Mechanical equipment is still lacking to clean the roofs of domestic Venlo-type greenhouses. The Manual cleaning can be time-consuming and labor-intensive so far. The existing solutions are relied excessively on imported equipment, resulting in high costs and maintenance expenses that significantly increased production costs. In this study, an electric roof cleaning machine was designed to automatically clean and switch the roofs of the Venlo-type greenhouses. A walking drive device was designed to ensure the consistent driving of the cleaning machine wheels, while reducing the wheel slippage on the damp tracks. A single motor was combined with a reducer and universal joint for the power transmission, in order to ensure the synchronous rotation of all four wheels. The resistance faced by the cleaning machine during movement was analyzed and calculated to determine the torque and power requirements for driving the motor. A uniform winding device was designed for uneven cable or water pipe winding during operation. The important parameters of the winding wheel were determined to accommodate the sufficient cable or water pipe length for each cleaning task. The winding and unwinding process of the uniform winding device was analyzed to clarify the impact of changes in the winding radius on the winding speed. The initial stage control of unwinding and the end stage of winding were optimized to prevent the excessive stretching of the cable or water pipe, thus avoiding a reduction in their lifespan. Reliable brushing was realized on the greenhouse roof using the cleaning roller brush. There was a contact process between the bristles and the roof surface. The roller brush fully met the design requirements to wash the roof surface under the conditions of 15 mm bristle deformation and a cleaning machine travel speed of 0.25 m/s. The torque resistance experienced by the roller brush was calculated to obtain the motor power required for the driving rotation of the roller brush. Some installation of switching tracks and positioning markers was carried out for Venlo-type connected greenhouses, in order to ensure the smooth progress of the switching operation. The rational design was achieved in the automatic water supply system for the auxiliary switching platform and the switching control system. A safety redundant control system was designed using multiple sensor perceptions for the cleaning machine. The various motor operations were controlled in an orderly manner, in order to collect the processing signals, such as the edge, departure detection, coiling, and skylight opening signals. A prototype was fabricated to conduct the test greenhouse, followed by performance testing of the prototype. The test results indicated that the cleaning machine achieved the maximum operating speed of 0.265 m/s, with a stop margin of 28.4 mm. The average switching time was 22.84 s, and the average alignment error between the platform and the roof track was 1.6 mm. An experiment was conducted to evaluate the cleaning effectiveness of the machine using the transmittance rate of the film as an indicator. The results showed that the transmittance rate increased to 86% after cleaning under the conditions of a travel speed of 0.25 m/s, roller brush speed of 120 r/min, and water pump flow rate of 34 L/min using a film with an initial transmittance rate of 68%. Better cleaning performance was achieved during operation. The cleaning machine can fully meet the cleaning requirements of Venlo-type greenhouse roofs. It is of significant importance in the indoor temperature and light environment, as well as the higher fruit yield and quality.

Uprightness can be one of the most important indicators in the process of garlic mechanized sowing. However, the conventional duckbill sowing device has been one of the key bottlenecks in garlic mechanized sowing, due to its structural defects. Among them, the collapse of seeds can be triggered by the failure of the inner wall support during the opening of the traditional duckbill. It is still lacking in the high uprightness of the garlic seeds during sowing, resulting in low planting quality and yield. This study aims to improve the stability of the garlic‐seed uprightness using structural modifications. A quantitative analysis was made to explore the influence of the pre‐added soil on the attitude stability of the garlic seeds; A dynamic interaction model was constructed for the soil–device–seed under the new opening structure; A series of tests were carried out to verify and optimize the different structural parameters for the high sowing quality; According to the discrete element method (EDEM 2021), an interaction model was constructed to contain the soil, the duckbill device, and Cangshan garlic cloves. Hertz–Mindlin (no slip) contact model and inter‐particle parallel bonding were employed to simulate the cohesion and properties of the spherical soil particles. The distribution of the particle size was set as 0.5-2.0 mm. A two-stage experimental design was adopted after optimization. In the first stage, the attitude was systematically analyzed in the percentage height of the garlic seeds buried in the pre-added soil (five gradients: 0, 25%, 50%, 75%, and 100%). In the second stage, two types of perforated structures—Transverse and Longitudinal—were selected to regulate the soil inflow by the varying hole width (6.5 mm), hole length (30 and 25 mm for the Transverse structure, 40 mm for the Longitudinal structure). Finally, a bench test was carried out to quantitatively analyze the test data via image processing using a high-speed camera. The results showed that the pre-added soil shared a significant regulatory effect on the seed stability. In the virtual simulation, when the pre-burial rates were 0, 25%, 50%, 75%, and 100%, the average decreases in the seed uprightness were 33°, 22°, 10°, 4°, and 3°, respectively. The rate of decrease was diminished, as the pre-burial rate increased. In the bench-top validation, the corresponding decreases were 38°, 26°, 13°, 6°, and 4°, respectively. Notably, the decrease in the uprightness tended to stabilize under both conditions at the pre-burial rates ≥ 75%. After structural optimization, the Transverse perforated design (top hole 30 mm and bottom hole 25 mm) was achieved at an 87.5% pre-burial rate at a 6.5 mm hole width. While the longitudinal perforated design (hole length 40 mm) was achieved at 77.5%. Bench-top measurements were obtained with the actual pre-burial rates of 80% (transverse) and 72% (longitudinal), respectively. Compared with the traditional non-perforated structure, the Transverse perforated device improved the seed uprightness by 59.27%, and the longitudinal by 44.05%, fully meeting the theoretical predictions. The localized perforated duckbill structure effectively alleviated the support failure during the opening stage of the traditional device, when introducing a controllable soil‐compensation mechanism. Theoretical analysis and experimental validation demonstrated that the two-segment transverse perforated structure improved the seed-clove uprightness by 59.27%. These findings can provide a promising technical path for the profiling mechanisms in the precision garlic sowing equipment. The important engineering value can also be provided to advance the mechanical planting of economic crops

Chinese greenhouses have been widely used with planting areas exceeding 810,000 hm² in northern China, due to heat preservation, low investment, and energy saving. The plastic film of greenhouses cannot be washed by less rain in the northern region for an extended period. The accumulation of more dust can also reduce the light conditions in the shed, leading to adverse effects on the growth and development of crops. Consequently, it is very necessary for regular shed cleaning. In this study, a fully automatic cleaning machine of greenhouse film was proposed for the labor-saving and high efficiency. The machine included a cleaning host, floor and roof lateral shifting devices, as well as a control system. The cleaning host consisted of a bracket, brush, support wheel, climbing motor, brush motor, and water spray pipe. The roof lateral shifting device comprised a hanging rail, stainless steel pulley assembly, hanger, roof lateral shifting motor, polyurethane wheel, and control system. The ground lateral shifting device was composed of a flip frame, bearing bracket, rear axle assembly, water tank, and control system. A 433 MHz wireless module was selected to communicate between the floor and roof lateral shifting device conveyor over a distance of up to 200 m. A double worm gear motor was used to drive the brush and climbing shaft of the cleaning host, in order to reduce the weight of the entire machine for cost saving. A ground lateral shifting device was designed to carry the cleaning host along the length of the greenhouse. The roof lateral shifting device was designed for automatic line wrapping cleaning. The installation height of the roof lifting rope was determined to avoid interference during the lateral shifting operation, even damage to the film. Multi-sensor fusion and data verification were utilized for the real-time, consistency, and reliability of cooperation between the cleaning host, roof and ground lateral shifting device. A model greenhouse was then made to verify the rationality and feasibility of the design. The prototype parameters of span, ridge height, and shoulder height were used at the scaling ratio of 10:1. The prototype was then processed and cleaned, according to the external dimensions at 5:1. Alignment, tilt deviation, and cleaning tests were conducted to verify the performance. The results showed that the horizontal offset during the lifting and lowering of the cleaning host was within ±3°, the left and right offset was within ±7 mm, and there was no offset during the lateral shifting. There was approximately 1 mm in the single and cumulative lateral shifting errors of the floor and roof lateral shifting devices. The average light intensities were 107 232.38, 77 866.77, and 112 377.26 lx with/without the cleaning shed and the cleaning reference, respectively. The relative transmittance of the film increased from 69.3% to 95.4% after cleaning, indicating the well-designed brush material and key parameters of the machine. A remarkable cleaning performance was achieved on the surface of the film. The cleaning machine with the large weight in the early stage can also be updated for the high automation level, less film damage and cleaning blind zone. The findings can provide a strong reference for the design and development of film-cleaning equipment in the greenhouse.