System Control

 

Since the systems are designed to achieve specific objectives, ensuring the achievement of the objectives through system control, becomes the integral part of the system design. The control calls for, in the first place, a measurement of the output in some terms. The device that measures the output is called a sensor. The next step is to set the standard or norm of the output as an index of the system performance. The sensor measures the output the compares it with the standard.  If the measured output compares well with the standard, the system provides a feedback to continue the operations.

 

If the measured output does not compare well with the standard, then a feedback is provided to the system to stop the operations.  The process of comparison of a measured output with the standard is done by a unit called as comparison unit.

 

The mechanism, which provides a signal to the system, about the quality of performance, favorable or adverse, is called a feedback mechanism.

 

Many times, the system may not have an appropriate mechanism to act on the signal which it receives. It is, therefore, necessary to provide an in-built mechanism which will decide, based on the feedback, to stop, regulate or continue the system operations. Such as mechanism is called a corrective unit and it is responsible for ensuring the system performance. The corrective unit, in its performance, will act on inputs and processes to bring the system under control.

 

The process of measuring the output, comparing with the standard, sending the signal to the corrective unit and the corrective unit action upon it, is called a control. Any breakdown in this path will affect the system performance adversely.

 

A system set for a specific objective, devoid of any control, will perform in a disorderly manner and can disturb the system equilibrium.  The role of a control is to regulate the system operations and performance, and keep it in an equilibrium condition. The control, therefore, is the heart and brain of the system.

 

The control could either be internal or external to the system.  For example, in an air conditioning system, switching on and off the compressor is automatic and hence it is an internal control. In the roads and traffic system, the traffic policeman acts as a control system, which is external to the traffic system?  Most of the modern systems have in-built automatic control systems.

 

The information system can be understood in terms of system concepts.  The information system receives the inputs of the data and the instructions (a set of the Computer Programmes), processes the data according to the give instruction, and gives the output of the processed results.

 

The information systems are designed in a particular environment of business, industry and management. When the environmental factors or the inputs change, the system process is under a stress.  Stress beyond a limit affects the other system elements which in turn affects the achievements of the goal.  A system may have the ability to manage the stress and still be in a condition to achieve the desired goal. Unmanageable stress leads to a system failure.

 

The concept of control is based on the condition of a feedback. If the feedback is positive, i.e., the measure of the output compares favorably with the standard or norm, the control will keep the system operating in the same condition. However, if the feedback is negative, i.e., the measure of the output is unfavorable when compared to the standard or norm, the control will act on the input or process to bring back the system to the state of equilibrium.