Akira Sasao

Mobile Fruit Grading Robot -Concept and prototype-

In this study, a mobile fruit grading robot for information-added product in precision agriculture was developed. The prototype robot, which consisted of a manipulator, an endeffector, a machine vision system, and a mobile mechanism, was made. The robot could acquire five fruit images from four sides and the top while its manipulator transported the fruit received from the operator. A preliminary experiment was conducted with 372 samples of sweet pepper in variety of “TosahikariD ” in laboratory. A fruit mass prediction method was developed by use of the five images. Results indicated that the fruit mass was successfully estimated with projection areas for the variety.

Theoretical Possibility of Lotka-Volterra Competition Model to be Applied on Plants Ecosystem

Abstract Density dependence and symmetrical competition were dealt with by the modified Lotka-Volterra model. Distance function w as incorporated into the model and parameter studies basedon the model were conducted to model the density dependence. Feasibility of the logistic model was discussed. Experimental datafor clover-weedcompetition process were obtained and nonlinear regression was conducted based on the non-symmetrical model. The non-symmetrical model showed good agreement with experimental data.

Study of Efficient Lighting Periods Based on Plant Stoma Reaction

The objective of this study was to detect the plant stoma response under the lighting conditions of continuous and 1 to 15 minutes of lighting. In this study, a real-time measurement system was developed to observe a living plant stoma continuously for a long period in a growth chamber, using a microscope and a color TV camera. A video recording system was adopted to obtain details of stoma movement, and images were captured every 30 seconds. From the experimental results, it was observed that the stoma opened slowly 5 minutes after the lights were turned on, and then opened rapidly until it reached the maximum pore size. In guard cells, light stimulus activates a proton pump, the resulting hyper polarization of the plasma membrane opens voltage-sensitive K+ channels, and then the water entering the guard cells opens the stoma after the K+ ions have entered. This process may cause 5 minutes of delay, and delay was also observed after the light was turned off. 10 minutes of lighting opened the stoma to the maximum size. For better utilization of lighting, it was suggested to turn a light on 10 minutes at 30 minuets before the lighting period to open stomata widely at the beginning of the lighting period, so then plants can start the photosynthesis immediately without any effect of the response of stomata opening. To prove this, carbon dioxide absorptions were measured and as a result 8 % of the photosynthesis benefit was given with these on/off controls.