• Proceedings of the KIEE Conference
• /
• 2006.07d
• /
• pp.2155-2156
• /
• 2006

The purpose of this work is to investigate the fundamental properties of the gradual muscle force potentiation for the prediction of muscle force and body movement from the stimulation input with musculo-skeletal model. We investigated the dependence of force potentiation on both the pulse-amplitude and the pulse-duration. The experimental result showed that the force increment ratio during electrical stimulation decreased with pulse-amplitude. The force increment ratio decreased with short pulse-duration and was maintained to be constant with pulse-duration longer than $500{\mu}s$. A new model of the muscle potentiation based on these results is desired in the future.

• Tribology and Lubricants
• /
• v.11 no.1
• /
• pp.20-26
• /
• 1995

Most magnetic bearings are based on the attractive force between the magnets and ferrous materials. One of the disadvantages of such attractive type magnetic bearings is the instability so that an active control device is necessary to operate bearing successfully. In this study a repulsive type magnetic bearing is analyzed which uses eddy current as a force source. The load capacities are analyzed for the various gap sizes, the rotor velocities and the frequencies of current supplied to electromagnet. Analytic Results show that as the gap size decreases, the levitation and drag forces increase, while the number of poles increasqs, the drag force decreases in the higher linear velocity region. Experimental results show that as the gap size decreases the levitation and the drag force increase, and as the velocity of rotor increases, the drag is larger than the levitation force up to certain velocity. But after that, the levitation is larger than the drag force. As the frequency of the current increases the levitation and drag decreases while the thickness of rotor gets thicker the forces decrease because of increase in eddy current loss.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.25 no.6
• /
• pp.426-431
• /
• 2015

In this work, a new type of MR damper with additional flow path in piston is proposed and damping force characteristics are numerically evaluated. Flow-mode type MR damper is considered and mathematical model is established based on Bingham rheological model of MR fluid to obtain accurate prediction of damping force characteristics. Damping force of the proposed MR damper are calculated with respect to piston velocity and input current. In addition, investigation on damping force characteristics is carried out according to number of additional flow path and excellence of the proposed MR damper is demonstrated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.06a
• /
• pp.1058-1064
• /
• 2000

The analysis of dynamic behaviour of rotor system for the rolling piston type rotary compressor considering hydrodynamic force between motor rotor and stator is presented. In addition to considering other dynamic, loads such as large unbalance forces, gas force and bearing force, we consider the hydrodynamic force induced by the compressed fluid flow through the air gap between motor rotor and stator, and improve the analysis of vibration in rotary compressor. The Childs' method which based on Bulk-now and Hirs' turbulent lubrication model is used to calculate the rotordynamic coefficients due to hydrodynamic force of annular clearance in motor air gap.

• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.422-422
• /
• 2000

Parallel manipulators have been used to a variety of applications, including the motion simulators and mechanism for precise machining. A Stewart-Gough type parallel manipulator is composed of six linear joints which have wider contact areas than revolute ones, so linear joints are more affected by frictional force. First, the reference trajectories are computed from the model of the parallel manipulator assuming that it is subject to only the gravitational force and no friction exists. In the actual operation where friction exists, the control inputs, which correspond to the friction forces, are obtained by forcing the actual joint variables to follow these trojectories by proper control. It is shown that control performance can be improved when the friction compensation based on this information is added to the controller for position control of the moving plate of a parallel manipulator.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.18 no.4
• /
• pp.369-374
• /
• 2009

In micro/nano-scale contacts in MEMS and NEMS, capillary and van der Waals forces generated around contacting micro-asperities significantly influence the performance of concerning device as they are closely related to adhesion and stiction of interacting surfaces. In this regard, it is of prime importance to accurately estimate the magnitude of surface forces so that an optimal solution for reducing friction and adhesion of micro/nano-surfaces may be obtained We introduced an effective method to calculate these surface forces based on topography information obtained from an atomic force microscope. This method was used to calculate surface forces generated in the contact interface formed between diamond-like carbon coating and $Si_3N_4$ ball. This method is shown to effectively demonstrate the influence of capillary force in the contact area, especially in humid atmosphere.

• Journal of Drive and Control
• /
• v.14 no.3
• /
• pp.25-31
• /
• 2017

This study presents a methodology for simulating a unified approach that controls interaction force between tool and objective by using a synthesis method of robot interacting control law for stabilizing the transient process of motion. Root locus is used to analyze stabilization of motion deviation characteristics. Based on responses of motion deviation, contact force is derived to satisfy exponential stability and we generate control input with respect to motion trajectories and interaction force. Moreover, simulation is applied to experimental application of a Cartesian robot driven by two stepper motors, and the noise of feedback signals is considered as presence of system inaccuracies, and the unified approach of interaction force control is examined precisely.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 2002.10a
• /
• pp.141-146
• /
• 2002

Real-time monitoring and control of the cutting force is essential for unmanned cutting process. Although the cutting force can be measured directly using tool dynamometers, their implementation is not feasible in industry due to high cost. Alternative approach is the cutting force estimation based on spindle drive models, but it requires the knowledge of their characteristics with the spindle speed variation. This paper investigates the power-factor and frictional characteristics of three-phase induction motors and determines its characteristics below and above the base speed, respectively. In order to realize the proposed cutting force monitoring system, a stand-alone DSP board was utilized. Its monitoring and control performance is evaluated in a CNC lathe.

• International Journal of High-Rise Buildings
• /
• v.3 no.2
• /
• pp.121-145
• /
• 2014

The story shear force distributions of most seismic design codes generally reflect the influences of higher vibration modes based on the elastic deformations of structures. However, as the seismic design allows for the plastic behavior of a structure, the story shear force distribution shall be effective after it is yielded due to earthquake excitation. Hence this study conducted numerical analyses on the story shear force distributions of most seismic design codes to find out the characteristics of how a structure is damaged between stories. Analysis results show that the more forces are distributed onto high stories, the lower its concentration is and the more energy is absorbed. From the results, this study proposes the optimum story shear force distribution and its calculation formula that make the damages uniformly distributed onto whole stories. Consequently, the story damage distribution from the optimum calculation formula was considerably more stable than existing seismic design codes.

• Journal of the Korean Society for Precision Engineering
• /
• v.31 no.3
• /
• pp.243-251
• /
• 2014

In inference fit assembly process of the industrial robot, it basically needs the force data. One of the typical methods to get the force data is attaching torque sensors on the robot arm joint or end effector. This is effective way to reduce time delay and to improve preciseness of force control, but this method has several problems. To solve that problem, this paper suggests method which measures assembly force without torque sensor by using the sliding perturbation observer(SPO) and assembly process based on SPO to assemble successfully in inference assembly