• 제어로봇시스템학회:학술대회논문집
• /
• 2000.10a
• /
• pp.190-190
• /
• 2000

This paper presents a multirate state feedback control (MRSFC) method for systems sensitive to disturbance and noise based on the multirate estimator design using the current estimator. MRSFC updates the controller output slower than the measurement sampling frequency of system output by a lifting factor R=T$\sub$c//T$\sub$s/. The closed-loop MRSFC system is less sensitive to disturbance and noise due to filtering effect than the conventional single-rate control system. The multirate estimator gain is obtained from solving a conventional pole placement problem such that MRSFC has the same spectrum of eigenvalues in the s-plane as the single-rate control. We applied the proposed multirate state feedback controller to a galvanometer servo system. Simulation and experimental results show that settling and tracking performances are improved compared with a conventional single-rate pole placement control (PPC).

• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.2
• /
• pp.46-52
• /
• 2014

This paper presents a multiple gain controlled digital phase and frequency detector with a fast lock-time. Lock-time of the digital PLL can be significantly reduced by applying proposed adaptive gain control technique. A loop gain of the proposed digital PLL is controlled by three conditions that are very large phase difference between reference and feedback signal, small phase difference and before lock-state, and after lock-state. The simulation result shows that lock-time of the proposed multiple gain controlled digital PLL is 100 times faster than that of the conventional structure with unit gain mode.

• International conference on construction engineering and project management
• /
• 2020.12a
• /
• pp.510-519
• /
• 2020

Within an intelligent automated cyber-physical system, the realization of the autonomous mechanism for data collection, data integration, and data analysis plays a critical role in the design, development, operation, and maintenance of such a system. This construct is particularly vital for fault-tolerant route-finding systems that rely on the imprecise GPS location of the vehicles to properly operate, timely plan, and continuously produce informative feedback to the user. More essentially, the integration of digital twins with cyber-physical route-finding systems has been overlooked in intelligent transportation services with the capacity to construct the network routes solely from the locations of the operating vehicles. To address this limitation, the present study proposes a conceptual architecture that employs digital twin to autonomously maintain, update, and manage intelligent transportation systems. This virtual management simulation can improve the accuracy of time-of-arrival prediction based on auto-generated routes on which the vehicle's real-time location is mapped. To that end, first, an intelligent transportation system was developed based on two primary mechanisms: 1) an automated route finding process in which predictive data-driven models (i.e., regularized least-squares regression) can elicit the geometry and direction of the routes of the transportation network from the cloud of geotagged data points of the operating vehicles and 2) an intelligent mapping process capable of accurately locating the vehicles on the map whereby their arrival times to any point on the route can be estimated. Afterward, the digital representations of the physical entities (i.e., vehicles and routes) were simulated based on the auto-generated routes and the vehicles' locations in near-real-time. Finally, the feasibility and usability of the presented conceptual framework were evaluated through the comparison between the primary characteristics of the physical entities with their digital representations. The proposed architecture can be used by the vehicle-tracking applications dependent on geotagged data for digital mapping and location tracking of vehicles under a systematic comparison and simulation cyber-physical system.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.16 no.1
• /
• pp.41-52
• /
• 1992

An algorithm of transforming continuous-time state feedback gains into equivalent discrete-time feedback gains or vice versa is proposed using bilinear transformation. The proposed method is evaluated experimentally by an application control of a mobile crane system which is implemented by 16bits micro computer with A/D and D/A converters. It has been shown from the experimental result that the transformed feedback gains are virtually identical to the optimal discrete gain over range of significant sampling time. Since the transformed matrix is composed by a distinct relationship between continuous-time gain and discrete-time gain, it is noted that the proposed method can be regarded as an explicit gain transformation method compared to the other methods using series expansion.

• Journal of Ubiquitous Convergence Technology
• /
• v.1 no.1
• /
• pp.28-34
• /
• 2007

Tree-based reliable multicast protocols provide scalability by distributing error-recovery tasks among several repair nodes. These repair nodes perform local error recovery for their receiver nodes using the data stored in their buffers. We propose a packet loss patterns adaptive feedback scheduling scheme to manage these buffers in an efficient manner. Under our scheme, receiver nodes send NAKs to repair nodes to request packet retransmissions only when the packet losses are independent events from other nodes. At dynamic and infrequent intervals, they also send ACKs to indicate which packets can be safely discarded from the repair node's buffer. Our scheme reduces delay in error recovery because the requested packets are almost always available in the repair node's buffers. It also reduces the repair node's workload because (a) each receiver node sends infrequent ACKs with non-fixed intervals and (b) their sending times are fairly distributed among all the receiver nodes.

• Proceedings of the KIEE Conference
• /
• 1998.07b
• /
• pp.506-508
• /
• 1998

In this paper, the optimal digital redesign is studied within the framework of fuzzy systems and dual-rate sampling control theory. An equivalent fast-rate discrete-time state-space model of the continuous-time system is constructed by using fuzzy inference systems. To obtain the optimal feedback gains developed in the continuous-time system, the constructed fuzzy system is converted into a continuous-time system. The developed continuous-time control law is converted into an equivalent slow-rate digital control law using the proposed digital redesign method. The digital redesign technique using a fuzzy model is employed to simulate the inverted pendulum dynamics.

• Proceedings of the KIPE Conference
• /
• 2000.07a
• /
• pp.620-623
• /
• 2000

A very simple control approach using neural network for the robust position control of a Permanent Magnet Synchronous Motor(PMSM) is presented The linear quadratic controller plus feedforward neural network is employed to obtain the robust PMSM system approximately linearized using field-orientation method for an AC servo. The neural network is trained in on-line phases and this neural network is composed by a fedforward recall and error back-propagation training. Since the total number of nodes are only eight this system can be easily realized by the general microprocessor. During the normal operation the input-output response is sampled and the weighting value is trained multi-times by error back-propagation method at each sample period to accommodate the possible variations in the parameters or load torque. And the state space analysis is performed to obtain the state feedback gains systematically. IN addition the robustness is also obtained without affecting overall system response. This method is realized by a floating-point Digital Singal Processor DS1102 Board (TMS320C31) The basic DSP software is used to write C program which is compiled by using ANSI-C style function prototypes.

• 제어로봇시스템학회:학술대회논문집
• /
• 1990.10a
• /
• pp.149-154
• /
• 1990

In this paper, simulation results of a robust digital tracking controller on a robotic manipulator are presented. The objective is to follow a ramp reference input with zero steady state error in the presence of a disturbance and system parameter variations. Some of the difficulties are caused by the Coulomb frictions, the disturbance due to the gravitational pull, the spring effect of a link between the drive motor and the manipulator arm. Another difficulty is that, because of the non-differentiable Coulomb friction, the digital control system cannot be represented as a discrete system. It is thus necessary to design the controller based on a discrete-continuous hybrid model. The controller is based on feeding back the state variables and augmenting the system by addition discrete integrators. The feedback gain parameters are obtained by applying the quadratic optimal control theory and then choosing the new weighting matrices to eliminate the limit cycle by using the describing function method for hybrid system.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.49 no.4
• /
• pp.246-255
• /
• 2000

This paper deals with a novel full digital control method of the three-phase PWM inverter for UPS. The voltage and current of output filter capacitor as state variables are the feedback control input. In addition, a double deadbeat control consisting of a d-q current minor loop and a d-q voltage major loop, both with precise decoupling, have been developed. The switching pulse width modulation based on SVM is adopted so that the capacitor current should be exactly equal to its reference current. In order to compensate the calculation time delay, the predictive control is achieved by the current·voltage observer. The load prediction is used to compensate the load disturbance by disturbance observer with deadbeat response. The experimental results show that the proposed system offers an output voltage with THD less than 2% at a full nonlinear load.

• Journal of Power Electronics
• /
• v.14 no.6
• /
• pp.1322-1333
• /
• 2014

To track the sinusoidal current under stationary frame and suppress the effects of low-order grid harmonics, the multi-resonant quasi-proportional plus resonant (PR) controller has been extensively used for digitally controlled LCL-type pulse-width modulation (PWM) converters with capacitor-current-feedback active damping. However, designing the controller is difficult because of its high order and large number of parameters. Moreover, the computation and PWM delays of the digitally controlled system significantly affect damping performance. In this study, the delay effect is analyzed by using the Nyquist diagrams and the system stability constraint condition can be obtained based on the Nyquist stability criterion. Moreover, impact analysis of the control parameters on the current loop performance, that is, steady-state error and stability margin, identifies that different control parameters play different decisive roles in current loop performance. Based on the analysis, a simplified controller design method based on the system specifications is proposed. Following the method, two design examples are given, and the experimental results verify the practicability and feasibility of the proposed design method.