AUTOMATIC RAINFALL MEASUREMENT SYSTEM

An automatic rainfall measurement system with a set of control circuitry measures the height of rainwater or any other conductive liquid by means of a plurality of conductors attached to the wall of the container of the system's rain gauge. A rain detector detects falling raindrops and sends an electrical signal to the control circuitry of the rain gauge. Consequently, an electromechanical system rotates the container of the rain gauge from its initial downward facing position to its final vertical position so that the rain gauge starts collecting raindrops and measuring rainfall. After that it stops raining, and the final height of the rainwater is measured, the electromechanical system rotates the container of the rain gauge back to its initial downward facing position so that the rainwater inside the container is drained away by the gravitational force.

TECHNICAL FIELD

The present invention relates generally to devices and systems for measuring liquid level and more specifically to automatic rain gauges.

BACKGROUND OF THE INVENTION

Various dictionaries have presented slightly different definitions for the word “rainfall”. Some dictionaries define the word “rainfall” as the amount of rain that falls in a place during a particular period. A few dictionaries define it as the amount of precipitation usually measured by the depth in inches. Others define the word “rainfall” as the amount of rain that falls. In this patent, the word “rainfall” refers to the latter definition. That is, in this patent, the word “rainfall” only refers to the amount of rain that falls and does not refer to the period during which rain falls.

Rainfall measurement is necessary or useful in some scientific studies and applications such as meteorology, agriculture, water management, etc. There are also applications where it is necessary to measure the level of a liquid in a container or reservoir. The need to measure rainfall or the level of a certain liquid in a container or reservoir has led to the invention of various sorts of rain gauges and liquid level measurement devices and sensors.

Many of the rain gauges, which have been invented so far, comprise a simple graduated tube by which the user can read the height of the rainwater collected by the tube. U.S. Pat. No. 4,106,336 to Clement F. Marley, U.S. Pat. No. 4,644,786 to Jacobsen et al, U.S. Pat. No. 4,665,744 to David G. Smith, U.S. Pat. No. 5,038,606 to Robert C. Geschwender et al, U.S. Pat. No. 5,531,114 to James R. Frager, U.S. Pat. No. 6,363,781 to David G. Moore, U.S. Pat. No. 6,494,089 to Robert C. Geschwender, U.S. Pat. No. 6,609,422 to Robert C. Geschwender, U.S. Pat. No. 7,181,961 to David E. Hill, U.S. Pat. No. 7,159,455 to Willie Burt Leonard, U.S. Pat. No. 7,509,853 to Stephen A. Noe, U.S. Pat. No. 7,543,493 to Robert C. Geschwender, U.S. Pat. No. 9,010,182 to Matthew S. Glenn, and U.S. Pat. No. 9,335,440 to Matthew S. Glenn all are examples of patents which disclose rain gauges with a simple graduated tube by which the user can measure rainwater height. Though useful, such rain gauges generate no electrical signals and therefore, can't be used as rainfall measurement sensors in automatic systems or as remote rainfall sensing devices. Besides, such rain gauges comprise no automatic mechanisms to drain away the rainwater which is collected by them.

Some of the patented rain gauges are optoelectronic rain gauges. Such rain gauges comprise one or several light sources and light sensors together with electronic components, which measure the level of the rainwater in a container or measure rainfall by counting the number of raindrops and measuring their sizes. U.S. Pat. No. 4,754,149 to Ting I. Wang, U.S. Pat. No. 8,054,187 to Douglas Paul Dufaux, U.S. Pat. No. 8,573,049 to John Antony Ware, U.S. Pat. No. 8,746,056 to Jung et al, and U.S. Pat. No. 9,234,983 to Makiko Sugiura are examples of patents which reveal optoelectronic rain gauges. Optoelectronic rain gauges are usually able to accurately measure the height of precipitation. However, such rain gauges need excessive maintenance to work accurately. For example, in such rain gauges, the presence of dust or dew on the surface of the light sources or light sensors will result in malfunctions. Besides, nearby light sources such as car lights or lamps may affect the accuracy of the optoelectronic rain gauges.

A considerable number of patents on rain gauges disclose electromechanical rain gauges. U.S. Pat. No. 3,943,762 to John Baer, U.S. Pat. No. 3,958,457 to James W. Mink, U.S. Pat. No. 4,292,843 to Charles E. Luchessa et al, U.S. Pat. No. 4,644,786 to Hans Jacobsen et al, U.S. Pat. No. 4,836,018 to Charles Dispenza, U.S. Pat. No. 5,138,301 to Jean Y. Delahaye, U.S. Pat. No. 5,245,874 to John S. Baer, U.S. Pat. No. 5,898,110 to Gotthard L. Hagstorm, and U.S. Pat. No. 9,547,106 to Seon Gil Lee et al, all are instances of patents which explain electromechanical rain gauges. In such electromechanical rain gauges, a predetermined amount of rainwater makes a mechanical component of the rain gauge move. Then the displacement of the moving mechanical component is detected by a sensor. The sensor sends an electrical signal to a counter for each continuous displacement of the moving mechanical component, and since each continuous displacement of the moving mechanical component is triggered by a certain amount of collected rainwater, rainfall can be measured by an electronic circuit, which counts the number of the continuous displacements of the moving mechanical component. Some of the electromechanical rain gauges disclosed in these patents are highly innovative and reflect the high knowledge of their inventors in the field of Mechanical Engineering. However, the major problem with these electromechanical rain gauges is that in such rain gauges, the timely motion and the high speed of the moving mechanical component is essential for the accurate measurement of rainfall. Unfortunately, the timely motion and the high speed of the moving mechanical components can be affected by various causes such as, temperature fluctuations, the presence of dust on the pivots or joints, and fatigue. Besides, some of these rain gauges depend on the physical properties of rainwater such as density and temperature. All these factors can affect the accuracy of the abovementioned electromechanical rain gauges.

Some of the patents explain useful electronic rain gauges which do not comprise any mechanical or optic components. Such rain gauges measure rainfall according to the changes in electrical properties of an electrical component such as impedance, capacitance, etc. U.S. Pat. No. 4,583,399 to John E. Walsh et al is the example of a patent explaining a rain gauge which measures the amount of rain fall according to the changes in the impedance of a capacitor with a water absorber inside it. As the absorber inside the capacitor absorbs rainwater, the impedance of the capacitor changes. An electronic circuit measures rainfall according to the changes of the impedance. The major problem with such rain gauges is that the electrical properties of wet materials highly depend on their temperature. In other words, the impedance or resistance of a wet material highly depends on its temperature. Therefore, temperature fluctuations will cause inaccuracies in such rain gauges.

Some of the patents on rain gauges disclose nice electronic rain gauges which measure rainfall by means of piezoelectric sensors and according to the magnitude and frequency of the impacts exerted by the raindrops to the surface of the receiver of the rain gauge. U.S. Pat. No. 8,448,507 to Atte Salmi et al, and U.S. Pat. No. 9,244,192 to Robert M. Cullen et al are instances of electronic rain gauges which measure rainfall according to the magnitude and frequency of the impacts exerted by raindrops to the surface of the receiver of the rain gauge. Such rain gauges are not accurate when the raindrops are accelerated by wind.

A few of the patents disclose interesting electro-thermal rain gauges, which measure the amount of precipitation according to the electric power required to melt and evaporate the precipitation. U.S. Pat. No. 8,505,377 to Roy Rasmussen et al is an example of such patents. The major problem with these precipitation measuring systems is that their energy consumption rate is much higher than that of other precipitation gauges, and such systems are more suitable for measuring snowfall rather than rainfall.

Some of the patents explain rain gauges, which measure the weight of collected rainwater to calculate the height of rainfall. U.S. Pat. No. 7,540,186 to Jeong et al and U.S. Pat. No. 9,588,253 to Li et al are examples of such patents. The accuracy of these rain gauges is usually influenced by temperature fluctuations. Besides, a siphoning system is used in some of these rain gauges to drain away the rainwater when the container of the rain gauge is filled up with rainwater. Consequently, the height of rainfall during the siphoning time is calculated according to the rate of rainfall before the siphoning time. In other words, in such rain gauges, it is assumed that the rate of rainfall during the siphoning time is equal to the rate of rainfall before the siphoning time. Obviously, such an assumption can't be valid for the cases where the intensity of rainfall changes rapidly because of wind.

A few patents describe acoustic disdrometers, which receive the sound signals generated by the impacts of falling raindrops on the receiver of the disdrometer, and process the sound signals to measure the sizes of the raindrops and the intensity of rainfall. U.S. Pat. No. 9,841,533 B2 is an example of an acoustic disdrometer. Acoustic disdrometers are not accurate when the rainfall intensity is high. For example, if some raindrops simultaneously impact the receiver of an acoustic disdrometer, the disdrometer may fail to accurately measure the sizes of the raindrops and the rainfall intensity. Another disadvantage of the acoustic disdrometers is that they are not accurate when the raindrops are pushed by wind.

U.S. Pat. No. 7,584,656 to Senghaas et al discloses a nice rain gauge which uses a plurality of conductivity sensors to determine rain levels. The electronic rain gauge explained in this patent comprises a digital circuit to measure the rainwater level through the conductivity sensors and a solenoid valve to drain away the rainwater inside the measuring tube. A disadvantage of this rain gauge is that after that the rainwater inside the measuring tube of the rain gauge is drained away, the conductivity sensors will remain wet for a few minutes and as a result the rain gauge will suffer from a considerable error until all conductivity sensors get dry. The other disadvantage of the rain gauge is that during the time when the rainwater is drained away, the rainfall will be calculated based on the average rainfall rate. This method will fail in cases where the rainfall rate changes rapidly due to wind.

Considering the disadvantages of the abovementioned patented rain gauges, there is a need for an accurate and robust rain gauge with an electrical output signal which does not require excessive maintenance and is not influenced by weather conditions such as temperature or wind or by external causes such as dust, dew, leaf, feather, snowflakes, and hailstones.

OBJECTS OF THE INVENTION

The primary object of this invention is to provide an automatic rainfall measurement system in order to measure rainfall with a high accuracy.

Another object of this invention is to provide an automatic rainfall measurement system whose accuracy is not affected by ambient conditions such as temperature or humidity.

A further object of this invention is to provide an automatic rainfall measurement system whose accuracy is not influenced by external objects such as dust, dew, leaf, feather etc.

Another object of this invention is to provide an automatic rainfall measurement system which recognizes raindrops from snowflakes and hailstones and does not collect snow or hail.

A further object of this invention is to provide an automatic rainfall measurement system whose accuracy is not affected by the size or speed of raindrops or by rain intensity.

Another object of this invention is to provide an automatic rainfall measurement system which automatically drains away the rainwater inside the container of the rain gauge.

A further object of this invention is to provide an automatic rainfall measurement system which can be linked to other electronic devices or systems such as automatic irrigation systems or remote weather monitoring systems.

Another object of this invention is to provide an automatic rainfall measurement system with the abovementioned capabilities which is simple and economical at the same time.

A further object of this invention is to provide an automatic rainfall measurement system which is durable and can operate with a high accuracy for a long time.

SUMMARY OF THE INVENTION

Disclosed is an automatic rainfall measurement system with a set of DC control circuitry which is able to measure the height of rainwater or any other conductive liquid with a high accuracy. The present invention comprises a container with a plurality of conductors and electrodes, a rain collector, a set of DC control circuitry, a rain detector, an electromechanical system to rotate the container of the rain gauge, and a base. The conductors are attached to the wall of the container in columns so that the height of each conductor from the next lower conductor is equal to a constant predetermined value. All conductors are connected to a summing amplifier. The electrodes are attached to the wall of the container in such a way that all electrodes are positioned at equal distances from their adjacent columns of conductors. All electrodes are connected to a DC electric power source. When a volume of rainwater is collected inside the container, the conductors which are touched by rainwater receive equal voltages from the electrodes through rainwater. The voltages received by the conductors are added to one another by the summing amplifier. In order to avoid generating high voltages, which can't be measured by microprocessors, the resulting amount is multiplied by a fraction. At the same time the voltage received by the lowest conductor is measured by a microprocessor. Since all columns of conductors are positioned at equal distances from their adjacent electrodes, the voltages received by all conductors will be equal. Hence the voltage received by the lowest conductor is equal to the voltages received by other conductors. Since the output voltage of the summing amplifier is a negative value, an inverting amplifier is used to convert the output voltage of the summing amplifier to its equivalent positive value. The microprocessor divides the output voltage of the inverting amplifier by the voltage measured from the lowest conductor and multiplies the result by the inverse of the previously mentioned fraction. The result will be equal to the number of conductors which are touched by the rainwater, and since the offset of each conductor from the next lower conductor is equal to a constant predetermined value, the microprocessor can easily calculate the height of rainwater through multiplying the number of the conductors which are in touch with rainwater by the constant offset between two successive conductors.

The rain gauge is initially positioned in such a way that the collector of the rain gauge is inclined toward the ground. Consequently, external objects such as dust, leaf, feather, etc won't enter the container of the rain gauge and won't block the opening of the collector. Thus, filters, which are used to prevent external objects from entering the container of rain gauges, are not needed for the present invention. The rain detector of the system has been designed in such a way that it is not responsive to snowflakes or hailstones. Consequently, the system won't be activated when the rain detector is subjected to snowflakes or hailstones. When it starts raining, the rain detector sends an electrical signal to the control circuitry of the rain gauge. Then the control circuitry activates the electromechanical system in order to rotate the rain gauge to its vertical position. Hence, the rain gauge will be able to collect raindrops and measure the height of rainwater at the same time. If the height of the rainwater inside the container does not increase for a certain period of time, it means that it has stopped raining. In this case, the rain gauge measures the final height of rainwater, and the microprocessor inversely activates the electromechanical system to rotate the container of the rain gauge back to its initial downward facing position with its collector toward the ground. Hence, the rainwater inside the container of the rain gauge is drained away by the gravity force.

In the present invention, the electronic circuitry which measures rainfall does not depend on the electromechanical system, which rotates the container of the rain gauge. As a result, mechanical malfunctions caused by temperature fluctuations, fatigue or the presence of dust on the pivots or joints will not affect the accuracy of the rain gauge. Besides, since external objects such as dust, leaf, feather, etc can neither enter the container of the rain gauge nor block the opening of the collector of the rain gauge, the accuracy of the rain gauge is not influenced by external objects. Since the electronic measurement system of the present invention directly measures the height of rainwater, its accuracy is not affected by the size or speed of raindrops or intensity of rain or density of rainwater. The DC control circuitry of the present invention, which will be explained in details, is much simpler than the control circuitry of similar rain gauges. Finally, since the rain detector of the system is not responsive to snowflakes or hailstones, the container of the rain gauge of the system won't collect snow or hail.

DETAILED DESCRIPTION OF THE INVENTION

The first embodiment of the present invention10, which has been illustrated inFIG. 1andFIG. 2, comprises a rain gauge50, a rain detector360a base420, and a motor housing220, which includes an electric motor310with a gearbox330, an encoder320, and part of the control circuitry430. The rain gauge50of the first embodiment of the system10, which will be described in details, is attached to the motor shaft340through a shaft mount80, which is fixed to the bottom140of the rain gauge50. The motor housing220and the rain detector360can be permanently or temporarily fixed to the base420through support rods240and410. That is, the support rods240and410may be screwed or welded to the base420or they may be a permanent part of the base420.

The rain gauge50of the first embodiment of the system10, which has been shown inFIG. 3andFIG. 4, comprises a container60with a shaft mount80, a collector170, and a circuit housing70with a lid90. The circuit housing70includes part of the electronic circuitry430of the first embodiment of the system10. The shaft mount80and the circuit housing70may be attached to the container60or may be a permanent part of the container60. The lid90of the circuit housing70can be attached to the circuit housing70through screws120and screw holes110or by other means and methods. An opening100has been provided on the lid90so that the wires which connect the circuit of the rain gauge50to the other parts of the control circuitry430can pass through the opening100. The collector170is preferred to be attached to the container60temporarily so that it can be removed for the purpose of diagnosis. The container60of the rain gauge50shown inFIG. 3,FIG. 4, andFIG. 5is cylindrical with a side wall130and a bottom140, but it may be in any other suitable shape such as cubic. The container60, circuit housing70, and the shaft mount80are preferred to be made of hard plastic to be as light as possible, but they can be made of any other suitable nonconductive material.FIG. 5illustrates the inside of the container60of the rain gauge50. A plurality of electrodes150together with a plurality of conductors160are attached to the side wall130of the container60. A thin shield135is placed between the area where raindrops fall and the electrodes150and conductors160to prevent falling raindrops from bouncing on the conductors160. The shield135can be a permanent part of the container60and should be as thin as possible so that it does not occupy a considerable volume of the container60. Note that for highly accurate measurement of rainfall, the base area of the empty cylindrical space of the container60should be considered as the area of the bottom140of the container60minus the common area between the shield135and the bottom140.FIG. 6shows a front view of the electrodes150and conductors160, which are attached to the side wall130of the container60. AlthoughFIG. 6illustrates two electrodes150and three columns of conductors160, more electrodes150and columns of conductors160may be used if necessary. In the shown pattern, each electrode150lies between two columns of conductors160so that the columns of conductors160are at equal distances from their neighboring electrodes150. This is important because rainwater has some electrical resistivity. Consequently, there will be some voltage drop due to the resistivity of rainwater. That is why, the columns of conductors160should be at equal distances from their neighboring electrodes150so that all conductors160receive the same voltage.FIG. 7, which is a front view of a few of the conductors160, shows a possible placement pattern of the conductors160in three columns. The two electrodes150which should lie between the columns of conductors160have not been shown inFIG. 7to avoid making the figure messy. As it is observed fromFIG. 7, each conductor160has some predetermined offset from its neighboring conductors160. In this three-column pattern, each conductor160has an offset of 3d from its neighboring conductor160in the same column. Where d is a predetermined constant value. Besides, in the three-column pattern illustrated inFIG. 7, each conductor160has an offset of d from its immediate upper conductor160in the left column and an offset of 2d from its immediate upper conductor160in the right column. Consequently, in the shown pattern, as the rainwater level rises, the rainwater touches conductors C1to C9successively. Although, it is possible to locate all conductors160in a single column, it is recommended to use patterns with as many columns of conductors as possible to increase the distance between two neighboring conductors160in each column so that when the rainwater inside the container60is drained away, rainwater drops are not stuck between the conductors160. Besides, the more columns of conductors160are, the more the number of conductors160can be. As a result, the predetermined offset d can be chosen to be as small as possible, and consequently the accuracy of the rain gauge can be increased. It should be mentioned that the electrodes150and the conductors160should be placed into the side wall130of the container60in such a way that they do not occupy a considerable volume of the container60, which is used for collecting rainwater, otherwise there will be some error in the measurement of rainwater height due to the volume occupied by electrodes150and conductors160. However, if the electrodes150and conductors160are small in size, the mentioned error will be small. The electrodes150and conductors160may be made of any conductive material such as various metals, but it is recommended to make them of carbon rods. The reason behind this recommendation is that, since the circuit430of the rain gauge50is a DC circuit, the electrodes150and conductors160which are made of any sort of metal, will be corroded very fast due to electrolysis. Another noteworthy issue is that the offset d, which is shown inFIG. 7, is a crucial parameter for the accuracy of the rain gauge50. In fact, assuming that the manufacturing error of the various components of the rain gauge50and the error of the control circuitry430are equal to zero, the maximum error of the rain gauge50will be equal to d(D1/D2)2. Where, d is the offset shown inFIG. 7, D1is the diameter of the base area of the empty space of the container60, and O2is the upper diameter of the collector170. The method to calculate the maximum error of the rain gauge50will be explained in details in the following paragraph.

The collector170of the rain gauge50is illustrated inFIG. 8. The collector170shown inFIG. 8is a funnel-like water catchment180with an inclined bottom190and a tube200. There is an opening210at the lowest part of the inclined bottom190through which rainwater flows into the container60of the rain gauge50. In fact, the inclined bottom190of the collector170prevents raindrops from falling on the conductors160and directs them toward the opening210, which lies at a position away from the conductors160. The diameter of the tube200is slightly greater than the diameter of the container60so that when the mouth of the container60is pushed into the tube200of the collector170, the collector170tightly attaches to the container60. The collector170is preferred to be made of hard plastic to be light and corrosion-resistant, but it can be made of other suitable materials. The upper diameter of the collector170plays a key role in adjusting the accuracy of the rain gauge50. The maximum error of the rain gauge50can be calculated as follows: Let D1be the diameter of the base area of the empty space of the container60. Note that the base area of the empty space of the container60is equal to the bottom area of the container60minus the common area between the shield135and the bottom140. In other words, assuming that D is the internal diameter of the container60and A is the cross-sectional area of the shield135, then the diameter of the base area of the empty space of the container60is calculated as follows:

Let D2be the upper diameter of the collector170, and h be the height of the rainwater inside the container. As it is observed fromFIG. 7, if the level of rainwater lies somewhere between k'th conductor and (k+1)'th conductor, then the measured height of the rainwater inside the container60will be either hm=kd or hm=(k+1)d. In other words, the maximum measurement error in the height of the rainwater inside the container60of the rain gauge50will be equal to d. Thus, the maximum error of the measured volume of rainwater will be pi(D1/2)2d. This volume of water, in an imaginary cylindrical container with the same diameter as the upper diameter of the collector170, will be equal to pi(D2/2)2He. Where, Heis the height of the rainwater inside the imaginary cylindrical container. Thus, pi(D1/2)2d=pi(D2/2)2He, which results in He=d(D1/D2)2. Therefore, the maximum error of the rain gauge50will be equal to d(D1/D2)2.

The motor housing220illustrated inFIG. 9andFIG. 10comprises a box230, a support rod240, and a lid250. The box230of the motor housing220includes part of the electronic circuitry430, which is not shown inFIG. 9andFIG. 10, an electric motor310with a gearbox330, a shaft340, and an encoder320. The box230of the motor housing220shown inFIG. 10has been designed to protect its contents from rain and other possible damaging causes. However, the motor housing220may be in other suitable shapes such as cylindrical. The electric motor310can be attached to the box230of the motor housing220through a plurality of screws300and screw holes290and350or by other suitable fasteners and methods. A shaft hole280on the front face of the box230allows the shaft340of the electric motor310to come out of the box230so that it can be fastened to the shaft mount80of the rain gauge50. The lid250of the motor housing220can be attached to the box230through a plurality of screws270and screw holes260or other fasteners or methods. An opening255has been provided on the lid250so that wires which connect the circuit inside the motor housing220to the rain sensors370and to the circuit of the rain gauge50can pass through the opening255. The support rod240of the motor housing220may be screwed into the box230or it can be fixed to the box230by other fasteners and methods. The motor housing220can be made of aluminum to be light and corrosion-resistant. However, it can be made of other proper materials such as hard plastic.

The rain detector360, which has been illustrated inFIG. 11andFIG. 12, includes two rain sensors370, a sensor support400, and a support rod410. The rain sensors370can be attached to the sensor support400through a plurality of screws380and screw holes390or by other fasteners and methods. The sensor support400shown inFIG. 11andFIG. 12is a triangular prism, but it may be in any other suitable shape such as pyramid, conical, etc. The side surfaces of the sensor support400should have a slope of at least 45 degrees so that the raindrops which fall on the rain sensors370do not remain on the rain sensors370and roll off downward. The support rod410of the rain detector360can be screwed into the sensor support400or can be fixed to the sensor support400by other fasteners or methods. The sensor support400and the support rod410can be made of aluminum or any other suitable material which is light and corrosion-resistant such as hard plastic. It should be mentioned that the rain detector360described here may be replaced by other sorts of rain detectors, which have been invented so far or will be invented in future.

The rain sensor370, which has been illustrated inFIG. 13, is simply a printed circuit375with no electrical components. The horizontal tracks of the circuit are parallel to one another, and each horizontal track is separated from its neighboring horizontal track by a small distance of about 1 mm to 2 mm. In each pair of neighboring parallel tracks, one track is connected to the input terminal of the circuit375through a vertical track, and the other one is connected to the output terminal through another vertical track. Hence, when a raindrop falls on the circuit375of the rain sensor370, the pair of neighboring parallel tracks which have been subjected to the raindrop are connected to each other by the raindrop and thus, electric current flows from the input terminal to the output terminal of the circuit375of the rain sensor370. Finally, the current flow is transferred to a microprocessor as an electrical signal. Note that when the rain sensor370is subjected to snowflakes or hailstones, no signal will be sent by the rain sensor370simply because of very low conductivity of snowflakes and hailstones.

The base420of the first embodiment of the system10has been chosen to be a rectangular plate with a certain thickness. However, it may be in any other suitable shape such as a circular or elliptic disc. The base420can be made of aluminum to be corrosion-resistant and light or it can be made of any other suitable material such as hard plastic.

The control circuitry430of the first embodiment of the system10has been illustrated inFIG. 14. The control circuitry430of the first embodiment of the system10comprises a DC voltage source, a plurality of electrodes150designated by E1to Em, rainwater, a plurality of conductors160designated by C1to Cn, a summing amplifier, an inverting amplifier, a rain detector360, a microprocessor, a motor driver, an electric motor310, an encoder320, and an LCD. As it is observed fromFIG. 14, the electrodes E1to Em are connected to the voltage source of the circuitry430. As the level of rainwater rises inside the container60of the rain gauge50, the rainwater successively connects the conductors C1to Cn to the electrodes E1to Em. Consequently, among the conductors C1to Cn those which are touched by rainwater receive equal voltages from the electrodes E1to Em and transfer the voltages to the summing amplifier through wires as shown inFIG. 15. The summing amplifier shown inFIG. 15consists of a plurality of input resistors R with equal resistances, an OPAMP OP1, and a feedback resistor r. The output voltage of the summing amplifier is received by an inverting amplifier, which has been shown inFIG. 15. The inverting amplifier includes an input resistor r, a feedback resistor r, and an OPAMP OP2. Assume that VSUis the output voltage of the summing amplifier, VCis the voltage of the lowest conductor C1, VIis the output voltage of the inverting amplifier, k is the number of the conductors C1to Ck touched by the rainwater, d is the offset between two successive conductors Ci and C(i+1), R is the resistance of the input resistors of the summing amplifier, r is the feedback resistance of the summing amplifier, h is the height of the rainwater inside the container60, H is rainfall, which is measured in depth, D1is the diameter of the base area of the empty space of the container60, and D2is the upper diameter of the collector170. The output voltage of the summing amplifier is determined from VSU=−k(r/R)VC. In order to avoid generating high voltages, which cannot be measured by microprocessors, the magnitudes of r and R should be chosen in such a way that VSUdoes not exceed 5 volts. For example if there are 200 conductors160in the rain gauge50, and VC=10 volts, then r/R can be chosen to be equal to 1/400. Thus the maximum output voltage of the summing amplifier will be −5 volts. Since the resistance of the input resistor r of the inverting amplifier is equal to the resistance of its feedback resistor r, the gain of the inverting amplifier is equal to unity. Hence the output voltage of the inverting amplifier can be determined from VI=−VSU=k(r/R)VC. As it is observed fromFIG. 14, the microprocessor receives the output voltage of the inverting amplifier, VI, and the voltage of the lowest conductor C1, VC, which is equal to the voltage of the conductors C1to Ck, which are in touch with rainwater. Then the microprocessor makes the following calculations: k=(RV1)/(rVC), h=dk, and H=(D2/D1)2h.

Thus, the microprocessor determines rainfall, H. It should be mentioned that the wires which connect the electrodes150and the conductors160to the summing amplifier together with the summing and inverting amplifiers lie inside the circuit housing70while, the voltage source, the microprocessor, the motor driver, the electric motor310, and the encoder320lie inside the box230of the motor housing220. The operation of the control circuitry430is explained in details in the next paragraph.

FIG. 16andFIG. 17illustrate an algorithm which can be used by the microprocessor to run the first embodiment of the system10. When it starts raining, using this algorithm, the microprocessor communicates with the motor driver and the encoder320to vertically position the rain gauge50, interrupts an automatic irrigation system, which is connected to the first embodiment of the system10, measures rainfall by the previously mentioned method, and displays rainfall, which has been measured in depth, on an LCD. After that it stops raining, the microprocessor informs the automatic irrigation system of rainfall, reactivates the automatic irrigation system and returns the rain gauge50back to its initial downward facing position. Assume that VSis the voltage received from the rain detector360by the microprocessor, t is the measured time, θ is the angular position of the motor shaft340, H1is the rainfall calculated according to the former voltage measurements, and H2is the rainfall calculated according to the current voltage measurements. In step S10of the algorithm, the values of VS, VC, VI, t, θ, and H1are set equal to zero. In step S20, the voltage received from the rain detector360is measured. In step S30, it is decided if the voltage received from the rain detector360is greater than zero or not. If the voltage received from the rain detector360is not greater than zero, it means that it is not raining. In this case, the microprocessor keeps measuring the voltage received from the rain detector360and comparing its value with zero. But if the voltage received from the rain detector360is greater than zero, then the microprocessor goes to step S40of the algorithm and starts measuring the time. In step S50, the electric motor310is activated through the motor driver. As the motor shaft340starts rotating, the angular position of the motor shaft340is measured through the encoder320in step S60. Then in step S70of the algorithm shown inFIG. 16andFIG. 17, it is decided if the angular position of the motor shaft340is equal to the desired value, which has been chosen to be 120 degrees in this case. In other words, in the algorithm shown inFIG. 16andFIG. 17, it has been assumed that the rain gauge50was initially inclined downward by an angle of 120 degrees from its vertical position. The angular position of the motor shaft340is continuously measured by the encoder320until it reaches 120 degrees. When the angular position of the motor shaft340reaches 120 degrees, the rain gauge50will be in its vertical position. In this case the motor driver brakes and stops the motor310in Step S80. Then in step S90, the voltage of the lowest conductor C1is measured. In step S100the microprocessor decides if the voltage of the lowest conductor C1is greater than zero or not. If the voltage of the lowest conductor C1remains equal to zero for a certain period of time, which is two hours in this case, then it means that it is not raining, and the signal sent by the rain detector360was the result of an accidental water spill on the rain sensors370. But if the voltage of the lowest conductor C1becomes greater than zero within the two hours, then it means that it is raining, and some water has been collected by the container60of the rain gauge50. In step S110, the microprocessor decides if the time during which the voltage of the lowest conductor C1has remained equal to zero is greater than two hours or not. If the voltage of the lowest conductor C1remains equal to zero for two hours, the electric motor310is inversely activated by the motor driver in step S120. That is, the electric motor310starts rotating the rain gauge50back to its initial downward facing position shown inFIG. 2. In step S130, the angular position of the motor shaft340is measured by the encoder320then in step S140, the microprocessor decides if the angular position of the motor shaft340is equal to zero or not. If the angular position of the motor shaft340is equal to zero, it means that the rain gauge50is back to its initial downward facing position. In this case, the motor driver brakes the electric motor310and then deactivates it in step S150. Otherwise, the microprocessor keeps the electric motor310running until the angular position of the motor shaft340becomes equal to zero. After that the rain gauge50is back to its initial position, the microprocessor returns to step S10and restarts applying the algorithm shown inFIG. 16andFIG. 17. If in step S100it is decided that the voltage of the lowest conductor C1, which was measured in step S90, is greater than zero, the microprocessor goes to step S160and interrupts the automatic irrigation system, which is connected to the first embodiment of the system10. Then the voltage of the lowest conductor C1is measured once again together with the output voltage of the inverting amplifier in step S170. The point behind the remeasurement of the voltage of the lowest conductor C1is that the voltage of the lowest conductor C1may slightly change due to noise or other reasons over time, and since the output voltage of the inverting amplifier is a function of the voltage of the lowest conductor C1, any changes in the voltage of the lowest conductor C1will lead to variations in the output voltage of the inverting amplifier. In other words, in order to make sure that both the voltage of the lowest conductor C1and the output voltage of the inverting amplifier are measured under identical conditions and are correlated to each other according to equation V1=−VSU=k(r/R)VC, they should be measured simultaneously. In step S180, the number of the conductors which are in touch with the rainwater is determined from equation k=(RVI)/(rVC). Then the microprocessor determines the height of the rainwater inside the container60of the rain gauge50from h=dk in step S190. In step S200, the current rainfall is calculated from H2=(D2/D1)2h. Then the current rainfall is compared with the former rainfall in step S210. If the current rainfall, H2, is not greater than the previous one, H1, the microprocessor goes to step S220to decide if the time measured since the last increase in rainfall is greater than a certain period, which is two hours in this case, or not. If the time measured since the last increase in the rainfall is greater than two hours, then it means that it has stopped raining. In this case, the automatic irrigation system is informed of the final rainfall in step S230and then the automatic irrigation system is activated by the microprocessor in step S240. Then the microprocessor goes to step S120and starts the previously described process to rotate the rain gauge50back to its initial downward facing position. When the rain gauge50is back to its initial downward facing position, the rainwater inside the rain gauge50is drained away by gravitational force through the opening210on the bottom190of the collector170. In step S220, if the time measured since the last increase in rainfall is less than the threshold period of time, which has been chosen to be two hours in this case, the microprocessor goes back to step S170to update the current rainfall through steps S170to S200and then compares the updated value of the current rainfall with the previous one in step S210. In step S210if the current rainfall, H2, is greater than the previous one, H1, it means that it keeps raining. In this case the microprocessor goes to step S250to display the current rainfall on the LCD. Then it restarts measuring the time in step S260. In step S270the value of the former rainfall, H1, is replaced by the value of the current rainfall, H2. Then microprocessor goes to step S170to update the current rainfall through steps S170to S200.

In order to operate the first embodiment of the system10, the rain gauge50should initially lie in its downward facing position as shown inFIG. 2. When the rain gauge50is inclined downward, the opening210on the bottom190of the collector170won't be blocked by external objects such as leaf, feather, dust, etc and external objects won't enter the container60of the rain gauge50. As soon as a raindrop falls on a rain sensor370of the rain detector360, the rain detector360sends an electrical signal to the microprocessor. Then the microprocessor activates the electric motor310and consequently, the electric motor310rotates the rain gauge50through the gearbox330and the shaft340. Obviously, the gearbox330is used in order to reduce the speed of the shaft340and to increase its torque. The microprocessor frequently measures the angular position of the shaft340through the encoder320. When the rain gauge50reaches its vertical position shown inFIG. 1, the microprocessor brakes the electric motor310through the motor driver and then deactivates it. Now the rain gauge50is ready to collect rainwater and measure the height of rainwater through the previously mentioned method. As soon as the lowest conductor C1of the rain gauge50is touched by rainwater, the microprocessor interrupts the automatic irrigation system which is connected to the first embodiment of the system10and starts displaying rainfall on an LCD. According to the algorithm shown inFIG. 16, if the height of rainwater inside the container60of the rain gauge50does not increase for a certain period of time, which is two hours in this case, the microprocessor will inform the automatic irrigation system of rainfall and will reactivate it. Then the microprocessor will inversely activate the electric motor310through the motor driver until the rain gauge50is rotated back to its downward facing position shown inFIG. 2so that the gravitational force drains away the rainwater inside the container60through the opening210on the bottom190of the collector170.

It should be mentioned that it is possible to precisely position the rain gauge50by means of a step motor together with a zero-backlash gearbox without using an encoder. However, if the gearbox has some backlash, then it will be necessary to use an encoder in order to precisely position the rain gauge50.

Another noteworthy issue is that after that the rainwater inside the container60of the rain gauge50is drained away, the conductors C1to Ck which were in touch with the rainwater will remain wet for a few minutes. As a result, the rain gauge50will suffer from a considerable amount of error until all conductors C1to Ck get dry. That is why the first embodiment of the system10is suitable for measuring rainfall in regions where the rainfall produced by, each continuous raining is less than about 20 cm.

The second embodiment of the system510, which has been illustrated inFIG. 18,FIG. 19andFIG. 20, comprises two rain gauges550and560, a motor housing720, a rain detector860and a base920. The rain gauges550and560of the second embodiment of the system510are attached to the motor shafts840and850through shaft mounts580and590, which are fixed to the bottoms of the rain gauges550and560. The motor housing720and the rain detector860can be permanently or temporarily fixed to the base920through support rods740and910. That is, the support rods740and910may be screwed or welded to the base920or they may be a permanent part of the base920.

The structure of the rain gauges550and560of the second embodiment of the system510is almost identical to that of the rain, gauge50of the first embodiment of the system10, with only two differences. The collector670of the rain, gauges550and560, which has been illustrated inFIG. 21, comprises one more opening715on the highest part of its inclined bottom690. This additional opening715is useful to drain away the rainwater inside the container of the rain gauges550and560. That is, when the rain gauges550and560are in their downward facing positions, which have been illustrated inFIG. 8,FIG. 19, andFIG. 20the rainwater inside the containers of rain gauges550and560can be drained away from either of the openings715or710. Similar to the opening710which lies on the lowest part of the inclined bottom690of the collector670, the additional opening715on the highest part of the inclined bottom690lies in a position away from the conductors so that the raindrops which pass through the additional opening715won't fall on the conductors. The second difference between the rain gauges550and560of the second embodiment of the system510and the rain gauge50of the first embodiment of the system10is that the containers of the rain gauges550and560of the second embodiment of the system510include one more shield which is located between the area where raindrops fall through the additional opening715and the conductors. Similar to the shield135of the rain gauge50of the first embodiment of the system10, the additional shield should be as thin as possible so that it does not occupy a considerable volume of the rain gauges550and560. Similarly, assuming that the manufacturing error of the various components of the rain gauges550and560and the error of the control circuitry930are equal to zero, the maximum error of the rain gauges550and560will be the same as the maximum error of the rain gauge50of the first embodiment of the system10which is equal to d(D1/D2)2, where d, D1, and D2were previously explained when determining the maximum error of the rain gauge50of the first embodiment of the system10.

The motor housing720illustrated inFIG. 22,FIG. 23, andFIG. 24comprises a box830, a support rod740, and a lid750. The box830of the motor housing720includes part of the electronic circuitry930, which is not shown inFIG. 22,FIG. 23, andFIG. 24, an electric motor810with a dual gearbox845, two shafts840and850, and an encoder820. The box830of the motor housing720shown inFIG. 22,FIG. 23andFIG. 24has been designed to protect its contents from rain and other possible damaging causes. However, the motor housing720may be in other suitable shapes such as cylindrical. The electric motor810can be attached to the box830of the motor housing720through a plurality of screws805and800and screw holes795,855,815, and862or by other suitable fasteners and methods. Two shaft holes785and825on the side faces of the box830allow the shafts840and850of the electric motor810to come out of the box830so that they can be fastened to the shaft mounts580and590of the rain gauges550and590. The lid750of the motor housing720can be attached to the box830through a plurality of screws775and screw holes765and838or other fasteners or methods. An opening760has been provided on the rear face of the box830so that wires which connect the rain detector860and the circuits of the rain gauges550and560to the circuit inside the box830of the motor housing720can pass through the opening760. The support rod740of the motor housing720may be screwed into the box830or it can be fixed to the box830by other fasteners and methods. The motor housing720can be made of aluminum to be light and corrosion-resistant or it can be made of other suitable materials such as hard plastic. The gear ratios of the dual gearbox845are equal so that both shafts840and850rotate with the same angular speeds and angular accelerations.

The rain detector860of the second embodiment of the system510is identical to the rain detector360of the first embodiment of the system10, which was explained in details.

The base920of the second embodiment of the system510is the same as the base420of the first embodiment of the system10which was previously described.

The control circuitry930of the second embodiment of the system510has been illustrated inFIG. 25. The control circuitry930of the second embodiment of the system510comprises DC voltage sources, the plurality of electrodes of the first rain gauge550designated by E1to E′m, the plurality of electrodes of the second rain gauge560designated by E″1to E″m, the plurality of conductors of the first rain gauge550designated by C′1to C′n, the plurality of conductors of the second rain gauge560designated by C″1to C″n, the rainwater inside the first rain gauge550, the rainwater inside the second rain gauge560, the summing amplifier of the first rain gauge550, the summing amplifier of the second rain gauge560, the inverting amplifier of the first rain gauge550, the inverting amplifier of the second rain gauge560, a rain detector860, a microprocessor, a motor driver, an electric motor810, an encoder820, and an LCD. As it is observed fromFIG. 25, the electrodes E′1to E′m and E″1to E″m are connected to a DC voltage source. As the level of rainwater rises inside the container of the vertically positioned rain gauge550or560, rainwater successively connects the conductors C′1to C′n or C″1to C″n of the vertically positioned rain gauge550or560to the electrodes E′1to E′m or E″1to E″m of the vertically positioned rain gauge550or560. Consequently, among the conductors C′1to C′n or C″1to C″n of the vertically positioned rain gauge550or560, those which are touched by rainwater receive equal voltages from the electrodes E′1to E′m or E″1to E″m and transfer the voltages to the summing amplifier of the vertically positioned rain gauge550or560through wires as shown inFIG. 15. The summing amplifiers and the inverting amplifiers of the first and second rain gauges550and560are identical to the summing amplifier and the inverting amplifier of the rain gauge50of the first embodiment of the system10, which were previously explained in details. The method which is used by the microprocessor to determine water level in the containers of the first and second rain gauges550and560is the same as the method used by the microprocessor of the first embodiment of the system10and was explained in details when describing the control circuitry430of the first embodiment of the system10. However, the operation of the control circuitry930of the second embodiment of the system510, which will be explained in details in the next paragraph, is slightly different from the operation of the control circuitry430of the first embodiment of the system10.

FIG. 26andFIG. 27illustrate an algorithm which can be used by the microprocessor to run the second embodiment of the system510. Using this algorithm, the microprocessor interrupts an automatic irrigation system, which is connected to the second embodiment of the system510, measures rainfall, displays rainfall, which is measured in depth, on an LCD, informs the automatic irrigation system of rainfall and communicates with the motor driver and the encoder820to precisely position the rain gauges550and560. In the algorithm shown inFIGS. 26 and 27, it has been assumed that the rain gauges550and560are apart from each other by an angle of 120 degrees and both are initially inclined downward so that the first rain gauge550is inclined from its vertical position by an angle of 120 degrees (FIG. 18). However, the angle between the two rain gauges550and560may be chosen to be any other suitable angle. Note that most of the equations and formulas which have been used in the algorithm shown inFIG. 26andFIG. 27were previously explained in details when describing the control circuitry430of the first embodiment of the system10. That is why only new equations of the algorithm shown inFIG. 26andFIG. 27, which were not used in the algorithm shown inFIG. 16andFIG. 17, will be explained here. Assume that VC′1is the voltage of the lowest conductor C′1of the first rain gauge550, VC″1is the voltage of the lowest conductor C″1of the second rain gauge560, VI′is the output voltage of the inverting amplifier of the first rain gauge550, VI″is the output voltage of the inverting amplifier of the second rain gauge560,0is the angular position of the first shaft840(note that since the gear ratios for both shafts840and850are equal, their angular speeds will be equal too.), C is the counter, and Hmaxis the maximum height of the rainwater which can be measured by each of the rain gauges550and560. Other parameters and variables used in the algorithm illustrated inFIG. 26andFIG. 27are the same as the parameters and variables which were used in the algorithm which was previously presented to run the first embodiment of the system10and were previously defined. In step S300of the algorithm, shown inFIG. 26, the values of VS, VC′1, VC″1, VI′, VI″, C, t, θ, and H1are set equal to zero. In step S310, the voltage received from the rain detector860is measured. In step S320, it is decided if the voltage received from the rain detector860is greater than zero or not. If the voltage received from the rain detector860is not greater than zero, it means that it is not raining. In this case, the microprocessor keeps measuring the voltage received from the rain detector860and comparing its value with zero. But if the voltage received from the rain detector860is greater than zero, then the microprocessor goes to step S330of the algorithm and starts measuring the time. In step S340, the electric motor810is activated through the motor driver. As the shafts840and850start rotating, the angular position of the first shaft840is measured through the encoder820in step S350. Then in step S360of the algorithm shown inFIG. 26, it is decided if the angular position of the first shaft840is equal to the desired value, which has been chosen to be 120 degrees in this case. When the angular position of the first shaft840reaches 120 degrees, the first rain gauge550will be in its vertical position and the second rain gauge560will be inclined downward by an angle of 120 degrees from the first rain gauge550(FIG. 19). In this case, the motor driver brakes and stops the motor810in Step S370. Then in step S380, the microprocessor decides if the value of the counter is odd or even. If the value of the counter is an even number, it means that the first rain gauge550lies in its vertical position collecting and measuring rainfall, and the second rain gauge560lies in its downward facing position (FIG. 19). But if the value of the counter is an odd number, it means that the second rain gauge560is in its vertical position collecting and measuring rainfall, and the first rain gauge550lies in its second downward facing position (FIG. 20). Once that the microprocessor recognizes the rain gauge550or560which lies in the vertical position, it measures the voltage of the lowest conductor C′1or C″1of the vertical rain gauge550or560in step S390or S400. The measured value of the voltage received from the lowest conductor C′1or C″1is assigned to VCin step S410or S420. Then it is decided if the value of VCis greater than zero or not. If the value of VCis not greater than zero, the microprocessor checks the measured time in step S440. If the measured time is less than two hours, the microprocessor returns to step S380and keeps measuring the voltage of the lowest conductor C′1or C″1of the vertical rain gauge550or560and comparing it with zero. But if the measured time is greater than two hours, that is, if the voltage of the lowest conductor C′1or C″1remains equal to zero for two hours, it means that it is not raining and the electrical signal sent by the rain detector860was the result of an accidental water spill on the rain sensors. In this case, the microprocessor goes to step S450and inversely activates the electric motor810. As a result, the rain gauges550and560are rotated back to their initial downward facing positions shown inFIG. 18. The angular position of the first shaft840is continuously measured by an encoder820and is compared with zero by the microprocessor in steps S460and S470. When the angular position of the first shaft840becomes equal to zero, the rain gauges550and560will be in their initial downward facing positions shown inFIG. 18. In this case, the microprocessor brakes and then deactivates the electric motor810through the motor driver. Then the microprocessor goes back to step S300and restarts applying the algorithm shown inFIG. 26andFIG. 27. If in step S430the microprocessor decides that the value of VCis greater than zero, then it means that it is raining and some rainwater has been collected by the container of the vertical rain gauge550or560. In this case, the microprocessor goes to step S490and interrupts the automatic irrigation system. Then in step S500, the value of the counter is checked. If the value of the counter is an even number, it means that the first rain gauge550is in its vertical position to collect and measure rainfall (FIG. 19). Consequently, the microprocessor measures the voltage of the lowest conductor C′1of the first rain gauge550and the output voltage of the inverting amplifier of the first rain gauge550in step S520and assigns them to VCand VIrespectively in step S540. But if the value of the counter is an odd number, it means that the second rain gauge560is in its vertical position to collect and measure rainfall (FIG. 20). Consequently, the microprocessor measures the voltage of the lowest conductor C″1of the second rain gauge560and the output voltage of the inverting amplifier of the second rain gauge560in step S510and assigns them to VCand VIrespectively in step S530. Note that although the voltage of the lowest conductor C′1or C″1of the vertical rain gauge550or560was previously measured in step S390or step S400, it is necessary to measure the voltage of the lowest conductor C′1or C″1of the vertical rain gauge550or560once again in step S520or S510. The reason behind updating the voltage of the lowest conductor C′1or C″1of the vertical rain gauge550or560was previously explained when describing step S170of the algorithm shown inFIG. 16andFIG. 17. In step S550, the number of the conductors C′1to C′k or C″1to C″k of the vertical rain gauge550or560which are touched by rainwater is determined through equation k=(RV1)/(rVC). In step S560, the height of the rainwater inside the vertical rain gauge550or560, h, is calculated according to the number of the conductors C′1to C′k or C″1to C″k which are touched by rainwater through equation h=dk, and then the corresponding portion of the current rainfall, H, is calculated in step S570through H=(D2/D1)2h. Finally the current total rainfall, H2, is determined in step S580through H2=H+CHmax. Note that in the present equation, the value of the counter, C, indicates the number of times that the height of rainwater inside rain gauges550and560has reached the maximum capacity of the rain gauges550and560. For example, if C=2, it means that the first and second rain gauges550and560were successively filled up of rainwater and emptied once. In other words, in equation presented in step S580, CHmaxreflects the height of rainwater which has filled up the rain gauges550and560for C times. Then in step S590, it is decided if the currently calculated total rainfall, H2, is greater than the formerly calculated one, H1, or not. If the currently calculated total rainfall is not greater than the formerly calculated one, the microprocessor checks the measured time in step S600to decide if the measured time is greater than two hours or not. If the measured time is not greater than two hours, then the microprocessor returns to step S500and repeats steps S500to S590in order to update the value of H2and compare it with H1. But if the measured time is greater than two hours, it means that there has been no increase in rainfall during the last two hours, which means that it has stopped raining. In this case, the microprocessor goes to step S610and informs the automatic irrigation system of the final value of the total rainfall. Then the microprocessor goes to step S450and performs the previously mentioned operations to rotate the rain gauges550and560back to their initial downward facing positions shown inFIG. 18and restarts the algorithm in step S300. If in step S590, the currently calculated total rainfall, H2, is greater than the formerly calculated total rainfall, H1, then in step S620, the value of the currently calculated rainfall is displayed on the LCD and the microprocessor restarts measuring the time in step S630. In step S640, it is decided if the height of the rainwater inside the container of the vertical rain gauge550or560is equal to the maximum measurable height of rainwater or not. If the height of the rainwater inside the container of the vertical rain gauge550or560is not equal to the maximum measurable height of rainwater, then the value of H2is assigned to H1in step S650, and the microprocessor goes back to step S500to update the value of the current rainfall, H2through steps S500to S590and compare it with H1. But if the height of the rainwater inside the container of the vertical rain gauge550or560is equal to the maximum measurable height of rainwater, then it means that the container of the vertical rain gauge550or560has been filled up with rainwater. In this case, the value of H1is reset equal to zero in step S660, and the value of the counter is increased by unity in step S670. Then in step S680, it is decided if the value of the counter is an odd number or an even number. If the value of the counter is an odd number, it means that the first rain gauge550lies in its vertical position measuring rainfall, and the second rain gauge560is inclined downward (FIG. 19). In this case, the microprocessor activates the electric motor810through the motor driver in step S690and measures the angular position of the first shaft840through the encoder820in step S700. In step S710, it is decided if the angular position of the first shaft840has reached 240 degrees or not. As long as the angular position of the first shaft840has not reached 240 degrees, the microprocessor keeps running the electric motor810and measuring the angular position of the first shaft840through the encoder820. When the angular position of the first shaft840reaches 240 degrees, the second rain gauge560will be in its vertical position measuring rainfall and the first rain gauge550will be inclined downward so that the rainwater inside the first rain gauge550will be drained away through the opening710(FIG. 20). Then, the microprocessor goes back to step S370to measure the rest of rainfall by means of the second rain gauge560. If in step S680it is decided that the value of the counter is an even number, it means that the second rain gauge560lies in its vertical position measuring rainfall and the first rain gauge550is inclined downward (FIG. 20). In this case the microprocessor inversely activates the electric motor810through the motor driver in step S720and measures the angular position of the first shaft840through the encoder820in step S730. In step S740, it is decided if the angular position of the first shaft840is equal to 120 degrees or not. As long as the angular position of the first shaft is not equal to 120 degrees, the microprocessor keeps inversely rotating the electric motor810and measuring the angular position of the first shaft840. When the angular position of the first shaft840becomes equal to 120 degrees, the first rain gauge550will lie in its vertical position measuring rainfall and the second rain gauge560will be inclined downward so that the rainwater inside the second rain gauge560will be drained away through the opening710(FIG. 19). Then, the microprocessor goes back to step S370to measure the rest of rainfall by means of the first rain gauge550.

In order to operate the second embodiment of the system510, the rain gauges550and560should initially lie in their downward facing positions as shown inFIG. 18. When the rain gauges550and560are inclined downward, the openings710and715on the bottom690of the collector670won't be blocked by external objects such as leaf, feather, dust, etc, and external objects won't enter the container of the rain gauges550and560. As soon as a raindrop falls on a rain sensor of the rain detector860, the rain detector860sends an electrical signal to the microprocessor. Then the microprocessor activates the electric motor810and consequently, the electric motor810rotates the rain gauges550and560through the gearbox845and the shafts840and850. Obviously, the gearbox845is used in order to reduce the speed of the shafts840and850and to increase their torques. The microprocessor continuously measures the angular position of the first shaft840through the encoder820. When the first rain gauge550reaches its vertical position shown inFIG. 19, the microprocessor brakes the electric motor810through the motor driver and then deactivates it. Now the first rain gauge550is ready to collect rainwater and measure the height of rainwater through the previously mentioned method. As soon as the lowest conductor C′1of the first rain gauge550is touched by rainwater, the microprocessor interrupts the automatic irrigation system which is connected to the second embodiment of the system510and starts displaying rainfall on an LCD. According to the algorithm shown inFIG. 26andFIG. 27, if the height of rainwater inside the container of the first rain gauge550does not increase for a certain period of time, which is two hours in this case, the microprocessor will inform the automatic irrigation system of the final rainfall and will reactivate it. Then the microprocessor will inversely activate the electric motor810through the motor driver until the first rain gauge550is rotated back to its initial downward facing position shown inFIG. 18so that the gravitational force drains away the rainwater inside the container through the upper opening715on the bottom690of the collector670. If rainfall is so high that the container of the first rain gauge550is filled up with rainwater, then the microprocessor will activate the electric motor810so that the second rain gauge560is rotated to its vertical position and the first rain gauge550is rotated to its second downward facing position (FIG. 20). In this case, the rainwater inside the container of the first rain gauge550is drained away by gravitational force through the lower opening710on the bottom690of the collector670, and the second rain gauge560continues measuring rainfall. As long as it keeps raining, the rain gauges550and560will continue to measure rainfall in turn. In other words, when the container of the vertical rain gauge550or560is filled up with rainwater, the inclined rain gauge550or560will be rotated to its vertical position to measure rainfall and simultaneously the other rain gauge550or560which is filled up with rainwater will be rotated to its downward facing position so that the rainwater inside its container is drained away by gravitational force.

It should be mentioned that it is possible to precisely position the rain gauges550and560by means of a step motor together with a zero-backlash dual gearbox without using an encoder. However, if the dual gearbox has some backlash, then it will be necessary to use an encoder in order to precisely position the rain gauges550and560.

Another noteworthy issue is that the second embodiment of the system510is able to precisely measure all ranges of rainfalls from very high rainfalls to very low rainfalls. However, because of its higher price in comparison to the first embodiment of the system10, it is recommended to be used in regions with high and very high rainfalls.

Although the present invention and its advantages have been described in details, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the design as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments, algorithms, and methods described in the specification. As one of ordinary skill in the art will readily appreciate from the present disclosure that processes, machines, means, methods, and algorithms to be developed later which will perform substantially the same function or will achieve the same results as described through the corresponding embodiments herein, may be utilized according to the present disclosure. Accordingly, the appended claims are intended to include within their scope such processes, machines, means, methods, and algorithms.