The work of picking strawberries is tedious and exhausting. It requires thousands of poorly paid workers to spend hours walking through strawberry fields, bending over to pick the ripe fruit, examining what can and cannot be picked, using their fingers dexterously to pull the fruit out without damaging the plant, and so on.
Given that it is such a demanding and poorly paid job, it is increasingly difficult to find people willing to do it, and many farmers have seen the fruit rot on their land when they fail to pick it. In California, for example, farmers apparently lose about a fifth of their crops due to lack of labour.
A robot, under the name of Ceres, created by a California-based startup Traptic (the largest strawberry-producing state in the United States) promises to remedy this situation.
A difficult task to automate
Automation has already been applied to several different staple crops. Crops such as wheat and corn are routinely harvested by machines. Strawberries and other fruits, however, present a unique challenge: they are too delicate for most machines.
The biggest problem with strawberry picking is that it requires so many different skills and adapts to so many changing situations that it is an extremely difficult process to automate. Only one human being is capable of doing this with sufficient skill.
However, Traptic has managed to program artificial intelligence algorithms that are already capable of performing this task with equal skill to humans. The device created by Traptic is a robot that can be installed on a small tractor and that, through its visual recognition algorithms, can identify the fruits to be harvested from the foliage.
To check whether the strawberry is ripe enough, the algorithms also check its colour. The vision system uses 3D cameras and neural networks to also be able to determine the position with a millimetre margin of error. Finally, if the fruit is OK, then a mechanical arm picks it up with enough skill not to damage either the plant or the strawberry.
At the tip of the robot’s arm, there is also an important element: a gripper. This customised clamp is one of the most unique elements of the system, as it is rigid enough to pull the burs out but soft enough not to crush them in the process. The metal base of the claws is reinforced by rubber bands that are elastic enough to adapt to the irregular shapes of the fruit.
Currently, Ceres is being tested by growers in Northern and Southern California, different climates that allow them to evaluate its ability to grow strawberries all year round.
Other companies working on robotic strawberry harvesters include Agrobot, CROO Robotics and Advanced Farm Technologies (AFT), which has also marketed its T-6 strawberry picking robot and is already in use in California. For its part, Traptic is planning to go beyond strawberries: it wants its algorithms to work on all kinds of crops, regardless of how difficult they are.