Design and analysis of four-bar linkage transplanting mechanism incorporating compliance linkage

Abstract

Importance of the work: A novel transplanting mechanism was developed and tested,
combining a four-bar linkage with a compliance linkage, enabling continuously adjustable
planting distances without requiring mechanical reconfiguration.
Objectives: To design and test a four-bar linkage transplanting mechanism incorporating
a compliance linkage for precision agriculture.
Materials and Methods: A transplanting mechanism was developed and mounted on
a mobile crane. Kinematic modeling, kinetic analysis and spring-stiffness calculations
were conducted to ensure a zero-speed planting condition (λ ≈ 1). Field tests were
performed using five vegetable types.
Results: The mechanism achieved high precision in planting: cabbage (mean spacing
= 31.5 cm, coefficient of variation, CV = 4.56%), lettuce (25.8 cm, CV = 4.31%),
green onion (10.2 cm, CV = 3.65%), sweet chard (20.7 cm, CV = 4.12%), and Chinese
celery (15.3 cm, CV = 3.89%). The qualified transplanting rate exceeded 95% for all
crops. The system achieved a planting rate of 828 seedlings/hr/row—nearly three times
faster than manual transplanting.
Main finding: This new mechanism enables infinitely variable planting distances,
allowing it to accommodate nearly any vegetable type—an adaptability that conventional
transplanting systems lack.