Journal of Mechanisms and Robotics · 2013 · 159 citations · 36 references
EngineeringMechanical EngineeringMechatronics EngineeringActuatorsRobot KinematicsSensorsActuation SystemsActuator DesignActuator DynamicsActuator IntegrationManipulator DynamicsNanomechanicsConstraintsControlsDisplacement SensingDynamic Model DerivationDynamic Model IdentificationLarge-displacement ActuationNanopositioningNanopositioning Systems
Nanopositioning systems struggle to combine >1 mm motion range with <10 nm precision, as component limits typically confine current devices to about 100 µm per axis. This study introduces a new XY nanopositioning layout that integrates a parallel‑kinematic flexure bearing, large‑stroke actuators, and sensors to achieve a large motion range. The system employs a parallel‑kinematic XY flexure bearing that decouples axes, isolates actuators, and supports end‑point sensing, and a dynamic model is developed and verified, and the device is fabricated, assembled, and tested. The design delivers a 10 mm × 10 mm motion range, reveals dynamic nonlinearities from large flexure displacements, and preliminary closed‑loop tests demonstrate both its potential and remaining challenges.
Achieving large motion range (>1 mm) along with nanometric motion quality (<10 nm) simultaneously has been a key challenge in nanopositioning systems. Practical limitations associated with the individual physical components (bearing, actuators, and sensors) and their integration, particularly in the case of multi-axis systems, have restricted the range of currently available nanopositioning systems to approximately 100 μm per axis. This paper presents a novel physical system layout, comprising a bearing, actuators, and sensors, that enables large range XY nanopositioning. The bearing is based on a parallel-kinematic XY flexure mechanism that provides a high degree of geometric decoupling between the two motion axes by avoiding geometric over-constraint, provides actuator isolation that allows the use of large-stroke single-axis actuators, and enables a complementary end-point sensing scheme using commonly available sensors. These attributes help achieve 10 mm × 10 mm motion range in the proposed nanopositioning system. Having overcome the physical system design challenges, a dynamic model of the proposed nanopositioning system is created and verified via system identification. In particular, dynamic nonlinearities associated with the large displacements of the flexure mechanism and resulting controls challenges are identified. The physical system is fabricated, assembled, and tested to validate its simultaneous large range and nanometric motion capabilities. Preliminary closed-loop test results, which highlight the potential as well as pending challenges associated with this new design configuration, are presented.
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