Spray deposit distribution from a field sprayer is mainly affected by the boom movements when the tractor is driven over a rough soil surface, the pendulum suspension that used to reduce and control the movement of spray boom by isolating the boom from vibrations of the tractor will directly enhance uniform deposition of chemicals. However, how to match the parameters of the suspension with the properties of the boom is the key problem. The dynamic rigid-flexible coupling model of the virtual prototype of the spray boom suspension system was established by using ADAMS and ABAQUS software. An optimization of the suspension parameters for a large spay boom was carried out based on the optimal Latin hypercube design, radial basis function neural network, and multi-objective genetic algorithm NSGA-II. After modified parameters of the suspension, the travel of the sprayer on a typical field motion track was simulated based on a six DOF motion simulator, and the dynamic behavior of the boom suspension was measured. The results show that RMS of the measured boom roll angle and the boom center displacement for optimized solution were reduced by 14.76% and 12.43% compared with the original suspension. Finally, the inertial measurement unit (IMU) was used to measure the movements of the sprayer vehicle during the pesticide application on the Hongze Lake Farm, the experiment of field condition reproduced by using the six DOF motion simulator, the standard deviation of the roll angle and vibration displacement for the optimized sprayer boom are only 0.6382° and 62.279 mm respectively. The research provides theoretical basis and experimental method for parameter optimization of large scale boom suspension.

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Boom sprayer is one of the most commonly used plant protection machinery for spraying pesticide. Studies have shown that the efficiency of chemicals is highly correlated with the uniformity of spray distribution patterns. As the boom is a large and flexible structure, boom rolling leads to overlapping and leakage of the pesticides. In order to improve spray uniformity, the boom attitude should be kept parallel to the ground slope or to the crop canopy beneath the boom. Passive suspension can attenuate frequencies above its resonance frequency, but nothing can be done to align the boom to the sloping ground. Therefore, an active suspension system is designed, which includes DSP-based controller, a servo valve, a hydraulic cylinder, two ultrasonic sensors, one inertial attitude sensor, and the developed control procedures. In order to prevent the wrong response of the control system caused by the high frequency component due to uneven crop canopy or rough ground. A special signal processing algorithm was proposed, including the limiting filter, smoothing algorithm and data fusion algorithm based on optimal weight. The transient and steady-state performances of the boom control system using velocity feedforward PID algorithm were tested on a six DOF motion simulator. It can be seen that the low-frequency tracking performance of the boom was greatly improved after the electro-hydraulic active suspension was added. At the resonance frequency, the peak angle of active suspension and passive suspensions are 0.72° and 1.29° respectively, and the resonance peak is greatly reduced. The controller was implemented on a self-propelled boom sprayer and validated under field conditions, the standard deviation of the roll angle of the boom with active suspension is 0.40°, compared with 1.04° of the sprayer chassis. Experimental results show that the active suspension control system can effectively reduce the effect of ground excitation disturbance on the application process, and has good tracking performance for low frequency terrain change.