Aiming at the difficulty of mechanized picking of camellia fruit in complex working environments such as hilly and mountainous areas with low mechanization suitability and strip-plantation Camellia oleifera forest, we designed a light and simple mobile vibration picking device for camellia fruit.

Taking Changlin series Camellia fruit as the research object, the technical scheme of light and simple mobile camellia fruit vibration picking device was designed, including the mechanical structure of the vibration picking head, the excitation mechanism, the electric clamping head and the power walking mechanism. The forced vibration dynamic model of Camellia oleifera fruit was established. Taking the picking net rate of camellia fruits as the index, and the height of the clamping position from the ground, vibration frequency and vibration time as factors, a three-factor three-level orthogonal test response surface analysis was designed, and the picking effect test of the device was carried out at Shanxia forest farm in Fenyi County, Jiangxi Province.

The passing ability test of the device shows that the device passes smoothly in hilly and mountainous areas with complex terrain conditions such as steep slopes and narrow slopes and strip-type camellia forest land, and the minimum through width is 75 cm. The maximum harvesting rate obtained by the picking test was 89.73%, and the corresponding picking parameters were: the clamping position was 45 mm from the ground height, the vibration frequency was 26 Hz, and the vibration time was 4 s. The results of orthogonal test showed that the order of influence of three factors on the harvesting rate of camellia fruit was: clamping position from the ground height > vibration frequency > vibration time. The results of response surface analysis showed that when the vibration frequency was constant, with the increase of the height from the clamping position to the ground, the harvesting rate of camellia fruit increased first and then decreased. When the clamping position is at a certain height from the ground, with the increase of vibration frequency, the harvesting rate decreases first and then increases. When the clamping position is at a certain height from the ground, there is no obvious relationship between the camellia fruit harvesting rate and the vibration time. When the vibration time is constant, the harvesting rate increases first and then decreases slowly with the increase of the height from the clamping position to the ground. The optimal combination of picking parameters is as follows: the distance between the clamping position and the ground is 54 cm, the vibration frequency is 26 Hz, and the vibration time is 4 s. The average harvesting rate of the optimized parameters is 86.98%, and the error with the optimized value is within 5%, indicating that the optimization model is reliable.

The device designed in this study has good passing ability in complex terrain with low mechanization suitability, such as hilly and mountainous areas and strip-plantation Camellia oleifera forest. It is capable of efficiently performing the harvesting operation of camellia fruit.

At present, most of the collection parts in the mechanized harvesting of Camellia oleifera fruits adopt inverted umbrella-type collection devices, with various forms such as human-machine combination, automation, and intelligence, but the collection mechanism has not been studied. This paper conducted experiments on the determination of the collision restitution coefficient between Camellia oleifera fruits and umbrella cloth in the collection mechanism, to provide a theoretical basis for the optimal design of the inverted umbrella-type collection device for Camellia oleifera fruits.

Using the designed and developed measuring device for the coefficient of restitution of umbrella-surface collision to simulate the fruit dropping and collecting parts during the mechanized harvesting process of Camellia oleifera fruits. Combine two high-speed cameras to record and analyze the test process. Through single - factor preliminary selection tests and multi - factor orthogonal tests, explore the effects of fruit dropping height, umbrella cloth material, tension force on the umbrella cloth, and the angle between the umbrella -cloth and the horizontal plane on the coefficient of restitution of the collision between Camellia oleifera fruits and the umbrella cloth. Determine the primary- and -secondary order of the influence of each factor on the coefficient of restitution of the collision between Camellia oleifera fruits and the umbrella cloth and the significance level of each factor. After conducting performance measurement tests on the prototype through optimized design, the fruit collection rate and concentration rate are obtained.

1) The analysis shows that the primary and secondary order of the influence of the four factors on the collision restitution coefficient is: the angle between umbrella cloth and horizontal plane, umbrella cloth material, tension force of umbrella cloth, fruit dropping height; 2) The selected optimal parameter combination is the angle between umbrella cloth and horizontal plane of 25°, umbrella cloth material of canvas, and tension force of umbrella cloth of 20 N. 3) Through performance measurement tests on the inverted umbrella-type collection device optimized in design, the fruit collection rate is 95.29%, and the fruit concentration rate is 93.41%.

This research reveals the main influencing factors of the restitution coefficient when Camellia oleifera fruits collide with the umbrella cloth, and presents an optimal parameter combination. It provides references for the optimal design of the inverted umbrella-type Camellia oleifera fruit collection device and a theoretical basis for improving the fruit collection rate and concentration rate of the Camellia oleifera fruit collection device.