• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.4
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• pp.276-283
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• 2017

This paper presents position control of multicopter using nonlinear dynamic model inversion in singular perturbation. Multicopter dynamics are developed and separated into the fast time-scale variables, related with the inner-loop design, and the slow time-scale variables, related with the outer-loop design. The final design is evaluated in 6-DOF simulation. The results show accurate position tracking performance.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.299-304
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• 1988

This paper describes the application of the variable structure control(VSC) concept for the position control of electro-hydraulic servomtor system. The basic philosopy of VSC is that the structure of the feedback control is altered as the state crosses discontinuity surfaces in the state surface with the result that certain desirable properties are achieved. The switching of the control function yields total(or selective) invariance to system parameter variations and disturbances, and closed loop eigen value placement in time-varing and uncertain systems.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.4
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• pp.9-21
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• 2003

This paper describes the practical implementation of a semiactive hydropneumatic suspension system to provide the high off-road performance of military tracked vehicles. Real gas behavior of a spring system, frictional forces of joints, and the dynamics of a continuously variable damper are considered. The control system is consisted of two control loops, an outer loop calculates a target spool position which can deliver the required damping force and an inner loop tracks the required spool position. Dynamic tests of the one axis model show that the semiactive suspension system considerably reduces the acceleration as well as velocity and displacement of the sprung mass than the passive one.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1269-1274
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• 2004

This paper presents a new quantisation algorithm which has the closed-loop form and guarantees the boundness of accumulative error. This algorithm is particularly useful for mobile robot navigation that is usually implemented on embedded systems. If wheel commands of the mobile robot are given by velocity or positional increment at every control instant and quantised due to finite word length of controller's CPU, the quantisation error gets accumulated to causes large position error. Such an error accumulative characteristic is fatal for non wheeled mobile robots or autonomous vehicles with non-holonomic constraint. To solve this problem, we propose a non-error accumulative quantisation algorithm with closed-loop form. We also show it can be extend to a generalized form corresponding to the n-th order accumulation. The boundness of the accumulative quantisation error is investigated by a series of computer simulation. The proposed method is particularly effective to precise navigation control the autonomous mobile robots.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1008-1013
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• 2005

In this paper, position tracking control of an autonomous helicopter is presented. Velocity is controlled by using an optimal state controller LQR. A position control loop is added to form a PD controller. To minimize a position tracking error, neural network is introduced. The reference compensation technique as a neural network control structure is used, and a position tracking error of an autonomous helicopter is compensated by neural network installed in the remotely located ground station. Considering time delays between an autonomous helicopter and the ground station, simulation studies have been conducted. Simulation results show that the LQR with neural network compensation performs better than that of the LQR itself.

• International Journal of Control, Automation, and Systems
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• v.6 no.3
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• pp.386-393
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• 2008

A position control method for interpolating aspherical grinding and polishing tool path was reviewed and experimented in a nano precision machine. The position-base algorithm was reformed from the time-base algorithm, proposed in the previous study. The characteristics of the algorithm were in the velocity control loop with position feedback. The aspherical surface was divided by an interval at which each velocity and acceleration were calculated. The theoretical velocity was corrected by position error during processing. In the experiment, a machine was constructed and nano-scale linear encoders were installed at each axis. Relation between process parameters and the variation of position error was monitored and discussed. The best result from optimized parameters showed that the accuracy was 150nm and improved from the previous report.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.10a
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• pp.209-214
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• 1992

This paper presents a one cycle R&D project regarding the large inertia platform servo control system. The steps followed the rather orthodox procedure. A serial double rate-loop was closed with a position loop, and acceleration velocity anticipatory compensations were designed in the forward path. Some appropriate compensation devices were utilized for the signal processing as well as for the better control quality. Simulations and experimental tests were repeated, and satisfactory performances were observed. However, frequency domain uncertainties inherent to the large structures still remain as an expertise supported subject.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.469-470
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• 2008

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.332-337
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• 1988

A digital series-feedback compensator algorithm for tracking time-varying signal is presented. The series-feedback compensator is composed of one closed loop pole / zero cancellation compensator and one desired-input generator. This algorithm is applied to nonlinear hydraulic position control system. The hydraulic servo system is modelled as a second order linear model and cancellation compensator is modelled from it. The desired input generator is inserted to reduce modelling error. Digital computer simulation output using this control method is present and the usefulness of this control algorithm for nonlinear hydraulic system is verified.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.460-463
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• 1995

The present paper studies a robot manipulator's contact tasks on the uncertain flexible objects. The flexible object's distributed parameter model is approximated into a lumped "position state-varying" model. By using the well-known nonlinear feedback compensation, the robot's control space is decomposed into the position control subspace and the object's torque control subspace. The optimal state feedback is designed for the position loop, and the robot's contact force is controlled through controlling the resultant torque on the object using model-reference simple adaptive control. Experiments of a PUMA robot interacting with an aluminum plate show the effectiveness of this control approach. approach.