Fence signal detection method, circuit, self-propelled equipment and mowing system

Abstract

A method, circuit, self-propelled device and mowing system for detecting a fence signal. The present invention performs several stages of amplification and several stages of anti-aliasing filtering on the signal obtained by the signal receiving end of the self-propelled device, identifies the signal within a set frequency range in the signal obtained by the last stage of anti-aliasing filtering, decodes the signal within the set frequency range, and thereby obtains the fence signal. The present invention uses multi-stage anti-aliasing filtering and multi-stage amplification, in conjunction with a digital phase-locked loop to analyze the frequency, so as to amplify the fence signal and filter out interference signals of different frequencies. Compared with the existing method of directly performing one-stage amplification and / or filtering, the present invention has a stronger anti-interference ability, and in particular, can effectively solve the signal interference problem generated when a self-propelled device with a brushed motor is working, and improve the accuracy of identifying the fence signal.

Description

Technical Field

[0001] The present invention relates to the field of garden tools, and in particular to a fence signal detection method, a circuit, a self-propelled device and a mowing system. Background Art

[0002] Intelligent self-propelled devices have been widely popularized. At present, the working area of ​​most intelligent self-propelled devices is marked by a pre-set fence, and the self-propelled devices perform operations such as mowing within the fence. Usually, the self-propelled device determines whether it is within the fence by detecting a pulse signal on the fence.

[0003] At present, the following two methods are usually used to detect the fence signal: First, the charging station sends several periodic pulse signals through the fence, and the self-propelled device determines whether it is in the fence area by whether it receives these pulse signals; second, the charging station sends a coded pulse signal through the fence, the self-propelled device receives the coded pulse signal, and then decodes it for judgment.

[0004] These two methods are relatively simple and easy to implement and are widely used.

[0005] However, both methods have certain defects, especially the first one. In working environments with signal interference (such as places where wires are laid underground), the first method is easy to misjudge due to interference signals, causing the equipment to work abnormally or run out of the fence.

[0006] The second method has some improvements in anti-interference compared to the first method. However, for stronger interference, the existing second method will still cause abnormal operation and run out of the enclosure. This is especially true for devices where the signal acquisition circuit is close to the motor, especially the brushless motor, or where there is a large alternating signal source or alternating current near the working area. Summary of the invention

[0007] In view of the shortcomings of the prior art, the present invention provides a fence signal detection method, circuit, self-propelled equipment and mowing system. The present invention uses multi-stage anti-aliasing filtering and multi-stage amplification, and cooperates with the method of using a digital phase-locked loop to analyze the frequency, so as to amplify the fence signal and filter out interference signals of different frequencies, and accurately obtain the fence signal. The present invention specifically adopts the following technical solutions.

[0008] Firstly, to achieve the above-mentioned purpose, a method for detecting a perimeter signal is proposed, the steps of which include: performing several stages of amplification and several stages of anti-aliasing filtering on the signal; identifying the signal within a set frequency range in the signal obtained by the last stage of anti-aliasing filtering; decoding the signal within the set frequency range to obtain a perimeter signal.

[0009] Optionally, the above-mentioned enclosure signal detection method is characterized in that, in the process of performing several levels of amplification and several levels of anti-aliasing filtering on the signal: after each level of signal amplification, one level of anti-aliasing filtering is performed respectively until the last level of anti-aliasing filtering is completed; after the last level of anti-aliasing filtering is completed, the signal within a set frequency range in the obtained signal is digitally phase-locked, the signal component with the same frequency as the set frequency in the signal obtained after the last level of anti-aliasing filtering is tracked, the signal component within the set frequency range is identified, and the signal component is decoded according to the decoding time determined by the tracking.

[0010] Optionally, the above-mentioned enclosure signal detection method is characterized in that the first stage amplification of the signal is differential amplification, and the last stage anti-aliasing filtering performed on the signal after the last stage amplification is low-pass filtering; the anti-aliasing filtering performed on the signals after other stages of amplification are all high-pass filtering.

[0011] Optionally, the above-mentioned line signal detection method is characterized in that the step of identifying the signal within the set frequency range in the signal obtained by the last stage of anti-aliasing filtering includes: receiving the indication signal output by the digital phase-locked circuit, and the MCU identifying the signal component in the signal obtained by the last stage of anti-aliasing filtering that is the same as the set frequency range according to the time point indicated by the indication signal.

[0012] A peripheral signal detection circuit comprises: a plurality of stages of amplification units and a plurality of stages of anti-aliasing filtering units, wherein the amplification units at each stage and the anti-aliasing filtering units at each stage are connected to each other at intervals; a signal processing unit, used for identifying a signal within a set frequency range in a signal output by the last stage of the anti-aliasing filtering unit, decoding the signal within the set frequency range, and obtaining a peripheral signal.

[0013] Optionally, the above-mentioned peripheral signal detection circuit is characterized in that the amplification unit includes three stages, and the anti-aliasing filtering unit includes three stages; wherein the output end of the first-stage amplification unit is connected to the first-stage anti-aliasing filtering unit, the output end of the first-stage anti-aliasing filtering unit is connected to the second-stage amplification unit, the output end of the second-stage amplification unit is connected to the second-stage anti-aliasing filtering unit, the output end of the second-stage anti-aliasing filtering unit is connected to the third-stage amplification unit, the output end of the third-stage amplification unit is connected to the third-stage anti-aliasing filtering unit, and the output end of the third-stage anti-aliasing filtering unit is connected to the signal processing unit.

[0014] Optionally, the above-mentioned peripheral signal detection circuit is characterized in that the first-stage amplification unit includes a differential amplification circuit; and the third-stage anti-aliasing filtering unit includes a low-pass filtering circuit.

[0015] Optionally, the above-mentioned perimeter signal detection circuit is characterized in that at least one of the anti-aliasing filtering units at each stage includes a high-pass filtering circuit; the signal processing unit is also connected to a digital phase-locked circuit, and the digital phase-locked circuit outputs an indication signal for indicating the time point corresponding to the signal component in the output signal of the third-stage anti-aliasing filtering unit that is the same as the set frequency range; the signal processing unit is used to receive the indication signal output by the digital phase-locked circuit, and track the signal component in the signal obtained after the last stage of anti-aliasing filtering according to the indication signal that is the same as the set frequency range, identify the signal component within the set frequency range, and decode the signal component according to the time point determined by the tracking to obtain the perimeter signal.

[0016] The present invention also provides a self-propelled device, which includes any of the above-mentioned enclosure signal detection circuits.

[0017] The present invention also provides a mowing system, which includes: a fence signal generating device for generating a fence signal, wherein the fence signal is coded; a fence connected to the fence signal generating device for emitting the fence signal; and a self-propelled device including any fence signal detection circuit as described above.

[0018] Beneficial Effects

[0019] After the present invention performs several stages of amplification and several stages of anti-aliasing filtering on the signal obtained by the signal receiving end of the self-propelled device, the signal within a set frequency range is identified in the signal obtained by the last stage of anti-aliasing filtering, and the signal within the set frequency range is decoded to obtain the surrounding line signal. The present invention uses multi-stage anti-aliasing filtering and multi-stage amplification, and cooperates with the method of analyzing the frequency using a digital phase-locked loop to amplify the surrounding line signal and filter out interference signals of different frequencies. Compared with the existing method of directly performing one-stage amplification and / or filtering, the anti-interference ability of the present invention becomes stronger, and in particular, it can effectively solve the signal interference problem generated when the self-propelled device with a brushed motor is working, and improve the accuracy of identifying the surrounding line signal.

[0020] Furthermore, the present invention sets the first-stage amplification unit to perform differential amplification, which can preliminarily amplify the signal obtained by the receiving end. In particular, it can effectively solve the error caused by the zero-point drift of the signal at the signal receiving end, so that the signal amplification performed by the subsequent stage is more accurate. The present invention also selects the filter circuit as an anti-aliasing filter, which can avoid spectrum aliasing when the signal processing unit performs peripheral signal detection. Each level of anti-aliasing filter unit corresponds to a different passband range, wherein the first few levels can be selected as high-pass filtering, and the last level can be selected as low-pass filtering, which can effectively reduce the interference of each main interference frequency range on the peripheral signal.

[0021] Since the fence is set at the edge of the working area of ​​the self-propelled device and in the middle of the working area, the strength of the fence signal will be significantly reduced. The present invention uses multi-stage amplification to effectively ensure that the signal processing unit of the self-propelled device can obtain effective signals to identify the fence signal, thereby improving the accuracy of identification and avoiding misjudgment of the state and position of the self-propelled device.

[0022] The present invention can accurately identify the signal within the set frequency range in the signal obtained by the last level of anti-aliasing filtering by comparing the indication signal generated by the digital phase lock, thereby improving the accuracy of the identification of the surrounding line signal. In addition, the surrounding line signal is encoded and decoded, which can effectively distinguish the surrounding line signal from other interference signals, further avoiding the misjudgment of the surrounding line.

[0023] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0025] Figure 1 It is a schematic diagram of the overall structure of the surrounding line signal detection circuit of the present invention;

[0026] Figure 2 It is a circuit diagram of a first-stage amplification unit in the enclosure signal detection circuit of the present invention;

[0027] Figure 3 It is a circuit diagram of a first-stage amplification unit in the enclosure signal detection circuit of the present invention;

[0028] Figure 4 It is a circuit diagram of the first several stages of anti-aliasing filter units in the peripheral signal detection circuit of the present invention;

[0029] Figure 5 It is a circuit diagram of the last-stage anti-aliasing filter unit in the peripheral signal detection circuit of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose and technical solution of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as generally understood by those skilled in the art in the field to which the present invention belongs. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with the meanings in the context of the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as herein.

[0032] The meaning of "and / or" in the present invention means that both the cases where each exists alone or both exist at the same time are included.

[0033] The term “connection” as used in the present invention may mean a direct connection between components or an indirect connection between components via other components.

[0034] Figure 1 A circuit for detecting a line signal of a self-propelled device according to the present invention comprises:

[0035] Several stages of amplification units and several stages of anti-aliasing filtering units. Preferably, the amplification units at various stages and the anti-aliasing filtering units at various stages can be connected to each other at intervals, thereby minimizing the amplification of the noise component in the signal;

[0036] The signal processing unit, such as an MCU, is used to identify the signal within a set frequency range in the signal output by the last-stage anti-aliasing filter unit, decode the signal within the set frequency range, and obtain the surrounding signal.

[0037] In a relatively typical implementation, in the above circuit for processing the signal obtained by the receiving end, a three-stage amplification unit and a three-stage anti-aliasing filtering unit may be specifically provided. Among them, the output end of the first-stage amplification unit is connected to the first-stage anti-aliasing filtering unit, the output end of the first-stage anti-aliasing filtering unit is connected to the second-stage amplification unit, the output end of the second-stage amplification unit is connected to the second-stage anti-aliasing filtering unit, the output end of the second-stage anti-aliasing filtering unit is connected to the third-stage amplification unit, the output end of the third-stage amplification unit is connected to the third-stage anti-aliasing filtering unit, and the output end of the third-stage anti-aliasing filtering unit is connected to the signal processing unit.

[0038] The first stage of signal amplification can be achieved by Figure 2 The circuit shown in the figure performs differential amplification. The amplification of other levels of signals can be achieved by Figure 3 The circuit shown in the figure can realize the last stage of anti-aliasing filtering of the signal after the last stage of amplification by Figure 5The circuit shown in the figure performs low-pass filtering; the anti-aliasing filtering of the signals after other stages of amplification can be performed by Figure 4 The circuit shown performs high pass filtering.

[0039] In a more specific implementation, after receiving the signal, the signal receiving end of the self-propelled device first outputs the signal to the first-stage amplification unit. The first-stage amplification unit, such as Figure 2 The circuit is set at the front stage of the receiving circuit to preliminarily amplify the received weak surrounding line signal, and then send the amplified signal to the first stage anti-aliasing filter unit. It can be set to perform differential amplification, which can effectively solve the error caused by the zero drift of the signal at the signal receiving end, so that the signal amplification performed by the subsequent stage is more accurate. This stage of amplification can be selected as a differential amplifier circuit realized by the following structure:

[0040] First amplifier;

[0041] A first differential amplifier input resistor, connected to a first input terminal of the first amplifier, and receiving a first input signal;

[0042] A second differential amplifier input resistor connected to a second input terminal of the first amplifier and receiving a second input signal;

[0043] A differential amplification reference resistor, one end of which is connected to the second input end of the first amplifier, and the other end of which is connected to a reference level;

[0044] The differential amplifier feedback resistor is connected between the first input terminal and the output terminal of the first amplifier.

[0045] The first stage anti-aliasing filter unit, such as Figure 4 or Figure 5 The circuit filters the signal after preliminary amplification to filter out the frequency signal that is not within the set range. The filtered usable signal is sent to the second-stage amplification unit. Anti-aliasing filtering can avoid spectrum aliasing when the signal processing unit detects the surrounding line signal.

[0046] The second stage amplification unit, such as Figure 3 The circuit amplifies the filtered available signal again. When a self-propelled device such as a lawn mowing robot performs mowing and other operations in a working area such as a lawn, the working area such as the lawn has different areas, and the strength of the fence signal obtained by the self-propelled device at different positions within the field will be different, and the strength of the fence signal in the middle of the field will be significantly weakened. Therefore, the present invention generally needs to further amplify the middle signal of the field through the second-stage amplification unit, and then output the amplified signal to the second-stage anti-aliasing filter unit.

[0047] The second stage anti-aliasing filter unit, such as Figure 4 , Figure 5The circuit can filter the signal after the second stage amplification again to filter out noise and frequency signals that are not within the set range, and send the filtered usable signal to the third stage amplification unit.

[0048] The third stage amplification unit, such as Figure 3 The circuit fully amplifies the available signal after the second stage anti-aliasing filtering.

[0049] The third level anti-aliasing filter unit, such as Figure 4 , Figure 5 The circuit filters the signal after the third stage is fully amplified again to remove the noise. The signal after the noise is filtered is then sent to the signal processing unit or controller implemented by MCU, FPGA, DSP, etc.

[0050] by Figure 4 Taking the high-pass filter circuit provided as an example, the anti-aliasing filter circuit can be implemented in the following way:

[0051] A second amplifier;

[0052] An input terminal capacitor, comprising two capacitors connected in series, one end of which is connected to the input signal and the other end of which is connected to the second input terminal of the second amplifier;

[0053] A first high-pass reference resistor, one end of which is connected to a reference level, and the other end of which is connected to a first input end of the second amplifier;

[0054] A second high-pass reference resistor, one end of which is connected to the reference level, and the other end of which is connected to the second input terminal of the second amplifier;

[0055] The high-pass feedback resistors include two resistors, one of which is connected between the output terminal and the second input terminal of the second amplifier, and the other of which is connected between the output terminal of the second amplifier and the common terminal of the two input terminal capacitors connected in series.

[0056] by Figure 5 Taking the low-pass filter circuit provided as an example, the anti-aliasing filter circuit can be implemented in the following way:

[0057] A third amplifier;

[0058] An input resistor, comprising two resistors connected in series, one end of which is connected to the input signal and the other end of which is connected to the second input end of the third amplifier;

[0059] A first low reference resistor, one end of which is connected to the reference level, and the other end of which is connected to the first input end of the third amplifier;

[0060] A reference capacitor, one end of which is connected to the reference level, and the other end of which is connected to the second input end of the third amplifier;

[0061] a low-pass feedback resistor connected between the output terminal and the first input terminal of the third amplifier;

[0062] A low-pass feedback capacitor is connected between the output terminal of the third amplifier and the common terminal of the input resistor.

[0063] The aforementioned anti-aliasing filter units at each level can set their component parameters respectively, so that each level of filtering corresponds to a different passband range. The anti-aliasing filter of the first few levels can be selected as a high-pass filter, and the anti-aliasing filter of the last level can be selected as a low-pass filter. The design of different passband ranges can effectively reduce the interference of each main interference frequency range on the surrounding line signal, so as to improve the signal-to-noise ratio of the signal input to the signal output reasonable unit, and accurately restore and identify the surrounding line signal.

[0064] The signal processing unit or controller also receives a digital phase-locked signal as an indication signal at the same time. The indication signal can be realized by a digital phase-locked circuit. After the output signal of the third-level anti-aliasing filter unit enters the digital phase-locked loop, the digital phase-locked loop circuit locks and tracks the set same-frequency signal, outputs an indication signal, indicates the time point corresponding to the signal component in the output signal of the third-level anti-aliasing filter unit that is the same as the set frequency range, and outputs the indication signal to the MCU controller at the same time. Thus, the MCU controller receives the indication signal output by the digital phase-locked circuit, tracks the signal component in the signal obtained after the last level of anti-aliasing filtering that is the same as the set frequency range according to the indication signal, identifies the signal component in the set frequency range, and decodes the signal component according to the time point determined by the tracking to obtain the surrounding signal. The MCU of the present invention can identify the signal corresponding to the set frequency range in the signal obtained by the last level of anti-aliasing filtering at the determined time point of the indication signal, decode the signal in the set frequency range, and obtain the surrounding signal.

[0065] In a more preferred implementation, the phase-locked loop circuit is used for frequency identification and indication. It can be implemented by a digital phase-locked loop frequency analysis unit. After the digital phase-locked loop frequency analysis unit identifies the frequency in the input signal obtained by it that meets the set frequency range, it outputs an indication signal to the MCU. Specifically, the digital phase-locked loop frequency analysis unit first tracks the signal component in the received signal that is the same as the set frequency range to achieve frequency identification, and then triggers the MCU to decode at the corresponding time by outputting an indication signal to the MCU. In this way, when there is no indication signal, the MCU does not need to process, which can reduce the amount of calculation of the MCU, thereby saving MCU resource overhead.

[0066] The specific parameters of the components in the above-mentioned circuits can be adjusted according to the test experiments to match the operating environment of the working area. They can also be set within a reasonable range according to more common operating conditions.

[0067] Therefore, the self-propelled device of the present invention can accurately identify the encoded enclosure signal, filter out the interference of the motor on the enclosure signal, thereby recovering the correct enclosure signal from the noise, and then judge the position of the self-propelled device based on the identified enclosure signal to achieve more accurate walking control.

[0068] The above is only an embodiment of the present invention, and its description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for detecting a peripheral signal, characterized in that the steps include: Perform several stages of amplification and several stages of anti-aliasing filtering on the signal; Identify the signal within a set frequency range in the signal obtained by the last stage of anti-aliasing filtering; Decode the signal within the set frequency range to obtain the surrounding signal; In the process of performing several levels of amplification and several levels of anti-aliasing filtering on the signal: after each level of amplification of the signal, one level of anti-aliasing filtering is performed respectively until the last level of anti-aliasing filtering is completed; After completing the last level of anti-aliasing filtering, the signal within the set frequency range in the obtained signal is digitally phase-locked, the signal component with the same frequency as the set frequency in the signal obtained after the last level of anti-aliasing filtering is tracked, the signal component within the set frequency range is identified, and the signal component is decoded according to the decoding time determined by the tracking.

2. The method for detecting a peripheral line signal according to claim 1, wherein: The first stage amplification of the signal is differential amplification, the last stage anti-aliasing filtering of the signal after the last stage amplification is low-pass filtering; the anti-aliasing filtering of the signals after other stages of amplification is high-pass filtering.

3. The method for detecting a peripheral signal according to claim 1, wherein: The step of identifying a signal within a set frequency range in a signal obtained by the last stage of anti-aliasing filtering includes: receiving an indication signal output by a digital phase-locked circuit, and identifying a signal component in the signal obtained by the last stage of anti-aliasing filtering that is the same as the set frequency range according to a time point indicated by the indication signal.

4. A circuit for detecting a peripheral signal, characterized in that: Using the peripheral signal detection method according to any one of claims 1 to 3, the peripheral signal detection circuit comprises: a plurality of stages of amplification units and a plurality of stages of anti-aliasing filter units, wherein the amplification units at each stage and the anti-aliasing filter units at each stage are connected to each other at intervals; The signal processing unit is used to identify the signal within a set frequency range in the signal output by the last-stage anti-aliasing filter unit, decode the signal within the set frequency range, and obtain the surrounding signal.

5. The circuit for detecting a surrounding line signal according to claim 4, characterized in that: The amplification unit includes three stages, and the anti-aliasing filtering unit includes three stages; wherein, The output end of the first-stage amplifying unit is connected to the first-stage anti-aliasing filtering unit, the output end of the first-stage anti-aliasing filtering unit is connected to the second-stage amplifying unit, the output end of the second-stage amplifying unit is connected to the second-stage anti-aliasing filtering unit, the output end of the second-stage anti-aliasing filtering unit is connected to the third-stage amplifying unit, the output end of the third-stage amplifying unit is connected to the third-stage anti-aliasing filtering unit, and the output end of the third-stage anti-aliasing filtering unit is connected to the signal processing unit.

6. The circuit for detecting a surrounding line signal according to claim 5, characterized in that: The first-stage amplification unit includes a differential amplification circuit; the third-stage anti-aliasing filtering unit includes a low-pass filtering circuit.

7. A self-propelled device, characterized in that: It comprises the surrounding line signal detection circuit as claimed in claim 4.

8. A mowing system, characterized in that: include: A perimeter signal generating device, used for generating a perimeter signal, wherein the perimeter signal is coded; A perimeter line connected to the perimeter line signal generating device for generating the perimeter line signal; A self-propelled device comprising the enclosure signal detection circuit as claimed in claim 4.

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