Jian Fei Pan

High-precision position control of a novel planar switched reluctance motor

This paper presents the position control of a novel two-dimensional (2-D) switched reluctance (SR) planar motor. The planar motor consists of a six-coil moving platform and a flat stator base made from laminated mild steel blocks. Unlike conventional x-y tables, which stack two moving slides on top of each other, the proposed 2-D planar motor has the advantages of simple mechanical construction, high reliability, and the ability to withstand harsh operating conditions. Together with the two linear encoders attached to the x-axis and y-axis, the motor can be controlled under closed-loop mode. To combat the problem of force nonlinearity, this paper proposes a cascade controller with force linearization technique to implement the drive controller. Due to the unique structure of the planar motors magnetic circuit, there is very little coupling between the x-axis and y-axis, and no decoupling compensation is needed. Preliminary results show that the proposed SR planar motor has a positional accuracy of 5 /spl mu/m and a maximum acceleration/deceleration rate of 2 G.

A Self-Tuning Regulator for the High-Precision Position Control of a Linear Switched Reluctance Motor

In the high-technology mass manufacturing industry, high-speed and high-precision motion is an indispensable element in the automated production machines. In recent years, there has been a growing tendency to employ direct drive permanent magnet linear synchronous motors in demanding motion applications. Although the overall performance is good, its implementation cost remains high. This is mostly due to the cost of the Neodymium-Boron magnets, the manufacturing of the magnetic rails, and the precision of the overall mechanics. In this paper, a much cheaper alternative is proposed-to use a low-cost linear switched reluctance motor (LSRM) and an adaptive control strategy to overcome the tolerances and difficult control characteristics inherent in the motor. The LSRM has simple and robust structure, and it does not contain any magnets. However, its force is solely drawn from the reluctance change between the coil and the steel plates. Variations on the behavior of these two elements due to different operating conditions will change the motion behavior of the motor. Also, to keep the overall cost low, the LSRM sets a marginal mechanical tolerance during its mass production. This leads to characteristic variations in the final product. Finally, since the LSRM is a direct drive motor, any variations on the motor characteristics will directly reflect on the control system and the motion output. In this paper, a self-tuning regulator (STR) is proposed to combat the difficulties and uncertain control behaviors of the LSRM. This paper first introduces the motor winding excitation scheme, the model of the LSRM, and the current control method. The LSRM system is modeled as a single-input single-output discrete model with its parameters estimated by the recursive least square (RLS) algorithm. Then, an STR based on the pole placement algorithm is applied to the LSRM for high- performance position tracking. Both the simulation investigation and the experimental verification were conducted. In both cases, the results verified that the proposed RLS algorithm can estimate the parameters with fast convergence. The STR can provide quick response and high precision which is robust to the change of system parameters. Combined with STR control, the LSRM is a low-cost solution to fast, accurate, and reliable position tracking for many demanding motion control applications.

Design and simulation of a magnetic levitated switched reluctance linear actuator system for high precision application

Magnetic levitated carrier system was developed for the transportation systems. It is contact-free type; it can eliminate mechanical components (e.g. gears, guide, ball bearings), reduce the mechanical alignment and maintenance cost, satisfy environmental demand, and enable the carrier to travel at high speed with high precision and acceleration. In this paper, the investigation, design, simulation and fabrication of a magnetic levitated linear motion system are addressed, based on switched reluctance (SR). The proposed system resolves the problems of mechanical wear, friction, noise, heat generation, and ldquometal dustrdquo contamination, and it is very suitable for applications that require high-performance linear motions: from high-precision manufacturing machines, clean-room wafer carrier systems, to high-speed material transportation in factories and warehouses. The proposed system employs a novel linear machine structure which uses four coils for levitation, and three coils for propulsion. Comparing to permanent-magnet (PM) track levitation, high-temperature superconductor levitation, and other existing magnetic levitation methods, the proposed system has a much simpler structure. It can lower manufacturing cost and increase reliability. In this paper, we firstly discussed the mechanical structure of the proposed levitation system and the model of the actuators. Then, finite element analysis (FEA) was carried out for both the propulsion and levitation actuators to verify the electromagnetic characteristics of the motion system. Finally, a control algorithm, which includes PID and nonlinear force control was discussed. The levitation system was simulated by Matlab Simulink, to achieve a stable and high-precision position control. The simulation results were very satisfactory and it validated the design concept.

A Novel Planar Switched Reluctance Motor for Industrial Applications

This paper presents a novel two-dimensional (2-D) planar switched reluctance motor (PSRM) for position control applications. The proposed 2-D planar motor has the advantages of simple mechanical construction, high reliability, and the ability to withstand hostile operating conditions. Due to the unique structure of the planar motors magnetic circuit, there is very little coupling between the X- and Z-axis, and no decoupling compensation is needed. It is expected that this innovative SR planar motion system will be an ideal replacement for traditional X-Y tables in industrial automation applications

Distributed Coordinated Motion Tracking of the Linear Switched Reluctance Machine-Based Group Control System

The coordinated tracking control for the group motion control system based on three direct-drive double-sided linear switched reluctance motors (LSRMs) is investigated in this paper. The system construction for the proposed coordinated tracking system is elaborated, including the unit system and group system design, communication configuration among unit systems, and stability and performance analysis of the group system. The coordinated control performance is concentrated on three identical LSRMs with different communication topologies. Experimental results demonstrate that necessary bidirectional interactions between the unit systems contribute to the coordination performance. The maximum dynamic tracking error within ±0.4 mm can be achieved under the sinusoidal reference of 30-mm amplitude and 0.2-Hz frequency.

Deformation and Noise Mitigation for the Linear Switched Reluctance Motor With Skewed Teeth Structure

In this paper, a skewed teeth structure is proposed for the linear switched reluctance motor (LSRM). First, the normal force, as the main source of the machine deformation as well as the acoustic noise, is analyzed theoretically. Second, the skewed LSRM is designed, and the angle of the skewed structure is analyzed and optimized. Then, the normal force output of the LSRM is calculated using the finite element method (FEM), and the deformation results for the proposed machine are obtained. The relationship of the normal force and the skewed angle is derived. Finally, the experimental results demonstrate that the acoustic noise is reduced, which is a testament to the effectiveness of the proposed structure.

Collaborative Tracking Control of Dual Linear Switched Reluctance Machines Over Communication Network With Time Delays

This paper investigates the collaborative tracking control for dual linear switched reluctance machines (LSRMs) over a communication network with random time delays. Considering the spatio-temporal constraint relationship of the dual LSRMs in complex industrial processes, the collaborative tracking control scheme is proposed based on the networked motion control method. The stability conditions and the controller design method for the networked dual LSRMs are obtained from the two motors relative position error by using Lyapunov theory and delay systems approach. Four different allocation schemes combined with two kinds of external control signals are applied onto the collaborative tracking control experiment platform of the dual LSRMs to validate the effectiveness of the proposed method. The maximum steady-state relative position error within 0.104 mm can be achieved under the constant absolute position reference input signal of 3 mm, and the maximum absolute relative position error within ±0.46 mm can be achieved under the sinusoidal reference of 8 mm amplitude and 0.2 Hz.

Robust control for a networked direct-drive linear motion control system

This paper investigates the robust control method for networked dynamic systems and its application for a direct-drive linear motion control system in a network environment. The unavoidable network-induced random delays are modeled as Markov chains. The control object of the linear motion control system in this study is a double-sided linear switched reluctance machine (DLSRM). To tackle the inherent uncertainties in the DLSRM, a robust control strategy is designed by proposing a new Lyapunov function and applying the free-weighting matrix technique. A state feedback robust controller is designed such that the closed-loop direct-drive linear motion control system over a network is stochastically robust stable. The robust controller can be conveniently obtained by solving a set of linear matrix inequalities. The numerical simulation of an angular positioning system is presented to illustrate the effectiveness of the proposed robust control method. Furthermore, the experimental tests on the networked direct-drive linear motion control system verify the practicability of the proposed method.

High-Precision Dual-Loop Position Control of an Asymmetric Bilateral Linear Hybrid Switched Reluctance Motor

In this paper, to enhance the machine performance and realize a high-precision position control performance, a dual-loop position controller is employed for the asymmetric bilateral linear hybrid switched reluctance motor (ABLHSRM). Machine characteristics are investigated by finite-element method. The dual-loop controller is constructed by employing a tradition proportional-integral differential velocity controller as the inner loop and a fuzzy proportional differential (PD) controller for the outer loop. Experimental results demonstrate that both the position control performance and the velocity control performance under the dual-loop control algorithm are superior to the single-loop PD position control strategy. An absolute steady-state error of 4 μm can be achieved under the dual-loop control strategy. Performance comparison from the ABLHSRM and its asymmetric bilateral linear switched reluctance counterpart with the same dimensions are carried out. Position tracking results show that the rise time is improved for the proposed ABLHSRM under the proposed control scheme.

Mixed H2/H∞ control of markovian jump time-delay systems with uncertain transition probabilities

This study addresses the robust stability problem of Markovian jump time-delay systems with mixed H2 and H∞ control and uncertain transition probabilities in the discrete-time domain. The transition probabilities are considered to be uncertain but bounded. By proposing a new Lyapunov functional and applying the free-weighting matrix technique, we design the mode-dependent mixed H2/H∞ controller such that the resultant closed-loop systems possess stochastic stability and are prescribed with H∞ performance indices. These results generalize several results reported in previous literature, which consider the Markovian transition probabilities to be known a priori or partially unknown transition probabilities. Numerical examples and a practical motion control system are presented to illustrate the effectiveness of this technique.