Earticle

For motor controller designers, building a simulation environment is not a difficult process. After verifying the controller by simulation, it is common to select 20kHz for the current control loop, 1kHz for the speed loop, and 100Hz for the position loop when implementing the actual HW embedded system. This is because maximized cycles (20kHz) for each control loop are unnecessary in control theory and are a waste of cost and HW resources. However, in a simulation environment, each loop will often have the same control cycle (20kHz maximum). This is because we think it is unnecessary to reflect this part in the simulation. In this paper, it is shown that the difference in the sampling time of each control loop makes a big difference in the simulation result, and as a solution, it is proposed to apply LPF to the position loop output stage. In the process, the reasons for the differences were analyzed, and the effect of LPF, the reason for application, and the feasibility of implementation were proved by actual software coding.

Controller modeling is essential for the design. It allows various control techniques to be simulated in advance, and various interpretations can be performed. If this is not the case, we need to reverse engineering in the real system developed by others. In this paper, controller modeling was reversely designed using the frequency test results of the target system. First, the characteristic equation of the target equipment was based on and a block diagram was assumed. Thereafter, controller variables were estimated using the frequency test results for each of the four control loops. In addition, time response simulations were performed using the estimated controller modeling. This method is thought to be of great help to reverse engineering in situations where there is completed equipment but no controller modeling.

A robust controller is proposed for regulating effectively the pressure of control cylinder of swash plate type variable displacement axial piston pump. In order to design a precise and robust pressure control system, a mathematical model for swash plate control system is identified by the signal compression method. Based on the identified mathematical model, an $H_{\infty}$ robust swash plate controller is designed which is robust to the variation of the load pressure. The precise and robust swash plate control characteristics are verified by experiments.

This paper deals with dynamic modeling and controller design of a future Korean lunar module planned to be launched 2020's in Korea. For dynamic modeling of the lunar module, we first assume the lunar module as a rigid body. And we derive equations of motion for the lunar module by considering allocation of main thrusters and reaction thrusters. With the equation of motion, we design the controller based on the quaternion. A Pulse Width Pulse Frequency modulator(PWPFM) is selected for generating on/off signal. Finally, we construct a 2-phase descent mode including initial guidance mode, terminal guidance mode. The MATLAB simulation is performed for evaluating the descent ability and final landing velocity. The dynamic modeling and descent simulation of the lunar module in this paper could be applied for developing the future work of the Korean lunar exploration program.

Some of Spacecraft's structures are flexible so that a certain expected disturbance can easily excite a low frequency vibration on these structures, having very low natural damping. Such vibration will degrade the performance of the system, which should to be kept in a specific shape or attitude against the undesired vibration. In this paper, LQG/LTR controller is developed using an additional dynamic model to increase the performance of the frequency responses at low frequency area. This study presents that the LQG/LTR design was an effective controller for the flexible structure.

Recent developments of robotics allocated many of industrial and medical activities. So that most of industries turned to use surgical robots in their production line or in their surgery. Being precise, spent less time-consuming, present uniform quality with less cost and reducing waste and energy are some advantages of using robots in industry. This paper has two important objectives: a) study on modeling and controlling of 4 degrees of freedom (DOF) based on Simscape software and b) design FPGA-based controller for this type of surgical robot manipulator. Simscape provides an environment for modeling and simulating physical systems. Simscape modeling can be designed to control and test system-level performance. Conventional PID controller is a stable linear type model-free controller that reduces the delay time in highly nonlinear system. In this research, linear controller need real time mobility operation, and one of the most important devices which can be used to solve this challenge is Field Programmable Gate Array (FPGA). FPGA can be used to design a controller in a single chip Integrated Circuit (IC). To design PID type FPGA-based controller two types algorithm are needed: derivative algorithm and integral algorithm. In HDL based derivative algorithm the minimum input arrival time before clock is 16.466 ns and the maximum frequency is 60.73 MHz, but in the best design action, the maximum frequency to design this single chip algorithm should be 63.629 MHz. In HDL integral algorithm the minimum input arrival time before clock is 15.599 ns and the maximum frequency is 64.1 MHz, but in the best design action, the maximum frequency to design this single chip algorithm should be 178.190 MHz.

In this article, a dynamic model of a six degrees of freedom (6 DOF) Eight-Rotor MAV (micro aerial vehicles) is derived on the basis of the Newton-Euler formalism. The derivation comprises determining equations of the motion of the Eight-Rotor MAV in three dimensions and approximating the actuation forces through the modelling of aerodynamic coefficients and electric motor dynamics. For Eight-Rotor MAV is inherently unstable as they are highly sensitive to external perturb, here provides an adaptive double neural network controller for the motion control of the Eight-Rotor MAV autonomous flight. This controller is developed in three parts around each of the variables. The experimental results show that the proposed adaptive double neural network controller outperforms the conventional PID controller due to its fast adaptive qualities in the presence of sensor measurement noise and the parameters variations of Eight-Rotor MAV.

This paper presents a mathematical approach of the controlling of Unmanned Aerial Vehicle (UAV) translational and rotational movement dynamics by using classical regulation, pole-placement & tracking (RST) controller with model reference adaptive control (MRAC). Identification of a black box is done by using the Least Square Estimation (LSE) method while MIT rule is used as a control algorithm in conjunction with the RST controller with MRAC. The desired result of 6-degrees of freedom (DOF) via Multiple Input and Multiple Output (MIMO) model comprises the equation of motions which utilizes UAV to stabilize the nonlinear, translational and rotational movement implements the adaptive approach via initial conditions at the start of vertical takeoff. The numerical approach simplifies the control equations of the tri-rotor and stabilizes towards linearity. The resulted control strategy is affected over nonlinear simulation for each control dynamic and gives more stability with less power requirements. Hence the adaptive algorithm is ensuring the controlling and stability of the system.

Current-fed isolated bidirectional DC-DC converters (CF-IBDCs) play an important role in battery energy storage systems. However, the closed-loop dynamics is rather slow with conventional proportional-integral controllers because a precise mathematic model remains absent for optimization. In this paper, a simple precise mathematical model is presented to describe the large and small-signal behaviors of the CF-IBDC. The full-order continuous model can accurately capture the dynamic behaviors and cover all operation conditions. The small-signal model is derived, and the DC filter inductors and clamp capacitors are found to be the natural causes of instability. Based on this finding, special controllers are proposed to optimize the dynamic response of the full closed-loop control system. The dynamic response time of the CF-IBDC is greatly reduced with the proposed controller. The correctness of the presented model and the dynamic response of the optimized closed-loop control system are verified by simulations.

The controlled smart hanger is an indispensable component in the automatic system for garment inspection. Fuzzy logic is chosen for the smart hanger manipulator since it can describe the human behavior remarkably well. In this paper, the dynamic model of the manipulator governing the contact force with garment fabric is first developed. An adaptive fuzzy logic PID control scheme is successfully formulated for the contact force control. Simulation results indicate that the fuzzy PID controller can yield a faster response without overshoot and a smaller error performance as compared to the traditional method based on PID. The stability of the fuzzy PID controller is also demonstrated by computer simulations.

An Intelligent active roll angle controller design algorithm is discussed. The detailed mathematical formulation and analysis are discussed, and then modeling and design method for active roll angle controller are presented. This paper proposes a design method based upon intelligent robust controller design algorithm to control actively roll angle for improving cornering performance problems. The intelligent robust controller is designed for steady speed driving vehicle system model with representation of steering angle and yaw angular velocity parameters for cornering stability. And the detailed formulation and analysis for the objective vehicle system are investigated.

An Intelligent active roll angle controller design algorithm is discussed. The detailed mathematical formulation and analysis are discussed, and then modeling and design method for active roll angle controller are presented. This paper proposes a design method based upon intelligent robust controller design algorithm to control actively roll angle for improving cornering performance problems. The intelligent robust controller is designed for steady speed driving vehicle system model with representation of steering angle and yaw angular velocity parameters for cornering stability. And the detailed formulation and analysis for the objective vehicle system are investigated.

There are many intermediate web guides in cold rolling mills process such as CRM (cold rolling mill), CGL (continuous galvanizing line), EGL (electrical galvanizing line) and so on. The main functions of the web guides are to adjust the center line of the web (strip) to the center line of the steel process. So they are called CPC (center position control). Rapid process speed cause large deviation between the center position of the strip and the process line. Too much deviation is not desirable. So the difference between the center position of the strip and the process line should be compensated. In general, the center position control of the web is obtained by the hydraulic driver and electrical controller. In this paper, we propose modelling and several controller designs for web-guide systems. We model the web and guide by using geometrical relations of the guide ignored the mass and stiffness of the web. To control the systems, we propose PID controllers with their gains tuned by the Ziegler-Nichols method, the H$\_$$\infty$/ controller model-matching method, and the coefficient diagram method (CDM). CDM is modified for high order systems. The results are verified by computer simulations.

This paper focuses on the modeling and intelligent control of the new Eight-Rotor MAV, which is used to solve the problem of the low coefficient proportion between lift and gravity for the Quadrotor MAV. The Eight-Rotor MAV is a nonlinear plant, so that it is difficult to obtain stable control, due to uncertainties. The purpose of this paper is to propose a robust, stable attitude control strategy for the Eight-Rotor MAV, to accommodate system uncertainties, variations, and external disturbances. First, an interval type-II fuzzy neural network is employed to approximate the nonlinearity function and uncertainty functions in the dynamic model of the Eight-Rotor MAV. Then, the parameters of the interval type-II fuzzy neural network and gain of sliding mode control can be tuned on-line by adaptive laws based on the Lyapunov synthesis approach, and the Lyapunov stability theorem has been used to testify the asymptotic stability of the closed-loop system. The validity of the proposed control method has been verified in the Eight-Rotor MAV through real-time experiments. The experimental results show that the performance of the interval type-II fuzzy neural network based adaptive sliding mode controller could guarantee the Eight-Rotor MAV control system good performances under uncertainties, variations, and external disturbances. This controller is significantly improved, compared with the conventional adaptive sliding mode controller, and the type-I fuzzy neural network based sliding mode controller.

A Dynamic Voltage Restorer (DVR) model is proposed to eliminate the short-term voltage disturbances that occur in the grid-connected mode, the switching between grid-connected mode and the stand-alone mode of a Microgrid. The proposed DVR structure is based on a conventional cascaded H-bridge multilevel inverter (MLI) topology; a novel composite control strategy is presented, which could ensure the compensation ability of voltage sag by the DVR. Moreover, the compensation to specified order of harmonic is added to implement effects that zero-steady error compensation to harmonic voltage in specified order of the presented control strategy; utilizing wind turbines-batteries units as DC energy storage components in the Microgrid, the operation cost of the DVR is reduced. When the Microgrid operates under stand-alone mode, the DVR can operate on microsource mode, which could ease the power supply from the main grid (distribution network) and consequently be favorable for energy saving and emission reduction. Simulation results validate the robustness and effective of the proposed DVR system.

This paper discusses an entire procedure for a robust controller design and its implementation of an AMB (active magnetic bearing) spindle, which is part II of the papers presenting details of system modeling and robust control of an AMB spindle. Since there are various uncertainties in an AMB system and reliability is the most important factor for applications, robust control naturally gains attentions in this field. However, tight evaluations of various uncertainties based on experimental data and appropriate performance weightings for an AMB spindle are still ongoing research topics. In addition, there are few publications on experimental justification of a designed robust controller. In this paper, uncertainties for the AMB spindle are classified and described based on the measurement and identification results of part I, and an appropriate performance weighting scheme for the AMB spindle is developed. Then, a robust control is designed through the mixed ${\mu}$ synthesis based on the validated accurate nominal model of part I, and the robust controller is reduced considering its closed loop performance. The reduced robust controller is implemented and confirmed with measurements of closed-loop responses. The AMB spindle is operated up to 57,600 rpm and performance of the designed controller is compared with a benchmark PID controller through experiments. Experiments show that the robust controller offers higher stiffness and more efficient control of rigid modes than the benchmark PID controller.

This paper describes the development of a clustering based fuzzy controller of an electromagnetic suspension vehicle using gain scheduling method and Kalman filter for a simplified single magnet system. Electromagnetic suspension vehicle systems are highly nonlinear and essentially unstable systems For achieving the levitation control of the DC electromagnetic suspension system, we considered a fuzzy system modeling method based on clustering algorithm which a set of input/output data is collected from the well defined Linear Quadratic Gaussian(LQG) controller. Simulation results show that the proposed clustering based fuzzy controller methodology robustly yields uniform performance with adequate gap response over the mass variation range.

Recently, the Electro-Hydrostatic Actuator(EHA) has been developed as a result of research on energy saving. EHA is usually composed of a direct driven pump from an electric motor and is available to control cylinder displacement or velocity with high efficiency. In addition, it has the advantage of compactness, minimum leakage and availability of decentralized control. In this study, an EHA system was designed to decrease the path tracking error and manufactured for test. The linearization method provided in AMESim software was used to derive the model of EHA system. The derived model was applied to design the PI-D controller to effectively overcome the disturbance. The effectiveness of this controller was verified by further testing.

Crabbing motion is the pure sway motion of a ship without surge velocity. Thus, it can be applied to a berthing operation. Crabbing motion is induced by a peculiar operation method called the push-pull mode. The push-pull mode is induced by using a combination of the main propeller and side thruster. Two propellers generating the same amounts of thrust and rotating in opposite directions produce some yawing moment on a vessel but do not induce longitudinal motion. With the additional operation of side thrusters, the push-pull mode is used to induce a large amount of lateral force. In this paper, three-degree-of-freedom equations of motion such as for the surge, sway, and yaw are constructed for the crabbing motion. Based on these equations of motion, a feedback linearization control method is applied to auto-berthing control for a twin-screw ship with side thrusters. The controller can deal with the nonlinearity of a system, which is present in the berthing maneuver of a twin screw ship. A simulation of the auto-berthing of a ship is performed to validate the performance of the designed controller.