The Research About Microalgae Concentration Monitoring Technology Based On Unmanned Ship

Chlorophyll-a is the main pigment used by phytoplankton for photosynthesis and its concentration is used as an important indicator to describe the primary productivity of the ocean.An important reference data for evaluating the degree of organic pollution of seawater,marine water quality and detecting fishing grounds is the distribution of Chlorophyll-a concentrations.Unmanned vessels are highly flexible and small in size,and can carry a variety of special functional equipment to perform some special operations,playing a great role in both military and civilian fields.Based on this background,this study designs and implements an unmanned ship Chlorophyll-a concentration detection system,which realises the detection of Chlorophyll-a concentration in different waters and at different depths by an unmanned ship.At the same time,an online monitoring device for chlorophyll concentration and daily illumination of algae was designed.The diurnal distribution pattern and phototropism of algae in the depth direction of the water body were studied,and a theoretical model of underwater depth and Chlorophyll-a concentration was constructed by correlation analysis with the results of this study,and the data detected by the unmanned boat were simulated and compared using this model.Firstly,the overall solution of the unmanned boat was designed and realised,including structure design,drive design,control design and communication design.The capabilities of the unmanned vessel in terms of range,collection and detection,shore section control operations and data acquisition are ensured.Secondly,the luminescence mechanism of Chlorophyll-a fluorescence and the characteristics of the excitation spectrum and emission spectrum of fluorescence are introduced,focusing on the measurement principle of the fluorescence analysis method,which characterises the level of Chlorophyll-a concentration by the magnitude of fluorescence intensity,and reflects the concentration of algae in the water body by the Chlorophyll-a concentration.Based on this,a fluorescence detection device was designed,which uses a silicon photomultiplier tube as a photodetector and detects fluorescence well.Finally,the device was used to act in a simulated ideal environment for experimental measurements,and a theoretical model of Chlorophyll-a concentration was constructed and validated.An unmanned boat with a chlorophyll sensor was used for field detection,during which the unmanned boat operated and operated well,verifying the feasibility of monitoring algal concentrations based on the unmanned boat.The coefficients were calculated by substituting the theoretical model for the three sets of data obtained from the measurements on the surface,and then the inverse data were and analysed.The combined results show that under ideal experimental conditions,where light is detected,algal concentrations are significantly and positively correlated with light intensity;in the absence of light,algal concentrations at different depths vary slowly with the gravitational effect of the algae themselves.During the day,algal concentrations show a gradient in the vertical direction,decreasing from high to low;at night,the distribution changes,with algal concentrations at different depths remaining approximately the same.The model simulations showed similar trends to the measured values,with the measured Chlorophyll-a concentrations at 0.5 m depth falling below the predicted graphs and deviating significantly,and the predicted graphs converging at all nine sites.The thesis features a theoretical model of Chlorophyll-a concentration under ideal conditions.In practical application,the data collection of Chlorophyll-a concentration in different depths in the surface layer of the water body is carried out by sensors on board an unmanned boat,and at least three sets of depth and concentration data are substituted into the model for extrapolation,which can be used to predict Chlorophylla concentration in deeper layers of the water body,and the model is only applicable to ideal water body environment with no wind and waves and simple water quality.