The shading system is the second major system of this self sustaining garden project. Its primary purpose is to maintain moisture in the garden. This is especially important because the water storage tank is dependent on rainwater for filling, even though it can be filled manually. So, if the system can somehow prevent moisture/humidity loss, there will be less stress on the watering system to have to constantly water the garden. The shading can also be used to prevent harmful sun rays from beating on the garden, even if the temperature is not too hot. Both of these conditions can prevent the garden from providing a bountiful harvest and healthy yield. 

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The major components of the shading systems are:

1. Shade Mounting

2. Shade Pivoting

3. Actual Shade

4. Solar Tracking

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Shade Mounting (circled in yellow above): The system is designed to mount to the garden box to provide shade directly over the garden. However, because the sun is not directly overhead, the shade needs to be mounted at a 45 degree angle. This should be able to block out most of the sun at all times of the day. To achieve the 45 degree angle for mounting, 3-D printed 45 degree blocks were made. This made it easy to mount the block to horizontal and vertical surfaces, and then the frame for the shade to the blocks. The frame held the shades, and each shading unit was held in place using bearings. In total, 4 of these 45 degree blocks were printed, so there could be one at each end of the frame.

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Shade Pivoting (circled in orange above): The pivoting motion of the shade is implemented using a servo motor. The housing is displayed in the image above. It can pivot the shade, because it is mounted so that the center of rotation for the shade and the motor are colinear. Then, using a rod and washers, the shades are all connected together. The washers are used to account for any error in mounting, so the pivoting action can happen smoothly. The pivoting of the shade allows for sunlight to either enter the garden, or prevent the sunlight from reaching the garden. This gives the user the ability to control the exact amount of sunlight they want the garden to have. 

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Actual Shade (circled in green above): This unit holds the shading for the garden. What is seen above, is a series of brackets that hold rods where the shade is mounted to. The brackets were all 3-D printed, and were then fit into 3/8" ID bearings. In total, there will be 6 of these units. This allows for shade to hang over the garden on each side, to ensure the shade is always directly over the garden when needed. In total, 12 brackets would need to be printed, 12 bearings would be needed, and 12 1' long pieces of 3/16" rod were needed for assembly.

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Solar Tracking (not shown in the image above): Using 2 CDS cells mounted to point 45 degrees apart from each other was used to track the sunlight. When one CDS cell starts to read a higher light, the system knows that the shade needs to be pointing in a certain position based on the outside temperature. When the CDS cells are equal, or close to, the system knows the sun is directly overhead. So, the sunlight controls the system through the use of the solar tracking CDS cells. However, in the final assembly of the system, the CDS cells do not read well, and makes the servo motor track only to the high and low ends. To fix this, a potentiometer was used to simulate the movement of the sun.

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Not shown in the diagram above is the thermistor. This unit monitors the temperature of the garden to help the system know when to shade or follow. When the temperature is not warm enough, the shade follows the sun to allow sun into the garden. However, if it is too hot, the shade will pivot the other direction to block the sun.