Two-axis Position Research Articles

Cascade Control for Two-Axis Position Mechatronic Systems

The current paper proposes an extension for two controller design procedures for a two-axis positioning mechatronic system, followed by a comparison between them. As such, the first method consists in formulating an optimization problem in terms of linear matrix inequalities (LMIs) in order to impose the location of the closed-loop poles, considering an uncertain model of such a system. The uncertain model is treated using various forms of linear differential inclusions (LDIs), namely, polytopic LDI (PLDI) and diagonal norm-bound LDI (DNLDI). Additionally, the problem regarding the command signal constraints is characterized in terms of LMIs. The imposed structure of the controller is a cascade one, with a PI controller for the position loop and a P controller for the velocity loop, having an additional feedforward term. On the other hand, the second method consists in designing a cascade controller with an inner P controller, as in the previous method, the outer controller being a fractional-order IλIDλD (FO–ID) controller. In terms of degrees of freedom, both methods present four degrees of freedom for each axis. The presented controller design procedures will be applied for a numerical example of such a positioning system, and a comparison of the obtained performance metrics will be performed.

An Approach of Electronic Subdividing Method for Measuring Straightness and Displacement of a Precision Linear Stage Simultaneously

Optical encoders are commonly used in modern positioning systems. The accuracy and resolution of the optical encoders are always restricted by generated sinusoidal signals and the assembly technique. In this study, an electronic signal subdividing system is developed. This system is based on FPGA in combination with A/D and D/A converting circuits. Subdividing algorithm improves the segmenting signal amplitude method. Furthermore, we also construct a laser encoder for measuring straightness error and displacement of a linear stage simultaneously. The laser encoder consisting of the stainless steel bar and the sensor are developed for two-axis (X- and Z-axis) position measurement. The two dimensional sinusoidal array on the stainless steel bar are machined by ultrasonic elliptical vibration cutting system. The stainless steel bar has a three dimensional micro-structured surface, which is a superposition of periodic sinusoidal waves in the X- and Z-directions with spatial wavelengths of 350 µm and amplitudes of 0.5 µm. The laser-based two-axis position sensor is used to detect local slope profiles of the grid surface, and the displacement and straightness error could be extracted from the X- and Z-axis sensing signal. The sensing signal is processed by FPGA subdividing system. In addition, the proposed subdividing method is verified by the performances and effects of measuring results.

Research on the Stability of the Position Servo Motor Control System Based on DSP

in this paper, a very low cost two-axis position servo system is developed. This system is controlled by DSP. We study the stability of the position servo control system. We use the PI control algorithm in our application. We achieved twice switching frequency by using PWM signals to share the switching dissipation ePWM module of the DSP. A numerical consideration is given. The simulation results demonstrate the stability of the proposed method.

2A2-P23 レーザを固定座標系として用いる3軸姿勢・2軸位置センサの開発(非接触センシング)

This paper proposes a three-axis attitude and two-axis position sensor using a laser light as fixed coordinate. It consists of a beamsplitter, plane of projection and camera. Its structure is simple and compact. We show its structure and principle of measurement. The width, length and height of the developed sensor are 47.5 mm, 70 mm and 32 mm respectively. We have experimentally verified that the sensor can measure three-axis attitude and two-axis position.

Servo and tracking algorithm for a probe storage system

Very fast, precise and robust servo algorithm and tracking algorithm for a probe storage system are proposed, which use only probes without any additional high-resolution position sensors. Servo algorithm uses the values read by servo probes as the coordinate of every data bit with one-to-one correspondence so that it provides high accuracy, short seek-time, and robustness. Also the concept of virtual subsection of data field is introduced to reduce the number of the servo probes. Tracking algorithm can detect two-axis position errors used for off-track control and synchronization independently and continuously. By vibrating the scanner and by multiplying two decomposition signals, position errors are modulated and demodulated from probe reading signal. Servo+track code is designed to reduce total number of additional probes for servo and tracking and to have stable noise characteristics.

Precision Measurement of Two-Axis Positions and Tilt Motions Using a Surface Encoder

A prototype surface encoder consisting of a sinusoidal angle grid and a two-dimensional slope sensor is developed for two-axis position measurement. The angle grid has a three dimensional micro-structured surface, which is a superposition of periodic sinusoidal waves in the X- and Y-directions with spatial wavelengths of 150 μn and amplitudes of 100 nm over an area of up to 150 mm in diameter. The laser-based slope sensor is used to read local slope profiles of the grid surface. The X- and Y-positions together with tilt motions about the X-, Y- and Z-axes can be detected with resolutions of 0.1 μm and 1 arc-second through scanning a multi-spot laser beam across the grid surface at a constant speed.

H∞제어기법에 의한 커플링구조의 위치동기제어에 관한 연구

In this study, a synchronous controller algorithm being applicable to two-axis position synchronzation is developed. Based on coupling structure, the synchronous control system is composed of speed and synchronous controllers. The speed controller is designed to follow a speed reference. In addition, the synchronous controller is designed from the viewpoint of accurate synchronization and robust stability in H synthesis. Finally, the effectiveness of the presented controller is demonstrated through extensive experiments.Āࠀ會Āࠀꢤﾖ⨀䠚馟ĀĀ會ĀĀ¥ﾖ⨀馟ĀĀ會ĀĀ墥ﾖ⨀耛馟ĀĀ會ĀĀ낥ﾖ⨀僡亙ĀĀ會ĀĀࢦﾖ⨀亙ĀĀ會ĀĀ悦ﾖ⨀郢亙Ā᐀會Ā᐀뢦ﾖ⨀ᢘ墵Ā저會Ā저Ⴇﾖ⨀나墵Ā㰀會Ā㰀梧ﾖ⨀備墵ĀḀ會ĀḀ삧ﾖ⨀끿쾯ĀḀ會ĀḀᢨﾖ⨀ꁯ᪢ԀĀ᐀會Ā᐀炨ﾖ⨀㡰᪢܀܀좨ﾖ⨀

Wireless transmission of power and information through one high-frequency resonant AC link inverter for robot manipulator applications

A contactless decentralized power supply is proposed with communication capability through only one transformer. A prototype of a wireless transmission system of power and information (WTPI system) was built, and the two-axis position controls of servo motors were achieved by transferring the power and signal through one rotatable high-frequency transformer. The proposed concept can be applied for robotics and numerical control (NC) machines.