Designing a fuzzy scheduler for hard real-time systems

In hard real-time systems, tasks have to be performed not only correctly, but also in a timely fashion. If timing constraints are not met, there might be severe consequences. Task scheduling is the most important problem in designing a hard real-time system, because the scheduling algorithm ensures that tasks meet their deadlines. However, the inherent nature of uncertainty in dynamic hard real-time systems increases the problems inherent in scheduling. In an effort to alleviate these problems, we have developed a fuzzy scheduler to facilitate searching for a feasible schedule. A set of fuzzy rules are proposed to guide the search. The situation we are trying to address is the performance of the system when no feasible solution can be found, and therefore, certain tasks will not be executed. We wish to limit the number of important tasks that are not scheduled

Situational reaction and planning

One problem faced in designing an autonomous mobile robot system is that there are many parameters of the system to define and optimize. While these parameters can be obtained for any given situation determining what the parameters should be in all situations is difficult. The usual solution is to give the system general parameters that work in all situations, but this does not help the robot to perform its best in a dynamic environment. Our approach is to develop a higher level situation analysis module that adjusts the parameters by analyzing the goals and history of sensor readings. By allowing the robot to change the system parameters based on its judgement of the situation, the robot will be able to better adapt to a wider set of possible situations. We use fuzzy logic in our implementation to reduce the number of basic situations the controller has to recognize. For example, a situation may be 60 percent open and 40 percent corridor, causing the optimal parameters to be somewhere between the optimal settings for the two extreme situations

Constant Thermodynamic Speed Simulated Annealing for the Traveling Salesman Problem

(Statement of Responsibility) by Nathan Pfluger(Thesis) Thesis (B.A.) -- New College of Florida, 1989(Electronic Access) RESTRICTED TO NCF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE(Bibliography) Includes bibliographical references.(Source of Description) This bibliographic record is available under the Creative Commons CC0 public domain dedication. The New College of Florida, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.(Local) Faculty Sponsor: Ruppeiner, Georg

A fuzzy logic approach to command arbitration for an autonomous mobile robot

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references.One of the ultimate goals in the field of robotics is to create autonomous robots. Such robots would be able to accept high level input commands from either a human operator or a centralized control system and perform that task with no outside influence. Ideally, the input commands would only specify what was needed to be done, not how. Developing an autonomous mobile robot requires studying and intergrating the concepts of autonomous sensing, reasoning, and control. One of the basic issues in autonomous reasoning, which has ramifications also in sensing and control, is that of motion planning. Mobile robot motion planning is the process of determining a set of steps for the robot to execute in order to achieve its goal position. In one of its simplest forms, motion planning involves computing a set of trajectories and speeds for the robot to take in order for it to arrive at its predetermined destination. There are many methods to accomplish this form of motion planning, but all have some drawbacks which could limit the capabilities of the robot. The major goal of this research has been to extend an approach developed by D. Payton and J. Rosenblatt which combines some of the best elements of previous approaches. Their research was in a behavioral approach which attempts to minimize information loss in command formulation by using a command arbitration network, termed command fusion. We have extended Payton-Rosenblatt's approach using fuzzy logic. The benefits of our approach include simplicity, extensibility and understandability in the command formulation process. Another contribution of this research has been to identify the limitations of existing defuzzification techniques for dealing with prohibitive information. We have developed a new defuzzification strategy that has been able to remedy this problem. Keywords:Fuzzy Logic, Fuzzy Control., Behaviors, Autonomous Mobile Robot

A Fuzzy Logic Based Extension to Payton and Rosenblatt's Command Fusion Method for Mobile Robot Navigation

David Payton and Ken Rosenblatt have recently proposed a command fusion method for combining outputs of multiple behaviors in a mobile robot navigation system such that information loss due to command fusion can be reduced. Using linguistic fuzzy rules to explicitly capture heuristics implicit in the Payton-Rosenblatt approach, we have extended their approach to a fuzzy logic architecture for mobile Published in: IEEE Transactions on Systems, Man, and Cybernetics, Vol 25, No. 6, pp. 971-978, June 1995. This research was supported by NASA Grant NGT-50837 and NSF Young Investigator Award IRI-9257293. Figure 1: Which way to turn? Obstacle avoidance does not know robot navigation in dynamic environments, which is simpler and easier to understand and modify. We have also developed and empirically tested a new defuzzification technique for alleviating difficulties in applying existing defuzzification methods to mobile robot navigation control. I. Introduction The ability for a mobile robo..

Crosstalk between poly(ADP-ribose) polymerase and sirtuin enzymes

Poly(ADP-ribose) polymerases (PARPs) are NAD(+) dependent enzymes that were identified as DNA repair proteins, however, today it seems clear that PARPs are responsible for a plethora of biological functions. Sirtuins (SIRTs) are NAD(+)-dependent deacetylase enzymes involved in the same biological processes as PARPs raising the question whether PARP and SIRT enzymes may interact with each other in physiological and pathophysiological conditions. Hereby we review the current understanding of the SIRT-PARP interplay in regard to the biochemical nature of the interaction (competition for the common NAD(+) substrate, mutual posttranslational modifications and direct transcriptional effects) and the physiological, or pathophysiological consequences of the interactions (metabolic events, oxidative stress response, genomic stability and ageing). Finally, we give an overview of the possibilities of pharmacological intervention to modulate PARP and SIRT enzymes either directly, or through modulating NAD(+) homeostasis