Signal interference suppression method and device

Abstract

A method for controlling a device (2), the device (2) comprising at least two sensors (12, 14) and an interference source (30, 32) that interferes with signals (S1, S2) detected by the at least two sensors (12, 14). The method comprises: detecting signals (S1, S2) from a signal source (4, 8, 10) at different time points by the at least two sensors (12, 14), storing data indicating the detected signals (S1, S2) in a memory (82), comparing signal values ​​determined based on the data of the signals (S1, S2) at three different time points stored in the memory (84) with each other to distinguish the signal values ​​into a low signal value, an intermediate signal value and a high signal value, subtracting the intermediate signal value from a current signal value detected by at least one of the at least two sensors (12, 14) to obtain at least one processed signal value (S1', S2'), and controlling the operation of the device (2) based on the processed signal value (S1', S2').

Description

Technical Field

[0001] The present invention generally relates to a method of controlling a device using detected signals, to a device, such as a robotic lawn mower, and to a system including such a device. Background Art

[0002] Various devices, particularly robotic lawn mowers, operate using signals received by the device from an external signal source. The device may include an interference source that interferes with the signal, thereby altering the received signal. This may degrade the quality of the signal-dependent operation of the device.

[0003] As is well known, robot lawn mowers, also called self-propelled lawn mowers. These robot lawn mowers are equipped with rechargeable batteries. The area of ​​the lawn can be defined by a boundary line. The robot lawn mower can use the signals transmitted via the boundary line to determine its position, for example, to navigate and stay within the area. When the remaining charge in the battery falls below a certain level, the robot lawn mower is configured to return to a charging station to recharge the battery. There are different possibilities for returning the robot lawn mower to the charging station. One possible method is that the robot lawn mower, after receiving a command to return to the charging station, continues to move until a boundary line is detected nearby and then follows the boundary line to a charging station provided somewhere along the boundary line. Another option when returning to the charging station is to use a guide line, which the robot lawn mower follows to return to the charging station.

[0004] The interference source of the device, for example, a cutting device including a motor and a blade of a robotic lawn mower, interferes with the signal from the signal source. For example, electromagnetic noise generated by the motor and / or the rotation of the blade may affect the distortion of the signal from the signal source received by the device.

[0005] WO 2020 / 148138 A1 describes the use of a digital signal processor to provide an output corresponding to an average of multiple recorded transmission signal bursts to handle noise conditions. This solution requires fairly complex processing hardware that finds signal bursts in a noisy signal and averages the bursts. In addition, averaging requires recording the signal over a relatively long time span, which results in a long response time. In addition, noise contributions may remain in the averaged signal.

[0006] US2018 / 0199506 A1 proposes to reduce the voltage of the lawn mower cutting blade motor when the wire sensor detects a magnetic field, and restart the cutting blade motor after the magnetic field detection is completed. This can avoid interference caused by the cutting blade motor, but at the expense of reduced cutting efficiency.

[0007] CN 103941600 B describes an automatic working system, including a noise detection device for detecting a noise signal in a surrounding space and generating a detection signal accordingly, and a control device electrically connected to the noise detection device and receiving the detection signal, and filtering out an environmental signal according to the detection signal to attenuate a portion of the processed signal corresponding to the noise signal. Such solutions usually require complex hardware settings. Summary of the invention

[0008] It is an object of the present invention to provide an improved signal interference suppression.

[0009] According to one aspect of the present invention, the purpose is achieved by a method for controlling a device, the device comprising at least two sensors and an interference source, the interference source being capable of interfering with a signal detected by the at least two sensors. The method comprises detecting signals at different time points t1-t3 by at least two sensors, the signals comprising burst signals from an external signal source, storing data indicating the detected signals in a memory, and determining signal values ​​D1-D3 based on the indicative data of the signals at three different time points t1-t3 stored in the memory to distinguish each other. For example, the signal values ​​D1-D3 are divided into a low signal value, an intermediate signal value, and a high signal value, and the intermediate signal value is subtracted from the current signal value detected by at least one of the at least two sensors to obtain at least one processed signal value, and the operation of the device is controlled based on the processed signal value, for example, navigating the device. These steps can be repeated iteratively, for example, the sampling sensor samples the reading of each discrete sample in time.

[0010] It is based on the idea that improved signal interference suppression is provided for an apparatus, in particular a robotic lawn mower, by using a stored reference signal value as a baseline, the reference signal value having no extreme values ​​compared to the other two stored values, so that the reference signal value used as a baseline may not contain burst signals. This allows effective suppression of noise signal interference with very short response times. In addition, there is no need to interrupt the operation of the apparatus for signal detection. A first sensor of the at least two sensors can be used to determine at least one of the low signal value, the intermediate signal value and the high signal value, and a second sensor of the at least two sensors can be used to determine another of the low signal value, the intermediate signal value and the high signal value.

[0011] According to one embodiment, the interference source comprises a rotatable component rotatable about an axis of rotation. Optionally, the method further comprises determining a rotation speed of the rotatable component. The rotatable component may be a periodic noise source for the signals detected by the at least two sensors. The periodic noise may interfere with the burst signal. By determining the rotation speed, the selection of the three different time points may be improved.

[0012] According to one embodiment, the rotatable component is a blade and / or a source of interference comprising a motor, in particular an electric motor. For example, the motor is configured to rotate the blade. The device may be a robotic lawn mower. The motor and / or the blade may be a noise source. By applying the method described herein, a motor and / or a blade may be used that generates relatively strong noise but subtracts the noise component from the detected signal. This allows a wider range of choices when selecting components for manufacturing the device, thereby reducing the manufacturing effort and costs.

[0013] According to one embodiment, the method further comprises determining a first time offset and a second time offset. Optionally, the second time offset is smaller than the first time offset. This allows for simple determination of different time points.

[0014] Interference sources can be designed to generate periodic electromagnetic signals, in particular as an undesirable side effect. Periodic signals may interfere with pulsed signals. The methods and devices described here allow subtracting such interference.

[0015] The at least two sensors include a first sensor and a second sensor. According to one embodiment, the first time offset may be the time for the rotatable component to rotate one, two or more revolutions around the axis of rotation, and / or the second time offset is the time for rotating a portion of the rotatable component from closest to the first sensor to closest to the second sensor. This allows a particularly efficient selection of a reference signal for noise subtraction. For example, the first time offset T1 may be equal to the time for a motor (e.g. a cutting motor) and / or a disk (e.g. a cutting disk) to rotate one revolution. The second time offset T2 may be equal to the time for a portion of a revolution, for example, depending on the number of blades on the cutting disk and / or the number of poles in the motor. For example, for a three-blade cutting disk, the second time offset T2 may be equal to the first time offset divided by three, T1 / 3.

[0016] According to one embodiment, the three different time points t1-t3 include: a first time point t1, for example, offset T1 before the current time T, t1=T-T1, a second time point t2, for example, offset T2 before the current time T, t2=T-T2, and / or, a third time point t3, for example, offset the first time offset T1 and the second time offset T2 before the current time T, t3=T-(T1+T2). For example, the blade rotates in a direction from the first sensor toward the second sensor. Or, it rotates in the opposite direction.

[0017] According to one embodiment, the comparison signal values ​​D1-D3 include: a first signal value D1 determined at a first time point t1, a second signal value D2 determined at a second time point t2 and a third signal value D3 determined at a third time point t3. This allows further improvement of the noise subtraction.

[0018] Optionally, the first sensor is used to determine the first signal value D1, the second sensor is used to determine the second signal value D2, and / or the second sensor is used to determine the third signal value D3.

[0019] According to one embodiment, the signal values ​​D1 - D3 are the signal strengths of the corresponding signals at respective time points t1 - t3 .

[0020] According to one embodiment, a device is provided. The device includes at least two sensors and an interference source, which interferes with the signals detected by the at least two sensors. The device is configured to detect signals at different time points t1-t3 through at least two sensors, the signals including burst signals from the signal source, store data indicating the detected signals in a memory, and determine signal values ​​D1-D3 based on the indicative data of the signals at three different time points t1-t3 stored in the memory to distinguish each other. For example, the signal values ​​D1-D3 are divided into a low signal value, an intermediate signal value, and a high signal value, and the intermediate signal value is subtracted from the current signal value detected by at least one of the at least two sensors to obtain at least one processed signal value, and the operation of the device is controlled based on the processed signal value.

[0021] Regarding the advantages of this device, please refer to the above description of the method of controlling this device.

[0022] According to one embodiment, the at least two sensors include a first sensor and a second sensor. Optionally, one or each of the first sensor and the second sensor is used to sense a magnetic field.

[0023] According to one embodiment, the device comprises a body, and the first sensor and the second sensor are arranged at the body and displaced relative to each other. With this arrangement, the interference of the interference source on the signals detected by the first sensor and the second sensor at a specific time point can be different.

[0024] According to one embodiment, the interference source comprises a rotatable component rotatable about an axis of rotation. Optionally, the first sensor and the second sensor are arranged so that the axis of rotation and the first sensor and the second sensor define a quarter of a circle or a circle less than a quarter of a circle centered on the axis of rotation. More generally, the first sensor and the second sensor can together describe an angle a relative to the axis of rotation. The ratio T2 / T1 of the second time offset divided by the first time offset can be equal to the ratio of the angle a to a complete circle, α / 360°. This allows particularly effective filtering of the portion of the conventional noise in the noise.

[0025] For example, interference sources include a motor and a blade that can be rotated by the motor.

[0026] Optionally, the blade comprises a magnetic material. Using the above method, the portion of the signal induced by such a magnetic blade can be easily filtered out. The blade may be magnetic due to the alloy used and / or due to manufacturing conditions, and avoiding the blade being magnetic may significantly increase manufacturing complexity and limit the choice of materials. Therefore, filtering out interference by software can simplify manufacturing and allow a wider choice in the material of the blade.

[0027] According to one embodiment, the device is a robotic lawn mower.

[0028] Optionally, the apparatus of any embodiment described herein is suitable for executing the method of any embodiment described herein. Conversely, the method of any embodiment described herein can use the apparatus of any embodiment described herein.

[0029] According to one object, a system is provided, comprising a device according to any embodiment described herein and a wire as a signal source, wherein the wire may be a guide wire arranged in a region defined by a boundary line or a boundary line.

[0030] The system may further include a signal generator adapted to send a burst signal via the signal source.

[0031] Thus, a method, device and system are provided that allow for improved signal interference suppression. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be described below with reference to the accompanying drawings, in which:

[0033] Figure 1 is a schematic diagram of a robotic lawn mower system.

[0034] Figure 2 is a schematic diagram of an exemplary embodiment of a robotic lawn mower.

[0035] Figure 3 is an illustration of an exemplary embodiment of a charging station for a robotic lawn mower system.

[0036] Figure 4 is an exemplary block diagram of a control unit in a robotic lawn mower.

[0037] Figure 5 is an exemplary block diagram of a signal generator.

[0038] Figure 6 The underside of a robotic lawn mower is shown.

[0039] Figure 7 shows the different signals detected by the sensors of a robotic lawn mower. DETAILED DESCRIPTION

[0040] Hereinafter, a detailed description will be given of an exemplary embodiment of an apparatus in the form of a robot lawn mower 2 using the wires 4 , 8 as a signal source according to the present disclosure.

[0041] Figure 1 A schematic diagram of a system for controlling a robotic lawn mower 2 by means of guide wires 8 and / or by means of boundary wires 4 is shown. The robotic lawn mower 2, or, it may also be referred to as a self-propelled lawn mower, is battery powered and requires regular charging. The robotic lawn mower 2 is configured to move through an area A surrounded by boundary wires 4 during operation. Obviously, for the sake of clarity, the robotic lawn mower 2 is depicted slightly enlarged. The boundary wire 4 can be configured in many different ways so that it defines an area A in which the robotic lawn mower 2 is allowed to move. The boundary wire 4 is preferably set below the ground in the lawn so that it is not visible, but may also be set on the ground or above the ground. The boundary wire 4 may be an ordinary single-core copper wire. Of course, there are other options well known to those skilled in the art, such as multi-strand wire types. As Figure 1 As shown, the boundary line 4 forms a boundary loop line 4a in the charging station 11. The boundary loop line 4a will be used to guide the robot mower 2 to make charging contact with the charging station 11.

[0042] The system also includes the above-mentioned charging station 11. The charging station itself 11 can be regarded as a place where the robot mower 2 is charged, and, for example, can be provided with a charging station plate 24, onto which the robot mower 2 is guided when docking is performed. In addition, a charging station ring 10 is provided at the charging station 11. The charging station ring 10 is completely provided at the charging station 11, more specifically, mounted on the charging station plate 24.

[0043] The system according to the present disclosure also includes one or more guide wires 8. The guide wires 8 are wires that the robotic mower 2 can follow when returning to the charging station 11, when leaving the charging station 11 to start a mowing cycle, and / or when moving in other difficult-to-find ways. The robotic mower 2 can also be configured to follow the boundary wire 4 back to the charging station 11 and / or leave the charging station 11 to start a mowing cycle.

[0044] The boundary wire 4, the charging station loop 10 and the one or more guide wires 8 are all connected to a signal generator, which provides a current signal, especially an alternating current (AC) signal, specific to each wire and loop, so that the robotic mower 2 can identify the wire or loop it is detecting within the sensing distance. In general, the robotic mower 2 can be configured to detect the magnetic field of different signal wires.

[0045] Now go to Figure 2, an exemplary embodiment of a robot lawn mower 2 will be described in more detail. The robot lawn mower 2 comprises a control unit 22, wheels 20, at least two sensors 12, 14, in particular two sensors 12 and 14, optionally three or four sensors, and a battery 18. Each of the sensors 12, 14 is configured to sense a magnetic field. Optionally, the robot lawn mower 2 comprises exactly two sensors 12, 14. Figure 4 The control unit 22 will be described in more detail and includes a processor 80 for controlling the movement of the robotic lawn mower 2. When the robotic lawn mower 2 is in operation, the sensors 12, 14 can sense the magnetic field generated in the boundary wire 4, the charging station loop 10 and the one or more guide wires 8. The signals of the different wires 4, 8 and the charging station loop 10 are encoded in different ways. The sensed magnetic field, i.e. the signal, is decoded in the control unit 22 to determine from which loop or wire it was received. The robotic lawn mower 2 also includes a charging connector 16.

[0046] It is worth noting that the robot lawn mower 2 has a front-to-rear axis, along which the robot lawn mower 2 moves when it travels straight forward or straight backward. In the present embodiment, the robot lawn mower 2 has a longitudinal extension that coincides with the front-to-rear axis. The two sensors 12, 14 are arranged at the body 34 of the robot lawn mower 2, for example, fixed relative to the body 34, the body 34 being displaced from each other in a direction orthogonal to the front-to-rear axis. In this embodiment, the sensors 12, 14 are arranged in the front area of ​​the robot lawn mower 2 and can be referred to as front sensors 12, 14. The two rear sensors can optionally be arranged at the rear of the robot lawn mower 2 and arranged to be displaced from each other in a direction orthogonal to the front-to-rear axis.

[0047] Figure 3 An exemplary embodiment of a charging station 11 is shown. The charging station 11 comprises a charging station plate 24 on which a charging station ring 10 (also referred to as a far-field ring) and a boundary ring line 4a (also referred to as a near-field ring) are mounted. The charging station 11 further comprises a signal generator 6. Figure 3 As shown, the charging station 11 comprises a charging connector 26 arranged to contact the charging connector 16 of the robotic lawn mower 2 when docked to the charging station 11. The charging connector 26 is mounted on a tower 28 of the charging station 11.

[0048] See also Figure 4, the control unit 22 of the robotic lawn mower 2 will be described in more detail. As described above, the control unit 22 includes a processor 80 and a memory 82. The memory 82 includes a computer program 84, which includes computer program code, i.e., instructions. When the computer program code is executed on the processor 80, the computer program code is configured to perform the method steps performed by the robotic lawn mower 2. The control unit 22 also includes an interface 86, which is used to communicate with the sensors 12, 14 and one or more motors controlling the robotic lawn mower 2, in particular the motor for driving the blade. Reference will be made below to Figure 6 To describe, the control unit 22 is configured to receive, store and process signals from the sensors 12 , 14 .

[0049] The processor 80 may include one, two or more central processing units (CPUs). For example, the processor 80 may include a general-purpose microprocessor, an instruction set processor and / or an associated chipset and / or a special-purpose microprocessor, such as an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or a complex programmable logic device (CPLD). The processor 80 may also include a memory for caching purposes.

[0050] Figure 5 A signal generator 6 is shown, which comprises a processor 60 and a memory 62, the memory 62 comprising a computer program 64, the computer program 64 comprising computer program code, i.e. instructions. The computer program code is configured to implement the method steps performed by the signal generator 6 when the code is executed on the processor 60. The signal generator 6 also comprises an interface 66 for transmitting the generated, for example, AC signal to the boundary line 4, the charging station loop 10 and one or more guide wires 8. In particular as a burst signal. Accordingly, at least one conductor or wire loop 4, 8, 10, or all conductors 4, 8 and wire loops 10 can be fed by the signal generator 6 with a burst signal, wherein two consecutive bursts are spaced apart in time.

[0051] The processor 60 also includes one, two or more central processing units (CPUs). For example, the processor 60 may include a general-purpose microprocessor, an instruction set processor and / or an associated chipset and / or a special-purpose microprocessor, such as an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or a complex programmable logic device (CPLD). The processor 60 may also include a memory for caching purposes.

[0052] like Figure 6 As shown, the robot lawn mower 2 includes at least one blade 32 for cutting the lawn, such as two, three or four blades 32. The blade 32 or each blade 32 may be elongated, in the shape of a disc or other shapes. Figure 6In the example of the robot lawn mower 2, a plurality of blades, namely four, three or two blades 32, are mounted on the cutting disc. The blades 32 can rotate relative to the body 34 of the robot lawn mower 2 about the rotation axis R. The blades 32 can be rotated relative to the body 34 of the robot lawn mower 2 by the motor 30, which in this example is an electric motor and is powered by the battery 18. Figure 6 In the example of the embodiment of the present invention, the cutting disc can be rotated by the motor 30, thereby rotating the blade 32 mounted on the cutting disc. The first sensor 12 and the second sensor 14 are arranged at the same distance from the rotation axis R. The first sensor 12 and the second sensor 14 are arranged in the same plane. Optionally, the angle formed by the two sensors 12, 14 and the rotation axis R is 90 degrees, or 75 degrees, or 100 degrees, or in the range of 45 degrees to 150 degrees, in particular in the range of 75 degrees to 100 degrees.

[0053] The operation of the motor 30 generates a time-varying electromagnetic field which can interfere with the signals emitted by the wires 4, 8 or wire loops 10 in the sensing distance. In addition, the blade 32 may also interfere with these signals due to its dielectric constant. The blade 32 may optionally be made of a magnetic or magnetized material and, when rotating, interfere with the signals for this reason.

[0054] Figure 7 The amplitudes of the different signals S1, S2, S1', S2' are shown relative to time t, thereby illustrating the amplitudes at multiple time points. The first signal S1 detected by the first sensor 12 is shown as the uppermost signal. The second sensor 14 is used to detect the second signal S2 from above. About in the middle of the time span shown in the figure, there is a burst signal from the wire 4, 8 or the wire loop 10, for example, a burst signal from the boundary line 4. The burst signal is detected by the first sensor 12 and the second sensor 14 simultaneously.

[0055] However, both sensors 12, 14 also capture other interfering signal components, in particular interfering signal components from the motor 30 and / or the blade 32. The motor 30 and the blade 32 may also be referred to as interference sources interfering with the signals S1, S2 detectable by the sensors 12, 14. By rotating at a certain rotation speed, the motor 30 and / or the blade 32 are the source of periodic signal components in the signals S1, S2 detected by the sensors 12, 14. As a result, the signal bursts are altered and their reception quality is degraded.

[0056] In order to suppress the interference signal component, the robot mower 2 is configured to detect the signals S1, S2, including the burst signal from, for example, the boundary line 4, as the signal source at different time points, in particular continuously, through the sensors 12, 14. The robot mower 2 is also configured to store data indicating the detected signals S1, S2 in the memory 82, to compare the signal values ​​determined based on the data indicating the signals S1 and S2 at three different time points t1, t2, t3 stored in the memory 84 with each other, to distinguish by classifying the signal values ​​into low signal values, intermediate signal values, and high signal values, so as to subtract the intermediate signal value from the current signal values ​​detected by the sensors 12, 14 to obtain at least one processed signal value S1', S2', and to control its operation based on the processed signal values ​​S1' and S2'.

[0057] The relationship between the amplitude value and time of the processed first signal value S1' and the processed second signal value S2' is as follows: Figure 7 As shown in the third and fourth rows of . It can be directly seen that the interference signal component has been effectively subtracted.

[0058] A particularly effective interference suppression method is described below.

[0059] The control unit 22 determines the rotational speed, for example, in revolutions per minute (RPM), of the blade 32. Thus, the interference signal repetition rate is determined by the control unit 22 and is known to the control unit 22.

[0060] Next, the control unit 22 calculates the first time offset T1 as the time for one complete rotation of the blade 32, and the second time offset T2 as the time difference between the arrival of the blade 32 at the first sensor 12 and the arrival at the second sensor 14. In one embodiment, there are four blades on the cutting disk, and the second time offset T2 can be about one quarter of a complete rotation of the blade 32.

[0061] Using the signals S1 and S2 of the two sensors stored in the memory 84 as corresponding data, the control unit 22 extracts three signal values ​​D1, D2, and D3 from the data at the following time points before the current time T: the first time point t1 is the first time offset T1 before the current time T, t1=T-T1; the second time point t2 is the second time offset T2 before the current time T, t2=T-T2; and the third time point t3 is the sum of the first time offset T1 before the current time T plus the second time offset T2, t3=T-T1-T2. The first signal value D1 is determined as the amplitude of the first signal S1 at the first time point t1, D1=S1(t1). The second signal value D2 is determined as the amplitude of the second signal S2 at the second time point t2, D2=S2(t2). The third signal value D3 is determined as the amplitude of the second signal S2 at the third time point t3, D3=S2(t3). The three signal values ​​D1, D2, and D3 are sorted by the control unit 22 according to their values. Among them, the middle value M is selected as the one that is most likely to not have any burst signal, so it is suitable as a baseline. Using this middle value M, the induced interference component can be removed by subtracting the middle value from the first signal S1 value at the current time T to obtain the processed signal S1' value, S1'(T)=S1(T)-M. The second signal S2 can be used to perform the corresponding calculation. The control unit 22 samples the readings of the sensors 12, 14 at a given sampling rate, and repeats the above calculation of the processed signal S1' value for each sample at the corresponding current time T over time. For example, when the latest signal sample is stored in the memory 84, the oldest sample will be deleted from the memory 84. The control unit 22 can be used to store signal data within a specific time period. The result is as follows Figure 7 The first processed signal S1' and the second processed signal S2' are shown. Using these (or one of them), the robotic lawn mower 2 is operated, in particular navigated. This greatly improves the accuracy of the operation. In addition, the sensors 12, 14 can be arranged closer to the motor 30 and the blade 32. In this way, the size of the robotic lawn mower 2 can also be reduced.

[0062] Figure 7 The widths of the first time offset T1 and the second time offset T2 are also shown. Figure 7 It can be seen that the interference signal component is periodic and repeats after one revolution of the blade 32 corresponding to the first time offset T1. In addition, due to their offset arrangement, the signals recorded by the two sensors 12, 14 are offset by a second time offset T2. Figure 7In the example, since the second sensor 14 is in the opposite direction relative to the first sensor 12, the second signal S2 is reversed relative to the first signal S1. In this case, the value of the second signal S2 can be multiplied by -1 in the above calculation. Alternatively, the two sensors 12, 14 are arranged to have the same direction. The time offset between two consecutive burst signals from the boundary wire 4 (or other guide wires 8 or wire loops 10) is greater than the first time offset T1. That is, the wires 4, 8 and the wire loops 10 are only active for a portion of the time, such as between 1% and 10% of the time, for example, at approximately 4% of the time. However, when the motor 30 is in an activated state, the noise signal is continuously activated.

[0063] Therefore, it can be seen that at any current time T, only the signal values ​​D1, D2, D3 at one of the three points in time t1, t2, t3 can include the contribution of the burst signal. One of the three signal values ​​D1, D2, D3 is most likely to have the highest or lowest amplitude, while the middle one of the three signal values ​​D1, D2 and D3 is most likely to have no contribution of the burst signal and is therefore eligible for removal of the interference signal component.

[0064] To provide an illustrative example, assume three signal values ​​are as follows: D1 = 45, D2 = 33, D3 = 34. An intermediate signal value sample is determined to be a third signal value D3 = 34.

[0065] It is worth noting that, in general, the first time offset T1 can be an integer multiple of a complete rotation of the blade, such as 1, 2, 3 or more. T1 can generally be determined based on the RPM of the blade 32, and T2 can generally be determined based on the fixed relative arrangement of the sensors 12, 14 with respect to the rotation axis R. For example, the signal of the first sensor 12 is cleaned up, for example, to eliminate the interference, by finding a time delayed copy of the interference on the signal of the second sensor 14 and subtracting it from the signal of the first sensor 12. Alternatively or additionally, the signal of the second sensor 14 can be cleaned up, for example, to remove the interference, by finding a time delayed copy of the interference on the signal of the first sensor 12 and subtracting it from the signal of the second sensor. The interference may be the same for each rotation of the blade 32 or cutting disk.

[0066] A method for controlling an apparatus, such as the robotic lawn mower 2 described above, comprises at least two sensors 12, 14 and a source of interference 30, 32 that interferes with signals detectable by the at least two sensors 12, 14. The method comprises the following steps.

[0067] Step S101: Detect signals S1 and S2 at different time points by at least two sensors 12 and 14, where the signals S1 and S2 include burst signals from a signal source (eg, boundary line 4).

[0068] Step S102: Store data representing the detected signals S1, S2 in the memory 82. For this purpose, a FIFO may be used.

[0069] The interference source 30 , 32 may include a rotatable component, such as a blade 32 , rotatable about an axis of rotation R, and the method optionally includes a step S103 of determining the rotation speed of the rotatable component. This may be achieved using the detected signals S1 , S2 and / or based on a set point defined in the control unit 22 .

[0070] Step S104: comparing the signal values ​​determined based on the data of the signals S1, S2 representing the three different time points t1, t2, t3 stored in the memory 84 to classify the signal values ​​into low signal values, intermediate signal values ​​and high signal values. The three different time points t1, t2, t3 can be calculated based on the determined rotation speed and / or using the first time offset T1 and the second time offset T2.

[0071] Step S105: subtract the intermediate signal value from the current signal value detected by at least one of the at least two sensors 12, 14 to obtain at least one processed signal value S1', S2'.

[0072] Step S106 : Controlling the operation of a device, for example, the robotic lawn mower 2 , based on the processed signal values ​​S1 ′, S2 ′.

[0073] Some or all of these steps may be repeated iteratively, for example, at a given sampling rate, in particular steps S104 and S105.

[0074] For example, the computer program 84 of the control unit 22 may include instructions that, when executed by the processor 80, cause the robotic lawn mower 2 to perform the method described above.

[0075] Although the present invention has been described above with reference to specific embodiments, it is not to be limited to the specific forms described herein. Rather, the present invention is limited only by the appended claims.

[0076] In the claims, the term "comprises / comprising" does not exclude the presence of other elements or steps. Furthermore, although listed separately, a plurality of devices or elements may be implemented by, for example, a single unit or processor. Furthermore, although individual features may be included in different claims, these features may be advantageously combined, and the inclusion in different claims does not mean that a combination of features is not feasible and / or advantageous. Furthermore, singular references do not exclude pluralities. The terms "one", "first", "second", etc. do not exclude pluralities. The reference signs in the claims are provided merely as a clarifying example and should not be construed as limiting the scope of the claims in any way.

[0077] Reference numerals list

[0078] 2Robot lawn mower

[0079] 4Boundary Line

[0080] 4a Boundary Loop

[0081] 6Signal Generator

[0082] 8. Leading lines

[0083] 10 Charging Station Ring

[0084] 11 Charging Stations

[0085] 12 Sensors

[0086] 14 Sensors

[0087] 16 Charging connector

[0088] 18 batteries

[0089] 20 wheels

[0090] 22Control Unit

[0091] 24 charging station boards

[0092] 26 Charging connector

[0093] 28 Tower

[0094] 30 Motor

[0095] 32 blades

[0096] 34 Main body

[0097] 60 processors

[0098] 62 Memory

[0099] 64 Computer Programs

[0100] 80 processors

[0101] 82 Memory

[0102] 84Computer Programs

[0103] Area A

[0104] RRotation axis

[0105] S1, S2 signal

[0106] S1', S2' process signals

[0107] T1, T2 time offset

Claims

1. A method for controlling a device, the device (2) comprising at least two sensors (12, 14) and a source of interference (30, 32), the source of interference (30, 32) interfering with signals detectable by the at least two sensors (12, 14), characterized in that The method comprises: Detection (S101): Detecting (S101) signals (S1, S2) at different time points by means of the at least two sensors (12, 14), wherein the signals (S1, S2) include burst signals from a signal source (4, 8, 10); Storing (S102): Storing (S102) data indicative of the detected signal (S1, S2) in a memory (82); Comparing (S104): comparing signal values ​​determined based on data indicating signals (S1, S2) at three different time points stored in the memory (84) with each other (S104) to distinguish the signal values ​​into a low signal value, an intermediate signal value, and a high signal value; Subtracting (S105): subtracting (S105) the intermediate signal value from the current signal value detected by at least one of the at least two sensors (12, 14) to obtain at least one processed signal value (S1', S2'), and Control (S106): Control (S106) the operation of the device (2) based on the processed signals (S1', S2').

2. The method according to claim 1, characterized in that The interference source (30, 32) comprises a rotatable component (32) rotatable about a rotation axis (R), and wherein the method further comprises determining (S103) a rotation speed of the rotatable component (32).

3. The method according to claim 2, characterized in that The rotatable component (32) is a blade, and the interference source (30, 32) further comprises a motor (30) for rotating the blade.

4. The method according to claim 2, characterized in that: Also included is determining a first time offset (T1) and a second time offset (T2) that is smaller than the first time offset (T1).

5. The method according to claim 1, characterized in that: The interference source (30, 32) generates a periodic interference signal.

6. The method according to claim 4, characterized in that The at least two sensors (12, 14) include a first sensor (12) and a second sensor (14), and the first time offset (T1) is the time for the rotatable component (32) to rotate a full circle around the rotation axis (R), and the second time offset (T2) is the time for rotating a portion of the rotatable component (32) from closest to the first sensor (12) to closest to the second sensor (14).

7. The method according to claim 4, characterized in that The three different time points include a first time point at the first time offset (T1) before the current time, a second time point at the second time offset (T2) before the current time, and a third time point at the first time offset (T1) before the current time plus the second time offset (T2).

8. The method according to claim 7, characterized in that The compared signal values ​​include a first signal value determined at the first time point, a second signal value determined at the second time point, and a third signal value determined at the three time points.

9. The method according to claim 8, characterized in that The first signal value is determined using a first sensor (12), the second signal value is determined using a second sensor (14), and the third signal value is determined using the second sensor (14).

10. The method according to claim 1, characterized in that The signal values ​​are the signal intensities of the corresponding signals (S1, S2) at various time points.

11. A device comprising at least two sensors (12, 14) and an interference source (30, 32), wherein the interference source (30, 32) interferes with signals detectable by the at least two sensors (12, 14), characterized in that The device (2) is configured as follows: Detecting, by means of the at least two sensors (12, 14), signals (S1, S2) at different time points, wherein the signals (S1, S2) include burst signals from a signal source (4, 8, 10); storing data indicative of the detected signals (S1, S2) in a memory (82), comparing signal values ​​determined based on data indicating signals (S1, S2) at three different time points stored in a memory (84) with each other to distinguish the signal values ​​into a low signal value, an intermediate signal value, and a high signal value, subtracting the intermediate signal value from a current signal value detected by at least one of the at least two sensors (12, 14) to obtain at least one processed signal value (S1', S2'), and Its operation is controlled based on the processed signal values ​​(S1', S2').

12. The device according to claim 11, characterized in that The at least two sensors (12, 14) include a first sensor (12) and a second sensor (14), and each of the first sensor (12) and the second sensor (14) is configured to sense a magnetic field.

13. The device according to claim 12, characterized in that The device (2) comprises a body (34), and the first sensor (12) and the second sensor (14) are respectively arranged on the body (34) and displaced relative to each other.

14. The device according to claim 13, characterized in that The interference source (30, 32) comprises a rotatable component rotatable about a rotation axis (R), wherein the first sensor (12) and the second sensor (14) are arranged so that the rotation axis (R) and the first sensor (12) and the second sensor (14) define a quarter circle or less than a quarter circle with the rotation axis (R) as the center.

15. The device according to claim 11, characterized in that The interference source (30, 32) includes a motor (30) and a blade (32) rotated by the motor (30).

16. The device according to claim 15, characterized in that The blade (32) comprises a magnetic material.

17. The device according to claim 11, characterized in that The device (2) is a robotic lawn mower.

18. The device according to any one of claims 11 to 17, characterized in that The device (2) is configured to perform the method according to any one of claims 1 to 10.

19. A system, characterized in that: The invention comprises a device (2) according to any one of claims 11 to 18 and a wire as the signal source (4, 8, 10).

20. The system according to claim 19, characterized in that Also included is a signal generator (6) configured to send a burst signal through the signal source (4, 8, 10).

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