Towards online terrain aided navigation of underwater gliders

A terrain aided navigation algorithm has been developed through off-line trials which is suited for operations on an underwater glider. This method has been developed to enable persistent measurements using underwater gliders in regions where surface access is difficult or not possible. The algorithm is based on a jittered bootstrap particle filter. During two sets of off-line trials composed of a 10 km straight line segment and a 90 km survey segment the method was limited to RMS errors of 25 m and 50 m respectively. Integration of the algorithm into an underwater glider was achieved through the addition of a separate single board computer which is interfaced to the payload computer to retrieve the vehicle´s dead-reckoning solution, attitude, depth and attitude. Navigation updates and a status flag are sent back to the vehicle which logs the estimates in open-loop trials or incorporates them for closed loop trials.