The following description includes the preferred best mode of one embodiment of the present invention. It will be clear from this description of the invention that the invention is not limited to these illustrated embodiments but that the invention also includes a variety of modifications and embodiments thereto. Therefore, the present description should be seen as illustrative and not limiting.
While the invention is susceptible to various modifications and alternative constructions, it should be understood, that there is no intention to limit the invention to the specific form disclosed, but, on the contrary, the invention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined in the claims.
As used herein, the singular forms “a”, “an” and “the” designate both the singular and the plural, unless expressly stated to designate the singular only.
The term “one embodiment” means that a particular feature, structure or characteristic with the product/system described in connection with the embodiment is included in at least one embodiment of the present invention.
The preferred embodiment of the present invention is directed towards an autonomous robotic system for swimming pool, comprises of a microcontroller (1), an ultra small self-contained microprocessor (2), a power distribution unit (3), a power source (4) with a battery management system (24), a plurality of electronic speed controllers (5), a set of thrusters (6) comprises of three thrusters (6a, 6b, 6c), an array of micro-pumps (7), a chemical store (8) comprises of a plurality of chemical chambers having swimming pool related chemicals and sanitizers, a sensor array (103) comprises of a total dissolved solid sensor (9), a pH sensor (10), a chlorine sensor (11), a temperature sensor (12), a leakage sensor (13), a water pressure sensor (14), an inertial measurement unit (15) and an ultrasonic sensor (16), a camera (17), a buoy (18), an underwater scrubber (34); a mesh (39) and a plurality of brushless DC motor (23), as shown in Figure 1. The sensor array (103), the chemical store (8) via the array of micro-pumps (7) and the thrusters (6) via the electronic speed controller (5) are connected to the microcontroller (1); the microcontroller (1) is connected to the buoy (18), the camera (17) and to the power distribution unit (3) through the microprocessor (2); the power distribution unit (3) backed up with the power source (4) provides power to the microprocessor (2) and the electronic speed controller (5); and the buoy (18) through an internet network (19) and an user interface (20) provides underwater communication to an user.
The main functionality of the proposed robotic system is to collect macro particles present on the surface of water, scrub the pool boundaries to remove algae deposition and dose chemicals while cleaning the pool. To fulfill these functions effectively, the robotic system navigates on the surface of the pool water in x-y plane, and needs to dive underwater and navigate on a similar plane parallel to the surface of the water. This path has been achieved by the robotic system with 3 degrees of freedom motions which are surge, heave and yaw. These motions are sufficient for the robotic system to navigate in the pool and perform cleaning and chemical dosing functions in an appropriate and optimum manner.
Another embodiment of the present invention is directed towards the thruster (6) used in the proposed robotic system. The robotic system features three thrusters (6a, 6b, 6c) for its motion in the swimming pool area. The thrusters (6a, 6b, 6c) navigate the robotic system in the horizontal plane in surge and yaw motion in the following manners:
- when the two thrusters (6a, 6b) have the forward polarities, the robotic system moves in forward direction, parallel to the axis of rotation of the thrusters (6a, 6b);
- when the two thrusters (6a, 6b) have the reverse polarities, the robotic system moves in reverse direction, parallel to the axis of rotation of the thrusters (6a, 6b); and
- when either of the thrusters (6a, 6b) have opposite polarities, then the robotic system rotates about an axis perpendicular to the plane of axis of the rotation of the thrusters (6a, 6b).
The two thrusters (6a, 6b) help in navigating the bot in the horizontal plane (surge - back and forth motion and yaw - rotation about vertical axis). When both the thrusters (6a, 6b) have the same polarity i.e, if both have forward or reverse polarity, then the robotic system either moves forward or in the reverse direction, parallel to the axis of rotation of the thrusters (6a, 6b). If either of the thrusters (6a, 6b) have opposite polarities, i.e, if one thruster (6a, 6b) has forward polarity and the other reverse or vice versa, then, the bot will rotate about an axis perpendicular (vertical) to the plane of axis of rotation of the thrusters. This enables the robotic system to make appropriate and calculated turns (left or right) while in motion in the pool. The thrusters (6a, 6b) chosen for the surge and yaw motion are Blue robotics make, T200 model. The maximum rated forward and reverse thrust of the T200 at 16V operation is 5.25kgf and 4.1kgf respectively and the maximum rated forward and reverse thrust at 20V operation is 6.7kgf and 5.05kgf respectively. The maximum power requirement at 16V and 20V operation is 390W and 645W.
Another embodiment of the present invention is directed towards the thruster (6c) located in the center of the robotic system, coincides with the centre of gravity and helps the robotic system to dive underwater and navigates inside the pool. The robotic system is equipped with the powerful thruster (6c) located in the center of the robotic system and coinciding with the centre of gravity. The thruster (6c) helps the robotic system to dive underwater and navigate inside the pool. The orientation of the thruster (6c) is such that it is located in concentric circles’ with the bottom scrubber (34). This rotation of the thruster (6c) creates a localized vacuum when it is powered in a forward polarity. The localized vacuum sucks the algae and other micro-macro particles, which are stored in the mesh (39). The mesh (39) is clamped to the body of the robotic system and covers the exit portion of the thruster (6c).
The operational voltage for the thrusters (6) is fixed at 16V. At this voltage the amount of thrust produced is sufficient to propel the robotic system at the desired speed so that an optimized cleaning of the pool and dosing of the chemicals takes place.
Another embodiment of the present invention is directed towards the cleaning of the pool which is categorized into 3 parts - Surface cleaning (physical cleaning) of macro particles, chemical dosing and scrubbing of walls and bed to remove algae.
Surface Cleaning: The surface cleaning mechanism of the robotic system comprises the steps of:
- the front-facing camera (17) detects a location of the suspended macro-particles on the surface of water and sends a signal identifies the relative position of the particles from the robotic system to the microcontroller (1) via the microprocessor (2);
- the microcontroller (1) commands the thrusters (6) to propel the robotic system towards the location of the particles; and
- the mesh (39) equipped with the robotic system collects and hold the suspended particles during the cleaning operation of the robotic system which is partially submerged in the water for aiding in the capturing of the particle into the mesh (39).
The robotic system features the front-facing camera (17) to detect the location of the suspended macro-particles on the surface of water. Its image processing identifies the relative position of the particles from the robotic system and sends the signal to the microcontroller (1). The microcontroller (1) commands the thrusters to propel the robotic system towards the location of the particles. The robotic system is equipped with the mesh (39) part to collect and hold the suspended particles during the operation of the robotic system. The position and orientation of the robotic system is such that it is partially submerged in the water, hence, aiding in the capturing of the particle into the mesh (39). The thrusters (6) propel the robotic system through the macro-particle. The mesh (39) part is a detachable component and is cleaned by an operator when completely filled. The size of the mesh (39) is No. 18 - with a sieve size of 1mm and the material of construction (MOC) is nylon polymer (polyamide).
Chemical dosing: Optimized chemical treatment of water is a critical function for the robotic system to perform. There are three types of chemicals on-board of the robotic system - chlorine, algaecides and stabilizers. All the three chemicals are in the liquid form and are easy to store and discharge. Each chemical is stored in a different chamber of the chemical store (8) and has an inlet opening and an outlet hose. The outlet hose is attached to the inlet of the micro-pump (7). The micro-pump (7) has a 2.4mm bore and is powered by a brushless DC motor (23) through a motor driven (22). Hence the flow rate for the chemical dosing is controlled. The amount of chemical to be dosed is assessed by taking into account the data from various sensors like the pH sensor (10), the Calcium/chlorine sensor (11), the temperature sensor (12), the total dissolved solids sensor (9). This data is fed into the Langelier Saturation Index (LSI) calculator and based on the instantaneous range of the Langelier Saturation Index, the micro-pump (7) is regulated. The speed of discharge of the micro-pump (7) is controlled by the microcontroller (1).
Wall and bed scrubbing: The salts produced by humans and other organisms tend to deposit on the surface of the wall and bed of the pool. Additionally, if the pool water has a high value of hardness, then the water is completely saturated and deposits the calcium ions on the surface of the walls. Additionally, along with salts, algae develop in certain hotspot regions of the pool. The algae adhere to the surface of the wall and bed, and are usually slimy and slippery in nature. Algae colonies can be easily scrubbed off the surface using mechanical force. The robotic system features the camera (17) that is facing the bed of the pool. The camera (17) captures images in a continuous frame and sends it to the microprocessor (1) for detection of algae hotspots by image processing.
Another embodiment of the present invention is directed towards the underwater scrubber (34). The body of the scrubber (34) is made of plastic and houses a series of nylon bristle strands (35) grouped together in 15-17 numbers. The length of the bristles (35) from the surface of the scrubber (34) is 25mm. The bristle groups (35) are positioned such that they are uniformly distributed over the surface of the scrubber (34) in concentric circles. The scrubber component (34) has a through-hole at its centre that is designed such that it is concentric with the central thruster (6c). This helps in sucking the scrubbed algae and salts from the walls and bed that gets collected in the mesh (39). The scrubber (34) houses an internal gear that meshes with the pinion which is coupled to the shaft (22) of the brushless DC motor (23). The motor (23) is housed inside the robotic system and the shaft (22) is protruding towards the exterior. The speed of the brushless DC motor (23) is usually high and can be controlled using the electronic speed controller (5). The gear ratio of the pinion-gear combination is designed such that, the torque produced by the gear suffices the need of scrubbing the wall.

Additional part components of the robotic system are namely a robust water-proofing hull to improvise the strength requirements such as ultimate yield strength, impact strength, slots are added in the robotic system profile to assimilate electronic parts pressel vessels like the camera (17), various types of sensors namely pH (10), Temperature (12), pressure (14), TDS (9), LSI and water alkalinity testing sensors (11). Profiles are made to improve the functional characteristics of the robotic system. Heat flow is assured using heat transfer fins to allow direct flow of heat between the passages. The major aim of the parts components is to maximize the efficiency and increase degrees of freedom.
The figure 9 shows the front view of the schematic model of the proposed robotic system in which the upper outer body (101) and the bottom outer body (102) are displayed. Further, the figure 9 shows the placements of the thrusters (6a, 6b) with thruster bracket (6’), the exterior connectors (41), the scrubber (34) on the scrubber mount (12) with nylon bristle stand (35), the ultrasound sensor full threaded type (28) and the ultrasound sensor extended horn type (28), sensor array (103), the M5 bolts (42), the mesh (39), the camera (17), the collection bin (40) and of the chemical chamber cap of the chamber store (8).
Furthermore, the figure 10 shows the placement of the brushless DC motor (23) with the motor driven shaft (22) in the side view of the schematic model of the proposed robotic system and the figure 11 shows the placement of the bearing balls (45), bearings inner race (44), bearings outer race (43) and the thruster (6c) in bottom view of the schematic model of the proposed robotic system.
The chassis is the skeleton of the body of the proposed robotic body, protecting and helping in absorbing shock loads. The material of construction of the chassis is Al 6061 T6 grade. The structural components are welded together using TiG welding method which helps in rigidity of the component. Commercial aluminium alloys utilize zinc as the major alloying element and when combined with a small amount of magnesium the result is a heat-treatable alloy which offers very high strength. The Al 6061 series alloys have one of the highest strength to weight ratio making it ideal for usage in the vehicle. Additionally, this material has passive corrosion resistance ensuring a long life of operation. The body (exterior) of the bot is made of glass fibre reinforced polymer (GFRP) composite. This material has excellent performance characteristics such as lightness, high strength, flexibility in design, good antishock performance, and fatigue and corrosion resistance, as well as good protection and concealment function. Due to the complexity in shape of the body, the manufacturing process of the GFRP composite is ideal for manufacturing the body of the bot. The body has a uniform thickness of 5 mm which also houses O-rings and has special provisions to drill holes and provide space for the placement of bolts and inserts. For mass production capabilities, the usage of this material is in-efficient from the time domain perspective. It takes about 6-8 hours to produce one single part using this technique and requires additional post-processing activity to be done on the body, adding to about another 3 hours. The appropriate replacement material for GFRP for mass production would be HDPE plastic, using the injection moulding manufacturing process. This process reduces the time of manufacturing to about 30- 50 mins and requires minimal post-processing activity.
Sealing and waterproofing of the robotic system is the most important aspect of design and implementation. The robotic system is sealed using ISG O-rings that are made of natural rubber (Butyl rubber). This material is naturally resistant to water and has high strain capacity making it ideal for filling in grooves and irregularities in the body of the robotic system. The o-rings are immersed in a hydro-phobic gel that fills in the gaps not covered by the o-ring (if any). The o-ring of diameter 1mm has been chosen to seal the robotic system.
Another embodiment of the present invention is directed towards the electrical wiring system, as depicted in the figure 2. The total installed power requirement of the robotic system during operation is 1400W. The power requirement takes into consideration the continuous operation of all the sensors, the microprocessor (2), the microcontroller (1), the thrusters (6a, 6b, 6c), the micro-pumps (7) and the brushless DC motor (23). The actual power requirement by the electrical components and sensors is 350W, and that of the thrusters (6a, 6b, 6c), the micro-pumps (7) and the brushless DC motor (23) is 1050W. The electrical wiring system uses two voltage regulators (21), the power distribution unit (3) distributes the total power from the power source (4) into the microprocessor (2) and the thrusters (6), in which the microprocessor (2) and the thrusters (6) are placed in electrically series connection.
The power needs can be broadly classified into two parts: the microprocessor (2), preferably, Intel NUC and the thrusters (6a, 6b, 6c). The other electrical components can be powered through USB power from the microprocessor (2). The voltage and current requirements are different for the microprocessor (2) and the thrusters (6a, 6b, 6c), so the power flowing out from the power source (4) has to be distributed as such. To divide the voltage, the microprocessor (2), and the thrusters (6a, 6b, 6c) are placed in serial. This causes the total current flowing through both the same. Active power regulating components are added which prevent short-circuiting. Active components which actively regulate power, passive design is to break the voltage and current in parallel and series necessarily to distribute it to components (wattage in series or parallel concepts too).
The robotic system features the power source (4) comprises of two batteries of a massive battery capacity of '22000mAh 6S 14.8V 25C' and '22000mAh 6S 22.2V 25C' respectively,preferably, LiPo batteries are used in the present invention to power the robotic system as these batteries have the highest specific energy storage and are commercially available. The electronics and sensors used in the present invnetion are powered by a LiPo battery of which is kept separate from the battery powering the thrusters (6). This is designed such that the maximum current drawn from a single battery does not exceed its C rating ensuring the safety of the robotic system.
The battery compartment and electronics compartment are two separate IP68 rated casings and are interconnected by subsea wires and connectors. The robotic system features two types of connectors - dry-mate and wet-mate. Dry-mate connectors are being used for connections inside the robotic system and wet-mate connectors are being used for external connections. These connectors are of Fischer Connectors make and have a robust steel body. Additionally, they have gold plated pins that prevent corrosion of the tips. The connectors are being used for data transfer, debugging and power transmission. The power transmission connectors used in the robotic system have a maximum of 5A current rating. The number of pins in the connectors used ranges from 3 to 12.
Another embodiment of the present invention is directed towards the battery management system, as depicted in the figure 3. The battery management system is broadly divided into seven different sections - 1) Cutoff MOSFETs (27a, 27b), 2) cell voltage monitors, 3) cell balancing circuits, 4) Real time clock (RTC), 5) temperature monitor system, 6) current monitor, and 7) microcontroller. The battery management system (24) comprises of: (i) a cut-off MOSFETs section comprises of a MOSFET (27a) for charging and a MOSFET (27b) for discharging, in which the MOSFETs (27a, 27b) are controlled with a microcontroller (25); (ii) a cell voltage monitor, which when detects charging voltage at a charging circuit (28), and sends signals to the microcontroller (25) to close the MOSFET (27b) and to connect the power source (4) to the charging circuit (28); when detects voltage at the power source (4), sends signals to the microcontroller (25) to close the MOSFET (27b) and to connect load (32) to the power source (4); (iii) a current monitor (29) comprises of current sensor amplifier put in shunt configuration and detects the current coming in and out of the power source (4); (iv) a cell balancing circuit (30) to measure voltage of each cell; (v) a Real Time Clock (26) in conjunction with the microcontroller (25) is used to calculate the estimated time left for full charging; and (vi) a reverse current protection diode (33). The Cutoff MOSFETs (27a, 27b) which act as switches and control gates control the flow of charge from battery to the loads (32) and from charging circuit (28) to the battery. There are two MOSFETs one for handling charging (27b) and one for discharging (27a). The MOSFETs (27a, 27b) are controlled with the microcontroller (25). According to the cell voltage monitor, the robotic system possesses 2 bus architecture, where the charging and discharging switches are not connected. The charging connector to the battery pathway and connection of load (32) to the battery are different. If the voltage monitor detects appropriate charging voltage at the charging circuit (28) input, the microcontroller (25) closes the discharging MOSFET (27b) and the battery gets connected to the charger. Similarly, if appropriate voltage is found to be at the battery, the microcontroller (25) closes the charging MOSFET switch (27a) and load (32) is connected to the battery. This allows for simultaneous usage and charging as well. To prevent overcharging, output voltage of individual cells as well as total influx of charge has to be measured. There is a current monitor (29) in place that monitors the current coming in and out of the battery. Charge is then calculated as the integration of current over time. In this way the charge of the cell is monitored. The current is measured through the use of a current sensor amplifier which is put in shunt configuration, i.e. parallel to the wire connected to the battery. The current sensor amplifier also feeds in the data to the microcontroller (25) so that the microcontroller (25) could perform the integration and monitor the total charge that goes into the battery so that it does not overcharge. Separate voltage monitors are placed in order to measure the voltage of each cell. Each cell has to be monitored as the cells do not always charge and discharge evenly. This reduces the battery health in the long run. Cell balancing is done to even out the amount of charge in every cell. Passive cell balancing technique is used to balance out the charge. A dummy load is put in series with the cell and a MOSFET switch connected with it. When a cell is excessively charged the cell voltage monitor connected to the microcontroller (25) signals the microcontroller (25) to close the MOSFET switch (27a, 27b). Once the circuit is closed, the cell disperses energy through the connected resistor. When the said voltage level is achieved, the MOSFET switch (27a, 27b) is opened again. The Real Time Clock (26) in conjunction with the MOSFET switch (27a, 27b) and data from various sensors acts as the logbook of the battery. This data is further used to calculate the estimated time left as well battery health deterioration. The temperature sensor (12) is present to prevent any thermal runaway condition. In case the temperature goes above the prescribed value, it instructs the microcontroller (25) to close off the charging MOSFETs (27b) or the discharging MOSFETs (27a,) whichever one is in use.
Another embodiment of the present invention is directed towards the he array of onboard sensors help the robotic system perceive the environment it’s currently operating in, in terms of its physical size and shape, chemical composition and presence of foreign material. The sensor stack responsible for this includes-
(i) The Inertial measurement unit sensor (15): The inertial Measurement unit or IMU (15), measures and reports the forces acting on a body, its angular rate and orientation in both translational and rotational frames. These are often paired with sensor fusion technology to provide accurate pose and heading information. The SparkFun 9-axis Inertial Measurement Unit (IMU), comes with a Bosch BNO080 3-axis accelerometer, 3-axis gyroscope and a 3-axis magnetometer along with a 32-bit ARM Cortex M0+ processor that combines and corrects the drift-error, providing accurate IMU information allows to sense orientation and motion.
(ii) The Water pressure sensor (14) detects the water pressure at any given point and is primarily used for determining the depth in which the robotic system is currently at. The sensor is the Measurement Specialties MS5837-30BA and measures up to 30 bar (300m/1000ft depth) and communicates over I2C. It operates on 3.3V I2C voltage but can accept power input up to 5.5V. It comes standard with a 4-pin DF13 connector that is compatible with the Intel NUC. This lets the robotic system maneuver swiftly from position to position by detecting and storing the depth data at each point of stabilization.
(iii) The Ultrasonic sensor (16): Particles in the water can cause refraction, scattering and absorption, which can degrade any electromagnetic signals. Mechanical waves on the other hand, propagate by exerting pressure on the medium. This makes the use of sound waves ideal for underwater detection and ranging. The MaxBotix MB7072 MaxSonar has a 20-765cm detection range with a refresh rate of 10Hz. With a robust housing that meets the IP68 water intrusion standards, and multiple simultaneously active interfacing options, including RS232, made it a perfect fit for the robotic system’s application.
(iv) The Leakage sensor (13): Operating an underwater robot adds the added requirement of protecting the electronics and the computing setup from leakage. This is achieved using a series of exposed traces, that carry ground and sensor signals, and a capacitive change is monitored. This has an operating voltage of 4.75v-5.25v at 20mA, with a 10-30°C operating temperature, making it suitable for underwater operation. This output both digital and analog signals, making reading and processing signals much efficient.
(v) The Camera (17): The camera is an optical instrument used to relay visual information, providing the system under consideration with vision. The new found machine-vision opens the opportunity to tap into an endless set of information, making the system more robust and efficient. The ELP Sony IMX415 HD Camera, with the Sony IMX415 1/2.8” image sensor, streams images at a maximum resolution of 3840*2160 and videos at a resolution of 3840*2160 at 30 Frames per second. With a 94.5deg field of view and 8 white LED’s, this model performs the best underwater. The camera (17) is mounted on the robotic system using a mounting pad of ¼” - 20 screws. Although the camera (17) is not intended to work underwater, it is protected by an IP68 transparent housing, making it a waterproof casing.
(vi) The Chemical Sensors: The sensors used for maintaining pool’s chemistry and sanitization are as follows:
1) pH sensor (10) - Techtonics pH sensor has a single cylinder that allows direct connection to the input terminal of a pH meter, controller, or any pH device which has a BNC input terminal. The pH electrode probe is accurate and reliable that can give almost instantaneous readings. This Kit is integrated to the Arduino controller (cluster) and it has an LED which works as the Power Indicator, a BNC connector and PH2.0 sensor interface. For taking the dynamic data values, the pH sensor is attached to the with BND connector, and plug the PH2.0 interface into the analog input port of any Arduino controller. It is pre-programmed and formulated to give the alkalinity measures as well when the robotic system receives pH values to formulate the chart in defined pattern to analyze and produce comprehensive reports along with live health status of the swimming pool on the supporting application at the end of the operation. The data is fed in from the different locations in the swimming pool to have variable pH comparison at major hotspots inside the pool.
2) Temperature sensor (12) - Robot Banao waterproof digital temperature sensor has -50 ~ +125 accuracy over the range of -10â°c to +85â°c: 0.6â°c and is directly integrated with the arduino cluster microcontroller (1). The integration does not require any mid-way connectors and thus speed of plotting the graph and analysis of the future variable LSI ranges due to temperatures becomes very quick and dynamic.
3) Total dissolved sensor (9) - SEN0244 by DF robot supports 3.3 ~ 5.5V wide voltage input, and 0 ~ 2.3V analog voltage output, which makes it compatible with 5V or 3.3V control systems or board. The excitation source is an AC signal, which can effectively prevent the probe from polarization and prolong the life of the probe, meanwhile, increase the stability of the output signal. The TDS probe is waterproof; it can be immersed in water for long time measurement and allows a simpler interface with the microcontroller (1) thereby sourcing maps for report generation.
Another embodiment of the present invention is directed towards the autonomous operation and navigation of the robotic system, as shown in figure 4. The objective of eliminating human intervention in the process of cleaning and maintaining a pool is achieved by the methodologies described in this process.
a) Mapping: The mapping phase of any mobile robotic system, that is considered to be intelligent, independent and autonomous, deals with the development of an accurate 3 dimensional model of the environment that it operates in. All automated tasks to be performed by the mobile robotic system take into consideration this model of the environment. Most importantly, successful navigation of the robotic system within the environment, in terms of the trajectories planned, requires an effective navigation strategy to be employed upon the map that was built. This heavy dependency on the map requires it to be precise, dynamic and must include all information relevant to the operation, making map building a rather complex process. The robotic system in consideration develops a 3D occupancy grid map based on the octree tree data structure, which divides the 3-dimensional space recursively into eight octants enabling the system to model an arbitrary environment without providing any prior information. The map shows a clear distinction between occupied areas, free space, and unknown areas as well as providing means to update the map at any time. The approach is implemented using the OctoMap library, octomap_ros, available for the robotic Operating System framework. This requires the environment to scan data as PointCloud or PointCloud2 message types, as specified under the sensor_msgs package. The sensor_msgs package defines messages and its structure for commonly used sensors, including rangefinders. The key steps taken include sourcing the different sets of data related to the environment, manipulating them, making intelligent approximations to its coexistence and finally aggregate the different data into one final map. The data sourcing stage involves the collection of spatial information. The system operates underwater and poses a major threat to the use of electromagnetic wave-based rangefinders, owing to its refraction and scattering. Hence, a mechanical wave-based range finder is employed, namely an ultrasonic sensor. This provides the system with occupancy information in its plane of existence, i.e. in 2 dimensions. The rangefinder outputs information in the sensor_msgs/LaserScan data format. Creation of an OctoMap requires the data to be published over the sensor_msgs/PointCloud. Hence, the data stream must be published correctly from sensors over ROS as it is important for the Mapping technique and the navigation strategy to operate effectively. The laser_pipeline meta-package is a library for processing laser data, including it’s conversion into 3D representation. This library is employed to remap the spatial information from type LaserScan to PointCloud streams. Since the data accumulation stage is limited to 2D spatial information and the map being built is 3 dimensional, the occupancy in the 3rd dimension is set to ‘unknown’. This allows for the flexibility of updating the map when the system finds itself in a plane in close proximity to an area of unknown occupancy. The motion of the system within the area under consideration requires the map building process to have an idea about the current position of the robotic system. The Inertial Measurement Unit along with the motion encoders, provides a very accurate estimation for this purpose.
b) Autonomous Navigation: Once the map is built, the robotic system must be able to navigate the mapped environment. The trajectories planned play an important role in the efficient operation of the system. The objective is to first map the surface of the pool and then move on to the bed. This gives an estimate of the perimeter of the environment under consideration. Next, the robotic system must move into the depths, to perceive the environment as well to generate the first chemical composition report.
i) Surface Navigation: The main purpose of the wall is to remain parallel to the pool wall surface (or it’s tangent) while moving in a certain direction. To remain parallel means to remain in a fixed distance from the wall. If the robotic system encounters discrepancies in the distance reading while moving, it can correct it’s motion, to accommodate the change in distance whether positive or negative and stay parallel to the wall in its course.
ii) Underwater Navigation: Once the robotic system navigates the surface, the map building process requires it to move into the depth. The trajectories planned will be such that during the mapping process, the aim is to converse maximum space (volume). But during the cleaning process, the aim is to traverse through areas of higher demand in terms of cleaning required. Potential field approach is ideal for this operation.
All the navigation units give data of where to move next to the control system unit, which parses the navigation data, which is basically the information as to where to move next and converts to commands for the controllable units that are the thrusters (6). The control system understands how locomotion happens and what the controllable units are. The robotic system movement control only happens through the thrusters (6) which are in this case the controllable units. To achieve the desired motion, what should be the next change to the state of the thrusters (6) is controlled through the control system node to control the electronic speed controllers (5).
(c) Obstacle Avoidance: The prerequisites while mapping is that the pool is clear of humans and other pieces of the equipments. There is two-way communication between the obstacle avoidance unit and the mapping unit. The obstacle avoidance unit is an extra precautionary measure so as to not record any human or any piece of equipment as a fixture and put it on the map.
Another embodiment of the present invention is directed towards chemical cleaning through calculation of the Langelier Saturation Index by the robotic system. The robotic system has an inbuilt Langelier Saturation Index calculator which maintains the pool in the Langelier Saturation Index range of -0.3 to +0.3, in which the calculation of the alkalinity and calcium in the pool, comprises the steps of:
- the robotic system checks alkalinity below 4.3pH through the pH sensor (10) without taking carbonic acid into account;
- the robotic system checks buffer of carbonate ions above 8.3pH through the pH sensor (10) and treats it as total alkalinity of the pool;
- the robotic system prescribes the quantity of acid required to be dosed to bring the pH levels back to normal range of 7.4-7.6 pH to maintain the Langelier Saturation Index in range; and
- using the carbonate alkalinity algorithm, the robotic system analyze the over saturation of water with calcium; and
- the robotic system captures live pictures of the tiles of the pool through the camera (17) and audits for a whitish line being deposited on the surface of the tiles, and sends a signal to the microcontroller (1) to load the scale treating reagent to discharged in the water through the chemical store (8) in a prescribed dose.

The Langelier saturation index (LSI) is an objective measure of water balance or an index on mineral saturation which shows how much water can hold, before the minerals start falling out. It is a standalone parameter which allows the pool water to be in perfect chemistry with all its chemical constituents being relatively balanced according to the quantity of other chemicals present inside water. The robotic system has an in-built LSI calculator that is responsible for maintaining the pool in the most optimal LSI range of -0.3 to +0.3. Here the robotic system takes all six factors into account, calculates the LSI range of the pool water and determines the behavior of water by predicting the corrective range and discharging them in the desired quantities to give the most optimized pool. These six factors are as follows:
? Alkalinity- The robotic system takes into account any constituent inside the water that can either accept or release an H+ ion where it refers to the composition of all such constituents as an alkalinity buffer, significantly in-regard to the considered swimming pool. As per the Figure 6, the robotic system checks for alkalinity below 4.3 pH (after formulating it on the digital scale through pH) and it does not take Carbonic acid (H2O+CO2) into account while performing its initial analysis to prescribe desired dosing operations to have the LSI, into the range because carbonic acid (H2CO3) does not have the capacity to accept H+ ion and that’s why robotic system is not considering it under the alkalinity buffer. The pH starting from 4.3 enables the alkaline constituents to accept and leave H+ ion and this is considered under alkalinity criteria by the robotic system. Beyond 8.3 pH, there is only Carbonate left and the robotic system takes into account the buffer of carbonate ions present along with bicarbonate ions (in respective pH ranges) and treats it as total alkalinity of the pool. By this data, robotic system considers in prescribing the quantity of acid (muriatic acid, on-board) required to be dosed to bring the pH levels back to normal i.e., 7.4-7.6 for maintaining the LSI, in range.
? Calcium: The amount of carbonate present determines the formation of calcium carbonate as particles of CO3- and Ca2+ combine together. Using the carbonate alkalinity algorithm, the robotic system is able to analyze if the water is over saturated with calcium and would start evaporating or throwing out the mineral content to the surroundings, leading to another commonly occurring problem of scaling. Through on-boarded camera (17), the robotic system captures live pictures of the tiles and audits for a whitish line being deposited on the surface of the tiles, and recommends to load the SC-1000 (scale treating reagent) to be discharged in the water through the chemical chambers of the chemical store (8). The sensor data complemented by the camera’s (17) image processing, jointly quantifies the amount in which SC-1000 is required for the 3-D mapped pool volume, to combat scaling. If the images processed show no scaling/calcium carbonate deposition but wearing/etching away of the tile surface, the same is double checked with the sensors (carbonate alkalinity) to prescribe if the infrastructure may get damaged due to lack of calcium inside the pool water. Calcium is then added to the pool, through the robotic system’s chemical dispenser after quantifying the amount for the same through globally accepted formulae. If the tiles are overly damaged already at the time of infrastructural audit performed by the robotic system, the same is show cased through the report generated by the supporting application which uniquely prescribes the possible measures to be taken by the pool authorities to counter the issue. Carbonate alkalinity (pre-dominant factor in determining the scale and etching issues inside the pool) gets calculated through the back-end algorithm and here is a general formulation of carbonate alkalinity that is taken into account while quantifying the calcium dosing or excess presence:
Total Alkalinity (as calculated by the sensors) = CYA (cyanuric acid in ppm)/3 + Carbonate alkalinity
Through the above formula, the robotic system prepares a graph on the pattern in which calcium would reside in stable conditions inside water and at which period of time another calcium dosing would be required (seasonal). The same is recommended through the CRG (comprehensive report generation along with live health status of the swimming pool) by the supporting application, for user’s reference.
? pH- The sensors blend data on the principles of Henry law, which in case of swimming pool water concludes few important parameters. The type of pool (fiberglass, salt-water, cemented) and the natural environment (hot, cold, moderate) also determine the pH graph and the pattern in which it varies over a time interval of day, week and months. The pH sensor (10) formulates a graph on each pool cleaning cycle to identify, apart from the organic and inorganic, dissolved and undissolved constituents, what majorly accounts for the change in pH of the particular pool water. The robotic system takes into account the type of pool as mentioned above and using AI enables itself to quantify the right quantity of cyanuric acid which shall bring down the pH in the most optimized range as shown in the Figure 7.
The robotic system takes into consideration all those constituents, acidic or basic, which are to be dispersed in the pool such as trichlor or liquid chlorine, for sanitization objective, which may bring about a change in the pH levels of the pool and accordingly prescribes the quantity of such chemicals and releases them into the pool through its pressure chemical chamber.
? Temperature- Water temperatures are measured for one cycle of operation and consecutive cycles thereafter by the on-board sensor. The temperature sensor (12) maps a relative graph where it depicts if temperature is one of the dynamically moving and pre-dominant factors for the specific pool which is causing a change in LSI. The graph also depicts a future where LSI correction may be required in winters during and after closing. This is because calcium requires to be dosed in, at lower temperatures, in order to prevent LSI violation that causes dust and protruding crystal formation (etching of the bottom and walls of the pool) at the time of opening the pool.
? Total dissolved solids (TDS) - Total dissolved salts/solids sensor (9) is on-board which keeps a track of linear figures obtained after the pool is treated more than five to six times. The robotic system ideally cleans one pool, twice a week. So, the final TDS reading obtained post each cleaning cycle gets stored in the database and a pictorial graph is prepared every three weeks which actually prescribes the need of draining, physically diluting, reverse osmosis and refilling the pool, exactly when it is required. This prevents over running the pumps for diluting the pool and refilling it at odd intervals, saving a considerable amount of energy and time. Also, it helps in keeping the water novice for a longer period by preventing too many such operations of diluting and draining which result in ageing or saturation of the pool after which, actual refilling or change of the whole lot of the pool water is required.
? Cyanuric Acid (CYA) - It is the last factor which is taken into consideration once the 5 parameters listed in the Figure 8 are stabilized according to the LSI by the robotic system. The amount of carbonate alkalinity and chlorine (sanitization column) are largely impacted by the amount of CYA discharged by the robotic system, in the pool. The robotic system thus refers to the standard range of CYA relative to the amount of other five parameters and discharges CYA to note a considerable change in the LSI. Future addition quantities for each pool are managed according to the final change in LSI scale, which CYA brings about.
Another embodiment of the present invention is directed towards chlorine cleaning by the robotic system. The cleaning methodology of chlorine follows by the robotic system, comprising the steps of:
? the robotic system checks the level of chlorine in the pool on immersion;
? the robotic system starts to map the pool edge;
? the robotic system dispenses regulated amounts of chlorine as a test is below the Residual level;
? the robotic system estimates the consumption of Chlorine based on rate of reaction and pool size;
? the robotic system determine the RRC (Remaining Required Chlorine), which is the amount of chlorine required to neutralize the Chlorine Demand;
? the robotic system dispenses required chlorine or alerts the Field Agent;
? If the estimated RRC is well below a set Threshold, the field agent is alerted to drop a pre packaged dosage;
? Once Demand is neutralized the Buffer Chlorine Amount (BFA) is determined based on size of pool;
? BFA or equivalent is dispensed by the robotic system in the pool to maintain 1-3 ppm of residual requirement; and
? Constant 12 point check completed at the end and chlorine is balanced if required.

Another embodiment of the present invention is directed towards the buoy (18) used for communication in the robotic system. To achieve underwater communication, the buoy (18) is setup. The buoy (18) remains at the surface and houses the router (19) that facilitates the inter-system communication and also acts as a gateway to the internet. The inter-system communication is a mixed network, consisting of a wireless network between the buoy (18) and the ground station (20) along with a wired connection between the buoy (18) and the robotic system. The buoy (18) has a router (19) that supports both wireless networks via wifi and wired networks via ethernet. The router (19) assigns both devices a static IP address, which can be referenced for inter-system communication. The wired connection is realized using an ethernet cable which takes the data forwarded to the underwater the robotic system from the router (19). This could be packets sent from the ground station (20) or from nodes beyond the network, i.e. the internet.

Another embodiment of the present invention is directed towards the end user engagement use-case where the robotic system is enabled to provide features as mentioned below:
? ‘Let’s Race’ - The robotic system swims along with the user by replicating his trajectory, parallel to his path of swimming and captures his pool strokes through the camera to smartly identify the swimming style. Here, the robotic system reconsiders itself to reach one of the end points of the 3-D mapped pool along with a specific user/swimmer who is identified through the camera on-board and wishes to use the robotic system for recreational purposes. This is implemented using a pose estimator to estimate the pose of the swimmer in discrete intervals. The estimated pose is passed through a specifically trained object detector to match those to ‘key-poses’ and make a count of the strike rate. This data generated can be used to recommend better techniques as well.
? ‘Serve Drink’- The robotic system is capped with a dynamic payload which has dual circular partitions that can carry a beverage stored in a can /glass of 330ml to 568ml of volume. The user can command the robotic system for a drink and through a combined algorithm of voice recognition and image processing where the robotic system maneuvers to one particular corner of the pool which is nearest to the human attendant outside and display order to load the exact specification of the drink on it after which the robotic system moves back to uniquely identify the user who ordered the drink using its imaging processing characteristics and serves the drink to him at the same position from where the order was made or a different position, inside the pool. Visual gestures will be the primary way of interacting with the robotic system. The 3840x2160 pixel CMOS Sony IMX415 camera on the robotic system will be serving dual purposes of detecting and understanding the position of a person inside the pool. The localization of the person is necessary as the robotic system has to retrace navigation trajectory for serving the drink. The image processing based approach will identify and isolate all humans within it’s visual periphery and identify their location in the pool. For person recognition, the robotic system uses traditional image processing combined with pre-trained linear HOG (Histogram of oriented gradient) and linear SVM, to detect the person. The pre-trained model is already available with the standard version of OpenCV. We can use that model directly on human detection in the swimming pool. Once a person is detected, robotic system automatically enables ‘Recognise the hand’ functionality (of the person) and initiates hand gesture recognition. External noise being the major concern in this crucial operation cycle is considered by the robotic system where it removes the same using custom refinement methodology based on Gaussian filters. The concluding operation is contour detection where robotic system classifies the hand gesture into one of 10 types using deep learning techniques. These 10 point techniques are shipped with the robotic system, stored in the processor where customisation of the same is also offered through supporting application.
? ‘Snap Time’- The front facing camera and the lightweight robotic system together lets the user capture pictures inside the pool using a button, specially provided for manually operating the camera which gets directly stored on our web server and can be accessed or uploaded to social media channels, as per user’s choice.
Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications can be made without departing from the spirit or scope of the present invention as defined.

CLAIMS:We Claim:
1. An autonomous robotic system for swimming pool, comprises of
- a microcontroller (1);
- an ultra small self-contained microprocessor (2);
- a power distribution unit (3);
- a power source (4) with a battery management system (24);
- a plurality of electronic speed controllers (5);
- a set of thrusters (6) comprises of three thrusters (6a, 6b, 6c);
- an array of micro-pumps (7);
- a chemical store (8) comprises of a plurality of chemical chambers having swimming pool related chemicals and sanitizers;
- a sensor array (103) comprises of a total dissolved solid sensor (9), a pH sensor (10), a chlorine sensor (11), a temperature sensor (12), a leakage sensor (13), a water pressure sensor (14), an inertial measurement unit (15) and an ultrasonic sensor (16);
- a camera (17);
- a buoy (18);
- an underwater scrubber (34); and
- a mesh (39);
- a plurality of brushless DC motor (23)
wherein the sensor array (103), the chemical store (8) via the array of micro-pumps (7) and the thrusters (6) via the electronic speed controller (5) are connected to the microcontroller (1); the microcontroller (1) is connected to the buoy (18), the camera (17) and to the power distribution unit (3) through the microprocessor (2); the power distribution unit (3) backed up with the power source (4) provides power to the microprocessor (2) and the electronic speed controller (5); and the buoy (18) through an internet network (19) and an user interface (20) provides underwater communication to an user.
2. The autonomous robotic system for swimming pool as claimed in claim 1, wherein the thruster (6c) is located in the centre of the robotic system coincides with the centre of gravity to help the robotic system to dive underwater and navigates inside the pool and the thrusters (6a, 6b) navigates the robotic system in the horizontal plane in surge and yaw motion in which:
- when the two thrusters (6a, 6b) have the forward polarities, the robotic system moves in forward direction, parallel to the axis of rotation of the thrusters (6a, 6b);
- when the two thrusters (6a, 6b) have the reverse polarities, the robotic system moves in reverse direction, parallel to the axis of rotation of the thrusters (6a, 6b); and
- when either of the thrusters (6a, 6b) have opposite polarities, then the robotic system rotates about an axis perpendicular to the plane of axis of the rotation of the thrusters (6a, 6b).

3. The autonomous robotic system for swimming pool as claimed in claim 1, wherein a working mechanism of the thruster (6c) for cleaning the algae in the pool, comprises the steps of:
- the orientation of the thruster (6c) locates in concentric circles with a bottom scrubber (34) to provide a rotation to the thruster (6c);
- the rotation of the thruster (6c) creates a localized vacuum, when the thruster (6c) is powered in a forward polarity; and
- the localized vacuum sucks the algae and other micro-macro particles and stores in a mesh (39) which is clamped to the body of the robotic system and covers the exit portion of the thruster (6c).
4. The autonomous robotic system for swimming pool as claimed in claim 1, wherein a surface cleaning mechanism of the robotic system, comprises the steps of:
- the front-facing camera (17) detects a location of the suspended macro-particles on the surface of water and sends a signal identifies the relative position of the particles from the robotic system to the microcontroller (1) via the microprocessor (2);
- the microcontroller (1) commands the thrusters (6) to propel the robotic system towards the location of the particles; and
- the mesh (39) equipped with the robotic system collects and hold the suspended particles during the cleaning operation of the robotic system which is partially submerged in the water for aiding in the capturing of the particle into the mesh (39).
5. The autonomous robotic system for swimming pool as claimed in claim 1, wherein chlorine, algaecides and stabilisers are stored in the chambers of the chemical store (8) in which the chambers of the chemical store (8) have an inlet opening and an outlet hose and each of the outlet hose is attached to the inlet of the micro-pumps (8) which has a bore of 2.4mm and are powered by a brushless DC motor (23) and the speed of the discharge of the micro-pump (8) is controlled by the microcontroller (1).
6. The autonomous robotic system for swimming pool as claimed in claim 1, wherein the underwater scrubber (34) is made of plastic and houses a series of nylon bristle strands (35) grouped together and are uniformly distributed over the surface of the scrubber (34) in concentric circles; has a through hole at its centre and is concentric with the central thruster (6c); and houses an internal gear meshes with a pinion coupled to a shaft of the brushless DC motor (23) controlled through the electronic speed controller (5).
7. The autonomous robotic system for swimming pool as claimed in claim 1, wherein the working mechanism of the robotic system for scrubbing the wall and bed of the pool to remove algae, comprises the steps of:
- the camera (17) captures images in a continuous frame and sends to the microprocessor (2) for detection of algae hotspots by image processing through the microprocessor (2); and
- the central through-hole of the underwater scrubber (34) concentric with the central thruster (6c) and then sucks the scrubbed algae and salts from the walls and bed that gets collected in the mesh (39) of the robotic system.
8. The autonomous robotic system for swimming pool as claimed in claim 1, wherein the power distribution unit (3) distributes the total power from the power source (4) into the microprocessor (2) and the thrusters (6), in which the microprocessor (2) and the thrusters (6) are placed in electrically series connection.
9. The autonomous robotic system for swimming pool as claimed in claim 1, wherein the battery management system (24), comprises of:
(i) a cut-off MOSFETs section comprises of a MOSFET (27a) for charging and a MOSFET (27b) for discharging, in which the MOSFETs (27a, 27b) are controlled with a microcontroller (25);
(ii) a cell voltage monitor, which when detects charging voltage at a charging circuit (28), and sends signals to the microcontroller (25) to close the MOSFET (27b) and to connect the power source (4) to the charging circuit (28); when detects voltage at the power source (4), sends signals to the microcontroller (25) to close the MOSFET (27b) and to connect load (32) to the power source (4).
(iii) a current monitor (29) comprises of current sensor amplifier put in shunt configuration and detects the current coming in and out of the power source (4);
(iv) a cell balancing circuit (30) to measure voltage of each cell;
(v) a Real Time Clock (26) in conjunction with the microcontroller (25) is used to calculate the estimated time left for full charging; and
(vi) a reverse current protection diode (33).

10. The autonomous robotic system for swimming pool as claimed in claim 1, wherein the ultrasonic sensor (16) is used as mechanical wave-based range finder in the robotic system.
11. The autonomous robotic system for swimming pool as claimed in claim 1, wherein the inertial measurement unit (15) is used in the robotic system to trace motion and current position of the robotic system.
12. The autonomous robotic system for swimming pool as claimed in claim 1, wherein the robotic system has an inbuilt Langelier Saturation Index calculator which maintains the pool in the Langelier Saturation Index range of -0.3 to +0.3, in which the calculation of the alkalinity and calcium in the pool, comprises the steps of:
- the robotic system checks alkalinity below 4.3pH through the pH sensor (10) without taking carbonic acid into account;
- the robotic system checks buffer of carbonate ions above 8.3pH through the pH sensor (10) and treats it as total alkalinity of the pool;
- the robotic system prescribes the quantity of acid required to be dosed to bring the pH levels back to normal range of 7.4-7.6 pH to maintain the Langelier Saturation Index in range; and
- using the carbonate alkalinity algorithm, the robotic system analyze the over saturation of water with calcium;
- the robotic system captures live pictures of the tiles of the pool through the camera (17) and audits for a whitish line being deposited on the surface of the tiles, and sends a signal to the microcontroller (1) to load the scale treating reagent to discharged in the water through the chemical store (8) in a prescribed dose.
13. The autonomous robotic system for swimming pool as claimed in claim 1, wherein the cleaning methodology of chlorine follows by the robotic system, comprising the steps of:
- checking the level of chlorine in the pool on immersion;
- mapping the pool edge;
- dispensing the regulated amounts of chlorine as a test, below the residual level;
- estimating the consumption of Chlorine based on rate of reaction and pool size;
- dispensing the remaining required chlorine for neutralizing the Chlorine Demand;
- alerting a filed agent a pre packaged dosage, if the estimated remaining required chlorine is below a set threshold.
14. The autonomous robotic system for swimming pool as claimed in claim 1, wherein the buoy (18) is placed at the surface of the robotic system and houses the router (19), facilitates the inter-system communication with a ground station through the user interface (20).