An agricultural robot is a robot designed to perform certain tasks in agriculture and horticulture. The main application area for robots in agriculture is harvesting. A possible emerging application concerns robots or drones designed to perform crop weeding.
General
Fruit harvesting robots, autonomous (driverless) tractors and sprayers, and sheep shearing robots are designed to replace labor.
In most cases, a large number of factors must be considered (e.g., the size and color of the fruit to be picked) before a task is committed. Robots can be used for other tasks in horticulture, such as pruning, weeding, spraying pesticides and monitoring.
Robots can also be used in the field of animal husbandry (livestock robotization), in applications such as automatic milking, washing and castration of animals. This type of robot has many advantages for the agricultural sector, including better quality of fresh products, lower production costs and less need for labor.
Design
The mechanical design of an agricultural robot consists of three main components: the end effector, the manipulator arm and the gripper. Several factors must be considered in the design of the manipulator arm, including the task to be performed, economic efficiency and the movements required. The end effector can influence the market value of the fruit and the design of the grabber depends on the type of crop being harvested.
End effectors
In an agricultural robot, the end effector is the device at the end of a robotic arm that is used to perform various agricultural operations. Several types of end effectors have been developed.
At a winery in Japan, end effectors are used to perform actions such as harvesting, bunch thinning, spraying, and bagging. Each end effector is designed according to the nature of the task at hand and the characteristics of the fruit (shape, size, etc.). For example, the end effectors used for grape harvesting were designed to grip, cut and push the grapes.
Thinning is another operation performed on grapes that is used to improve their market value, increase berry size and facilitate cluster formation. An end effector for thinning has three elements: upper, middle and lower. The upper element has two plates and a rubber that can open and close. The two plates grip the grapes to cut the stem and extract the bunch of grapes. The middle element has a needle plate, a compression spring and another plate with holes distributed on its surface. When the two plates come together, the needles pierce the grapes. Then, the lower element has a cutting device that can cut the bunch to normalize its length.
For spraying, the effector consists of a spray nozzle that is attached to a manipulator arm. In practice, growers want to ensure that the chemical liquid is distributed evenly throughout the bunch. Thus, the design must allow for even distribution of the chemical by having the nozzle move at a constant speed while keeping it away from the target.
The final step in grape production is bagging. The bagging end effector includes a bag feeder and two mechanical fingers. In the bagging process, the feeding system consists of slots that continuously feed bags to the fingers in an up and down motion. When a bag is inserted between the fingers, two leaf springs at the top of the bag hold it open. The bags are made to hold the grapes. Once the bagging process is complete, the fingers open and release the bag. This closes the leaf springs, which seals the bag and prevents it from opening again.
Clamp
The clamp is a gripping device that is used for harvesting the target crop. The design of the pliers is based on simplicity, low cost and efficiency. Thus, the design usually consists of two mechanical fingers that are capable of synchronized movements when performing their task. The technical features depend on the assigned task. For example, when the operating mode is to cut plant parts for harvesting, the gripper is equipped with a sharp blade.
Manipulator arm
The manipulator arm is a mechanical device that allows the gripper and end effector to navigate their environment. It consists of four parallel rods that maintain the gripping position and height. The manipulator can also use one, two or three pneumatic actuators. Pneumatic actuators are motors that produce linear or rotary motion by converting compressed air into energy. The pneumatic actuator is the most efficient for agricultural robots because of its high power-to-weight ratio. For the manipulator arm, the most cost effective design is the single actuator configuration, although this option is the least flexible.
Applications
Robots have many applications in agriculture, whether as a tool platform in field crops or in vineyards or market gardening, which are labor-intensive subfields.
A case of large-scale use of agriculture robots is the milking robots. These are widely used on British dairy farms because of their efficiency and lack of travel requirements. According to David Gardner (chief executive of the Royal Agricultural Society of England), a robot can perform a complicated task if it is repetitive and if the robot can remain stationary. In addition, robots that work on repetitive tasks (such as milking) perform their role with great consistency and task-specific adaptation.
Another application area is horticulture. One horticultural application is the RV 100, developed by Harvest Automation Inc. This robot is designed to transport potted plants in a greenhouse or outdoor horticultural operation. The RV 100’s functions in handling and organizing potted plants also include spacing, collecting and consolidating capabilities. Advantages of using the RV 100 for this task include high accuracy of pot placement, autonomous operation outdoors and indoors, and reduced production costs.
Robot employment has been growing in recent years with a 22.8% increase in 2020 worldwide. In 2019, investment in agricultural robotics reached $179 million.
Source: wikipedia.org