Design and Development of Robot for Harvesting Cotton Bolls

Abstract

Most of the cotton crop in India is harvested by handpicking, by women workers in general. Manual harvesting is very labour intensive and also a difficult activity involving drudgery. Cotton cultivation in India occupies a big share in commercial crops and is facing a major problem of harvesting labour. Objective of this work is to design and develop a cotton boll harvesting robot which is suitable for Indian farming practices meeting the needs of small and medium scale farmers. Field study and detailed literature review has been carried out to understand the cultivation of cotton crop, current harvesting practices and harvesting robots developed for other crops. Data collected through field visits was used to develop the cotton plant canopy and boll distribution within the canopy. This helped to decide the harvesting task space, maximum reach, and cotton-picking trajectories for the proposed cotton boll harvesting robot. Based in these requirements, specifications of the proposed cotton-picking robot were developed. Different conceptual robot designs involving standard arm configurations were developed to meet the specification and the best was selected considering compactness, weight, operational speed and control complexity. The selected design is a three link TRR configuration robot with mobile base equipped with vacuum type end-effector. A 3D model of the Cotton boll harvesting robot was created using SolidWorks software and the model was simulated in ADAMS software to validate its working and extract joint torques and other results. Detailed design of components and sub- systems was carried out to meet the design requirements of cotton boll harvesting robot. Designed components were fabricated as per requirements, sub systems were integrated and assembled. The developed cotton boll harvesting robot was integrated with the controller, programmed and proved for its work successfully. The developed robot has been tested in controlled laboratory conditions and it is capable of harvesting cotton bolls, with an average speed of 60 sec to pick 10 cotton bolls. The overall weight and cost of the system can be reduced further through optimization of sub-systems/ components.  Also, future research has to focus on implementing image processing and testing of the robot in outdoor farming conditions. By replacing the dc motors used presently with servo motors, high precision and accuracy of the system can be achieved.