Pool cleaning method and apparatus

ES 2 234 962 T3

DESCRIPTION

Procedure and apparatus for cleaning swimming pools.

Scope of the invention

The present invention relates to robots for cleaning swimming pools. More particularly it relates to an apparatus and a method for cleaning the bottom of a swimming pool.

Background of the invention

There are many types of automatic pool cleaners available, featuring various capabilities and navigation modes to clean the bottom of the pool.

For example, in the American patent US No. 6,125,492 (Prowse), entitled automatic device for cleaning pools, an automatic device for cleaning swimming pools is described, which includes a flexible cleaning element designed to come into contact with the surface of the pool below the water. A tube is coupled to the cleaning element to connect the cleaning device to a water vacuum hose through a hose adapter. Water and contamination from the pool surface are drawn from below by the cleaning element through the tube by suction to a water filter system before being returned to the pool. A flexible valve element is mounted close to the neck area of ​​the tube so that as water is drawn up through the tube a reduction in pressure in the tube region causes the valve member to flex and momentarily interrupt the flow of water. Interruption of the water flow through the tube results in a momentary ambient pressure differential below the flexible cleaning element which allows the device to move forward incrementally along the underwater surface of the pool. .

US Patent No. 6,099,658 (Porat), entitled High Speed ​​Pool Cleaner Operating Procedure and Apparatus, describes an apparatus and method for cleaning the bottom and vertical side walls of a swimming pool, pond or reservoir using a cleaner. self propelled robot. The robot has a protective housing of conventional design, operating the cleaner at a primary cleaning speed as it traverses the surfaces to be cleaned and until the cleaner housing emerges from the water along the side wall of the cleaner. pool; thereafter the cleaner runs at a secondary speed that is relatively slower than the main speed and thereafter the cleaner reverses direction and descends for a predetermined period of time at the slower secondary speed in order to allow air trapped under the exhaust housing without destabilizing the cleaner during descent. After the predetermined period of time, the cleaner continues to run at the fastest main speed until the cleaner housing again emerges from the surface of the water, after which the cycle repeats.

In US Patent No. 5,086,535 (Grossmeyer et al.), Entitled "Machine and method that uses graphical data for the treatment of a surface", a machine is described for the treatment of a surface area within the contour of a perimeter. including a self propelled frame provided with a surface treatment device mounted thereon. A computer section is mounted on the chassis and a driven wheel (or each of multiple driven wheels) has a motor module for receiving command signals from the computer section. A position sensor is coupled to the computer section to generate a feedback signal that represents the actual position of the machine. A data loading device cooperates with the computer section to transmit data to said computer section. A data file stores the graphical data developed from the graphical description representing the area of ​​the surface to be processed as well as other data developed in other ways. The data file works in conjunction with the computer section and transmits graphics and other data to it. The computer section is arranged to process the data and the feedback signal and generate command signals in response to each of the engine modules. Such modules, and the motors controlled by them, propel the machine over the area of ​​the surface selected to be treated.

The American patent US 5,569,371 (Perling), entitled system for navigation and submerged control of a mobile filter for swimming pools, describes a submerged navigation and control system for a robot for cleaning pools, provided with a drive, a propeller, a filter and a processor to control the drive and a circuit to produce a signal. The system additionally includes a signal detection circuit mounted on the pool, an interface placed on the ground in the vicinity of the pool and comprising a detector to receive and process the data from the detection circuit and to transmit signals to the robot processor. . The determination of the real location of the robot is carried out by means of triangulation in which the stationary triangulation base is defined by at least two separate signal detectors and the vertex of the mobile triangle is constituted by the circuit that produces the signal. carried by the robot.

US Patent No. 5,197,158 (Moini), entitled "Pool Cleaner," describes an automatic vacuum-actuated pool cleaning device provided with a hollow housing supported on two pairs of drive wheels of the device. The housing includes a central water suction chamber in communication with the water flow with the water suction through the bottom of the housing and in communication with the water outlet with an external vacuum pipe, a gear train for drive one of the pairs of drive wheels and articulated directional control floats. The water suction chamber houses a shaft-mounted turbine wheel that supports water-driven blades with the turbine rotating in only one direction by the flow of water through the chamber. The turbine shaft supports a turbine power output drive gear which is meshed with one or the other of two shift gears which in turn inversely drive the gear train as indicated by the position of the floats. directional controls inside the housing2

ES 2 234 962 T3 to. The floats are displaced within the housing to change the shift gears in response to impact of the cleaning device with an obstruction in the pool floor or by impact of the device against a vertical wall of the pool. Displacement deflection of the control floats reverses the rotation of the drive wheels and thereby directs the movement of the cleaning device on the pool floor.

US Patent No. 4,786,334 (Nystrom), entitled "Pool Bottom Cleaning Process," describes a process for cleaning the bottom of a pool with the aid of a pool cleaner. The pool cleaner moves along the bottom of the pool and collects the material that rests on the bottom of the pool. The pool cleaner is arranged to move back and forth in a straight line, with parallel paths between two opposite pool walls. On the walls, the pool cleaner is turned over by turning half a turn so that, after turning, it will have moved laterally perpendicular to the initial direction of travel.

In US Patent No. 4,593,239 (Yamamoto), entitled Method and apparatus for controlling the movement of an automatically guided vehicle, an automatically guided vehicle is described that detects marks placed at a plurality of points along the route by which moves using at least three sensors, selects the number of detected marks from each individual sensor as a reference value according to majority logic and stops when the reference value agrees with a previously determined value. Cumulative errors, caused by false detection are thus avoided and there is a small cumulative error.

US Patent No. 4,700,427 (Kneppers), entitled Procedure for Automatically Driving Self-Propelled Floor Cleaning Machines and a Floor Cleaning Machine to Practice the Procedure, describes a procedure for automatically driving a self-propelled floor cleaning machine along a predetermined path of motion in a limited area to be worked on. A sequence of path segments stored in data memory is recalled and the machine moves through those path segments. The marks are recognized by at least one sensor and converted into stroke correction control commands that actuate and direct the machine.

American patent US No. 3,979,788 (Strausak), entitled mobile pool cleaning machine, describes a mobile pool cleaning machine by suction extraction of sediments from the bottom of pools that comprises a water turbine that drives a drive wheel in such a way that the machine follows a self-directed trajectory in the bottoms of the pools. The drive wheel is able to rotate around a vertical steering axis to prevent the machine from getting stuck on a wall or in a corner of the pools.

US Patent No. 3,892,282 (Wulc), entitled Random Motion Suction Cleaner, describes a method of moving a self propelled suction cleaner along the bottom surface of a swimming pool.

It should be noted that effectively and quickly covering the bottom (and side walls) of a swimming pool is not a simple task and various tracking algorithms have been devised (for examples, see some of the patents mentioned above) to try to solve and overcome this. complex problem. A contribution to the complexity of the navigation problem is the fact that although a robot is globally programmed to move in straight lines from one side to the other and make precise turns, it is difficult to keep it on such a trajectory and turns are difficult. to steer with precision. In fact, the displacement model of a pool cleaning robot is more likely to deviate as the robot is subjected to different conditions and forces such as its own weight, traction and the weight of its electrical cable, the Underground water currents, different friction forces due to uneven surface elevation or texture, dirt on the bottom, asymmetrically shaped (or even shapeless) pools, and so on. Consequently, all swimming pool cleaning robot navigation algorithms rely on numerous and even repetitive sweeping cycles in order to achieve substantial pool coverage.

When considering irregularly shaped pools, some sweeping algorithms turn out to be inadequate and fail to substantially cover the bottom of the pool.

It is the purpose of the present invention to provide a novel and improved method for navigating a swimming pool cleaning robot on the bottom and side walls of a swimming pool and an apparatus therefor.

Still another purpose of the present invention is to provide a method and apparatus for navigating a swimming pool cleaning robot that allows efficient and rapid cleaning of the bottom and side walls of a swimming pool.

Still another object of the present invention is to provide such a method and apparatus that allows high performance and coverage in cleaning irregularly shaped swimming pools.

Other advantages and aspects of the present invention will become apparent upon reading the present specification and viewing the accompanying drawings.

Brief description of the invention

There is therefore provided, in accordance with a preferred embodiment of the present invention, a method for sweeping the bottom of a pool by a pool cleaning robot initially set at an arbitrary position on the bottom of the pool, according to with the claim

1.

Preferred embodiments of this method are described in dependent claims 2 to 18.

Furthermore, according to the present invention, there is provided a swimming pool cleaning robot according to claim 19.

Additionally, preferred embodiments of the pool cleaning robot are described in dependent claims 20 to 23.

Brief description of the drawings

In order to better understand the present invention and

To appreciate their practical applications, they are provided and referenced in the following figures hereinafter. It should be noted that the figures are provided as examples only and do not in any way limit the scope of the invention as defined in the appended claims. Like components are indicated by like reference numerals.

Figure 1 illustrates the path followed by a pool cleaning robot in accordance with a preferred embodiment of the present invention.

Figure 2a illustrates a sectional view of a pool cleaning robot according to the present invention.

Figure 2b illustrates a bottom view of a pool cleaning robot in accordance with the present invention.

Figure 3 illustrates a plot of propulsive power versus time before, during and after a turning maneuver.

Figure 4 illustrates a schematic diagram of the electrical characteristics of a pool cleaning robot according to the present invention. Detailed description of the invention

The main aspect of the present invention is the provision of a pool cleaning robot with a novel and unique steering mechanism that exploits imparted changes in the angular momentum of a propeller in the robot.

Another aspect of a preferred embodiment of the present invention is the navigation algorithm described in the present invention that introduces a systematic sweep of the bottom of a swimming pool in a predetermined manner.

Pool bottom sweeping can be accomplished by having the pool cleaning robot follow a series of paths across the bottom of the pool, from one side of the pool to the opposite side. After each crossing the robot can reverse, moving a leg (or step) back a predetermined distance, substantially in its previous lane and then turn sideways a previously determined angle of turn and the robot moves to reach the wall, reverse and cross from that wall to the opposite wall. Every time the robot encounters a wall, it will detect this case and count the number of encounters with the wall. After a predetermined number of wall encounters have been counted, the preset leg distance will be changed and the routine continues until the entire area of ​​the pool bottom has been covered.

Reference is now made to Figure 1, which illustrates an example of a path traveled by a swimming pool cleaning robot in accordance with a preferred embodiment of the present invention. It should be noted that the lines with the arrowheads represent the direction of travel of the robot and in order to clearly show the direction of travel they do not overlap, although in fact it is anticipated that the robot will follow its lane in its reverse run. The dotted lines represent the actual path the robot is supposed to travel on.

A bottom of the rectangular pool 10 is shown, with four surrounding walls arranged in two pairs of parallel opposite walls (12, 14, 16, 18).

In a preferred embodiment of the present invention the systematic pool bottom sweeping procedure is as follows: a pool cleaning robot 20, typically provided with a motor-driven endless caterpillar drive (but other types are also possible drive), is initially set to begin to cross in a straight path 22 at the bottom of pool 10, beginning its journey to the side of the adjacent pool wall 14. The starting position can be chosen arbitrarily, even something in the middle of the pool. In polygonal pools, such as the rectangular pool depicted in figure 1, it is recommended to initially place the robot near one side of the wall (preferably within a distance of 1 to 3 times the width of the robot), keeping in mind the effective cleaning area covered by the robot as it pumps dirt and litter. By "side wall end" is meant one end of a wall on each side, as opposed to its upper and lower ends.

The robot 20 crosses to the other side of the pool, traveling in a substantially straight line 22 over the bottom 10 until it meets the wall 12. Once the robot has met the wall the motor drive is reversed and the robot is driven substantially in the opposite direction. After a leg of a predetermined length 24 has been moved, the robot turns sideways a predetermined angle 26 (substantially at a right angle in the example of Figure 1) and then travels substantially in a straight line until it encounters the wall 16. For turns in polygonal pools it is recommended to pretend that an angle is turned in such a way that the robot then crosses perpendicular to the front of the pool, but this is not a mandatory requirement.

When meeting the wall the drive motor if the robot has been inverted again and after the robot has moved the leg of the previously determined length 24 it is turned back to the side a previously determined angle 26 directing the robot to a pool wall 18.

After a predetermined number of wall encounters the leg length is altered to a new leg length 30 (and then 32, 34), thereby substantially preventing the robot from following the same path it has taken previously, thereby improving its coverage of the pool bottom. Preferably after the leg length alteration the counter is set to zero and starts counting the wall encounters until the same previously determined number of wall encounters have been counted, after which the length of the wall leg is altered again.

Altering the length of the leg the robot has traveled after it has reversed upon encountering a wall can consist of both increasing and decreasing the length. In the example shown in FIG. 1, the length of the leg is increased. The length of the leg can be set to be shortened rather than increased. In such a case the initial position of the robot when starting the pool sweep is preferably approximately half the way through to the wall on the other side.

It should be noted that if the algorithm involves increasing the length of the leg, it is sufficient to increase it approximately half the length

ES 2 234 962 T3 anticipated pool, because after that any further increments will result in the robot moving on a previously taken path. This is not an ultimate requirement since the user can decide to end the sweeping of the pool bottom by the robot at any moment. It is possible to time the robot's operation using a timer switch, thus limiting its movements.

The turn can be taken in either direction (ie right or left) but preferably the same direction of turn is taken throughout the sweeping procedure to ensure effective coverage of the pool bottom.

For a rectangular pool as represented in figure 1, the previously determined number of encounters with the wall counted before the alteration of the leg length is preferably 7, because if the length of the leg is not altered after 7 encounters with the wall the robot can find itself traveling substantially in its previous lanes following the same initial trajectory 22.

The variable leg length that the robot travels after it has reversed gear when encountering a wall can be arbitrarily set. In the example shown in figure 1, the length is increased in steps of constant lengths, but this is not imperative.

The previously determined angle of rotation can also vary in some turns - or in all of them during the scanning process, both in a predetermined way (as previously programmed), or arbitrarily.

A pool cleaning robot according to a preferred embodiment of the present invention can be any robot according to claim 19, further adapted to carry out the steering algorithm described above.

Reference is now made to FIG. 2a which illustrates a sectional view of a pool cleaning robot 40 in accordance with the present invention. A robot housing 42 houses a motor drive 48 for driving the shafts 44 (in the shaft cover 54) on the ends of which the wheels 46 are attached to the endless track rails, a horizontally oriented propeller 52 (for pumping water from the bottom of the pool up into the robot), driven by a pump motor 50, a control unit 56, a central processing unit (CPU) 58 and a sensor to meet the wall 60. The pumped society and litter are collected inside a filter bag that is placed inside the housing along the pump. Power cable 62 passes through housing 42 to provide power to the electrical components of the robot. In other preferred embodiments of the present invention no power cable is provided and instead the robot is battery powered.

Figure 2b illustrates a bottom view of a pool cleaning robot in accordance with the present invention. Twin parallel endless track rails 43 are provided extended and driven by wheels 46.

The robot depicted in Figures 2a and 2b is driven by a single motor (drive motor 48). Generally pool cleaning robots for small and medium size pools are provided with a single drive motor, while twin motor drive is popular in large pool cleaning robots. The single motor drive can be reversed by using a transmission provided to reverse the direction of rotation of the wheel shafts, but it cannot be used to turn the robot sideways. Two different motors are required to maneuver sideways, since each lane is actuated separately, both by stopping one lane and activating the other, as well as by pirouettes (driving the lanes in opposite directions). In order to make a single motor robot turn sideways it is suggested to employ a series of intentional interruptions of the propeller rotation thereby causing the robot to acquire a side-directed deflection moment and thereby travel in that direction. This method takes advantage of the fact that the thrusters are inherently deflected and it has been found by the inventor of the present invention that a series of imparted interruptions in the rotation of the thruster causes the robot to acquire a side-directed moment.

The number of interruptions - which can vary from a single interrupt to a series of interruptions - as well as their cycle and duration are found empirically for each robot and depends on factors such as the weight and type of the robot, the type of pump, the size, weight and turning speed of the propeller, the speed of the robot when driven on its endless track rails, and the desired angle of turn, etc.

It has been found that in a pool cleaning robot weighing 10.5 kg, with a brushless drive motor and a pump that works at 12 V direct current, 18 meters of floating cable and a transformer (commercially available from Tematech Ltd., Afula, Israel, under the trade name "Aquabot" type "Bravo"), in order to rotate at a substantially right angle, the thruster interrupt series is applied with the following parameters: the duration of the series of interruptions was approximately 10 to 20 seconds, during which a series of approximately 15 to 25 interruptions in the operation of the thruster were administered (sequentially switching the stop and run of the thruster), each interruption lasting approximately from 0.5 to 0.8 seconds. Again the fact that these parameters are empirical and that they differ from robot to robot depending on their dimensions and specific characteristics is emphasized as explained before.

Figure 3 illustrates a graph of thruster power versus time before, during and after a turning maneuver. The X axis represents time and the Y axis represents the thruster power status. The part 70 of the graph represents the thruster power as the robot with its thruster energy approaches the wall. In case 72 the robot detects an encounter with the wall and is driven in the opposite direction. A leg of a predetermined length is then moved for a duration of a time 74 (the length is easily determined and is the product of the known speed of the robot for a duration of a predetermined time). Once the length of the leg has been reached (for example 76) a series of n interruptions in the power supplied to the thruster are administered5

ES 2 234 962 T3 days in a cycle and with a predetermined duration. Once it has turned, the thruster power is maintained until the next turning maneuver.

Figure 4 illustrates a schematic diagram of the electrical characteristics of a pool cleaning robot 80 in accordance with the present invention. Powered by a power supply 90, both externally (via a cable) and internally (battery), the pool cleaning robot comprises a reversible drive motor 82 and a propeller motor 84 independently controlled by a control unit 86 . The control unit is connected to a processing unit (CPU) 94 that dictates the operation of the control and therefore the entire robot. The robot has a wall encounter sensor 92 that detects a wall encounter and generates a signal that is received by the processing unit. It should be noted that the event of the encounter with a wall can be detected by a sensor provided in the robot, such as a proximity sensor or a collision sensor, or a sonar sensor and the robot drive motor is switched to the direction reverse. For example, for this purpose you can use a proximity sensor - an optical sensor typically operating in the field of infrared rays - or a rocker sensor, such as a mercury sensor - a sensor actuated by a balanced rocker mechanism that detects the tilt of the robot when trying to climb a wall. Using a sonar sensor can also provide better steering control.

The processing unit is programmed to drive the drive motor and the propeller motor, through the control unit, in a predetermined way following an algorithm as explained with reference to figure 1 and figure 3, by switching the drive motor between forward and reversing modes and applying the interrupt sequence scheme to the drive motor.

An optional GPS receiver 95 that communicates with the CPU can be used built into the robot to allow its position and direction to be determined. The GPS is provided with a floating antenna 97 or an antenna is built into the power cable from the remote power supply unit.

The cases of the encounters with the wall are counted by means of a counter 96 incorporated with a central processing unit of the robot.

It is indicated that the method and apparatus for automatic pool cleaning of the present invention can be implemented in pools of any shape, be it rectangular, polygonal, circular, oval and even those of irregular shapes. The optional step of varying the length of the legs of the present invention ensures that substantially the entire pool floor can be effectively covered and therefore cleaned in a relatively short time.

The apparatus and method for a pool cleaning robot of the present invention allow the bottom of a pool of any shape, depth and size to be covered efficiently and relatively quickly.

It should be clear that the description of the embodiments and the attached figures set forth in this specification serves only for a better understanding of the invention, without limiting its scope as covered by the following claims.

It should also be clear that a person skilled in the art, after reading the present specification, can make adjustments or arrangements to the attached figures and the embodiments described above that will still be covered by the following claims.