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# Developing the function structure of the solar tracker

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Now that you have understood some of the issues in the solar tracker problem, you are going to develop its function structure

## Develop a function structure

You can do this in two steps:
1. Identify the main functions of the solar tracker apparatus. Remember that functions are usually described using verbs such as support, rotate, detect, convert, etc.
2. Draw a function structure that shows the interaction of these functions with each other (a function structure is often set out as a flow chart).

## Model solution

You’re not expected to get a perfect answer to this but do compare your function structure with the one in the model solution.

## Function structure exercise: model solution

A proposed function structure for the solar tracker is shown in the diagram below. In this diagram, the functions are given numbers such as F1, F2, etc so that they can be referred to in the following text.

## Function F1

First of all, a function F1 is needed to determine the sun’s position in the sky at any point in time. The output of F1 is one or more signals that determine the sun’s position in the sky. At this stage it isn’t known and you don’t want to commit yourself to any particular method of determining the sun’s position. All that is needed to be specified at this point is that F1 must somehow tell us about the current location of the sun.

## Function F2

The output from F1 is fed into another function F2 that conditions the signal so that it can be applied to function, F3. Function F2, may or may not be needed depending on the nature of the solutions that are chosen for F1 and F3. The term signal conditioning is used to describe any process that changes some or more parameters of a signal, such as amplifying, clipping, or inverting it.

## Function F3

Function F3 may be required to provide power to drive the actuators that rotate the panel. As with F2, this function may not be needed if the signal from F1 or F2 is suitable for direct application to functions F4 and F5 that move the panel. We can’t determine if this function is needed until we have chosen solutions for F1, F2, F4, and F5.

## Functions F4 and F5

Functions F4 and F5 are needed to move the panel in two different directions. F4 moves the panel to track the sun’s position as it moves from east to west, and F5 to make the panel track the sun’s motion from south to north.

## Function F6

Finally, function F6 is needed to firmly support the panel and allow it to rotate in two different directions.

As you can see, the functions have been described in the most abstract sense and avoiding reference to any particular solution method for any the functions. This will allow us to explore all potential solutions and develop many possible concepts for the operation of the apparatus.