Methods, systems, computer-readable media, and apparatuses for vehicular navigation are presented. Some configurations include computing a first attitude of a vehicle with respect to a reference frame at a first epoch; based on measurement data from an inertial navigation system (INS) of the vehicle, computing an attitude of the INS at a second epoch that is subsequent to the first epoch; based on the computed attitude of the INS and the computed first attitude of the vehicle, computing a second attitude of the vehicle at the second epoch; applying a constraint to the computed second attitude of the vehicle to produce an updated second attitude of the vehicle; and based on the updated second attitude of the vehicle, computing an updated attitude of the INS. Applications relating to road vehicular (e.g., automobile) use are described.

The present disclosure relates to a railway collision protection and safety system having a vehicle device located on rail vehicles at a work zone, a personal protection unit located with rail workers at the work zone, and a dispatcher processor at a control center. An authority limit within the work zone may be determined by the dispatcher processor, and an authority exceeded signal is sent to the rail vehicle when the rail vehicle is determined to exceed the authority limit.

A communication system includes communication units onboard a vehicle system. A first unit receives satellite positioning data and correction data based on phase measurements of satellite signals. A second unit receives the satellite positioning data. One or more processors determine a first geographical position of the first unit based on the position correction data and the satellite positioning data. The processors communicate the position correction data or a copy thereof to the second unit. The processors determine second geographical position data of the second unit based on the position correction data and the satellite positioning data. The one or more processors communicate the second geographical position data that is determined to the first communication unit.

A communication system includes communication units onboard a vehicle system. A first unit receives satellite positioning data and correction data based on phase measurements of satellite signals. A second unit receives the satellite positioning data. One or more processors determine a first geographical position of the first unit based on the position correction data and the satellite positioning data. The processors communicate the position correction data or a copy thereof to the second unit. The processors determine second geographical position data of the second unit based on the position correction data and the satellite positioning data. The one or more processors communicate the second geographical position data that is determined to the first communication unit.

A method is disclosed comprising: determining at least one relative altitude information based, at least in part, on at least one pressure information, wherein the at least one relative altitude information is indicative of a relative value of an altitude, determining at least one absolute altitude information associated with a data element of a database comprising map data, wherein the at least one absolute altitude information is indicative of an absolute value of an altitude, determining an estimation information based, at least in part, on the determined relative altitude information and, at least in part, on the determined absolute altitude information, wherein the estimation information represents an absolute value of an altitude. It is further disclosed an according apparatus, computer program and system.

A method is disclosed comprising: determining at least one relative altitude information based, at least in part, on at least one pressure information, wherein the at least one relative altitude information is indicative of a relative value of an altitude, determining at least one absolute altitude information associated with a data element of a database comprising map data, wherein the at least one absolute altitude information is indicative of an absolute value of an altitude, determining an estimation information based, at least in part, on the determined relative altitude information and, at least in part, on the determined absolute altitude information, wherein the estimation information represents an absolute value of an altitude. It is further disclosed an according apparatus, computer program and system.

A method for determining a 3-dimensional (3D) attitude of a platform includes receiving satellite relayed information regarding an ambiguous phase single-difference measurement (φ); resolving a phase ambiguity of the ambiguous phase single-difference measurement (φ) to determine an unambiguous phase single-difference estimate (ϕ); calculating coarse direction vectors x.sub.cor and y.sub.cor based on the unambiguous phase single-difference estimate (ϕ); estimating improved direction vectors x and y based on the coarse direction vectors x.sub.cor and y.sub.cor and by imposing constraints on the improved direction vectors x and y and an angle between the improved direction vectors x and y; and calculating the 3D attitude of the platform from the improved direction vectors x and y.

A method for determining a 3-dimensional (3D) attitude of a platform includes receiving satellite relayed information regarding an ambiguous phase single-difference measurement (φ); resolving a phase ambiguity of the ambiguous phase single-difference measurement (φ) to determine an unambiguous phase single-difference estimate (ϕ); calculating coarse direction vectors x.sub.cor and y.sub.cor based on the unambiguous phase single-difference estimate (ϕ); estimating improved direction vectors x and y based on the coarse direction vectors x.sub.cor and y.sub.cor and by imposing constraints on the improved direction vectors x and y and an angle between the improved direction vectors x and y; and calculating the 3D attitude of the platform from the improved direction vectors x and y.

An object of the present invention is to continuously estimate the position with high accuracy while the moving body is traveling. A position estimation device is installed in a moving body, and includes a position estimation unit configured to estimate a position of a subject moving body being the moving body in which the position estimation device is installed using any of positioning means of satellite positioning using a positioning satellite or radio wave positioning using wireless communication, and a positioning means selection unit configured to switch the positioning means the position estimation unit uses for estimation of the position of the subject moving body based on a traveling environment or a peripheral environment of the subject moving body.

A global positioning system (GPS) receiver and system for determining a geographical location associated with the GPS receiver using less than four GPS signals. The system can comprise a constraint module configured to receive one or more constraints that describe at least one characteristic of a GPS receiver when a number of GPS satellites within a line of sight to the GPS receiver is below a defined value. The system can further comprise a pseudo range calculation module configured to calculate a plurality of pseudo ranges between the GPS receiver and the number GPS satellites, wherein the plurality of pseudo ranges are to various orbital positions of the GPS satellites over a period of time; and a geographical location module configured to determine the geographical location of the GPS receiver using the plurality of pseudo ranges and known constraints of motion associated with the GPS receiver.