• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.7 s.172
• /
• pp.94-101
• /
• 2005

This work proposes a new method for describing the hysteresis non-linearity of a piezoelectric actuator. The hysteresis behaviour of piezoelectric actuators, including the minor loop trajectory, are modeled by geometrical relationship between a reference major loop and its minor loops. This hysteresis model is transformed into inverse hysteresis model in order to output compensated voltage with regard to the given input displacement. A feedforward neural network, which is trained by a feedback PID control module, is incorporated to the inverse hysteresis model to compensate unknown dynamics of the piezoelectric system. To show the feasibility of the proposed feedforward-feedback controller, some experiments have been carried out and the tracking performance was compared to that of simple PTD controller.

• Journal of the Korean Society for Precision Engineering
• /
• v.28 no.12
• /
• pp.1379-1387
• /
• 2011

A PID-feedforward controller and Robust Internal-loop Compensator (RIC) based on reinforcement learning using random variable sequences are provided to auto-tune parameters for each controller in the high-precision position control of PMLSM (Permanent Magnet Linear Synchronous Motor). Experiments prove the well-tuned controller could be reduced up to one-fifth level of tracking errors before learning by reinforcement learning. The RIC compared to the PID-feedforward controller showed approximately twice the performance in reducing tracking error and disturbance rejection.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10a
• /
• pp.129-132
• /
• 1996

There is a tendency nowadays to produce increasingly miniaturized electronic equipment which incorporate parts that have to be precisely positioned, like lenses, heads and CCD's in scanners, printers, copiers, VCR's, optical fiber modules, etc. In contrast to the production process of precision parts, which is currently being carried out automatically, the assemblage process is still being performed by specially skilled technicians. The assemblage process comprises normally the following steps: firstly, the parts are roughly positioned and partially fixed, secondly, the parts are manually nudged towards the target position and finally glued, screwed or welded. This paper presents a system that uses six piezo Impact Drive Mechanisms for accurate micro positioning within three degrees of freedom (lateral and longitudinal translation and rotation). The system is designed to positioning a printed circuit board with an accuracy better than 3 .mu.m (for translations), 5 mrad (for rotation).

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.4
• /
• pp.152-162
• /
• 1996

The purpose of this study is the development of a lathe which can cut any pistons of oval shape with high speed, accuracy and precision by CNC (Computer Numerical Control) method. Y axis which is the position determinating mechanism with high speed response was added to the CNC lathe and the ovality and profile was cut under the control of C-Y-Z axes at same time. In the case of ovality of .phi. 0.2mm, the productivity can be improved up to 2500rpm(Y axis:83Hz) by high speed cutting than modeling method. Since a personal computer is used, it is easy to change the shape of pistion and can be applied promptly to many types of piston shppe by only changing data files.

• 제어로봇시스템학회:학술대회논문집
• /
• 1988.10a
• /
• pp.433-437
• /
• 1988

Direct measurement of the relative position between the end effector of robot and moving objects reduces difficulties caused by the joint encoder reading and transformation. For those purpose, the on-line sensing method using PSD sensor was developed in this paper. The sensor was calibrated on the precision table. Then, the relative position of a moving objects on the conveyor was measured while the robot was tracking the one.

• Proceedings of the KIPE Conference
• /
• 2004.07a
• /
• pp.219-223
• /
• 2004

Since rotor position information is necessary to drive the SRM, absolute-encoder, resolver and incremental encoder is used to detect a rotor position. But, it is not desirable to use a high price encoder and microprocessor under the condition of the simple driving system when precision control is not demanded. In this paper, only using the reflective type two photo-sensors replaces the conventional opto-interrupter and slotted-disk, which not only remove a slotted-disk section but drive three-phase 6/4 pole SRM bidirectionally, Therefore, control circuit can compose common analog device with low price.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.612-615
• /
• 2002

This paper begin a new approach in the water-gate control using radio communication. The dissertation is on the controllable device development of water-gate in the remote distance from water-gate trough the transceiver by radio communication. The proposed water-gate control device is simpe in structure, an suitable for implementation of water-gate control in the remote distance. The remote controller water-gate device inspected the up and down motion of water-gate through the LCD displayer, so that it was very safety driving about the surroundings imformation, over loading and position of water-gate, and so on.

• Journal of the Korean Society for Precision Engineering
• /
• v.12 no.7
• /
• pp.138-147
• /
• 1995

The conventional PWM method, which was used in controlling the on-off valve, such as high-speed solenoid valve, was modulating the width of the pulse applied to the valve, by selecting arbitrary sampling time and modulating the duty-ratio in proportion to the error. However, in this method, a selection of long sampling time was inevitable and it was unable to get a high accuracy and a quick response. This study is for designing an appropriate controller for high-speed solenoid valve by proposing an improved duty-ratio modulation method using the Saw-toothed Carrier Wave which enables a short sampling time selection, high accuracy of control, and a quick response. Test which was carried out in the laboratory shows that transient and steady state response could be improved by PID controller.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1944-1947
• /
• 2005

In this paper, the control of a prosthetic arm using the flex sensor signal is described. The flex sensors are attached to the biceps and triceps brchii muscle. The signals are passed a differential amplifier and noise filter. And then the signals are converted to digital data by PCI 6036E ADC. From the data, position and velocity of arm joint are obtained. Also motion of the forearm - flexion and extension, the pronation and supination are abstracted from the data by proposed algorithm. A two D.O.F arm with RC servo-motor is designed for experiment. The arm length is 200 mm, weight is 4.5 N. The rotation angle of elbow joint is $120^{\circ}$. Also the rotation angle of the wrist is $180^{\circ}$. Through the experiment, we verified the possibility of the prosthetic arm control using the flex sensor signal. We will try to improve the control accuracy of the prosthetic arm continuously.

• Journal of the Korean Society for Precision Engineering
• /
• v.4 no.4
• /
• pp.25-35
• /
• 1987

This paper deals with the design of the digital controller for DC servo motor, and it is implemented for the cartesian coordinate 4 axes manipulator. A design method of the controller is adopted an algorithm using the digital position locked loop(DPLL) method and the linear PID control for the smooth motion. To simplify the hardware configuration of control system, 8279 keyboard/display controller, Z-80 CTC counter and 8255 PPI are used. Therefore the design method to control each motor as real-time is presented. To show effectiveness of the design, the PWM circuit and frequency/voltage converter are applied for the velocity control of robot system. When the proposed controller is applied to the 4-axes manipulator, it reveals that the error probabilities of X, Y and Z axis as 0.033%, 0.023% and 0.028% respectively.