DC Servo Research Articles

Stability criterion for networked control systems with additive time-varying state-delays and bounded nonlinearity

In this paper, a robust delay-dependent stability criterion is presented for a class of networked control systems with additive time-varying state-delays and bounded nonlinear perturbations using Lyapunov-Krasovskii LK functional approach. In the proposed delay-dependent stability analysis, to reduce conservatism, a candidate LK functional is considered, and the time-derivative of the functional is bounded using reciprocal convex combination lemma. The proposed stability analysis eventually culminates into a stability criterion in LMI framework that can be solved readily using standard numerical packages. The effectiveness of the proposed stability criterion is illustrated using a standard numerical example and a network controlled DC servo system.

Two Improved Cancellation Techniques for Direct-Conversion Receivers

To solve the problems of carrier leakage and DC offset in direct-conversion receiver (DCR) system, the paper proposed two kinds of improved technology to overcome the problems in DCR system. One is the RF carrier cancellation technology; the traditional cancellation technology based on lumped parameter filter can be easily influenced by distribution parameters, the improved circuits use a 3 db bridge to realize a 180-degree phase shifter, and the method can adapt to a wider range of RF frequency. Another is DC offset cancellation technique; a novel DC servo loop circuit is proposed to replace the traditional AC-coupled amplifier circuit. It can improve the integrity of the baseband signal and reduces the complexity of the subsequent software algorithm. Experimental results show that two kinds of improved technology can improve the performance of DCR and expand its scope of application.

Demonstrative DC Motor Control under Power Communication Network

Power line communication (PLC) has been used to transmit and receive digital data via power line in wide application. However, power lines weren’t built for data transmission originally. In practice, data transmission is commonly subjected to switching noise by the multi-path effect. The objective of this research is to establish a platform for easily tune the controller for motor control system under the PLC environment. We build up a dynamic model to simulate the power line environment for communication and propose a frequency-shift keying (FSK) technique to modulate and demodulate the signal for the purpose of network control in the disturbed feedback control loop. A modified proportional-integralderivative controller (PID controller) on positioning control a DC servo motor is proposed to against noise corruption while achieving tracking performance.

Two-Channel sEMG Controller for Electric Hand Gripper: Amputee Hand Training Device

This research aims to design and develop the two-channel surface electromyography (sEMG) control unit for an electric hand gripper, projected for amputee hand training device. The intention of this medical device is to use it before using the prosthetic hand. The amputee hand training device has developed based on the principle of physiology, biomedical electronics and microcontroller. The prototype consisted of three main units: signal detector and signal conditioning modules, signal control and processing components using the ATMEL 328 microcontroller, and the 2-Degrees of Freedom (DoF) electric hand gripper with DC servo motors. The performance testing was done by the users controlled the 2-DoF electric hand gripper using their sEMG signal. The functional assessment results showed that the success rate of grasping accuracy of the three main basic geometries were 93% of cylinder, 90% of cubic and 40% of egg. The success rate of the rotation of a wrist hand was 83%. Each calculation was calculated for 30 times in performing its specific function. The production cost of this medical device was around £165.

Flow-induced vibration of an elastically mounted airfoil under the influence of the wake of a circular cylinder

The effect of vortices generated by a rigidly mounted cylinder on the dynamic response of an airfoil is investigated in this study. This work extends previous investigation of vortex interaction with a second cylinder to capture the wake energy (Derakhshandeh et al. 2014). Accordingly, the Flow-Induced Vibration (FIV) of a symmetric NACA 0012 airfoil positioned in the wake of the rigidly-mounted upstream cylinder is studied. The airfoil mount allows it to move in two degrees-of-freedom; pitch and heave. The pitching axis is kinematically driven using a brushless permanent-magnet DC servo motor. The heave axis of the airfoil is coupled with a Virtual Elastic Mechanism (VEM), which is an electro-mechanical device designed to create any desired impedance. The VEM system replaces the physical damper and spring systems and allows the airfoil to oscillate due to the lift force in the normal direction of the flow. The airfoil is set at different positions in the wake of the upstream cylinder in order to characterise the impact of the arrangement of a coupled cylinder–airfoil on energy extraction. Special attention was paid to the angle of attack of the airfoil to explore the optimal performance of the system. Force and displacement measurements of the airfoil were conducted in a closed loop water channel. The experimental work was complimented by a Computational Fluid Dynamics (CFD) modelling study which was aimed at calculating the vortex frequency shedding and visualize the vortex structure. It is observed that the vortex shedding frequency, the length scale and transverse spacing of the vortices are function of the longitudinal and lateral distances between the cylinder the airfoil. The results also demonstrate that there is a correlation between the configuration of cylinder and airfoil and vortex structure. Due to this correlation, the shear forces acting on the airfoil alters the fluttering response of the airfoil depending on the angle of attack, which in turn influences the obtained power coefficient of the device. The maximum power coefficient of FIV is obtained for cases with 3.5⩽x0/D⩽4.5 and 1⩽y0/D⩽1.5 arrangements, which is limited to the narrower lateral distances as compared to the previous study (1⩽y0/D⩽2) by the authors (Derakhshandeh et al. 2014) employing a pair of cylinders.

Pulse-Width Modulated Amplifier for DC Servo System and Its Matlab Simulation

This paper introduces a mathematical model for Pulse-Width Modulated Amplifier for DC Servo Motor. The relationship between pulse-width modulated (PWM) signal and reference rotation speed is specified, and a general model of motor represented by transfer function is also put forward. When the input signal changes, the rotation speed of the servo motor will change accordingly. By changing zeros and poles, transient performance of this system is discussed in detail, and optimal ranges of the parameters is recommended at the end of discussion.

Integral Sliding Mode Control of DC Servo-Driven Conveyor System

DC servo systems which are utilized in many industries require efficient and robust control strategies for achieving specific duties accurately. An integral sliding mode control (ISMC) is designed for position control of DC servo-driven conveyor system in this work. The ISMC which maintains the robustness, linearization and systematic design procedure of the conventional sliding modes is aimed to solve robust position control problem under load uncertainties. Performance and robustness of the ISMC are compared with the PID controller. Numerical and experimental results are presented to demonstrate the validity, feasibility and effectiveness of the designed control technique.

Patient-Driven Hand Exoskeleton Based Robotic with Active Control System for Early Post Stroke Rehabilitation

The development of a robotic exoskeleton to restore and rehab, hand and finger function is highly competitive nowadays. The robotic exoskeleton is an active actuated mechanism implemented in rehabilitation system, in which each finger attached to an instrumented lead screw mechanism allowing force and position control, according to the normal human setting. The robotic device is a direct driven actuated based on ergonomics measurements, capable to assist in flexion and extension motion. As an adaptation mechanism, it's also compatible with various sizes and shapes of anthropometric human‘s finger. The integration of DC servo motor and lead screw mechanism were the main features of the interface, which allows independent motion of the five fingers with small and lightweight actuators. The device is easily transportable, efficient safety performance, user friendly and offer multiple modes of training potentials. This paper presents the measurements implemented in the system to determine the requirements for finger and hand rehabilitation device, the design and characteristic of the whole system.

Fully Integrated Biopotential Acquisition Analog Front-End IC.

A biopotential acquisition analog front-end (AFE) integrated circuit (IC) is presented. The biopotential AFE includes a capacitively coupled chopper instrumentation amplifier (CCIA) to achieve low input referred noise (IRN) and to block unwanted DC potential signals. A DC servo loop (DSL) is designed to minimize the offset voltage in the chopper amplifier and low frequency respiration artifacts. An AC coupled ripple rejection loop (RRL) is employed to reduce ripple due to chopper stabilization. A capacitive impedance boosting loop (CIBL) is designed to enhance the input impedance and common mode rejection ratio (CMRR) without additional power consumption, even under an external electrode mismatch. The AFE IC consists of two-stage CCIA that include three compensation loops (DSL, RRL, and CIBL) at each CCIA stage. The biopotential AFE is fabricated using a 0.18 µm one polysilicon and six metal layers (1P6M) complementary metal oxide semiconductor (CMOS) process. The core chip size of the AFE without input/output (I/O) pads is 10.5 mm2. A fourth-order band-pass filter (BPF) with a pass-band in the band-width from 1 Hz to 100 Hz was integrated to attenuate unwanted signal and noise. The overall gain and band-width are reconfigurable by using programmable capacitors. The IRN is measured to be 0.94 µVRMS in the pass band. The maximum amplifying gain of the pass-band was measured as 71.9 dB. The CIBL enhances the CMRR from 57.9 dB to 67 dB at 60 Hz under electrode mismatch conditions.

MODEL-BASED SYSTEMS ENGINEERING OF A HAND REHABILITATION DEVICE

We have developed a robotic exoskeleton to restore and rehab hand and finger function. The robotic exoskeleton is a hybrid actuated mechanism rehabilitation system, in which each finger is attached to an instrumented lead screw mechanism allowing force and position control according to the normal human setting. The robotic device, whose implemented is based on biomechanics measurements, able to assist the subject in flexion and extension motion. It also compatible with various shapes and sizes of human‘s finger. Main features of the interface include an integration of DC servo motor and lead screw mechanism which allows independent motion of the five fingers with small actuators. The device is easily transportable, user safety precaution, and offer multiple mode of training potentials. This paper presents the measurements implemented in the system to determine the requirements for finger and hand rehabilitation device, the design and characteristic of the whole system.

MPPT of Magnus Wind System with DC Servo Drive for the Cylinders and Boost Converter

This paper presents an algorithm MPPT (Maximum Power Point Tracking) for a Magnus wind system with a DC servo drive system (DC drive and BLDC motor) to rotate the turbine cylinders. The optimal cylinders rotation is the one to deliver the maximum power extracted from the wind tracked by fixed and adaptive step HCC (Hill Climbing Control) acting on the servo drive. The proposed wind system consists of a PMSG (Permanent Magnet Synchronous Generator), a three-phase diode rectifier, a DC/DC (boost) converter, and a resistive load. Furthermore, the boost converter acts with the fixed step HCC algorithm to track the maximum power operating point. Therefore, the MPPT for a Magnus wind system requires both tracking for the optimal cylinder speed and the optimal generator speed.

Analog front-end measuring biopotential signal with effective offset rejection loop.

This paper presents an analog front-end (AFE) IC design for recording biopotential signals. The AFE employs a capacitively coupled instrumentation amplifier to achieve a low-noise and high-common mode rejection ratio (CMRR) system. A ripple reduction loop is proposed to reduce the ripple generated by the up-modulating chopper. The low frequency noise is attenuated by an input AC coupling capacitor, and is attenuated again by a DC servo loop. The proposed AFE features a differential gain of 71 dB, and a CMRR of 89 dB, at 50 Hz. Furthermore, the proposed AFE can robustly acquire biopotential signals even in the presence of an input offset and ripples.

Reduction of Settling Time and Overshoot for Flyback Converter by Using Modern Optimization Based PI Controller Driven DC Servo Motor

In this study, a simple PI controller is presented for regulation of the output voltage of the DC to DC fly back converter driven DC Servo motor with constant frequency. Here a new PI control algorithm implemented in FPGA has been proposed for optimizing the PI parameters using PSO and ABC optimization techniques. A comparison has been made between the two optimization algorithms across different load and voltage variations and their effectiveness in reduction of overshoot and settling time of fly back converter in DC Servo motor drive have been evaluated.

PEMANFAATAN MOTOR SERVO SEBAGAI PENGGERAK CCTV UNTUK MELIHAT ALAT-ALAT MONITOR DAN KONDISI PASIEN DI RUANG ICU

Ahmad Hilal, Saiful Manan, in paper use servo motor as a CCTV driver to see monitoring equipment and conditions of patients in the icu room explain thatservo motor is a motor with a closed feedback system in which the position of the motor will be communicated back to the control circuit in the servo motor, servo motor is able to work both directions (clockwise and belawanan clockwise) in which the direction and angle of the rotor movement can controlled only by providing PWM signal duty cycle settings on the control pin. In the servo motor function of this type is only capable of moving in either direction (CW and CCW) with respective deflection angle reaches 90 ° so that the total deflection angle of the center - right -kiri adalah180 °. Part of the servo motors consist of a potentiometer which functions as a regulator of the servo movement of a large pulse is given, the internal gear serves as a torque amplifier dc servo motors, dc motors as the driving part that converts electrical energy into motion, as well as a control circuit servo motor driver function to process the data input pulses into motion. Servo motors used to drive the CCTV, in order to see the health of the patient monitoring devices as instructed. The servo motor voltage of 5 volts dc power supply from PC. Servo motor movements influenced the input pulse, to round to the right then it takes the pulse of more than 1,5ms, for the leftist movement takes the pulse of less than 1,5ms and at the center position or silence takes input pulse of 1.5 ms with a delay of 20 ms. Servo motors work processes in order to move that the serial data input from the PC, the serial data into the ATMEGA 8 for processing, so that the serial data is converted into binary data through IC74595 as servo motor driver, to output one of IC74595, the servo motor can move, because inflows along with pulses to the servo motor control circuit. Keywords: DC servo motors, Power Supply, IC74595, ATMEGA 8

Study of wire tension control system based on closed loop PID control in HS-WEDM

Wire electrical discharge machining (WEDM) is widely used in mould and die manufacturing, but the low machining accuracy limits its further developments, especially for high-speed wire electrical discharge machining (HS-WEDM) because of its non-even wire tension. A constant tension can restrain the high-frequency vibration of wire electrode effectively, which can improve the accuracy of workpiece surface. In this paper, a wire tension control system is designed to reduce the wire tension fluctuation, according to the process characteristic of HS-WEDM. Wire tension control system adopts a closed-loop control strategy. A mathematical model of control system is built based on DC servo motor, linear motion platform, and tension sensor. Meanwhile, a simulation model of transfer function is built to calculate proportion integration differentiation (PID) control parameters. Simulation results show that the calculated PID control parameters can satisfy the requirements of the control system. A series of experiments are designed to test the stability and reliability of wire tension control system and its workability. The value of wire tension fluctuation has been down by almost half with wire tension control system. The surface roughness of workpiece with wire tension control system is almost 0.6 μm lower than that without wire tension control system, which implies that this control system can improve the quality of parts manufacturing for HS-WEDM.

Comparision of Perturb and Observer and Incremental Conductance MPPT Based Solar Tracking System.

This paper presents a detailed analysis of the two most well-known hill-climbing maximum power point tracking (MPPT) algorithms: the perturb-and-observe (P&O) and incremental conductance (INC). The purpose of the analysis is to clarify some common misconceptions in the literature regarding these two trackers, therefore helping the selection process of MPPT Keywords—Perturb and Observer, Incremental Conductance, Microcontroller, DC Servo motor. Maximum Power Point Tracking (MPPT) I. In tro d uct io n A photovoltaic system is a system which uses one or more solar panels to convert solar energy into electricity. The solar cell is the basic unit of a PV system. An individual solar cell produces direct current and power typically between 1 and 2 W, hardly enough to power most applications. It consists of multiple components, including the photovoltaic modules, mechanical and electrical connections and mountings and means of regulating and or modifying the electrical output. PV cells are made of semiconductor materials, such as silicon (2). For solar cells, a thin semiconductor wafer is specially treated to form an electric field, positive on one side and negative on the other.

날개 끝 회전자를 이용한 양력강화기법에 관한 연구

In order to verify the lift enhancement of the 2D hydrofoil with trailing edge rotor and check the ability of its practical use, experimental studies were conducted in the caviation tunnel using the test model with NACA0020 section. The three-component forces acting on the model could be measured by exclusively designed sting type multi-component load cell. The trailing edge of the model has been replaced with rotor which could be controlled by DC servo motor installed at the exterior of the tunnel. A typical effect of the trailing edge rotor has been introduced among the systematic experiments on various angular deviation of the model and the rotational velocity of the trailing edge rotor. It is appeared that the circulation control effect could be easily adjusted by selecting the rotational velocity of the trailing edge rotor and the lift force was augmented more than two times. Thus the proposed lifting device could be utilized as a novel high lifting device which has adjustability of lift force.

A 1.83 μJ/Classification, 8-Channel, Patient-Specific Epileptic Seizure Classification SoC Using a Non-Linear Support Vector Machine.

A non-linear support vector machine (NLSVM) seizure classification SoC with 8-channel EEG data acquisition and storage for epileptic patients is presented. The proposed SoC is the first work in literature that integrates a feature extraction (FE) engine, patient specific hardware-efficient NLSVM classification engine, 96 KB SRAM for EEG data storage and low-noise, high dynamic range readout circuits. To achieve on-chip integration of the NLSVM classification engine with minimum area and energy consumption, the FE engine utilizes time division multiplexing (TDM)-BPF architecture. The implemented log-linear Gaussian basis function (LL-GBF) NLSVM classifier exploits the linearization to achieve energy consumption of 0.39 μ J/operation and reduces the area by 28.2% compared to conventional GBF implementation. The readout circuits incorporate a chopper-stabilized DC servo loop to minimize the noise level elevation and achieve noise RTI of 0.81 μ Vrms for 0.5-100 Hz bandwidth with an NEF of 4.0. The 5 × 5 mm (2) SoC is implemented in a 0.18 μm 1P6M CMOS process consuming 1.83 μ J/classification for 8-channel operation. SoC verification has been done with the Children's Hospital Boston-MIT EEG database, as well as with a specific rapid eye-blink pattern detection test, which results in an average detection rate, average false alarm rate and latency of 95.1%, 0.94% (0.27 false alarms/hour) and 2 s, respectively.

Heat assisted recording on bottom layer of dual recording layer perpendicular magnetic recording media for two and a half dimensional (2.5D) magnetic data storage

In this paper, we present a study on two and a half dimensional (2.5D) perpendicular magnetic recording (PMR) media consisting of dual hard magnetic recording layers (RL) with 1st or top RL1 used for conventional data storage and 2nd or bottom RL2 used for dedicated servo with lower linear densities or DC servo patterns with focus on the writability issue of the bottom servo layer (RL2). We demonstrate experimentally the feasibility to magnetically erase, write, and re-write RL2 by laser assist on a home built heat-assisted-magnetic-recording writing test system. Experimental data (by magnetic force microscopy measurements) show that the signal amplitudes of the pre-recorded magnetic patterns for both RL1 and RL2 decrease at almost the same rate with thermal erasure using scanning laser power (Pw) from 13 mW to 23 mW, clearly indicating equally effective laser heating and close temperature rise for RL1 and RL2 for far field laser heating with laser pulse duration in sub-μs and μs range. This is further verified by theoretical simulations of the thermal distribution and the temperature rise depth profile in dual layer media by laser heating. Simulations indicate very little temperature difference of less than 6 K (∼1% of maximum temperature rise) between RL1 and RL2 because the main mechanism of temperature rises in RL1 and RL2 is due to the effective thermal conduction from the top layers to lower layers. These experimental and theoretical study results could provide useful understanding and insights into servo writing methods of 2.5D PMR media.

Discrete-Time Exponentially Stabilizing Fuzzy Sliding Mode Control via Lyapunov’s Method

The exponentially stabilizing state feedback control algorithm is developed by Lyapunov’s second method leading to the variable structure system with chattering free sliding modes. Linear time-invariant discrete-time second order plant is considered and the control law is obtained by using a simple fuzzy controller. The analytical structure of the proposed controller is derived and used to prove exponential stability of sliding subspace. Essentially, the control algorithm drives the system from an arbitrary initial state to a prescribed so-called sliding subspaceS, in finite time and with prescribed velocity estimate. Inside the sliding subspaceS, the system is switched to the sliding mode regime and stays in it forever. The proposed algorithm is tested on the real system in practice, DC servo motor, and simulation and experimental results are given.