• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.60.2-60
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• 2002

$\textbullet$ Contents 1: Introduction to nonlinear crane model $\textbullet$ Contents 2: Passivity of the crane model $\textbullet$ Contents 3: PD-Control based on the passivity $\textbullet$ Contents 4: Global regulation of the system without the velocity measurement $\textbullet$ Contents 5: Simulation studies for the performance test

• The Journal of Korea Robotics Society
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• v.19 no.1
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• pp.8-15
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• 2024

This paper proposes a linear model predictive control of 6-DOF remotely operated underwater vehicles using nonlinear robust internal-loop compensator (NRIC). First, we design a integrator embedded linear model prediction controller for a linear nominal model, and then let the real model follow the values calculated through forward dynamics. This work is carried out through an NRIC and in this process, modeling errors and external disturbance are compensated. This concept is similar to disturbance observer-based control, but it has the difference that H_∞ optimality is guaranteed. Finally, tracking results at trajectory containing the velocity discontinuity point and the position tracking performance in the disturbance environment is confirmed through the comparative study with a traditional inverse dynamics PD controller.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.12
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• pp.1306-1316
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• 1990

A controller using a multilayer neural network is proposed to the dynamic control of a PUMA 560 robot arm. This controller is developed based on an error back-propagation (BP) neural network. Since the neural network can model an arbitrary nonlinear mapping, it is used as a commanded feedforward torque generator. A Proportional Derivative (PD) feedback controller is used in parallel with the feedforward neural network to train the system. The neural network was trained by the current state of the manipulator as well as the PD feedback error torque. No a priori knowledge on system dynamics is needed and this information is rather implicitly stored in the interconnection weights of the neural network. In another experiment, the neural network was trained with the current, past and future positions only without any use of velocity sensors. Form this thim window of position values, BP network implicitly filters out the velocity and acceleration components for each joint. Computer simulation demonstrates such powerful characteristics of the neurocontroller as adaptation to changing environments, robustness to sensor noise, and continuous performance improvement with self-learning.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.8
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• pp.627-636
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• 2021

This paper deals with a study for the guidance control of reusable launch vehicle. For this purpose, modeling of the equation of motion of a reusable launch vehicle with 6 degrees of freedom was performed. With this model, an optimal re-entry path was created and a path-following guidance control simulation was performed to follow the optimal re-entry path. For the design of the path-following guidance controller, the attitude controller applying a time-delay technique that is resistant to modeling uncertainty, disturbance and failure. And the nonlinear path-following guidance law were used. Guidance control simulation using a classical PD controller was performed and compared with the guidance control simulation of a reusable launch vehicle applying a time delay technique.

• International Journal of Automotive Technology
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• v.5 no.2
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• pp.77-88
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• 2004

Narrow commuter vehicles can address many congestion, parking and pollution issues associated with urban transportation. In making narrow vehicles safe, comfortable and acceptable to the public, active tilt control systems are likely to playa crucial role. This paper focuses on the development of an active direct tilt control system for a narrow vehicle that utilizes an actuator in the vehicle suspension. A simple PD controller can stabilize the tilt dynamics of the vehicle to any desired tilt angle. However, the challenges in the tilt control system design arise in determining the desired lean angle in real-time and in minimizing tilt actuator torque requirements. Minimizing torque requirements requires the tilting and turning of the vehicle to be synchronized as closely as possible. This paper explores two different control design approaches to meet these challenges. A Receding Horizon Controller (RHC) is first developed so as to systematically incorporate preview on road curvature and synchronize tilting with driver initiated turning. Second, a nonlinear control system that utilizes feedback linearization is developed and found to be effective in reducing torque. A close analysis of the complex feedback linearization controller provides insight into which terms are important for reducing actuator effort. This is used to reduce controller complexity and obtain a simple nonlinear controller that provides good performance.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.2
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• pp.165-171
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• 2016

A prosthetic knee for above-knee (AK) amputee is categorized into passive and active type. The passive prosthetic knee is generally made by elastic material. Although AK amputee can easily walk by using passive prosthetic leg, knee joint motions are not similar to ordinary persons. The active prosthetic leg can control the knee angle owing to the actuator and microprocessor. However, the active type is not cost-effective and the stability may be lost due to the malfunction of sensors. In order to resolve these disadvantages of passive and active type, a semi-active prosthetic knee which can control the knee angle is proposed in this work. The proposed semi-active one requires a less input energy but provides active type performance. In order to achieve this goal, in this work, a semi-active prosthetic knee using magneto-rheological (MR) damper for AK amputees is designed. The MR damper can support the weight of body by using less energy than actuator of active prosthetic. It can control knee angle by inducing the magnetic field at the time of stance phase. This salient characteristic is evaluated and presented in this work.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.4
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• pp.40-46
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• 2006

It is required to develop a highly reliable attitude & orbit control system of satellite that is less expensive as the technology of satellite design & integration is recently matured dramatically. To accomodate this kind of needs, the two axis attitude control method for wheel-based momentum-biased satellite system whose momentum bias vector points to a certain direction(sun direction), is developed using simple but reliable sensors and actuator: three axis magnetometer and coarse sun sensor are used as sensors, and magnetic torque bars are used as actuator. Classical PD type controller design methodologies are applied on a satellite system for the two axis control with the proper assumptions. Nonlinear simulation results are included to demonstrate the long term stability and the performance of closed-loop system design results.

• Proceedings of the KIEE Conference
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• 2000.11d
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• pp.650-652
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• 2000

Although Fuzzy Logic Controller(FLC) adopted three terms as input gives better performance. FLC is in general composed of two-term control because of the difficulty in the construction of fuzzy rule base. In this paper, a three-term FLC which is similar to PID control but acts as a nonlinear controller is proposed. To reduce the complexity of the rule base design and increase efficiency, a simplified fuzzy PID control is induced from a hybrid velocity/position type PID algorithm by sharing a common rule base for both fuzzy Pi and fuzzy PD parts. It is simple in structure, easy in implementation, and fast in calculation. The phase plane technique is applied to obtain the rule base for fuzzy two-term control and them. The resultant rule base is Macvicar-Whelan type. The frequency response information is used in tuning of membership functions. Also a tuning strategy for the scaling factors is Proposed based on the relationship between PID gain and them. Simulation results show better performance and the effectiveness of the proposed method.

• Journal of Industrial Technology
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• v.20 no.B
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• pp.155-162
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• 2000

Although Fuzzy Logic Controller(FLC) adopted three terms as input gives better performance, FLC is in general composed of two-term control because of the difficulty in the construction of fuzzy rule base. In this paper, a three-term FLC which is similar to PID control but acts as a nonlinear controller is proposed. To reduce the complexity of the rule base design and to increase efficiency. a simplified fuzzy PID control is induced from a hybrid velocity/position type PID algorithm by sharing a common rule base for both fuzzy PI and fuzzy PD parts. It is simple in structure, easy in implementation, and fast in calculation. The phase plane technique is applied to obtain the rule base for fuzzy two-term control and the resultant rule base is Macvicar-Whelan type. And the membership function is a Gaussian function. The frequency response information is used in tuning of the membership functions. Also a tuning strategy for the scaling factors is proposed based on the relationship between PID gain and the scaling factors. Simulation results show better performance and the effectiveness of the proposed method.

• Journal of Advanced Navigation Technology
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• v.20 no.3
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• pp.175-181
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• 2016

This paper introduces a heave compensation system for offshore crane when it gets unexpected disturbances and external force. The dynamic model consists of crane assumed to be the rigid body, hydraulic driven winch, elastic rope and payload. To keep the payload from moving up and down, PD control algorithm is applied. By using the control, the oscillating amplitude of the payload is reduced. Also by using the estimated values involved with time-delay, the relative motion of payload in heave direction is dramatically shortened. This paper shows using the control algorithm with estimated value having time-delay 0.1 second is enough to heave compensation system.