Mohamed B. Trabia

A TWO-STAGE FUZZY LOGIC CONTROLLER FOR TRAFFIC SIGNALS

This paper presents the design and evaluation of a fuzzy logic traffic signal controller for an isolated intersection. The controller is designed to be responsive to real-time traffic demands. The fuzzy controller uses vehicle loop detectors, placed upstream of the intersection on each approach, to measure approach flows and estimate queues. These data are used to decide, at regular time intervals, whether to extend or terminate the current signal phase. These decisions are made using a two-stage fuzzy logic procedure. In the first stage, observed approach traffic flows are used to estimate relative traffic intensities in the competing approaches. These traffic intensities are then used in the second stage to determine whether the current signal phase should be extended or terminated. The performance of this controller is compared to that of a traffic-actuated controller for different traffic conditions on a simulated four-approach intersection.

Generalized Design of an Anti-swing Fuzzy Logic Controller for an Overhead Crane with Hoist

The behavior of many mechanical systems, such as overhead cranes, can be predicted through intuitive observation of their motion under various forces. Mathematical modeling of an overhead crane shows that it is highly coupled. Nonetheless, it is surprisingly easy for an experienced crane operator to drive payloads to target positions with minimal cable swing. This observation naturally promotes the use of fuzzy logic to control overhead cranes. Traditionally, fuzzy logic controllers of overhead cranes were presented for specific crane system/motion parameters. This work presents a novel approach for automatically creating anti-swing fuzzy logic controllers for overhead cranes with hoisting. The model of the crane includes the distributed mass of the cable. The presented approach uses the inverse dynamics of the overhead crane and the desired motion parameters to determine the ranges of the variables of the controllers. The control action is distributed among three fuzzy logic controllers (FLCs): The travel controller, hoist controller, and anti-swing controller. Simulation examples show that the proposed controller can successfully drive overhead cranes under various operating conditions.

A Hybrid Fuzzy Simplex Genetic Algorithm

This paper presents a novel hybrid genetic algorithm that has the ability of the genetic algorithms to avoid being trapped at local minimum while accelerating the speed of local search by using the fuzzy simplex algorithm. The new algorithm is labeled the hybrid fuzzy simplex genetic algorithm (HFSGA). Standard test problems are used to evaluate the efficiency of the algorithm. The algorithm is also applied successfully to several engineering design problems. The HFSGA generally results in a faster convergence toward extremum.

Adaptive path planning and obstacle avoidance for a robot with a large degree of redundancy

A new algorithm for path planning and obstacle avoidance for redundant planar robots is proposed. The task of path planning is formulated as a sequence of nonlinear programming problems. For each problem, the objective is to minimize the distance between the current location of the end-effector and a desired location. Two penalties are added to each objective function to ensure that the robot is not colliding with any obstacle and that its links are not crossed over. The effects of mechanical stops and limits for maximum joint movements are also incorporated as inequality constraints. The algorithm uses an adaptive scheme to activate the fewest number of the outboardmost joints, and none of the inboard ones if possible, to reach a desired location. The algorithm is especially useful when the number of joints is large.

Modeling of Ionic Polymer Metal Composite Actuator Dynamics Using a Large Deflection Beam Model

This paper introduces a novel technique for modeling the dynamics of ionic polymer metal composites (IPMCs). The proposed finite element modeling technique combines a large deflection beam model and lumped RC model. In this approach, a local coordinate frame attached at the first node of each element which undergoes rigid body motion and elastic deformation of the element is described with respect to the local coordinate frame. The proposed model accounts for the large elastic deflection of each element. This modeling strategy has the advantage of accurately describing the large deformation of the IPMC using a limited number of elements. Experimental results are found to be in close agreement with those of simulating the proposed model.

A General Anti-swing Fuzzy Controller for an Overhead Crane with Hoisting

Several fuzzy control schemes of overhead cranes have been proposed. Most of these schemes are valid for a specific crane configuration only. Extensive experimentation is needed to apply such schemes to a different crane. This paper presents an approach for automatically creating anti-swing fuzzy logic controllers for two-dimensional overhead cranes with hoisting. Inverse dynamics and desired motion parameters of the overhead crane are used to determine the ranges of the variables of the controllers. The control action is divided into two phases. In the first phase, two fuzzy logic controllers (FLCs) drive the system toward its final destination: travel controller and hoist controller. The second phase is initiated after this point. It includes an anti-swing controller in addition to the travel and hoist controllers. The simulation example presented shows that the proposed controller can successfully drive overhead cranes under various operating conditions.

Steering fuzzy logic controller for an autonomous vehicle

Autonomous vehicles can be used in variety of applications such as hazardous environment or intelligent highway system. Fuzzy logic seems to be an appropriate choice for this area. This paper proposes a fuzzy logic controller for steering an autonomous vehicle toward a target. The controller is divided into separate modules to mimic the way humans think while driving. One module drives the vehicle toward the target while another is used to avoid collision with obstacles. A separate module is designed to drive the vehicle through mazes. The last module adjusts the final orientation of the target. The paper contains several examples to demonstrate the interaction between the several modules of the controller.

Design of a Compact Ceramic High-Temperature Heat Exchanger and Chemical Decomposer for Hydrogen Production

This article describes a compact silicon carbide ceramic, high-temperature heat exchanger for hydrogen production in the sulfur iodine thermochemical cycle, and in particular, to be used as the sulfuric acid decomposer. In this cycle, hot helium from a nuclear reactor is used to heat the SI (sulfuric acid) feed components (H2O, H2SO4, SO3) to obtain appropriate conditions for the SI decomposition reaction. The inner walls of the SI decomposer channels are coated with platinum to catalytically decompose sulfur trioxide into sulfur dioxide and oxygen. Hydrodynamic, thermal, and the sulfur trioxide decomposition reaction were coupled for numerical modeling. Thermal results of this analysis are exported to perform a probabilistic mechanical failure analysis. This article presents the approach used in modeling the chemical decomposition of sulfur trioxide. Stress analysis of the design is also presented. The second part of the article shows the results of parametric study of the baseline design (linear channels). Several alternate designs of the chemical decomposer channels are also explored. The current study summarizes the results of the parametric calculations whose objective is to maximize the sulfur trioxide decomposition by using various channel geometries within the decomposer. Based on these results, a discussion of the possibilities for improving the productivity of the design is also given.

Modelling and control of an overhead crane with a variable length flexible cable

This paper introduces a novel mathematical model that represents an overhead crane with flexible cable and load hoisting/lowering. The model includes the transverse vibrations of the flexible cable. Highly non-linear Partial Differential Equations and Ordinary Differential Equations that govern the motion of the crane system within the time-varying spatial domain are derived via calculus of variation and Hamiltons principle. A proportional derivative control scheme is applied to drive the underlying crane so that the cable and payload swing are damped out. Numerical simulations for the control performance of the considered system are presented for various operating conditions.

Dynamic Modeling of Segmented Ionic Polymer Metal Composite (IPMC) Actuator

In this paper, we introduce an analytical modeling approach for dynamic shape characterization of the ionic polymer metal composite (IPMC) actuator under the input voltages based on the RC electrical model and mechanical beam model. The proposed method can be used for modeling the general IPMC bending actuator in a single segment or multiple segments or patterned form. The segmented design offers more flexibility in controlling the shape of the actuator when compared with the single-segment design as it can be used to generate undulatory wave form instead of a simple oscillation form. Considering the inherent nature of large deformation in the IPMC actuator, a large deflection beam model is developed and augmented with the electrical RC model to present a state space model of the actuator system. Experimental results are compared with the computer simulated IPMC actuator model to validate the proposed model