Robotic Fruit Harvester Sensors

Strawberries are a very valuable fruit crop in the United States, ranking fourth in production. The state of California leads this charge at 1.4 billion pounds of strawberries, 83% of the nation's total, worth some $800 million (2001). Production costs are estimated $25,000 per acre, of which harvesting is near 63%. Harvest labor costs are more than 40% of total costs Strawberry plants continuously produce new fruit that are harvested throughout the season, so they are not amenable to mass harvesting techniques that disrupt or destroy the plants. Workers spend long periods of time in non-neutral positions picking by hand during harvest. Worker advocates and union management have expressed concern about the long-term effects of these repetitive motions and positions on workers. The US has a shortage of legal residents willing to perform such work, a situation that tends to encourage illegal immigrants who present many legal, ethical and security problems. Nations like Japan are facing extreme shortage of labor and an aging population engaged in agriculture. These factors motivate the development of semi-mechanized systems to reduce human labor required to harvest, sort and pack delicate produce such as strawberries. Strawberries have historically been a difficult fruit to harvest via machine because: 1) Their cultivars do not ripen at the same time or ripen after being picked, thus requiring multiple harvesting passes and 2) Many of their ripe fruit sag to the ground beneath foliage, 3) The berries are damaged easily during handling and 4) The berries do not necessarily cap easily and facilitate detachment of the fruit from the plant. By allowing mechanical harvesting of strawberries farmers will be able to reduce the number of seasonal workers and benefit from increased efficiency.