Aim: Design and build sun ray bender device that will reflect light into chosen locations throughout the day
Objectives:
- Design mechanical frame, gimbal and gearing including loading considerations from the mirror
- Draw up architecture to interface the R102010328 Arduino Microcontroller Board with the sensors, motor drivers and peripheral communications
- Build the prototype board to integrate above (2) with mechanical assembly to complete the system (mechanical + electronics)
- Test the system for multiple days to allow for the modifications and improvements
- Write blogs on above steps.
Motivation:
My house has north/north-west facing garden. Unfortunately, being on the northern hemisphere with significant latitude, the garden is in shadow for significant part of the year (more than 5 months). In the months leading up to winter as well as following the winter, we are unable to use our conservatory and backyard due to cold conditions. I have noticed that if we can get sunshine into our conservatory, it can start heating up quite quickly (thanks to greenhouse effect!) and therefore, we could extend our use of those parts of the house for more months than we currently do. Also, this using the sun to heat up part of our house will be eco-friently! The added benefit will be that we will not need to turn on our kitchen lights during dawn and dusk because the light will be shining directly into the conservatory adjacent to our kitchen, partitioned by glass doors. This challenge is a perfect opportunity to make improvements in my lifestyle and hopefully inspire others to follow the eco-friendly routes to lifestyle.
(note: sun trajectory shown in the pitcure only for illustration purpose and are not to scale.)
In the summer months, the sun traces trajectory much above the shown yellow trajectory. In fact, it flips on this side of the house such that the conservatory gets sun throughout the day. However, as winter months approache, the sun gets lower and lower towards the horizon leaving much the back of my house in permanent shadow (trajectory shown in orange and red).
The photo below is from mid-october around 11am.
The photo below is on the same day as above but around 3pm.
Project plan:
In this project, I will be using mirror mounted on a gimbal stand, to reflect the sun rays into my house and garden. The gimbal will be motorised and R102010328 Arduino Microcontroller Board (SEEED STUDIO XIAO) will be used to host the main software that will help keep the focus onto several chosen spots. I will use filtered accelerometer signal to work out attitude (azimuth and elevation angles) to use for the feedback. It is understood that it will not be good enough to calculate angles and therefore, it will be researched to find practical ways to determine mirror angles in 3-axis system. It may turn out that I will need a gyroscope as well to use the rates to fuse with the accelerometer signals for this purpose. However, simpler and effective option would be preferred. On board RTC will be used to track the sun position accurately to be able to reflect the sun appropriately to chosen spot. Throughout the day, the reflector will be moved regularly to reflect on different spots so that only one spot doesn’t heat up too much causing discolouration, spot heating, and any unintentional effects. Alongside this, due to Earth’s orbit around the sun and the Earth’s tilt, the sun trajectory on the sky will gradually change throughout the year. This will need to be accounted for in the algorithm such that the mirror reflects the sun accurately. In the months of the summer, it will be desired to point the mirror into the upstairs bedrooms at the back as they are getting colder due to convection caused by heating on the front of the house. So, overall, I will not only be reflecting the sun into my house but because I will be adjusting the mirror position continuously, i.e., bend the rays to let them into my desired place, hence I have chosen the name ‘sun ray bender’ rather than ‘sun ray reflector’.
Materials:
For this project, I will obviously need a mirror to reflect/bend the sun rays, and motors to move the mirror into its desired position. Motors will need a driver to drive them with power that is regulated according to the implemented logic from the microcontroller. Also, some sensors will be needed to know the current attitude and some additional info (such as humidity and temperature to estimate if it might be sunny or rainy). Finally, structure will be needed to hold the mirror. So, reiterating the above into list form (not an exhaustive list):
- Mirror
- Geared motors (DC, BLDC or Stepper, any will work)
- Motor driver
- Power supply (likely 12V)
- 12V to 5V DC-DC regulator
- Brackets/gimbal and tripod or pole to mount motors and mirror
- Microcontroller (Seeed Studio XIAO - R102010328 Arduino Microcontroller Board)
- Temperature and humidity sensor (Grove - Temperature&Humidity Sensor(DHT20))
- IMU - accelerometer (Grove - 3-Axis Digital Accelerometer)
- Wires, solders, perf board, connectors, etc.
Let me show you a picture with some of those things that I have collected and items from the kit that I have received, thanks to element14 challenge organisers! 
On the top left there are two geared motors that I have salvaged from a broken office printer. I have opened one motor's housing to show the internal parts. Below the motors there is DRI0017 that I had from previous challenge - to drive these motors, perfect combination! 
An then there is Seeeduino XIAO in the middle with humidity sensor and accelerometers in their packaging!
Excited to build the project! I'm all geared 
up so, let's get craking! 
