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Abstract
India is the third largest producer of coconut in the world. Usually all over India conventional harvesting method are used. It is very difficult to climb a coconut tree manually due to structure and the contour of the tree. Generally trees have branches onto which a person can climb and extract fruits but not in the case of trees like coconut tree, areca nut, palm tree, where there are no branches for support. Due to the risks involved, nowadays farmers are hesitating to climb the coconut tree to extract coconuts. Even agricultural workers employed for coconut harvesting hesitate to do the job because they suffer from musculosketal disorders in the long term. The number of workers who can do this job is decreasing day by day. Hence there is need for a machine which can do this job in the place of humans. The robot is a tree climbing robot, design specifically to harvest coconut quickly, safely and efficiently. This robot is to be controlled remotely from the ground, and the operator can see what is happening on top of the tree on his remote display. The robotic arm with the axis of freedom is to be design in such a way that camera can be mounted on either side or top of the robot head. The aim of designing the robot is to provide an automatic machine with reliable monitoring, safety, better efficiency and reduced environmental impact which will support the coconut industry of India.
Introduction
Coconut is one of the cash crops in India. India is among the top players in production of coconut in the world. Coconut harvesting is traditionally carried out by men who belong to economically lower-class society. As the literacy rate increases, and awareness about the high paid job opportunities increases, which leads to the shortage of human coconut tree climbers. As these men usually do not have any insurance coverage, any accidents while climbing the trees would affect the entire family. In such situation there is genuine need to develop an automatic coconut tree climbing and harvesting robot to support coconut industry in India.The conventional way of harvesting is by climbing the coconut tree and cutting it.Because of the risks involved many methods have been developed. There are many methods to climb a tree, one of them is mechanical aid. Another method is to use a robot for climbing and cutting. The recent technology in the field of robotics has reached to a level where we can design variety of robotic system which can do various kinds of tasks like picking and placing, cutting, climbing, flying, etc.Our current research is to develop an autonomatic coconut tree climbing robot which is safe, efficient, easy to operate, and equipped with auto-fastening mechanism to climb a tree of varying diameter.An autonomous climbing algorithm is used to guide the robot. The design of an autonomous robot is to climb the tree in a vertically upward direction.
Problem Statement
Coconut production has a significant influence on the economy of India. But due the risk involved in climbing, there is shortage of tree climbers which is adversely affecting the economy of the country.There are many mechanical models present in the market for coconut tree climbing. These mechanical models requires human being for climbing a tree, but only trained person climb using such machines. Hence the existing techniques are not sufficient to solve the problem of unavailability of workers for coconut harvesting. Thus, there is genuine need to develop a robot with reliable monitoring, safety, greater efficiency and reduced environmental impact which will support the coconut industry of India.
Literature review
Lot of work has been done on the tree climbing robot up till now. Many types of robots had been invented. A literature study is done to understand the mechanism of various types of climbing robots. Literature work is also done on various mechanism that are used for arm and inspection of coconut.
Mani A, Jothilingam A [1] discussed about the development and fabrication of a tree climber and harvester. It consists of two mechanisms. One for climbing and another for harvesting. They designed an octagon shaped chassis where wheels at specific intervals were provided. The proposed design by Mani and Jothilingam had the location of centre of mass of the device outside the tree and it fused both spiral and straight climbs. An arm was provided in order to fulfill the harvesting requirement. The bunch of nuts is located by a camera which is fixated to the arm. The cutting is done by a saw after a clear view of the nuts is obtained. The entire mechanism was controlled by remote control. They discussed about the hardware setup and controlling units were designed.
Rajesh Kannan, Megalingam, R Venumadhav, Ashis Pavan K, Anandkumar Mahadevan, Tom Charly Kattakayam, and Harikrishna Menon T, [2] analysed various models of climbing and harvesting devices. Safety, reliability, ease of use, cleaning the tree tops, spraying pesticides were given prior importance. They designed a system that can be controlled by anyone. The designed prototype responds to human gestures with negligible gap in the response time. A prototype of the arm was designed and tested against human gestures and found successful. Their machine was designed to consume less power, so longer working hours doesnt affect the power consumption.
Methodology
A. Transmitter Block
The user can control the robot through mobile application which is specifically designed for the system.For connection establishment the mobile WiFi gets connected to the receiver.The application is user friendly, the internal architecture required for mobile application will process the user input and its transmitted though the Wi-Fi (wirelessly) to the receiver end.
B. Receiver Block
The received signal from transmitter through the wireless device module (ESP32 Wi-Fi module) is interfaced with microcontroller.Microcontroller reads all command signals from Wi-Fi which the user sends via a mobile application. As per users command the microcontroller takes action to the all interfaced peripherals.
The block diagram is divided into following sections:
- Main control unit Every system has a main control unit to process its all tasks. This control unit takes input from the user. The microcontroller is the main control unit of the proposed system. It takes input from the sensors and perform various tasks depending on the input . The microcontroller controls the system according to the sensors signal and performs the operation.
- Wi-Fi module The Wi-Fi module is a wireless device which is interfaced with the microcontroller. This module is the main source of the system. It takes multiple inputs from the user and gives it to the microcontroller for processing. The wi-fi module has an onboard camera which helps to detect coconut.
- Motor driver- To drive the motor or any load, one driver module is needed. This motor driver controls the speed of motor and drives the motor. This is two channel motor driver which can provide forward and reverse movement of the motor.
- Sensors- The ultrasonic sensors are used, to calculate distance from the object so as to prevent any damage to the system. The ultrasonic sensor at the top will prevent the machine from moving forward in upward direction. Similarly, the sensor at the bottom will make sure that machine will not hit the ground while coming in downward direction.
- Camera The camera unit is used to detect the position of coconuts. It will help the operator to give proper instructions to the arm mechanism. The camera is attached at top of the ARM, where the cutter is located.
- Battery- Battery unit is providing life to the system. It will give power to the microcontroller, Wi-Fi module, motor driver and all other peripherals of the system. The source is DC. The voltage of battery is 12Vdc.
FLOW CHART
The battery is main unit of the system. All operation depends on the battery power. Hence, battery is the main concern in the system. If the battery is charged completely, the system works according to the operation. But if the battery is drained, then the system is disturbed and does not complete its tasks. It is necessary to keep the battery completely charged. If it is not then the user gets alert through LED and the user can know about charging status. If the battery is charged then the system will wait for the user command. User can provide the next task to the microcontroller via the transmitter. In case system does not respond according to the user command, then the system will alert to user. The all processes worked well according to user command, the robot goes up through the motor. The robot should continue to run till ultrasonic sensor sends the signal to the microcontroller. If the distance is more than pre-determined distance from the top, the motor should continue to run in an upward direction otherwise the motor stops. Now, the user sends next command to
the system for opening arm mechanism and camera will turn ON. The camera helps user to inspect the coconut and helps the arm to move towards the coconut.Once the coconut is detected, the cutter is turned ON through the user command and the coconut branch is completely cut by cutter saw. The cutter saw is nothing but a grinder machine whose speed is high due to torque motor. The woodcutter saw clade can be attached on the motor shaft. After cutting coconut according to command, the cutter will stop and the arm goes back to the original position. The motor will turn ON and it will start moving downwards. The ultrasonic sensor again reads the distance from the ground surface and sends signal to the microcontroller. The microcontroller takes action according to the distance. Till the distance is not minimum the robot continues downward movement. The bottom sensor helps to prevent the robot from hitting the ground surface. The robot will perform all the operations according to the flowchart of the project.
SOLIDWORKS DESIGN OF PROJECT MODEL
We have designed an hexagonal shapped system in this we have used six nylon rubber gripped wheel through which the robot moves in upward and downward direction.
The model works on the following mechanisms:
1) The sliding mechanism
This mechanism works through sliding rods drilled in the frame with a helical spring. As the machine moves upward, the diameter of tree decreases, hence the slider mechanism slides inside due to the tension induced by the spring and retracts again to the main position as the robot slides towards the bottom of the tree due to increasing diameter.
2) Climbing mechanism
The robot climbs up on the tree due to the high torque motors and wheels. The wheels are designed such that it will provide maximum grip to the surface of the tree and hence it will help the robot to hold itself and climb upwards with required friction.
3) The cutter mechanism
In this mechanism the arm is attached at the top most region of the robot.The arm is rotated by using a motor and a wheel. The arm consists of two link rods, a high rpm motor and a cutter blade fixed on the shaft of the motor.
MOBILE APPLICATION
The mobile application for the Android operating system which is focused on manual control using wireless control. The controlling device may be any android based Smartphone/tab etc. having an android OS. The android controlling system provides a good interactive GUI that makes it easy for the user to control the robot. The transmitter uses an android application required for transmitting the data. The receiver end reads these commands and interprets them into controlling the robot. The android device sends commands to move the robot in upward, downward and controlling the arm in 3-axis direction. The communication between android device and receiver is sent as serial communication data. The microcontroller program is designed to move the motors through a motor driver IC, as per the commands sent by android device.
CONCLUSION
Development in recent technologies has introduced radical changes to the agriculture. The main aim is to bring more robots and artificial intelligence into agriculture. These technologies enables greater efficiencies, lower prices, increased worker safety, reduced environmental and ecological impact.Our model is to provide a viable alternative for coconut cutting and harvesting as the percentage of manual cutters is decreasing day by day. Also, it is an eco-friendly machine with better efficiency and safety.From all the research work and calculations, we can conclude that the robot will climb the tree and cut the coconut, reducing the human work unit at the same time will increase the efficiency by cutting more coconut compared to humans.We have developing a novel climbing robot which can move in forward and backward direction. Also it can remain stationary based on its own weight.
References
- Mani A, Jothilingam A, Design and Fabrication of Coconut Harvesting Robot: COCOBOT , International Journal of Innovative Research in Science, Engineering and Technology, Volume 3, Special Issue 3, March 2014
- Rajesh Kannan, Megalingam, R Venumadhav, Ashis Pavan K, Anandkumar Mahadevan, Tom Charly Kattakayam, and Harikrishna Menon T, Kinect Based Wireless Robotic Coconut Tree Climber , 3rd International Conference on Advancements in Electronics and Power Engineering,January 2013
- P. Mohankumar, D. Anantha Krishnan and K. Kathirvel, Development of ergo refined coconut tree climbing device , African Journal of Agricultural Research, Volume 8, November 2013
- Rahul V, Sebin Babu, Sameer Moideen CP, Vineeth VP, Nikhil Ninan, ‘Semi automated coconut tree climber’, International Journal of Research in Engineering and Technology, November 2014
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