Seeing my robotic arm work as well as it does makes me appreciate how far I have come since I started the BlueStamp program. It represents not only the effort I put in, but also everything I learned in the building process. I began with very little knowledge of Arduino, potentiometers, NRF24L01 modules, breadboards, and countless other things that are in my finished project. Now, I am so familiar with all the components of my project that I could build my robotic arm a second time. 

I also appreciate how my writing improved because of my documentation. I never had any experience with writing in the engineering field starting the program. I learned how to express my ideas clearly and in an organized manner. This is a skill that I will be using for the rest of my STEM career.

If I had more time to make modifications, I would add a chassis and wheels to my arm so that it could move around. This is something that I would have fun making and that would also be a new opportunity for me to learn more. It would open the door to learning about motors and other parts of vehicles. I am very proud of what I have built and am excited about my STEM education going forward.

The mechanical structure of the arm provides locations for servos at each of its four joints. This allows control over four different ranges of motion. One servo controls the base, one controls movement forwards and backwards, one controls movement up and down, and the last controls the opening and closing of the claw. Each of the servos receives a value from a different potentiometer, meaning that the NRF24L01 transceivers are communicating four distinct values. Instead of sending an integer value for each of the potentiometer values, I created an array, or a list, that holds all of the integer values. After the Arduino Nano transmits the array, the Arduino Uno receives the array and writes each index onto a specific servo. This process is looped so that the positions of the servos are constantly being updated. I created a circuit that supplies five volts to all of the servos, which is enough power to ensure the arm functions properly.

I started working towards this milestone by building the mechanical structure of the arm. The kit included four servos, though mid-construction I found that one was broken and had to be replaced. After that, I added three more potentiometers to the Arduino Nano’s circuit and made sure that all four potentiometers reported a value. Next, I created the variable that stores a list of all the potentiometer values. I programmed the transceiver in the Nano’s circuit to transmit it to the transceiver in the Uno’s circuit. I then coded the Arduino Uno to write each index onto a corresponding servo. Finally, I attached the arduino board and breadboard power strips to the robotic arm’s platform. I also rewired the servos’ circuit to make it more organized. For a wiring diagram of the final circuits, see figure 1.

Most of what I learned in this milestone related to increasing the scale of the project. I learned how to introduce more elements into my circuits without interfering with what I previously made. I also learned how to declare variables as an “array” type and how to add integer variables to arrays. The arm’s assembly kit is created by Microbotlabs.

To implement the Bluetooth transceivers, I learned how the NRF24H01 modules worked, and the purposes of each of the pins. Because I created an entirely separate circuit, I familiarized myself with the Arduino Nano, as I had exclusively been using the Arduino Uno before. I also learned how to program each of the transceivers to communicate with each other. The NRF24L01 datasheet can be found here.

To get to the first milestone, I learned how to use Arduino and to program in the Arduino IDE. Additionally, I had to learn how to read and record values reported by a potentiometer. I also became more proficient with circuitry and wiring. For example, I needed to create a circuit involving both the potentiometer and the servo, so I needed to learn how to incorporate a breadboard into my project.

I encountered a problem when I first connected the servo to the potentiometer. The potentiometer rotated the servo, but the rate at which it did it changed exponentially depending on the position of the servo. To solve this problem, I needed to add resistors in the circuit after the potentiometer so that the values reported by the potentiometer changed at a more linear rate.