System and method for determining the location of a machine

A system is employed for defining a position (location) of a receiving element inside an area surrounded by a wire loop, along the perimeter (a perimeter wire loop), of a work area or other bounded area. In particular, the system can determine whether the receiver is inside or outside the loop, and evaluate its distance from the perimeter wire.

TECHNICAL FIELD

The disclosed subject matter is directed to boundary systems for robots and other autonomous machines, and in particular, to methods and systems for determining robot location within or outside of the bounded areas.

BACKGROUND

Autonomous machines and devices, such as autonomous robots, have been designed for performing various industrial and domestic functions. These domestic functions include lawn mowing, vacuum cleaning, floor sweeping and maintenance. By extending robots to these domestic functions, the person or user employing these robots has increased free or leisure time, as they do not have to expend the time required to perform the aforementioned tasks manually.

Many of these robots and autonomous machines, such as robotic lawnmowers, are designed to cut grass and other vegetation when they are within a bounded area. The bounded area may be formed by a wire or the like, typically placed underground or on the ground, or other marker, to confine the robot to the bounded area.

SUMMARY

The disclosed subject matter includes a system for defining a position (location) of a receiving element (receiver and/or receiver system) inside an area surrounded by a wire loop, along the perimeter (a perimeter wire loop), of a work area or other bounded area. In particular, the system can determine whether the receiver is inside or outside the loop, and evaluate its distance from the perimeter wire. This system is of particular interest for robots working in a defined area, or automatic vehicles that need to follow a wire, but may also be used for other applications such as dog, pet and animal fences, security systems, etc. The system is economical and involves robust implementations of the transmitting and receiving methods.

The system is formed of a perimeter signal generator that transmits signals conducted by the perimeter wire loop and a receiver or receiving circuit and associated control electronics on the robot. The receiver and associated control electronics evaluate parameters including, for example, 1) an amplitude inversely proportional to the distance of the receiver (receiver coil) from the perimeter wire/loop, as well as, 2) the state of whether the receiver (receiver coil) is inside or outside the work area, as defined by the perimeter loop. This is communicated to the control system of the robot or machine, that in turn drives and navigates the robot accordingly.

The disclosed subject matter is directed a robot or machine that includes at least one receiver and a detector, electrically coupled to the receiver. The at least one receiver is for receiving a signal transmitted from a boundary, that may be, for example, a perimeter wire loop that defines the boundary, for example, with a work area inside the loop, and is a closed pathway for signal generation and transmission. The at least one receiver is for receiving a transmitted signal that includes at least one positive pulse and at least one negative pulse within a predetermined interval or period. The detector is for detecting peaks in the received signal. These peaks are, for example, major negative peaks, that are analyzed to determine the location of the robot with respect to the boundary and the work area.

The disclosed subject matter is directed to system for determining the location of a receiver with respect to a boundary. The system includes a boundary marker for defining at least one boundary, the boundary marker for supporting at least one signal being transmitted therethrough, the at least one signal including at least one positive pulse and at least one negative pulse within a predetermined interval (period). The boundary marker may be, for example, a perimeter wire loop that defines the boundary, for example, with a work area inside the loop, and is a closed pathway for signal generation and transmission. There is also at least one receiver system including at least one receiver for receiving the at least one signal, and at least one detector electrically coupled to the at least one receiver, the at least one detector configured for detecting peaks in the at least one signal. The peaks, may be for example, major peaks, such as major negative peaks.

The disclosed subject matter is also directed to a method for determining the location of a receiver. The method includes, providing a first loop including a first portion and a second portion, providing a second loop including the second portion and a third portion, and providing a signal over a first loop and providing the signal over a second loop at a predetermined providing interval. The signal providing is such that at least the first portion is always receiving the provided signal, and the second portion and the third portion are receiving the provided signal in accordance with the predetermined providing interval. The method also includes, receiving the signal, converting the signal to pulses, and counting the pulses for a predetermined receiving interval. The counted pulses for the predetermined receiving interval are analyzed against predetermined pulse counts for the predetermined receiving interval in accordance with the predetermined providing interval to determine the location of the receiver. The signal providing may be by a signal generating unit with an internal switch, that switches between loops in accordance with the providing interval, or the aforementioned switch may be separate and outboard from the signal generating unit, that also switches between loops in accordance with the providing interval. The received signal, is, for example, converted to pulses based on detection of the major peaks, such as the major negative peaks.

The disclosed subject matter is also directed to a method for determining the location of a robot with respect to a boundary. The method includes providing a robot. The robot includes at least one receiver for receiving a signal transmitted from a boundary, the transmitted signal including at least one positive pulse and at least one negative pulse within a predetermined transmission interval or period, least one detector electrically coupled to the receiver for detecting peaks in the signal, and a processor electrically coupled to the at least one detector. The processor is programmed to analyze data corresponding to the detected peaks in the signal for determining the location of the robot with respect to the boundary. The method also includes detecting major peaks in the signal, and analyzing data corresponding to the major peaks detected over a predetermined receiving interval against predetermined data to determine the location of the robot with respect to the boundary. The boundary, may be, for example, defined by a perimeter wire loop that forms a closed pathway for signal generation and transmission, with a work area for the robot inside of the boundary.

The disclosed subject matter is directed to a method for determining the location of a robot with respect to a boundary. The method includes providing a robot. The robot includes at least one receiver for receiving a signal transmitted from a boundary, the transmitted signal including at least one positive pulse and at least one negative pulse within a predetermined period and transmitted at predetermined transmission intervals, for example, to define pulse trains while the signal is being transmitted. The robot also includes at least one detector electrically coupled to the receiver for detecting peaks in the signal. The method also includes detecting major peaks in the received signal corresponding to the time the signal is not being transmitted, and analyzing the data corresponding to the major peaks detected over a predetermined receiving interval against predetermined data, to determine the location of the robot with respect to the boundary. For example, the major peaks detected are major negative peaks, that are converted onto digital data.

DETAILED DESCRIPTION

Turning toFIG. 1, there is shown a system20that includes a robot22, or other autonomous machine (machine), for example, a robotic lawnmower (robot and robotic lawnmower are used interchangeably in this document, with a robotic lawnmower being one type of robot or autonomous machine suitable for use in accordance with the disclosed subject matter), operating within a work area24or other bounded area, along a ground surface25. The robot22is shown operating in a scanning pattern or “foot print”, as shown in broken lines, that is programmed into the control unit104, for example, the main board150in the microprocessor150athereof.

The work area24is defined by a boundary26, formed, for example, of a wire27(a boundary marker) arranged around the perimeter of the work area to define a perimeter wire28or a perimeter wire loop (perimeter wire, perimeter wire loop, and perimeter loop used interchangeably herein). The wire27is proximate to the ground surface25, but is usually buried in the ground.

The perimeter wire28is received in a signal generating unit30. The signal generating unit30generates signals utilized by the robot22for multiple functions, in particular, to determine the specific location of the robot22within the work area24or outside of the work area24, as detailed herein. The perimeter wire loop28defines a closed pathway over which the signal(s) generated by the signal generating unit30travel. Throughout this document, the terms “signal” and “signals” are used interchangeably when referring to the electromagnetic output (e.g., electromagnetic waveforms) generated by the signal generating unit (SGU)30.

For example, the signal(s) output from the signal generating unit30, and emitted through the perimeter wire28are, for example, low frequency electromagnetic signals, that induce magnetic fields. The robot22receives and detects these signals, and based on this receipt, robot location with respect to the work area24, and sections of the work area24(if divided into such sections), is determined.

The wire27of the perimeter wire28is of metal or other electrically conductive metal wire. The wire27for the perimeter wire28may be for example, PERIMETER WIRE for the Robomower, MRK0014A, commercially available from Friendly Robotics (the trading name of the owner of this patent application) of Pardesyia 42815, Israel.

FIGS. 2-4detail an exemplary robot22suitable for operation as part of the system20. The robot22is shown is a robotic lawnmower, as its payload119(FIG. 4) is designed for lawn mowing. However, the robot22may have a payload119designed for numerous other functions, for example, vacuum cleaning, sweeping, snow and debris removal, and the like. The robot22is similar to the robot disclosed in commonly owned U.S. patent application Ser. No. 10/588,179, entitled: Robot Docking Station and Robot for Use Therewith, published as U.S. Patent Application Publication No. US 2007/0142964 A1, and PCT Patent Application No. PCT/IL05/00119 (WO 2005074362), all three of these documents and their disclosures incorporated by reference herein. U.S. patent application Ser. No. 10/588,179, U.S. Patent Application Publication No. US 2007/0142964 A1, are collectively referred to as U.S. patent application Ser. No. 10/588,179. The electronics of the robot are modified to include the receiver system180, as detailed below, integrated with the control system for the respective robot. These modifications are described below.

The robot22includes docking contacts102(transmission parts for the transmission of energy, electricity, signals, or the like), extending forward or laterally from the front side106of the robot22. The docking contacts102are typically parallel to the horizontal or ground surface. These docking contacts102protrude from the body116of the robot22, and are described in detail in U.S. patent application Ser. No. 10/588,179 and PCT/IL05/00119.

There are typically two docking contacts102, at the front (or front end) end of the robot22, electronically linked (e.g., connected or coupled, as shown in broken lines) to the control system104of the robot22, and the power supply126(batteries and associated components). This electrical linkage allows for charging of the power system (not shown) once a sufficient contact is made (as determined by the control system104, for example, there is at least a threshold voltage of, for example, as least 25 Volts, on the docking contacts102), that allows for docking between the robot22and a docking station (also known as a charging station) (when a docking station is present along the perimeter wire loop28), or when the docking station700is off of the perimeter loop28as shown, for example, inFIG. 12. An exemplary docking station, suitable for use herewith, is the docking station disclosed in U.S. patent application Ser. No. 10/588,179 and PCT/IL05/00119, with minor modifications to accommodate the present disclosed subject matter.

The front wheel110, whose axle111extends into a vertical rod section112, is slideably mounted in a vertical orientation in a well114in the body116of the robot22. Within the well114is a sensor (S1)118, that detects wheel110position by detecting the position of the vertical rod section112. The sensor (S1)118may be an electrical contact sensor, ultrasonic or light sensor, or any other position detecting sensor. The front wheel110of the robot22, being slideably mounted in a vertical orientation, is such that when the axle111/rod section112, on which the front wheel110is mounted slides or drops downward to a predetermined level (also caused by lifting the body of the robot20at its front end), the rod section112is out of contact with the sensor (S1)118, linked to the control system104(FIG. 4). As a result, the requisite components of the control system104signal the drive system151b(FIG. 4) to stop movement of the robot22.

The robot22also includes cutting blades120driven by motors (M)122. It also includes and a power supply126, for example, a battery, and front127aand rear127bbumpers, that if depressed will stop the drive system151b, as detailed in U.S. Pat. No. 6,443,509, this document and its disclosure incorporated by reference herein. The front wheel110is passive (and typically has 360° movement), and the navigation system151aand drive system151bcontrol the rear wheels128, to move and steer the robot22.

The control system104for the robot22is shown inFIG. 4, to which reference is now made.FIG. 4is a block diagram showing the relationship of the components, but each of the components may be electrically linked or coupled to any other component, as would be known, for proper operation of the robot22.

InFIG. 4, as well, the control system104includes a main board150, and all electronics, as hardware, software and combinations thereof and other components, necessary for the robot22to perform all of its operations and functions (known as the main board electronics). The main board150includes one or more processors, and, for example, a microprocessor150a, as part of the main board electronics.

A navigation system151ais electrically coupled to the main board150and a drive system151bis electrically coupled to the main board150. The navigation system151aand drive system151bwhen combined define a movement system for the robot22.

The navigation system151afunctions in the mapping operation and for directing the robot22inside the work area24based on its determined location and in accordance with the selected scanning pattern or operative mode, such as the “edge” mode, as detailed herein. The navigation system151aalso directs the robot22when outside of the work area. The navigation system151ais programmable, for example, to allow for navigation in a work area24or the like in generally straight parallel lines, that are also substantially free of repetition. It is also programmable to other scanning patterns (for operation in the work or bounded area24), such as saw tooth, random movement, or the like, useful in scanning a bounded area to provide coverage, and cutting over the entire work area with minimal repetition. The navigation system151aworks cooperatively with the drive system151b, that controls the rear wheels28of the robot22, to move the robot22along a desired course for its desired operation.

The motors (M)122, power supply126, and the various sensors described herein, represented by SENSORS156, are also electrically coupled to the main board150. Specifically the SENSORS156include electronics, known as “glue electronics” that connect the requisite sensors118,158,162,168and any other sensors and the like to the microprocessor150a. A receiver system (RS)180also electrically couples to the control system104, for example, at the main board150. The receiver system (RS)180receives and detects the perimeter signal(s) from the perimeter wire28of the signal generating unit30. The receiver system180detects this signal(s) as being the boundary of the work area24or section thereof, in order to operate within the boundary of the work area24or section thereof, and work, for example in modes, such as the “edge” mode.

The receiver system180also functions to convert the received signal(s) into digital data. The control system104, via the electronics of the main board150, utilizes the digital data for robot operation.

The electronics of the main board150, coupled with the navigation151aand drive151bsystems, function, for example, in moving the robot22toward and back into the work area24, including specific sections of the work area24(when the work area24is divided into sections, as shown for example, inFIGS. 10,11and14and detailed below), from outside the work area, mapping a work area or section thereof, and moving between sections of the work area. When a docking station is present along the perimeter wire loop28, or off the perimeter wire28as detailed inFIG. 12and discussed below, the electronics of the main board150(including the microprocessor150a) are programmed to cause the robot22to, move toward the docking station, dock in the docking station, perform the docking operations associated therewith, as detailed in U.S. patent application Ser. No. 10/588,179 and PCT/IL05/00119, and other functions associated with robot22operation.

The main board electronics are also programmable, such that when the robot22is operating with a docking station700(FIG. 12) along the perimeter loop28, or off of the perimeter loop28, as shown inFIG. 12and detailed below, the robot22will move toward the perimeter loop28to detect the perimeter signal and ultimately move toward the docking station upon detection of a docking event. Example docking events occur when: 1) robot operation is complete (the area within the boundary marker28, the work area24, has been worked); 2) the battery voltage in the robot22reaches (drops to) a predetermined threshold; 3) a predetermined time for robot operation has expired; or 4) a problem in the robot22itself is detected. With a docking event detected, the main board electronics are then programmed, for example, by mapping or the like, to cause the robot22to move toward the docking station700along the perimeter wire28, also as detailed in U.S. patent application Ser. No. 10/588,179 and PCT/IL05/00119.

Alternately, the robot22maps the boundary26by detecting the perimeter wire28and the proximity thereto. This mapping and detection is performed by the navigation system151aand electronics of the main board150(main board electronics), as the robot22traverses the perimeter wire28and maps the work area24, by noting its coordinates, as detailed in commonly owned U.S. Pat. No. 6,255,793, or in accordance with navigation and detection methods disclosed in commonly owned U.S. Pat. No. 6,615,108. U.S. Pat. No. 6,255,793 and U.S. Pat. No. 6,615,108 and their disclosures are incorporated by reference herein.

When a docking station is present along the perimeter wire28, the robot22notes the position of the docking station as part of its mapping, as detailed in U.S. patent application Ser. No. 10/588,179 and PCT IL/05/00119. For example, the electronics of the main bard150of the robot22, are programmed to detect the position of the docking station along the perimeter wire28during its mapping operation or upon its initial placement in the docking station700(FIG. 12), in both on the perimeter and off of the perimeter arrangements, and return to the docking station700, along at least a portion of the perimeter wire28or wire path, when the docking station700is off of the perimeter wire28, as shown for example, inFIG. 12. Also, as detailed below, with the signal from the perimeter wire28detected by the robot22, as detailed below, the navigation151aand drive151bsystems of the robot22can be coordinated, and controlled by the electronics of the main board150, to move the robot22to the docking station700(traveling along at least a portion of the perimeter wire28). This may be, for example, in response to a docking event, detected by the electronics of the main board150.

The electronics of the main board150(main board electronics) control operation of the robot22in various modes, such as an “edge” mode, where the robot22moves following the perimeter wire28, by detecting a perimeter signal in the perimeter wire28. This may occur, for example, after the robot22has worked the work area24within the perimeter wire28. An exemplary edge mode is described in commonly owned U.S. Pat. No. 6,493,613. U.S. Pat. No. 6,493,613 and its disclosure is incorporated by reference herein.

Alternately, the payload119could be replaced with any other payload, such as one for vacuuming, sweeping, and the like.

The docking contacts102, the front wheel sensor (S1)118, and various signal transmitters and receivers (the actual signals detailed below), represented by SIGNALS158, also electrically couple to the SENSORS156. For example, the robot22, via the main board150, can determine that it is in the docking station when the docking contacts102when carrying a voltage of approximately 25 volts or greater. The docking contacts102are also electrically coupled to the power supply126, either directly, or through the main board150, in order to provide recharging of the power supply126, when the robot22is docked in the docking station.

Sensors, for example, voltage sensors on the docking contacts162, are also electrically coupled to the SENSORS156. There are also obstacle sensors168, that are electrically coupled to the SENSORS156.

The receiver system (RS)180is positioned on the robot22to detect the signal(s) being generated by the signal generator30, along any point in the perimeter wire28. The receiver system (RS)180includes a receiver (REC)181that is electrically coupled to a receiver unit (RU)182. The receiver system (RS)180is electrically coupled to the control system104, for example, to the main board150, where data sent from the receiver system180is analyzed, the analysis including the determination of robot location with respect to the perimeter loop28. The electronics of the main board150cause various operations of the robot22in response to the analyzed data (for robot location).

The receiver system (RS)180is shown separate from the control unit104of the robot22, but may be part of the control unit104. Alternately, the receiver unit (RU)182may be a stand alone component, with respect to the control system104of the robot22, or, for example, the receiver unit may be integrated into the main board150. The receiver181is designed to receive the signal(s), for example, the magnetic signal(s) induced by the perimeter wire/loop28and the receiver unit (RU)182is designed to evaluate parameters including, for example, 1) an amplitude inversely proportional to the distance of the receiver181(receiver coil200) from the perimeter wire/loop, as well as, 2) the state of whether the receiver (receiver coil200) is inside or outside the work area, as defined by the perimeter loop28. The magnetic signal is detected as an analog signal and converted to a digital representation, for example, a pulse. The receiver182detects the signals induced by the perimeter wire loop as an analog signals and converts the analog signal(s) to digital pulses. The microprocessor150aof the control unit104, counts the digital pulses to determine the location of the robot22inside or outside of the work area24or section thereof. This location information is then analyzed by the microprocessor150athat signals the main board electronics, to cause the drive system151b, and when necessary, also the navigation system151a, to move the robot22accordingly.

FIGS. 5A-5E, collectively referred to hereinafter asFIG. 5, to which attention is now directed, shows the receiver181and the receiver unit182of the receiver system180in detail, in a schematic (circuit) diagram. The receiver181and the receiver unit182are is coordinated, for example, by being at compatible frequencies, with the signal generating unit30, in order to determine robot22location as detailed below. The receiver unit182is, for example, formed of multiple components and/or circuits. The elements of each component or circuit, as shown inFIG. 5, when not specifically described by manufacturer code in Table 1 below include common circuit elements such as resistors (R) and capacitors (C), that are available from numerous component manufacturers and suppliers. The schematic diagram ofFIG. 5is in accordance with standard conventions for electronic circuits. A catalog of the major elements of the aforementioned circuits, that form the receiver unit182is as follows from Table 1.

The receiver (REC)181includes a coil200(also known as a receiver coil), electrically coupled (for example, electrically connected) to a preamplifier202, that is electrically coupled (for example, electrically connected) to filter circuitry204. The filter circuitry204is electrically coupled (for example, electrically connected) to gain control circuitry206, that is electrically coupled (for example, electrically connected) to an analog signal filter208and (robot) In/Out location detection circuitry210(also known as a detector for detecting robot location with respect to the perimeter loop28), whose output is at CABLE_IN/OUT.

The coil (receiver coil)200is, for example, a 100 micro Henry coil, for receiving the signal from the perimeter wire loop28. While a single coil200is shown, multiple coils may also be used. The received signal is then passed to the receiver unit182. The received signal is amplified in the preamplifier202. The preamplified signal is then subject to filtration in the filtration circuitry204, that is for example, an 8 KHz filter, so as to be coordinated with the frequency of the signal(s) being generated by the signal generating unit30(for example, the frequency of the signal generated by the signal generating unit30is, for example, a 4 KHz signal with a 25% duty cycle, such that the 8 KHz harmonics of the signal pass through the filtration circuitry204. The filtration circuitry204may be at any other frequency, provided it is synchronized with the frequency of the signal(s) being generated by the signal generating unit30.

The selectable gain control circuitry206is for amplifying the signal(s) to ensure an optimal operation of the In/Out detection circuit210that follows. From the gain control circuitry206, the signal(s) is/are fed into the analog signal filter208, that creates a signal CABLE_AN. The signal CABLE_AN is proportional to the amplitude of the signal received in the coil200(and is inversely proportional to the distance of the coil200from the perimeter loop28).

The signal is passed to the In/Out detector circuit210. The In/Out detector circuit210detects major peaks, positive or negative (for example, positive being above the zero lines and negative being below the zero lines inFIG. 9), depending on the current direction through the perimeter loop28from all other minor peaks in the signal. The threshold for a major peak as distinguished from all minor peaks programmed or programmable into the In/Out Detector circuit210.

For example, based on the current direction through the perimeter loop28being clockwise, as detailed herein, the In/Out detector circuit210is, for example, a single transistor negative peak detector Q110, that detects the major negative peaks from the minor negative peaks. Conversely, in alternate embodiments, with the current flowing through the perimeter loop28in the counterclockwise direction (opposite arrow AA inFIG. 1), the receiver unit182would be modified slightly, for example, in the IN/Out Detector Circuit210such that transistor Q110would be an NPN transistor and the positions of VDD and GND (proximate resistor R542) would be reversed. This would allow the In/Out detector210to function as a single transistor positive peak detector, detecting positive major peaks, similar to that for the major negative peaks, as detailed below.

This circuit210and its surrounding components, gives a positive pulse at the CABLE_IN/OUT port, each time a negative major peak is detected in the received signal. The major negative peaks in the received signals are shown, for example, by, points505and506, respectively in the signal representations501a,502ainFIG. 9, detailed further below. The minor peaks, for example, minor negative peaks are points507in the signal representation501ainFIG. 9. (The signal representation502ahas positive minor peaks508). The PN junction of the transistor Q110, together with the capacitor C525and a resistor R541(FIG. 5) functions as a clamping circuit. Adjusting the time constant resulting from the resistance of R541multiplied by capacitance of C525, allows for the rejection of the lower amplitude, minor negative peaks507, resulting in pulses, represented by lines501band502b(the specific pulses corresponding to the major negative peaks505,506indicated as501bxand502bx, respectively), only derived from the higher amplitude, major negative peaks505,506.

Turning back toFIG. 1, the signal generating unit30includes a signal generator (SG)302, electrically coupled with a controller (CSG)304. The signal generator302, is, for example, a low voltage a signal generator, that induces (produces) a signal (e.g., electromagnetic or the like) for the perimeter wire loop28. This low voltage signal generator is, for example, controlled by the controller304, that is, for example, processor based. The controller304is, for example, a processor, such as a microprocessor, programmable or preprogrammed for its signal generating operations.

The signal generator302, for example, drives a bi-polar square signal to the perimeter wire28(either by circuit components or by a microprocessor in the controller304typically as programmed therein). An exemplary bi-polar square signal is shown as represented by line310inFIG. 6. For example, the signal, represented by the line310, is a unique signal, with the distance between consecutive positive pulses314and consecutive negative pulses315at intervals, also known as periods (for the signal(s)), of approximately 250 microseconds (the interval or period represented by the double headed arrow I1), while the distance between a negative pulse314, followed by a positive pulse314of approximately 62.5 microseconds (being represented by the double headed arrow I2). The current in the perimeter wire loop28resulting from this unique signal (represented by the line310) is detailed below.

Expressed generally, in terms of variables for the unique signal above, as represented by the line310, a positive and a negative pulse are spaced by a time period “TP” with an interval or frame being “4TP”. Accordingly, filtration of this signal is performed with a filter of a frequency “F” of “1/(2·TP)”.

An exemplary signal generator302for the signal generating unit30is shown inFIG. 7A-7C, collectively referred to hereinafter asFIG. 7. The elements of each component or circuit, as shown inFIG. 7, when not specifically described by manufacturer code in Table 2 below, include common circuit elements such as resistors (R) and capacitors (C), that are available from numerous component manufacturers and suppliers. The schematic diagram ofFIG. 7is in accordance with standard conventions for electronic circuits. A catalog of the major elements of the aforementioned circuits, that form the signal generator302of the signal generating unit30is as follows from Table 2.

The signal is generated by a microprocessor404of the controller304, and drives an H-bridge of Field Effect Transistors (FETs). This circuit generates two types of signals: the primary, along line406, with a bridge formed of field effect transistors Q13, Q16, Q14and Q17, and the secondary, along line407, with a bridge formed of field effect transistors Q13, Q16, Q15, Q18(wire27/28connection at J2).

The above-mentioned H-Bridge drives the perimeter wire loop28(wire27) (connected to the H-Bridge at J1) through the capacitor C12(180 nano farad) and resistors R21-R24(which creates an equivalent resistance of 150 ohm). The resistors R21-R24regulate the current on the loop (so it can be approximately the same, regardless of the perimeter wire length) as well as compensate for the influence of the inductance of the perimeter wire28(which can become dominant in long wires). The H-bridge high-side is connected to a 40V power-supply410. This power supply410may be another voltage, based on the current desired on the perimeter wire28, to create a signal with a peak current amplitude of about ±200 milli Amperes.

Attention is now directed toFIGS. 1,8and9. InFIG. 1, there is shown an exemplary work area24, bounded by the perimeter wire loop28. The robot22may be either inside the perimeter wire loop28or outside of the perimeter wire loop28, to illustrateFIGS. 8 and 9. InFIG. 1, the current from the signal generating unit30moves clockwise, around the perimeter wire loop28, from OUT to IN, as indicated by the arrow AA. Similarly, the coil200in the robot22is wound in a manner that signals produced by the signal generating unit30will be in phase. Alternately, the current could move through the perimeter wire loop28counterclockwise, with all signal detection and pulse counts reversed for the robot22inside and outside the perimeter wire loop28(and the coil200of the robot22is in phase with the signal generating unit30). For explanation purposes of the subject matter herein, the system will be described with the current moving clockwise around the perimeter loop28(in the direction of Arrow AA) and the coil200of the receiver181in the robot22wound accordingly, to be in phase with the signal generating unit30.

InFIG. 8, there is shown current (along the y axis), as a function of time (along the x axis), with a time interval represented as T1. The current running through the perimeter loop28is represented by the line420. The receiver30is such that there is a phase shift, for example, a 180° (degree) phase shift, between the signal, as received inside the perimeter wire loop28, and outside of the perimeter wire loop28. After the received signal has passed through the filtration circuit204, the signal for the receiving coil200(and the robot22) inside the perimeter wire loop28is represented by the line421, while the signal for the receiving coil200(and the robot22) outside the perimeter loop28is represented by the line422. Line422is a 180° (degree) phase shift from line421. Lines421and422represent received signals for the current being passed through the perimeter wire28, such as the current for the signal shown inFIG. 7, represented by the line310.

FIG. 9, to which attention is now directed, shows the time interval T1, for the filtered signal and the CABLE_IN/OUT signal (at the output U503B, fromFIG. 5) in the cases that the receiver coil200of the robot22is outside the perimeter wire loop28(the filtered signal is501aand the corresponding CABLE_IN/OUT signal is line501b, as converted into pulses), and inside the perimeter loop28(the filtered signal is502aand the corresponding CABLE_IN/OUT signal is line502b, as converted into pulses). Applying negative peak detection, as performed by the negative peak detector Q110shown and described forFIG. 5above, each major negative peak of lines501aand502aresults in a pulse501bx,502bxin corresponding lines501band502b, respectively.

Peaks of the signal, represented by lines501aand502arespectively, in particular, the major negative peaks below the “0” line, also known and referred to as dips, and indicated by505and506in lines501aand502a, respectively are detected. When the robot22is inside the perimeter wire loop28, represented by lines502aand502b, the frequency and accordingly, the major negative peaks are double the frequency of major negative peaks for the robot22outside of the perimeter wire loop28, represented by lines501a,501b. Specifically, there are twice as many major negative peaks506for the signal of the line502a(indicative of the robot22inside the perimeter loop28), as indicated by the pulses502bxof line502b, than (major negative peaks505) for the signal of line501a, as indicated by the pulses501bxof line501b(indicative of the robot22outside of the perimeter loop28). The frequency is indicative of the position of the receiver coil200(on the robot22) (either inside or outside the perimeter loop28). The detection of this frequency “f” is represented as either “f” for the receiver coil200of the robot22outside the perimeter loop28and “2f” for the receiver coil200of the robot22inside the perimeter loop28.

The pulses501bx,502bxof lines501bor502bare input into the control system104of the robot22, for example, as data, such as digital data. The control system104, via the electronics of the main bard150, processes this data to determine robot22location inside or outside of the perimeter loop28and control robot22operation.

Attention is now directed toFIG. 10, that details another system600. This system600employs the robot22in a work area24, with the work area24divided into multiple sections or plots, as would be typical with a lawn, garden or the like. This system600, with the work area24divided into multiple sections allows for the operation of a robot22, or alternately, several robots (or guided vehicles) operating at the same time (each vehicle in a different section or plot), in different sections or plots. The system600allows a detection of various parts on the perimeter loop28, as well as the detection of a border or boundary line between sections of a work area24.

For example,FIG. 10shows the work area24divided into two sections, Section1601, and Section2602. The signal generating unit30includes a switch606or the like, whose default or primary connection is along the outer perimeter608of the work area24, formed by dashed lines610and dotted lines611. A wire614dividing the work area24into Section1601and section2, is represented as the solid line, and is the secondary connection for the switch606.

The signal generating unit30sends the signal(s) through the primary connection of lines610and611and the secondary connection of lines611and614, based upon the position of the switch606. The switch606is, for example, programmed to alternate between the two positions at regular intervals. For example, the switch606is programmed to alternate between the two positions, resulting in a signal sent through the primary connection of lines610and611for approximately 48 milliseconds (ms) and through the secondary connection of lines610and614for approximately 2 ms.

As a result of this alternation, the dashed-line section610receives current 100% of the time the signal(s) is/are being generated by the signal generating unit30. Similarly, the dotted line section611receives current 96% of the time the signal(s) is/are being generated, while line614receives current 4% of the time signals are being generated.

The receiver system180in the robot22measures the period of transmissions in each frame (where a frame is, for example, a 50 millisecond (ms) time interval or period). The receiver system180detects the dominant signal, that is emitted from the nearest wire26of the system600. Once this wire26is detected, the robot22, via the control system104(the main board electronics), determines the location of the robot22, and for example, can determine if the robot22is in Section1601, Section2602, or outside Section1601or outside Section2602. The robot22, as programmed in the control system104(the main board electronics) can operate accordingly, for example, scanning differently based on the specific section in which the robot22is operating, moving into or out the requisite sections or moving along the wire26, following it. For example, if it is desired to mow (operate in) Section2602, the robot22can drive along the perimeter wire28(formed of the dashed line610) from Section1601, until Section2602is detected. The robot22will then turn inside Section2602, and begin to scan Section2602.

One method or process for detecting the transmission periods for the signal(s) in each wire610,611,614is by counting the pulses of the major peak, for example the negative major peak detector described for the microprocessor150aof the main board electronics of the robot22, above (shown inFIG. 4) at each frame of time (for example, approximately 50 ms). With the signal generating unit30generating a 4 KHz signal, and a frame being 50 milliseconds, pulses (counted pulses) for this frame are in Table 3, as follows:

Since each pulse count is unique for the requisite time frame, it is possible to evaluate where the receiver system180and accordingly, the robot22is located with respect to the work area24and the requisite section or outside of the requisite section, according to the pulse count. As per Table 3, wire610receives current 100% of the time, so that 100% of the pulses from the signal (generated by the signal generating unit30) over a 50 millisecond time frame is 400 pulses, for the robot22being inside Section1601. Since there is a phase shift of the received signal outside of the perimeter loop28, from the phase of the received signal inside the perimeter loop28, the received signal is inverted, reducing the number of major negative peaks by one-half outside of the perimeter wire loop28, as shown inFIG. 9. Accordingly, with the robot22outside of Section1601, the received signal for the frame would result in a pulse count of 200 pulses, the decrease of pulses in accordance with the above-described phase shift.

Similarly, wire611receives current 96% of the time, so that 96% of the pulses from the signal(s) (generated by the signal generating unit30) over a 50 millisecond (ms) time frame is 384 pulses, for the robot22being inside Section2602. Since there is phase shift, as detailed above, outside of the perimeter wire loop28, the robot22being outside of Section2602would be 192 pulses, the decrease of pulses in accordance with the phase shift.

FIG. 11shows a system600′ that is similar toFIG. 10, except that Section1601and Section2602are reoriented based on the position of the signal generating unit30and the switch606is separate (outboard) from the signal generating unit30. This switch606may be controlled by a controller630(also a remote controller) electronically linked to the switch606by wired or wireless links, or combinations thereof.

FIG. 12shows an example of a system699using the above described negative peak detection with an off-perimeter charging station700. The charging station700is placed outside the lawn or work area24, off of the perimeter loop28. The work area24and perimeter loop28are represented by line segments702,703,704,705a,705b. There is node708between segments705aand705b, and a junction, indicated by point710. An off perimeter path712from the work area24to the charging station700is represented by line segments714,715. These segments714,715extend from the charging station700to the junction710and connect to segments702and705brespectively. A dashed line segment718extends from the node708to the charging station700, specifically, to a switch720in the charging station700.

For example, the switch720is programmed to alternate between two positions, resulting in a signal sent through the primary connection of segments714,702,703,704,705aand718for approximately 48 milliseconds (ms) and through the secondary connection of segments715,705band718for approximately 2 ms.

As a result of this alternation, the dashed-line segment718receives current 100% of the time the signal(s) is/are being generated by the signal generating unit30. Similarly, the line formed of segments714,702,703,704and705areceives current 96% of the time the signal(s) is/are being generated, while segments705band715receive current 4% of the time signals are being generated.

In an exemplary operation, the robot22moves to the junction710during the “edge” mode, following along the perimeter wire28of the work area24, and then slows down (as programmed into the control unit140, the main board electronics) upon receiving a count of pulses of 100%, for example 400 for one time interval or period of a 50 ms frame) and continue to the charging station700. Upon departure from the charging station700, the robot22will reverse until it meets the 96% signal at the junction710and than turns left, to move along the segment705b, and the remainder of the perimeter loop28(formed of segments705a,704,703and702), to operate in the work area24.

The pulses, as counted by the receiver system180of the robot22, as detailed above, also allow for the robot22to determine its location within the work area24, along the off perimeter path712to the docking station700, and outside of the work area24. The aforementioned pulse counting method also allows the robot22to detect a border or boundary line26during scanning, while the robot travels inside the work area24surrounded by the perimeter loop28.

FIG. 13shows the received signal at the output of the negative peak detector Q110, detailed above, also known as a dip detector, as a line750, when the robot22is approaching the border line614between Section1601and Section2602, as shown inFIGS. 10 and 11, The received signal of line750is, for example, expressed in terms of pulses in pulse trains752(corresponding to the pulses of lines501band502b) and “dead time,” when pulses are not being transmitted (a signal is not being passed through the requisite wire section). For example, at line614, pulses are being transmitted 96% of the “dead time”. The pulses are smoothed over, resulting in smoothed portions754of the signal, with the “dead time” resulting in major negative peaks or dips756. The major negative peaks or dips756in the signal, for each frame (interval, or time period) (Tx), are analyzed in the microprocessor150aof the main board electronics, like the negative peaks ofFIG. 9, as detailed above.

FIG. 14shows a system800similar to the systems20,600and600′, except the work area24is divided into three sections, Section1801, Section2802and Section3803. There is a signal generating unit30and two switches806,807, separate from the signal generating unit30. Each switch806,807has a default or primary connection is along the outer perimeter808of the work area24, represented by dashed lines810, dotted lines811, and dash-dot lines812. Wires, represented by solid lines814and815, respectively, divide Section1801from Section2802, and Section2802from Section3803, are the secondary connections for the switches806,807.

The signal generating unit30sends the signal(s) through the primary connection of lines810,811and812, the secondary connection of line814and the tertiary connection of line815, based upon the position of the switches806,807. The switches806,807, for example, are programmed to be synchronized, such that the switch807connects to line815only when the switch806connects to line811. For example, in a frame of a 50 ms time interval or period, the switches806,807are programmed to alternate between the two positions, resulting in a signal sent through the primary connection of lines810,811and812for approximately 46 milliseconds (ms), through the secondary connection of lines810,811and815for approximately 2 ms, and through the tertiary connection of lines810and814for approximately 2 ms.

As a result of this alternation, the dashed-line section810receives current 100% of the time the signal(s) is/are being generated by the signal generating unit30. Similarly, the dotted line section811receives current 96% of the time the signal(s) is/are being generated, and the dash-dot line812receives current 92% of the time the signal(s) is/are being generated.

The receiver system180in the robot22measures the period of signal transmissions in each frame (where a frame is, for example, 50 millisecond time interval or period). The receiver system180, recognizes the dominant signal and detects the nearest wire26. Once this wire26is detected, the robot22, via the control system104(main board electronics), determines the location of the robot22, in accordance with that detailed above, and, for example, can determine if the robot22is in Section1801, Section2802, Section3803, or outside each of these sections. The robot22, as programmed in the control system104, and can operate accordingly, for example, scanning differently based on the specific section in which the robot22is operating, moving into or out the requisite sections801-803or moving along the perimeter wire28, following it. For example, if it is desired to mow (operate in) Section2802, the robot22can move along the perimeter wire28(formed of the dashed line810) from Section1801, until Section2802is detected. The robot22will then turn inside Section2802, and begin to scan Section2802.

One method or process for detecting the transmission periods for the signal(s) in each wire, represented by the respective lines810,811,812,814and815, by counting the pulses of the negative-peak detector described for the control system104(main board electronics) of the robot22, above (shown inFIG. 5) at each frame of time (for example, approximately 50 ms). With the signal generating unit30generating an 4 KHz signal (as detailed above), and a frame being 50 milliseconds, pulses (counted pulses) for this frame are in Table 4, as follows:

Similar to that described above, forFIGS. 10 and 11, each section of the perimeter wire loop28results in a unique count. Thus, the location of the robot22is determined from the requisite unique count.

All of the systems and methods above have been shown with negative peak detection based on the current direction, for example, clockwise when making reference toFIGS. 1,10-12and14. However, if the current from the signal generating unit30was reversed, for example, counterclockwise when referencingFIGS. 1,10-12and14(or from IN to OUT ofFIG. 1, or in the opposite direction of Arrow AA ofFIG. 1), positive peak detection (for example, major positive peak detection) would be used with the disclosed subject matter, with slight modifications, as detailed above.

The systems, including systems20,600,600′,699,800and embodiments thereof, as described above, are scaleable. They may be applied to as many sections of a work area24as desired in accordance with that detailed above.

The processes (methods) and systems, including components thereof, herein have been described with exemplary reference to specific hardware and software. The processes (methods) have been described as exemplary, whereby specific steps and their order can be omitted and/or changed by persons of ordinary skill in the art to reduce these embodiments to practice without undue experimentation. The processes (methods) and systems have been described in a manner sufficient to enable persons of ordinary skill in the art to readily adapt other hardware and software as may be needed to reduce any of the embodiments to practice without undue experimentation and using conventional techniques.

While preferred embodiments have been described, so as to enable one of skill in the art to practice the disclosed subject matter, the preceding description is intended to be exemplary only. It should not be used to limit the scope of the disclosed subject matter, which should be determined by reference to the following claims.