ROBOT PROJECT SUMMARY

The goal of this project was to design and build a hydraulically operated robot to grasp a tennis ball, elevate it above the height of a designated container 5.5" tall with an inside diameter of 3", rotate it a minimum of 90 degrees and release it into the container. Extra credit would be awarded to the team who completed the task the quickest and any teams robot that could rotate 360 degrees. The use of prefabricated parts for their original purpose was not permitted. We were given 6 hypodermic syringes and rubber tubing which was to be used for the motion of our robot.

When I first heard the goal of the project I immediately though of ways on how to rotate the machine because this would be the most complicated part. I first thought of a geared pulley system that would take minimal movement of the syringe to turn the arm. This design we decided was too complicated for it too work successfully. Next I remembered how old drag links, stationary cranes, rotated. They basically have two hydraulics connected to wire rope on either side that are wrapped around the main pivoting body. They push and pull to move the wire rope that turns the pivoting body. We weren't sure on how to do this so I asked Ian Creelman from a different group to help us. Ian figured out we would need a dowel of ¾ of an inch for the arm to rotate 360°. We tried this quickly too see if it would work and it smooth and efficient. I was happy with the design so we began on final assembly of the rotating arm.

Next we needed to figure out how to pick up the ball. I thought of an excavator, a piece of hydraulically controlled equipment designed to dig up dirt, elevate it and rotate to drop it off elsewhere. So for the arm I looked at how their hydraulics worked of the excavator. I saw an excavator has four hydraulics on their arms. We could only afford to use one hydraulic set (two syringes, one for pushing/pulling and the other for controlling) on our arm because the other two were going to need to be used for picking up the ball and rotating it. Thus we could make only one moving arm which would make it difficult to position the arm over the ball. We designed arm system that had one arm coming from the base with a 45° degree angle on it and a second arm pinned to the end of the fist. The first arm was designed to position the second arm in an optimal place for picking up the ball. We used a piece of one-inch dowel that we cut to size and angles with the miter box. We used the drill press and made a hole for a bearing to fit in. Next we lathed down the arm to fit in the bearing. Also we sanded down mid portion of the first arm where the string would wrap around. This would make it so the arm could rotate 360°. We used epoxy to glue the two part of the fist arm together to make the 45° angle. Next we used the ban saw to cut notches in the dowel so it could rotate freely when pinned. A syringe was to be hinged underneath the two arms. We fabricated cabinet hinges to wrap around the cylindrical arms and syringe and used screws, zip ties and glue to hold them in place. My partner created the ball grabber. He used standard household tongs. They were bent to better pick up the ball. A syringe was secured in-between the handles with duct tape. This was a simple yet very effective way of picking up the ball.

At the beginning my group mate and I did not interact very well. We were having communication problems. We then talked things out, I needed listen to his input and he needed to communicate more. Once this happened we interacted well and efficiently. To help with communication we used drawings to illustrate our design ideas. This proved to be invaluable. Compromises were not needed to be made because we agreed on things once our communication problems were solved.

My role in our group was as a leader. I budgeted our time and made sure all things were done right. I also helped with the design and implementation of it. I did the majority of the scale drawings. My partner developed the device that grabbed the ball and it worked very well. He also helped with many aspects of the construction.
Once the robot was built there were various problems. The arms were falling out of the base during testing. To remedy this we put a bolt through the bottom of the base up into the arm. To reduce friction we used a washer with plenty of grease. Another problem we had was tying the string to the syringes and around the dowel. This was tricky because if done wrong it would bind and not turn. Also the string to rotate the arms needed to be tied really tight to the end of the syringes. To make things easier we tied the sting to hooks connected to the top of the syringes. We turned the hooks like tuning a guitar to get the proper tension

Our project tested well. It completed the task in a decent amount of time and was able to rotate 360°. However if I were to do this project again I would do it completely differently. I would make something much more efficient and simpler. Maybe it would consist of an arm that picks up the ball and puts it on a ramp that goes around and drops it in the cup.

The major skill I improved upon during this project was working well with others.
This was a major test of my patience and communication abilities. I learned important critical thinking skills, these types of exercises give you experience that you can put to use in many aspects of my life. Also I was able to brush up on my manual scale drawing skills.