Seeding machine ground speed radar precision speed measurement method and system based on real-time correction of speed measurement angle

Abstract

The application belongs to but is not limited to the technical field of speed measurement system, and discloses a seeding machine ground speed radar accurate speed measurement method and system based on speed measurement angle real-time correction, which 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 speed data from the radar and a seeding machine inclination angle from the inertial measurement element, corrects and filters the speed measurement result to obtain an accurate seeding machine running speed, and then adjusts the motor speed according to the accurate speed.The application uses recursive average filtering to filter the radar speed measurement result, effectively suppresses high-frequency noise and random error, combines the data of the gyroscope and the accelerometer through a quaternion attitude solution algorithm, corrects long-term cumulative error, realizes accurate tracking of the complex dynamic attitude of the seeding machine in the running process, uses a correction formula to calculate a correction coefficient according to the radar speed measurement result and the angle measurement result, and corrects the radar speed measurement result with the correction coefficient to obtain high-precision radar speed measurement result.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of intelligent agricultural equipment, and relates to a seeding machine ground speed radar accurate speed measurement method and system based on speed measurement angle compensation real-time correction. BACKGROUND

[0002] Seeding is an important link in agricultural production. With the development of social economy and the progress of agricultural machinery technology, seeding gradually changes from traditional manual seeding to seeding machine seeding, greatly improving the efficiency of seeding and reducing the labor intensity. Speed matching is the key to realizing high-performance seeding, which specifically adjusts the seed discharge speed of the seed metering device according to the real-time running speed of the seeding machine to ensure that the seeds are evenly distributed according to the seeding requirements.

[0003] The traditional seeding machine measures the speed through the ground wheel and transmits the torque through the mechanical transmission system to drive the seed metering device to work at the speed, realizing speed seeding. However, there are problems such as ground wheel slip speed distortion, soil adhesion blocking ground wheel speed measurement, and difficulty in stepless adjustment of seeding amount, which do not meet the requirements of intelligent high-performance seeding in production. Intelligent electric drive seeding has become a development trend. In the intelligent electric drive seeding technology, accurate real-time speed measurement of the seeding machine is the key. Currently, there are two main ways to measure the speed of the seeding machine. One is to measure the speed of the wheel, such as Hall sensor and encoder; the other is to measure the speed of the vehicle body, such as Beidou satellite positioning module speed measurement and radar speed measurement. Among them, the Hall sensor and the encoder are usually coaxially installed with the tractor wheel shaft or the ground wheel shaft, and the running speed of the seeding machine is obtained by measuring the number of revolutions of the wheel in unit time. The speed measurement is real-time, but there are problems such as slipping, blocking and stopping during operation. Satellite positioning obtains the position and speed of the tractor by analyzing the message information, but it is easily affected by the strength of the satellite signal and has a certain lag. The real-time performance of the microwave radar speed measurement result is high, but its measurement accuracy is very sensitive to the installation angle of the radar.

[0004] For example, the Chinese patent with the publication number CN115061129A "Intelligent control method for precision seeding machine based on Doppler radar speed measurement" measures the running speed of the implement through the Doppler radar. The radar in this invention is fixedly installed at an angle of 55° with the ground, and directly controls the motor speed of the seed metering device according to the speed measurement result. This invention ignores the influence of the radar on the ground angle caused by the bouncing and shaking of the seeding machine and the change of the terrain during actual field operation, which further affects the stability and accuracy of the speed measurement.

[0005] For example, Chinese patent CN116087898A, "An Inertial Navigation Compensation Method and Inertial Navigation Compensated Radar Speed ​​Measurement System," calculates the vehicle's tilt angle by real-time acceleration acquired by an inertial measurement unit, and uses this angle to calculate the compensation value of the vehicle's speed, thereby obtaining a more accurate vehicle speed after compensation. This invention is mainly applied to rail transit equipment, operating in stable, high-speed environments, and using empirical correction coefficients. In complex terrain and low-speed operation in agricultural fields, accelerometers are easily affected by linear acceleration and external factors such as vibration and temperature changes. Furthermore, in scenarios with rapid dynamic changes, their measurement accuracy can be affected.

[0006] Based on the above analysis, the urgent technical problem to be solved in the existing technology is: the technical problem that changes in the radar antenna illumination angle caused by machine vibration during operation affect the radar speed measurement results. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a method and system for accurate ground speed measurement of seeders using radar based on real-time correction of the speed measurement angle. The specific technical solution is as follows:

[0008] A method and system for accurate ground speed measurement of a seeder based on real-time correction of the speed measurement angle using radar. The speed measurement method involves using an inertial measurement element to measure the real-time tilt angle of the seeder, correcting the radar speed measurement results, and performing recursive averaging filtering to finally obtain a high-precision real-time travel speed of the seeder.

[0009] A method and system for precise speed measurement of a seeder using ground speed radar based on real-time correction of speed measurement angle. The speed measurement system includes a seed metering device driven by a motor, a speed monitoring module, and a control unit for implementing the precise speed measurement method. The speed monitoring module includes a ground speed radar and an inertial measurement unit. The control unit calculates a correction coefficient based on the speed data obtained from the radar and the seeder tilt angle obtained from the inertial measurement unit, corrects the radar speed measurement result, then performs recursive averaging filtering on the corrected speed measurement result to obtain the precise speed of the seeder, and finally adjusts the motor speed according to the precise speed of the seeder. The speed measurement system also includes a display screen.

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

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

[0012] Step 2: Based on the speed and angle data, calculate the corresponding correction coefficient using the correction formula to obtain the corrected accurate speed, and adjust the seed metering motor speed.

[0013] Step 3: Send the speed and sowing status to the display screen in real time for visualization, 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 in three axes, and the accelerometer can measure the acceleration in three axes. In addition to providing 16-bit ADC signal acquisition functions for 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 calculation. The control unit converts the quaternion into Euler angles to obtain the accurate pitch angle, that is, the angle between the seeder and the horizontal.

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

[0016] The correction factor is obtained by dividing the radar velocity measurement result by the reference velocity, 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 various scenarios is constructed. Using speed measurement results and radar-to-ground angle as independent variables and correction coefficients as dependent variables, a quadratic polynomial is used for fitting to obtain a correction formula. This formula is then input into the control unit. In practical applications, based on radar speed measurement results and angle measurement results, the control unit calculates the correction coefficients. Subsequently, these correction coefficients are used to correct the radar speed measurement results, thereby obtaining high-precision speed measurement data.

[0020] Furthermore, a recursive average filter is used to filter the radar velocity measurement results. The recursive average filter refers to taking the average of the latest measurement result and the previous N-1 measurement results as the latest measurement result. The formula is as follows:

[0021]

[0022] In the formula, y[n]: the output value after the nth filtering; x[nk]: the original data value of the past n sampling times; N: the window size of the average value, i.e. the number of historical data points involved in the calculation.

[0023] The specific process for implementing recursive averaging filtering is as follows: An array with length N is set up in the control unit as a radar speed measurement data storage device. This array is then used to implement recursive averaging filtering, as shown below:

[0024] To obtain the new radar speed measurement result, shift each data point in the array forward by one position.

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

[0026] Calculate the average value by taking the arithmetic mean of N data points in the array.

[0027] Output the filtered results.

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

[0029] Another objective of this invention is to provide a precise speed measuring device for a seeder, comprising a precise speed measuring method and system based on real-time correction of the speed measuring angle using a ground speed radar. The precise speed measuring device includes a seed metering device driven by a motor, a speed monitoring module, a display screen, and a control unit for implementing the precise speed measuring method. The speed monitoring module includes a ground speed radar and an inertial measurement unit (IMU). The ground speed radar measures the real-time travel speed of the seeder, and the IMU obtains the seeder's tilt angle. The control unit is a microcontroller, and the display screen is connected to the control unit. The display screen has data input and data display functions, allowing manual input of required operating parameters, such as start of operation, theoretical plant spacing, and speed setting, while also displaying current speed measurement results and seeding rate parameters.

[0030] Furthermore, the ground speed radar and inertial measurement unit are mounted on a mounting frame, which is fixed to the vertically downward side of the seeder to ensure that the radar faces the ground without obstruction, and the upper surface of the mounting frame is horizontally mounted. At this time, the angle between the mounting surface of the radar and the horizontal plane is a specific angle. The mounting frame has a pre-drilled mounting hole for the radar, and bolts and nuts are used to pass through the radar and the mounting frame to tighten and fix it. For the inertial measurement unit, a mounting slot and a mounting hole are pre-drilled, and the inertial measurement unit is placed into the mounting slot and tightened and fixed with screws.

[0031] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this invention are as follows:

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

[0033] This invention combines data from gyroscopes and accelerometers using a quaternion attitude calculation algorithm. It utilizes the high dynamic response characteristics of gyroscopes for short-term attitude prediction and uses information from accelerometers to correct long-term cumulative errors, thus achieving accurate tracking of the complex dynamic attitude of the seeder during its movement.

[0034] This invention uses a correction formula to calculate correction coefficients based on radar speed measurement results and seeder attitude measurement results during actual radar speed measurement, and then uses the correction coefficients to correct the radar speed measurement results to obtain high-precision radar speed measurement results.

[0035] Current seeder speed measurement methods simply use radar, without considering the changes in the ground speed radar's angle to the ground caused by complex terrain, mechanical vibration, and changes in operating speed during operation. This results in deviations in 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 the attitude and speed information of the seeder are dynamically changing during the actual sowing process. How to quickly correct the radar speed measurement results while acquiring attitude data in real time; the complexity of the farmland environment requires the speed measurement system to have strong robustness and anti-interference ability; and to obtain the correction formula by fitting a large amount of experimental data for the measurement error of the radar under different ground angles and speeds, while ensuring that the formula is applicable to various terrains and operating conditions.

[0037] This invention acquires the attitude information of a seeder in real time using an inertial measurement unit (IMU). The IMU's built-in digital motion processor, combined with a gyroscope and accelerometer, can output the seeder's attitude information at high frequency, providing fundamental data for the correction of radar speed measurement results. During the research and development phase, this invention experimentally obtained radar speed measurement data at different angles and speeds, using encoder speed measurement results as actual speed reference values, and establishing a correction formula through a fitting algorithm. Recursive averaging filtering is applied to the radar speed measurement results to reduce fluctuations and errors. Furthermore, the size of the filtering window can be adjusted to adapt to various terrains and operating conditions.

[0038] The relevant code, including the correction formula, recursive filtering, inertial measurement element data reading, and human-machine interaction, is written into the control unit. During actual sowing, this invention reads radar velocity measurement results and seeder attitude information, and dynamically corrects the radar velocity measurement results by calculating correction coefficients based on the correction formula, real-time attitude information, and velocity measurement data, outputting high-precision real-time velocity information. The radar velocity measurement results, the corrected results, and the filtered results are as follows. Figure 6 This effectively reduces radar speed measurement errors and fluctuations. The seeder's travel speed, after correction and filtering, is reliable, with an average relative error of less than 2% and a maximum relative error of less than 10%.

[0039] This invention relates to a precise speed measurement method and system for seeders based on real-time correction of the speed measurement angle using ground speed radar. This system can obtain higher-precision real-time seeder travel speed and adapt to complex environments such as slopes and rugged terrain. The technical solution of this invention is simple and efficient, easily integrated into existing agricultural machinery, and can provide accurate speed information for speed-sensitive seeding machinery, effectively ensuring seeding uniformity, reducing missed or double-seeding problems caused by speed fluctuations, and significantly improving operational quality and agricultural production efficiency. Furthermore, this invention can be extended to precision-controlled rice transplanters, fertilizer applicators, sprayers, and other equipment requiring precise movement speed information.

[0040] Secondly, this invention, through a precise speed measurement method and system for seeders based on real-time correction of the speed measurement angle using ground speed radar, can accurately acquire real-time speed data of seeders during operation at low cost. The technical solution of this invention is simple and efficient, easily integrated into existing agricultural machinery, and its low-cost speed measurement scheme helps reduce the price of agricultural machinery. It has extremely high market demand and commercial potential, and can be needed by various agricultural machinery manufacturers. Applied to large-scale seeding machinery, it provides precise speed information support for seeding operations, facilitating precision seeding, avoiding over-seeding or under-seeding, improving crop growth conditions, and increasing yield. Simultaneously, this invention can be extended to variable-rate fertilization and pesticide spraying operations on ground implements, reducing fertilizer and pesticide usage and environmental impact.

[0041] This invention designs a low-cost radar precision speed measurement system with angle compensation for seeder operations. The radar speed measurement results are corrected in real time according to the radar's ground angle during the seeder's movement, effectively reducing speed measurement errors in complex terrain.

[0042] Foreign companies like the US-based Diepower Corporation produce radar-III speed sensors with a wide speed measurement range and accurate results. Through on-site calibration, the sensors can achieve a speed error of 1%-3%. Domestic manufacturers include Hubei Yongxiang, which uses radar to determine operating speed and adjust seeding rate in real time, achieving a seeding accuracy of over 98%. While both offer high speed measurement accuracy, their high prices make them difficult to accept in the market. This invention achieves low-cost, high-precision speed measurement, effectively filling the technological gap in high-precision speed measurement for agricultural seeders both domestically and internationally.

[0043] The development of precision agriculture places higher demands on the real-time control and operational accuracy of agricultural machinery. However, the industry currently lacks a low-cost solution that can provide high-precision real-time speed measurement for agricultural machinery. Traditional agricultural machinery speed measurement often uses single-sensor solutions such as ground speed radar, encoders, and BeiDou speed measurement, which suffer from weak anti-interference capabilities and inability to adapt to complex environments. The technical solution of this invention fills this technological gap, realizing low-cost radar-based accurate speed measurement of seeders during operation, and providing technical support for the upgrading of precision agriculture equipment. Attached Figure Description

[0044] Figure 1 This is a structural diagram of the precise speed measurement method and system for a seeder based on real-time speed angle correction provided in this embodiment of the invention.

[0045] Figure 2 This is an installation structure diagram of the precise speed measurement method and system for a seeder based on real-time speed angle correction provided in this embodiment of the invention;

[0046] Figure 3 This is a flowchart of the precise speed measurement method and system for a seeder based on real-time speed angle correction provided in this embodiment of the invention.

[0047] Figure 4 This is a dynamic workflow diagram of the precise speed measurement method and system for a seeder based on real-time speed angle correction provided in this embodiment of the invention.

[0048] Figure 5 These are the radar measurement speed results and fitting results at different angles and speeds provided in the embodiments of the present invention;

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

[0050] In the diagram: 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 Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0052] like Figure 1 As shown, this invention provides a method and system for precise speed measurement of a seeder using ground speed radar based on real-time correction of the speed measurement angle. The speed measurement system includes a seed metering device driven by a motor, a speed monitoring module, 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 control unit calculates a correction coefficient based on the speed data obtained by the radar and the seeder tilt 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 precise speed of the seeder, and finally adjusts the motor speed according to the precise speed of the seeder. The speed measurement system also includes a display screen.

[0053] The core components of an inertial measurement unit (IMU) are a gyroscope and an accelerometer. The gyroscope measures angular velocity along three axes, and the accelerometer measures acceleration along three axes. In addition to acquiring signals from the three-axis gyroscope and accelerometer sensors, the IMU integrates a digital low-pass filter and a digital motion processor, directly outputting quaternion data after low-pass filtering and quaternion attitude calculation. Converting this quaternion to Euler angles yields accurate roll, pitch, and yaw angles, as shown in the following formulas:

[0054]

[0055] θ = arcsin(-2(q1q3-q0q2))

[0056]

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

[0058] This invention utilizes a quaternion-based solution from the digital motion processor built into an inertial measurement unit (IMU) to calculate the change in the seeder's angle relative to the ground during its movement. This IMU employs quaternion attitude calculation, an algorithm that combines data from a gyroscope and an accelerometer to calculate the seeder'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 susceptibility of single sensors to noise interference. Specifically, a gyroscope provides high-precision angular velocity information and can obtain the attitude angle through integration, but the error accumulates over time. An accelerometer, on the other hand, measures the components of gravitational acceleration in three axes and calculates the attitude angle through arctangent, but it is not suitable for complex and variable working environments. The quaternion attitude calculation algorithm cleverly combines the data from both, utilizing the high dynamic response characteristics of the gyroscope for short-term attitude prediction while using accelerometer information to correct for long-term accumulated errors, thus achieving accurate tracking of the complex dynamic attitude of the seeder during its movement.

[0059] To address the significant impact of ground-angle variations on radar speed measurement results, a vehicle-mounted speed measurement platform was used to simulate the speed and angle variations encountered during radar operation in the field. Radar speed measurements were conducted on a flat road surface at different speeds and ground-angle settings to obtain speed measurement results under varying conditions. The correction coefficient was 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 various scenarios is constructed. Using speed measurement results and radar-to-ground angle as independent variables and correction coefficients as dependent variables, a polynomial fitting is used to obtain a correction formula. This correction formula is then written into the control unit. During actual radar speed measurement, the correction formula is used to calculate correction coefficients based on radar speed measurement results and angle measurement results, and these correction coefficients are used to correct the radar speed measurement results, resulting in high-precision radar speed measurement results.

[0063] Recursive averaging filtering is used to filter radar velocity measurement results. When a seeder is operating in the field, the vibration of the implement causes high-frequency vibrations and measurement errors in the radar velocity measurement results, making them unsuitable for direct use in a speed-based seeding system. Recursive averaging filtering uses the average of the latest measurement result and the previous N-1 measurements as the latest measurement result, as shown in the formula below:

[0064]

[0065] In the formula, y[n]: the output value after the nth filtering; x[nk]: the original data value of the past n sampling times; N: the window size of the average value, i.e. 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. Furthermore, the advanced nature of recursive averaging filtering lies in its ability to adapt to different sowing environments by adjusting the N value. For example, a larger N value increases the number of measurement data points involved in the average calculation, resulting in a smoother filtered signal, reduced signal fluctuations and noise, and improved accuracy. However, it decreases the signal's sensitivity to environmental changes and its real-time performance, making it suitable for flat farmland and improving signal accuracy. Conversely, a smaller N value has the opposite effect, making it suitable for farmland with significant topographical undulations and ensuring real-time signal performance.

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

[0068] An array with length N is set up in the control unit as a radar speed measurement data storage device. The recursive average filtering is implemented using this array, as follows:

[0069] To obtain the new radar speed measurement result, shift each data point in the array forward by one position.

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

[0071] Calculate the average value by taking the arithmetic mean of N data points in the array.

[0072] Output the filtered results.

[0073] The speed control of the brushless DC motor is achieved using PWM modulation. By adjusting the PWM duty cycle, the seed metering speed can be effectively controlled, enabling precise sowing. The magnitude of the PWM signal is calculated and dynamically adjusted by the controller based on real-time acquired and corrected filtered radar speed data, as well as preset agronomic requirements. This not only adapts to complex environmental changes in field operations but also ensures the uniformity and efficiency of seed metering, improving operational quality.

[0074] System installation as follows Figure 2 As shown, the ground speed radar 2 and inertial measurement element 1 are mounted on a mounting frame 8. The mounting frame 8 is fixed to the vertically downward side of the seeder, ensuring that the ground speed radar 2 faces the ground without obstruction, and the upper surface of the mounting frame 8 is horizontally mounted. At this time, the angle between the mounting surface of the ground speed radar 2 and the horizontal plane is a fixed angle. Specifically, the mounting frame 8 has three pre-drilled mounting holes for the ground speed radar 2, and bolts 7 and nuts 6 are used to pass through the radar and the mounting frame 8 to tighten and fix it; for the inertial measurement element 1, a mounting slot and mounting holes are pre-drilled, and the inertial measurement element 1 is placed into the mounting slot and tightened and fixed with screws 9.

[0075] Connections such as Figure 1 The precision speed measurement system has one seed metering motor 4, which adopts air-driven seeding and can perform seeding operations on multiple seeding rows simultaneously. 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 and data display functions, which are used for manual input of the required operation parameters, such as start operation, theoretical plant spacing, speed measurement settings, etc. At the same time, the display screen 9 can display the current speed measurement results and seeding quantity and other parameters.

[0076] Both the ground speed radar 2 and the inertial measurement unit 1 are fixedly mounted on the mounting frame 8, which is fixed to the vertically downward side of the seeder to ensure that the ground speed radar 2 always faces the ground without obstruction. The upper surface of the mounting frame 8 is horizontally mounted, so that the mounting surface of the ground speed radar 2 forms a fixed angle with the horizontal plane. Specifically, the mounting frame 8 has three pre-drilled mounting holes for the ground speed radar 2, and bolts 7 and nuts 6 are used to fasten the ground speed radar 2 and the mounting frame 8. For the inertial measurement unit 1, the mounting frame 8 is designed with a dedicated mounting slot and mounting hole. After it is placed in the mounting slot, it is fixed with screws 9.

[0077] The system's ground speed radar 2 collects real-time ground speed data during the seeder's forward movement, while the inertial measurement unit 1 collects the seeder's tilt angles in different directions using a built-in three-axis gyroscope and three-axis accelerometer. Data from both sensors undergoes analog-to-digital conversion, followed by preliminary processing using a digital low-pass filter and a digital motion processor to convert it into digital signals, providing a foundation 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 element 1, the control unit 3 first calculates the correction coefficient based on the tilt angle data to compensate the radar speed measurement data for angle. The compensated speed measurement data is further processed using a recursive average filtering method, which calculates the arithmetic average of the latest collected speed measurement data and several previously collected historical data to obtain an accurate speed measurement result.

[0079] After filtering and correction, the speed measurement data is used by control unit 3 to adjust the speed of seed metering motor 4 in real time. Pulse width modulation is used to output the speed control signal to meet the requirements of pneumatic seeding for seed metering speed, enabling synchronous operation of multiple seeding rows. Simultaneously, display screen 9 is connected to control unit 3, providing both data input functionality, allowing the operator to set operation parameters such as start time, theoretical plant spacing, and speed measurement settings, and real-time display of current speed measurement results and seeding rate, ensuring accurate and efficient seeding operations.

[0080] like Figure 3 As shown, this invention provides a method and system for accurate ground speed measurement of a seeder using radar based on real-time correction of the speed measurement angle, including the following steps:

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

[0082] Step 2: Based on the speed and angle data, calculate the corresponding correction coefficients using the correction formula, perform correction and filtering, and obtain the precise speed of the seeder;

[0083] Step 3: Send the speed and sowing status to the display screen in real time for visualization, 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 generated by the seeder during its movement, while the inertial measurement unit (IMU) collects real-time tilt angle data along each axis of the seeder. All of these sensors are mounted on specially designed mounting brackets, with the ground speed radar ensuring it always faces the ground without obstruction, and the IMU accurately reflecting the seeder's attitude information. This collected raw data forms the basis for subsequent calibration and processing.

[0085] After receiving the speed data from the ground speed radar and the tilt angle data from the inertial measurement unit, the control unit calculates the corresponding correction coefficient according to a pre-set correction formula and applies this correction coefficient to the original speed data, thereby correcting errors caused by factors such as installation angle in real time. The corrected data then undergoes recursive averaging filtering, which involves arithmetically averaging the latest speed measurement data with several previously collected historical data points to eliminate random noise in the measurement and obtain an accurate seeder travel speed.

[0086] The accurate speed data, obtained after correction and filtering, is transmitted to the display screen in real time for visualizing the current seeder speed and sowing status. The display screen not only shows the real-time collected data but also has a data input function, allowing the operator to input operating parameters such as start command, theoretical plant spacing, and speed settings. This enables manual intervention and dynamic adjustment of the sowing situation, ensuring the system operates according to predetermined operating requirements.

[0087] Based on the accurate speed data after correction and filtering, the control unit outputs speed adjustment commands in real time, adjusting the speed of the seed metering motor through PWM modulation signals to achieve synchronous matching between the seed dispensing rate and the seeder's travel speed. The entire system forms a closed-loop control loop, utilizing sensor data feedback and interactive adjustments on the display screen to ensure continuous self-correction during the sowing operation, thereby achieving precise and efficient sowing.

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

[0089] The microcontroller continuously sends speed measurement commands to the radar. The radar receives the commands and simultaneously sends a data message containing the speed measurement data. The microcontroller receives and parses the data message to obtain the raw speed measurement data, and performs recursive averaging filtering on the raw speed measurement data to obtain smooth speed measurement data. At the same time, the microcontroller obtains the tilt angle of the seeder from the inertial measurement element. Then, based on the speed and angle data, the microcontroller calculates the corresponding correction coefficient using the correction formula. The speed is divided by the correction coefficient to obtain the corrected accurate speed. Then, based on the accurate speed and the seed spacing, the target speed of the seed metering motor and the motor PWM are calculated. The microcontroller enables a timer interrupt. When the timer interrupt is triggered, an appropriate PWM is output to the seed metering motor to adjust the motor speed. At the same time, the speed and seeding status are sent to the display screen for visual display. The microcontroller enables a serial port interrupt and connects to the display screen. When an interrupt is captured and a seeding status debugging signal is received from the display screen, the speed measurement system is adjusted accordingly.

[0090] This invention is primarily applied to speed-controlled seeders, providing precise speed information to the seeder in complex environments. The seeder then dynamically adjusts its operating status based on this speed information, ensuring operational accuracy and improving seeding uniformity, fertilization precision, and other agricultural operation quality. Simultaneously, this invention can be applied to other agricultural machinery, such as rice transplanters, fertilizer applicators, and sprayers, which require precise speed information.

[0091] In this embodiment, a ground speed radar and an inertial measurement unit are selected as the speed measurement module to perform radar speed measurement and angle measurement, respectively; a microcontroller is selected as the control unit to complete system control and data processing; a serial port screen is selected as the display screen to support touch control for human-computer interaction, displaying speed changes as curves and sending adjustment commands to the speed-following sowing system. Installation is performed according to the method described in this embodiment, with corresponding connections completed using data cables.

[0092] This invention combines inertial measurement units (IMUs) with radar speed measurement. By using IMUs to measure the radar's ground-facing angle in real time, it enables real-time correction of radar speed measurement results based on the ground-facing angle. This overcomes speed measurement errors caused by changes in the radar's ground-facing angle due to environmental variations and machine vibrations during seeder movement in complex environments. Simultaneously, a recursive averaging filtering algorithm further reduces fluctuations and noise in the radar speed measurement results, improving data stability and reliability. The filtering window size can also be adjusted to adapt to different operating environments. The correction formula used in this invention has been experimentally verified, demonstrating strong versatility and reliability, and providing reliable theoretical support. The seeder speed 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 radar speed measurement performance in field trials is as follows: Figure 6 .

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

[0094] The angular fluctuations of the actual seeder during field operation were measured using an inertial measurement unit to determine the range of variation. Combined with the installation angle of the ground speed radar, a trolley-based speed measurement platform was used to simulate the speed and angular variation ranges of the radar during field operation. Radar speed measurements were conducted on a flat road surface at different speeds and ground speed radar installation angles, collecting several sets of data to create a database of the radar's actual usage. The database details are as follows. Figure 5 .

[0095] Figure 6This is a radar effect diagram provided in an embodiment of the present invention. Data calculations are performed on the database to obtain correction coefficients for the radar under different travel speeds and ground-facing angles. Using the speed measurement results and the radar's ground-facing angle as independent variables and the correction coefficients as dependent variables, an appropriate fitting method is used to obtain the correction formula. In this embodiment, a quadratic polynomial fitting is used, and the fitting result R-square is 0.9956, indicating a 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 corrected formula into the control system and connect each component correctly;

[0099] The speed measurement system is powered on to perform system initialization and system parameter settings.

[0100] Determine the appropriate recursive average filter value N based on the terrain conditions;

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

[0102] The microcontroller sends speed measurement commands to the radar in a loop. The radar receives the commands and simultaneously sends a data message containing the speed measurement data. The microcontroller receives the data message and parses it to obtain the raw speed measurement data.

[0103] The microcontroller cyclically reads the quaternion calculation results from the inertial measurement element's built-in digital motion processor from the inertial measurement element's register;

[0104] The microcontroller parses the radar data message to obtain the raw speed and solves the quaternion to obtain the tilt angle of the seeder.

[0105] The speed measurement frequency is set using a microcontroller timer. After a timer interrupt is triggered, the corresponding correction coefficient k is calculated using a correction formula based on the original speed and the seeder's tilt angle. The original speed is then divided by the correction coefficient to obtain the precise speed of the seeder.

[0106] A recursive average filter is applied to the precise speed of the seeder to obtain a smooth seeder speed.

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

[0108] The recursive average filter function is invoked;

[0109] Shift each data element of the recursive average filter data storage array one position forward, and overwrite the data at the beginning of the array.

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

[0111] Calculate the average of the N data points in the array at this point, which is the filtering result;

[0112] Output the filtered results.

[0113] The target speed and PWM of the seed metering motor are calculated based on the seeder's travel speed, the seed spacing settings, the seed spacing, and the seed metering motor speed.

[0114] The appropriate PWM is output to the seed metering motor to adjust the motor speed, and at the same time, information such as the seeder's travel speed and sowing status is written to the display register, and the display screen displays the data visually.

[0115] Meanwhile, when the microcontroller monitors the sowing status adjustment signal from the display screen, it adjusts the speed measurement system accordingly upon interruption. Users can input the required operating parameters, such as start operation, theoretical plant spacing, and speed measurement settings, through the display screen, and simultaneously observe the sowing status.

[0116] After correction and filtering, the seeder's travel speed 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 element 1 are fixedly mounted on a dedicated mounting bracket 8. This mounting bracket is fixed to the vertically downward side of the seeder, ensuring that the ground speed radar 2 always faces the ground without obstruction. The upper surface of the mounting bracket 8 remains horizontal, so that the mounting surface of the ground speed radar 2 forms a fixed angle with the horizontal plane. At the same time, the mounting bracket 8 has three pre-drilled mounting holes for the ground speed radar 2, which are fixed by bolts 7 and nuts 6. For the inertial measurement element 1, the mounting bracket 8 is designed with a dedicated mounting groove and mounting holes, and it is firmly fixed in the mounting groove using screws 9.

[0119] In this embodiment, the control unit 3 is a microcontroller that simultaneously acquires real-time raw speed data from the ground speed radar 2 and seeder tilt angle data from the inertial measurement unit 1 via an interface. The control unit calculates a correction coefficient based on a preset correction formula, performs angle compensation on the raw speed data, and uses a recursive average filtering method—that is, arithmetically averaging the current data with several previous historical data points—to obtain the latest speed measurement data and thus a precise seeder travel speed. The filtered speed data is transmitted in real-time to the display screen 9 for visualization and simultaneously drives the PWM speed control of the seed metering motor 4, achieving dynamic matching between the seed dispensing rate and the seeder speed.

[0120] Example 2

[0121] In another embodiment, the ground speed radar 2 and the inertial measurement unit 1 are still mounted on a specially designed mounting bracket 8, but this bracket incorporates a shock-absorbing structure to withstand vibration interference in harsh operating environments. The mounting bracket 8 is also fixed to the vertically downward side of the seeder, ensuring that the ground speed radar 2 faces the unobstructed ground; its upper surface remains horizontal, ensuring that the radar forms a predetermined fixed angle with the horizontal plane. The ground speed radar 2 is still fixed using bolts 7 and nuts 6 through the three pre-drilled mounting holes, while the inertial measurement unit 1 is installed in a groove with shock absorption and secured with screws 9, thereby improving the stability of the equipment and the accuracy of data acquisition under rough terrain conditions.

[0122] In this embodiment, the system's control unit 3 also collects real-time data from the ground speed radar 2 and the inertial measurement element 1, and calculates correction coefficients according to a preset correction formula to perform angle compensation processing on the original speed measurement data. After recursive averaging filtering, the obtained accurate speed data is used to adjust the rotational speed of the seed metering motor 4, using a PWM signal to achieve dynamic speed regulation to meet the seed metering speed requirements of multi-row seeding operations. Simultaneously, the display screen 9 not only displays the speed and seeding rate in real time but also supports manual input of operating parameters, enabling the operator to adjust the seeding status in a timely manner and ensuring that the entire seeding process maintains high precision and efficiency even in complex environments.

[0123] The above description is merely 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 those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A precise speed measurement system for a seeder using ground speed radar, characterized in that, The system includes at least: A seeder, which is driven by an electric motor; A speed monitoring module, which includes a ground speed radar and an inertial measurement unit; One display screen; A control unit, whose circuit is connected to the ground speed radar, inertial measurement element, display screen and seed metering motor, receives the speed measurement data output by the ground speed radar and the seeder tilt angle data output by the inertial measurement element, corrects the speed measurement data according to the tilt angle data, and outputs the corrected speed measurement data. Its output circuit is connected to the seed metering motor and the display screen respectively. Using the speed measurement results and the radar's ground angle as independent variables and the correction coefficient as the dependent variable, a quadratic polynomial is used to fit the formula to obtain the correction formula. The correction formula is then input into the control unit, which calculates the correction coefficient based on the radar speed measurement results and the angle measurement results.

2. The system as described in 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 as follows: add the latest speed measurement data to the previously collected N-1 historical speed measurement data, and then divide the sum by the total number of data points N. The result is used as the latest filtered speed measurement data.

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

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

5. The system as described in claim 1, characterized in that, The inertial measurement unit is equipped with a 16-bit analog-to-digital converter, a digital low-pass filter, and a digital motion processor. The digital motion processor outputs quaternion data after filtering.

6. The system as described in claim 1, characterized in that, The system further includes a PWM modulation module connected to the seed meter motor circuit, and the control unit outputs a PWM signal to adjust the speed of the motor.

7. A method for accurate ground speed radar measurement of a seeder, characterized in that, The method includes the following steps: a) Collect real-time velocity data from ground speed radar and real-time tilt angle data of the seeder from inertial measurement unit; b) Calculate the correction coefficient based on the speed measurement data and tilt angle data, and correct the speed measurement data accordingly; c) Perform recursive average filtering on the corrected speed measurement data. The recursive average filtering method is as follows: calculate the arithmetic mean of the latest speed measurement data and several previously continuously collected historical speed measurement data, and use the arithmetic mean as the filtered speed measurement data. d) Output the filtered speed measurement data; Using the speed measurement results and the radar's ground angle as independent variables, and the correction coefficient as the dependent variable, a quadratic polynomial is used to fit the formula to obtain the correction formula. The correction formula is input into the control unit, which calculates the correction coefficient based on the radar speed measurement results and angle measurement results.

8. The method as described in claim 7, characterized in that, The recursive averaging filter in step c includes the following steps: The latest collected speed measurement data is stored in an array of fixed length N composed of data storage modules; The existing data in the array are shifted forward sequentially, and the latest speed measurement data is stored at the end of the array. The arithmetic mean of the sum of all N data points in the array is obtained by dividing by N, and this arithmetic mean is used as the filtered speed measurement data.

9. The method as described in claim 7, characterized in that, The step a of obtaining the seeder tilt angle data includes: The angular velocity data of each axis is collected using a triaxial gyroscope, and the acceleration data of each axis is collected using a triaxial accelerometer. The signals from the aforementioned sensors are acquired by a 16-bit analog-to-digital converter and processed by a digital low-pass filter and a digital motion processor to output filtered quaternion data. The quaternion data is converted into Euler angles to obtain the roll angle, pitch angle, and yaw angle.

10. The method as described in claim 7, characterized in that, Further includes: Adjust the duty cycle of the pulse width modulation signal based on the filtered speed measurement data; The pulse width modulation signal is output to adjust the speed of the seed metering motor.

Images