# Development of a Robotic Airboat for Online Water Quality Monitoring in Lakes
## 1 Introduction  
Water scarcity and quality are very issues discussed often in society, because they have been affected by the degradation caused by human beings--unrestrained pollution and its misuse in the world as a whole. Still, these issues are always in evidence because, although 71% of the Earth's surface is covered by water, only 2.5% is freshwater, as highlighted elsewhere [1]. The use of water by mankind depends on the acquisition, treatment, and distribution. In this context, it is important to search for alternative forms of water acquisition for consumption, such as rainwater [2]. However, the preservation of lagoons and tides has been potentially worrying as, besides compromising water quality, it also compromises underwater life--a source of livelihood for many people. The traditional process of monitoring water quality is basically composed of two steps--a manual collection of water samples at each time interval and laboratory analysis [3]. The National Water Agency of Brazil (NWA) operates a basic water quality network with 1340 points, nationwide, analyzing basic parameters such as pH, dissolved oxygen, and temperature. These parameters are obtained automatically by means of multiparametric probes, which are put in contact with water, avoiding collection, transport, and analysis of samples in laboratories. In addition, the monitoring of water quality in Brazil is carried out by a variety of state environmental and water resources agencies, sanitation companies, and companies in the electricity sector [4]. Additionally,according to the National Water Quality Assessment Program (NWQP) [4], however, there are no standardized procedures for collection, the frequency of collection, and analysis of information, which impairs the comparison of results and the sharing of experiences. Due to this lack of standardization regarding the number of collection points, this methodology can cause a significant variability, depending on the number of collection points, between the calculated and the actual results. In order to overcome this problem, it is important to carry out the planning of the collection points that can effectively represent the lagoon, as well as implement its correct execution. The variables, sample types, the frequency of sampling, and the location of collection stations should be carefully defined, according to the objectives [5]. The hypothesis to solve the problem of collecting water at several points is a standalone, autonomous, mini-boat equipped with test sensors, to carry out the analysis at determined points (waypoints), with more accuracy than a manual collection. The aforementioned mini-boat is an autonomous mobile robot. An agent capable of navigating the environment without human intervention, based on its sensors [6]. This type of robot is required when it is desired to explore static or dynamic environments in an autonomous way [7]. The analysis generated by the boat promotes to society a form of application that will help to evaluate and make decisions on the use and rational use of water reserves, raising awareness and contributing to the sustainable development of the communities, as well as obtaining data for research. In this work, it has been described as the development, construction, and implementation of a robotic airboat to measure water quality in lakes. [PERSON] et al. [8] states that path planning and control of such a robot in unknown environments is a major challenge. To resolve this issue, this airboat is equipped with an autonomous navigation model, using the Inertial Navigation System (INS) and Global Positioning System (GPS). In this model, the Inertial Movement Unit (IMU) provides the trajectory, while the GPS updates the data, since the IMU alone has a limited measurement frequency. INS and GPS data are processed, to determine the distance of the coordinates, their own position, and path, with their corrected error estimates. Depending on the wind influence, the boat must navigate differently, and the rudder is positioned to correct the route, in real time.