Investigations into the Integration of Low-Cost GPS/INS Sensors

Abstract


 
 
 
 Global Positioning System (GPS) provides a method for directly obtaining instantaneous position and velocity estimates using satellites based passive range measurements. GPS is a whole day, all weather, passive, satellite-positioning system. Inertial Navigation System (INS) is a navigation aid system that uses a computer, Inertial Measurement Unite (IMU) that include motion sensors and rotation sensors to continuously calculate the position, orientation, and velocity relative to a known starting point. The integration of GPS/INS can help to overcome the limitations of the two systems providing integrated system better than either on a stand-alone basis. The integration of low-cost INS with dual frequency GPS has been widely studied and the same for the integration of tactical grid INS with low-cost GPS. However, during the last a few years, a number of low-cost GPS\low-cost INS integrated system have been introduced and become more and more common. For such integration level to be used in engineering applications, reliable investigations into the advantages and limitations are still needed and more efforts are required, which will be the focus of this paper.
 
 
 
 
 The methodology followed in this paper for evaluating the integration of low-cost GPS/INS sensors depends on evaluating the two sensors individually and comparing the results with those of the integrated system. The results show that low-cost single frequency GPS receivers are able to provide a comparable accuracy level in both static and kinematic carrier phase differential GPS(DGPS). As for low-cost Micro-Electro-Mechanical System (MEMS) based IMU, the accelerometers have provided instability comparing to gyros. The performance of gyros can be improved based on modelling the linear behaviour of the gyro drift. Tests show that such integration level degrades the precision of the gyro measurements and may not add any improvements to the quality of the individual GPS positioning.