Model development and boundary interaction force control of a piezoresistive-based microcantilever

Abstract

SUMMARY Robots with micro- and nanoresolution of motion are becoming more practical and useful in many precision manufacturing processes and industries such as medical instruments and imaging tools. Apparently, the most important features of these devices are their precision and durability. As accuracy increases, more delicate tasks may be performed. Along this line, a spatial micromanipulator with three revolute–revolute–prismatic joints while equipped with nanometer motion resolution is considered here. At the end of the micromanipulator, a piezoresistive-based microcantilever operates as a force sensor to quantify the amount of the strain generated in the microcantilever and transduces it into a proper voltage for force sensing applications. In terms of the controller design, the value of the produced voltage can further be implemented as the feedback entering into the control loop and making the control unit to produce appropriate signals for manipulating the robot arm. A challenging and important problem is the need to control the applied boundary forces at the contact zone with external objects (specifically the biological samples). The ability to control the interaction force is of most interest today which has numerous applications in precision manufacturing and biomedical engineering. For this purpose, two types of controllers are presented here: a Lyapunov-based proportional-derivative (PD) controller and a robust adaptive (RA) controller. The performance and the stability of these two controllers are examined and discussed thoroughly in this paper so that it can be interpreted that the robust adaptive controller is robust under presence of uncertainties in force tracking control purposes.