A transient-enhanced NMOS low dropout voltage regulator with parallel feedback compensation

This paper presents a transient-enhanced NMOS low-dropout regulator （LDO） for portable applications with parallel feedback compensation. The parallel feedback structure adds a dynamic zero to get an adequate phase margin with a load current variation from 0 to 1 A. A class-AB error amplifier and a fast charging/discharging unit are adopted to enhance the transient performance. The proposed LDO has been implemented in a 0.35 μm BCD process. From experimental results, the regulator can operate with a minimum dropout voltage of 150 mV at a maximum 1 A load and IQ of 165 μA. Under the full range load current step, the voltage undershoot and overshoot of the proposed LDO are reduced to 38 mV and 27 mV respectively.

Magnetic Field Feedback Circuit for Geomagnetic Field Compensation Control

In the current state of geomagnetic instrument testing,some aspects of geomagnetic instrument performance are difficult to test in the laboratory.If laboratory test results are inadequate,the instrument will have multiple problems while operating in the field,where a geomagnetic instrumentation test platform with a stable natural magnetic field is critical.Here,the magnetic field feedback circuit for geomagnetic field compensation control is studied in detail.That is,the magnetic field measured by the feedback magnetic sensor and the required working magnetic field are compared as input to the system,and the electric signal is transmitted to the feedback coil through an analog circuit to form a closed loop control,which provides compensation to control the magnetic field.Compared with the existing magnetic shielding method,the analog control circuit can achieve the realization of any working magnetic field,and it is not limited to a null magnetic field.The experimental result shows that the system compensates the earth’s magnetic field of 10,000 nT with an average error of 10.6 nT and average compensation error of 0.106%,providing a high compensation accuracy.The system also shows high sensitivity and excellent stability.The feedback circuit has achieved effective compensation control for the earth’s magnetic field.

Improved Nonlinear Friction Compensation Method for Robot Joint Driving

In order to alleviate the steady-state position error and the destabilizing effect of the nonlinear friction, a novel compensation method is presented, which modified the traditional Southward's compensation method. Estimated the nonlinear friction model using an identification method, the effect caused by its nonlinear component can be compensated, and an enhanced tracking performance is verified on a selectively compliant articulated robot arm(SCARA) robot.

A Study on the Dynamic Performance of Hydroviscous Driyes

Gives a dynamic mathematical model of a typical type of multiple discs hydroviscous drive device which has been proved to be correct through tests.Utilizing the method of root-locus analysis the dynamic performance of this device is studied according to the model.Theoretical analysis and test re- suits show that the dynamic performance of the object of study can be greatly improved by speed negative feedback.

Precision and Flexible Bending Control Strategy Based on Analytical Models and Data Models

Forming of various customized bending parts,small batches,as well as numerous types of materials is a new challenges for Industry 4.0,the current control strategies can not meet the precision and flexibility requirement,expected control strategy of bending processes need to not only resist unknown interferences of process condition and models,but also produce various new parts automatically and efficiently.In this paper,a precision and flexible bending control strategy based on analytical models and data models is proposed to build adaptive bending systems.New analytical prediction models for loading and unloading are established and suitable for various materials,a sequential identification strategy is proposed to search nominal properties using the four sub-optimization models.A data-based feedback model is established to prevent over-bending and eliminate online deviation.Above models are merged into a precision and flexible control strategy.The system firstly uses sub-optimization models to search the nominal point which is near to target point,secondly the system further uses feedback model to eliminate residual error between the nominal point and target point.Compared with four kinds sheet metals,the allowable ranges for variables are determined for a good convergence.The target bending angles were set to 20°,40°,and 60°.Forty parts were tracked for each kind material,the adaptive bending system converged after one iteration,and exhibited better performances.

Effects of Signal Spectrum Bandwidth on Different PMD Compensation Feedback Methods

We compared efficiencies of different PMD compensation feedback methods against transmission signal bandwidth, including NRZ, RZ, CRZ format under various duty cycles. We found that the critical factor determining the efficiency of PMD compensation is not the modulation format, but the spectral bandwidth of the transmission signal.

Robust Control for Static Loading of Electro-hydraulic Load Simulator with Friction Compensation

Load simulator is a key test equipment for aircraft actuation systems in hardware-in-the-loop-simulation. Static loading is an essential function of the load simulator and widely used in the static/dynamic stiffness test of aircraft actuation systems. The tracking performance of the static loading is studied in this paper. Firstly, the nonlinear mathematical models of the hydraulic load simulator are derived, and the feedback linearization method is employed to construct a feed-forward controller to improve the force tracking performance. Considering the effect of the friction, a LuGre model based friction compensation is synthesized, in which the unmeasurable state is estimated by a dual state observer via a controlled learning mechanism to guarantee that the estimation is bounded. The modeling errors are attenuated by a well-designed robust controller with a control accuracy measured by a design parameter. Employing the dual state observer is to capture the different effects of the unmeasured state and hence can improve the friction compensation accuracy. The tracking performance is summarized by a derived theorem. Experimental results are also obtained to verify the high performance nature of the proposed control strategy.

Tracking Control Design for Nonholonomic Mechanical Systems with Affine Constraints

The trajectory tracking control is considered for nonholonomic mechanical systems with affine constraints and dynamic friction. A new state transformation is proposed to deal with affine constraints, and then an integral feedback compensation strategy is used to identify the dynamic friction. The proposed controller ensures that the output tracking errors converge to zero as t →∞.As an application, a detailed example is presented to illustrate the effectiveness of the control scheme.