in order to evaluate the reliability of the proposed approach.

A Review on Non Iterative Closed Form Configuration Matching and Rotations Estimation

Orthonormal matrices, Procrustes and quaternion analysis are closed form solutions of the configuration matching problem, common in geodesy as in the datum transformation problem. Literature reports more Procrustes based geodetic applications than Quaternions, which are more used in other application fields, such as aerospace navigation, robotics and computer vision. The large popularity of Procrustes in geodesy is mainly due to its capability to take into account a priori observation weighting in a simple way.