Nowadays technological systems are designed to meet the growing demands for safety and performance. This is emphasized especially for safety-critical applications such as aviation, aerospace or nuclear systems. Even small unnoticed and seemingly insignificant error or incorrect reaction to the error ca lead to catastrophic failure of the entire system. New control techniques and design approaches are developed to avoid fatal failures. These novel techniques and approaches are also able to adjust the required levels of performance including stability of the overall system in addition to ability to handle faults of the system. Such control systems are called fault tolerant control systems. Ability to achieving a certain level of system performance during occurence of fault in system components is sign of a degree of redundancy in the system. However reaching the level of performance may be limited by physical or economical means. Effective solution to this situation is to reduce the performance demands on system. Sometimes requirements have to be reduced to the stabilization only of the most important parts of the system. During occurence of the fault of one actuator the entire system and its performance depends on rest of actuators and their performance li, etc. and its performance depends on component limits. Therefore it is important to avoid excessive load of actuators and thus the risk of failure of the system. Often the remaining actuators are used to achieve state of the system that is considered to by safe instead to continue the task. The paper presents three different methods for control reconfiguration using virtual actuators that stabilize the system with the faulty actuator. Control algorithms as well as the conditi... ... middle of paper ... ...ther actuator is added in following simulations to replace actuator during failure so number of outputs of the system is equal to number of inputs. Extended nominal system and extended system with fault is used similarly as in previous part. In case of failure of the first actuator all state space variables are stabilized at desired values without permanent control deviation after start of the virtual actuator in time 70 seconds. Respons of the system can be seen on the following figure. Further simulations of virtual actuator with integral part are performed with extended system during failure of the third and fourth actuator. Goal of weak reconfiguration is accomplished simillarly as in previous part. Controlled variables achieve desired values hovever uncotrolled variables stabilize at non-zero values. Simulation results are summarized in following table.
A single point of failure refers to the failure of a component that can terminate
Disaster recovery is a useful feature of virtualization. Snapshots of your server can be taken regularly and as often as you prefer. Then, you can use any one of those snapshots to return your server to a particular configuration from a particular point in time. For example, before your network was infected by a virus.
Virginia Polytechnic Institute and State University will evaluate operational and technical risk areas. They will conduct UAV’s failure mode.
[3]. Zhang, N & Kezunovic, M. Verifying the Protection System Operation Using An Advanced Fault Analysis Tool Combined with the Event Tree Analysis. Northern American Power Symposium, NAPS 2004 Moscow, Idaho, (August 2004).
This is where means of a robotic device perform surgery– controlled by a human surgeon, which time and risk of complications are reduced. Virtual reality has been also being used for training purposes and, in the field of remote tele surgery in which the surgeon perform a surgery at a separate location to the patient. The main feature of this system is force feedback as the surgeon needs to be able to measure the amount of pressure to use when a delicate procedure is performed. However, there is an issue of time delay or latency which is a serious concern as any delay – can feel abnormal to the surgeon and interrupt the procedure. So there needs to be precise force feedback to prevent
Virtual Reality is a creation of a highly interactive computer based multimedia environment in which the user becomes a participant with the computer in a "virtually real" world. We are living in an era characterized by 3D virtual systems created by computer graphics. In the concept called Virtual Reality (VR), the virtual reality engineer is combining computer, video, image-processing, and sensor technologies so that a human can enter into and react with spaces generated by computer graphics.
Simulation system is some technology in virtual reality of immerse because the environment response with Head –Motion. This technology is very useful in virtual reality and work on computer modelling and interact with an artificial 3D dimensional visual . This system, help department of Air force, Navy, and Army using simulators with Virtual Reality to simulate the helicopter ,airplane, and s...
...to a very dangerous flight situations. Such issues make really unrealistic adopting such configuration for any civil aircraft without any specific countermeasure. Indeed, the rectification of these stability and control deficiencies and the provision of adequate flying qualities will require a very high authority augmentation system. Thus, a multiple-redundant command augmentation system must be implemented to make a neutral or slightly negatively permanent flying setting even only conceivable.
Today, thanks to the advancement in the field of electronics, most of the manually controlled systems are getting replaced with sophisticated electronic circuits with intelligent controlls. These circuits are capable of monitoring, analyzing and controlling the systems. In earlier days these electronic circuits were fabricated around discrete hardware components such as transistors, logic ICs etc that made the system bulky and costly. Also since the component count was more the failure rate was also more. But now due to the introduction of single chip microcontrollers, the hardware part was drastically reduced; so also the cost and size of the hardware has come down to a large extent. As a result almost all of the control circuits are designed over single chip microcontrollers.
Stefani, T. R. (2002). ‘Design of Feedback Control Systems’ 4th Edition. London: Oxford University Press.
Virtual reality is a new exploration in science and technology using advanced and complex mechanics. Virtual reality allows for users to go far beyond simply looking at a computer screen. Instead, the user puts on a special suit or gloves equipped with fiber-optic sensors. These fiber-optic sensors are able to interpret body positions. The user also wears special goggles that have video screens and audio attachments. This equipment allows for the user's complete immersion into a 3-D, computer generated, model of reality (Carr 37). The use of a two-way data transfer is what enables this interaction with an alternate reality to occur. Fiber-optic and electronic cables are attached to the virtual reality equipment in order to record the user's movements (Newquist 93). These cables then send this information, called motion data, to workstations which modifies the graphics in the model. The new information is then sent back to the users headset, displaying a graphic and audio world that is time with his or her movements. It is because of this cabling process that the action/reaction information is continually updated (93).
In this paper Internal Model Control (IMC) & Fuzzy Controller is used for inverse response of boiler drum level. The Internal Model Control (IMC) philosophy relies on the Internal Model Principle, which states that control can be achieved only if the control system encapsulates, either implicitly or explicitly, some representation of the process to be
A Robot must obey commands given to it, except where they conflict with the Zeroth or First Law
Preventive maintenance can be defined as an activity performed on a certain schedule which is intended to prevent breakdowns or deterioration. These activities can include regular inspection along with solving any discovered problems or situations and regularly scheduled parts changes. Preventive maintenance involves the scheduled adjustment, inspection, replacement of wearable parts, calibrations, basic cleaning and lubrication of equipment or other recommendation made by the equipment manufacturer. These activities can help increase the equipment functional life and help decrease facilities deterioration. No equipment should, No equipment should reach the breaking point [1].
The criticality of assets can be determined through historical repair data and the overall efficiency of the machines. The key performance indicators such as mean time between failure rates (MTBF) and mean time to repair (MTTR) will also help in the analysis. The criticality matrix is a suitable tool to evaluate, classify and prioritise an asset. This matrix also includes factors such as the cost of maintenance and costs related to lost production. After criticality analysis, the current maintenance strategy for top ranking assets is evaluated. The assets can be grouped together or individually evaluated. The criticality matrix results can be validated through different methods such as root cause analysis (RCA) or failure mode effect analysis (FMEA), which also provides qualitative analysis to assess reliability. These tools also help to determine the potential causes for failures or other factors which were not considered during criticality matrix