RC Robot Tank

For my intensive project, I am building an RC Robot Tank. Using a toy tread set, a motor and shield, and Arduino, I am going to build a base for the robot. Then, I will hook up an IR controller and sensor to control the robot.

Engineer

Andrew C.

Area of Interest

Engineering Physics

School

Los Gatos High School

Grade

Incoming Junior

Second Milestone

Second Milestone Video

For the second (and final) milestone of my RC Robot tank, I mounted everything on my chassis and got my robot moving. Most of the chassis was a simple assembly; I just used the Tamiya track set (the treads are a pain to assemble) and universal plane set. However, connecting the gear wheels to the motors was not a trivial task. I spent a few too many hours and made many, many attempts to create a 3D model to print as a sheath that fit around and connected the motors and the gears. Using TinkerCAD, I created a larger cylinder and created holes inside it to match the shape of the motor and the gear holes.

I mounted the motor shield to the chassis using screws and nuts. The motors were attached to the chassis using zip ties. Additionally, I transferred my IR sensor from bread board to circuit board, and it conveniently floated near the back of the robot. I wrapped the tread around my wheels and the robot moved, although it was unable to turn. I spent some time trying a variety of things, such as applying adhesive material and swapping out parts to try and minimize the friction that was preventing the motors from turning the robot. In the end, I settled for a gradual turn, as it was all my robot could take. Lastly, I attached the battery using zipties above the motors. It was heavy and it made the tank off-balanced, so I decided to use two large bolts in the back (which added a little aesthetic value) as a counterweight, and my project was finished.

First Milestone

First Milestone

For the first Milestone of my RC Robot tank, I got my motors running and I got the IR controller to control their motion. I first mounted the motor shield onto the Arduino. I soldered them together and added a bunch of pins. I then attached the 5 Volt Anker lead-acid battery, which will end up being my main source of power. I cut the USB cord and attached the pink and gray wires to my motor shield. I then attached my motors to the appropriate M1 and M2 ports using jumper wires. It took a few days to get the motors running; I tested many things but the problem ended up being a lack of I2C connections due to the test code (using the Adafruit Motor Shield library) not correctly addressing it.

Once the motors worked, I began to set up the IR Sensor. I first tried it without a breadboard, which didn’t work. I found a schematic for my IR sensor at https://arduino-info.wikispaces.com/file/view/IR-Receiver-AX-1838HS.pdf and assembled a breadboard accordingly. Using code from the IRRemote library, I got the hex codes for the buttons I wanted to use from my controller. To make my code get the remote controller to move the motors, I combined code from the Motor Shield Library and the IRRemote library. To correspond the button presses to a control on the motor, I used the case function, which ended up working better than using if statements, as I had tried before. After a couple days of modifying it, I tested my code and it worked!

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Starter Project

MintyBoost Video

Here is a picture of the completed MintyBoost circuit board.


Here is a schematic that shows the electrical connections within the MintyBoost.

For my starter project, I created a MintyBoost 5 Volt phone charger. To work, two AA batteries provide 3 Volts of energy, which is circulated through a circuit board and ultimately outputted into the USB port with 5 Volts. All instructions and details for the project can be found at https://learn.adafruit.com/minty-boost. I started by placing the five resistors into my circuit. Using a simple soldering job, they were implemented rather quickly. The resistors are used to apply resistance to the circuit, meaning they decrease the number of electrons flowing through the circuit in order to control it. I then soldered in the two ceramic capacitors. Ceramic capacitors, along with resistors, are non-polar, meaning the order they are positioned in the circuit does not matter. One of the ceramic capacitors is used to make sure the 5 Volt output is steady, and the other is used to make a voltage output that is precise as possible. I then inserted the schottky diode. This diode is polar so it is important that it is in the right direction; I actually put it in the wrong direction at first so I had to later desolder it and fix it. The diode is used to make sure the current only flows in one direction, to the USB port. I then placed the IC socket, which is really just used to protect the chip of the circuit. It was placed over one of the resistors and was connected to the circuit board in 8 places. I then inserted the power inductor. It is a cylindrical object that converts the power from low voltage to high voltage. I then placed the electrolytic capacitors in the circuit board. These are polar and their function is to smooth both the input and output voltages. I lastly inserted the boost converter chip, which was a central piece to the circuit and ended up being very valuable for testing voltages. A picture of the finished circuit board along with a schematic can be found above. At this point, it was time to test. Unfortunately, the readings did not match what I wanted. What started there was a two-day period of troubleshooting where I attempted to fix the problem in many different ways, continually failing to get a 5-Volt reading where I wanted to. The first problem I detected was a backwards diode. Unfortunately, when desoldering it, I clipped the wire and made it unable to use. I replaced it with a different schottky diode, which ultimately didn’t work as well. I ended up taking a diode from another MintyBoost kit, which worked. The next problem I detected was some connected solder between holes. I patched this up in a couple hours and still got no voltage reading. I then detected an issue with one of my capacitors using a multimeter and discovered that one side of the board had lost its metal ring, meaning I had to flip the capacitor to get conductivity through the board. When that didn’t work, I brought my project home and spent a couple hours using the schematic and a multimeter to determine where the circuit was not flowing. I discovered two areas (one of which ended up being nonexistent because the schematic I used had misnumbered the capacitors) where there was no flowing circuit. I connected the one interruption with jumper wires and finally got the reading I wanted. I soldered in the USB port and plugged my phone in and it worked! Through this process of building the MintyBoost along with the trial and error, I learned a whole lot. I learned about basic components of engineering, such as resistors, capacitors, and pretty much every part on my board. I learned about how to troubleshoot with a circuit board and how to utilize a schematic to test different voltage values. With this, I learned about volts, amps, and ohms and how they relate, and I learned fully how to use a digital multimeter. Lastly, I experienced challenge and failure, which are both a crucial part of the learning process in engineering. I am glad that I got to build the MintyBoost, and I learned so much about engineering as I built it and fixed it.

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