Modeling And Identification Of Four-Wheel Independent Electrically Driven High Clearance Sprayer

With the continuous development of urbanization and the gradual intensification of the aging population,China's agricultural population continues to decrease.Under such circumstances,agricultural production and management will inevitably gradually shift to mechanization and intelligence.As a high-efficiency field plant protection tool,the high clearance sprayer has a good control effect on diseases,insects and weeds of crops at all stages.The existing high clearance sprayer is mainly a mechanical transmission,hydraulic power steering structure,when working in muddy paddy fields,it is easy to sink into the mud and cannot turn,or even damage the chassis.The fourwheel independent electric drive high clearance sprayer studied in this paper is powered by a wheel hub motor.Due to its special self-steering chassis structure,it only needs to control the four wheel differentials to complete the steering without external assistance,but the control performance of the system is proposed.Higher requirements.In this paper,the link constrained self-steering structure is designed first,then the kinematics model and the controller based on the kinematics model are designed,and finally the dynamic model is established and the parameter identification is completed.The main research contents are as follows:(1)Four-wheel independent electric drive high clearance sprayer chassis constraint connecting rod design.Based on the basic self-steering structure of the high clearance sprayer chassis,the connecting rod constraint scheme is designed.The front and rear steering bridges are linked to obtain the constrained self-steering structure.The equations are established using the geometrical relationship of the chassis structure.The minimum deformation becomes the target selected link installation position.The connecting rod restraint scheme has low cost and convenient production and processing,and has been applied to sprayers.(2)The kinematics model of the four-wheel independent electric drive high clearance sprayer was established and the motion controller was designed based on this.First build the chassis kinematics model,then design the upper layer wheel speed distribution controller and the lower layer wheel speed tracking controller based on the kinematics model,and finally conduct the test,the results show that: on a flat road,the speed tracking curve rise time is 1.9s,and the corner tracking curve rise time is 2.0s,which meets the application requirements;the steering bridge rotation angle has a maximum value of 7.5 ° near the desired rotation angle when crossing 11 cm high obstacles shock;normal walking function when working in the field,enough to cope with most field work scenes.(3)A four-wheel independent electric drive high clearance sprayer dynamics model was established.First,the corresponding coordinate system is established with the earth and the movable parts of the chassis,and then the kinetic energy and the generalized force are calculated separately,and the dynamic equation is solved using the Lagrange equation.(4)Design parameter identification experiment of chassis dynamic model and use least square method to complete parameter identification.First,the Euler integral is used to discretize and simplify the dynamic equation to the least square format;then build a test platform,install a differential GPS system to obtain the spatial coordinates and yaw angle of the sprayer,and collect the steering bridge rotation angle and motor voltage input;After the acquired data is processed by Gaussian smoothing and coordinate transformation,the least square method is run once to complete the algorithm to obtain the model parameters.