Design and experiment of an end-effector for harvesting sweet pepper in compliant obstacle environment

Picking sweet peppers by hand is often time-consuming and laborious. To overcome this, in the current study, we developed an end effector for mechanized and non-destructive harvesting of sweet pepper. The design includes grip modules, shear modules and control systems. Based on the establishment of an approximate mathematical model of sweet pepper fruit and the analysis of the biomechanical characteristics of sweet pepper fruit, a pinch finger was proposed. The proposed mechanism is able to successfully achieve non-destructive and stable fixation of sweet pepper and fruit bunches. Key parameters of peduncles cutting were obtained by the cutting test. A cutting mechanism was then designed to achieve efficient separation of the fruit and fruit stem. The designed end effector achieves precise control through a single-chip microcomputer and multi-sensor integrated control system to achieve mature target fruits. The test results showed that the picking success rate, damage rate and picking time of peppers were 93.3%, 1.6% and 5 seconds, respectively. The end effector designed for sweet pepper picking has a simple and reliable structure, which provides a reference for further research on sweet pepper picking robots.