| The food demand is increasing significant as the growing of world's population.Facing these severe food security situation,it is imperative to accelerate the research of intelligent agricultural machinery and equipment and achieve precision and sustainable agriculture.Rice is one of the most important food crops in China,accounting for about 30 % of China's total cereal planting,40 % of total grain production and 60 % of total farmers.The hard strata of paddy fields are different in depth,rugged and uneven,often with pits and gullies,and the working environment is complex,which brings challenges to the realization of intelligent and precision operation of paddy agricultural machinery.One of the main difficulties is how to achieve real-time and accurate estimate the attitude of agricultural machinery in such complex paddy field operations.Attitude measurement of agricultural machinery refers to the measurement of roll angle and pitch angle.It is the key parameters of realization of the autonomous navigational terrain tilt correction of agricultural machinery,the automatic leveling control of wide-scale agricultural implements,the construction of kinematics and dynamics model of agricultural machinery and the development of safe driving warning of field work vehicles.Under the support of the '13th Five-Year National Key R&D Program and the Guangdong Science and Technology Plan Project,this research aims to solve the problem of real-time accurate measurement of the attitude of the intelligent agricultural machinery and equipment development in the southern paddy field,and study the attitude detection of paddy field based on MEMS inertial sensor.The key technologies,the main research contents and the corresponding achievements are as follows:(1)Research on the design and development of attitude estimation hardware system for paddy field machine applications.The attitude estimation hardware system is designed and developed based on the core device include ADIS 16445 micro inertial sensor and STM32 F446 RC microprocessor.Power circuit and core device working circuit and hardware system shell were designed and development with waterproof and shock resistance.The hardware testing experiment was taken place in the laboratory.Test results show that the attitude measurement hardware system works reliably,can output sensor information stably and accurately at 100 Hz.(2)Research on sensor information processing algorithms.The existence of random disturbances leads to the generation of abnormal values,and the high-frequency output of the sensor signal is mixed with tiny burrs,which affects the system attitude estimation.A processing algorithm based on Hampel filtering and weighted moving average filtering is proposed to solve the problem of outlier identification and information smoothing.The effectiveness of the algorithm was verified by the Innova 2100 shaker.The error measurement model of gyroscope and accelerometer is studied,and the calibration and verification experiments are carried out by SGT 320 E three-axis multi-function turntable.The test results of the three-axis multi-function turntable show that the built-in three-axis gyroscope and three-axis accelerometer of ADIS16445 meet the specifications and meet the hardware requirements of the attitude detection system design.The attitude analysis methods such as Euler,four elements and direction cosine method,the attitude fusion algorithm include complementary filtering and Kalman filtering and the initial attitude estimation based on three-axis accelerometer are introduced.(3)Research on the influence of gyroscope drift characteristics on attitude estimation.With the help of ISEKI PZ604 type rice transplanter to simulate the field idle stop compensation,the influence of gyroscope drift characteristics on attitude measurement was qualitatively studied.Tests have shown that if the rice transplanter idles for 5 minutes,the gyroscope drift without correction and compensation will cause an accumulated error of the attitude angle of more than 6 degree.The idling stop identification and attitude synchronization estimation algorithm for field work vehicles were proposed,and the field test was carried out by a well-inserted rice transplanter equipped with Auto Trac autonomous navigation system.The field experiment results show that the idling stop identification and attitude synchronization estimation algorithm of field work vehicles can accurately identify the idle stop state of the working vehicle.Compared with the attitude output of the Auto Trac autonomous navigation system with GNSS compensation correction,the attitude detection of the algorithm is more accurate,smooth,and effective.(4)Research on the influence of external acceleration on attitude estimation.Design a parallel slide platform and perform a qualitative test of the influence of external acceleration on attitude estimation.Test results show that the external acceleration in the horizontal direction will have a significant impact on the attitude estimation.The external acceleration identification and attitude synchronization estimation algorithm of the field work vehicle are proposed,and the test is verified on the three-axis multi-function turntable and the paddy field laser grader loaded with MTi-300 AHRS.Test results of the turntable show that the external algorithm can accurately identify the external acceleration change when the horizontal external acceleration does not exceed 1 g.The maximum error is 0.2554 g and the average error does not exceed 0.1439 g.Field experiments show that compared with the MTi-300 AHRS,which dynamic accuracy is 0.3 degree,the average error of the roll angle measurement is 0.21 degree and the average error of the pitch angle measurement is 0.23 degree when the grader is working in a straight line.The roll angle measurement is measured when the grader turns.The average error is 0.38 degree and the average pitch error is 0.41 degree.(5)Research on attitude fusion algorithm based on adaptive Kalman filter.The transient and swaying of the wide-gauge high-altitude agricultural equipment position in paddy field operations will seriously affect the attitude measurement and work effect.An attitude fusion algorithm based on adaptive Kalman filter is proposed,and the field test is verified by the BD 982 positioning attitude measurement module and ZP 9500 high-gap sprayer platform.The experimental results show that the proposed algorithm can meet the requirements of attitude measurement of wide-width high-gap agricultural equipment under complex field conditions.Compared with BD 982,which dynamic accuracy is 0.1 degree,the average error of attitude measurement of high-gap sprayer is 0.55 degree and the maximum error is 0.91 degree.Through the test and verification of the three-axis multi-function turntable and the actual paddy field agricultural machinery platform,the results of this research provided technical guidance and theoretical basis for the R&D of real-time accurate measurement of the attitude of the intelligent agricultural machinery and equipment development in the paddy field. |
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