• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2009.04a
• /
• pp.214-215
• /
• 2009

The friction is inevitable and unpredictable phenomena, so most mechanical systems are designed to low friction effect by using bearings and lubricants. However, the slip-stick actuator applies the friction force to its movement. The slip-stick mechanism is applied the piezoelectric actuator to overcome short displacement. Fast response of piezoelectric actuator is also good characteristic for the slip-stick mechanism. However, the piezoelectric actuator with slip-stick mechanism isn't common, because its cost and driving voltage are too high. In this paper, a voice-coil actuator with slip-stick mechanism is introduced. The cost and the driving voltage of a voice-coil actuator are much less than the piezoelectric actuator. And a dynamic vibration amplifier is proposed to adjust the dynamic performance of the actuator. By the results of numerical analysis, the feasibility of a dynamic vibration amplifier is verified.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2009.06a
• /
• pp.279-280
• /
• 2009

• Journal of the Korean Society for Precision Engineering
• /
• v.18 no.4
• /
• pp.64-71
• /
• 2001

In general, precise linear actuators using piezoelectric element are driven by friction force. Exact understanding of friction plays an important role in analysis and control of a motor. In this research, we designed a precise linear actuator using piezoelectric elements and observed its dynamic characteristics. By varying phase angle difference and amplitudes of the sinusoidal waves that are driving inputs, we can know that it is possible to control moving direction and distance of the slider. As preload is increased, its moving distance is decreased. And also, we have modeled a precise linear actuator using stick slip friction models such as classical, Karnopp. and reset integrator. Finally, by comparing the results of simulation and experiment, it was verified that the model is well designed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2008.11a
• /
• pp.230-236
• /
• 2008

In this paper, a model-based stick-slip compensation for the micro-positioning is proposed using an enhanced stick-slip model based on statistical rough surface contact model. The smart structure is comprised with PZT (lead (Pb) zirconia (Zr) Titanate (Ti)) based stack actuator incorporating with the PID (Proportional-Integral-Derivative) control algorithm, mechanical displacement amplifier and positioning devices. For the stick-slip compensation, the elastic-plastic static friction model is used considering the elastic-plastic asperity contact in the rough surfaces statistically. Mathematical model of system for the positioning apparatus was derived from the dynamic behaviors of structural parts. PID feedback control algorithms with the developed stick-slip model as well as feedforward friction compensator are formulated for achieving the accurate positioning performance. Experimental results are provided to show the performances of friction control using the developed positioning apparatus.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.18 no.11
• /
• pp.1134-1142
• /
• 2008

In this paper, a model-based stick-slip compensation for the micro-positioning is proposed using an enhanced stick-slip model based on statistical rough surface contact model. The smart structure is comprised with PZT(lead (Pb) zirconia(Zr) Titanate(Ti)) based stack actuator incorporating with the PID(proportional-integral-derivative) control algorithm, mechanical displacement amplifier and positioning devices. For the stick-slip compensation, the elastic-plastic static friction model is used considering the elastic-plastic asperity contact in the rough surfaces statistically. Mathematical model of system for the positioning apparatus was derived from the dynamic behaviors of structural parts. PID feedback control algorithms with the developed stick-slip model as well as feedforward friction compensator are formulated for achieving the accurate positioning performance. Experimental results are provided to show the performances of friction control using the developed positioning apparatus.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.37 no.4
• /
• pp.399-405
• /
• 2009

The focal plane image stabilization for a satellite camera is one of the an effective method which can increase the satellite camera's image quality by removing the motion disturbance of a focal plane. The objectives of this article are to introduce the concept of the focal plane image stabilization and determine the best driving conditions of the actuator for the response and thrust. Under various driving condition the experiments have been performed to investigate the response and thrust characteristics of the piezoelectric driven stick-slip actuator of the focal plane image stabilizing device. From experiments, the best driving frequency and duty ratio for the magnesium slider are 70 kHz and 27%, respectively.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.751-756
• /
• 2008

This paper presents the fluid characteristics of the spool actuator used for construction vehicles. A spool actuator is used for directional control of pressurized fluid and has a roll to lock the fluid flow. It is important to design the spool actuator optimally because this actuator is actuated in the sleeve by sliding motion and has some critical design parameters such as stick-slip, leakage and shock pressure. The parameters like stick-slip and leakage can be solved by precision manufacturing but the shock pressure which is taken place when the fluid direction is changed needs the parameter analysis procedure throughly. In this study, mathematical modeling and 2 & 3 phase flow dynamics analysis of the spool actuator were achieved. Using suggested model, all possible operating conditions were analyzed.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.20 no.5
• /
• pp.1419-1425
• /
• 1996

In this work, a precies actuator which is capable of high positioning accuracy is developed. For estimation the dynamic behavior of the actuator, system modeling is performed by employing a stick-slip frection law. Dynamic characteristics over various types of driving input signals and vibraiton loci of the driving tip are examined by experiments. Phase differences between the input signals are applied, and the dynamic behavior of slider is investigated. From the simulation and experimental results, it is observed that the dynamic behaviors from the simulation results agree fairly well to those of the experimental results. Thisindicates that the model developed in this work is applicable to other precision mechanisms in which a friction farce is as improtant factor for actuation.

• Journal of Advanced Navigation Technology
• /
• v.13 no.5
• /
• pp.756-762
• /
• 2009

As nonlinear friction, stick-slip friction in hydraulic actuators are a problem for accuracy and repeatability. Therefore friction compensation has been approached through various control algorithms. A Adaptive discrete time sliding mode tracking controller has been applied in order to compensate the nonlinear friction characteristics in a hydraulic Actuator. Based on the diophantine equation, a new discrete time sliding function is defined and utilized for the control law which includes a friction and modeling error. Robustness is increased by using both a projection algorithm and a sliding function-based nonlinear feedforward. From the results of simulation and experiment good tracking performance is achieved.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.7 no.2
• /
• pp.60-65
• /
• 2008

The high-technology industries including a semi-conductor and an information communication need an ultra-precision technology from the technological points of view. Nano technology based on an ultra-precision technology is being studied to overcome the delicate technology that may occur in the semi-conductor fields. Then, the transferring equipment with high resolution and long displacement becomes an important technology. The goal of this study is to analyze the displacement magnification mechanism driven by piezoelectric actuator which has high resolution and fast response characteristics using flexure hinge with the merits of soft displacement, negligible back-lash and stick-slip, and no-lubrication. The analyses to reduce the magnification losses occurred during the magnification process are performed using ANSYS software based on FEM. The five design variables such as arm thickness, thickness of hinge, radius of hinge, length of input side at the 1st lever and magnification ratio of 1st lever are optimized to induce the maximum magnification ratio using Taguchi method.