Robotics and Mechanics B – Project One – Chunky Monkey

Hi, my name is Alexander Achcar and in robotics and mechanics class we have been working on a sumo-bot project. Through all my problems, I finally created to the best of my work, a functional robot that could move, attack, and sense using both online programming and lego/gears. Following the same general idea, I came up with 3 different prototypes that aided to my end product.

Prototype 1: My first prototype was based off of the idea to have swinging claws at the front, and a protective shield at the front to block attacks. At the start of our project, as the pictures show I had a very basic track based movement system which made my vehicle only available to move laterally, and not able to turn. I had one claw, which attached to a gearing system went back and forth, up and down. This was protected by two shields placed beside the claw to make sure that it didn’t get whacked off in the process of a fight with another robot. However, It didn’t really have a steady hold, as I will later describe in my problems section.

Prototype 2: However, I didn’t really feel satisfied with my prototype, so I took it apart but stood with my first concept of claws surrounded by shields. This time, using the same movement and buildup structure, I organised a series of claws, four to be exact, connected to the top motor that didn’t rely on gearing and instead just rotated because of the program. I then fastened a thick layer of blocks together and stuck them onto the front of the robot just under/in front of the claws. This, I then thought would be the final change to my weapon system. Then, as we were instructed to have to be able to add and remove our NXT brain, I had to create a holder to place the brain. My vehicle, already being unstable had more of a problem as the heavy block was to be added to the top of my robot. To do this, I created a flimsy, axel connected structure that could hold, and easily detach the brain, as shown in the pictures above.

Prototype 3: Lastly, my third and final prototype forced me to re-arrange the front of my robot. To start, I decided that having a gearing based weapon system would be a lot better. I took to reviewing the gearing concepts then decided on creating a gearing up concept to have the axel spinning fast, but not too strong. This would ensure to rip things at the front of the robot, as well as making it look really cool in action, as shown in the video. Then, after performing a drop test, I learned that with the brain, my robot would be insanely unsteady, and would have to make the top lighter, or the bottom heavier. I then set about adding more bricks to the bottom, both tightening the connection between top and bottom, and also making the bottom heavier, more able to support the bottom.



1: Claws (No Gearing Involved): My first problem revolved around my claws, of which were just motor based. To advance comprehension of gearing concepts, I decided to demonstrate a gearing up motion to rotate my claws back and forth. However, my robot wouldn’t work if I had to make it double sided claws, so I limited myself to using two claws, both with their independent gearing system on opposite sides of the motor which they were running on. I then connected them to base of my robot through different styled blocks, forcing the motor to just spin the axel back and forth in order to lift the claw up and down in a fast motion.

2: Weight to the top: My next problem involved my robot being too unbalanced, having most of it’s bulkiness focused at the top, and my bottom only having the wheels. THis therefor, made my robot shake from side to side when it rolled along the ground. It also made my robot potentially fall when my claws were swinging really quickly. To solve this problem, I decided to both add weight to the bottom, but also fasten the top of the robot to the bottom more tightly, ensuring that it wouldn’t sway, but hold perfectly vertical with my wheels. To do this, I took the semi-diagonal long pieces and laid them along the length of the vehicle, pegging them where I could, making the vehicle harder to sway.

3: Program: Following up, my third problem entailed the program, where I had trouble both calibrating, and thinking of what to do. To calibrate, I took the vehicle and placed sensors and took what they read on the white line surrounding the black arena, using that to make my robot turn, however, with my inability to turn, as explained in the next problem, I had nothing to do when it went backwards. Next, I made an error in my program where I accidentally made my robot do the same thing when it hit the line, and when it plain off didn’t. I also had forgot to set my robot to walk forever until I realised that I only had it running for a prolonged amount of time.

4: Not able to turn: Furthermore, my fourth problem involved my vehicle not being able to turn and change direction, this therefore made me really vulnerable to vehicles with high mobility that can turn around my robot and hit me from the side. This was because my motion was based on the the tire tracks, which rotated from the front motor, only relying on one moving axel, and the rotation of the tracks to push the second for balance. This, therefor, provided zero angle for turning since the motor would have to turn underneath the top structure, and that would both collapse and require another motor, of which I didn’t have.


Video: Robot

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