Xinhuanet "Xiangyanghong 09" ship on June 13th, after the "Zhenlong" manned submersible dive into the water, there is no sign on the road, and there is no GPS navigation, then how to determine the "Zhenlong" in the water position?
On the way to the first experimental application voyage to the South China Sea, the reporter interviewed Zhu Min, a researcher at the Institute of Acoustics of the Chinese Academy of Sciences and a member of the voyage field command. He told reporters that the underwater positioning of the "Zhenlong" mainly relies on two sets. Acoustic positioning systems: ultra-short baseline and long baseline positioning systems.
In the ultra-short baseline system, a set of positioning equipment is installed on the mother ship, and a beacon is installed on the "Jilong". When the submersible enters the water, the pair of accurately synchronized clocks on the mother ship and the "Zhenlong" simultaneously trigger the positioning device on the mother ship and the beacon on the "Jilong". There is a set of lifting and lowering acoustic array on the mother ship. There are 4 acoustic receiving transducers on the signal that can receive the beacon. By analyzing 4 signals, the distance, azimuth and inclination of the beacon and the mother ship can be calculated and calculated. The beacon is in the underwater position, that is, the position of the submersible under water.
Long baseline positioning requires no less than 3 beacons to be placed on the seabed. The long baseline transceiver on the "Zhenlong" periodically transmits an interrogation signal. Each beacon receives a signal after receipt, and the transceiver determines the correspondence according to the response time. The distance between the target and the "Dragon" is determined by geometric solution to determine the position of the submersible.
“Long baselines are more accurate than ultra-short baselines,†says Zhu Min. “The farther away, the greater the error in ultra-short baseline positioning. Usually the error is between two thousandths and one hundredth, if you dive 7,000 meters. The error may be up to 100 meters, and the long baseline accuracy can reach about 1 meter. The shortcoming of long baseline is the need to place beacons, which is time-consuming and labor-intensive, and the working area is fixed, while the ultra-short baseline is more flexible and the accuracy can meet the needs of most applications. Therefore, the positioning method will be determined according to the characteristics of the job task."
It is understood that during the sea trial from 1000 meters to 7000 meters, the "Zhenlong" was mainly positioned with an ultra-short baseline, and the long baseline was tested before the 7000-meter sea trial. In the upcoming first experimental application voyage, a long baseline positioning system will be used in order to make the positioning system of the "Zhenlong" more precise.
The first experimental application voyage of "Jianlong" started on June 10 and was divided into three segments. The first segment carried out the positioning system test in the South China Sea, and also carried out scientific research on the "Nanhai Deep Science Program", including Submarine ecosystems, organisms, and topography are surveyed; the second and third segments carry out near-bottom biological surveys, geological sampling, and underwater photography in the China Pacific Polymetallic Nodules Exploration Contract Area and the Pacific Northwest Cobalt-Crust Exploration Application Area, respectively. And the seafloor sediment dose response test, etc., is expected to take 113 days.
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