An apparatus and method for measuring the vertical motion of a floating platform e.g. a survey vessel, caused by wave action. The apparatus includes a sensor having three accelerometers (11,12,13) arranged on mutually perpendicular axes (Ax,Ay,Az) so that one accelerometer acts in a vertical plane and the other two act in a horizontal plane. Output signals (S1,S2,S3) from the accelerometers are continually sampled through a multiplexer (14) and are passed through an ADC (19) and a shift register (21) to provide output signals for a data processor (D) which provides a signal A indicative of the vertical position of the platform. In the method, the accelerometer output signals (S1,S2,S3) are corrected for offsets by use of a reference signal (So) and the corrected signals are used to derive the signal (A) which may be double integrated to obtain the final signal (A3) relating to vertical displacement.
6201763 - Depthimeter - Owned by The United States of America as represented by the Secretary of the Navy (Washington, DC)
The depthimeter comprises a heave sensor, a mean path compensator and a combiner. The mean path compensator comprises a ranging device which measures the instantaneous distance of the vehicle from a fixed point on the vehicle to ocean surface as a function of time; a range compensator to compensate for signal dropouts in the ranging devices data, for sensor offset angle, and vehicle pitch and roll, thereby providing a signal that contains the vehicles vertical motion and the vertical motion of the sea surface. A low-pass filter within the mean path compensator eliminates the components of the resulting signal due to the motion of the sea surface and the high frequency components of the vehicle's vertical motion, thereby producing a signal that is the mean path of the vehicle, referenced to mean sea level. The combiner merges the mean path signal from the mean path compensator and a heave signal generated by the heave sensor to generate a signal that is a surface vehicle's draft relative to mean sea level or a submerged vehicle's depth relative to mean sea level. This signal is also the vehicle's vertical displacement with time relative to mean sea level.
A method of processing marine magnetic data is disclosed which comprises towing first and second magnetometers M.sub.1 and M.sub.2 behind a ship (10). Raw magnetic gradient data is obtained from the sensors and the trend of the gradient of the ship bias detected by the sensors determined. The method includes subtracting the trend from the raw magnetic gradient data to obtain corrected gradient data, and processing the corrected gradient data to provide a data output.
A control system to control the descent of a seafaring vessel, such as a lifeboat, into water is disclosed herein. The control system, and an accompanying method, control the descent speed of the seafaring vessel to minimise the possibility of setback after splashdown, and thus increase the probability of a safe and orderly launch.
The disclosed invention is an improvement on the traditional measuring wheel. When the odometry information is combined with two robust attitude sensors and an on-board computer, the instrument is able to perform useful measurements such as the calculation of an area or the description of a non-linear contour, as well as the traditional distance measurements and other uses.
The disclosed invention is an improvement on the traditional Measuring Wheel. When the odometry information is combined with two direction sensors and an on-board computer, the instrument is able to perform useful measurements to allow the calculation of an area or the description of a non-linear contour, as well as the traditional distance measurements.
