A General Kinematic Modeling Framework for a 3D Compliant Micromechanism

Exploiting engineering compliance in microrobotics has been a breakthrough approach for navigating well-known tradeoffs related to precision, fabrication, and control challenges at small scales. However, modeling of compliant, multi-body, 3 dimensional microrobots is considerably more difficult than traditional rigid-body robot kinematics. In this paper, we formulate a kinematic modeling methodology applicable to a broad class of compliant microrobots. Such models can be used prior to fabrication to evaluate mechanism dexterity, precision and sensitivity to dimensional tolerances. They can also be used for microrobot visualization, control synthesis and for fast parametric optimization. We exemplify our approach by modeling the AFAM, an Articulated Four Axes Microrobot, constructed via 3D microassembly from Micro Electro Mechanical System (MEMS) compliant building blocks. The AFAM is a novel mm-scale microrobot designed for nano-positioning tasks in future wafer-scale microfactories. We derive the kinematic model of the AFAM using a computationally scalable constraint optimization approach that can be used equally effectively for both forward and inverse kinematics. Simulation results using the robot operating system (ROS) programming framework are presented in the paper.