Top View of the Base
Bottom View of the Base
Finished Sun Pointer
For the 60th Birthday of my host-dad, I decided to build something from scratch as a present.
I also wanted to apply my knowledge from last semester and I came up to create a 'Sun Pointer', an arrow moved by two stepper motors.
The motors are controlled by a microcontroller, so that the arrow always points towards the sun.
During the day, even when cloudy, you would be able to tell the exact position of the sun.
This applies to the night and indoors as well.
In my class "Renewable Energy Technology" I learned about an algorithm that calculates the position of the sun, described by the azimuth from north and altitude from the horizon.
Both Values are returned in degrees.
The algorithm requires the current time and the latitude and longitude.
The time is traced using a DS3231 IC.
Since the latitude and longitude do not change when in use, they can be hard-coded into the firmware or by the user once.
During startup, the Arrow needs to be pointing north towards the horizon when the azimuth and altitude are applied.
In operation, the microcontroller recalculates the azimuth and altitude of the sun every minute and adjusts the arrow via the stepper motors if necessary.
Below, you can see the first azimuth test performed. This proofs that the implemented algorithm adjust the stepper motor as expected.
Timelapse of the Azimuth Motor Test Following the Sun,
Notice how the shadow stays under the 'pointer' throughout the day.
I designed the PCB layout and etched it at home. The PCB is placed inside an acrylic enclosure, the 'base' without the arrow.
The top motor that is rotating with the azimuth needs to be connected to the microcontroller.
During multiple days and rotations, the connecting cable would tangle with the azimuth-axle.
Thus, once the azimuth completes a 360° turn, the azimuth turns back around to avoid the cable getting tangled.
The project worked out very well and I enjoyed looking at the sun pointer throughout the day more than I expected.
I will create a second sun pointer for myself, however the enclosure and arrow took way too much work to complete.
For the next iteration, I will buy a 3D printer, so that it is easier to reproduce the sun pointer.
Top View of the Base
Bottom View of the Base
Side View of the Base
© Michael Smirnov 2020
m_smirnov@me.com