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Topic: Arduino Rover Columbus - communication and energy problems (Read 546 times) previous topic - next topic

ProjectColumbus

Jun 18, 2019, 08:15 pm Last Edit: Jun 18, 2019, 08:16 pm by ProjectColumbus
Hello,
Let's start with an introduction of my project. I want to build a Rover, like the Mars Rovers, but it will stay here on Earth. It will be displayed at our schools project week. It will drive around a rocky place in the schools backyard, and it will be solar-powered. It's controller will be a Nodemcu (ESP8266 0.9). The Rover will be named "Columbus".

Now, I know how Columbus will look and what the prototype needs to do, but I have some problems. They are listed below, and any help is appreciated!

1.) The communication

This part is not build nor programmed yet, I need help with the communication between Columbus and the PC.
The Rover needs to communicate wireless and transmit data from an DTH11 - sensor as well as from an ultrasonic sensor (the model is at school, so I don't know the number).
It would be very nice if the Rover could send pictures in low resolution as well, for navigational purposes and for science. That, however, is not necessarily needed for its display.
I already googled, and there seem to be ways to communicate with Columbus using 433 MHz, 868 Mhz and normal WiFi (the ESP has built in WiFi access.) The problem here is that normal Wi-Fi has the highest data rate and could easily transfer photos, but it's range is too short. For 433 and 868 Mhz, I could not find the range, but I know that the data rate is in between 1 and 20 Kbits (433 MHz) and 300 Kbits (868 Mhz). I could wait for the photo to arrive, but I don't know how to build a setup that transfers data (and maybe photos) between Columbus and the computer, and also, I don't know how I can make the ESP handle the steering commands correctly and what communication module I should use.

2.) Energy supply

The rover will be solar powered, like I said, using 4 solar modules producing 5V and around 200mA (500mA max.). For the night or for cloudy days, there will be a battery with 5000 mAH and a 5V output. I know that the ESP has a consumption of about 200mA in normal mode and about 400mA while using Wi-Fi or being flashed.
The problem here is: I don't know what camera to take (see below), how much the DTH11 and the ultrasonic sensor consumes and, the biggest problem, how to make the 5V to power the two 12V motors we use.

3.) Camera and position

For navigation, Columbus should get a camera to take photos of obstacles. The photo resolution won't need to be that high, just enough to identify hazards. I know that it can take up to 8 minutes to send a photo using the 433/686 MHz communication, and it is okay for us to wait that long. The point is that it needs to have a low energy consumption, and I could not find a camera for the ESP/Arduino yet. If someone knows a camera I could use, that would be very nice! Also, I don't know how the ESP should handle photos as it doesn't have a flash drive. My idea was that Columbus takes a photo at command and sends it immediately to the PC.
For position, it would be nice to use a GPS module. That is, however, not needed for now as the test site will be small. I still want to know how to use a GPS module for later development stages.

Those are the main problems I currently have with Columbus. If you can solve them (or only two or one of them), that would be nice and greatly appreciated!

If you want to know more technical details about the rover, feel free to contact me.

Have a nice day!

PaulS

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It's controller will be a Nodemcu (ESP8266 0.9).
Why have you chosen that particular controller? WiFi is not particularly well suited for speedy control.

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transmit data from an DTH11 - sensor
Is that anything like a DHT11 sensor?

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It would be very nice if the Rover could send pictures in low resolution as well
How long do you have to do this project? Are you referring to single pictures or video?

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but it's range is too short.
What range do you think you need?

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For 433 and 868 Mhz, I could not find the range
Depends on what kind of radio you are thinking of using, and what kind of antenna you plan to use.

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and, the biggest problem, how to make the 5V to power the two 12V motors we use.
How much current do your motors need? I have my doubts that the 500mA, even if it was at 12V, would be enough to make the motors do more than snicker at you.

The art of getting good answers lies in asking good questions.

ProjectColumbus

I originally planned on making the data and photo transfer using WiFi because of its higher data rates. I also planned on connecting it to a normal Arduino.

I meant the DHT11, I just noticed I made a typo there :/

The project is for two weeks from now on, but I want to continue it in my spare time since summer vacation starts soon. For now, single pictures are good, I need them for navigation. If there is a way of making a video or maybe even a stream, I might add it in later.

For the school, only about 50 meters. For the model I will build after that, a few kilometers would be nice. 1km is okay, better are 3 or maybe even 5 kilometers.

I thought of a helix, Yagi or bi-quad antenna. They have an angle of 15 to 45 degrees and get good ranges, but the rover does not.

The solar modules produce 500 mA each, meaning that I have 1000 mA. Those will charge up a battery that gives a 2000 mA output. The motors need a current of 800 mA each, both need 1600 mA.
I have smaller motors with lower speed, they only take 1,5 V (again, how do I lower 3 V to 1,5 V) and around 400 MA (not sure though).

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