Machine interface level

This section illustrates some of the more global influences at the organizational level which create the preconditions for error. Inadequate policies in areas such as the design of the human-machine interface, procedures, training, and the organization of work will also have contributed implicitly to many of the other human errors considered in this chapter. 

Note 2 The lighting level in the central control room can be arranged to be wholly or partly adjustable so as to minimise glare and eyestrain whilst operating visual display units (VDU) or man-machine interfaces (MMl). 

Instrumented human-machine interface techniques These techniques are used to passively and unobtrusively collect objective data on task performance and the procedures by building the data collection into the interface itself. These techniques are used to record the timing, sequences, and frequencies of explicit actions. These can, for example, model navigation through a website using search and hyperlink actions or the low-level actions that are done to accomplish the navigation such as keystrokes, button pushes, and mouse movements. 

The recorded signals have to be processed functionally and archived in defined time frames for later analysis. Signals with the highest security level will be integrated in an additional system. Operating relevant values can be visualized in the human machine interface display. 

CTA seeks to promote appropriate job and task design, suitable physical environments and workspaces, human-machine interfaces and the appropriate selection, training and motivation of the humans involved. At the detailed level CTA examines how the design of human-computer interactions can foster the efficient transmission of information between the human and machine, in a form suitable for the task demands and human physical and cognitive capabilities. 

The design of the SIS shall take into account human capabilities and limitations and be suitable for the task assigned to operators and maintenance staff. The design of all human-machine interfaces shall follow good human factors practice and shall accommodate the likely level of training or awareness that operators should receive. 

Master Terminal Units (MTU) collect sensor data from several RTUs and provides the data to other high-level stations (e.g., hmnan machine interfaces (HMI) to give human users a system overview). MTUs also send actuator commands to the appropriate RTU which executes them. 

Level 2, for the control of abnormal operation and the detection of failures, is to be reinforced (for example by more systematic use of limitation systems, independent from control systems), with feedback of operating experience, an improved human-machine interface and extended diagnostic systems. This covers instrumentation and control capabilities over the necessary ranges and the use of digital technology of proven reliability. 

Outline of design and engineering process. D and E, design and engineering FAT, factory acceptance test HMI, human—machine interface MOC, Management of change SIL, safety integrity level. 

Centralized control approach. DCS, distributed control system ESD, emergency shutdown system HMJ, human—machine interface MIS, management information system PU, pro cessing unit SIL, safety integrity level SIS, safety instrumentation system. 

Generally, the use of BBNs to model the impact of MOFs aims to explicitly model their multilevel and hierarchical influences on the HEPs, as discussed in Li et al. (2012), Cai et al. (2013) and Martins Maturana (2013). Many of the influencing factors typically considered by HRA methods can be thought of having direct influence on the HEP, e.g. the quality of the human machine interface and the time available for the personnel to carry out their tasks. In contrast, many of those referred to as MOFs have indirect effects for example the management s commitment to safety influences the quality of personnel training, which then directly influences the HEP. The BBN ability to represent multi-level relations helps to model these types of hierarchies. Figure 1 shows an example of the hierarchical influences. 

Design properties. Covering aspects related to redundancy, diversity and functionality of the specific equipment (see example in Table 3). Special considerations. Aspects related to previous experience with/maturity of the equipment, complexity of the design, possible weak points in the design, etc. Human machine interface. Aspects related to accessibility to and maintainability of the equipment, including planned level of human interaction in... 

Since the late 1990s, the European Commission has elaborated a recommendation for in-car information systems, which was issued in 2007 as "Commission Recommendation of 22 December 2006 on safe and efficient in-vehicle information and communication systems, see [13], This recommendation is an update of the European Statement of Principles on Human Machine Interface (1999) and describes on a generic level how the service interaction with the driver shall be implemented it suggests driver training and gives advice regarding user as well as installation manuals issues. The EU recommendation was a valuable source for many of the COOPERS HMI requirements. 

Up until now, only fully automated safety functions have been taken into account, but in many critical functions, man intervenes directly (PLC level). This raises the problem of human rehabihty and incorporating the operator s action into the reliability chain of the safety function. Indeed, from a set of enviromnental parameters or human observable actions, the operator is often able to identify a dangerous situation and activate a mitigation action, via a mechanical or an electronic and/or programmable feedback cham. This area of reliabihty of the human-machine interface is not addressed in this document. 

The core of the system validation process is done on a simnlation platform faithfully reproducing the system architecture. It recreates the safety controller environment and the human-machine interfaces ensuring operation and supervision of the system. The software for each LHC site has been fully tested on this platform by activating inputs and verifying ontputs at the electrical level. This form of verification and validation optimizes the final test eampaigns conducted in the 27 kilometer tunnel of the LHC ring, the serviee zones, and the experimental adjacent zones. 

Predisposing Factors Level 1 - The Person - Machine Interface... 

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