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This study aims to analyze the accuracy for feasibility study of Network-RTK(VRS) surveying inside and outside of Korean CORS network. The southwest coast of Korea where some part of mainland and islands are outside of CORS network is chosen as the test area. To evaluate the accuracy of VRS surveying at surveying points, several Unified Control Points (UCPs) inside and outside of Korean CORS network were selected as the points in the test area. The feasibility of VRS surveying was analyzed by investigating the errors related to the location of points inside and outside of CORS network and the difference of 3-dimensional coordinates observed on different date. As the results of this study, the orthometric height errors of points outside of CORS network based on KNGeoid14 were improved about 5.0 cm in RMSE in comparison with KNGeoid13. The height errors of VRS surveying were considered to be less relevant to the results from PDOP and number of satellites (GPS and GLONASS). However, the orthometric errors caused by the geoidal height of KNGeoid and the ellipsoidal height of VRS surveying at points located outside of CORS network need to be addressed carefully for control surveying. When a point surveyed twice on different date, the difference of the ellipsoidal height of the point outside of CORS network was larger than that of the point inside of CORS network.

This paper addresses a real-time grasp synthesis of multi-fingered robot hands to find grasp configurations which satisfy the force closure condition of arbitrary shaped objects. We propose a fast and efficient grasp synthesis algorithm for planar polygonal objects, which yields the contact locations on a given polygonal object to obtain a force closure grasp by a multi-fingered robot hand. For an optimum grasp and real-time computation, we develop the preference and the hibernation process and assign the physical constraints of a humanoid hand to the motion of each finger. The preferences consist of each sublayer reflecting the primitive preference similar to the conditional behaviors of humans for given objectives and their arrangements are adjusted by the heuristics of human grasping. The proposed method reduces the computational time significantly at the sacrifice of global optimality, and enables grasp posture to be changeable within 2-finger and 3-finger grasp. The performance of the presented algorithm is evaluated via simulation studies to obtain the force-closure grasps of polygonal objects with fingertip grasps. The architecture suggested is verified through experimental implementation to our developed robot hand system by solving 2- or 3-finger grasp synthesis.

Two adaptive nonlinear control schemes are presented for an induction motor: tuning function and modular design approaches. The objective here is to control the speed and flux in an independent manner despite rotor resistance uncertainty. In most existing adaptive schemes with this objective, load torque is regarded as a constant but unknown parameter to be estimated rather than a disturbance. On the other hand, this paper uses an integrator to deal with the low-frequency load torque instead of trying to estimate it. Simulations show that the proposed adaptive schemes lead to uniform closed-loop performance despite the uncertainty of the rotor resistance.

A novel model reference adaptive control (MRAC) scheme for electrical servo drives is proposed, in which the control input is synthesized without any parameter identification mechanism and a PI controller is inserted ahead of the plant to reduce the steady state chattering. The proposed scheme is shown to be asymptotically stable in case that load torque disturbance sati sfies a certain condition. An application to a permanent magnet synchronous motor drive shows that the output error between the plant and the reference model tends to zero and the chattering is greatly reduced.

When electronic ballasts are used for fluorescent lamps, lifetime of the lamp is greatly affected by starting scenario and crest factor. A new method to reduce the crest factor of the lamp is proposed, and the proposed electronic ballast is controlled in the mode of pulse frequency modulation (PFM). Electronic ballasts with 50% valley-fill PFC are dealt with in this paper. The characteristics of electronic ballast with the proposed PFM control scheme are comprehensively investigated through several simulations and experiments.

Online efficiency control optimization of induction motor drives is important from the viewpoints of energy saving and controlling a system whose characteristics are not fully unknown. The paper presents a neural network-based online efficiency control optimization for an induction motor drive which adopts slip angular frequency control. In the proposed scheme, a neurocontroller adjusts the slip angular frequency adaptively for minimum loss operation based on the measured input power. Simulation results show that considerable energy savings are achieved in comparison with the conventional method of operating under the condition of constant voltage to frequency ratio.

In this paper, we consider a dynamics of actuator driving system as well as actuator itself to design a robust adaptive controller for robot manipulators. We propose an adaptation law to guarantee the boundedness of parameter estimates irrespective of the boundedness of other closed-loop signals without data normalization. We also propose a control law to ensure the uniform stability of the closed-loop system without a priori knowledge of the unmodeled dynamics. We show that the tracking error belongs to the normalized error bound, and also show the robustness of the proposed adaptive controller by using an experiment referred to a two-link direct drive manipulator. >

The authors present a systematic study of an induction motor drive system employing a load commutated current source inverter (LCCSI). The steady-state characteristics of a LCCSI-fed induction motor are shown to be the intermediate characteristics between the voltage source inverter (VSI) and the auto sequentially commutated current source inverter (ASCI). The dynamic characteristics of the LCCSI-fed induction motor are investigated using a linearised model. A study through the pole/zero locations of the linearized system shows that a V/Hz ratio control loop plays an essential role in the stabilization of the system. >

A new control scheme using a torsional torque estimator based on a neural network is proposed and investigated for improving control characteristics of the high-performance motion control system. This control method presents better performance in the corresponding speed vibration response, compared with the disturbance observer-based control method. This result comes from the fact that the proposed neural network estimator keeps the self-learning capability, whereas the disturbance observer based torque estimator with the low pass filter should adjust the time constant of the adopted filter according to the natural resonance frequency determined by considering the system parameters varied. The simulation results show the validity of the proposed control scheme.

A synthesis method of the reduced-order extended Luenberger observer (ROELO) and its design procedure for a nonlinear dynamic system are presented. This paper proposes a method to reduce the order of the observer and to select the observer gain matrix. The main features of the proposed observer are discussed and compared with the characteristics of the other observers. The proposed algorithm is applied for high-performance induction motor drives without a speed sensor. The simulation results show that the proposed ROELO provides both the rotor flux and rotor speed estimation with good transient and steady state performance.

A method for designing a fault-tolerant control system with an additive redundant controller is presented. In the case when the main controller is a pole assignment controller and the redundant controller is an MRAC whose reference model is the closed-loop combination of the plant and the main controller, it is shown that the overall control system ensures the performance of set-point tracking even under failure in one of the two controllers. >

We derive a mathematical model of a single-stand cold rolling mill and design control systems to improve the thickness precision while maintaining prescribed tension for the strip. On the basis of a linearized model of the rolling mill system, we propose a thickness controller using an internal model control (IMC) structure which effectively rejects periodic disturbances. We also discuss how the so-called BISRA AGC method can be combined with the proposed thickness controller in the presence of modeling error. It is illustrated by simulations that the proposed thickness controller yields better performance than existing methods when a periodic thickness disturbance exists, and that it is robust to the uncertainty of the mill modulus.