Multi-mode hybrid micro-gripper for micro-manipulation and micro-assembly

This work presents the design, implementation, and validation of a multi-mode hybrid micro-gripper for robotic micro-manipulation and assembly in smart manufacturing applications. The device combines vacuum-and friction-based grasping technologies in a compact, lightweight design, enabling accurate and reliable handling of micro- and meso-scale Surface Mount Technology (SMT) components. The system supports three operational modes: friction, vacuum, and a hybrid grasping that simultaneously engages both technologies. The gripper features a modular architecture and can be manufactured with additive-manufactured technology and low-cost commercial components. Each finger of the friction grasping is actuated by a miniature linear stage equipped with a stepper motor, controlled through a closed-loop motion algorithm based on a PID regulator and a linear potentiometer for position feedback. A two-state control manages the vacuum supply to the suction cup and the pneumatic cylinder, which enables hybrid grasping. All three operational modes were experimentally validated, demonstrating high accuracy and reliability in manipulating different SMT components with dimensions in the range of 0.5 × 0.5 mm to 8 × 8 mm. Extensive experimental tests were performed for friction grasping to assess positioning accuracy, motion synchronisation, disturbance rejection, and stall detection, achieving positioning errors below ± 50 µm and synchronisation errors under 30 ms.