[目的]开发基于星基增强精密单点定位的农机自动导航系统.[方法]以国产雷沃TX1204拖拉机为平台,采用国产星基增强定位板卡的输出数据作为农机位置反馈量,设计位速卡尔曼滤波器对定位数据进行滤波处理,开发预瞄跟随PID路径跟踪控制算法进行导航控制,整定不同行驶速度条件下的模型控制参数,采用地基增强RTK高精度定位接收机输出数据作为参考量,搭建农机自动导航测试系统并开展系统性能测试.[结果]在直线跟踪误差方面,所开发的农机自动导航系统平均误差为?0.0009436?m,标准差为0.02452?m,最大误差绝对值为0.08472?m;在邻接行误差方面,平均误差为0.0007128?m,标准差为0.02986?m,最大误差绝对值为0.15444?m.这一精度可满足大部分农机自动导航作业需求.[结论]将国产星基增强精密单点定位技术用于农机自动导航是可行的;本文设计的预瞄跟随PID路径跟踪控制模型和提出的不同速度条件下PID参数与前视距离的整定方法,提高了系统对不同速度的自适应能力.

[目的]设计一种农机前轮转角测量方法,代替安装复杂的连杆式轮角传感器.[方法]采用GNSS天线测量航向和速度,MEMS陀螺仪测量车身和车轮的合转动速率,计算MEMS陀螺仪与GNSS航向微分差值,获得车轮转动速率;设计自适应卡尔曼滤波器进行信息融合和校正,获得车轮转向角,并进行性能验证和田间应用试验.[结果]与连杆式轮角传感器测量结果对比,轮角测量方法的拖拉机在偏离航线2.5和1.5 m进行上线时,平均绝对误差(MAE)分别为1.13°和0.87°,均方根误差(RMSE)分别为0.90° 和0.68°,上线时间分别为29.4和23.5 s;以4 km/h田间导航应用时,MAE为0.44°,RMSE为0.87°,满足拖拉机旱地作业要求.[结论]GNSS航向微分和MEMS陀螺仪轮角测量方法与连杆式轮角传感器测量性能相当,能够替代轮角传感器用于较低速农业机械导航.

<span id="ChDivSummary" name="ChDivSummary" class="abstract-text">针对传统连杆式轮角传感器安装困难,提出双MEMS陀螺仪轮角测量方法测量农机转向轮角。设计Kalman滤波器消除陀螺仪零偏、随机漂移和角度积分累积误差,实时反馈校正轮角测量值,实现农机转向轮角的精准测量。验证试验结果表明Kalman滤波器的校正效果良好,双MEMS陀螺仪测量转向轮角方法可行。对比试验结果表明,该方法转向轮角测量精度与传统轮角传感器测量精度相当,2.5 m和1.5 m上线距离均方根误差分别为0.26°和0.21°;动态响应性能略逊于传统角度传感器性能,分别采用本文方法和轮角传感器进行导航,拖拉机偏离目标航线2.5 m时上线时间分别为17.9 s和15 s,偏离目标航线1.5 m时上线时间分别为16.2 s和14.2 s。两组试验结果表明,本文提出的双MEMS陀螺仪转向轮角测量方法具有较好的测量精度,适用于农机转向轮角测量,满足导航作业的需求,能够替代传统的连杆式绝对轮角传感器。</span>

复杂田间作业环境与精细作业效果要求农机装备具备实时精准感知农机具姿态的能力,田间作业时普遍存在的车辆外部加速度对此带来挑战.为进一步提高农机装备作业质量,该文以6轴微惯性传感器为硬件传感器,以方向余弦矩阵法进行姿态解算,基于一阶外部加速度模型设计卡尔曼滤波融合算法,实现动态情况下田间作业车辆外部加速度辨识与姿态精准估计.分别采用Innova 2100型摇床与装配有MTi300航向姿态参考模块的高地隙喷雾机对系统进行试验验证.摇床试验结果表明:在外部加速度小于10g情况下,系统对外部加速度辨识误差小于0.214 m/s2;田间作业高地隙喷雾机试验结果表明,相比于MTi300,横滚角最大误差为0.23°,俯仰角最大误差为0.39°.说明该文研制姿态测量系统可准确辨识外部加速度与测量姿态,研究结果可为满足精细农业作业要求的姿态测量系统研发提供依据.

以雷沃M904-D型轮式拖拉机为研究平台,采用WYH-3型无触点角度传感器,研究了轮式拖拉机转向轮角的标定和检测方法.介绍了拖拉机转向轮角度传感器的安装方法;采用带标度的转盘标定了角度传感器与拖拉机转向轮角之间的关系,标定结果表明,两者线性关系显著,相关系数超过0.99.对轮角测试中存在的误差进行分析,提出基于最小二乘原理的转向轮角零位偏差估计方法,以估计车轮相对零位偏差.路径跟踪试验结果表明,其横向跟踪偏差的绝对值极值为2.74 cm,偏差绝对值的平均值为0.49 cm,标准差为0.58 cm.提出的轮式拖拉机转向轮角测量模型在路径跟踪控制应用中表现出较好的效果,验证了转向轮角测试方案的可行性与准确性.

电动方向盘传动紧凑,对农业机械转向系统改动小,是农机自动导航技术的关键部件.该文介绍了基于电动方向盘的农机自动导航系统和电动方向盘结构特点,针对国内三款电动方向盘进行了扭矩-转速特性和正常工作电压性能测试,试验结果表明,三款电动方向盘电机的可控运行转速范围分别为0-200 r/min、0-109 r/min和0-100 r/min,输出功率大小为WA>WB>WC;电流大小为IA>IB>IC,其中A款电动方向盘带载能力最强.将A款和B款电动方向盘安装到拖拉机上进行了田间试验,结果表明A款和B款电动方向盘导航拖拉机跟踪直线路径的位置误差标准差分别为1.86 cm和1.60 cm,最大误差分别为-2.9 cm和2.9 cm.

农机导航系统的上线性能和复杂路面抗干扰能力影响着农田作业的质量和效率,为提高农机导航系统的上线速度、上线稳定性和对复杂路面的适应性,提出了一种预瞄追踪模型的农机导航路径跟踪控制方法.该方法实质是对农机运动学模型方法的改进,针对农机运动学模型小角度线性化算法中近似条件的缺点,采用预瞄追踪辅助直线引导农机快速稳定跟踪规划路径.该文参考农机运动学模型极点最优配置算法证明过程,分3步证明了该控制方法的可行性,并通过仿真和试验验证了该方法的有效性.仿真结果显示在不同的初始位置偏差和航向偏差条件下该方法都可以迅速消除偏差以稳定跟踪规划路径,位置偏差校正曲线平滑且超调量微小,说明预瞄追踪模型方法对提高农机导航系统的上线性能和抗干扰能力是有效的.田间试验结果:在初始航向偏差为0,初始位置偏差分别为0.5、1、1.5 m条件下,上线时间分别为6.8、8.2、9.4 s,上线距离分别为6.73、8.11、9.33 m,超调量分别为5.2、7.0、8.5 cm;颠簸不平旱地路面直线路径跟踪的最大误差不超过4.23 cm,误差绝对值的平均值为1 cm,标准差为1.25 cm.数据表明采用该文提出的控制方法具有良好的上线和直线路径跟踪效果,满足农业机械的导航作业要求.

[目的]更好地满足车辆自动驾驶时航向角测量的精度要求.[方法]提出卡尔曼滤波算法,把实时动态-全球导航卫星系统(RTK-GNSS)测量出来的经纬度和高程经过高斯投影转换为高斯平面坐标,和微电子机械系统(MEMS)陀螺仪测得的累积航向角进行融合处理,最终得到车辆更为精准的航向角.[结果]融合后的航向角度曲线既保持了GNSS航向的整体变化趋势,也保持了陀螺仪航向的细部变化趋势,且较GNSS和陀螺仪所得曲线更为平滑,可以跟踪车辆180°调头的转弯动作.[结论]卡尔曼滤波算法可以实时在线且精准地测得车辆航向角数据,精度较GNSS测量结果提高80％ 以上.

Automatic navigation operation has become an inevitable trend as the development of agricultural machinery and equipment. To realize the sprayer working in field with the minimal manual intervention and avoid the pesticide injury to human in manual operation, on the basis of electrification transformation of the spray machine, Lovol high clearance boom sprayer ZP9500, the automatic navigation operation system was developed based on RTK-GNSS (real-time kinematic - global navigation satellite system). Electro-hydraulic steering system with a proportional flow control valve was equipped on ZP9500, and an angle sensor was coaxially connected to steering knuckle arms, realizing the closed-loop control system for steering. For the same advantage to throttle system, a push-rod electric machine with travel sensor was installed, and the push-rod was connected to accelerator via wire rope. Installed in parallel, 2 electromagnetic relays were connected to the electronic switch of vehicle clutch and spray pump respectively, and 3 electric two-way valves were connected to 3 spray bar switches. So, the steering, accelerator, vehicle travelling, spraying and sprinkling width of sprayer could be operated in electric control. GNSS receiver with double satellite antennas and inertial sensor component, were applied in the system as the crucial position and orientation measurement equipment. Based on the hardware platform, the path planning strategy, automatic navigation controller and automatic operation controller were developed. The automatic navigation controller could guide the vehicle along the planned path generated by path planning strategy, and complete straight line tracking and headland turning. The curve tracking controller was designed based on pure pursuit model, and the linear path tracking controller was designed based on states feedback of lateral error, yaw angle and speed. And the operation controller could realize the vehicle start or stop, spraying, amplitude adjustment and speed switch control automatically according to different working conditions,such as RTK signal out of order, vehicle headland turning, and spraying operation completed. To verify the reliability and accuracy of the automatic operation system, at the speed of 1.3 m/s, the test was carried out in the field of cement pavement, dry farmland and paddy field. Due to the difference of field size and setting width, 4 rows were planned in cement pavement, 5 rows were planned in dry farmland, and 4 rows were planned in paddy field. Test result showed that: 1) The navigation operation system could automatically guide the spraying machine to complete the spraying operation in field, the switch between straight line tracking and curve tracking was smooth, and all the functions performed reliably. 2) The tracking accuracy and stability, and lateral position deviation were consistent in the same farmland, but in different conditions, it showed obvious differences. On cement pavement, when swinging on rough road, the vehicle rolling angle was from-1.6° to 1.5°, the maximum tracking error of the lateral direction was 3.9 cm, the average error of each row was from-1.0 to 0.4 cm, and the standard deviation of deviation of each row was 0.8-1.4 cm. In dry farmland, the vehicle rolling angle was from-1.4° to 3.3°, the maximum tracking error was 9.8 cm, the average error of each row was from 0.9 to 1.9 cm, and the standard deviation of deviation of each row was between 2.1 and 4.6 cm. In paddy field, the vehicle rolling angle was from-2.4° to 5.2°, the maximum tracking error was 17.5 cm, the average error of each row was between 1.4 and 2.9 cm, and the standard deviation of deviation of each row was between 3.0 and 5.2 cm. 3) By studying the tracking error and the rolling angle of each row, the maximum tracking error had significant negative correlation with the maximum rolling angle, and their negative correlation coefficient was 0.914. Meanwhile, the standard deviation of tracking error and the maximum rolling angle had the same characteristic relationship, and their negative correlation coefficient was 0.947.

Agricultural implements tilt angle measurement is one of the key technologies to achieve agricultural implements and equipment precision operations. For example, the precision navigation control and the leveling control of agricultural implements are all dependent on the accurate measurement of tilt angle. What's more, agricultural implements of tilt angle are one of the key parameters of agricultural mechanics modeling and agricultural implements safety warning learning. In order to further improve the quality of agricultural implements operation, we developed a new agricultural implement tilt angle measurement system in this paper and verified by tests on triaxial turntable platform and field. Modern micro-electromechanical systems (MEMS) technologies provide the moderate-cost and miniaturized solutions for the development of attitude reference system. Using highly-integrated inertial measurement units (IMUs) ADIS16445 provided by ADI company and micro ARM processor STM32F446 provided by ST company, we built the hardware platform. ADIS16445 ISensor? includes tri-axial gyroscopes and tri-axial accelerometers, the raw sensors data was sampled by STM32F446RC processor through SPI interface. The attitude calculation was carried out based on the Euler angle algorithm. The Kalman filter model with four state vectors and two observations was established to fuse the accelerometer and gyroscope information to achieve the accurate measurement of the tilt angle of agricultural implements. Considering the zero bias and drift characteristics of the gyroscope and the motion characteristics of the MEMS micro sensor, adaptive error covariance matrix Q and R rules were established to achieve precise tilt angle measurement of agricultural implements under different working conditions. Tests were conducted on SGT320E triaxial turntable platform and ZP9500 high level sprayer provided by LOVOL company dual in the field with the assistance of antenna positioning and attitude module BD982 provided by Trimble company. The SGT320E triaxial turntable platform was the standard equipment for testing the angular motion parameters and inertial systems. By setting the triaxial motion parameters to simulate a variety of motion states, it had speed, position and sine swing modes on all triaxial with a rate resolution of 0.0001°/s. In this paper, we used six position accelerometer calibration method and gyroscope error model to verify the performance of accelerometers and gyroscopes. Three-axis multi-function turntable test results showed that ADIS16445 built-in gyroscopes' and accelerometers' zero bias were under 0.15°/s and 0.075 mg, qualified to meet the system design hardware requirements. Kalman fusion algorithm were more accuracy and effective compare to simple integral by gyroscope and can solve the problem of zero bias and drift characteristics of the gyroscope with tilt static measurement error accuracy was 0.15°, typical dynamic measurement accuracy was 0.3°, maximum measurement error was less than 0.5°. The BD982 supports high precision positioning, attitude and heading output with high stability and fast dynamic response, which is widely used in construction implements, automobiles, agricultural implements and other fields, making it to be the leader of the industry. In this paper, the baseline length was 1.4 m with the measurement accuracy of 0.1°. Test results from high level sprayer showed that the average error of the attitude inclination was less than 0.55°, maximum measurement error was less than 0.91°, which satisfied the precise operation requirement of the agricultural equipment. Test results also verified that self-adaptive Kalman filter algorithm was more accuracy and stable than normal Kalman filter algorithm, which made the system development by this paper have more applicability. The agricultural implements tilt angle measurement system developed in this paper not only can reducing costs but also can improving the quality of agricultural implements operations.

针对密植果园或成熟果园中由于果树树冠逐渐长大使果树行距变小甚至封行,增加果树喷药难度和劳动强度、危及喷雾作业人员安全等问题,设计了一种果园管道自动顺序喷雾控制系统.该系统由喷雾给药单元、自动顺序喷雾主控器和电磁阀控制节点组成.喷雾给药单元为系统提供药液,自动顺序喷雾主控制器给电磁阀控制节点提供控制信号,电磁阀控制节点控制电磁阀的开关,通过控制果园中多个电磁阀的顺序开启和关闭,实现对果树的自动顺序喷雾.运行试验结果表明,该系统可以按照设定喷雾时间对果树进行自动顺序喷雾,不需要人工进入果园喷雾.

Aiming at overcoming the vulnerability of wired mechanical limit switch and improving the convenience of the field traction cargo vehicle working in the mountain orchard, a wireless remote control and wireless limit switch device of mountain orchard traction cargo vehicle was designed. The system was mainly composed of hall sensor module, key and code module, AVR single-chip microcontrollers, CC1020 wireless transmitting and receiving unit, PLC control unit. The system verification test of orchard showed that within 370 meters from the receiver, the wireless controlling system was 100% reliable, and the limit switch system was 100% reliable, within 45 to 95 meters to the receiver, the average path-loss of radio frequency signal of CC1020 was 32.8 dBm,which was 20.8 dBm less than the path-loss of PT2262.

In order to improve the control effect of vehicle semi-active suspension,adaptive neural network control method was developed,the air pressure of spring was taken as controlled object,the computer simulation and experiment of body plumb acceleration,suspension dynamic deflection and wheel dynamic load with semi-active air suspension under the excitations of different road surfaces were studied,the control result of neural network control suspension was compared with the control effect of passive suspension.Under the excitations of white noise roads and lower frequency sinusoid roads,the result shows that the semi-active suspension with the method not only markedly reduces body plumb acceleration,wheel dynamic load,suspension dynamic deflection,the decreased range is from 16% to 85%,but also improves automotive driving stability,riding comfortable performance and running security.3 tabs,5 figs,15 refs.