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Title: Use of inertial properties to orient tomatoes

item MOTABAR, P - University Of Maryland
item Lefcourt, Alan
item TASCH, URI - University Of Maryland
item Kim, Moon
item ROSTAMIAN, ROUBEN - University Of Maryland

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/14/2011
Publication Date: 2/15/2011
Citation: Motabar, Lefcourt, A.M., Tasch, U., Kim, M.S., Rostamian, R. 2011. Use of inertial properties to orient tomatoes. Transactions of the ASABE.

Interpretive Summary: The use of imaging technologies has the potential to rapidly detect defects and contamination on produce during processing. However, several problems must be resolved, including the orientation of the produce during analysis. The ability to orient produce is important for machine vision applications because it is important to know the exact location of the stem region while acquiring images. The potential use of tracks for the general transport of "round" produce compared to the conventional use of motor-driven conveyance systems has some real advantages, including much lower initial costs and essentially no maintenance costs. The critical aspects of track design include increased "bounciness," and the use of an appropriate track width relative to the tomato size. Experimental trials were conducted to determine the commercial viability of using tracks consisting of two parallel rails to orient quasi-round objects and also to determine if such tracks could be used commercially to transport "round" produce during processing. The orientation results agreed with theoretical prediction in that it was easy to orient elongated Plum tomatoes and squat Hothouse tomatoes, but difficult to orient the round Globe tomatoes. After three passes, the proper orientation of Plum and Hothouse tomatoes along most of the track was 100 percent, while the three-pass orientation for Globe tomatoes was only 90 percent and only for a short segment of the track. Optimal orientation will require developing individual tracks for each tomato cultivar. This research is of interest to food processing engineers and the produce processing industry.

Technical Abstract: Recent theoretical and experimental results have demonstrated that it is possible to orient quasi-round objects such as apples by taking advantage of inertial-effects during rotation. In practice, an apple rolled down a track consisting of two parallel rails tends to move to an orientation where the stem/calyx axis is parallel to the plane of the track and perpendicular to the direction of travel as angular velocity increases. In this study, to examine the importance of the compliance of the track on the orientation process, various track designs were tested using three tomato cultivars, Plum, Globe, and Hothouse. These cultivars represent the extremes in potential shapes that might be expected to hinder successful orientation. Preliminary tests indicated that tracks had to be optimized for each cultivar. The critical aspects of track design included increased compliance or bounciness, and appropriate width for tomato size. Plum and Hothouse single- and three-pass orientation rates at a given point along the track were around 90 and 100 percent, respectively. It was more difficult to orient Globe tomatoes as these tended to be "perfectly" round with uniform internal density; however, three-pass orientation rates approached 90 percent. Theoretically, it is impossible to use inertial properties to orient perfectly round objects with uniform density. Fortunately, round apples have lower density along the stem/calyx axis. Results of this study indicate that with proper design, the use of tracks to orient quasi-round produce or for general transport during processing is commercially viable.