Mowing robot, and automatic steering calibration method therefor

Abstract

A mowing robot, and an automatic steering calibration method therefor. The automatic steering calibration method comprises the following steps: controlling a steering wheel (4) to turn towards a first limit position until the steering wheel (4) reaches the first limit position, and in this case, recording a first voltage which is output by at least one linear Hall sensor; controlling the steering wheel (4) to turn towards a second limit position until the steering wheel (4) reaches a second limit position, and in this case, recording a second voltage which is output by the at least one linear Hall sensor; on the basis of the first voltage and the second voltage, determining or correcting a mapping relationship between the output voltage of the linear Hall sensor and a steering angle, and obtaining a third voltage which is output by at least one corresponding linear Hall sensor when the steering wheel (4) straightly faces ahead; and controlling a steering electric motor (5) to rotate until the voltage which is output by the at least one linear Hall sensor is equal to the third voltage.

Description

A lawn mowing robot and automatic steering calibration method thereof Technical Field

[0001] The present invention belongs to the field of autonomous operation equipment, and in particular relates to a lawn mowing robot and an automatic steering calibration method thereof. Background Art

[0002] Lawn mower robots can automatically and precisely mow lawns, greatly facilitating lawn maintenance and possessing promising application prospects. Existing lawn mower robots consist of a top cover, a chassis, and a mobile mechanism. The mobile mechanism drives the chassis along a path and typically includes wheels and a motor to drive the wheels. The chassis is connected to the mobile mechanism and carries the blades or motor for cutting the lawn. The top cover, which covers the chassis, protects it from damage and also enhances its aesthetics.

[0003] The moving mechanism generally includes two left and right drive wheels at the rear and a steering wheel at the front. The two drive wheels steer via differential control, while the steering wheel is controlled by a steering motor. As shown in Figure 1, the linear Hall sensor 10 is positioned directly above the square magnet 20, which is located directly above the output shaft 40 of the steering motor 30. The square magnet 20 steers synchronously with the direction of the motor. The steering calibration method for existing lawn mower robots requires manual pre-positioning. Specifically, the steering motor must be manually rotated to the front before leaving the factory. Due to the error in the magnet itself, the data recorded by all machines will be different. Therefore, the position of the manually adjusted magnet must be read first; this is then recorded in the EEPROM of the microcontroller before control can be performed. Otherwise, the motor's steering cannot be controlled. The need for manual pre-positioning is very cumbersome and inefficient. Furthermore, errors in manual alignment reduce the accuracy of the steering calibration.

[0004] Summary of the Invention

[0005] The purpose of the present invention is to provide a lawn mowing robot and an automatic steering calibration method thereof to solve the above-mentioned problems. To this end, the technical solution adopted by the present invention is as follows:

[0006] According to one aspect of the present invention, a method for automatically calibrating the steering of a lawn mower robot is provided. The lawn mower robot includes a drive wheel and a steering wheel, wherein the steering of the steering wheel is controlled by a steering motor. The lawn mower robot also includes at least one linear Hall sensor and a permanent magnet. The permanent magnet is disposed on a component that rotates synchronously with an output shaft of the steering motor, and the at least one linear Hall sensor and the permanent magnet are arranged such that an output voltage of the at least one linear Hall sensor has a unique mapping relationship with a steering angle of the steering wheel. The method for automatically calibrating the steering comprises the following steps:

[0007] controlling the steering wheel to rotate toward a first limit position until the steering wheel reaches the first limit position, and recording a first voltage output by the at least one linear Hall sensor at this time;

[0008] controlling the steering wheel to rotate toward a second limit position until the steering wheel reaches the second limit position, and recording a second voltage output by the at least one linear Hall sensor at this time;

[0009] Determine or modify the unique mapping relationship according to the first voltage and the second voltage to obtain a third voltage output by the at least one linear Hall sensor corresponding to when the steering wheel is in the front direction;

[0010] The steering motor is controlled to rotate until the voltage output by the at least one linear Hall sensor is equal to the third voltage.

[0011] In one embodiment, the at least one linear Hall sensor includes two linear Hall sensors, wherein the two linear Hall sensors are located on both sides of a central plane and directly above the motion trajectory of the permanent magnet, wherein the central plane is parallel to the front of the lawn mowing robot, the output shaft of the steering motor is located on the central plane, and the first limit position and the second limit position are left-right symmetrical about the central plane; wherein the distance between the permanent magnet and the linear Hall sensor on the first side is a=2r sin(α / 2), and the distance between the permanent magnet and the linear Hall sensor on the second side is b=2r cos(α / 2), wherein r is the distance from the permanent magnet to the rotation center of the steering motor, and α is the angle between the permanent magnet-the rotation center-the linear Hall sensor on the first side; wherein the ratio of a and b represents the direction of the steering motor.

[0012] In one embodiment, the two linear Hall sensors are respectively arranged at the first extreme position and the second extreme position.

[0013] In one embodiment, when the steering wheel faces straight ahead, the permanent magnet is located on the central plane.

[0014] In one embodiment, the at least one linear Hall sensor includes a linear Hall sensor, which is located directly above the motion trajectory of the permanent magnet, wherein the distance between the permanent magnet and the linear Hall sensor is d = 2r sin(α / 2), wherein r is the distance from the permanent magnet to the rotation center of the steering motor, and α is the angle between the permanent magnet, the rotation center, and the linear Hall sensor; wherein the d value or the corresponding output voltage of the linear Hall sensor represents the direction of the steering motor.

[0015] In one embodiment, the permanent magnet is located at the first extreme position or the second extreme position.

[0016] In one embodiment, the at least one linear Hall sensor is arranged on a main control board of the lawn mowing robot.

[0017] In one embodiment, the permanent magnet is a circular magnetic steel.

[0018] In one embodiment, the unique mapping relationship is determined by establishing a mapping function or a mapping table.

[0019] In one embodiment, the steering automatic calibration method further includes:

[0020] Before the mowing robot departs from a docking station each time, the steering wheels are automatically calibrated.

[0021] In one embodiment, the steering automatic calibration method further includes:

[0022] When the lawn mowing robot is in a working state, when it is detected that the difference between the first voltage or the second voltage and the first voltage or the second voltage recorded during the last automatic steering calibration is greater than an error threshold, automatic steering calibration is performed.

[0023] In one embodiment, the robotic lawn mower is controlled to return to a docking station before performing automatic steering calibration.

[0024] In one embodiment, the modification of the unique mapping relationship includes modifying parameters of the linear Hall sensor.

[0025] According to another aspect of the present invention, a lawn mowing robot is provided. The lawn mowing robot includes a main control board storing a computer program. When the main control board executes the computer program, the steps of the automatic steering calibration method described above are implemented. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG1 is a partial cross-sectional view of a steering wheel assembly of a conventional lawn mowing robot, showing the arrangement structure of a magnet and a linear Hall sensor;

[0027] FIG2 is a side view of the lawn mowing robot of the present invention;

[0028] FIG3 is an exploded view of the steering wheel assembly of the lawn mowing robot shown in FIG2 ;

[0029] FIG4 is a schematic diagram of the arrangement of the magnetic steel and the linear Hall sensor according to the first embodiment of the present invention;

[0030] FIG5 is a schematic diagram of the steering detection principle of the first embodiment of the present invention;

[0031] FIG6 is a schematic diagram of the arrangement of a magnetic steel and a linear Hall sensor according to a second embodiment of the present invention;

[0032] 7 is a schematic diagram of the steering detection principle of a second embodiment of the present invention;

[0033] FIG8 is a flow chart of the automatic steering calibration method of the lawn mowing robot according to the present invention. DETAILED DESCRIPTION

[0034] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings so that the objects, features and advantages of the present invention can be more clearly understood. It should be understood that the embodiments shown in the accompanying drawings are not intended to limit the scope of the present invention, but are only intended to illustrate the essential spirit of the technical solution of the present invention.

[0035] In the following description, for the purpose of illustrating the various disclosed embodiments, certain specific details are set forth in order to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the relevant art will recognize that the embodiments may be practiced without one or more of these specific details. In other cases, well-known devices, structures, and techniques associated with this application may not be shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0036] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any manner in one or more embodiments.

[0037] In the following description, in order to clearly show the structure and working mode of the present invention, many directional words will be used for description, but words such as "front", "back", "left", "right", "outside", "inside", "outward", "inward", "up", and "down" should be understood as convenient terms and should not be understood as restrictive terms.

[0038] As shown in Figures 1-3, the robotic lawn mower comprises a top cover 1, a chassis 2, and a moving mechanism. The moving mechanism drives chassis 2 along its path. Chassis 2 is connected to the moving mechanism and supports the blades and motor used to cut the lawn. The top cover 1, which covers chassis 2, protects it from damage and also enhances its aesthetics.

[0039] Various functional modules, such as an energy module, a detection module, an interaction module, and a control module (also called a main control board), are also mounted on the chassis 2. The energy module is configured to provide energy for the various operations of the mowing robot. The detection module is configured as at least one sensor that senses the environmental parameters of the mowing robot or its own operating parameters. The interaction module is configured to at least receive control command information input by the user, send information that requires user perception, and communicate with other systems or devices to send and receive information. The main control board typically includes at least one processor and at least one non-volatile memory, wherein the memory stores a pre-written computer program or instruction set. The processor controls the execution of the mowing robot's movements, work, and other actions according to the computer program or instruction set. The main control board can be a printed circuit board (PCB) or a flexible circuit board (FPC), etc.

[0040] The moving mechanism generally includes two front and rear drive wheels 3 and a steering wheel 4. The two drive wheels 3 can be steered using differential control, while the steering wheel 4 can be steered using a steering motor 5. Specifically, the steering motor 5 is fixedly mounted within a base 6, and the steering wheel 4 is mounted on a fork 7, which is drivably connected to the output shaft 51 of the steering motor 5. The base 6 includes a base 61 and a cover 62 located on top of the base 61. The base 61 can be connected to the chassis 2 via screws or other means. The cover 62 covers the top surface of the base 61 and can be snap-fitted to the base 61. Furthermore, the base 6 has a housing cavity, within which the steering motor 5 is mounted, with the end of its output shaft 51 extending through the cover 62. A flange 52 is fixed to the end of the output shaft 51. A first gear 53 is fixed to the output shaft 51 (e.g., via a spline). The fork 7 includes a U-shaped fork portion and a rotating shaft 71. The fork portion is U-shaped, with the steering wheel 4 mounted between its two arms. The bottom end of the rotating shaft 71 is fixed to the fork and is movably arranged in the receiving cavity of the base 61. The second gear 54 is fixed (for example, by a spline) on the rotating shaft 71 and meshes with the first gear 53. Therefore, the steering motor 5 can drive the steering wheel 4 to steer.

[0041] The second gear 54 is provided with a first limiting portion 541, and the base 61 of the seat 6 is provided with a second limiting portion 611. The cooperation between the first limiting portion 541 and the second limiting portion 611 limits the steering angle range of the steering wheel 4 (e.g., ±90°). The steering angle of the steering wheel 4 is typically determined by detecting the output voltage generated by the magnet 9 using a linear Hall effect sensor (not shown). In the present invention, the magnet 9 is typically positioned eccentrically relative to the output shaft 51 of the steering motor 5, so that the output voltage of the linear Hall effect sensor and the steering angle of the steering wheel 4 have a unique mapping relationship. Therefore, once the output voltage of the linear Hall effect sensor is detected, the steering angle of the steering wheel 4 can be determined based on a predetermined mapping relationship. Preferably, the magnet 9 is fixed to a component that rotates synchronously with the output shaft 51 of the steering motor 5. In a specific embodiment, the magnet 9 is fixedly mounted to the flange of the flange 52, for example, by gluing it to the flange or by machining a mounting groove in the flange into which the magnet 9 is inserted. The present invention does not limit the mounting method of the magnet 9. The size of flange 52 can be adjusted based on actual needs, thereby adjusting the rotation radius of magnet 9. When the steering wheel assembly is installed on the lawn mower robot, magnet 9 is within the effective detection range of the linear Hall effect sensor. Preferably, linear Hall effect sensor 8 can be fixedly mounted on the main control board (not shown) of the lawn mower robot to avoid wiring. In this case, the main control board should be installed close to magnet 9.

[0042] How to determine the mapping relationship between the output voltage of the linear Hall sensor and the steering angle of the steering wheel 4 is described in detail below.

[0043] Please refer to Figure 4, which shows the arrangement structure of the magnet and linear Hall sensor of the first embodiment of the present invention. In this embodiment, it includes a magnet 9 and two linear Hall sensors 8A and 8B. For the convenience of description, it is defined that when the lawn mowing robot walks in a straight line, the direction X of the steering wheel 4 is directly forward; at the same time, a central plane A is defined, which is parallel to the front, and the output shaft 51 of the steering motor 5 is located on the central plane A. Usually, the left and right steering limit positions of the steering wheel 4 are mirror-symmetrical about the central plane A. In a specific embodiment, with the central plane as the starting point (denoted as 0°), the left turn limit angle is 90° (denoted as -90°), and the right turn limit angle is also 90° (denoted as +90°). It should be understood that the limit angle is not limited to ±90°.

[0044] In this embodiment, when the steering wheel 4 is facing straight ahead, the magnet 9 is located on the center plane A. The two linear Hall sensors 8A and 8B are respectively arranged on both sides of the center plane. In this embodiment, the two linear Hall sensors are symmetrical about the center plane. For example, the linear Hall sensor 8A is located on the first side (for example, the right side), and the linear Hall sensor 8B is located on the second side (for example, the left side). Ideally, the two linear Hall sensors 8A and 8B are located directly above the motion trajectory of the magnet 9. Since the scale variation of the linear Hall sensors 8A and 8B and the magnet 9 in the rotation plane of the magnet 9 is much greater than the height difference between the two in the axial direction, the magnet 9 and the linear Hall sensors 8A and 8B can be considered to be in the same plane. That is, the distance between the linear Hall sensors and the magnet 9 and the output shaft 51 of the steering motor 5 is considered to be equal.

[0045] With the above structure, when controlling the steering motor to rotate left or right, the distance between the magnet 9 and the two linear Hall sensors 8A and 8B changes, and the two linear Hall sensors 8A and 8B will output different voltage values. Since the output voltage values ​​of the linear Hall sensors 8A and 8B are linearly related to the distance x to the magnet 9, that is, E=k·x+p, where k and p are linear Hall sensor parameters; the distance to the magnet 9 can be used to characterize the magnitude of the output voltage value of the linear Hall sensor. Specifically, please refer to Figure 5, let the distance from the magnet 9 to the rotation center be r, the distance from the right linear Hall sensor 8A to the rotation center o be l1, the distance from the left linear Hall sensor 8B to the rotation center o be l2, and the angle between the magnet 9-rotation center o-right linear Hall sensor 8A be α, then the distance from the magnet to the right linear Hall sensor 8A is Distance from magnet 9 to left linear Hall sensor 8B The ratio of a to b is different at any two positions of the magnet 9 in the process of moving from the right limit position to the left limit position, so the ratio of a to b can reflect the direction of the steering wheel. a =k1·a+p1, the output voltage E of the left linear Hall sensor 8B b =k2·b+p2. Preferably, the two linear Hall sensors are of the same model, that is, the linear Hall sensor parameters k and p are the same to simplify the calculation. Therefore, (E a -p) / (E b That is, the ratio of the output voltages of the linear Hall sensors 8A and 8B minus p can reflect the direction of the steering wheel.

[0046] When the left and right linear Hall sensors 8A and 8B are symmetrical about the center plane, when the magnet is located in the center plane (i.e., the steering wheel is facing forward), a = b, l1 = l2, and α = π / 2, then a / b = 1. Based on this configuration, the direction directly in front of the steering wheel can be determined more conveniently and accurately without having to consider the errors between the magnets during production. This is because the consistency of magnets is generally relatively low, while the consistency of linear Hall sensors is relatively high. In other words, the errors between different magnets in the same batch cannot be ignored, while the errors between different linear Hall sensors in the same batch, or even between different batches of linear Hall sensors, can be ignored.

[0047] Therefore, when calibrating the steering of the steering wheel, there is no need to manually align the steering wheel 4. Instead, the mowing robot automatically performs the alignment according to a preset program, thereby improving production efficiency, reducing production costs, and improving steering calibration accuracy.

[0048] To further simplify calculations and save computing power, the two linear Hall sensors 8A and 8B are structurally positioned directly above the rotational trajectory of the magnet 9. In this case, l1 = l2 = r, resulting in a = 2r sin(α / 2), b = 2r cos(α / 2), and a / b = tan(α / 2). As the steering wheel turns from the right extreme position to the left extreme position, α varies from 0° to 180°. Therefore, a / b remains constant throughout the steering wheel's rotation, and the a / b value can be used to infer the steering wheel's rotation angle. Specifically, when the value of a / b is minimum (i.e., the output voltage of the right linear Hall sensor 8A is maximum and the output voltage of the left linear Hall sensor 8B is minimum), the steering wheel 4 is in the right extreme position; when a / b = 1 (the output voltage of the right linear Hall sensor 8A is equal to the output voltage of the left linear Hall sensor 8B), the steering wheel 4 is in the forward position; and when the value of a / b is maximum (i.e., the output voltage of the left linear Hall sensor 8B is maximum and the output voltage of the right linear Hall sensor 8A is minimum), the steering wheel 4 is in the left extreme position. It should be noted that because the above calculations are based on ideal conditions, that is, the magnet and the Hall are considered points and are in the same plane, and they coincide at the extreme position, a or b may be 0. However, in actual use, a and b will only have maximum and minimum values. In other words, the output voltages of the two linear Hall sensors 8A and 8B will have maximum and minimum values, and the extreme position is determined when the ratio of the two is maximum or minimum. These maximum and minimum values ​​are determined through experiments and testing.

[0049] In some embodiments, the technical solution of one magnet and two linear Hall sensors can be used to automatically align and / or correct the front direction of the lawn mower robot. In this case, the steering control of the steering motor can be achieved by, for example, a magnetic code disk installed inside the motor. Furthermore, since the above solution can obtain the deviation angle of the motor relative to the initial direction (front), it can be used to verify the control data of the magnetic code disk. Furthermore, for some embodiments, the magnetic code disk can be omitted and the above solution can be used alone to control the direction of the steering wheel, further reducing costs.

[0050] Please refer to Figure 6, which shows the arrangement of the magnet and linear Hall sensor of a second embodiment of the present invention. This embodiment includes one magnet 9 and one linear Hall sensor 8. In other words, compared to the first embodiment, this embodiment simplifies the structure, retaining only one magnet 9 and one corresponding linear Hall sensor 8.

[0051] Since the maximum central angle corresponding to the movement trajectory of the magnet is 180°, the voltage value output by the linear Hall sensor 8 is unique at any position within the movement range of the magnet 9, so the absolute value of the voltage output by the linear Hall sensor can be used to characterize the steering direction of the steering wheel.

[0052] Specifically referring to FIG7 , let the distance from the linear Hall sensor 8 to the rotation center o be l, the distance from the magnetic steel 9 to the rotation center o be r, the angle between the linear Hall sensor 8-rotation center o-the magnetic steel 9 at the right limit position be α, and the distance from the linear Hall sensor 8 to the magnetic steel 9 at the right limit position be The distance from the linear Hall sensor 8 to the magnet 9 at the left limit position The distance from the linear Hall sensor 8 to the magnet 9 in the center is Then, when the output voltage of the linear Hall sensor 8 is E right =k·a+p, the control module of the mowing robot can determine that the steering wheel has rotated to the right to the limit position. left =k·b+p, the control module of the mowing robot can determine that the steering wheel has rotated to the right to the limit position. mid = k·c+p, the robot's control module can determine that the steering wheel has rotated to the center position (i.e., directly forward). k and p are linear Hall sensor parameters. Similarly, the mapping relationship between the steering wheel's rotation angle and the Hall output voltage can be determined through the characteristics of the linear Hall sensor 8 and a limited number of experiments. The steering wheel's rotation angle can then be inferred from the output voltage of the linear Hall sensor 8.

[0053] To simplify calculations and conserve computing power, the linear Hall sensor 8 is structurally positioned directly above the rotational trajectory of the magnetic steel 9 and at a lateral extreme position, for example, at the right extreme position. Let the angle α between the magnetic steel 9, the rotational center o, and the linear Hall sensor 8 be d = 2r sin(α / 2), and the output voltage of the linear Hall sensor 8 be E = 2kr sin(α / 2) + p. Since k, r, and p are known parameters, the steering angle of the steering wheel 4 can be inferred from the output voltage of the linear Hall sensor 8. For example, when the output voltage of the linear Hall sensor 8 is at its maximum value, the steering wheel 4 is at its right extreme position; when the output voltage of the linear Hall sensor 8 is at its minimum value, the steering wheel 4 is at its left extreme position.

[0054] According to the mapping relationship between the rotation angle of the steering wheel and the output voltage of the linear Hall sensor 8, even when an error occurs in the linear Hall sensor 8, the control module of the lawn mower robot can compare the maximum and minimum values ​​of the output voltage of the linear Hall sensor 8, and then re-establish a mapping table based on these maximum values. Then, according to the mapping table, it can automatically move to the middle position for self-startup positioning without manual intervention, greatly improving work efficiency.

[0055] In the above example, the shape of the magnet 9 is not limited. The present invention preferably uses a circular magnet because multiple circular magnets are already used in other locations of the mowing robot (e.g., the emergency stop button, the lift sensor, etc.), and using magnets of the same specifications helps reduce costs. It should be understood that the magnet 9 can also be other permanent magnets, as long as they can be detected by the linear Hall effect sensor.

[0056] In the above embodiment, the magnetization direction and the polarity direction of the magnet 9 after installation are not limited, as long as they can be compatible with the selected linear Hall sensor.

[0057] In the above embodiment, the positions of the linear Hall effect sensor and the magnet are not restricted; as long as the linear Hall effect sensor can detect the magnet signal at any point within the steering wheel's rotational range, and the magnet signals at any two positions are different, it suffices. Furthermore, because there are mechanical limits at the steering wheel's rotational extremes, and these limits are symmetrical about the center plane, there is no need to specify the positions of the magnet and the linear Hall effect sensor on the horizontal projection plane. That is, when the steering wheel is facing straight ahead, the magnet does not need to be located on the center plane. The linear Hall effect sensor does not need to be symmetrical about the center plane and may not be located at the positions corresponding to the steering wheel's rotational extremes.

[0058] As shown in FIG8 , based on the above embodiment, the automatic steering calibration method of the lawn mowing robot of the present invention may include the following steps:

[0059] 100. Control the steering wheel 4 to rotate toward the first limit position (e.g., the right limit position) until the steering wheel 4 reaches the first limit position, and record the first voltage output by the linear Hall sensor at this time. For example, for the first embodiment, record the first voltage output by the two linear Hall sensors 8A and 8B. and For the second embodiment, the first voltage E1 output by the linear Hall sensor 8 is recorded.

[0060] 200. Control the steering wheel 4 to rotate toward the second limit position (e.g., the left limit position) until the steering wheel 4 reaches the second limit position, and record the second voltage output by the linear Hall sensor at this time. For example, for the first embodiment, record the second voltage output by the two linear Hall sensors 8A and 8B. and For the second embodiment, the second voltage E2 output by the linear Hall sensor 8 is recorded.

[0061] 300. Based on the first and second voltages, the mapping relationship between the output voltage of the linear Hall sensor 8 and the steering angle of the steering wheel 4 is determined (e.g., at the time of shipment or initial use) and / or corrected (e.g., during subsequent use) to obtain a third voltage E3 output by the linear Hall sensor corresponding to when the steering wheel 4 is directly ahead. Specifically, based on the linear Hall sensor output voltage formula E = k·x + p, the two equations corresponding to E1 and E2 are combined to determine the two parameters k and p. Substituting the distance x3 between the linear Hall sensor and the magnet when the steering wheel 4 is directly ahead into E = k·x + p, the third voltage E3 is obtained. Since the distance x between the linear Hall sensor and the magnet corresponds to the steering angle of the steering wheel in a one-to-one correspondence, and their functional relationship has been described above, the mapping relationship between the output voltage of the linear Hall sensor and the steering angle of the steering wheel can be further determined.

[0062] 400. Control the steering motor 4 to rotate until the voltage output by the linear Hall sensor 8 (or 8A and 8B) is equal to the third voltage E3. At this point, the steering wheel 4 faces straight ahead, completing the automatic steering calibration. If the steering motor has its own steering detection sensor, the accuracy of the calibration can be further verified by comparing whether the steering wheel's direction of the steering motor is facing straight ahead.

[0063] Since the third voltage E3 is calculated based on the first voltage E1 and the second voltage E2 measured in real time by a preset program in the control module, the steering error caused by the linear Hall sensor in different working environments can be avoided, ensuring that the lawn mower robot can steer correctly. At the same time, since the steering calibration is performed automatically, the work efficiency is improved and the error caused by manual alignment in the prior art is solved.

[0064] Because the positional relationship between the magnet and the linear Hall sensor, as well as the extreme positions of the steering wheel, are fixed, the linear Hall sensor parameters (e.g., k and p) can be modified using E1, E2, and other known parameters to correct the linear Hall sensor's errors. In some embodiments, the steering wheel's directional control parameters can be calculated in real time using the aforementioned function. In other embodiments, after the mowing robot is calibrated before departure, a mapping table between the steering angle and the Hall output voltage is established or modified based on E1, E2, and other known parameters. The directional control parameters of the steering wheel 4 can then be retrieved from the mapping table.

[0065] Preferably, the aforementioned automatic steering calibration method is performed each time before the robot mower departs from a docking station. That is, when the robot mower is docked at a docking station and meets the departure conditions (a preset departure time or during the working hours), the robot calibrates the steering wheel's steering angle deviation before leaving the docking station and entering the working area. After the calibration is complete, the robot leaves the docking station and enters the working area.

[0066] In some embodiments, when the lawn mower robot is in operation and needs to control the steering wheel to rotate to an extreme position, the steering motor is controlled to rotate in a preset direction to a stalled state (i.e., the steering wheel reaches the extreme position on one side), and the output voltage of the linear Hall sensor in the stalled state is recorded. The current detection value is compared with the output voltage of the linear Hall sensor at the extreme position recorded during the last calibration. If the difference between the two exceeds the error threshold, it is determined that a non-negligible error has occurred in the linear Hall sensor, and the lawn mower robot is controlled to perform steering wheel angle deviation calibration (i.e., automatic steering calibration) according to the above method. In some embodiments, the lawn mower robot is controlled to return to the docking station before performing automatic steering calibration. In some embodiments, the lawn mower robot is controlled to stop walking and perform automatic steering calibration in situ on the lawn. However, in situ calibration can easily damage the lawn and is therefore generally not recommended.

[0067] An embodiment of the present invention further provides a lawn mower robot comprising a main control board, which includes a processor and memory. The memory stores a computer program, wherein the processor, when executing the computer program, implements the steps of the above-described automatic steering calibration method. Preferably, the main control board is positioned near a magnetic steel so that a linear Hall effect sensor mounted on the main control board can detect the magnetic steel signal. Specifically, during steering of the steering wheel, the magnetic steel remains within the effective detection range of the linear Hall effect sensor.

[0068] For example, the computer program may be divided into one or more modules / units, which are stored in the memory and executed by the processor to implement the method of the present invention. The one or more modules / units may be a series of computer program instruction segments capable of performing specific functions, and the instruction segments are used to describe the execution process of the computer program in the robot.

[0069] The control module of the lawn mowing robot may include but is not limited to a processor and a memory. For example, it may also include input and output devices, network access devices, a bus, etc.

[0070] The processor may be a central processing unit (CPU), other general-purpose processors, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), an off-the-shelf field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc. The processor is the control center of the lawn mower robot and connects various parts of the entire lawn mower robot using various interfaces and lines.

[0071] The memory can be used to store computer programs and / or modules. The processor implements various functions of the lawn mower robot, such as walking, positioning, mowing, homeostasis charging, and automatic steering calibration, by running or executing the computer programs and / or modules stored in the memory and accessing data stored in the memory. The memory can primarily include a program storage area and a data storage area. The program storage area can store an operating system and at least one application required for a function, while the data storage area can store operating data of the lawn mower robot, such as a linear Hall sensor and steering angle mapping table. Furthermore, the memory can include high-speed random access memory and non-volatile memory, such as a hard disk, internal memory, a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, at least one disk storage device, a flash memory device, or other volatile solid-state storage device.

[0072] The present invention optimizes the arrangement structure of the magnetic steel and the linear Hall sensor to achieve automatic steering calibration, thereby improving work efficiency and calibration accuracy.

[0073] While the preferred embodiments of the present invention have been described in detail above, it should be understood that, after reading the above teachings of the present invention, those skilled in the art may make various changes or modifications to the present invention. Such equivalents also fall within the scope defined by the appended claims.

Claims

1. A method for automatically calibrating the steering of a lawn mower robot, wherein the lawn mower robot comprises a driving wheel and a steering wheel, wherein the steering of the steering wheel is controlled by a steering motor, wherein: The lawn mowing robot further includes at least one linear Hall sensor and a permanent magnet, wherein the permanent magnet is arranged on a component that rotates synchronously with the output shaft of the steering motor, and the positions of the at least one linear Hall sensor and the one permanent magnet are arranged so that the output voltage of the at least one linear Hall sensor has a unique mapping relationship with the steering angle of the steering wheel, and the steering automatic calibration method includes the following steps: Controlling the steering wheel to rotate toward a first limit position until the steering wheel reaches the first limit position, and recording a first voltage output by the at least one linear Hall sensor at this time; Controlling the steering wheel to rotate toward a second limit position until the steering wheel reaches the second limit position, and recording a second voltage output by the at least one linear Hall sensor at this time; Determine or modify the unique mapping relationship according to the first voltage and the second voltage to obtain a third voltage output by the at least one linear Hall sensor corresponding to when the steering wheel is in the front; The steering motor is controlled to rotate until the voltage output by the at least one linear Hall sensor is equal to the third voltage.

2. The automatic steering calibration method of a lawn mowing robot as claimed in claim 1, characterized in that: The at least one linear Hall sensor includes two linear Hall sensors, wherein the two linear Hall sensors are located on both sides of a central plane and directly above the motion trajectory of the permanent magnet, wherein the central plane is parallel to the front of the lawn mowing robot, the output shaft of the steering motor is located on the central plane, and the first limit position and the second limit position are symmetrical about the central plane; wherein the distance between the permanent magnet and the linear Hall sensor on the first side is a=2r sin(α / 2), and the distance between the permanent magnet and the linear Hall sensor on the second side is b=2r cos(α / 2), wherein r is the distance from the permanent magnet to the rotation center of the steering motor, and α is the angle between the permanent magnet-the rotation center-the linear Hall sensor on the first side; wherein the ratio of a and b represents the direction of the steering motor.

3. The automatic steering calibration method of a lawn mowing robot as claimed in claim 2, characterized in that: The two linear Hall sensors are arranged at the first extreme position and the second extreme position respectively.

4. The automatic steering calibration method of a lawn mowing robot as claimed in claim 2 or 3, characterized in that: When the steering wheel faces straight ahead, the permanent magnet is located on the central plane.

5. The automatic steering calibration method of a lawn mowing robot as claimed in claim 1, characterized in that: The at least one linear Hall sensor includes a linear Hall sensor, which is located directly above the motion trajectory of the permanent magnet, wherein the distance between the permanent magnet and the linear Hall sensor is d=2r sin(α / 2), wherein r is the distance from the permanent magnet to the rotation center of the steering motor, and α is the angle between the permanent magnet-the rotation center-the linear Hall sensor; wherein the d value or the corresponding output voltage of the linear Hall sensor represents the direction of the steering motor.

6. The automatic steering calibration method of a lawn mowing robot as claimed in claim 5, characterized in that: The permanent magnet is located at the first extreme position or the second extreme position.

7. The automatic steering calibration method of a lawn mowing robot as claimed in claim 1, characterized in that: The at least one linear Hall sensor is arranged on the main control board of the lawn mowing robot.

8. The automatic steering calibration method of a lawn mowing robot as claimed in claim 1, characterized in that: The permanent magnet is a circular magnetic steel.

9. The automatic steering calibration method of a lawn mowing robot as claimed in claim 1, characterized in that: The unique mapping relationship is determined by establishing a mapping function or a mapping table.

10. The automatic steering calibration method of a lawn mowing robot as claimed in claim 1, characterized in that: The steering automatic calibration method also includes: Before the mowing robot departs from a parking station each time, the steering wheels are automatically calibrated.

11. The automatic steering calibration method of a lawn mowing robot as claimed in claim 1, characterized in that: The steering automatic calibration method also includes: When the lawn mowing robot is in a working state, when it is detected that the difference between the first voltage or the second voltage and the first voltage or the second voltage recorded during the last steering automatic calibration is greater than an error threshold, the steering automatic calibration is performed.

12. The automatic steering calibration method of a lawn mowing robot as claimed in claim 11, characterized in that: The lawn mowing robot is controlled to return to the docking station and then automatically calibrate the steering.

13. The automatic steering calibration method of a lawn mowing robot as claimed in claim 11, characterized in that: The correction of the unique mapping relationship includes correcting parameters of the linear Hall sensor.

14. A lawn mowing robot, comprising a main control board, wherein the main control board stores a computer program, wherein: When the main control board executes the computer program, the steps of the steering automatic calibration method according to any one of claims 1 to 13 are implemented.

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