Navigation system for a greenhouse and navigation method

Abstract

This invention discloses a navigation system and method for greenhouses, relating to the field of agricultural machinery technology. It includes a reflective strip installed inside the greenhouse, parallel to the working ridge; a rotating mechanism mounted on the working equipment, rotatable about a vertical axis, with a swing arm on the rotating mechanism and two laser rangefinders mounted on the swing arm, the laser emission directions of the two laser rangefinders being parallel; the laser rangefinders are used to measure the distance to the reflective strip; and a controller for controlling the rotation of the rotating mechanism to adjust the orientation of the swing arm; the controller also adjusts the travel direction of the working equipment based on the deviation between the measured value of the laser rangefinders and a second preset value, so that the working equipment travels in a straight line; the first preset value is the distance between the two laser rangefinders along the laser emission direction; the second preset value is the nominal distance between one laser rangefinder and the reflective strip when the working equipment is working along the working ridge.

Description

Technical Field

[0001] This invention relates to the field of agricultural machinery technology, specifically to a navigation system and navigation method for greenhouses. Background Technology

[0002] Facility agriculture is an important model for achieving efficient and intensive production. With the development of automation technology, the demand for automated or semi-automated equipment for seeding, fertilization, spraying, and inspection within greenhouses is increasing. However, autonomous navigation of such equipment is one of the key bottleneck technologies for achieving its automation. Currently, mainstream outdoor agricultural machinery navigation relies on the Global Navigation Satellite System (GNSS). However, in greenhouse planting environments, satellite navigation signals are weak and unstable due to obstruction and signal interference from roof glass, greenhouse film, and metal support frames, making them unusable effectively inside the greenhouse.

[0003] To replace satellite navigation, existing technologies attempt to employ AI-based navigation solutions using lidar or visual image processing. However, lidar is expensive, and visual systems suffer from poor recognition stability in environments with uneven lighting, crop shading, and complex and changing backgrounds, making it difficult to clearly define reference points. These factors result in high costs and insufficient robustness for these solutions, preventing their large-scale application in greenhouses at present.

[0004] Therefore, those skilled in the art urgently need a low-cost, simple-to-deploy, stable and reliable greenhouse navigation system to promote the popularization and development of automated or semi-automated operations in greenhouses. Summary of the Invention

[0005] The purpose of this invention is to provide a navigation system and method for greenhouses that is low in cost and can reliably enable working equipment to travel in a straight line.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A navigation system for greenhouses, comprising:

[0008] This includes reflective strips installed inside the greenhouse, which are arranged parallel to the working ridges;

[0009] It also includes a rotating mechanism for mounting on the work equipment, which is rotatable about a vertical axis. The rotating mechanism is equipped with a swing arm, and the swing arm has two laser range sensors spaced apart in a direction other than the vertical axis. The laser emission directions of the two laser range sensors are parallel. The laser range sensors are used to measure the distance to the reflective strip.

[0010] It also includes a controller for controlling the rotation of the rotating mechanism to adjust the orientation of the swing arm so that the difference between the measured values ​​of the two laser rangefinders always tends to a first preset value; the controller also adjusts the travel direction of the working equipment based on the deviation between the measured values ​​of the laser rangefinders and a second preset value so that the working equipment travels in a straight line; the first preset value is the distance between the two laser rangefinders along the laser emission direction; the second preset value is the nominal distance between one of the laser rangefinders and the reflective strip when the working equipment is working along the working ridge.

[0011] Optionally, the first preset value is 0, and the controller further adjusts the travel direction of the working equipment based on the deviation between the measured value of the laser rangefinder and the second preset value, specifically including:

[0012] The controller calculates the average of the measurements from the two laser rangefinders;

[0013] The controller adjusts the direction of travel of the working equipment based on the deviation between the average value and the second preset value.

[0014] Optionally, the controller further adjusts the travel direction of the working equipment based on the deviation between the measured value of the laser rangefinder and the second preset value, specifically including:

[0015] The controller employs a PID control algorithm, a fuzzy control algorithm, or a sliding mode variable structure control algorithm to calculate a steering control quantity based on the deviation between the measured value of the laser rangefinder and a second preset value; and adjusts the travel direction of the working equipment based on the steering control quantity.

[0016] Optionally, the first preset value is 0, and the controller calculates the steering control quantity based on a PID control algorithm, specifically including:

[0017] The controller calculates the deviation value: e(k) = Lt(k) - L0, Lt(k) = (Lt1(k) + Lt2(k)) / 2; where Lt(k) is the average value of the measurements of the two laser ranging sensors at time k, Lt1(k) and Lt2(k) are the measurements of the two laser ranging sensors at time k, e(k) is the deviation value at time k, and L0 is the second preset value;

[0018] An incremental PID control algorithm is adopted. Based on the current and historical deviation values, the steering control quantity to be applied in the current control cycle is calculated as follows: Δω(k)=Kp*[e(k)-e(k-1)]+Ki*e(k)+Kd*[e(k)-2e(k-1)+e(k-2)], where Δω(k) is the steering control quantity to be applied in the current control cycle, and Kp, Ki and Kd are the pre-set proportional, integral and derivative coefficients, respectively.

[0019] Optionally, the working device includes two drive wheels driven by independent servo motors;

[0020] Adjusting the direction of travel of the working equipment based on the steering control amount specifically includes:

[0021] The controller calculates the speed difference between the two drive wheels based on the steering control quantity, and controls the rotation of the two drive wheels based on the speed difference.

[0022] Optionally, the reflective strip is located at the ventilation opening on the side wall of the shed. The reflective strip is connected to a roller shutter mechanism. The roller shutter mechanism rolls up the reflective strip during ventilation and unfolds the reflective strip when the operating equipment is in operation.

[0023] Optionally, the controller is also configured with a temporary occlusion strategy:

[0024] When the laser ranging sensor signal is abnormal, the controller determines it as a temporary obstruction and controls the working equipment to continue traveling in the original direction for a first preset distance or a first preset time period.

[0025] When the laser rangefinder sensor signal returns to normal, the operation equipment continues to move based on the measured value of the laser rangefinder sensor.

[0026] If the laser ranging sensor fails to restore the signal to normal after the work equipment has traveled a first preset distance or a first preset time period, the system is deemed abnormal, and the controller controls the work equipment to stop operating and issues a fault alarm signal.

[0027] Optionally, the controller is further configured with a first travel distance. After the working equipment has traveled the first travel distance, the controller controls the working equipment to stop traveling and issues a prompt message indicating that it has reached the end of the working ridge.

[0028] The present invention also provides a navigation method for navigating working equipment inside a shed, comprising the following steps:

[0029] S1: Lay reflective strips along the direction of the working rows inside the greenhouse;

[0030] S2: Set a second preset value between the laser rangefinder and the reflective strip. There are two laser rangefinders, which are mounted on a swing arm. The swing arm is mounted on the working equipment through a rotating mechanism. The laser emission direction of the two laser rangefinders is perpendicular to the swing arm, and the distance between the two laser rangefinders in the laser emission direction is 0.

[0031] S3: When the operating equipment is in operation, it acquires the measured values ​​of the two laser ranging sensors in real time;

[0032] S4: Calculate the difference between the measured values ​​of the two laser rangefinders, and control the rotating mechanism to rotate according to the difference, so that the difference approaches zero, so that the laser emitted by the laser rangefinder is perpendicular to the reflective strip;

[0033] S5: Calculate the average of the two measured values, and the deviation of the average value from the second preset value;

[0034] S6: Calculate the steering control amount using a control algorithm based on the aforementioned deviation;

[0035] S7: Control the direction of travel of the working equipment based on the steering control amount.

[0036] Optionally, in step S2, the working equipment is manually controlled to walk along the desired path once, and the controller records a stable distance value during the teaching process and sets it as the second preset value.

[0037] The present invention offers the following advantages: By incorporating reflective strips and equipping the working equipment with a rotating mechanism, a swing arm, and two laser rangefinders mounted on the swing arm, the rotating mechanism is controlled to adjust the swing arm's direction in real time. This ensures that the difference between the measurements from the two laser rangefinders is equal to a first preset value, guaranteeing that the laser emitted by the laser rangefinders is always perpendicular to the reflective strips. Consequently, the measured values ​​from the laser rangefinders can be directly compared with the nominal distance, and the deviation value allows for directional adjustment of the working equipment, enabling it to travel along a preset straight line. Firstly, the cost of this invention is significantly lower than that of lidar and high-end vision systems. Secondly, laser ranging exhibits strong resistance to ambient light interference, high measurement accuracy, and fast response; the reference reflective strip's position is fixed and clearly defined, unaffected by complex scenarios such as crop growth status and shadow changes, resulting in navigation stability far exceeding that of vision systems. Thirdly, the reflective strips can be flexibly laid out according to the structure of different greenhouses and the type of working ridges, serving as permanent facilities or temporarily deployed before operation, demonstrating strong adaptability. Fourth, it simplifies the complex spatial positioning problem into a tracking and control problem for a single lateral distance, reducing the computing power requirements of the controller and allowing for the use of low-cost controllers, which facilitates industrialization. Fifth, it fundamentally overcomes the limitation that facility agriculture cannot use satellite navigation, providing a reliable and practical navigation foundation for the fully automated operation of sowing, transplanting, management, and transportation in greenhouses. Attached Figure Description

[0038] Figure 1 A schematic diagram of the operating equipment;

[0039] Figure 2 This is a schematic diagram of the equipment operating inside the shed.

[0040] In the diagram, 1. Operating equipment; 2. Laser; 3. Reflective strip; 4. Controller; 5. Drive wheel; 6. Greenhouse; 7. Driven wheel; 8. Rotary seed metering device; 9. Lifting mechanism; 10. Laser rangefinder; 11. Rotating mechanism; 12. Swing arm; 13. Support column. Detailed Implementation

[0041] Hereinafter, embodiments will be described with reference to the accompanying drawings.

[0042] See Figures 1-2 This invention discloses a navigation system for greenhouses, used to navigate working equipment 1 inside the greenhouse. Working equipment 1 can be a seeder, fertilizer applicator, sprayer, or transport vehicle, etc. When working on a specific work ridge, working equipment 1 only needs to travel in a straight line along the ridge to complete the work on that ridge. After working equipment 1 completes the work on that ridge, it can be manually moved to another work ridge and then continue to travel in a straight line to perform work.

[0043] The greenhouse navigation system includes reflective strips 3, which are set parallel to the working ridges. Figure 1 The reflective strip 3 is located on the side wall of the shed. It also includes a rotating mechanism 11, which is mounted on the working equipment 1. The rotating mechanism 11 has a swing arm 12 mounted on it, which can drive the swing arm 12 to rotate around a vertical axis (here, the vertical axis refers to the direction perpendicular to the plane of travel of the working equipment). Two laser rangefinders 10 are mounted on the swing arm 12, spaced apart in a direction other than the vertical axis, and the laser emission directions of the two laser rangefinders 10 are parallel. The laser rangefinders 10 are used to measure the distance to the reflective strip 3.

[0044] It also includes a controller 4, which can be a microcontroller, an embedded industrial computer, or a programmable logic controller (PLC). The controller 4 controls the rotation of the rotating mechanism 11 to adjust the orientation of the swing arm 12, ensuring that the difference between the measured values ​​of the two laser rangefinders 10 always tends towards a first preset value; the first preset value is the distance between the two laser rangefinders 10 along the laser emission direction. This ensures that the lasers emitted by the two laser rangefinders 10 are always perpendicular to the reflective strip 3. In other words, when the working equipment 1 turns and its orientation is not parallel to the reflective strip 3, the controller 4 will control the rotating mechanism 11 to rotate the swing arm 12, thus ensuring that the lasers emitted by the two laser rangefinders 10 are always perpendicular to the reflective strip 3.

[0045] The controller 4 also adjusts the travel direction of the working equipment 1 based on the deviation between the measured value of the laser rangefinder 10 and the second preset value, so that the working equipment travels in a straight line. The second preset value is the nominal distance between one laser rangefinder 10 and the reflective strip 3 when the working equipment 1 is working along the working ridge. A nominal distance needs to be set in advance for each working ridge. When the measured value of the laser rangefinder 10 is this nominal distance, the working equipment is exactly in the accurate working position. Either of the two laser rangefinders 10 can be used to preset the nominal distance. When the working equipment 1 is working, the controller 4 only needs to adjust the travel direction of the working equipment based on the deviation between the measured value of the laser rangefinder 10 and the second preset value. Simply put, the controller 4 obtains the measured value of the laser rangefinder 10 at a certain sampling frequency, compares it with the second preset value, calculates the deviation between the two, and when there is a deviation between the measured value of the laser rangefinder 10 and the second preset value, it indicates that the working equipment 1 has deviated from the working ridge. The controller 4 adjusts the travel direction of the working equipment 1 in real time so that the deviation approaches 0 again. In this way, the actual distance between the laser rangefinder 10 and the reflective strip 3 can be maintained near the nominal distance, thereby enabling the working equipment 1 to travel in a straight line with high precision and complete the operation.

[0046] This invention utilizes reflective strips and incorporates a rotating mechanism, a swing arm, and two laser rangefinders on the operating equipment. By controlling the rotating mechanism to adjust the swing arm's direction in real time, the difference between the measurements from the two laser rangefinders is set to a first preset value. This ensures that the laser emitted by the laser rangefinders is always perpendicular to the reflective strip, allowing direct comparison between the measured values ​​and the nominal distance. The deviation value is used to adjust the direction of the operating equipment, ensuring it travels along a preset straight line. Firstly, the cost of this invention is significantly lower than that of lidar and high-end vision systems. Secondly, laser ranging offers strong resistance to ambient light interference, high measurement accuracy, and fast response; the reference reflective strip's position is fixed and clear, unaffected by complex scenarios such as crop growth status and shadow changes, resulting in navigation stability far exceeding that of vision systems. Thirdly, the reflective strips can be flexibly laid out according to different greenhouse structures and operating ridge types, serving as permanent facilities or temporarily deployed before operation, demonstrating strong adaptability. Fourthly, it simplifies the complex spatial positioning problem into a tracking and control problem of a single lateral distance, reducing the computational requirements of the controller and allowing for implementation with a low-cost controller, facilitating industrialization. Fifth, it fundamentally breaks through the limitation that facility agriculture cannot use satellite navigation, providing a reliable and practical navigation foundation for the entire process of automated operation such as sowing, transplanting, management and transportation in greenhouses.

[0047] The reflective strips 3 can be provided in twos, symmetrically installed on both sides of the shed 6, or only one can be provided. When there are two reflective strips 3, the working equipment 1 uses one of the reflective strips 3 as a reference for navigation when it is moving forward, and uses the other reflective strip 3 as a reference for navigation when it is turning around and moving backward.

[0048] When there is one reflective strip 3, when the working equipment 1 turns around and travels backward, the rotating mechanism 11 rotates 180 degrees so that the laser rangefinder 10 can still illuminate the reflective strip 3 perpendicularly.

[0049] Optionally, the first preset value is preferably set to 0, see [link to relevant documentation]. Figure 1 , Figure 1The diagram shows two laser rangefinders 10 spaced apart only in a direction perpendicular to the laser emission direction and perpendicular to the vertical axis. In this case, the first preset value is 0. One specific implementation is as follows: the swing arm 12 extends in a straight line, the two laser rangefinders 10 are aligned with each other along the extension direction of the swing arm 12, and the laser emission direction is perpendicular to the extension direction of the swing arm 12. In this case, the controller 4 adjusts the orientation of the swing arm 12 by controlling the rotation mechanism 11 as follows: The controller acquires the distances Lt1 and Lt2 between the two laser rangefinders 10 and the reflective strip 3 in real time, calculates the difference Δ(k) = Lt1(k) - Lt2(k), and when Δ(k) > 0 or Δ(k) < 0, the controller 4 controls the rotation mechanism 11 to rotate the swing arm 12 so that Δ(k) approaches 0, ensuring that the lasers emitted by the two laser rangefinders 10 are perpendicular to the reflective strip 3. When setting the second preset value, i.e., the nominal distance, any laser rangefinder 10 can be used for calibration, and the measured values ​​of the two laser rangefinders 10 will be the same. In specific control, the controller 4 can first calculate the average value of the measured values ​​of the two laser rangefinders 10, and then adjust the travel direction of the working equipment based on the deviation between the average value and the second preset value.

[0050] During the movement of the working equipment 1, the rotating mechanism 11 will dynamically adjust the orientation of the swing arm 12 so that the swing arm 12 is always parallel to the reflective strip 3. The swing arm 12 will also be slightly tilted during this process. At this time, the average value of the measurement values ​​of the two laser rangefinders 10 is used as the adjustment basis, and the adjustment accuracy is higher.

[0051] Optionally, the controller 4 may employ a PID control algorithm, a fuzzy control algorithm, or a sliding mode variable structure control algorithm to calculate the steering control quantity based on the deviation between the measured value of the laser rangefinder and the second preset value; and adjust the travel direction of the working equipment based on the steering control quantity.

[0052] Optionally, when the first preset value is 0, the controller calculates the steering control quantity based on the PID control algorithm, which may specifically include:

[0053] The controller calculates the deviation value: e(k) = Lt(k) - L0, Lt(k) = (Lt1(k) + Lt2(k)) / 2; where Lt(k) is the average value of the measurements of the two laser rangefinders at time k, Lt1(k) and Lt2(k) are the measurements of the two laser rangefinders at time k, e(k) is the deviation value at time k, and L0 is the second preset value;

[0054] An incremental PID control algorithm is adopted. Based on the current and historical deviation values, the steering control quantity to be applied in the current control cycle is calculated as follows: Δω(k)=Kp*[e(k)-e(k-1)]+Ki*e(k)+Kd*[e(k)-2e(k-1)+e(k-2)], where Δω(k) is the steering control quantity to be applied in the current control cycle, and Kp, Ki and Kd are the pre-set proportional, integral and derivative coefficients, respectively.

[0055] Optionally, the working device 1 includes two drive wheels 5 driven by independent servo motors; the controller 4 calculates the speed difference between the two drive wheels 5 based on the steering control amount Δω(k), and controls the rotation of the two drive wheels 5 based on the speed difference so that the working device 1 can adjust its direction of travel.

[0056] Specifically, the operating equipment 1 adopts a four-wheel differential steering chassis, including two drive wheels 5, which are the front wheels and are driven by two independent servo motors. Steering is achieved through the differential speed of the two drive wheels 5. It also includes two rear driven wheels 7, which can be omnidirectional wheels. The controller 4 can receive data from the laser rangefinder 10 via a serial port and control the servo motors of the two drive wheels 5 via a CAN bus. A rotating seed metering device 8 is installed in the middle of the operating equipment via a lifting mechanism 9. The lifting mechanism 9 can be driven by an electric push rod, which can lower during seeding operations and raise when not in operation.

[0057] Optionally, the reflective strip 3 is installed at the ventilation opening on the side wall of the shed 6. The reflective strip 3 is connected to the roller shutter mechanism. The roller shutter mechanism rolls up the reflective strip 3 when ventilating and unfolds the reflective strip 3 when the operating equipment 1 is in operation.

[0058] Optionally, controller 4 is also configured with a temporary occlusion strategy:

[0059] When the laser rangefinder 10 signal is abnormal, such as when the signal of at least one laser rangefinder 10 is lost or the value changes abruptly, the controller 4 determines it as a temporary obstruction and controls the work equipment 1 to continue traveling in the original direction for a first preset distance or a first preset time period. For example, when the laser rangefinder 10 fails to receive a valid reflected signal for 3 to 5 consecutive sampling cycles, or for example, when the measured value changes abruptly from 2 meters to 0.5 meters, the controller 4 determines it as a temporary obstruction. When the laser rangefinder 10 signal returns to normal, the controller continues to control the work equipment 1 to move based on the measured value of the laser rangefinder 10.

[0060] If the signal of the laser rangefinder 10 fails to return to normal at the first preset distance or during the first preset time period, the system is deemed abnormal, and the controller 4 controls the operating equipment 1 to stop operating and issues a fault alarm signal.

[0061] Some support columns 13 inside the shed may temporarily block the laser, preventing the laser from illuminating the reflective strip 3. This can cause the laser range sensor 10 to lose its signal or the measured value to change abruptly. Adding a temporary blocking strategy can solve this problem. The first preset distance can be 0.2 to 0.5 meters, and the first preset time can be preset according to the travel speed of the working equipment 1. The first preset time or the first preset distance is sufficient for the working equipment 1 to show the column blocking area.

[0062] Optionally, the controller 4 is also set with a first travel distance. After the working equipment 1 has traveled the first travel distance, the controller 4 controls the working equipment 1 to stop traveling and issues a prompt message indicating that it has reached the end of the working ridge.

[0063] Before each operation on a single work ridge, the operating device 1 sets a first travel distance for the controller 4, which is the operating distance of the operating device 1 on that work ridge. When the accumulated travel distance of the operating device 1 reaches this first travel distance, it indicates that the operating device 1 has reached the designated location at the end of the work ridge. The controller 4 will then control the operating device 1 to issue a prompt message, such as a prompt sound or a prompt light. At this point, manual intervention is required to move the operating device 1 to the next work ridge for operation.

[0064] The present invention also provides a navigation method for navigating working equipment inside a shed, comprising the following steps:

[0065] S1: Lay reflective strips along the direction of the working rows inside the greenhouse;

[0066] S2: Set a second preset value between the laser rangefinder and the reflective strip. There are two laser rangefinders, which are mounted on a swing arm. The swing arm is mounted on the working equipment through a rotating mechanism. The laser emission direction of the two laser rangefinders is perpendicular to the swing arm, and the distance between the two laser rangefinders in the laser emission direction is 0.

[0067] S3: When the operating equipment is in operation, it acquires the measured values ​​of the two laser ranging sensors in real time;

[0068] S4: Calculate the difference between the measured values ​​of the two laser rangefinders, and control the rotating mechanism to rotate according to the difference, so that the difference approaches zero, so that the laser emitted by the laser rangefinder is perpendicular to the reflective strip;

[0069] S5: Calculate the average of the two measured values, and the deviation of the average value from the second preset value;

[0070] S6: Calculate the steering control amount using a control algorithm based on the aforementioned deviation;

[0071] S7: Control the direction of travel of the working equipment based on the steering control amount.

[0072] Optionally, in step S2, the working equipment is manually controlled to walk along the desired path once, and the controller records a stable distance value during the teaching process and sets it as the second preset value.

Claims

1. A navigation system for greenhouses, characterized in that, This includes reflective strips installed inside the greenhouse, which are arranged parallel to the working ridges; It also includes a rotating mechanism for mounting on the work equipment, which is rotatable about a vertical axis. The rotating mechanism is equipped with a swing arm, and the swing arm has two laser range sensors spaced apart in a direction other than the vertical axis. The laser emission directions of the two laser range sensors are parallel. The laser range sensors are used to measure the distance to the reflective strip. It also includes a controller for controlling the rotation of the rotating mechanism to adjust the orientation of the swing arm so that the difference between the measured values ​​of the two laser rangefinders always tends to a first preset value; the controller also adjusts the travel direction of the working equipment based on the deviation between the measured values ​​of the laser rangefinders and a second preset value so that the working equipment travels in a straight line; the first preset value is the distance between the two laser rangefinders along the laser emission direction; the second preset value is the nominal distance between one of the laser rangefinders and the reflective strip when the working equipment is working along the working ridge.

2. The greenhouse navigation system as described in claim 1, characterized in that, The first preset value is 0. The controller further adjusts the travel direction of the working equipment based on the deviation between the measured value of the laser rangefinder and the second preset value, specifically including: The controller calculates the average of the measurements from the two laser rangefinders; The controller adjusts the direction of travel of the working equipment based on the deviation between the average value and the second preset value.

3. The greenhouse navigation system as described in claim 1, characterized in that, The controller also adjusts the travel direction of the working equipment based on the deviation between the measured value of the laser rangefinder and the second preset value, specifically including: The controller employs a PID control algorithm, a fuzzy control algorithm, or a sliding mode variable structure control algorithm to calculate a steering control quantity based on the deviation between the measured value of the laser rangefinder and a second preset value; and adjusts the travel direction of the working equipment based on the steering control quantity.

4. The greenhouse navigation system as described in claim 3, characterized in that, The first preset value is 0. The controller calculates the steering control quantity based on the PID control algorithm, specifically including: The controller calculates the deviation value: e(k) = Lt(k) - L0, Lt(k) = (Lt1(k) + Lt2(k)) / 2; where Lt(k) is the average value of the measurements of the two laser ranging sensors at time k, Lt1(k) and Lt2(k) are the measurements of the two laser ranging sensors at time k, e(k) is the deviation value at time k, and L0 is the second preset value; An incremental PID control algorithm is adopted. Based on the current and historical deviation values, the steering control quantity to be applied in the current control cycle is calculated as follows: Δω(k)=Kp*[e(k)-e(k-1)]+Ki*e(k)+Kd*[e(k)-2e(k-1)+e(k-2)], where Δω(k) is the steering control quantity to be applied in the current control cycle, and Kp, Ki and Kd are the pre-set proportional, integral and derivative coefficients, respectively.

5. The greenhouse navigation system as described in claim 4, characterized in that, The working device includes two drive wheels, each driven by an independent servo motor. Adjusting the direction of travel of the working equipment based on the steering control amount specifically includes: The controller calculates the speed difference between the two drive wheels based on the steering control quantity, and controls the rotation of the two drive wheels based on the speed difference.

6. The greenhouse navigation system as described in claim 1, characterized in that, The reflective strip is installed at the ventilation opening on the side wall of the shed. The reflective strip is connected to the roller shutter mechanism. The roller shutter mechanism rolls up the reflective strip when ventilation is needed and unfolds the reflective strip when the operating equipment is in operation.

7. The greenhouse navigation system as described in claim 1, characterized in that, The controller is also equipped with a temporary occlusion strategy: When the laser ranging sensor signal is abnormal, the controller determines it as a temporary obstruction and controls the working equipment to continue traveling in the original direction for a first preset distance or a first preset time period. When the laser rangefinder sensor signal returns to normal, the operation equipment continues to move based on the measured value of the laser rangefinder sensor. If the laser ranging sensor fails to restore the signal to normal after the work equipment has traveled a first preset distance or a first preset time period, the system is deemed abnormal, and the controller controls the work equipment to stop operating and issues a fault alarm signal.

8. The greenhouse navigation system as described in claim 7, characterized in that, The controller is also set with a first travel distance. After the working equipment has traveled the first travel distance, the controller controls the working equipment to stop and issues a prompt message indicating that it has reached the end of the working ridge.

9. A navigation method for navigating operating equipment inside a shed, characterized in that, Includes the following steps: S1: Lay reflective strips along the direction of the working rows inside the greenhouse; S2: Set a second preset value between the laser rangefinder and the reflective strip. There are two laser rangefinders, which are mounted on a swing arm. The swing arm is mounted on the working equipment through a rotating mechanism. The laser emission direction of the two laser rangefinders is perpendicular to the swing arm, and the distance between the two laser rangefinders in the laser emission direction is 0. S3: When the operating equipment is in operation, it acquires the measured values ​​of the two laser ranging sensors in real time; S4: Calculate the difference between the measured values ​​of the two laser rangefinders, and control the rotating mechanism to rotate according to the difference, so that the difference approaches zero, so that the laser emitted by the laser rangefinder is perpendicular to the reflective strip; S5: Calculate the average of the two measured values, and the deviation of the average value from the second preset value; S6: Calculate the steering control amount using a control algorithm based on the aforementioned deviation; S7: Control the direction of travel of the working equipment based on the steering control amount.

10. The navigation method as described in claim 9, characterized in that, In step S2, the working equipment is manually controlled to walk along the desired path once, and the controller records a stable distance value during the teaching process and sets it as the second preset value.

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