A GPS-aided inertial navigation method comprising: providing multiple sensors including multiple inertial measurement units (IMUs) and at least one global positioning system receiver and antenna, said IMUs and at least one GPS receiver and antenna being fixedly installed on a rigid body, said at least one GPS receiver providing position and velocity solutions; and providing a navigation computer with embedded navigation software or a computer, which is not navigation-dedicated, however has the required hardware interfaces and navigation software; characterized in that the computer is configured to perform the following activities: (a) interfacing with all IMUs and all GPS receivers; (b) running, in parallel, multiple standard inertial navigation schemes, one per each IMU; (c) computing the mean values of position, velocity and attitude solutions of all the IN schemes, thus obtaining a fused IN solution for the mean location of the IMUs; (d) computing the mean of all the GPS solutions, thus obtaining a fused GPS solution for the mean location of the GPS antennas; (e) applying lever-arm corrections, with the vector from the mean location of the IMUs to the mean location of the GPS antennas; (f) feeding the fused IN solution and the lever-arm corrected fused GPS solution to a single standard navigation filter so that said standard navigation filter does not have more filter states than a single GPS and single IMU navigation filter and accommodates the single fused IN solution and a single fused GPS solution, as if there were one IMU and one GPS receiver; (g) computing a least-squares solution for the rigid body's angular acceleration; and (h) running an IMU/IN/GPS correction module which, based on rigid-body physics and on the outputs of the single navigation filter, is configured to compute appropriate individual: (i) linear acceleration and angular rate corrections for each IMU, (ii) position, velocity and attitude corrections for each IN, and (iii) position, velocity, attitude, linear acceleration and angular rate-aiding messages for each GPS receiver. providing multiple sensors including multiple inertial measurement units (IMUs) and at least one global positioning system receiver and antenna, said IMUs and at least one GPS receiver and antenna being fixedly installed on a rigid body, said at least one GPS receiver providing position and velocity solutions; and providing a navigation computer with embedded navigation software or a computer, which is not navigation-dedicated, however has the required hardware interfaces and navigation software; (a) interfacing with all IMUs and all GPS receivers; (b) running, in parallel, multiple standard inertial navigation schemes, one per each IMU; (c) computing the mean values of position, velocity and attitude solutions of all the IN schemes, thus obtaining a fused IN solution for the mean location of the IMUs; (d) computing the mean of all the GPS solutions, thus obtaining a fused GPS solution for the mean location of the GPS antennas; (e) applying lever-arm corrections, with the vector from the mean location of the IMUs to the mean location of the GPS antennas; (f) feeding the fused IN solution and the lever-arm corrected fused GPS solution to a single standard navigation filter so that said standard navigation filter does not have more filter states than a single GPS and single IMU navigation filter and accommodates the single fused IN solution and a single fused GPS solution, as if there were one IMU and one GPS receiver; (g) computing a least-squares solution for the rigid body's angular acceleration; and (h) running an IMU/IN/GPS correction module which, based on rigid-body physics and on the outputs of the single navigation filter, is configured to compute appropriate individual: (i) linear acceleration and angular rate corrections for each IMU, (ii) position, velocity and attitude corrections for each IN, and (iii) position, velocity, attitude, linear acceleration and angular rate-aiding messages for each GPS receiver. (i) linear acceleration and angular rate corrections for each IMU, (ii) position, velocity and attitude corrections for each IN, and (iii) position, velocity, attitude, linear acceleration and angular rate-aiding messages for each GPS receiver.