(AP) — A lettuce thinner, a pruner for wine grapes, a strawberry harvester — they’re examples of a new generation of machines that target the last frontier of agricultural mechanization.

Fruits and vegetables destined for the fresh market, not processing, have thus far resisted mechanization because they’re sensitive to bruising. But researchers are now designing robots for these crops by integrating advanced sensors, robotic hardware and GPS technologies.

Though they cost millions of dollars, farmers say, the robots could provide relief from recent labor shortages, reduce costs, increase quality and yield a more consistent product.

Farmworker advocates say mechanization would lead to workers losing jobs, growers using more pesticides and the food supply becoming less safe. Most ag robots won’t be commercially available for at least 10 years.