GB2290643A - Remote control unit and radio controlled valve - Google Patents

Abstract

A remote terminal unit (10) has a battery source (11), a radio (12) and an antenna (13). The radio, battery source and antenna are mounted on a valve (20) for control thereof, positioned below the uppermost part of the valve and its associated fluid flow elements. The entire unit can be buried in situ adjacent an element (22) of a system to be controlled. <IMAGE>

Description

BURIED REMOTE CONTROL UNIT AND RADIO CONTROLLED VALVE Field of the Invention This invention relates to a buried remote terminal unit, that is to say a unit of a system that supervises or controls another system and that is in communication with a central unit for central control or supervision.

Separately, and in addition, it relates to a radio controlled valve such as for use in an irrigation system.

Background to the Invention Supervisory control and acquisition of data (SCADA) systems, such as Motorola's IRRINET, INTRAC and MOSCAD systems provide remote control of a remote terminal unit (RTU) from a central unit over a radio and/or line link.

The RTU may directly control the system which is being supervised and controlled, for example an irrigation system, by direct connection between the RTU and relay solenoids, sensors and other elements of the system under control. For greater capacity, the RTU can supervise and control the system via one or more terminal units. A number of terminal units can be connect to a single RTU. Each terminal unit can control a number of elements or receive data from a number of elements. In this maner there is a high degree of fan-out between the RTU and the elements being supervised and controlled. Typically the RTUs control solenoids in SCADA irrigating systems. The solenoid operates a tap controlling the closing and opening of the water flow in a pipe, so that irrigation by sprinklers and/or other means can be controlled from a distance.

The RTUs "read" the state of the contacts and/or pulses, and so can check the sensors' state of contacts and measure the amount of water passing through by means of the water meter pulses.

Existing RTUs linked to a solenoid and/or meter are characterized by a number of parameters: placement, casing, communication method, quantity of external parts assembled, and power source. Preferred placements are near a water tap or near a power source (power main or solar cells), compatible to the radio or communications line's requirements and positions giving easy access (e.g. for maintenance). For casing, various sizes of boxes are used. For the communication method, existing systems use two-way radio or receiver only terminal units or use a wire line. Typically the quantity of solenoids and/or linked inputs ranges from one to hundreds. For the power source either electrical mains is used or, in areas without mains supply, a compatible solar battery or a disposable battery.

Irrigation systems in use today in places such as parks, municipal gardens, traffic islands, golf courses, etc., have installed RTUs to operate the system at a distance, either by land lines or by radio, according to the program manually fed to the RTU. In locations where there is a power net, the RTU is placed in a box above ground level, generally in a central location where it can be hooked up to the net, and power lines run from it to control the solenoids (AC). The solenoids are located on the water taps, and are used to control the flow of water in the pipes or on the sprinkler, to control the sprinkler's operation. In places where there is no access to the power net, the RTU is placed in a box above ground level, generally in a central location, and powered by a battery. Most systems charge the battery with solar cells located nearby.

DC solenoids are installed in proximity to the RTU and connected to the RTU's power source. Hydraulic transfer tubes carry the commands from the solenoid to the water controls.

A number of problems can exist in present systems. First systems operating on land lines require linking all RTUs to the line of communication, and these lines increase the cost of installation as well as requiring constant maintenance during the system's operating life (in specific cases, e.g. where a line has to cross a road-up area, the cost of laying such a line can be extremely expensive). A second problem is that the current consumption of the RTU in systems operating through radio communication is high, so in cases where there is no feasible way to link up with the power net, it becomes necessary to install a rechargeable battery and solar cells. A power system of this type considerably increases the cost of the RTU. The solar cell installation must be exposed to the sun, which can, in some instances, cause problems with the RTU placement.Thirdly, RTU installation above ground level can cause various problems, such as landscape pollution (in parks, gardens, etc.), interference with daily operations (on golf courses, parks, gardens, etc.), vulnerability to damages (caused by vandalism or incidental). Fourthly, RTU installation in a central location requires passage of power lines to control the AC solenoids or the hydraulic transfer tubes from the DC solenoids to the taps. Burying control power lines for long distances can considerably increase the cost of system installation, as well as requiring constant maintenance as long as the system is in operation. Burying the hydraulic transfer tubes for great distances can cause blockage problems with them.

There is a need for an improved remote terminal unit.

Summarv of the Invention According to the present invention, a remote terminal unit is provided, having a battery, a radio and an antenna, where the battery, radio and antenna are buried in situ adjacent an element of a system to be controlled or supervised.

The invention has the advantage that the RTU is stand-alone, i.e. it does not require connection to communic8tion lines or power lines. The RTU is buried underground and therefore does not interfere with any other activities in the area and is not vulnerable to damage.

RTU power demands can be kept very low, so it is possible to operate the system for extended periods of time without changing the batteries (1-8 years depending on the type of battery).

According to another aspect of the invention, a radio controlled valve is provided comprising a radio, a battery, an antenna and a fluid control valve with associated fliud flow elements. The radio, battery source and antenna are mounted on the valve for control thereof, positioned below the uppermost part of the valve and its associated fliud flow elements.

A preferred embodiment of the invention is now described, by way of example only, with reference to the drawings.

Brief Description of the Drawings FIG. 1 illustrates the installation of an RTU on a sprinkler in accordance with the preferred embodiment of the invention.

FIG. 2 is a block diagram of the RTU of FIG. 1.

Detailed Description of the Preferred Embodiment The RTU 10 comprises a battery 11, an electronic PCB 12 (which includes the radio receiver) and an antenna 13. As an alternative, the antenna can be a part of the PCB. The RTU is encased in a box which is installed on a tap (valve) 20 or adjacent the tap, and connected to a solenoid 21 on the tap. A sprinkler 23 is telescopically mounted above the tap 20 and is free to rise from a lower position at which it lies in a recess 25 in the tap housing 26 to an upper position at which it protrudes above the housing 26. In the lower position, the sprinkler is flush with the top of the housing 26 and with the ground, so that it does not obstruct operation (e.g. golf, farming etc.) and it is protected from damage. In the upper position, it is operational.

The PCB 12, battery 11 and antenna 13 are mounted on the tap for control thereof, positioned below the uppermost part of the tap and its associated sprinkler 23.

The solenoid 21 converts electrical commands from the RTU 10 to hydraulic commands to open/close the flow of water from an underground pipe 22. This in turn controls the operating/stopping of the sprinkler 23, which rises under the pressure of the water to its upper position and falls under gravity.

Such a sprinkler is known as a popNip sprinkler.

The valve 20 may be positioned in the pipe 22 and may control flow of water to a number of sprinklers.

The circuits mounted on PCB 12 are illustrated in FIG. 2.

The board 12 contains a radio receiver 30, logic circuits 31, DIP SWITCH/EEPROM 32 and command circuits 33 to the solenoid.

The radio receiver 30 operates in a low voltage range (1.2-1.5V) and requires a small amount of current (6 milliamperes max.). Its frequency range is UHF, VHF. The logic circuits 31 perform the following operations: controlling radio operation; deciphering data from the radio; mode management (RUN or SLEEP); solenoid control; "reading" inputs and readinglwriting on the EEPROM or DIP-SWITCH reading.

The EEPROM or DIP-SWITCH circuit 32 is intended for saving the important parameters for the control (various addresses, etc.) during periods when the control is not connected to a battery. The EEPROM is read by the logic circuits by serial communication.

The solenoid command circuit 33 charges a condenser (not shown) to the voltage required for commanding the solenoid and discharging the condenser according to the desired command, which will cause a change in the state of the solenoid.

The system can be linked by a pulse indicator to a water meter, or to contact indicators from sensors placed in the vicinity.

In order to attain low energy requirements, the RTU 10 operates in two states - RUN, for short periods of time (measured in milliseconds), and SLEEP, for longer periods of time (measured in seconds). In the RUN state, all the circuits in the PCB 12 are operational (logic, radio receiver, and, if necessary, solenoid control), and the energy requirements are accordingly high. The system will remain in this state for the minimal time necessary to check data from the radio, monitor entries or perform commands. In the SLEEP state, the minimum number of circuits that will allow wake-up to the RUN state at an exact time are active. The energy requirements in this state are extremely small - measured in micro-amperes.The system or RTU sends the radio signal to the controller, giving it the command at such a time which assures that the controller will receive it when it is in the RUN state, and so can decipher and perform the given command accordingly. Optionally, it is possible to "send" an operation program through which the control will continue to be active perform operations - according to the program it receives, and continues to receive, via radio. The communications method protocol is described in UK patent application number . . . . . . entitled "Method of Operation of a Radio System" of Motorola Israel Ltd., filed on the same date as the present application.

During operation in the RUN state, the radio is "on" and the deciphering circuits "check" data. In each case of error identification, resulting from data transmission (radio transmission not according to the defined communication protocols) or from the program (wrong address or CRC, etc.), the receiver is shut off. If an operational order is deciphered, the receiver will shut off and the solenoid control circuits will transfer the command to the solenoid. During operations while in the RUN state, entries from inputs are checked and defined operations are performed according to their state. After performing all the required operations during the RUN state, the control switches to the SLEEP state. The logic circuits "accumulates" various parameters (RTU addresses in the system, etc.) in the EEPROM and reads the data as needed.If the conformation contains DIP-SWITCH only, the data is read from them.

The solenoid 21, controlled by the controller is of the LATCH-DC type.

Solenoid state changes are accomplished by a short electric pulse created by the controller. The solenoid remains in this state until it receives an electric pulse reversing the state. This solenoid requires energy only during the changeover from state to state, and thus is appropriate for use with the control.

The RTU operates over a wide current range (2.4-5V), with a low average requirement (100-200 micro-amperes) under normal conditions. In accordance with this, it is possible to choose a battery or batteries of various types Lithium, Alkaline, etc. - and of various capacities 1 - 10 Ah. Battery capacity defines the length of control operating time between battery changes.

The control can be used as an inexpensive and efficient terminal unit in various SCADA (supervisory control and acquisition of data) systems such as IRRINET, INTRAC or MOSCAD (trade marks of Motorola Isreal Ltd.), particularly those where the controller is intended for use in irrigation.

Systems which benefit from the use of this equipent are: golf course watering systems, park and municipal garden watering systems and the like.

The antenna 13 is preferably as described in UK patent application number . . entitled "Antenna and Method of Manufacture of a Radio", of Motorola Israel Ltd., filed on the same date as the present application. Such an antenna is very efficient underground and enables the RTU to receive command signals from a terrestrial base station (not shown in the accompanying diagrams), that is to say a base station located at or near ground level.

Claims (7)

Claims

1. A remote terminal unit, having a battery source, a radio and an antenna, where the battery, radio and antenna are buried in situ adjacent an element of a system to be controlled or supervised.

2. A remote terminal unit according to claim 1, when connected to a valve of a fluid flow system, for control of fluid flowing in the system.

3. A remote terminal unit according to claim 2, when conected to a flowmeter of a fluid flow system for monitoring of fluid flow in the system, the RTU comprising computation means for control of the valve selectively in response to monitoring of the flow.

4. A radio controlled valve comprising a radio, a battery source, an antenna and a fluid control valve with associated fliud flow elements, where the radio, battery source and antenna are mounted on the valve for control thereof, positioned below the uppermost part of the valve and its associated fliud flow elements.

5. A radio controlled valve according to claim 4, wherein the associated fluid flow elements include a sprinkler and the radio, battery source and antenna are mounted below the sprinkler.

6. A radio controlled valve according to claim 5, wherein the sprinkler is telescopically mounted for movement between an upper, operational position and a lower, dormant position.

7. A radio controlled valve according to claim 6, wherein the radio, battery source and antenna are mounted below lower position of the sprinkler.