Performance and Calibration of an Acoustic Doppler Current Profiler Towed below the Surface

Münchow, Andreas; Coughran, Charles S.; Hendershott, Myrl C.; Winant, Clinton D.

doi:10.1175/1520-0426(1995)012<0435:pacoaa>2.0.co;2

Cited by 37 publications

(20 citation statements)

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“…If, in addition, we have radians, and the term satisfies the condition that , , such that (28) then we can conclude that and, in consequence, that . The condition (28) is commonly referred to as persistent excitation [30], [35].…”

Section: ) Output Errormentioning

confidence: 92%

“…Previously reported studies show that the principal error sources arising in the Doppler navigation of underwater vehicles are heading and attitude-sensor accuracy and precision, and sensor-rotation calibration (alignment) errors between the Doppler sonar and the attitude sensor [7], [14], [21], [25], [28], [32], [44]. A new class of low-cost, true-north-seeking, three-axis optical gyrocompasses possess the ability to find true North at sea within about 5 min from a cold start, and provide a rated dynamic accuracy of 0.1 , about an order of magnitude better precision than the best available gyro-stabilized magnetic compasses, and are absolutely referenced to the geode.…”

Section: B Doppler-based Underwater Vehicle Navigationmentioning

confidence: 99%

“…In [14], Joyce reports an LS technique for estimating the heading alignment of a shipmounted Doppler, and this technique is employed in [32] to align a ship-mounted Doppler. Münchow and colleagues employ Joyce's technique to estimate the alignment of a Doppler mounted aboard a towed sled [28]. In [7], Brokloff reports a general LS technique for estimating the heading, pitch, and roll alignment errors in Doppler navigation.…”

Section: B Doppler-based Underwater Vehicle Navigationmentioning

confidence: 99%

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Adaptive Identification on the Group of Rigid-Body Rotations and its Application to Underwater Vehicle Navigation

Kinsey

Whitcomb

2007

IEEE Trans. Robot.

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This paper reports a novel stable adaptive identifier on the group of rigid-body rotations, and its application to a sensorcalibration problem arising in underwater vehicle navigation. The problem addressed is the identification of an unknown rigid-body rotation map from input-output data. General least-squares (LS) and adaptive identification techniques are commonly employed to identify general linear maps from input-output data, but do not guarantee that the resulting identified map is a rigid-body rotation. At present, an LS singular value decomposition approach is the standard method for identification constrained to the group of rigid-body rotations. This paper reports the first exact adaptive identifier on the group of rigid-body rotations, together with a proof of asymptotic stability. Techniques for navigating underwater vehicles are reviewed, and the Doppler-alignment calibration problem is posed. The reported adaptive identifier is employed to solve this problem, and performance of this adaptive identifier is evaluated on both laboratory and field experimental data. The results reported herein compare favorably with results obtained via previously reported LS techniques. The methodology reported herein may be of broader interest because of its applicability to more general problems in the identification, dynamics, and control on the group of rigid-body motions.

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Section: ) Output Errormentioning

confidence: 92%

Section: B Doppler-based Underwater Vehicle Navigationmentioning

confidence: 99%

Section: B Doppler-based Underwater Vehicle Navigationmentioning

confidence: 99%

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Adaptive Identification on the Group of Rigid-Body Rotations and its Application to Underwater Vehicle Navigation

Kinsey

Whitcomb

2007

IEEE Trans. Robot.

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“…Velocity fields were sampled with a downward looking 307 kHz ADCP of RD Instruments mounted in a vehicle towed besides the ship at 3-to 4-m depth (Münchow et al, 1995). Hydrographic profiles were measured by an Ocean Sensor OS200 and a Seabird SBE19 CTD.…”

Section: ™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™mentioning

confidence: 99%

“…Water Doppler velocity components were post-screened for percent good pings and vertical velocity. The calibration of the ADCP compass followed Joyce (1989) and Münchow et al (1995). Earth-velocity components were averaged for 25-point ensembles after calibration, resulting in a time step of 2 to 5 minutes between measurements.…”

Section: ™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™™mentioning

confidence: 99%

Observations of coastal upwelling off Uruguay downshelf of the Plata estuary, South America

Pimenta¹,

Garvine²,

Münchow³

2008

j mar res

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We analyze hydrographic and current observations of an upwelling center off eastern South America on the Uruguayan coast (ϳ35S) and downshelf from the Rio de la Plata estuary. Our observations show that the buoyancy-driven subtidal alongshore circulation is modulated by winds. During the winter, strong upwelling-favorable local winds forced the Rio de la Plata buoyant plume poleward. In the summer, the plume detached from the coast with warm and saline subtropical waters intruding from the north. These waters bounded the upwelling of cold waters in the nearshore area off Uruguay. A shallow submarine canyon cutting obliquely across the shelf facilitates the advection of cold waters into the coastal upwelling domain. An upwelling jet was detected off Uruguay for summer conditions, while for winter the plume configuration generated strong horizontal shear of along-shelf currents. Cross-shelf circulation was dependent on the coastal stratification. Under low stratification (summer) a two-layer circulation developed, with thick surface and bottom mixed layers flowing in opposite directions. High stratification levels (winter) modified this pattern by allowing circulation along a thick stratified interior.The existence of upwelling was linked to the history of wind events and shelf stratification. During the winter, downwelling winds frequently restore the plume, so the upwelling efficiency is very low. In the summer, downwelling events are less frequent and intense, so that the cumulative effect of upwelling events act to export the Plata freshwaters offshore. The reduction of inner-shelf stratification increases the likelihood of a full upwelling to the surface. Analysis of the wind-induced Ekman transport suggests that the Uruguay upwelling system reflects a seasonal wind pattern modulated by significant interannual variability.

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Rotation Identification in Geometric Algebra: Theory and Application to the Navigation of Underwater Robots in the Field

Stanway

Kinsey

2015

Journal of Field Robotics

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We report the derivation and experimental evaluation of a stable adaptive identifier to estimate rigid body rotations using rotors in Geometric Algebra (GA). This work is motivated by the need for in situ estimation of the alignment between sensors commonly used in underwater vehicle navigation. Here we derive an adaptive identifier using a geometric interpretation of the error to drive first-order rotor kinematics. We prove that it is Lyapunov stable, and we show that it is asymptotically stable in the presence of persistent excitation. We use the identifier to estimate the alignment between the Doppler velocity log sonar and the fiber optic gyrocompass used by underwater vehicles for dead reckoning (DR). We evaluate this method in the laboratory with a remotely operated vehicle (ROV), and then with an autonomous underwater vehicle (AUV) operating in the field at 1,200 m depth. Our results show that this technique reduces dead reckoning navigation errors on these platforms and provides comparable performance to previously reported SO(3) constrained Linear Algebra (LA) approaches. The rotor identifier has a number of advantages over these previously reported methods, including a more straightforward derivation, simpler gain tuning, increased computational efficiency, and reduced data manipulation.

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Performance and Calibration of an Acoustic Doppler Current Profiler Towed below the Surface

Cited by 37 publications

References 0 publications

Adaptive Identification on the Group of Rigid-Body Rotations and its Application to Underwater Vehicle Navigation

Adaptive Identification on the Group of Rigid-Body Rotations and its Application to Underwater Vehicle Navigation

Observations of coastal upwelling off Uruguay downshelf of the Plata estuary, South America

Rotation Identification in Geometric Algebra: Theory and Application to the Navigation of Underwater Robots in the Field

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