A Method for Half-duplex Relative Navigation Among Multiple Distributed Vehicles
Current relative navigation technology typically assumes that simultaneous two-way signal tracking (i.e. full-duplex communication) is operating between two vehicles engaged in a relative navigation estimate, and that data modulation is present on the signals to share pseudo range information. Researchers at the Johns Hopkins University, Applied Physics Laboratory have developed a new method which operates under half-duplex communication conditions, thereby leading to less complex radio frequency systems. In addition, it does not require the exchange of any data or the demodulation of data to produce a relative navigation estimate, and as a result, can be used in a non-interfering basis on communication systems that are exchanging data modulo operational considerations. The technique also uses a novel operational method that regenerates PRN codes and converges to a steady-state duty cycle, which can be dynamically adapted to meet relative navigation accuracy requirements. The invention is scaleable to large numbers of distributed vehicles and can operate in the presence of relative and absolute vehicle dynamics to provide relative velocity and acceleration estimates. The software implementation can use GPS tracking and navigation to resolve half PRN-chip ambiguity between code generators. Current techniques do not use regenerated PRN code modulation under free-wheeling conditions. In addition, the use of dynamically adaptive code generators allows multi-code channel operations to be possible.
This invention provides a means to continually maintain knowledge of relative position, velocity, and acceleration among vehicles. It can be used to maintain position for distributed sensing assets, help with locating lost, but cooperating objects, and serve as a means for collision avoidance and navigation control. This technology is considered applicable to any industry which requires an estimate of relative navigation (i.e. position, velocity, acceleration) among distributed assets, vehicles, or sensors. This includes science and military systems engaged in coordinated activities, industrial applications that maintain line-of-site communications among assets, and entertainment complexes that use autonomous or untethered objects such as rides or go-carts.
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