Sohair F. Rezeka

A new approach to evaluate instantaneous friction and its components in internal combustion engines

A new approach has been developed at Wayne State University to determine the instantaneous friction and its components in internal combustion engines. The method is based on the fact that the instantaneous cylinder gas forces and the instantaneous frictional, inertia and load forces cause the instantaneous variation in the flywheel angular velocity. The instantaneous total friction forces have been computed for a single diesel engine, under idling conditions. A breakdown of the friction into its components and a formulation for each component has been made. By applying linear regression, correlations between the individual components of the friction losses and the different parameters have been developed. The components are classified into two categories: piston assembly losses and crankcase assembly losses. The correlations have been applied to a multi-cylinder and a single cylinder diesel engine to compute frictional losses under operating and motoring conditions. The computed results have been found to be in a fairly good agreement with the experimental results. The correlations were also applied to the gasoline engine and compared with published experimental results in the literature.

A Diagnostic Technique for the identification of Misfiring Cylinder(s)

This paper introduces a diagnostic technique for the detection of misfiring cylinders in internal combustion engines. The technique requires the analysis of the instantaneous angular velocity of an engine flywheel. The results show that the mean cyclic acceleration, maximum variation in angular velocity, and the cyclic period of acceleration can be used as a measure for the mean net torque and the mean net expansion pressure torque produced by each cylinder. The proposed technique has proven to be effective in identifying a faulty cylinder using efficient and simple computations.

A feedforward neural network for the automatic control of a four-wheel-steering passenger car

An automatic control system using a feedforward neural network is proposed for four-wheel-steering passenger cars to mimic the behavior of human driver. The control system consists of two identical two-layer-feedforward networks and a feedback of the car heading deviation. One neural network acts as an emulator, and the second represents a feedforward controller. The synaptic weights of the networks are adjusted according to the generalized adaline weight adaptation algorithm. The duration of the general learning was 500 s, and no measurements were acquired. Computer simulation was carried out to evaluate the performance of the proposed system in tasks involving lane keeping on a curved roadway at different speeds, gusting side wind, and an obstacle-avoidance maneuver. The results showed that the system displayed good driving performance, and was capable of reproducing the steering performance of human driver. The system realized rapid, comfortable, and stable responses in the different tasks.

Modeling and sensitivity analysis of an ABS hydraulic modulator

The components of the hydraulic modulator of an anti-lock braking system (ABS) are modeled using the bond graph methodology. The analysis includes the solenoid valve, the return pump, and the accumulator. The inputs are the pressure exerted from the brake master cylinder and the commands of the electronic control unit (ECU). The bond graph is analyzed and the state equations, that describe the modes of operation, are derived and solved numerically. Sensitivity analysis is applied to investigate the influence of the design parameters on the dynamics of the 3/3 solenoid valve. The results show that during the pressure build-up mode, the initial forces in both the main and auxiliary springs are the major parameters that affect the opening of the intake valve. During the pressure reduction period, the armature dynamics are sensitive to the armature mass and to the auxiliary spring stiffness. The influence of mechanical friction on the armature motion can be conceivably strong in the case of armature block. The volume of flow to the wheel-brake cylinders depends mainly on the capacitance of the brake. This volume is sensitive to both the hydraulic resistance and the size of the filters.

A hierarchical neuro-fuzzy system for identification of simultaneous faults in hydraulic servovalves

This paper addresses the problem of identifying either single or simultaneous faults that may practically occur in hydraulic servovalves. A hierarchical neuro-fuzzy system is proposed to deal with the complex data and the interference between the phenomenological features of the faults. The proposed system decomposes the task of identification into three manageable subtasks. A mechanism of information abstraction from each stage is implemented. Data clustering and offline hybrid training are used to construct the rule base and the network structure. The suggested system was applied to identify simulated faults and compared with the single-stage system available in the literature. It was found that the hierarchical system is capable of detecting the faults through the whole tested range while the single inference system cannot deal with the complex data. The proposed diagnostic scheme offers a simple design procedure and high feasibility. It was also shown that appropriate architecture and associated knowledge structure affect the accuracy of results.

Fuzzy logic control of active magnetic bearing

This work addresses the feasibility of fuzzy logic control of active magnetic bearing in order to suppress the vibration of the shaft while running at the critical speeds. Three fuzzy controllers were synthesized. The first controller uses the displacements at the bearings as inputs, while the second controller includes the displacements as well as the change of displacements at the bearings as inputs. The third is a fuzzy proportional integral controller. The capability of the controllers, to compensate the losses occurred in the operating current, were tested. The results showed that the fuzzy proportional integral controller eliminates the shaft deflections but its performance was degraded as the operating current losses increased. The other two fuzzy controllers resulted in an acceptable performance with respect to the damping of the shaft deflections. They were also capable to compensate up to 40% of the current losses. The commonly used proportional derivative controller rendered the worst dynamic performance as compared to the fuzzy controllers.

Supervisory position control for wheeled mobile robot

This paper focuses on the design of supervisory position control system for the Wheeled Mobile Robot (WMR) called Robotino. The target is to perform a position control using the behavior-base control strategy. The main advantage of this strategy is the division of the complex control task into sub simple tasks. The suggested supervisory system is a PC based and is designed using Lab VIEW software instead of the Robotino View software. Lab VIEW has many advantages like good graphical user interface and could be linked and integrated with other specialized software or different robotic systems. The simulation of the proposed system based on the deduced kinematic model of the Robotino WMR is carried out. Moreover, the proposed system is implemented practically on the Robotino WMR. The simulation and experimental results have shown an enhanced behavior with an acceptable performance.

Quantitative Robust Control of Temperature and Humidity in Hot-and-Dry Climates

In dry and hot weather, both temperature and humidity control should be adopted in buildings, industrial plants, and passenger cars. Because of the unsatisfactory performance of the available classical control system, a quantitative servo controller is synthesized in this paper. The proposed feedback controller is constructed by a state observer related to the plant and utilizing the measured room temperature and humidity as an input. The robustness properties of such a system to model error are discussed. The feasibility of both the synthesized and the conventional control systems are investigated in the presence of uncertainty in both the room internal loads and the outside load. The introduced controller is found capable of adjusting the room temperature and humidity at the design values for all time.