Shuanghui Hao

Study on a novel absolute magnetic encoder

Compared with an optical encoder, structure of magnetic rotary encoder is very simple and not affected in dust and mist condition, can be used in badly condition. But its resolution and accuracy are low and difficult to be improved by conventional methods. In order to improve the resolution of magnetic encoder, a novel encoder structure and signal processing method base on calibration are present. A radial magnetizing ring alnico is adhered to rotor of motor, while six Hall ICs are placed around the alnico evenly to sense magnetic field produced by the alnico. Magnetic encoder is calibrated using a higher resolution incremental optical encoder off-line: angle output from optical encoder and voltage from Hall ICs were sampled at the same time and transmitted to PC, relation between them can be get and stored in the ROM of MCU for look up table. Angle can be get according to voltages of Hall ICs. Magnetic encoder is designed and its accuracy can achieve to 13-bits. Its structure is very simple and cost is very low compare with an optical encoder. It can be used in most occasions.

Research on the Thermal Error of the 3D-Coordinate Measuring Machine Based on the Finite Element Method

3D-coordinate Measuring Machine (CMM) is affected by various heat sources in high-speed measuring, which results in deformation of the machine and measurement errors. This paper makes a theoretical analysis on the thermal error produced during the CMMs work process. And the thermal deformation of CMM is analyzed with Finite Element Method (FEM). A thermal error compensation model is also established by multi-body theory. Meanwhile integral mean value theorem is used to establish a mathematical model of the thermal expansion of the drive screw, and the CMM measurement accuracy is improved.

A High-performance Speed Feed-forward Controller for Permanent Magnet Synchronous Motor Based on Control System Model

Abstract This study proposes a feed-forward controller based on a control system model that can precisely track a reference trajectory by canceling out the effects of parameter uncertainties on a surface-mounted (magnets glued to the shaft surface) permanent magnet synchronous motor. Furthermore, the speed tracking control algorithm demands rapid and accurate q-axis current command, so the feed-forward system based on the control model is used to estimate it. The stability of the proposed controller is mathematically studied. The proposed control scheme is executed on a permanent magnet synchronous motor drive using a Renesas micro-control unit (RX62TADFFM, Japan). Finally, simulation and experimental results are presented to verify that the proposed controller achieves less steady-state error, better robust performance, and faster dynamic response than the proportional–integral controllers in the presence of permanent magnet synchronous motor parameter uncertainties and external load torque disturbance.

Autonomous control of electromagnetic aircraft launch system based on decentralized architecture

So far, there is no research achievement of using the Autonomous decentralized control (ADC) technology to control the super high power motor of the electromagnetic aircraft launch system (EMALS). In this paper, we propose an autonomous decentralized system and algorithm for this control problem. We first analyse the architecture of the EMALS autonomous control model, then design a autonomous decentralized algorithm which is performed on the experimental model system. And we propose the fault-tolerance design. The experimental result shows that this method is effective for motor control, its highly fault-tolerant and allowing the distributed power transmission which can reduce the power of the power source.

A new method of simulation and development for digital controlled AC servo system

An integrated simulation and development environment for the digital controlled AC servo system is proposed in this paper, which is based on personal computer to be applied to simulate, optimize and adjust the control code and control parameters of system without any hardware. Its an exploration for improving the digital controlled AC servo systems developing condition. In this paper, the arithmetic of RPN and Runge-Kutta are introduced in detail. And then, the validity and the feasibility of environment are verified by simulation and experimental results. Also, through combining exhaust algorithm with the closed-loop simulation environment, parameter optimization can be implemented. In this paper, proportion coefficient and integral time constant of PID control are optimized and good performance is achieved.

A study on the model of 3D-coordinate Measuring Machine dynamic characteristic

Additional inertial force will cause the deformation of some parts when 3D-coordinate Measuring Machine (CMM) runs quickly. It will result in the difference between real results and reading of raster sensor, that is, dynamic error will be produced. This paper presents the theoretical model of CMM dynamic error compensation. The Z-direction deformation of crossbeam is analyzed based on Ansys, one kind of finite element simulation software, when slide carriage is in different position under three different load conditions (accelerating, uniform speed, decelerating). Dynamic error compensation model is acquired under any kind of load according to the analysis results, which can improve the measuring accuracy of CMM greatly.

An applied CNC acceleration and deceleration control algorithm research

In this paper, S-shape acceleration and deceleration control algorithm by use of equivalent trapezoid acceleration and deceleration is employed to satisfy the need of high-speed machining. The proposed algorithm has better to solve the shortcoming of the usual S-curve acceleration and deceleration control algorithm which the judgment condition is complicated comparatively and moreover must be analyzed seven stages respectively. At the same time, the problem of the intersection speed being processed smoothly between continuous small path sections can also be solved by use of the change rate of feed-rate vector interpolation to confine the acceleration of the intersection in this paper. The algorithm is effective and has been realized on the newly developed CNC simulation system based on code interpretations.

Design of high precision magnetic grid displacement sensor

A new kind of magnetic grid displacement sensor is designed in this paper, which is composed of magnetic head and magnetic grid. The magnetic head contains arrays of linear hall element, and the magnetic grid is made of arrays of permanent magnet. In order to enhance the quality of original voltage signal, the signal generator adopts three-phase and six components. The errors caused by assemble and zero drift is eliminated through difference. Otherwise, the electromagnetic field of magnetic signal generator is analyzed with ANSYS. The assemblage gap of magnetic head can be chosen better according to the analysis result, which can improve the signal quality also. A look-up table technique is presented when dealing with magnetic grid signal, which can decreases the computational complexity of the processing chip. And the method is realized through the flush type SCM(dsPIC33FJ64MC706) with 16 bits. The peripheral circuit is simplified, which meets the requirement of miniaturization and increases the resolution and reliability of the magnetic grid displacement sensor.

Adaptive gain scheduling with feedforward control system based on system model for PMSM

ABSTRACT A feedforward controller for permanent magnet synchronous motor (PMSM) has been proposed in this study, and proportional and integral gain could be self-adaptive under different operating conditions. The control structure used in the feedforward system is the same as in the feedback control system. This control structure could guarantee independence of the speed command input to output with the disturbance input to output, which makes the system have better reference trajectory tracking and disturbances rejection. In order to obtain optimal control performance when the parameters are uncertain, a gain scheduling adaptive controller is used in the feedforward system. The proposed controller has been verified by the experimental and simulation results with less steady-state error and better dynamic response than the controllers without it under the condition of external load torque disturbance and PMSM parameter uncertainties.

Study on high precision magnetic encoder based on PMSM sensorless control

Purpose To eliminate the angle deviation of magnetic encoder, this paper aims to propose a compensation method based on permanent magnet synchronous motor (PMSM) sensorless control. The paper also describes the experiments performed to verify the validity of this proposed method. Design/methodology/approach The proposed method uses PMSM sensorless control method to get high precision virtual angle value, and then get the deviation value between virtual position and magnetic angle which is used as compensation table. Oversampling linear interpolation tabulation method has been proposed to eliminate the noise signals. Finally, a magnetic encoder with precision (repeatability) 0.09° and unidirectional motion precision 0.03 is realized. The control system with an encoder running at 14,000 and 0.01 r/min showing high motion resolution is also realized. Findings Higher value of current in PMSM leads to a magnetic encoder with higher precision. When using oversampling linear interpolation to tabulate the compensation table, it is understood that more oversampling does not lead to a better result. Finally, validated by experiments, using eight intervals to calculate the mean value of angle deviation leads to the best result. Practical implications The angle deviation compensation method proposed in this paper has a great practical implication and a good commercial application. The method proposed in this paper could be effectively used to self-correct the magnetic encoder using arctangent method and also correct any rotary encoder sensor. Originality/value This paper originally proposes an adaptive correction method for a rotary encoder based on PMSM sensorless control. To eliminate the noise signals in an angle compensation table, over-sampling linear interpolation tabulation method has been proposed which also guarantees the precision of the compensation table.