Using vibration mechanical tools for plum harvesting

The mechanical basis of fruit detachment by vibration, have been studied since the 60’s when the first branch and trunk shakers were constructed. In investigation on wood mechanical properties by theresonance vibration method, described wood as polymeric materials and put them in the category of visco elastic materials. So wood mechanical properties are defined in terms of elastic solids and viscous liquids. A trunk shaker was operated with adequate duration to remove more than 90% of mature fruit or with excessive shaking time under various environmental conditions and drought stress treatments throughout the harvest season. However, tree configuration and fruit injury are major constraints to the adoption of mechanical harvesting. In prior work with a canopy shaker, promising results were attained after critical machine components were reconfigured. Theoretical analysis of the dynamic response of plum tree branches to low energy excitations can be helpful in the design and use of devices to sense fruit removal during thinning operations. This investigation has been conducted to improve mechanical thinning by exciting individual branches at a precise frequency and duration to achieve a superior distribution of fruit remaining on the tree. Harvesting machines generally detach fruits from the plum plant by vibration and/or impact. This vibration is consequently transmitted to the branches, causing the fruit to detach. The major benefit of mechanical harvesting relies on its efficiency and lower costs in comparison to harvesting by hand, thereby increasing grower profit. Between traditional hand picking methods on the one hand and modern powered machinery on the other, there is a type of mechanical device for plum harvesting that can be considered "intermediate". Currently, moving machines are now available for high production levels, such as vibrating shakers that can be fitted to tractors, or telescopic lifting devices and moving harvesters that derive from plum harvesters. From a technical point of view they can be described in various ways: plum shaker combs, beaters or shakers; these are managed by the operator and allow a considerably higher harvesting yield when compared with the hand picking method. This shaker shows great potential for use in harvesting plum but further study is required in order to design a more automated prototype. The proposed electromechanical limb shaker reduced plum fruit movement as compared to conventional trunk shakers, while still achieving adequate fruit detachment. Fruit injury occurs by fruit impacting limbs and other fruit. The proposed limb shaker reduces plum fruit motion before and after detaching and may reduce fruit injury compared with a conventional shaker. This limb shaker was developed with the final goal of interfacing it to an autonomous system. The ability to identify the limb for shaking and the amount of plum fruit needed to be removed from the tree is possible with some modifications of this system. Shaker pad placement could be facilitated by marking a portion of the plum tree with paint. This limb marking would greatly aid a machine vision system’s accuracy that would automate the system.

کلیدواژه ها:

Shaker ، Vibration ، Visco elastic material ، Harvest ، Plum