University of Southern California The USC Andrew and Erna Viterbi School of Engineering Pre-College Summer Programs - Student Portfolios

Transportation (CE,CSci, ME)
Students will:

  1. Build an automated materials transporter, from a Vex robotics kit, capable of carrying 3 standard red bricks.
  2. Build a foot balsawood bridge, which
    • Spans a 3 foot space between 2 tables
    • Has a minimum clearance of 1ft across the span
    • Will support a Vex rover carrying 3 standard red bricks across
    • Has a ramp on each side from table to bridge surface

Day 1 Group 4

Bridge

We designed the bridge, and also built its base; the base was improved by the next group (1) the next day.

RV

We tried to figure out what was the best way to build this compact car; we half-finished a prototype, which the next group took apart to try and build a sleeker model because the prototype was more than half the length of the bridge.

 Day 2, Group 1: Cindy, Eric, Kimberly, Kylie, Victoria

Vex Robotics

Group 1 began the construction on the Vex Robot by examining notes made by the previous group. We were instructed to replicate the tire and gear design that was built on the right side of the robot. After we completed this task, we faced a challenge in proportions. The requirements stated that the bridge had to be twice the width of the Vex robot. However, the bridge was approximately 15 inches wide while the robot was 9 inches. Due to this challenge, we decided to alter the size of the Vex robot because we were unable to make the bridge wider due to supply limitations. As a group, we decided make the width of the robot base structure narrower. When we shortened the length of the steel base, the motors clashed, so we adjusted it accordingly by placing the motors one above the other, rather than side by side. This adjustment allowed the base structure to be narrow. As we changed the width of the Vex robot to 7 inches, we met the proportion requirement. However, another challenge arose because the bricks would interfere with the tires and gears when we placed it on the steel base structure. To accommodate this change, we decided to create a steel basket to be placed above the robot. The Vex robot then resembled a truck in structure. We also finished creating the structure of the Vex robot and tested out the motorsby programming the robot to move straight. We advised the next group to work on the programming for the Vex robot and stabilize the basket on top of the robot.

Balsawood Bridge

Our goals for the bridge and the ramp were to design them such that the Vex robot would be able to easily climb the ramps and cross the bridge twice without neither the bridge nor ramp breaking. The previous group had built the platform for the bridge, but it was really weak and could barely hold one brick. To solve this, we added more supports onto the bottom by creating X's of reinforcements. The bridge was 3 feet long, which was unworkable because the distance between the tables was supposed to be 3 feet. As a result, we added 3 inches of wood onto each side, and further reinforced it so that all the pressure would not concentrate in the middle. We also tried to build a span to hold up the bridge. We decided to put 18 sticks glued together, which actually held up the bridge. However, we were unable to finish all 4 corners. In addition, we had difficulty building the ramps because we were unsure about which design would be optimal to use such that we used as little wood as possible, due to the material constraints, and that the robot would still be able to carry the three bricks up the ramps. We decided to do ramps that would not span the entire width of the bridge, instead setting on a ramp underneath where each wheel would go. The ramps that we built were strong enough to hold the 3 bricks without bending.

The next group would need to finish the ramps, build the trusses to keep the bridge up, and make sure that the construction of the bridge was 1 foot above the table.

 

 Group 2 Day 3

We finished building the parts for the supports but haven't actually glued them opnto the bridge.

We finished the trusses. The 4 ramps are finished and are sturdier.

For the car, we rebuilt it.

Group 3 Day 5


Vex Robot


We continued working on the Vex Robot, and inspected the notes that were left by the group before us. There were a few adjustments that needed to be made, including adding more to the program on the computer, and adjusting the time that the robot was going to be crossing the bridge. We also had to build a basket that would hold the bricks in place without falling as the car moved up the ramp. We continued working on the Robot, but our group ended up taking the robot apart and starting from scratch, but kept the same design. We aligned the wheels and tightened them. We adjusted the height of the Robot, because it needed to be less than 9 inches, so we adjusted it to 7 inches. We also added a small basket in order to support the weight of the bricks. In the end we were able to time the robot and programmed it for 8 seconds, which gives it more than enough time to go over the ramp, across the bridge and around. The car works, and is able to support 2 bricks and also goes straight!

Bridge

Our group added the bottom structures which served as support. We also connected the ramps to the bridge and fixed minor adjustments.