• Journal of the Korean Society of Industry Convergence
• /
• v.20 no.4
• /
• pp.299-305
• /
• 2017

This study proposes a new technique to design and control of robot hand gripper for assembling and disassembling of a machine parts. The motion equation describing dynamics of the manipulators and object together with geometric constraint is formulated by Lagrange-Euler's equation. And the problems of controlling both the grasping force and the rotation angle of the grasped object under the constraints are analyzed. The effect of geometric constraints and a method of computer simulation for overall system is verified. Finally, it is illustrated that even in case of there exists a sensory feedback from sensing data of the rotational angle of the object to command inputs control of joint and this feedback connection from sensing data to control grasping of machinery parts.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.18 no.2
• /
• pp.181-188
• /
• 2015

This paper present, the result of the guidance and control law for a course correction munitions(CCM) with 2sets of canards positioned in the rotating nose section. The nonlinear simulation model of the CCM was developed based on 7DOF equation of motion. The ability of correcting position was verified by open-loop control input with nonlinear model. The guidance and control command was constructed by reference trajectory which can be obtained with no control. Finally, the performance of the guidance and control law was evaluated through Monte-carlo simulation. The CEP(Circular Error Probability) was obtained by considering the errors in muzzle velocity, aerodynamic coefficient, wind, elevation and azimuth angle and density.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.46 no.8
• /
• pp.631-638
• /
• 2018

In this paper, we propose a method to improve the performance by guidance technique and applying it to the precision guided ammunition. The proposed method is a technique designed to reduce the target error of ammunition by reducing the projectile error without analyzing the motion characteristics of the shot. This technique is applied to the moving average filter technique which is widely used as signal processing technique to reduce the fluctuation of the output of the inboard mounting inertial sensor caused by the rotation and the coning motion of the ammunition. In order to compare the performance of the applied technique including the simple 3D guided control technique and the proposed improvement technique. It is confirmed that the application of this technique improves the accuracy of impact of the cannon - launched ammunition with severe environmental conditions and irregular motion characteristics unlike the missile.

• Journal of Biosystems Engineering
• /
• v.40 no.1
• /
• pp.35-46
• /
• 2015

Purpose: To present a flexible and accurate autonomous solution for creating any desired row spacing value between the hydroponic gullies in multilayer growing units, and evaluate the capabilities and performance of the relevant automated system through the use of virtual prototyping technique. Methods: To build the virtual prototype of the system, CAD models of its different parts, including an autonomous vehicle and the mechanical mechanisms embedded in the multilayer growing unit, were developed and imported into the RecurDyn simulation software. In order to implement the automated row spacing operation, three spacing modes with different loading cycles and working steps were defined, and the operation of the system was simulated to obtain the target row spacing values specified for each of these modes. Results: Motion profiles related to the horizontal displacement of: 1) the lower and upper sliding bars installed in the cultivation layers, and 2) the hydroponic gullies, during the simulation of the system operation, were generated and analyzed. No deviation from the specified target spacing values was observed at the end of simulations for all spacing modes. Conclusions: The results of the motion analysis obtained by simulating the system operation confirm the effectiveness of the control scheme proposed for automated row spacing of gullies. It was also found that proper sequencing of the loading cycles and the precision of the working strokes of the upper bars are the critical factors for establishing a certain row spacing value. Based on the simulation results, precise control of the back and forth motions of the upper bars is highly necessary for sound operation of the real system.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.05a
• /
• pp.132-135
• /
• 2002

In the present study, an electro-mechanical KAFO (knee-ankle-foot orthosis) which satisfies both the stability in stance and the knee flexion in swing was developed and evacuated in eight polio patients. A knee joint control algorithm suitable for polio patients who are lack of the stability in pre-swing was also developed and various control systems and circuits were also designed. In addition, knee flexion angles and knee moments were measured and analyzed for polio patients who used the developed KAFO with the three-dimensional motion analysis system. Energy consumption was also evaluated for the developed KAFO by measuring the movement of the COG (center of gravity) during gait. From the present study, the designed foot switch system successfully determined the gait cycle of polio patients and controlled knee joint of the KAFO, resulting in the passive knee flexion or foot clearance during swing phase. From the three-dimensional gait analysis for polio patients, it was found that the controlled-knee gait with the developed electro-mechanical KAFO showed the knee flexion of 40$^{\circ}$∼45$^{\circ}$ at an appropriate time during swing. Vertical movements of COG in controlled-knee gait (gait with the developed electro-mechanical KAFO) were significantly smaller than those in looked knee gait(gait with the locked knee Joint). and correspondingly controlled-knee gait reduced approximately 40% less energy consumption during horizontal walking gait. More efficient gait patterns could be obtained when various rehabilitation training and therapeutic programs as well as the developed electro-mechanical KAFO were applied for polio patients.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.756-759
• /
• 2004

We present a piezoelectric actuator using stiffness control and stroke amplification mechanism in order to make large lateral displacement. In this work, we suggest stiffness control approach that generates lateral displacement by increasing the vertical stiffness and reducing the lateral stiffness using additional structure. In addition, an additional structure of a serpentine spring amplifies the lateral displacement like leverage structure. The suggested lateral PZT actuator (bellows actuator) consists of serpentine spring and PZT/electrode layer which is located at the edge of the serpentine spring. The edge of the serpentine spring prevents the vertical motion of PZT layer, while the other edge of the serpentine spring makes stroke amplification like leverage structure. We have determined dimensions of the bellows actuator using ANSYS simulation. Length, width and thickness of PZT layer are 135$\mu$m, 20$\mu$m and 0.4$\mu$m, respectively. Dimensions of the silicon serpentine spring are thickness of 25$\mu$m, length of 300$\mu$m, and width of 5$\mu$m. The bellows actuator has been fabricated by SOI wafer with 25$\mu$m-top silicon and 1$\mu$m-buried oxide layer. The bellows actuator shows the maximum 3.93$\pm$0.2$\mu$m lateral displacement at 16V with 1Hz sinusoidal voltage input. In the frequency response test, the fabricated bellows actuator showed consistent displacement from 1Hz to 1kHz at 10V. From experimental study, we found the bellows actuator using thin film PZT and silicon serpentine spring generated mainly laterally displacement not vertical displacement at 16V, and serpentine spring played role of stroke amplification.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1883-1886
• /
• 2005

In this paper, a decoupled dual servo (DDS) stage for ultra-precision scanning system with large working range is introduced. In general, dual servo systems consist of a fine stage for short range and a coarse stage for long range. The proposed DDS also consists of a $XY\theta$ fine stage for handling and carrying workpieces and one axis coarse stage. Its coarse stage consists of air bearing guide system and a coreless linear motor with force ripple. The fine has four voice coil motors(VCM) as its actuator. According to a VCM's nature, there are no mechanical connections between coils and magnetic circuits. Moreover, VCM doesn't have force ripples due to imperfections of commutation components of linear motor systems - currents and flux densities. However, due to the VCM's mechanical constraints the working range of the fine is about $25mm^2$. To break that hurdle, the coarse stage with linear motors is used to move the fine about 500mm. Because of the above reasons, the proposed DDS can achieve higher precision scanning than other stages with only one servo. With MATLAB's Sequential Quadratic Programming (SQP), the VCMs are optimally designed for the highest force under conditions and constraints such as thermal dissipations due to its coil, its size, and so on. And for their movements without any frictions, guide systems of the DDS are composed of air bearings. To get precisely their positions, a linear scale with 5nm resolution are used for the coarse stage's motion and three plane mirror laser interferometers with 5nm for the fine's $XY\theta$ motions. With them, on scanning the two stages have same trajectories. The control algorithm is named Parallel method. The embodied ultra-precision scanning system has sub 100nm following error and in-positioning stability.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1824-1827
• /
• 2005

For application to micro fluid control systems such as ${\mu}TAS$ (Micro Total Analysis Systems) and DDS (Drug Delivery Systems), it is very significant to handle precise and minute flow rates with low pressure pulsation. In this study, a novel valveless piezoelectric pump using peristaltic motion with three disk type PZT actuators is presented. The newly devised pump with an effective size of $70mm{\times}60mm{\times}55mm$ has three actuator layers connected in series from inlet to outlet. The PZT actuator has a maximum displacement of 240 ${\mu}m$ and a maximum force of 1.6 N. When the driving voltage for PZT actuators is sequentially applied with a certain phase shift, the pumping is performed by peristaltic motion of liquid volume. The working fluid is shut off without the driving voltage. Three methods for sequential driving are proposed and experimentally investigated. First and second methods utilize an intermittent sinusoidal waveform with phase shift of $90{\circ}\;and\;120^{\circ}$, respectively. Third method uses a rectangular waveform with phase shift of $90^{\circ}$. A controller with multi-phase shifter is designed and fabricated. Then, frequency and voltage-flow rate characteristics and load pressure-flow rate characteristics are experimentally investigated to verify the validity of the developed pump.

• Journal of Biomedical Engineering Research
• /
• v.25 no.6
• /
• pp.511-517
• /
• 2004

The existing rehabilitation systems were developed to exercise specific joints only. Therefore rehabilitating the various joints of human, various kinds of devices are need. To overcome these defects, this paper proposed the CMRS, an integrated system that performs various rehabilitation exercises. The characteristics of motion and the positions between human body and the system were investigated with the kinematics analysis of upper and lower limb of human body. We presented a proper mechanism to develop a rehabilitation device on the base of the study and studied the relative positions between head part and human joints. Through the simulations, the possibility of rehabilitation system was verified. And the base frame was also developed for convenient and stable position control. Finally, the CMRS was developed as an 8 degree of freedom mechanism. It is expected that the CMRS will be applied to the rehabilitations of various joints.

• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.1275-1278
• /
• 1997

Cutting process has been automated by progress of CNC and CAD/CAM, but polishing process has been depended on only experiential knowledge of expert. To automate the polishing pricess polishing robot with 2 degrees of freedom which is attached to a machining center with 3 degrees of freedom has been developed. this automatic polishing robot is able to keep the polishing tool normal on the curved surface of die to improve a performance of polishing. Polishing task for a curved surface die demands repetitive operation and high precision, but conventional control algorithm can not cope with the problem of disturbance such as a change of load. In this research, we develop robust controller using real time sliding mode algorithm. To obtain gain parameters of sliding model control input, the signal compression method is used to identify polishing robot system. To obtain an effect of 5 degrees of freedom motion, 5 axes NC data for polishing are divided into data of two types for 3 axis machining center and 2 axis polishing are divided into data of two types for 3 axis machining center and 2 axis polishing robot. To find an efficient polishing condition to obtain high quality, various experiments are carried out.