Safety control comes in two ways: self-conrmation interlock and mutual-conrmation interlock. The mutualconrmation interlock is a control pattern that permits the control output to be produced for one of two controlled
objects as long as the control output is not produced for the other controlled object. The function required of the interlocking system includes this mutual-conrmation interlock. The mutual-conrmation interlock is easy to congure when all of the controlled objects are centralizedly processed. Since the objects to be controlled or checked vary in conditions from station to station, however, it is necessary to design the interlocking function for the individual stations.
The design of interlocking devices depends on the layout of station signaling equipment, or switches, track circuits and signals. The authors have studied the possibility of preparing functional elements as units for signals and connecting the functional units according to eld wiring to perform the required function(1), (2). To ensure the autonomy of the units against failure, it is necessary that they should individually have fail-safe error characteristics. To achieve the fail-safe error characteristics by using the asymmetric error characteristics, it is only necessary to realize the unit function by monotonic logic functions. The mutual-conrmation interlock, however, includes NOT operations and cannot be realized by the monotonic logic function.
The authors have studied an interlocking system by diving it into safety-related parts and non-safety-related parts and accomplishing it as a hybrid conguration of
the safety-related parts and non-safety-related parts. In the interlocking system, the safety-related parts only judge whether or not action should be initiated, and the non-safety-related parts are entrusted to initiate action. The control requirements of signal aspects and switches are assigned to the non-safety-related parts, and the safety-related parts perform safety conrmation processing to judge whether or not the requirements are acceptable. This separation and the introduction of duality conversion described later help to achieve the mutual-conrmation interlock in the interlocking system by the monotonic logic functions.
Chapter 2 shows safety control characteristics for the functions required of the entire line. The functions of the safety-related parts are classied into self-conrmation in-terlock and mutual-conrmation interlock. Chapter 3 claries the preconditions for the requirements of the interlocking functions and demonstrates the possibility of realizing the mutual-conrmation interlocking function by monotonic logic through introduction of duality transformation.
可以只翻译一半呵呵 确实有点多
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