XY Platform Research Articles

An active disturbance rejection synchronous control strategy based on cross compensation for stepper motor XY platform

In view of the system uncertainty factors and bilateral drive synchronization problems of XY platform driven by stepping motor, on the basis of the mathematical model of single axis servo system, in order to improve traceability and disturbance rejection in X,Y direction, a double loop structure with PID controller as speed loop and active disturbance rejection as position loop is proposed to solve the contradiction between rapidity and overshoot, moreover, an ESO performance analysis method is proposed, and the parameter tuning rules of ADRC is summarized. On this basis, a deviation self-coupling compensation control strategy is proposed to solve the problem of bilateral drive synchronization in axis X direction, and the mechanism and parameter adjusting method of the compensator are studied. The comparative experiment between ADRC+PID+deviation self-coupling compensation and PID+PID+deviation self-coupling compensation, the comparative experiment between ADRC+PID+deviation self-coupling compensation and ADRC+PID are conducted, respectively. Finally, the experiment of synthetic trajectory of X and Y is carried out, the simulation and experimental results demonstrate that the response time of the control strategy proposed in this paper is 0.5 s, which is 0.2 s faster than PID’s, and the disturbance recovery time is 50% of PID control. Therefore, the proposed ADRC+PID+deviation self-coupling compensation control strategy can not only effectively improve the tracking performance of the XY platform system, but also enhance the robustness of the system.

Development of a Novel Flexure-Based XY Platform Using Single Bending Hybrid Piezoelectric Actuator

In this article, a novel flexure-based XY platform using a bending hybrid piezoelectric actuator was proposed, which was inspired by a classical piezoelectric stack-actuated platform. First, the stack-actuated platform was designed, the configuration and working principle of the bending hybrid piezo-actuated platform were illustrated. Then, theoretical analyses were conducted to design the piezo-actuated platform, the finite element method was employed for the static and dynamic analyses, and the prototypes of the two platforms were fabricated. Eventually, a series of tests were carried out to verify the theoretical and simulated results, and to investigate and compare their output characteristics. The experimental results revealed that the proposed piezo-actuated platform could achieve a motion range of 16.48 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> m × 16.84 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> m and the coupling error of less than 0.59%. Furthermore, the hysteresis ratios were about 8.3% and 8.2%, the first-order bending frequencies were 2162 and 2303 Hz in two axes, the displacement resolution was about 4.31 nm, and the steady-state displacement deviations of the point-to-point positioning control both are within ±30 nm in two axes. Compared with the traditional stack-actuated platform, the piezo-actuated platform not only had positive and negative output displacement, but also possessed superior performance, including low cross-coupling, low hysteresis, and high resolution, which was expected to be used in nanopositioning and micro/nanomanipulation.

Research on high-speed and high-precision laser processing algorithm based on macro-micro platform

Aiming at the problem that XY motion platform cannot realize high-speed and high-precision machining simultaneously, a high-speed and high-precision laser processing algorithm is proposed based on the macro-micro structure of laser cutter with a laser galvanometer scanner. The velocity planning of macro platform and composite motion is carried out by applying finite impulse response (FIR) filters three times, and velocity planning of micro platform is obtained by vector subtraction method. The motion decomposition of the macro-micro platform is realized accurately. The macro platform is responsible for large-format movement, and the micro platform is responsible for fast-speed turning. Velocity overlap of adjacent segments is employed to improve the machining efficiency. The constraints are established to determine the overlapping time, so that the algorithm can realize high-speed machining without introducing contour error, and ensure that the velocity, acceleration, and jerk of the macro platform can be processed within the limit range. Experiment and simulation analysis show that compared with using only the XY platform, the total machining time of using the macro-micro platform with the algorithm proposed in this paper is reduced by more than 35%.

A Spatial Deployable Three-DOF Compliant Nano-Positioner With a Three-Stage Motion Amplification Mechanism

This article presents the design, analysis, and prototype test of a novel spatial deployable three-degree of freedom (DOF) compliant nano-positioner with a three-stage motion amplification mechanism (MAM). Inspired by deployable structures, a new design concept, namely monolithically spatial compliant mechanism (MSCM) is proposed to minimize the overall structure. Based on MSCM, a folding operation is employed uniquely by arranging three typical kinds of basic MAM modules with two sets of hooke joints. Due to the spatial structure, the dimensions in horizontal plane is reduced by 60.94%. Furthermore, the proposed nano-positioner demonstrates the simultaneous design of large-ratio amplification mechanism, compact, highly flexible, and assembly-free spatial XY platform with integrated Z platform. Analytical modeling is carried out, and finite element analysis is conducted to optimize the geometric parameters. A prototype is fabricated to verify the performances of the nano-positioner through tests. Experimental results demonstrate that the maximum displacements in $x$ -, $y$ -, and $z$ -axes can reach 177.33, 179.30, and 17.45 $\mu$ m, respectively. The motion amplification ratios in the $x$ - and $y$ -axes can reach 10.19 and 10.30, respectively. Moreover, by adopting proportional-integral-derivative feedback controller, the closed-loop control experiments are conducted. The results show that the motion resolution in three axes can all reach 5 nm. As the MSCM has been verified to be feasible and favorable, it can be anticipated that the design concept will contribute to the multiformity and development of compliant mechanisms.

Design, Modeling, and Experimental Evaluation of a Compact Piezoelectric XY Platform for Large Travel Range.

A novel piezoelectric XY platform driven by a single actuator was presented for a large travel range and compact structure. The actuator operated at the inertial mechanism and moved the output platform step-by-step. A dynamic model of the piezoelectric actuator was established based on the Timoshenko beam theory and Galerkin procedure, which was used to aid the structure design. The dynamic model of the platform system was established based on the dynamic model of the actuator and the LuGre friction model. A prototype was fabricated and its experimental system was established; the total size was 100 × 100 × 93.5 mm3 and the travel range was 15 × 15 mm2. The measured stepper motions agreed well with the simulation results, and the correctness of the dynamic model was confirmed. The proposed platform achieved maximum speeds of 2.13 and 3.11 mm/s along the axes X and Y , respectively, and a carrying capacity of 20 kg was achieved. Furthermore, the closed-loop control experiments, including the positioning resolution and the sinusoidal trajectory tracking, were carried out, and a positioning resolution better than [Formula: see text] and a tracking error rate of 4% were achieved, which revealed the potential of the proposed piezoelectric platform in field of manipulating heavy objects with submicrometer accuracy and large travel range, especially for some specific fields including microparticle manipulation, ultraprecision manufacturing, and optical device posture adjustment where large travel range, high accuracy, and multidimension are expected.

Implementation of Network Motion Systemusing RTEX Network for XY Gantry

Recently, the weapon systems are more and more complex and the demands for handling and maintaining these complex systems effectively are increased. For this reason, industrial control network had been developed for many years and the needs for the development of a totally networked automation environment are raised. To meet these requirements, networked motion control systems tend more and more to replace the traditional solutions. In this paper, the XY platform motion control system employing RTEX (Real Time Express) network which is one of the Ethernet based vender-oriented industrial networks is tackled. The network motion controller which generates motion profile and outputs the pulse train is implemented and is applied to XY platform. As results, it is shown that the proposed network motion controller works properly to control the XY platform and monitors the system easily through network.

Position precision improvement throughout controlled led paths by artificial vision in micromachining processes

Vision control systems applied to manufacturing processes have become an important research area in recent years. In this proceeding a robust and innovative artificial vision algorithm (AVA) has been developed in order to control the positioning system of a micro-machine tool mounted with a camera-LCD screen system. This study differs from previous research by using an enhanced AVA, which processes the capture image of pattern of LEDs, where the gap between illuminated LEDs is of one single LED, thus gaining in resolution. A new camera lens has been mounted on the micro-machine tool, which jointly moves with the XY platform with better resolution that that applied in previous research. The camera captures the optimized image of the tool path represented in the form of a series of lighted LEDs on a 326ppi smartphone screen. Moreover, the implementation of two new processes, such as the auto-alignment and autofocus along with a robust grid window of 5×5 lighted LEDs, let the AVA be more robust and accurate. As a result, a significant positioning error decrease is achieved for the controlling system, thus obtaining and important precision and repeatability improvement in the position system of the micro-machine tool.

Five-axis interpolation of continuous short linear trajectories for 3[PP]S-XY hybrid mechanism by dual Bezier blending

A novel five-axis real-time interpolation algorithm for 3[PP]S-XY hybrid mechanism is proposed in this paper. In the algorithm, the five-axis tool path for controlling this hybrid mechanism is separated into two sub-paths. One sub-path describes the movement of 3[PP]S parallel kinematic mechanism module, and the other one describes the movement of XY platform. A pair of cubic Bezier curves is employed to smooth the corners in those two sub-paths. Based on the homogenous Jacobian matrix of 3[PP]S mechanism, a relationship between the position errors of every driving joint in hybrid mechanism and the position deviation of the tool tip center point at the moving platform is established. This relationship is used to estimate the approximation error for the corners smoothing according to the accuracy requirement of tool tip center in interpolation. Due to the high computational efficiency of this corner smoothing method, it is integrated into the look-ahead module of computer numerical control (CNC) system to perform online tool path smoothing. By performing the speed planning based on a floating window scheme, a jerk limited S-shape speed profile can be generated efficiently. On this basis, a realtime look-ahead scheme, which is comprised of path-smoothing and feedrate scheduling, is developed to acquire a speed profile with smooth acceleration. A monotonic cubic spline is employed for synchronization between those two smoothed sub-paths in tool path interpolation. This interpolation algorithm has been integrated into our own developed CNC system to control a 3PRS-XY experimental instrument (P, R and S standing for prismatic, revolute and spherical, respectively). A club shaped trajectory is adopted to verify the smoothness and efficiency of the five-axis interpolator for hybrid mechanism control.

Design of an Optimal PID Controller by Genetic Algorithms for a Pantograph Type XY Platform

This study focused on the development of an intelligent motion control system for a nanoscale micro-platform based on the pantograph mechanism. The platform is designed to satisfy the need for achieving high accuracy and process efficiency in the manufacture of increasingly small industrial products. The target platform is mounted on a pantograph and small x-y sliders, and is driven by a traditional X-Y platform with common precision. The goal of this study is to drive the target platform to move in the region of 20mm × 20mm for the positioning, and repeatedly positioning accuracy error is less than 800 nm by a traditional X-Y platform. Due to the different PID parameters will affect platform positioning accuracy and system response for the two axes, the optimal PID parameters by the Genetic algorithms was proposed. The simulation and experimental results indicated that the proposed method is feasible for development of an intelligent motion control system for the nanoscale micro-platform positioning.

Application of Fuzzy Control in Linear Motor XY Platform

Limited by the matrix operation ability of normal control CPU (e.g. MCU, PLC and so on), the realization of fuzzy control always via the way of “calculate offline and inquire online”. Applications and practices have proved that such a realization method brings system steady-sate error, and limited the application range of fuzzy control. Based on the study of FC theory and the analysis of Mamdani fuzzy reasoning from geometrical meaning, a real-time fuzzy controller is designed and used in a Linear Motor XY Plaform control system based on Motion control card. The results show that the Real-time FC can avoid the steady-state error effectively and improve the controllability further.

Automatic Tracking and Manipulation for Cell Lysis System Development

An automatic platform for cell localization using image processing and electroosmotic flow technology was developed and used the in vivo human leukemic cells (U937) experiments. The in vivo cells were located successfully in the assigned area by aluminum electrode with lithography process. The cells were lysised with electroporation then DNA was collected in this study. First, a CCD was used to take video from microscope and then a PCI image card acquired the image data to computer. The program was designed to find cell location and trace the in vivo cell and then the cell driving mechanism is started through the voltage or time of electrode controlled with fuzzy logic method by LabVIEW package software. In addition, the XY platform is automatically controlled to keep the cell within the field of view. When the in vivo cell enters the assigned lysis area, the cell will be electroporated by the electrode. The monitoring software was developed to track and manipulate single in vivo cell to lysis successfully in this study. It can control cell move to the assigned location fatly.

Population calcium imaging of spontaneous respiratory and novel motor activity in the facial nucleus and ventral brainstem in newborn mice

The brainstem contains rhythm and pattern forming circuits, which drive cranial and spinal motor pools to produce respiratory and other motor patterns. Here we used calcium imaging combined with nerve recordings in newborn mice to reveal spontaneous population activity in the ventral brainstem and in the facial nucleus. In Fluo-8AM loaded brainstem-spinal cord preparations, respiratory activity on cervical nerves was synchronized with calcium signals at the ventrolateral brainstem surface. Individual ventrolateral neurons at the level of the parafacial respiratory group showed perfect or partial synchrony with respiratory nerve bursts. In brainstem-spinal cord preparations, cut at the level of the mid-facial nucleus, calcium signals were recorded in the dorsal, lateral and medial facial subnuclei during respiratory activity. Strong activity initiated in the dorsal subnucleus, followed by activity in lateral and medial subnuclei. Whole-cell recordings from facial motoneurons showed weak respiratory drives, and electrical field potential recordings confirmed respiratory drive to particularly the dorsal and lateral subnuclei. Putative facial premotoneurons showed respiratory-related calcium signals, and were predominantly located dorsomedial to the facial nucleus. A novel motor activity on facial, cervical and thoracic nerves was synchronized with calcium signals at the ventromedial brainstem extending from the level of the facial nucleus to the medulla–spinal cord border. Cervical dorsal root stimulation induced similar ventromedial activity. The medial facial subnucleus showed calcium signals synchronized with this novel motor activity on cervical nerves, and cervical dorsal root stimulation induced similar medial facial subnucleus activity. In conclusion, the dorsal and lateral facial subnuclei are strongly respiratory-modulated, and the brainstem contains a novel pattern forming circuit that drives the medial facial subnucleus and cervical motor pools.