Seeder ground speed radar accurate speed measurement method and system based on speed measurement angle real-time correction

Abstract

The invention belongs to but not limited to the technical field of speed measurement systems, and discloses a seeding machine ground speed radar accurate speed measurement method and system based on speed measurement angle real-time correction, and the system comprises a speed monitoring module and a control unit, the speed monitoring module comprises a ground speed radar and an inertial measurement element, the control unit obtains the inclination angle of the seeder from the speed data obtained by the radar and the inertial measurement element, corrects and filters the speed measurement result to obtain the accurate advancing speed of the seeder, and then adjusts the rotating speed of the motor according to the accurate speed. According to the method, recursive average filtering is used for filtering a radar speed measurement result, so that high-frequency noise and random errors are effectively suppressed; data of the gyroscope and data of the accelerometer are combined through a quaternion attitude resolving algorithm, long-term accumulative errors are corrected, and accurate tracking of complex dynamic attitudes in the advancing process of the seeder is achieved; and calculating a correction coefficient according to the radar speed measurement result and the angle measurement result by using a correction formula, and correcting the radar speed measurement result by using the correction coefficient to obtain a high-precision radar speed measurement result.

Description

Technical Field

[0001] The present invention belongs to the technical field of intelligent agricultural machinery and equipment, and relates to a method and system for accurately measuring the speed of a planter using a ground speed radar based on real-time correction of speed measurement angle compensation. Background Art

[0002] Seeding is a crucial step in agricultural production. With socioeconomic development and advancements in agricultural machinery, traditional manual sowing has gradually shifted to seeding with seeders, significantly improving efficiency and reducing labor intensity. Speed-dependent seeding technology is a key component in achieving high-performance sowing. Specifically, it dynamically adjusts the seeding speed of the seeder based on the seeder's real-time speed, ensuring uniform seed distribution according to agronomic requirements.

[0003] Traditional seed drills measure speed using a ground wheel and transmit torque through a mechanical transmission system to drive the seed meter, achieving speed-dependent seeding. However, these systems suffer from issues such as ground wheel slippage, distortion of ground wheel speed measurement due to soil adhesion and clogging, and difficulty in adjusting the seeding rate steplessly. These issues do not meet the production requirements for intelligent, high-performance seeding, leading to the development of intelligent electric seeding. Accurately determining the real-time speed of the seed drill is crucial for intelligent electric seeding. Currently, there are two main methods for measuring seed drill speed: wheel rotation speed, such as using Hall effect sensors and encoders; and vehicle body speed, such as using Beidou satellite positioning modules and radar. Hall effect sensors and encoders are typically mounted coaxially with the tractor's wheel or ground wheel axle. These sensors measure the number of wheel rotations per unit time to determine the seed drill's travel speed. While these speed measurements offer high real-time performance, they can be susceptible to slippage, blockage, and stalls during operation. Satellite positioning systems analyze telegrams to determine the tractor's position and speed, but are susceptible to satellite signal strength and exhibit a certain degree of lag. Microwave radar speed measurement offers high real-time performance, but its accuracy is highly sensitive to the radar's mounting angle.

[0004] For example, Chinese patent application CN115061129A, "Intelligent Control Method for Precision Seeders Based on Doppler Radar Speed ​​Measurement," uses Doppler radar to measure the machine's operating speed. The radar is fixed at a 55° angle to the ground, and the speed of the seed meter motor is controlled directly based on the speed measurement. This invention ignores the impact of actual field operation, such as planter vibrations and terrain changes, on the radar's angle to the ground, which in turn affects the stability and accuracy of speed measurement.

[0005] For example, in the Chinese patent "A radar speed measurement inertial compensation method and a radar speed measurement system with inertial compensation" with publication number CN116087898A, the vehicle's tilt angle is calculated using the acceleration obtained in real time by the inertial measurement unit, and the compensation value of the vehicle speed at this time is calculated using this angle, thereby obtaining a more accurate vehicle speed after compensation. This invention is mainly used in rail transportation equipment, stabilizes high-speed working environments, and uses empirical correction coefficients. In the complex terrain and low-speed operation of agricultural field operations, accelerometers are easily affected by linear acceleration and interference from external factors such as vibration and temperature changes, and their measurement accuracy will be affected in scenarios with rapid dynamic changes.

[0006] In view of the above analysis, the technical problem that urgently needs to be solved in the existing technology is: when the precision seeder is operating, the vibration of the machine causes the change in the radar antenna illumination angle to affect the radar speed measurement results. Summary of the Invention

[0007] In response to the problems existing in the prior art, the present invention provides a method and system for accurately measuring the speed of a planter using a ground speed radar based on real-time correction of the speed measurement angle. The specific technical solution is as follows:

[0008] A method and system for accurately measuring the speed of a planter using a ground speed radar based on real-time correction of the speed measurement angle is presented. The speed measurement method uses an inertial measurement element to measure the planter's real-time tilt angle, corrects the radar's speed measurement results, and performs recursive averaging filtering to ultimately obtain a highly accurate real-time planter speed.

[0009] A method and system for accurately measuring the speed of a seed drill using a ground speed radar based on real-time correction of speed measurement angles. The speed measurement system includes a seed meter driven by a motor, a speed monitoring module, and a control unit for implementing the accurate speed measurement method. The speed monitoring module includes a ground speed radar and an inertial measurement element. The control unit calculates a correction coefficient based on speed data obtained by the radar and the seed drill's inclination angle obtained by the inertial measurement element, corrects the radar speed measurement result, then performs recursive averaging filtering on the corrected speed measurement result to obtain the seed drill's accurate speed. Finally, the motor speed is adjusted based on the accurate seed drill's speed. The speed measurement system also includes a display screen.

[0010] The speed measurement system comprises the following steps:

[0011] Step 1: obtain real-time speed raw data from the ground speed radar and obtain real-time planter tilt angle from the inertial measurement unit;

[0012] Step 2: Calculate the corresponding correction coefficient using the correction formula based on the speed and angle data to obtain the corrected accurate speed and adjust the speed of the seed metering device motor;

[0013] Step 3: Send the speed and sowing status to the display screen in real time for visual display, and receive data from the display screen to adjust the sowing status.

[0014] Furthermore, the core components of the inertial measurement element are a gyroscope and an accelerometer. The gyroscope can measure the angular velocity of three axes, and the accelerometer can measure the acceleration of three axes. In addition to providing the 16-bit ADC signal acquisition function of the three-axis gyroscope and three-axis accelerometer sensors, the inertial measurement element also integrates a digital low-pass filter and a digital motion processor, which can directly output quaternion data after low-pass filtering and quaternion attitude solution; the control unit converts the quaternion into Euler angles to obtain the accurate pitch angle, that is, the angle between the planter and the horizontal.

[0015] Furthermore, a ground speed radar correction database and correction formula are constructed

[0016] The radar speed measurement result is divided by the reference speed to obtain the correction coefficient, as shown in the following formula:

[0017]

[0018] Where v is the radar speed measurement result, v0 is the reference speed, and k is the correction coefficient;

[0019] A database of correction coefficients for a wide range of situations is constructed. Using speed measurement results and radar-to-ground angle as independent variables, and the correction coefficient as the dependent variable, a quadratic polynomial is fitted to obtain a correction formula. This correction formula is then input into the control unit. In actual use, the control unit calculates the correction coefficient based on the radar speed measurement results and angle measurements. This correction coefficient is then used to correct the radar speed measurement results, resulting in highly accurate speed data.

[0020] Furthermore, recursive averaging filtering is used to filter the radar speed measurement results. Recursive averaging filtering refers to taking the average of the latest measurement result and the first N-1 measurement results as the latest measurement result. The formula is as follows:

[0021]

[0022] Where y[n] is the output value after the nth filtering; x[nk] is the original data value at the past n sampling moments; and N is the window size of the average value, that is, the number of historical data points involved in the calculation.

[0023] The specific process of implementing recursive averaging filtering is to set an array as the radar speed measurement data storage in the control unit. The length of the array is N. The recursive averaging filtering is implemented using the array. The process is as follows:

[0024] Get the new radar speed measurement result and move each bit of the array forward one position;

[0025] Save the latest radar speed measurement results to the end of the array;

[0026] Calculate the average value and perform arithmetic average on the N-bit data in the array;

[0027] Output filtering results.

[0028] Furthermore, PWM modulation is used to achieve speed regulation of the brushless DC motor. By adjusting the PWM duty cycle, the seeding speed of the seed meter can be effectively controlled to achieve precise sowing. The size of the PWM signal is calculated and dynamically adjusted by the controller based on the real-time acquired and corrected filtered radar speed measurement data and the preset agronomic requirements.

[0029] Another object of the present invention is to provide a precise speed measurement device for a seed drill, which includes a precise speed measurement method and system for a ground speed radar of a seed drill based on real-time correction of the speed measurement angle. The precise speed measurement device includes a seed meter driven by a motor, a speed monitoring module, a display screen, and a control unit for implementing the precise speed measurement method; the speed monitoring module includes a ground speed radar and an inertial measurement element, the ground speed radar measures the real-time travel speed of the seed drill, and the inertial measurement element obtains the inclination angle of the seed drill; the control unit is a single-chip microcomputer, and the display screen is connected to the control unit; the display screen has a data input function and a data display function, which is used for manual input of the required operating parameters, such as starting the operation, theoretical plant spacing, speed measurement settings, etc., and can also display the current speed measurement results and parameters such as the sowing amount.

[0030] Furthermore, the ground speed radar and inertial measurement element are installed on a mounting bracket, which is fixed on the vertically downward side of the seed drill to ensure that the radar faces the ground without obstruction and the upper end face of the mounting bracket is installed horizontally. At this time, the angle between the mounting surface of the radar and the horizontal plane is a specific angle; the mounting bracket reserves a mounting hole for the radar, and bolts and nuts are used to pass through the radar and the mounting bracket to tighten and fix them; a mounting slot and mounting hole are reserved for the inertial measurement element, and the inertial measurement element is placed in the mounting slot and tightened and fixed with screws.

[0031] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0032] First, the present invention corrects the radar speed measurement results according to the real-time posture of the seeder, and uses recursive average filtering to effectively suppress high-frequency noise and random errors, making the results more accurate and smoother, which is beneficial to the subsequent control of the seed metering device speed.

[0033] The present invention combines the data of the gyroscope and accelerometer through a quaternion attitude solution algorithm, uses the high dynamic response characteristics of the gyroscope to perform short-term attitude prediction, and uses the information of the accelerometer to correct the long-term accumulated error, thereby achieving accurate tracking of the complex dynamic attitude of the seed drill during its movement.

[0034] The present invention uses a correction formula to calculate a correction coefficient according to the radar speed measurement result and the seed drill posture measurement result during the actual radar speed measurement process, and uses the correction coefficient to correct the radar speed measurement result to obtain a high-precision radar speed measurement result.

[0035] Existing seed drill speed measurement simply uses radar speed measurement, but does not take into account that during the operation of the seed drill, complex terrain, mechanical vibration and changes in operating speed will cause the ground speed radar to change, resulting in deviations in the radar speed measurement results, making it difficult to meet the precise speed requirements of precision seeding.

[0036] The difficulty in solving the above problems lies in the fact that during the actual sowing process, the posture information and speed information of the seeder change dynamically. How to quickly correct the radar speed measurement results while obtaining posture data in real time? The complexity of the farmland environment requires the speed measurement system to have strong robustness and anti-interference capabilities. In view of the measurement error of the radar at different ground angles and speeds, it is necessary to fit a large amount of experimental data to obtain the correction formula, while ensuring that the formula is applicable to various terrains and operating conditions.

[0037] The present invention uses an inertial measurement unit (IMU) to obtain the planter's attitude information in real time. The IMU's built-in digital motion processor, which combines a gyroscope and accelerometer, can output the planter's attitude information at high frequency, providing basic data for correcting radar speed measurement results. During the research and development phase, the present invention experimentally obtained radar speed data at different angles and speeds, using the encoder speed measurement results as the actual speed reference value. A correction formula was established through a fitting algorithm. Recursive averaging filtering was performed on the radar speed measurement results to reduce fluctuations and errors in the speed measurement results. The filter window size was also adjusted to adapt to various terrains and operating conditions.

[0038] The relevant codes such as correction formula, recursive filtering, inertial measurement element data reading, human-computer interaction, etc. are written into the control unit. In the actual sowing process, the present invention reads the radar speed measurement results and the seed drill posture information, and dynamically corrects the radar speed measurement results by calculating the correction coefficient based on the correction formula and real-time posture information and speed measurement data, and outputs high-precision real-time speed information. The radar speed measurement results, after correction and after filtering are as follows Figure 6 , effectively reducing the error and volatility of radar speed measurement. After correction and filtering, the planter's speed is reliable, with an average relative error of less than 2% and a maximum relative error of less than 10%.

[0039] The present invention utilizes a precision speed measurement method and system for a planter ground speed radar with real-time correction of the speed measurement angle. This method and system can obtain the planter's travel speed in real time with higher accuracy and can adapt to complex environments such as slopes and rugged terrain. The technical solution of the present invention is simple and efficient, easily integrated into existing agricultural machinery, and can provide accurate speed information for speed-dependent planter machinery, effectively ensuring its seeding uniformity and reducing the problems of missed or reseeded seeds due to speed fluctuations, significantly improving operational quality and agricultural production efficiency. Furthermore, the present invention can be extended to precision-controlled equipment such as rice transplanters, fertilizer spreaders, and sprayers that require accurate motion speed information.

[0040] Second, the present invention uses a precise speed measurement method and system for a planter ground speed radar based on real-time correction of the speed measurement angle, which can accurately obtain the real-time speed data of the planter during operation at a low cost. The technical solution of the present invention is simple and efficient, and can be easily integrated into existing agricultural machinery. The low-cost speed measurement solution is conducive to reducing the price of agricultural machinery, has extremely high market demand and commercialization potential, and can be needed by various agricultural machinery manufacturers. It can be applied to large-scale sowing agricultural machinery to provide accurate speed information support for sowing operations, which is conducive to precision sowing operations, avoiding over-sowing or under-sowing, improving crop growth conditions and increasing yields. At the same time, the invention can be extended to variable fertilization, spraying and other operations of ground machinery to reduce the amount of fertilizers and pesticides used and the impact on the environment.

[0041] Aiming at the operation of a seed drill, the present invention designs a low-cost radar precision speed measurement system with angle compensation. The radar speed measurement results are corrected in real time according to the radar-to-ground angle during the seed drill movement, effectively reducing the speed measurement error in complex terrain.

[0042] The radar III speed sensor produced by the US-based Diqiang Company boasts a wide speed measurement range and precise results. Through on-site calibration, the sensor can achieve a speed error of 1%-3%. Domestically, Hubei Yongxiang uses radar to measure operating speed and adjust seeding rates in real time, achieving seeding accuracy exceeding 98%. While both technologies offer high speed measurement accuracy, their high price points hinder market acceptance. This invention achieves low-cost, high-precision speed measurement, effectively filling a technological gap in high-precision speed measurement for agricultural seeders both domestically and internationally.

[0043] The development of precision agriculture is placing higher demands on the real-time control and operational accuracy of agricultural machinery. However, the industry currently lacks low-cost solutions that can provide high-precision, real-time speed measurement for agricultural machinery. Traditional agricultural machinery speed measurement often relies on single sensor solutions such as ground speed radar, encoders, and Beidou speed measurement. These solutions suffer from weak anti-interference capabilities and inability to adapt to complex environments. The technical solution of this invention fills this gap, enabling low-cost radar-based, accurate speed measurement of seed drills during operation, providing technical support for the upgrade of precision agriculture equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a diagram of a system structure for accurately measuring the speed of a planter using a ground speed radar based on real-time correction of the speed measurement angle, provided by an embodiment of the present invention;

[0045] Figure 2 This is a diagram of the installation structure of a planter ground speed radar accurate speed measurement method and system based on real-time correction of speed measurement angle provided by an embodiment of the present invention;

[0046] Figure 3 This is a flowchart of a method and system for accurately measuring the speed of a planter using a ground speed radar based on real-time correction of the speed measurement angle provided by an embodiment of the present invention;

[0047] Figure 4 This is a diagram of a dynamic working process of a planter ground speed radar accurate speed measurement method based on real-time correction of speed measurement angle provided by an embodiment of the present invention;

[0048] Figure 5 1 is a diagram showing the speed measurement results and fitting results of the radar at different angles and speeds provided by an embodiment of the present invention;

[0049] Figure 6 This is a radar effect diagram provided by an embodiment of the present invention;

[0050] In the figure: 1. Inertial measurement unit; 2. Ground speed radar; 3. Control unit; 4. Seeder motor; 5. Display screen; 6. Nut; 7. Bolt; 8. Mounting bracket; 9. Screw. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0052] like Figure 1 As shown, an embodiment of the present invention provides a method and system for accurately measuring the speed of a planter using a ground speed radar based on real-time correction of a speed measurement angle. The speed measurement system includes a seed meter driven by a motor, a speed monitoring module, and a control unit for implementing the accurate speed measurement method; the speed monitoring module includes a ground speed radar and an inertial measurement element; the control unit calculates a correction coefficient based on the speed data obtained by the radar and the planter inclination angle obtained by the inertial measurement element, corrects the radar speed measurement result, and then performs recursive averaging filtering on the corrected speed measurement result to obtain the accurate speed of the planter, and finally adjusts the speed of the motor according to the accurate speed of the planter; the speed measurement system also includes a display screen.

[0053] The core components of the inertial measurement unit are the gyroscope and accelerometer. The gyroscope can measure the angular velocity of the three axes, and the accelerometer can measure the acceleration of the three axes. In addition to providing signal acquisition functions for the three-axis gyroscope and three-axis accelerometer sensors, the inertial measurement unit also integrates a digital low-pass filter and a digital motion processor, which can directly output quaternion data after low-pass filtering and quaternion attitude solution. Converting the quaternion to Euler angles can obtain accurate roll, pitch, and yaw angles. The specific formula is as follows:

[0054]

[0055] θ=arcsin(-2(q1q3-q0q2))

[0056]

[0057] Among them: q1, q2, q3, q4 are quaternions, φ is the roll angle, θ is the pitch angle, ψ is the yaw angle

[0058] The present invention uses the quaternion output of a digital motion processor built into an inertial measurement unit to calculate the change in the planter's angle relative to the ground during travel. This digital motion processor employs a quaternion attitude solution algorithm that combines data from a gyroscope and an accelerometer to calculate the planter's attitude angle in three-dimensional space in real time through a fusion algorithm. This fusion method not only improves the accuracy of angle measurement but also effectively overcomes the drawback of a single sensor being susceptible to noise interference. Specifically, a gyroscope can provide high-precision angular velocity information, which can be integrated to obtain the attitude angle, but the accumulated error gradually increases over time. An accelerometer, on the other hand, can measure the components of gravity acceleration along three axes and calculate the attitude angle through inverse tangent calculation, but is not suitable for complex and changing working environments. The quaternion attitude solution algorithm cleverly combines the data from these two methods, utilizing the high dynamic response characteristics of the gyroscope for short-term attitude prediction while simultaneously using information from the accelerometer to correct for long-term accumulated errors, thus accurately tracking the complex dynamic attitude of the planter during travel.

[0059] In view of the fact that radar speed measurement results are greatly affected by changes in ground angle, a small vehicle speed measurement platform is used to simulate the speed and angle variation range of radar speed measurement when working in the field. Radar speed measurement is carried out on a flat road at different speeds and ground speed radar installation angles to obtain radar speed measurement results at different speeds and different ground angles. The correction coefficient is obtained by dividing the radar speed measurement result by the reference speed, as shown in the following formula:

[0060]

[0061] Where v is the radar speed measurement result, v0 is the reference speed, and k is the correction coefficient;

[0062] A database of correction coefficients for a large number of different situations is constructed. Using speed measurement results and radar-to-ground angles as independent variables and correction coefficients as dependent variables, a correction formula is obtained using polynomial fitting. This correction formula is written into a control unit, and used during actual radar speed measurement to calculate the correction coefficient based on the radar speed and angle measurements. The correction coefficient is then used to correct the radar speed measurement results, resulting in highly accurate radar speed measurement results.

[0063] Use recursive averaging filtering to filter the radar speed measurement results. When a planter is operating in the field, the vibration of the implement will cause high-frequency vibration and measurement errors in the radar speed measurement results, making them unsuitable for direct use in speed-dependent seeding systems. Recursive averaging filtering uses the average of the latest measurement result and the previous N-1 measurement results as the latest measurement result. The formula is as follows:

[0064]

[0065] Where y[n] is the output value after the nth filtering; x[nk] is the original data value at the past n sampling moments; and N is the window size of the average value, that is, the number of historical data points involved in the calculation.

[0066] After calculating the average value, the impact of short-term fluctuations or noise on the signal can be effectively reduced, making the output signal smoother and effectively reducing signal fluctuations and system noise. The advanced nature of recursive averaging filtering also lies in the ability to adjust the N value to adapt to different seeding operation environments. For example, when the N value is large, the number of measurement data involved in the average calculation increases, making the filtered signal smoother, reducing signal fluctuations and noise, and improving accuracy. However, this will reduce the signal's sensitivity to environmental changes and real-time performance, making it suitable for farmland with flat terrain and improving signal accuracy. A smaller N value has the opposite filtering effect, making it suitable for farmland with significantly undulating terrain and ensuring real-time performance.

[0067] Therefore, the present invention uses recursive averaging filtering to filter the radar speed measurement results, effectively suppressing high-frequency noise and random errors, making the results more accurate and smoother, and obtaining smooth radar speed measurement results, which is convenient for subsequent control of the seed metering device motor speed.

[0068] In the control unit, an array is set as the radar speed measurement data storage. The length of the array is N. The array is used to implement recursive averaging filtering. The process is as follows:

[0069] Get the new radar speed measurement result and move each bit of the array forward one position;

[0070] Save the latest radar speed measurement results to the end of the array;

[0071] Calculate the average value and perform arithmetic average on the N-bit data in the array;

[0072] Output filtering results.

[0073] PWM modulation is used to regulate the speed of the brushless DC motor. By adjusting the PWM duty cycle, the seed meter's seeding speed can be effectively controlled, achieving precise seeding. The controller calculates and dynamically adjusts the PWM signal based on real-time, filtered, and corrected radar velocity data, as well as preset agronomic requirements. This not only adapts to complex environmental changes in field operations, but also ensures uniformity and efficiency in seeding, improving operational quality.

[0074] System installation as Figure 2 As shown, the ground speed radar 2 and inertial measurement unit 1 are mounted on a mounting bracket 8, which is fixed to the vertical, downward-facing side of the planter. This ensures that the ground speed radar 2 faces the ground unobstructed, and the upper end of the mounting bracket 8 is horizontal. The mounting surface of the ground speed radar 2 forms a fixed angle with the horizontal plane. Specifically, the mounting bracket 8 has three mounting holes reserved for the ground speed radar 2, which are secured with bolts 7 and nuts 6 that pass through the radar and the mounting bracket 8. A mounting slot and mounting hole are reserved for the inertial measurement unit 1, which is placed in the mounting slot and secured with screws 9.

[0075] Connect as Figure 1 The precise speed measurement system has a seed meter motor 4, adopts air-feed sowing, and can perform sowing operations on multiple sowing rows at the same time. The control unit 3 is a single-chip microcomputer, and the display screen 9 is connected to the control unit 3; the display screen 9 has data input function and data display function, which is used for manual input of the required operating parameters, such as starting operation, theoretical plant spacing, speed measurement settings, etc. At the same time, the display screen 9 can display the current speed measurement results and parameters such as sowing amount.

[0076] The ground speed radar 2 and the inertial measurement unit 1 are both fixedly mounted on a mounting bracket 8, which is fixed to the vertically downward side of the planter to ensure that the ground speed radar 2 always faces the ground without obstruction. The upper end surface of the mounting bracket 8 is installed horizontally, so that the mounting surface of the ground speed radar 2 forms a fixed angle with the horizontal plane. Specifically, the mounting bracket 8 has three mounting holes reserved for the ground speed radar 2, and bolts 7 and nuts 6 are used to pass through the ground speed radar 2 and the mounting bracket 8 for fastening. For the inertial measurement unit 1, the mounting bracket 8 is designed with a dedicated mounting slot and mounting hole. After placing it in the mounting slot, it is then secured with screws 9.

[0077] The system's ground speed radar 2 collects real-time ground speed data as the planter moves forward, while the inertial measurement unit 1 uses its built-in three-axis gyroscope and three-axis accelerometer to measure the planter's tilt angle in different directions. Data from both sensors undergo analog-to-digital conversion and initial processing using a digital low-pass filter and digital motion processor, converting them into digital signals for subsequent data processing.

[0078] After receiving the speed data from the ground speed radar 2 and the tilt angle data output by the inertial measurement unit 1, the control unit 3 first calculates a correction coefficient based on the tilt angle data to perform angle compensation on the radar speed data. The compensated speed data is further processed using a recursive averaging filtering method, that is, the arithmetic average of the most recently collected speed data and several previously collected historical data is calculated to obtain an accurate speed measurement result.

[0079] The filtered and corrected speed data is used by the control unit 3 to adjust the speed of the seed meter motor 4 in real time. The speed control signal is output using pulse width modulation to meet the speed requirements of air-assisted seeding and achieve synchronized operation of multiple seeding rows. Simultaneously, a display screen 9 is connected to the control unit 3, providing data input, allowing the operator to set operating parameters such as the start of the operation, theoretical plant spacing, and speed settings. It also displays the current speed measurement results and seeding rate in real time, ensuring accurate and efficient seeding operations.

[0080] like Figure 3 As shown, the embodiment of the present invention provides a method and system for accurately measuring the speed of a planter using a ground speed radar based on real-time correction of the speed measurement angle, comprising the following steps:

[0081] Step 1: obtain real-time speed raw data from the ground speed radar and obtain real-time planter tilt angle from the inertial measurement unit;

[0082] Step 2: Based on the speed and angle data, the corresponding correction coefficient is calculated using the correction formula, and correction and filtering are performed to obtain the precise speed of the planter;

[0083] Step 3: Send the speed and sowing status to the display screen in real time for visual display, and receive data from the display screen to adjust the sowing status.

[0084] During system operation, the ground speed radar continuously collects real-time raw speed data from the planter as it moves, while the inertial measurement unit (IMU) collects real-time tilt angle data along all axes. These sensors are mounted on a specially designed mounting bracket. The ground speed radar ensures a constant, unobstructed view of the ground, while the IMU accurately reflects the planter's posture. This collected raw data forms the basis for subsequent calibration and processing.

[0085] After receiving speed data from the ground speed radar and tilt angle data from the inertial measurement unit, the control unit calculates a correction factor based on a pre-set correction formula and applies this correction factor to the original speed data, thereby correcting errors caused by factors such as the installation angle in real time. The corrected data then undergoes a recursive averaging filter, which takes the arithmetic average of the latest speed data and several previously collected historical data to eliminate random noise in the measurement and obtain the most accurate planter travel speed.

[0086] Accurate speed data, obtained through correction and filtering, is transmitted in real time to the display screen, which visualizes the current seeder speed and seeding status. The screen not only displays real-time data but also allows for data input, allowing the operator to enter operational parameters such as start instructions, theoretical plant spacing, and speed settings. This allows for manual intervention and dynamic adjustment of seeding conditions, ensuring that the system operates in accordance with predetermined operational requirements.

[0087] Based on accurate, calibrated and filtered speed data, the control unit outputs real-time speed control commands, adjusting the speed of the seed meter motor via PWM modulation signals to synchronize the seed discharge rate with the planter's travel speed. The entire system forms a closed-loop control circuit, leveraging sensor data feedback and interactive adjustments on the display to ensure continuous self-correction during seeding operations, achieving precise and efficient seeding.

[0088] like Figure 4 As shown, the dynamic working process is as follows:

[0089] The single-chip microcomputer cyclically sends speed measurement instructions to the radar. The radar receives the instructions and sends out a data message containing the speed measurement data. The single-chip microcomputer receives the data message and parses it to obtain the original speed measurement data, and performs recursive averaging filtering on the original speed measurement data to obtain smooth speed measurement data. At the same time, the single-chip microcomputer obtains the inclination angle of the seed drill from the inertial measurement element. Then the single-chip microcomputer calculates the corresponding correction coefficient based on the speed and angle data using the correction formula, divides the speed by the correction coefficient to obtain the corrected precise speed, and then calculates the target speed of the seed drill motor and the motor PWM according to the precise speed and sowing spacing setting. Enable the single-chip microcomputer timer interrupt. When the timer interrupt is triggered, the appropriate PWM is output to the seed drill motor to adjust the motor speed, and the speed and sowing status are sent to the display screen for visual display. The single-chip microcomputer enables the serial port interrupt and connects to the display screen. When the interrupt is captured and the sowing status debugging signal is received from the display screen, the speed measurement system is adjusted accordingly.

[0090] This invention is primarily applicable to speed-controlled seed drills, providing accurate speed information in complex environments. The seed drill then dynamically adjusts its operating state based on this speed information, ensuring operational accuracy and improving seeding uniformity, fertilization accuracy, and other agricultural operation quality. The invention can also be applied to other agricultural machinery, such as rice transplanters, fertilizer spreaders, and pesticide sprayers, which require precise motion speed information.

[0091] In this embodiment, a ground speed radar and an inertial measurement unit are used as the speed measurement modules, performing radar speed and angle measurement, respectively. A single-chip microcomputer is used as the control unit to complete system control and data processing. A serial port screen is used as the display screen, supporting touch control for human-computer interaction, displaying speed changes in a curve, and sending adjustment commands for the speed-dependent seeding system. Installation is carried out according to the installation method in the embodiment, and corresponding connections are completed using data cables.

[0092] The present invention combines an inertial measurement element with radar speed measurement, and uses the inertial measurement element to measure the radar angle to the ground in real time, thereby realizing real-time correction of the radar speed measurement results according to the radar angle to the ground, and overcoming the speed measurement error caused by changes in the radar angle to the ground due to environmental changes and machine jitters during the movement of the seed drill in complex environments. At the same time, the use of a recursive average filtering algorithm further reduces the volatility and noise in the radar speed measurement results, improves the stability and reliability of the data, and can change the filter window size to adapt to different operating environments. The correction formula used in the present invention has been verified by experiments, has strong versatility and reliability, and can provide reliable theoretical support. The speed of the seed drill after correction and filtering is reliable, with an average relative error of less than 2% and a maximum relative error of less than 10%. The actual effect of radar speed measurement in field tests is as follows: Figure 6 .

[0093] The precise speed measurement method of the present invention comprises the following steps:

[0094] The inertial measurement unit is used to measure the angle fluctuation of the actual planter during field operation and determine the range of variation. Combined with the installation angle of the ground speed radar, a trolley speed measurement platform is used to simulate the speed and angle variation range of radar speed measurement during field operation. Radar speed measurement is performed on a flat road at different speeds and ground speed radar installation angles. Several sets of data are measured to form a database of the actual usage of this radar. The database is as follows: Figure 5 .

[0095] Figure 6This is a diagram showing the radar effect provided by an embodiment of the present invention. Data calculation is performed on the database to obtain the correction coefficient of the radar under different travel speeds and ground angles. The speed measurement results and the radar ground angle are used as independent variables, and the correction coefficient is used as the dependent variable. An appropriate fitting method is used to obtain a correction formula. In this embodiment, a quadratic polynomial fitting is used, and the fitting result R-squared is 0.9956, indicating good fitting effect. The results are as follows:

[0096] k=-0.3394+0.05545x+0.004359y-0.0004413x 2 -0.00103xy+0.002182y 2

[0097] Where: x is the angle in degrees; y is the speed in meters per second; k is the correction factor

[0098] Write the correction formula into the control system and connect the components correctly;

[0099] Power on the speed measurement system, perform system initialization and system parameter settings;

[0100] Determine the appropriate recursive average filter N value according to the terrain conditions;

[0101] After power-on, the ground speed radar and inertial measurement unit automatically maintain high-frequency data measurement;

[0102] The single-chip microcomputer sends speed measurement instructions to the radar in a loop. The radar receives the instructions and sends out a data message containing speed measurement data. The single-chip microcomputer receives the data message and parses it to obtain the original speed measurement data.

[0103] The microcontroller cyclically reads the quaternion calculated by the digital motion processor built into the inertial measurement element from the inertial measurement element register;

[0104] The single chip microcomputer parses the radar data message to obtain the original speed and solves the quaternion to obtain the tilt angle of the seed drill.

[0105] The speed measurement frequency is set by the single-chip timer. After the timer interrupt is triggered, the correction coefficient k is calculated according to the original speed and the tilt angle of the planter using the correction formula. The original speed is divided by the correction coefficient to obtain the exact speed of the planter.

[0106] The precise speed of the planter is subjected to recursive averaging filtering to obtain a smooth planter speed.

[0107] The recursive average filtering process is as follows:

[0108] The recursive average filter function is called;

[0109] Move each bit of the recursive average filter data storage array forward by one bit, and the data at the top of the array will be overwritten;

[0110] Save the latest radar speed measurement results to the end of the array;

[0111] Calculate the average value of the N-bit data in the array at this time, that is, the filtering result;

[0112] Output filtering results.

[0113] Calculate the target speed of the seeding machine motor and the motor PWM according to the seeding machine travel speed, seeding spacing setting, seeding spacing and seeding machine speed;

[0114] Output appropriate PWM to the seed meter motor to adjust the motor speed, and write information such as the planter's speed and sowing status to the display register at the same time, and the display screen will visualize the data;

[0115] At the same time, the MCU monitors the sowing status debugging signal from the display screen and adjusts the speed measurement system accordingly when an interrupt is triggered. The user can enter the required operation parameters such as start operation, theoretical plant spacing, speed setting, etc. through the display screen, and observe the sowing status through the display screen.

[0116] After correction and filtering, the travel speed of the seeder is reliable, with an average relative error of less than 2% and a maximum relative error of less than 10%.

[0117] Example 1

[0118] In this embodiment, both the ground speed radar 2 and the inertial measurement unit 1 are fixedly mounted on a dedicated mounting bracket 8, which is fixed to the vertical, downward-facing side of the planter, ensuring that the ground speed radar 2 always faces the ground and is unobstructed. The upper end of the mounting bracket 8 is kept horizontal, so that the mounting surface of the ground speed radar 2 forms a fixed angle with the horizontal plane. Furthermore, the mounting bracket 8 has three mounting holes reserved for the ground speed radar 2, which are secured through holes using bolts 7 and nuts 6. For the inertial measurement unit 1, the mounting bracket 8 has a dedicated mounting slot and mounting hole, which is securely fastened within the slot using screws 9.

[0119] In this embodiment, the control unit 3 is a single-chip microcomputer. It simultaneously collects real-time raw speed data from the ground speed radar 2 and planter tilt angle data collected by the inertial measurement unit 1 through an interface. The control unit calculates a correction coefficient based on a preset correction formula, applies angle compensation to the raw speed data, and employs recursive averaging filtering—averaging the current data with several previous historical data to obtain the most accurate planter travel speed. This filtered speed data is transmitted in real time to the display screen 9 for visual display. It also drives the PWM speed control of the seed metering motor 4, achieving dynamic matching of seed discharge rate and planter speed.

[0120] Example 2

[0121] In another embodiment, the ground speed radar 2 and inertial measurement unit 1 are still mounted on a specially designed mounting bracket 8, but this bracket incorporates a shock-absorbing structure to accommodate vibration interference in harsh operating environments. Mounting bracket 8 is similarly fixed to the vertical, downward-facing side of the planter, ensuring that the ground speed radar 2 faces the unobstructed ground. Its upper end remains horizontal, ensuring that the radar forms a predetermined fixed angle with the horizontal plane. The ground speed radar 2 is still secured using bolts 7 and nuts 6 through three reserved mounting holes, while the inertial measurement unit 1 is installed in a shock-absorbing slot and secured with screws 9, thereby improving the stability of the device and data acquisition accuracy on uneven roads.

[0122] In this embodiment, the system's control unit 3 similarly collects real-time data from the ground speed radar 2 and inertial measurement unit 1, calculates a correction coefficient based on a preset correction formula, and performs angle compensation on the raw speed data. After recursive averaging filtering, the resulting precise speed data is used to adjust the speed of the seed meter motor 4. Dynamic speed regulation using PWM signals is achieved to meet the seeding speed requirements of multi-row seeding operations. Furthermore, the display screen 9 not only displays speed and seeding rate in real time but also supports manual input of operation parameters, allowing the operator to adjust the seeding conditions promptly, ensuring high precision and efficiency throughout the seeding process even in complex environments.

[0123] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with this technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered by the scope of protection of the present invention.

Claims

1. A planter ground speed radar accurate speed measurement system, characterized in that: The system includes at least: a seed row device driven by a motor; a speed monitoring module, the speed monitoring module comprising a ground speed radar and an inertial measurement element; A display screen; A control unit, whose circuit is connected to the ground speed radar, the inertial measurement element, the display screen and the seed metering device motor. The control unit receives the speed measurement data output by the ground speed radar and the seed drill inclination angle data output by the inertial measurement element, and corrects the speed measurement data according to the inclination angle data. The control unit outputs the corrected speed measurement data, and its output circuit is respectively connected to the seed metering device motor and the display screen.

2. The system according to claim 1, characterized in that The correction of the speed measurement data includes recursive averaging filtering of the speed measurement data output by the ground speed radar. The recursive averaging filtering method is: adding the current latest speed measurement data to the N-1 historical speed measurement data collected continuously before, and then dividing the sum by the total number of data points N, and the result is used as the latest filtered speed measurement data.

3. The system according to claim 1, characterized in that The control unit is provided with a data storage module, which uses an array with a length of N to store the speed measurement data output by the ground speed radar, and stores historical data in a sequential shifting manner to implement the recursive average filtering.

4. The system according to claim 1, characterized in that The inertial measurement element includes a three-axis gyroscope and a three-axis accelerometer.

5. The system according to claim 1, wherein: The inertial measurement element is provided with a 16-bit analog-to-digital conversion unit, a digital low-pass filter and a digital motion processor, and the digital motion processor outputs quaternion data after filtering.

6. The system according to claim 1, wherein: The system further comprises a PWM modulation module, which is connected to the seed metering device motor circuit, and the control unit outputs a PWM signal to adjust the rotation speed of the motor.

7. A method for accurately measuring the speed of a planter using ground speed radar, characterized in that: The method comprises the following steps: a) Collect real-time speed data from the ground speed radar and real-time planter tilt angle data from the inertial measurement unit; b) calculating a correction coefficient according to the speed measurement data and the inclination angle data, and correcting the speed measurement data; c) performing recursive averaging filtering on the corrected speed measurement data, wherein the recursive averaging filtering method comprises: calculating an arithmetic average of the latest speed measurement data and a number of previously continuously collected historical speed measurement data, and the arithmetic average is used as the filtered speed measurement data; d) outputting the filtered speed measurement data.

8. The method according to claim 7, characterized in that The recursive averaging filtering in step c comprises the following steps: The newly collected speed measurement data is stored in an array of fixed length N formed by the data storage module; Shift the original data in the array forward in sequence, and store the latest speed measurement data at the end of the array; The sum of all N data points in the array is divided by N to obtain the arithmetic mean as the filtered speed measurement data.

9. The method according to claim 7, characterized in that Acquiring the seeder inclination angle data in step a includes: Using a three-axis gyroscope to collect angular velocity data of each axis and using a three-axis accelerometer to collect acceleration data of each axis; The signals of the above sensors are collected through a 16-bit analog-to-digital conversion unit, processed through a digital low-pass filter and a digital motion processor, and filtered quaternion data is output; The quaternion data is converted into Euler angles to obtain the roll angle, pitch angle and yaw angle.

10. The method according to claim 7, characterized in that Further including: adjusting the duty cycle of the pulse width modulation signal according to the filtered speed measurement data; The pulse width modulation signal is output to adjust the rotation speed of the seed metering device motor.

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