| With constant progress in the agricultural modernization,plant protection equipment has become indispensable in large-scale agricultural production and the agricultural industrialization.Furthermore,it is also fast evolving to become intellectualized and larger-sized.The technology for efficient and precise pesticide application adopted in large-sized lever-type plant protection equipment not only greatly improves the agricultural production efficiency but also significantly reduces the waste of pesticide.The tracking and control of spray lever is the key technology for ensuring precise pesticide application of large-sized lever-type equipment.In view of complicated indefinite interference such as uneven ground due to field operation environment faced by spray lever suspension system of plant protection equipment,as well as the nonlinearity and time variability of hydraulic components and valves after long time operation,it’s of great theoretical significance and practical application value to study how to accurately control position of spray lever.Therefore,the following main works were carried out:First,analysis was conducted on the working principle of spray lever system of modern large lever-type plant protection equipment during operation.According to Class II Lagrange kinetic equation,a mechanism model was established for spray lever suspension system with a double pendulum structure,followed by an engineered state space model,thus laying a foundation for controller design.Second,a sliding mode controller was designed based on Stochastic Configuration Network(SCN)with regard to the established mathematical model,as well as changes of system parameters of plant protection equipment and great external interference,etc.The ride gain of sliding mode was adjusted dynastically through SCN.Furthermore,system stability was proved with Lyapunov.When the system error is large,it is fast reduced;if it is small,the variation amplitude of controlling quantity is lowered.In this way,smooth change and strong robustness of controlling quantity are achieved.In simulation experiment,the travelling of plant protection equipment on different grounds was simulated.The result suggested that the designed controller enabled fast adjustment of the angle of plant protection equipment’s spray lever to achieve tracer control of canopy of crops under different operation conditions.With nearly zero outputtracking error,the controller demonstrated satisfactory dynamic performance.Finally,according the functional requirement on control of plant protection equipment’s variable flow,an embedded control system with STM32F407 as the main control chip was designed,followed by the design of software and hardware for embedded controller of plant protection equipment spray lever.As to the researched control algorithm,engineering transplantation was conducted in embedded development environment.With simulated circuit test box and spray lever parameters,the circuit model of simulated spray lever suspension was established and connected with the embedded controller to form a closed-loop control system.The test result suggested that the system operated stably and that the output of controlled objects was stabilized around the set value with error which satisfied the engineering requirements.Furthermore,external interference was effectively inhabited with the system. |
