Testing Servo-System Components without Closing the Loop

Some servo control devices are more conveniently tested outside the systems they control. This paper presents a survey of some of the most promising methods of testing such devices, and concludes that open loop testing by reproducing an input function recorded on magnetic tape and observing response can reliably separate acceptable and faulty units. Equipment designed to perform the test is economical and fully automatic. In the space age, when servo-systems operate in exotic environments and control large amounts of power, it is a formidable job to simulate the operating conditions of the complete system for tests of each component. It is desirable and convenient to test these components as isolated "black boxes", supplying only the power and environmental conditions required for the item under test.