Yaojung Shiao

An expert system for fault diagnosis in internal combustion engines using probability neural network

An expert system for fault diagnosis in internal combustion engines using adaptive order tracking technique and artificial neural networks is presented in this paper. The proposed system can be divided into two parts. In the first stage, the engine sound emission signals are recorded and treated as the tracking of frequency-varying bandpass signals. Ordered amplitudes can be calculated with a high-resolution adaptive filter algorithm. The vital features of signals with various fault conditions are obtained and displayed clearly by order figures. Then the sound energy diagram is utilized to normalize the features and reduce computation quantity. In the second stage, the artificial neural network is used to train the signal features and engine fault conditions. In order to verify the effect of the proposed probability neural network (PNN) in fault diagnosis, two conventional neural networks that included the back-propagation (BP) network and radial-basic function (RBF) network are compared with the proposed PNN network. The experimental results indicated that the proposed PNN network achieved the best performance in the present fault diagnosis system.

Development of a multi-pole magnetorheological brake

This paper presents a new approach in the design and optimization of a novel multi-pole magnetorheological (MR) brake that employs magnetic flux more effectively on the surface of the rotor. MR brakes with conventional single ring-type electromagnetic poles have reached the limits of torque enhancement. One major reason is the limitation of the magnetic field strength within the active area of the MR fluid due to the geometric constraints of the coil. The multi-pole MR brake design features multiple electromagnetic poles surrounded by several coils. As a result, the active chaining areas for the MR fluid are greatly increased, and significant brake torque improvement is achieved. The coil structure, as a part of the stator, becomes flexible and customizable in terms of space usage for the winding and bobbin design. In addition, this brake offers extra options in its dimensions for torque enhancement because either the radial or the axial dimensions of the rotor can be increased.Magnetic circuit analysis was conducted to analyze the effects of the design parameters on the field torque. After that, simulations were done to find the optimal design under all major geometric constraints with a given power supply. The results show that the multi-pole MR brake provides a considerable braking torque increase while maintaining a compact and solid design. This is confirmation of its feasibility in actual braking applications.

Fault diagnosis for internal combustion engines using intake manifold pressure and artificial neural network

This paper describes an internal combustion engine fault diagnosis system using the manifold pressure of the intake system. The manifold pressure of the engine intake system always demonstrates the engine condition and affects the volumetric efficiency, fuel consumption and performance of internal combustion engines. Manifold pressure is well known to be detrimental to engine system stability and performance and it must be considered during regular maintenance. Conventional engine diagnostic technology using manifold pressure in intake system already exists through analyzing the differences between signals and depends on the experience of the technician. Obviously, the conventional detection is not a precise approach for manifold pressure detection when the engine in operation condition. In the present study, a system consisted of manifold pressure signal feature extraction using discrete wavelet transform (DWT) and fault recognition using the neural network technique is proposed. To verify the effect of the proposed system for identification, both the radial basis function network (RBFN) and generalized regression neural network (GRNN) are used and compared in this study. The experimental results indicated the proposed system using manifold pressure signal as data input is effective for engine fault diagnosis in the experimental engine platform.

Design of an Innovative High-Torque Brake

The paper shows the design of an innovative magneto-rheological fluid brake (MRF brake). The integral brake torque from a conventional MRF brake is not quite large since it commonly adopts a single ring-type electromagnetic pole to produce magnetic flux to change the MRF viscosity. This presented innovative MRF brake features with multiple electromagnetic poles to significantly increase the active chaining areas for MRF, and then increase the brake torque. Because of the special arrangements of pole numbers and directions of magnetic flux for these poles, the active chaining areas of MR fluid and brake force are maximized. The simulation results confirmed the feasibility and ability of this innovative MRF brake. Performance comparison shows that the innovative MRF brake has 118% more torque output than a commercial one.

Optimal design of a new multipole bilayer magnetorheological brake

This article presents a new high-torque multipole bilayer magneto-rheological brake (MRB). This MRB has a unique structural design with multiple electromagnetic poles and multiple media layers of magnetorheological fluid (MRF). The MRB has two rotors located on the outer and inner sides of a six-pole stator, and therefore, it can provide higher torque and a larger torque-to-volume ratio (TVR) than conventional single- or multipole single-layer MRBs can. Moreover, the problem of potential MRF leakage is solved by using cylindrical separator rings around the stator. In this study, first, the structure of the proposed MRB is introduced. An analog magnetic circuit was built for the MRB to investigate the effects of the MRB parameters on the magnetic field intensity of the MRF layers. In addition, a 3D electromagnetic model of the MRB was developed to simulate and examine the magnetic flux intensity and corresponding braking torque. An approximate optimization method was then applied to obtain the optimal geometric dimensions for the major dimensional parameters of the MRB. The MRB was manufactured and tested to validate its torque and dynamic characteristics. The results showed that the proposed MRB exhibited great enhancement of the braking torque and TVR.

A Study of Novel Hybrid Antilock Braking System Employing Magnetorheological Brake

A novel hybrid antilock braking system (ABS) with the combination of auxiliary brake and a multipole magnetorheological (MR) brake was proposed in this paper. The MR brake with innovative operation concept can replace existed hydraulic brake system or works as an auxiliary brake. Two simulation models of the MR brakes, inner rotor and outer rotor structures, have been built. The outer rotor design was chosen due to its better braking performance and suitable mechanism for using on motorcycle. After that, motorcycle simulation software was employed to validate the hybrid ABS system under appropriated working condition. Two controllers, the ordinary and self-organizing fuzzy logic controllers (FLC and SOFLC), were evaluated on ABS performance to pick the suitable one. Simulation results confirm the more adaptations to different road conditions of the SOFLC with 18% higher brake performance compared to ones of ordinary FLC. Brake performance can increase 12% more with the combination of SOFLC and road condition estimator (RCE). It is concluded that this hybrid ABS is feasible for actual application by effectively improving the brake performance for ensuring driving stability.

Actuator control for a new hybrid electromagnetic valvetrain in spark ignition engines

Valve timings of a spark ignition engine have been limited to a narrow range of alternatives within the constraints of the fuel economy, the emissions and the dynamic performance. Variable valve timing shows promise as a new key technology for improving the fuel consumption and emissions of spark ignition engines. Several techniques have been developed to perform variable valve timing, and the method with the most potential, called a hybrid electromagnetic valvetrain actuator, is an electromagnetic valvetrain with a permanent magnet and electromagnetic coils installed together. In this study, a novel hybrid electromagnetic valvetrain with a permanent magnet and electromagnetic coils, which significantly differs from existing electromagnetic valvetrains, was designed to overcome the drawbacks of conventional electromagnetic valvetrains that have been introduced previously. This new hybrid electromagnetic valvetrain is characterized by a simple structure, simple actuation and an ultra-low actuating power. Magnetic simulation was applied to analyse the magnetic flux density of the electromagnetic valvetrain and to optimize the design parameters. Dynamic simulation results show that the proposed hybrid electromagnetic valvetrain with soft-landing control can fully satisfy the valve dynamics in spark ignition engines. Additionally, the utilization of a permanent magnet and an optimal actuating current to catch and release valves has many advantages in energy consumption for valve catching and releasing when compared with other electromagnetic valvetrains.

Design and validation of outer rotor magnetorheological brake with multiple poles

Abstract A magnetorheological brake with multiple poles and an outer rotor structure is introduced in this paper. It is designed to be used as a resistant source for bicycle training equipment. The outer rotor structures works as a roller against the bike rear wheel for indoor exercise. The key factors to affect the brake torque were found after an analysis of the magnetic circuit of the brake. Two structures with different pole numbers were simulated to find the optimal one which harmonises between the maximum output torque and the input power. Simulation results confirm the feasibility of the outer rotor magnetorheological brake concept. The optimal brake was later manufactured and experimented for validation. Its torque can be controlled precisely by an input current with a very fast response. The maximum brake torque is 5 Nm at a 0·9 A input current. Those phenomena are applicable for the bicycle training equipment. Moreover, the compact design of the brake shows advantages in weight and space reductions.

Design of a Novel Damping-Controllable Damper for Suspension Systems

Conventional oil dampers are non-controllable passive dampers because the viscosity of the fluid used is not wide-range variable. By using magneto-rheological fluid (MRF), MRF damper has excellent performance for variable-damping applications. Due to the single-coil design in the general MRF damper, the obtained damping from MR effect is not quite large. This research provides a high-damping MRF damper by adopting multi-pole coil and special polarization configuration. The simulated results show that the new MRF damper has good performance in the magnetic field and damping. Compared with a similar-size general single-coil MRF damper, this new MRF damper can get 47% higher performance under the same operating conditions.

Design and Experiment of the Magnetorheological Damper with Multiple Poles

The main function of a suspension system is to isolate and absorb the impact from road surface to vehicle body. To provide good riding comfort, a damper with variable and wide-range damping is highly needed. This paper presents a complete procedure from design, optimization to experiment for a magnetorheological (MR) damper with multiple poles. This new designed damper is entirely different from those conventional single-pole MR dampers, effectively by extending the range of damping force. Magnetic simulation has been done in the paper to provide an optimal structure of the damper which significantly enhances the damping force while avoids magnetic saturation. The new damper was also manufactured and tested. The experimental results show that the provided damping force can be significantly increased with the increase of input current from low to high speeds. Damping force can be varied by 7.41 times. It proves that this new MR damper with high damping force can be controlled adaptively at wide range of operation conditions. It is suitable to be an adaptively variable damping source in semi-active suspension systems.