lightwalker-devlog-blog

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Creating the Solar charging system

As of Sunday 24th November, the pieces for the system have still not arrived in the mail. They should be here by Monday, so I will update this post with the build log then.

EDIT:

Okay! We finally have the charging system completed.

This follows the last post’s diagram. The arduino board is plugged into the green chip, and it provides a 5V supply to the board.

Unfortunately, the DC adapter for the solar panel has not yet arrived, but when it does, the battery can be charged via the TP4056 (blue chip).

Here is the output for the solar panel.

This is the TP4056. It is responsible for charging the battery. The input is labelled on the pcb, and if you look closely you can see a diode for reverse voltage protection for when the solar panel is added. The chip also has a mini usb port, so the board can be charged without a solar panel as well - this won’t be used in the project, though.

This is a 3.7V to 5V step up chip. Since the lithium battery outputs 3.7V, the voltage needs to be increased so that it can power the metro board.

Here is a link to a video of the metro being powered via the board. The metro is running a simple blinking LED script.

This will need to be stored in a container for the final project, to make it look a lot nicer. The board looks very big, but is roughly the same size as the solar panel, so it will not be a problem. The size also helps dissipate heat, as the charging module and step up module will get hot, and keeping that heat away from the battery is important.

The next stage of the project will be implementing the light seeking and moving of the device. To avoid feature creep, the light seeking element of the project may need to be cut, and the device may have to wander at random until it finds an area of suitable charging potential.

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Prototyping

Unfortunately, not all of the pieces I need to build a prototype have arrived in the mail. As such, this post will be entirely diagram based until I can build the prototype.

The post is going to focus on the solar power for the device, as it is required for the device to be autonomous. The device will be mainly powered using a lithium battery, but the battery will be charged using a solar panel. This is to avoid power outages whilst the device is running.

I will be using this guide to make the solar array, diagram shown here:

However, this guide utilizes a smaller solar cell than is required for the arduino - instead, I will be using this panel from sparkfun, as it has a higher wattage, which is required by the arduino.

As for the light sensing, I am planning on using miniature solar cells from sparkfun to detect light around the device. Using a small ring of them, I can move the device in the direction that the panel with the highest output is facing.

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First Post and explanation of project

The project I am creating is an autonomous robot that is powered by a solar panel; its sole function is to find areas of high sunlight to move to and charge itself. This is a focus on the artificial life theme. I would liken the idea to a plant - instead of growing to areas of sunlight, the robot would instead be required to move there to ‘survive’.

This idea intrigues me, as once it is complete, it would no longer require input or assistance from an outside influence to function. It would act entirely on its own, and it would be interesting to see how tweaks to its code or physical layout would change how long it survives for - almost like evolution.

The one thing I would not change about the project is the autonomy aspect - the robot could find power in other ways, such as wind power, or returning to a charging station when low on power, but it must not lose the inability to be acted upon by an outside party.

An audience to the robot would be different than most others, as usually input is required. In this case, the audience is purely spectating what the robot does, similar to the entertainment one might get from watching fish in a fishbowl.

I believe this to be well within scope; the physical aspects of the device are rather simple, and is much more about how the code interacts with the real world. Since we have covered servos in labs, and solar power is relatively simple (I plan to use and adapt a guide for solar power on arduinos from here) I believe the project can be completed before January.

I first got the idea for this device from this project page. It is an arduino weather station. I thought that making a device that finds its own power and takes readings as well would be extremely interesting, but decided to focus only on the power aspect, as otherwise the project would be too large.