Ashok Nedungadi

Parallel hybrid drivetrain

A hybrid vehicle includes an internal combustion engine, an electric motor/generator and a battery. The drivetrain includes a planetary gear in which the engine is coupled to the sun gear, the motor/generator to the ring gear and the vehicle wheels to the carrier of the planetary. A controller switches the vehicle between electric, assist, charge and regenerative modes of operation and substantially decouples the engine speed from the vehicle speed, enabling the engine to operate at peak efficiency. Additional overdrives are included to enable the engine to operate at optimum speed in the various modes of operation.

A fuzzy robot controller-hardware implementation

The author developed a robot controller that exploits the principles of fuzzy logic to circumvent the mathematically complex inverse kinematic equations that are at the heart of operations of conventional robot controllers. The fuzzy control rules are derived for a planar robot with an arbitrary number of serial degrees of freedom. Computer simulation results are presented to verify the proposed concept. In addition, the hardware implementation of the fuzzy robot controller is described and experimental results are included.<<ETX>>

A novel approach to robot control using fuzzy logic

The authors have developed a robot controller that exploits the principles of fuzzy logic to circumvent the mathematically complex inverse kinematic equations that are at the heart of operations of conventional robot controllers. They describe the derivation of the fuzzy control rules for a planar robot with an arbitrary number of serial degrees-of-freedom (DOF). Computer simulation results are presented to verify the proposed concept. In addition, experimental results of implementing the developed fuzzy logic controller on a four DOF planar laboratory robot are discussed. Bench mark tests comparing the execution speed of the proposed fuzzy logic controller with the traditional controller revealed that the approach described was 33% times faster than traditional methods, which require solution of the inverse kinematic equations.<<ETX>>

A Fuzzy Logic-Based Robot Controller

Conventional robot controllers rely on an exact inverse kinematic model to convert user-specified Cartesian trajectory commands to joint set points. These inverse kinematic equations are robot specific and form a set of highly coupled nonlinear equations that pose a considerable computational bottleneck. It is not uncommon for the host CPU to dedicate as much as 80% of its computational resources to solve the inverse kinematic equations alone. Further, the strictly mathematical nature of the inverse kinematic equations results in kinematic singularities in which the robot is uncontrollable. These drawbacks have resulted in current robot controllers being limited in flexibility with respect to adaptive control, kinematic redundancy, and obstacle avoidance. This observation provided the impetus to investigate the applicability of fuzzy logic to resolve the computational bottleneck of the inverse kinematic module. In the following, an approach is presented based on fuzzy logic, which replaces the computationally intensive inverse kinematic equations and lays the foundation for a robot controller with a simpler architecture. A hardware implementation of a fuzzy logicbased robot controller is described in which simple fuzzy rules replace the complex inverse kinematic equations. The implemented fuzzy robot controller was tested on a planar four-degree-of-freedom lab robot. Hardware test results of the lab robot tracking arbitrary trajectories are discussed.

Life-Cycle Cost Sensitivity to Battery-Pack Voltage of an HEV

A detailed component performance, ratings, and cost study was conducted on series and parallel hybrid electric vehicle (HEV) configurations for several battery pack and main electric traction motor voltages while meeting stringent Partnership for a New Generation of Vehicles (PNGV) power delivery requirements. A computer simulation calculated maximum current and voltage for each component as well as power and fuel consumption. These values defined the peak power ratings for each HEV drive system’s electric components: batteries, battery cables, boost converter, generator, rectifier, motor, and inverter. To identify a superior configuration or voltage level, life cycle costs were calculated based on the components required to execute simulated drive schedules. These life cycle costs include the initial manufacturing cost of components, fuel cost, and battery replacement cost over the vehicle life.

A test of long-term, predictive, geochemical transport modeling at the Akrotiri archaeological site

Abstract A study of elemental transport at the Akrotiri archeological site on the island of Santorini, Greece, has been conducted to evaluate the use of natural analog data in support of long-term predictive modeling of the performance of a proposed geologic repository for nuclear waste at Yucca Mountain, Nevada. Akrotiri and Yucca Mountain have many analogous features including silicic volcanic rocks, relatively dry climates, and oxidizing, hydrologically unsaturated subsurface conditions. Transport of trace elements from artifacts buried in volcanic ash 3600 years ago at Akrotiri is analogous to transport of radioactive wastes in the proposed repository. Subtle evidence for a plume of Cu, Zn, and Pb has been detected by selective leaching of packed earth and bedrock samples collected immediately beneath the site where bronze and lead artifacts were excavated. The geologic setting of the artifacts and the hydraulic properties of the enclosing media were characterized. A numerical model of the type used in repository performance assessments was developed for elemental transport at the site. Site characterization data were used to build the model but no prior information on the nature of the contaminant plume was provided to the modelers. Some model results are qualitatively consistent with field data, including the small amount of material transported, limited amounts of sorbed material, and relatively elevated sorption on a packed earth layer, However, discrepancies result from incomplete representation of heterogeneity and complexity and poorly constrained model parameters. Identification of such system characteristics and model limitations in relevant systems is a major contribution that analog studies can contribute in support of repository modeling.

Modeling future automobiles: the role of industry and government

The Partnership for a New Generation of Vehicles (PNGV) is a joint project of the “big three” US automakers and seven US government agencies. The goal of the partnership is to develop a mid‐sized car with a fuel economy of 3 liter/100km. The US Department of Energy is supporting the development of two computer codes for modeling future automobiles. PNGV and similar government/industry partnerships elsewhere in the world, some of them formed in response to PNGV, are bringing major changes – perhaps a revolution – in automobiles. The 30 years of experience by the electromagnetics modeling community may be able to contribute to this process of change.

Sensor integrated control for manipulators

Shortcomings of commercial robot controllers are discussed from the perspective of several advanced robotic applications, in which there are specific needs for dynamic manipulator motion control based on sensor inputs. Experiences with systems using sensor-based control of process parameters, manipulator motions, and manipulator paths are described. Particular attention is given to the adaptive control of lightweight robot arms. Requirements for sensor integrated control are presented on the basis of these experiences, and features and capabilities that should be included in manipulator controllers for future applications are discussed. Some of the unexpected problems that come about due to sensor integration are examined.<<ETX>>