CAJ | 학술논문

在精准农业生产过程中，传感器实时采集作物信息或环境状态，传感器与作物的相对位置，直接影响到采集数据的准确性，及后期处理的效率，甚至影响到作业的效果。而田间道路、垄间颠簸，会影响传感器与作物相对位置，造成信息失真和不准确，为了减少地面不平整干扰对传感器位置的影响，该文提出了基于MEMS传感器步进电机驱动的两轴姿态调整系统。该研究分析了系统的工作原理和控制方法，以陀螺仪、重力加速度计为姿态测量元件，步进电机为驱动部件，设计基于单片机控制的两轴姿态调整系统平台软硬件结构。系统采用单片机对陀螺仪和加速度计信息的实时采样，建立了多传感信息的融合算法和姿态判定模型，可以实时分析检测对象姿态，并输出控制步进电机，对平台姿态进行补偿调整，保持控制对象的相对惯性空间方位不变，实现了平台姿态平衡的快速控制。同时系统加入了绝对位置传感器，实现初始工作状态的自动复位。测试试验结果表明，系统运行稳定，单轴姿态调整精度在平整坡路状态下最大误差在0.5°以内，在田间颠簸路况运行下最大误差在3.0°以内，能够满足信息采集和检测过程中姿态自动调整、保持相对位置的控制要求。利用该控制系统，能够提高信息采集的准确性，在精准农业生产中具有应用作用。
재정준농업생산과정중，전감기실시채집작물신식혹배경상태，전감기여작물적상대위치，직접영향도채집수거적준학성，급후기처리적효솔，심지영향도작업적효과。이전간도로、롱간전파，회영향전감기여작물상대위치，조성신식실진화불준학，위료감소지면불평정간우대전감기위치적영향，해문제출료기우MEMS전감기보진전궤구동적량축자태조정계통。해연구분석료계통적공작원리화공제방법，이타라의、중력가속도계위자태측량원건，보진전궤위구동부건，설계기우단편궤공제적량축자태조정계통평태연경건결구。계통채용단편궤대타라의화가속도계신식적실시채양，건립료다전감신식적융합산법화자태판정모형，가이실시분석검측대상자태，병수출공제보진전궤，대평태자태진행보상조정，보지공제대상적상대관성공간방위불변，실현료평태자태평형적쾌속공제。동시계통가입료절대위치전감기，실현초시공작상태적자동복위。측시시험결과표명，계통운행은정，단축자태조정정도재평정파로상태하최대오차재0.5°이내，재전간전파로황운행하최대오차재3.0°이내，능구만족신식채집화검측과정중자태자동조정、보지상대위치적공제요구。이용해공제계통，능구제고신식채집적준학성，재정준농업생산중구유응용작용。
In precision agricultural equipment automation testing process, sensors on agricultural vehicles for collecting information need to keep the relative position with the ground from impact of narrow, uneven and complicated conditions. In the requirements of obtaining accurate attitude and position about the sensors relative to the ground level and to alleviate this problem, a two-axis attitude control system based on MEMS sensors was proposed. Firstly, the operational principle and control methods were analyzed. The Euler angles coordinate transformation method was introduced which is used to describe objects position accurately in inertial space. Secondly, the hardware and software of the attitude control system were designed. The system hardware includes power supply, accelerometer and gyroscope sensors, stepping motor drive, LCD and serial communication. The control system had two axis of rotation called pitch axis and roll axis, which was driven by stepping motor in each axis. And the system was controlled by microcontroller to drive two stepping motors to keep the relative level with the ground. What is more, the accelerometer is used to measure the acceleration of gravity in the condition of static, and the gyroscope is used to measure the angular velocity, so that the attitude control system used these two MEMS sensors to estimate the platform angle. The data of the gyroscope and accelerometer are real-time sampling to gain and analyze the current attitude angle. Therefore, multi-sensor information fusion algorithm and attitude estimation model were established. The complementary filter with two kinds of sensors was used to estimate the angle which had a time constant to define where the boundary between believing in the gyroscope and believing in the accelerometer is. Specifically, for the time periods shorter than time constant, the gyroscope integration takes precedence and the noisy accelerations are filtered out. And for the time periods longer than time constant, the accelerometer average is given more weighting than the gyroscope. Thus the control system chose the appropriate parameters to estimate the accurate angle which meet the requirement of system maximum control error. Finally, The PWM signal was output by microcontroller driving to the stepping motor. Then PWM signal was sent to stepping motor actuator to make the stepping motor turn a step angle. Additionally, the PD controller was used in the system in order to achieve rapid control in order that the two-axis direction was driven by stepping motors which made a quickly response to eliminate the horizontal deviation and kept the relative position with the ground. Two absolute encoders are also fixed on each axis. They were used to keep the system automatically reset to the initial position when the system started to work. The test results show that the system runs stably and the method of estimating angle is suitable for low and middle speed changing conditions. Single axis attitude control accuracy is less than 0.5 ° in the condition of flat slope of the road and is less than 3.0 ° running in the bumpy field road. The stabilized platform system meets the demands of the attitude automatically adjust to the constant orientation in the information collection process and attitude estimation process.