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As part of the case study of the satellite tracking system, the programme develops a theoretical model that can be used to predict the behaviour of the system and how it can be controlled.
Metadata describing this Open University video programme
Module code and title: T391, Control engineering
Item code: T391; 04
First transmission date: 31-05-1978
Published: 1978
Rights Statement:
Restrictions on use:
Duration: 00:24:33
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Producer: Edward Smith
Contributors: Dick Fendrich; John Monk
Publisher: BBC Open University
Keyword(s): Control engineering; Control systems; Transfer function analyser
Footage description: John Monk introduces the programme. Over shots of a working model of the satellite tracking system and a block diagram of that system, Monk points out its basic components. He connects up the working model which proves unstable in both closed and open loop modes. Dick Fendrich performs an experiment with a schematic working model of the tracking antenna in order to obtain measurements for the amplitude ratio and phase shift. These are displayed on a transfer function analyser. John Monk plots the results from this experience on a Bode graph. The resulting curve for the antenna system closely resembles a second order model. Dick Fendrich models the antenna motor with another, smaller motor of the same type in the studio. He subjects this motor to a step change in input voltage and records the output on a pen recorder graph. The resulting curve resembles the step response of a first order model. Fendrich captions the differential equation which describes a first order model like this. John Monk begins to work from the differential equation obtained above towards a Bode diagram so that the model of the antenna structure can be combined with that for the motor. As a first step he works out a transfer function model of an integrator and a transfer function of a first order lag. Monk writes the mathematics on a board as he talks. Continuing to write and draw on a board, John Monk works out the amplitude ratio and phase shift for the motor. In order to plot the amplitude ratio for the motor on a Bode graph, John Monk works out the amplitude ratio in decibels. Having calculated the amplitude ratio in decibels, Monk plots the resulting curve on the Bode graph, he also has plotted on this graph the curve for an integrator. Monk adds the two curves together and draws an approximation of the result. Finally Monk combines the curve for the motor with that of the antenna on a Bode diagram. He then sums up the programme.
Master spool number: 6HT/72736
Production number: 00525_5320
Videofinder number: 1098
Available to public: no