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This paper describes the successful development of a middle-range six-degrees-of-freedom stage, using the features of a flexible structure. The system includes two parts: a middle-range positioning X— Y stage and a four-degrees-of-freedom stage. The flexible structure of the four-degrees-of-freedom stage is built from two kinds of flexible bodies: circular hinges and a new two-degrees-of-freedom flexible body. The four-degrees-of-freedom stage was designed to compensate movement errors including linear displacement, pitch, and roll errors. The linear displacement reaches 20 mm along the X-axis, 20 mm along the Y-axis, and 5 μm along the Z-axis. The rotation angle around the X-axis (θ x), Y-axis (θ y), and Z-axis (θ z) were all 10 arcsec. A novel six-degrees-of-freedom measuring system was also designed. Precision feedback control is demonstrated in a series of experiments performed using the proposed measurement system.

At present, the accuracy of precision manufacture is most affected by straightness errors, so the measurement and compensation of these errors are very important. In the current paper, three measurement systems for straightness are presented; they are characterized by simple set-up, online measuring, low cost, and sub-micrometre accuracy achieving 0.2 μm. Experimental results show that these three measurement systems can be applied to implement a compensation system which comprises one among them, an Elmo controller, and a dSPACE controller, and accomplish static compensation and dynamic compensation in the dual linear-axis stage. The accuracies of the static and dynamic compensation achieve ± 1 μm and ± 2.5 μm, respectively.

In this study, a simple and high-resolution four-degrees-of-freedom (4-DOF) motion error measuring system based on DVD pickup has been proposed. It can simultaneously measure the horizontal straightness error and three angular errors of a single-axis linear moving platform. The horizontal straightness error is measured based on the focus technique of DVD pickup and the inverse algorithm is used to solve pitch, yaw, and roll angular errors through the kinematic analysis. The grating is mounted on the moving axis of a single-axis linear moving platform and reflects incident laser beam into several diffractive rays. Photodiode IC (PDIC) of DVD pickup is set up for detecting the focus error signal (FES) of zero-order diffraction ray from grating and quadrant detectors are set up for detecting the position of ±1st-order diffraction rays from grating. The 4-DOF motion error measuring system detected the three angular errors with a related accuracy of about ±1 arc sec for a measuring range of ±100 arc sec, and detected horizontal straightness with a related accuracy of about ±2 μm for a measuring range of ±150 μm.

In this paper a method is developed for straightness measurement of a linear guide by using a straightness self-compensating stage with an optical straightness measuring system, an eddy current sensor, and a cross-roller type compensation stage. Both the compensation stage and the optical straightness system were set up on a scanning stage to measure the straightness error of the scanning stage. The measured straightness error was fed back to the control system to compensate directly in real time. Thus, straightness of a linear guide without the added straightness error of the scanning stage could be measured. The Hewlett Packard laser straightness calibration system was used to verify the real-time compensated results. Straightness error of the scanning stage was compensated from the worst straightness error of 20 μm/150 mm to 0.9 μm/150 mm. The eddy current sensor measured straightness of the linear guide and the measured result matched the result obtained by the coordinate measuring machine.

In this paper, it presents a useful dual-axial five-degrees-of-freedom measuring system with five degrees of freedom (DoFs) for the simultaneous measurement of five-DoF motion errors of a nano-stage. The system integrates a miniature fibre-coupled laser interferometer with specially designed optical paths and quadrant detectors, capable of measuring five-DoF motion errors. It presents a new precision five-DoF measuring system which has been developed and implemented for the simultaneous measurement of five-DoF motion errors (two linear positions, as well as pitch, roll, and yaw) of a nano-stage. In this paper, the five-DoF laser interferometer was produced by designing the optical path from the one-DoF laser interferometer. The system employs two three-DoF interferometers to detect two position errors and three angular errors of the nano-stage. The experimental set-ups and measuring procedure and a systematic calculated method for the error verification are presented as well. The resolution of measuring the angular errors component is about 0.06″.

In this study, a high-resolution three-degrees-of-freedom (3-DOF) motion error measuring system based on interference is described. It can simultaneously measure the linear displacement and two angular errors of a single-axis linear moving platform. The displacement is measured using a polarization interference technique and the two angular errors are also measured based on the geometry optical theorem. The verification results show that the resolution is about 20 nm. The 3-DOF measurement system detected displacements relative to a measurement mirror move with an accuracy of about ±8 μm for a measuring range of ± 50 mm, and detected the angular errors with a related accuracy of about ± 2 arc sec for a measuring range of ± 100 arc sec.

The current paper concentrates on the design and manufacturing process of a stack-type nanometre positioning stage with high accuracy and multiple degrees of freedom for a heavy-loading machine. The stack-type stage described in this paper comprises a flexible structure as the primary component and can be easily adjusted from single-axis movement to a five-degrees-of-freedom motion to cope with different needs. Piezoelectric actuators are known for their unique features, such as quick response, high resolution, electrical mechanical coupling efficiency, and low heat generation. Therefore, six piezoelectric actuators are provided to trigger the five-degrees-of-freedom motion for the positioning stage. The stage sensor is provided with five capacitive sensors inside the five-degrees-of-freedom stage to measure the stage displacement. As indicated by the experimental results, the linear displacement reaches 52. 76 μm along the x axis, 51. 79 μm along the y axis, and 12. 08 μm along the z axis. The rotation displacement around the x axis is θ x = 184 μrad and the rotation displacement around the y axis is θ y = 277 μrad. The heavy-loading test indicates that the stage is capable of taking a load of 12 kgs.

The accuracy of machine tools restricts the dimensional accuracy of parts processed thereon. It is, therefore, necessary to monitor the errors of machine tools constantly. Normally, it takes a long set-up time before one can observe the machine tool and monitor its errors. The cost of such delays is inevitably high. As for CNC, the conventional measurement system is capable of measuring one-dimensional signals, as a laser interferometer does, and two-dimensional signals, as a grid encoder does. Three-dimensional measurement techniques, however, are far from being well developed and are not yet well known. This paper proposes a triangulation method incorporating three built-in linear-scale ball bars that requires less set-up time and lower costs than the laser ball bar system, and is capable of acquiring three-dimensional signals with greater accuracy with the extension bars, so that large volumes can be checked.

THis paper presents a useful measuring method for rapidly verifying geometric errors using a double-readheads planar encoder system. The system is capable of comparing the displacement measurements between two parallel lines simultaneously when the machine axes are moved. With the calculated model and the various specified test paths, the proposed measuring method provides rapid performance, simplicity of set-up, low cost and pre-process verification of computer numerical control (CNC) machine tools. Complete set-ups and procedures for geometric error verification are clearly presented. Also, the proposed system tested the dynamic performance of the CNC machine tools. It is an integrated system that can complete both dynamic performance and the geometric verification of CNC machine tools.

There are two kinds of alignment systems, marked and unmarked. The glass substrate for touch panels is categorized as an unmarked work piece. Vision based glass substrate alignment (GSA) relies on the edge of the glass. Traditional GSA systems compensate first for angular and then for linear error. This reduces alignment accuracy and increases alignment time and edge detection usually takes longer than 10 ms. This study proposes an effortless edge detection method. This method is very simple and can significantly reduce the time taken to detect the edge to about 6 ms using a 1.3 megapixel image. In this study, a floating center idea is used to control the glass substrate on a high precision coplanar XXY alignment stage. According to the method, users can set the rotation center anywhere as long as it is on the working ( xy) plane. Tolerance prognosis is also considered in this study to help the operator decide if the substrate is usable or should be rejected. The experimental results show alignment repeatability of the x, y, and θ axes to be 1 μm, 1 μm, and 5 arcsec, respectively.