• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.653-660
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• 2000

The automatization by industrial robot of today is merely rely on to the simple position repeating works, but requirements of research and development to the force control which would adapt positively to various restriction or contacting works to environment. In this paper, a learning control algorithm using, neural networks is proposed for the position and force control by a direct-drive robot. The proposed controller is the feedback controller to which the learning function of neural network is added on to and has a character of improving controller's efficiency by learning. The effectiveness of the proposed algorithm is demonstrated by the experiment on the hybrid position and force control of a parallelogram link robot with a force sensor.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.11B no.2
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• pp.28-33
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• 2001

The subject of this study is to improve the position performance of the linear motion for hybrid type Linear Pulse Motor (HLPM). Generally, there are two applicable methods to ensure precise position control ; a good processing method. This paper is suggested an electrical 125 microstep driving method so as to achieves the excellent control performance, besides the small mechanical manufacture of teeth pitch. The compensation method of digital PI control is apply to step response of stable position control, step error, vibration suppression and the approach to high stability, and the Ziegler-Nichols tuning method is applied to the proper design of control parameter. The proposed control method has been verified by simulation results of the suitable gain and phase margin of bode plot, and from experiment result of step response.

• Journal of the Korean Society of Industry Convergence
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• v.22 no.4
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• pp.435-445
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• 2019

Ball screw drives are widely used in industry, and many studies have been devoted on precise, fast and robust control of ball screw drives. In this study, a novel position control algorithm for ball screw drives is proposed, which consist of a PD controller, a friction feedforward and a disturbance observer. The dynamics and the position error of such controller are analyzed to establish an error model, which can be used to predict the resulting position error of the given desired trajectory. Using the proposed error model, the desired trajectory can be modified so that the predicted position error can be compensated in a feedforward manner. The proposed algorithm does not require the model of the system for the error prediction, and thus can be easily applied to conventional control systems. The performance of the system is verified through simulations and experiments.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.3
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• pp.216-222
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• 2017

The rotor position of a PM synchronous motor is commonly estimated from the mathematical model for the sensorless control without rotor position sensors. For the magnet flux-based rotor position estimator in the stationary reference frame, the magnet flux estimator for estimating rotor position and speed includes the integrator. The integrator in the magnet flux estimator may accumulate the offset of the current sensors and the voltage drift. This continuous accumulation of the offset may cause the drift and overflow in the integrator, such that the estimated rotor position and speed may fail to track the real rotor position and speed. In this paper, the magnet flux estimator without integrator is proposed to avoid overflow in the integrator. The proposed rotor position and speed estimator based on magnet flux estimator are verified through simulation and experiment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.12
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• pp.2078-2090
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• 2001

This paper deals with a precise position synchronous control by a cooperative control method of two axes rotating systems. First, the system's dynamics including motor drives described by a motor circuit equation and Newton's kinetic formulation about rotating system. Next, based on conventional PID(Proportional, Integral, Derivative) control law, current and speed controller are designed very simply to follow up reference speed correctly under some disturbances. Also, position synchronous controller designed to minimize position errors according to integration of speed errors between two motors. Then, the proposed control enables the distributed drives by a software control algorithm to behave in a way as if they are mechanically hard coupled in axes. Further, the stabilities and robustness or the proposed system are investigated. Finally, the proposed system presented here is shown to be more precise position synchronous motion than conventional systems through some simulations and experiments.

• Journal of Drive and Control
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• v.16 no.3
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• pp.23-32
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• 2019

This study proposed a fault tolerant control algorithm for electro-hydraulic brake systems where permanent magnet synchronous motor (PMSM) drive is adopted to boost the braking pressure. To cope with motor position sensor faults in the PMSM drive, a braking pressure controller based on an open-loop speed control method for the PMSM was proposed. The magnitude of the current vector was determined from the target braking pressure, and motor rotational speed was derived from the pressure control error to build up the braking pressure. The position offset of the pump piston resulting from a leak in the hydraulic system is also compensated for using the open-loop speed control by moving the piston backward until it is blocked at the end of stroke position. The performance and stability of the proposed controller were experimentally verified. According to the results, the control algorithm can be utilized as an effective means of degraded control for electro-hydraulic brake systems in the case that a motor position sensor fault occurs.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.10
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• pp.969-976
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• 2008

A position control problem is studied for UEV(Unmanned Expedition Vehicles), which is to follow pre-determined paths via fixed way-points. Hybrid control systems are used for position control of UEV depending on the operating condition. Speed control consists of three controllers: PID control, adaptive PI control, and neural network. Heading control consists of two controllers, PID and adaptive PID control. The controllers are selected based on the changes of road conditions. We suggest an adaptive PI control algorithm for speed control and an transition management algorithm among the controllers. The algorithm adapts the road conditions and variation of vehicle dynamical characteristics and selects a suitable controller.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.593-596
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• 2008

The reed switch position transmitter (RSPT) is used as a position indicator for the control rod in commercial nuclear power plants made by ABB-CE. But this position indicator has some problems when directly adopting it to the integral reactor. The Control Element Drive Mechanism (CEDM) for the integral reactor is designed to raise and lower the control rod in steps of 2mm in order to satisfy the design features of the integral reactor which are the soluble boron free operation and the use of a nuclear heating for the reactor start-up. Therefore the resolution of the position indicator for the integral reactor should be achieved to sense the position of the control rod more precisely than that of the RSPT of the ABB-CE. This paper adopts seismic resistance reed switches to the position indicator in order to reduce the damages or impacts during the handling of the position indicator and earthquake.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1786-1790
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• 2004

The main objective of this paper is to analyze the performance of various force control algorithms in improving and adjusting the compliance of industrial robots in contact with their environment. Some of fundamental force control algorithms such as sensorless control, impedance control and hybrid position/force control are theoretically analyzed and simulated for various situations of an environment, and then a series of experiments using them were performed. In this paper, a control scheme to use position control in implementing the impedance control was investigated in order to nullify the effect of joint friction. The new reference trajectory is generated using contact force feedback and original desired trajectory. And an inner position control loop is designed to provide accurate position tracking for the new reference trajectory and good disturbance rejection. Experiments to insert a peg in a hole (so-called the peg-in-a-hole task) were performed with HILS (hardware-in-theloop simulation) system based on the results of the analyses and simulations on the characteristics of each control algorithm. The experiments showed that various force control methods improved the performance of robots in close contact with the environment by adjusting their compliance with respect to an arbitrary set of coordinates.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.9
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• pp.1468-1474
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• 2001

In this paper, a new fuzzy-logic anti-swing control scheme is proposed for a three-dimensional overhead crane. The proposed control consists of a position servo control and a fuzzy-logic control. The position servo control is used to control the trolley position and rope length, and the fuzzy-logic control is used to suppress load swing. The proposed control guarantees not only prompt suppression of load swing but also accurate control of trolley position and rope length for the simultaneous travel, traverse, and hoisting motions of the crane. The effectiveness of the proposed control is shown by experiments with a prototype three-dimensional overhead crane.