ProductsSonar Image Stabilization A Powerful ToolMost ROV pilots are familiar with the vanishing target prob-lem when operating mechanically scanning sonar. During the approach with an ROV or any other moving platform, head-ing alterations of major proportion will often place sought-after targets outside of the viewing sector of the sonar on successive sweeps. What follows frequently, in order to relocate the ob-ject, is a sector increase on the sonar, as well as platform stabi-lization via contact with the bottom, which is time-consuming. Smaller unwanted changes in rotation of the sonar platform will either compress or expand the scanning density on the target, causing suf? cient distortion of the displayed image to deny ob-ject recognition. The Imagenex Model 881L-GS sonar, which employs a low drift gyroscope as well as a magnetic compass, is designed to be capable of correcting for orientation changes at a rate in excess of 500 degrees per second, which allows it to compensate for sudden turns and inadvertent bumping or jarring. Therefore, scan lines are displayed without blurring, compression, or smearing effects in all modes of operation, be it polar, sector or North-up. The North-up mode references the sonar image to true north when using an appropriate variation input. Regardless of platform heading changes, the sonar is able to keep the target continuously at the center of the scanning sector. Positional changes of aspect relative to the target are easily compensated by clicking the “Set Gyro Reference” button on the screen. www.imagenex.comLiDAR Ordered for Scanning Sonar for Wind Farm DevelopmentSearch and Survey Dutch energy company Eneco has pur-When an SUV went off a Minnesota bridge and into a river chased Fugro’s new wind LiDAR buoy in January the local sheriff’s of? ce was immediately noti-while a Japanese company is to deploy ? ed and the Winona County Dive Team dispatched. Two its buoy close to a ? oating power gener-bodies were quickly recovered from the vehicle, both wear-ation system. Fugro recently developed ing seatbelts, but two others were missing. The third victim what it calls an accurate and cost-effec-was found the next day, but the fourth could not be located. tive alternative to the traditional meth-Frigid water and limited visibility made a large scale search od of wind pro? le measurements for operation with divers nearly impossible. A decision was offshore wind farms. In January 2014 made to call in nearby Washington County Sheriff’s De-Fugro’s SEAWATCH wind LiDAR partment and its underwater robot. Two years earlier the de-buoy was deployed 75 km off the coast Photo: Fugropartment had acquired JW Fishers SeaOtter-2 ROV which of Ijmuiden in The Netherlands where has two cameras, four thrusters and a SCAN-650 scanning wind data will be compared with data from three levels on sonar. The SCAN-650 allows the operator to see much fur-a met mast at the site, together with data from a LiDAR ther than the video camera because the sonar’s sound wave mounted on the mast. Wind data collected conventionally, sweeps a 200 ft. diameter circle around the ROV. The wave using cup anemometers mounted on a wind mast is suscep-bounces off any object on the bottom and is sent topside tible to distortion from the sensors and the mast itself - typi-where it produces an image of the object on a laptop com-cally around 80m high. Fugro’s SEAWATCH wind LiDAR puter. Using their ROV equipped with scanning sonar the buoy accurately measures the speed and direction of wind Washington team was ? nally able to locate the fourth vic-across the diameter of wind turbine rotors in pro? le up to tim 125 ft. from where the vehicle entered the water and on heights of 300 meters.the opposite side of the bridge. www.jw? shers.comwww.oceanor.comMarch 2014MTR88 MTR #2 (82-96).indd 88 MTR #2 (82-96).indd 88 2/22/2014 2:20:06 PM2/22/2014 2:20:06 PM