Design and analysis of a novel 3-DOF spatial parallel microgripper driven by LUMs

• A novel 3-DOF flexible hinge-based spatial parallel micromanipulator is proposed.
• The micromanipulator has a two fingers design based on the use of chopsticks.
• We establish the kinematic model and calculate the motion stroke of its end-effector.
• Driven by linear ultrasonic motors, the workspace of the micromanipulator is enlarged meanwhile the displacement resolution is nano-sized.

A novel 3-DOF microgripper driven by Linear Ultrasonic Motors (LUMs), with nanometer positional accuracy and an operational space in the millimeter scale is proposed. A two-fingers design method based on a chopstick-like structure is presented. The operational mechanism is illustrated to demonstrate how the microgripper works. Based on the spatial parallel mechanism with joints formed by right circular multi-axis flexible hinges, the kinematic model as well as the relationship between output and input displacement are derived. The maximum displacement of the manipulation end-effector is calculated and an error analysis is conducted. A series of experimental results indicate that the reachable operational workspace of the microgripper is a 20 mm height cylinder with the major-axis of 2.3415 mm and the minor-axis of 2.1178 mm, while the displacement resolution is 100 nm. Successful experiments on gripping a single shrimp embryo demonstrate that the microgripper has good performance in gripping micro-objects.