基于GNSS姿态与电机编码器的农机转向角度测量系统研制  

Development of agricultural machinery steering wheel angle measuring system based on GNSS attitude and motor encoder

作　　者：陈云 何艳 Chen Yun;He Yan(Xi’an UniStrong Navigation Technology Co.,Ltd.,Xi’an 710065,China;School of Communications and Information Engineering,Xi’an University of Posts and Telecommunications,Xi’an 710121,China)

机构地区：[1]西安合众思壮导航技术有限公司,西安710065 [2]西安邮电大学通信与信息工程学院,西安710121

出　　处：《农业工程学报》2021年第10期10-17,共8页Transactions of the Chinese Society of Agricultural Engineering

基　　金：北斗卫星导航系统重大专项(GFZX0305030112)。

摘　　要：典型的农业机械自动驾驶系统需要在车辆转向轮上安装角度传感器测量转向角度,存在安装不便与可靠性差问题。该研究提出一种基于GNSS模块和电机编码器组合的转向轮转向角度测量系统。该系统通过组合利用GNSS姿态测量值与运动模型得到转向轮期望角度,利用电机转向速度和全液压转向阀的传递模型推算转向角度变化值,经卡尔曼滤波融合解算得到车辆转向轮的实时转向角度。与霍尔式绝对角度传感器对比的动态测试结果表明,该系统在直线行驶时的测量标准方差小于0.91°,在转向轮-10°~+10°区间,测量标准方差小于1.0°;直线自动驾驶作业时的导航误差小于2.5 cm,曲线作业自动驾驶的导航误差小于9.0 cm,满足农机自动调头等场景应用。Measuring steering wheel angle in real-time normally requires accurate installation and reliability in a typical auto-pilot sensor system for agricultural machinery.There are mainly three types of steering wheel angle measurement at present.In the first type,the displacement sensors are widely used to measure the stroke of the steering cylinder,thereby indirectly obtaining the steering angle.In the second type,the resistive or magnetic angle sensors(hall-type)are used to measure the kingpin rotation angle,and then geometric relations are used to calculate the steering angle.In the third type,a gyroscope was selected to measure the angular rate of the steering axle for the angle increment.Nevertheless,all these types need to be updated,when connecting to the navigation controller of a tractor.The first type requires easy installation and high reliability.The second type has high detection accuracy,but also needs easy installation.Since the third type is simple to install,the angle accuracy depends mainly on the gyro’s zero drift,random drift and cumulative error.In this study,a measuring system of steering wheel angle was proposed using the combination of GNSS attitude and motor encoder.In this system,there was no need to install sensors on the steering wheels,or connect to the navigation controller.Firstly,the tractor attitude and ground speed were captured with a high precise GNSS terminal(MC4),and then the reference point of the vehicle precisely compensated the ground speed under the lever arm compensation with the roll and heading of a tractor.A dynamic motion model was selected to roughly calculate the wheel steering angle of the vehicle using the measuring system of steering angle.Secondly,a transfer model was established to real-time measure the steering wheel angle rate using the encoder of the electric wheel,thereby obtaining the steering axle angle rate,particularly considering the linear features of full hydraulic steering gear and the noise of hydraulic leakage.Thirdly,a Kalman filter was used to ob

关 键 词：农业机械 自动驾驶 卫星导航 转角测量 姿态测量 电机编码器 

分 类 号：TP368[自动化与计算机技术—计算机系统结构]