Precision-Based Robot Kinematics Design for Microassembly Applications

The kinematics of a robotic manipulator, including the type of joints, actuators, and other geometric parameters significantly affects its precision (or positioning uncertainty) at the end-effector. Modeling and prediction of these uncertainties can provide useful insight and serve as design guidelines for precision manipulators that are used in micro and nanomanufacturing. Of particular interest are micro scale assembly scenarios where the tolerance budgets are stringent and precision requirements are high, but there is little space for extensive sensor feedback due to a small work volume. In this paper, we investigate the effect of parametric uncertainties in a serial robot chain on overall positioning uncertainty at the end-effector. Two types of errors are considered: static errors due to misalignment and link parameter uncertainties, and dynamic errors due to inaccurate motion of individual links. Using uncertainty metrics we compare the precision of several different robot kinematic chain configurations.