Rotatory microgripper based on a linear electrostatic driving scheme

Nonlinearity is a common problem for many types of microgrippers and can make it difficult to achieve high precision control over the entire input variation range. This paper presents a linear electrostatic driving scheme consisting of a bidirectional rotary actuator and a divider circuit for microgrippers. Different from the conventional approach, the rotary actuator in the linear electrostatic driving scheme is driven by two differential driving voltages provided by the divider circuit. Using the linear electrostatic driving scheme, the displacement of the microgripper's jaw is proportional to the resistance of potentiometer of the divider circuit. The experiment shows that the jaw gap of the microgripper varies from 0 to 220 μm when the potentiometer rotates from 300° to 3240°. The nonlinear error of the rotatory microgripper is 0.14%, which is an improvement of over 100 times compared with the conventional driving scheme. In addition, a pick–release grasping experiment on glass spheres is performed to prove the capability of the rotatory microgripper in handling micro objects.