Proportional control

About: Proportional control is a research topic. Over the lifetime, 3756 publications have been published within this topic receiving 49050 citations.

Fast Worm Containment Using Feedback Control

Abstract: In a computer network, network security is accomplished using elements such as firewalls, hosts, servers, routers, intrusion detection systems, and honey pots. These network elements need to know the nature or anomaly of the worm a priori to detect the attack. Modern viruses such as Code Red, Sapphire, and Nimda spread quickly. Therefore, it is impractical if not impossible for human mediated responses to these fast-spreading viruses. Several epidemic studies show that automatic tracking of resource usage and control provides an effective method to contain the damage. In this paper, we propose a novel security architecture based on the control system theory. In particular, we describe a state-space feedback control model that detects and control the spread of these viruses or worms by measuring the velocity of the number of new connections an infected host makes. The mechanism's objective is to slow down a worm's spreading velocity by controlling (delaying) the number of new connections made by an infected host. A proportional and integral (PI) controller is used for a continuous control of the feedback loop. The approach proposed here has been verified in a laboratory setup, and we were able to contain the infection so that it affected less than 5 percent of the hosts. We have also implemented a protocol for exchanging control-specific information between the network elements. The results from the simulation and experimental setup combined with the sensitivity analysis demonstrate the applicability and accuracy of the approach.

Fault-tolerant cooperative control for multiple UAVs based on sliding mode techniques

Abstract: This paper proposes a fault-tolerant cooperative control (FTCC) design approach for multiple unmanned aerial vehicles (UAVs), where the outer-loop control and the inner-loop fault accommodation are explicitly considered. The reference signals for the inner-loop of the follower UAV can be directly produced by resorting to a proportional control. In the presence of actuator faults, the estimation of the fault information can be completed within finite time. Moreover, the control of the inner-loop is reconfigured based on the fault information adaptation and sliding mode techniques, such that the deleterious effects due to failed actuators can be compensated within finite time. Simulations of UAV cooperative flight are conducted to illustrate the effectiveness of this FTCC scheme.

Attitude control in walking hexapod robots: an analogic spatio-temporal approach

Abstract: In this paper, the control system of a biologically inspired walking robot is presented. An analog distributed system acts as Central Pattern Generator for the locomotion control, while the attitude control is performed by using a proportional integrative controller for each leg. The inclusion of a saturation block in the attitude control scheme allows to take into account the joint limits, leading to the formulation of a cellular non-linear network (CNN) based attitude controller. Thus, the whole control system can be structured as an analog control system realized by CNNs generating the locomotion pattern as a function of the sensorial stimuli from the environment. Both the network design and circuit realization are presented in this paper. Some experimental results obtained with the 18 degrees-of-freedom walking robot prototype are also reported. Moreover, some interesting experiments showing the robot capabilities to escape from unforeseen situations, in which overloading causes the saturation of a joint motor, are emphasized as an emerging result due to the action on both the locomotion control and the attitude control. Copyright © 2002 John Wiley & Sons, Ltd.

A Microprocessor-Based Electrode Movement Controller for Spot Weld Quality Assurance

Abstract: Quality assurance has been of a great concern in the process of resistance spot welding, since considerable variation in the weld quality often arises even when the machine variables are held constant. In this paper a new microprocessor-based control method is developed to obtain uniform weld quality regardless of the changing welding environments. The control system utilizes a proportional (P) control algorithm, incorporating with the electrode movement as a feedback variable. The controller generates the welding control current so as to track a desired trace of the electrode movement (reference electrode movement curve) throughout weld cycle. A series of experiments was performed to evaluate the performance of this control method. The results show that, as a result of the electrode movement tracking, weld strengths of all the weldments approach to a desired strength level.