Abstract: Pressure atomization immunization can be confined to the high noise, uneven size distribution of droplets, and low effective inhalation rate in poultry houses. This study aims to design the piezoelectric component with the microporous ultrasonic atomization in an immunization robot. The performance of spray immunization robots was also improved in the caged poultry houses. A multi-physics coupled model of the atomizing plate was established using finite element simulation software. In the boundary conditions, the fixed constraints were applied to the edges of the atomizing plate in order to simulate the assembly clamping. While a driving voltage was applied on the upper surface of the piezoelectric ceramic, where the interface contacting the metal substrate was set as the ground potential. In the mesh generation, a physics-controlled adaptive strategy was adopted with local refinement to the key areas, such as the interface between the piezoelectric ceramic and the metal substrate. The vibration modes and frequency response were analyzed to determine the optimal resonant frequency of 113 kHz. An equivalent circuit model was used to accurately represent the piezoelectric oscillation behavior of the atomizing plate. The formula derivation showed that the equivalent impedance of the series matching network was primarily resistive when the circuit operated near the resonant frequency. At this point, there was no phase difference between the driving voltage and the input current. As such, the resonant working state was effectively determined to check whether the phase relationship between voltage and current was zero. A precision spray control was proposed using PI frequency tracking, in order to prevent some changes in the resonant characteristics of the atomizing plate due to the prolonged operation and environmental factors. The voltage and current signals were collected at both ends of the atomizing plate. The power factor angle was then calculated to compare the current phase difference with the reference value under resonant conditions. This phase error served as the input to the PI controller. A control signal was then generated after adjustment. Its output frequency was adjusted for the dynamic compensation in the attenuation of the atomizing plate's vibration. A modular component of immunization atomization was integrally designed in an spray immunization robot of a poultry house. Specifically, the spray immunization robot consisted of a mobile platform, an atomization and control system. Some sensors were also used in the crawler chassis for the autonomous movement and navigation within the poultry house. Its atomization system included a medicine tank and multiple nozzles with atomizing plates, thus forming a sealed circulation channel of medicinal fluid. A remote terminal was employed to set the parameters of the robot. Unmanned immunization spraying was then automatically carried out using the given plan. Static single-nozzle atomization tests were finally conducted to verify the immunization robot application. The results showed that the test group of PI frequency tracking achieved a 1.57% increase in the average atomization amount after the atomizing plate for 1 h, compared with the fixed resonant frequency. Some measurements were also taken with A HELOS/VARIO laser particle size analyzer at a distance of 30-50 cm from the nozzle. It was found that the proportion of droplets meeting the required size for immunization spray reached 90.81%. In the actual poultry house, the water-sensitive paper was used to capture the aggregated droplets caused by multiple airflows during the robot's movement. There was an average droplet size increase of 42.81 μm, compared with the static laboratory environment. The overall proportion of droplets with the required size for immunization spray reached 90.2%, fully meeting the droplet size requirements for poultry house spray immunization. The findings can provide the technical support for the spray immunization robots in poultry houses.