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Advanced Automation function
In addition to executing work cycle programs, an automated system may be capable of executing advanced functions that are specific to a particular work unit. In general, the functions are concerned with enhancing the safety and performance of the equipment. Advanced automation functions include the following
(1) Safety monitoring,
(2) Maintenance and repair diagnostics, and
(3) Error detection and recovery.
automation functions are made possible by special subroutines included in the program of instructions. In some cases, the functions provide information only and do not involve any physical actions by the control systems, for example reporting a list of preventive maintenance tasks that should be accomplished. Any actions taken on the basis of this report are decided by the human operations and managers of the systems and not by the system itself. In other cases, the program of instructions must be physically executed by the control system using available actuators. A simple example of this case is a safety monitoring system that sounds an alarm when a human worker gets dangerously close to the automated equipment.
One of the significant reasons for automating a manufacturing operation is to remove workers from a hazardous working environment. An automated system is often installed to perform a potentially dangerous operation that would otherwise be accomplished manfully by human workers. However, even in automated systems, workers are still needed to service the system at periodic intervals if not full-time, accordingly, it is important that the automated system be designed to operate safety when workers are in attendance. In addition, it is essential that the automated system carry out it is process in a way that is not self-destructive. Thus, there are two reasons for providing an automated system with a safety monitoring capability:
(1) to product human workers in the vicinity of the system and
(2) to product the equipment associated with the system.
Safety monitoring means more than the conventional safety measures taken in a manufacturing operation, such a productive shield around the operation or the kinds of manual devices that might be utilized by human workers such as emergency stop buttons. Safety monitoring in an automated system involves the uses of sensors to track the systems operation and identify conditions and events that are unsafe or potentially unsafe. The safety monitoring system is programmed to respond to unsafe conditions in some appropriate way
.Possible responses to various hazards might include one more of the following:
1. completely stopping the automated system,
2. sounding an alarm
3. reducing the operating speed of the process,
4. Tacking corrective actions to recover from the safety violation.
This last response is the most sophisticated and is suggestive of an intelligent machine performing some advanced strategy. This kind of response is applicable to a variety of possible mishaps, not necessarily confined to safety issues, and is called error detection and recovery
Sensors for safety monitoring range from very simple devices to highly sophisticated systems. The following list suggests some of the possible sensors and their applications for safety monitoring:
· Limit switches to detect proper positioning of a part in a work holding devices so that the processing cycle can begin.
· Photoelectric sensors trigged by the interruption of a light beam; this could be used to indicate that a part is in the proper positions or to detect the pressure of a human intruder in the work cell.
· Temperature sensors to indicate the metal work part is hot enough to proceed with hot forging operations. if the work part is not sufficiently heated, then the metals ductility might be too low, and the forging dies might be damaged during the operations.
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