Coconuts have long been renowned for their health benefits.
They are also used in a wide variety of products including soap and cooking oil – but harvesting them is no easy task.
Specially trained harvesters must risk their lives by climbing trees up to 15m high to hack off just one bunch of coconuts.
Now researchers in India have developed a robot, named Amaran, that could one day reduce the need for humans to take on the risky job of climbing coconut trees.
Along with lab tests, they compared Amaran’s ability to harvest coconuts to that of a 50-year-old veteran harvester. Though the man was faster than the robot, he could not match the robot’s endurance.
To climb, Amaran relies on a ring-shaped body that clasps around trees of varying diameter.
The robot carries a control module, motor drivers, a power management unit, and a wireless communications interface. Eight wheels allow it to move up and down a tree, as well as rotate around the trunk. Amaran is controlled by a person on the ground, who can use an app or joystick system to guide the robot’s movements.
Usually only male workers take up this tree climbing job. But Amaran can be operated by anyone irrespective of gender, physical strength, and skills.
Once Amaran approaches its target, an attached controller unit wields a robotic arm with 4 degrees of freedom to snip the coconut bunch. As a safety feature, if Amaran’s main battery dies, a backup unit kicks in, helping the robot return to ground.
“No two coconut trees are the same anywhere in the world,” he explains.
“Each one is unique in size and has a unique alignment of coconut bunches and leaves. “So, building a perfect robot is an extremely challenging task.”
While testing the robot in the lab, Megalingam and his colleagues found that Amaran is capable of climbing trees when the inclination of the trunk is up to 30 degrees with respect to the vertical axis. Megalingam says that many coconut trees, especially under certain environmental conditions, grow at such an angle.
Next, the researchers tested Amaran in the field, and compared its ability to harvest coconuts to the human volunteer. The trees ranged from 6.2m to 15.2 m in height.
It took the human on average 11.8 minutes to harvest one tree, whereas it took Amaran an average of 21.9 minutes per tree (notably 14 of these minutes were dedicated to setting up the robot at the base of the tree, before it even begins to climb).
But Megalingam notes that Amaran can harvest more trees in a given day.
For example, the human harvester in their trials could scale about 15 trees per day before getting tired, while the robot can harvest up to 22 trees per day, if the operator does not get tired. And although the robot is currently teleoperated, future improvements could make it more autonomous, improving its climbing speed and harvesting capabilities.
“Our ultimate aim is to commercialize this product and to help the coconut farmers,” says Megalingam.