| We present designs, theory and the results of fabrication and testing for a novel parallel microrobotic assembly scheme using stress-engineered MEMS microrobots. The robots are 240--280 mum x 60 mum x 7--20 mum in size, each robot consist of a curved, cantilevered steering arm, mounted on an untethered scratch drive actuator (USDA). These two components are fabricated monolithically from the same sheet of conductive polysilicon, and receive a global power-delivery and control signal through a capacitive coupling with an underlying electrical grid. However, only a single, global control signal can be used to maneuver multiple stress-engineered microrobots within the same operating environment.;We show how only a single control and power delivery signal can be used to maneuver multiple microrobots to implement microassembly. We classify the robots into microrobot species based on the design of their steering arm actuators. The microrobot species are further classified as independent if they can be maneuvered independently using the global power and control signal. We show that microrobot species are independent if the two transition voltages of their steering arms, i.e. the voltages at which the arms are raised or lowered, form a unique pair. We present control algorithms that can be applied to groups of independent microrobot species to direct their motion from arbitrary non-deadlock configurations to desired planar microassemblies.;We present designs and fabrication for four independent microrobot species, each with a unique transition voltage. The fabricated microrobots are used to demonstrate directed assembly of five types of planar structures from two classes of initial conditions, thereby validating our planning and control algorithms. We demonstrate an average docking accuracy of 5 mum, and use self-aligning compliant interaction between the microrobots to further align and stabilize the intermediate assemblies. The final assemblies match their target shapes on average 96%, by area. |
