Research On Modeling And Control Of Agricultural Wheeled Robot

Along with the rapid development of economy and the improvement of science and technology,agricultural techniques are being steadily improved.Agricultural production mode has great changes and intelligentization has become a trend in the future development of agricultural machinery.Because of the rapid development of information technology,our country start to develop precision agriculture in the 1990 s.Application and extension of agricultural robot is one of the important standards for the development level of precision agriculture.Agricultural robot is a full automation or semi-automation machine which has various new technologies,it can imitate human to complete agricultural production task.Agricultural robot can improve the efficiency of agricultural production and reduce the intensity of the farming work,it is the coming direction of intelligent development of agricultural machinery in our country.Along with the development of agricultural robot,mechanical structure of agricultural robot has become much more complicated and degree of freedom of mechanism has being increasing.Robot modeling precision will be affected by mechanical machining error and external interference in the actual working process.Traditional mathematics modeling method can not meet precise control demand.It is more and more important to establish a precise model and design an efficient control algorithm.This paper is supported by national natural science fundation of china: Research on dynamic modeling and control of underactuated agricultural wheeled robot(51205238).The main contents are listed as follows:(1)On the basis of understanding domestic and foreign agricultural robot technology,the design scheme and technical route of agricultural wheeled robot was determined.The whole mechanical system was divided into two parts: wheeled mobile platform and 6-DOF manipulator part.Wheeled mobile platform is made up of five parts,front-wheel steering mechanism,rear-wheel drive mechanism,bodywork fixed installation plate,automatic control room and battery box.Joints of 6-DOF manipulator are all the rotating joints and the manipulator meet the Pieper criteria.Through changing end-effecter it can meet the needs of modern agricultural production,such as picking,spraying and collecting information.(2)The coordinate description of objects in 2D space and 3D space is studied based on screw theory.The kinematics model of the robot is developed and then forward and inverse kinematics of 6-DOF manipulator has been analyzed in this paper.Inverse kinematics algorithm for manipulator based on BP neural network is designed to reduce the influence of external interference to the inverse kinematics calculation.Simulation results in MATLAB and Mathematica validates the correctness of kinematic calculation program and the rationality of the structural design of manipulator.(3)The dynamic modeling of the manipulator is carried out using Lagrange method.PI-SMC dynamic control algorithm is designed combined with RBF neural network theory,PID control theory and sliding mode control theory.Route planning algorithms based on SMC theory are designed using two wheeled mobile robot model and the rationality of it is proved in simulink simulation.(4)Robot supporting hardware and software of control system are designed.Information communication between host computer and slave computer is done through wireless bluetooth module.The control program based on C language of STM32 MCU is accomplished to control the whole robot.Prototype machine agricultural wheeled robot is developed and insufficients are found by fruit and vegetable picking experiment.Improvement and optimization are proposed for the shortcoming.