A selective tea-plucking robot, built for CDAC and proven in the field

Tea plucking is manual, seasonal and labour-constrained, and selective plucking, taking only the right leaves, demands precise and repeatable positioning. The Centre for Development of Advanced Computing (CDAC), Kolkata, needed a gantry manipulator with a cutter that could pluck, hold and drop tea leaves onto a conveyor, take leaf positions from a vision system over an industrial protocol, and survive real field conditions mounted on a hydraulic vehicle.

We designed and built the manipulator to a full technical specification and integrated it in the field.

• A 3-axis gantry manipulator roughly 1600 × 1200 × 1000 mm, with X, Y and Z electrical actuator strokes of 1300 mm, 1100 mm and 400 mm
• A pneumatic cutter that cuts, holds and drops leaves onto a conveyor beneath the gantry
• Servo-motor actuators with encoder feedback on every axis
• Leaf positions fed to the controller from a single-board computer over MODBUS TCP/IP
• A waterproof build to withstand field conditions, powered from a 24V battery pack, mounted in front of a hydraulic vehicle at 1.5 m
• On-site trials at the Tocklai Tea Research Institute in Assam, integrating CDAC's software with the system across repeated visits

The system meets the throughput target of at least 40 leaves a minute, was proven in the field at Tocklai, and was delivered for CDAC Kolkata with the software integrated.