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TopIntroduction
In this work, the main objective is the design of an underwater robot for cleaning pools. Basically, the use of available technology to make some housework or just to provide a friendly interface to control the home systems, configure Domotics (Home Automation), which represent a research area of Urban Automation. Some interesting works about Domotics can be seen in Leonik (2000), Alves and Mota (2003), Bolzani (2004), and Meyer (2004).
Even today, domestic cleaning robots are seen as exotic appliances or luxury toys. Cleaner pool robots do not have this kind of problem, establishing itself in the market over the years. The challenge to clean pools (mostly rectangular) is much smaller in comparison to the challenges associated with autonomous lawn mower robots, for example.
The basic mechanism of a cleaner pool robot consists of rotating brushes and two motors, one for the drive unit and rotating brushes, the other for suction, which not only allows filtering of water, but also the robot climb the walls of the pool to the surface.
In relation to navigation, it is customary to use rectangular or zigzag movements, with the aid of the walls (to crash into a wall, or detects a possible collision, the robot reverses direction of motion). There is a sensing to detect obstacles, and the robots have to external supply unit and the presence of a wiring surface.
The cost of this type of robot is high, with values ranging from U.S. $ 800.00 to U.S. $ 850.00. Figure 1 shows some examples of cleaner pool robots on the market today. The robots presented here have a cleaning average performance of 330 m2/h.
Figure 1. Some examples of cleaner pool robots: (a) TigerShark Pool Cleaner, by Aquavac (“Aquavac”, 2013); (b) Aquabot, by Aqua Products (“Aquabot”, 2013); and (c) Dolphin Diagnostic, by Maytronics (“Maytronics”, 2013)
In the next sections, we will present a review of the characteristics of pool cleaning machines, as well as the modeling of a robot, necessary to design of a prototype. The pool floor cleaning will demand brushes, and the pool wall cleaning will need a floater. We will also need a pump and a filter. The autonomy will require some sensors and some control devices. In addition, we will see some analyses of the robot structure. This paper is a revised and expanded version of the book chapter published by Lima Jr., Pina Filho and Pina (2012).
TopFloating System
Considering the cleaning of pool walls, we can think in two ways of doing this task: by using a sucker or a floating system. A sucker, or an array of them, depends of the wall material, and we do not want to restrain this. Then, the floating feature is the more reliable way to allow the cleaning of pool walls, because it depends only of specific mass of water instead of the pool characteristics.
The floating system (Figure 2) consists of an empty tube, which can be filled of water for submerge. A piston controls the input and the output of water: to get the water inside the system, a steel cable pulls the sealing disc, reducing the chamber pressure. Since the opening is in contact with the pool water, the chamber is filled. When the cable is released, a spring pulls the sealing, increasing the pressure, discharging the water to the environment.