MAE 106 Final Project ReportB5 Group 3: Guillermo Jimenez, Daniella Lopez, Alexander Chen, Yvonne Liu

June 13, 2014

Section 1:

a) Mechanical and software design After brainstorming many designs, the group decided to try and keep our design as simple as possible. We chose to create a hopper/kicker because it is much easier to tinker with than a crank driven robot. We also figured it would be less time consuming and simpler for fabrication. Materials: In order to reduce the overall weight off the robot, the chassis was made entirely of wood. Only small portions of metal were used for the steering and the brace for the piston, along with nuts and bolts. The Chassis: The chassis consisted of two circular plates and four cylindrical columns to support the tire above. Having a circular base allowed us to keep everything restricted under and within the dimensions of the tire. It also served as a shelf to place all the electrical equipment because of its large surface area. Driving mechanism: As for the driving mechanism, the piston was braced in metal and mounted to a sloped piece of wood which was placed approximately at the center of the plate. The brace reduced any horizontal movement from the piston. The wood placed the piston at a 45 degree angle from the horizontal. This angle caused the robot to rise as the piston hit the ground, so a hinge was placed at the top of the piston connecting to the sloped wood. This allowed the piston to have a vertical degree of freedom and no longer lifted the robot. A rubber stopper was added to the bottom of the piston leg to create more friction with the floor, and was connected with a coupler to elongate the leg. In order for the robot to increase speed, we shortened the tubing between the piston and solenoid. Steering mechanism: The steering technique used was an Ackerman steering system. It consisted of a four bar linkage system of a tie rod, connected to two steering arms which were connected to another bar with two kingpins. The steering arms were about 30 degrees from the vertical. Connected to the center of the tie rod was the counterweight used in the resonance lab. The counterweight would move left or right with the brush motors motion and would thus control the overall steering. In order for the motor to stay in place allowing only the pin to move, it had to be mounted to the bottom chassis plate and held with a bracket.

Software: The main idea for the code was for the piston to fire at a high rate and have a desired position for the motor (steering) at a time of our choice. This code was a combination of a blink code without delay, and the lab 3 motor code with few modification. The sensor code was not used since the Arduino only allowed for two interrupts and the sensor code would have added another. Instead we used time, rather than distance as out method of moving. As we tested the robot with our program, it worked fine. It wasn’t until later that we realized the program wouldn’t be accurate enough for the competition field, since we had tested it on smooth ground. The deep grooves and cracks on the competition ground created too many variables to our desired path. Also because our steering was not tightly connected it was easy for the grooves to create a large angle change. Something we could have done to the program to account for this is to have a code that senses the motors desired position and if it’s not our desired then to calibrate the angle back. Since the group doesn’t have much experience in programming and the limited time after we had tested, we were not able to enhance the code to our liking. Another problem we ran into was the distance our robot traveled. A stop code was attempted to stop the blink code and the steering code after a certain time we chose, but it was not successful. In order to waste distance we made the robot turn after a few seconds to make the robot run a full circle with a radius of 2.12ft which is the distance from the center of the tile to the center of the 3x3 box. This allowed the robot to circle around to its original spot, and have enough air to move to another tile. Ultimately, since none of us were experienced in programming we managed to figure out how our robot could work without changing or enhancing our working code.

b) CAD of the Robot