Recoverable Autonomous Sonde Prototype For Subglacial Lakes Exploration:Heating And Control System Design

There exist a large number of liquid lakes thousands of meters under the Antarctic ice sheet.The discovery of the subglacial lakes has given scientists new hope in the field of polar scientific research.Many countries have been trying to measure and sample the water of Antarctic subglacial lakes in recent years.However,traditional drilling methods have a common problem,that is,they will pollute the lake water.This thesis combines the background and significance of the project,and draws on the experience and lessons in the process of developing the prototype of the subglacial lake probe,and then designs a new heating and control system for the engineering prototype of RECoverable Autonomous Sonde（RECAS）^[1].The system can achieve pollution-free drilling through the ice sheet by cooperating with the heating tips and winch system.After the probe arriving the specified depth,the scientific payload system can be used to complete lake water sampling,in situ measurement and other detection tasks.The heating and control system is mainly composed of three parts:power transmission and communication system,downhole measurement and control system,and ice surface system.Based on the development of the engineering prototype of RECAS,this paper proposes a heating control scheme based on 800V DC power transmission.I It not only simplifies the voltage reduction process and circuit design,but also makes the overall length of the drilling tool 7.2m and the weight of the drilling tool 350kg by combining the drawworks system and the measurement and control system,and the detector has a detection capacity of 500m under the condition of limited cable load.The downhole measurement and control system mainly complete the heating control based on high-voltage contactor,the automatic winch control based on tension feedback,and the data collection of multiple types of sensors.The system uses dual mainboards to work together and cooperate with other measurement modules to form an RS485 distributed measurement and control architecture.A fault diagnosis program and an IAP upgrade program are designed to facilitate subsequent system maintenance.This system has completed the unit test of each module in the laboratory,and carried out the high and low temperature test of the whole system.After that,the proposed system is connected with the heating system,winch system,and scientific load to complete joint experiments.Finally,a series of simulated ice drilling tests are carried out after the whole sonde is assembled.After module tests,joint experiments,and simulated ice drilling tests,the various functions and the stability of the proposed system have been verified.Test results also show that the proposed system can complete the specific measurement and control tasks and achieve the expected design requirements of the engineering prototype of RECAS.