Design and Control of a Piezoelectrically Actuated Fast Tool Servo for Diamond Turning of Microstructured Surfaces

Abstract

This paper reports on the mechanism design, dimension optimization, closed-loop control, and practical application of a piezoelectrically actuated fast tool servo (FTS) for the diamond turning of micro-structured surfaces. With the mechanism, a finite element based analytical model is developed to theoretically relate the working performance with its structural dimensions. Considering its application for micro/nanocutting, the structural dimensions of the mechanism are deliberately determined through evolutionarily optimizing a comprehensive objective. To ultra-finely track the cutting trajectory with a high bandwidth, a PID controller together with the dynamics inversion based feedforward compensation is optimally designed with assistance of the Nyquist diagram, and a disturbance observer is further employed to compensate for the inherent hysteresis nonlinearity as well as external cutting force disturbances. Both open-loop and closed-loop experimental tests on the prototype suggest that a stroke of 15 µm and a closed-loop bandwidth of 1730 Hz are achieved. Taking advantage of the newly developed FTS, two typical micro-structured surfaces are ultra-precisely turned, well demonstrating the effectiveness of the FTS.

Actuator Saturation Compensation for Fast Tool Servo Systems With Time Delays

“…First, we conduct the closed-loop step tests to verify the servo performance in the absence of actuator saturations. For comparison, the existing methods for FTS systems, including a traditional H ∞ controller, a PID controller [30] and a compound control structure composed of PID with feedforward compensator and a disturbance observer (denoted as PID+FC+DOB) [31], are also designed for the FTS system. As clearly shown in Fig.…”

Fixed-Time Third-Order Super-Twisting-like Sliding Mode Motion Control for Piezoelectric Nanopositioning Stage

“…The last decades have witnessed the increasing popularity of piezoelectric actuators among nanopositioning platforms, which provide several advantages including ultra-fine resolution, quick response speed, large energy density, and no backlash. Such piezoelectricdriven nanopositioning devices exhibit a variety of applications, such as atomic force microscope [1,2], biological manipulation [3] and precision machining [4]. Nevertheless, the intrinsic hysteresis of piezo-driven stages, which is amplitude-and rate-dependent, leads to challenges of its precise positioning.…”

Analytical Compliance Equations of Generalized Elliptical-Arc-Beam Spherical Flexure Hinges for 3D Elliptical Vibration-Assisted Cutting Mechanisms

“…Enormous amounts of attention have been paid to how to fabricate these surfaces with high efficiency and high accuracy by ultra-precision manufacturing. Compared with conventional mechanical forming methods, ultra-precision fast tool servo (FTS) [5][6][7] and elliptical vibration-assisted cutting (EVC) [8,9] are more effective ways to meet these requirements for surface texturing of difficult-to-machine materials. Since the flexible hinge can realize the transmissions of motion, force and energy through the elastic deformation of its flexible unit and has the advantages of high transmission accuracy, no friction, no lubrication, no gap, etc.…”