Leah+and+Emma+Final+Robot

Team:
Leah Tinberg Emma Tesler

Bot description:
We used an original model in building most of our robot for Botball. Our basic design is from Constructopedia v2.1, and it is called the "Simple Side Attachment." We chose this model because it was low and wide, which made it less likely to tip over if someone hit it. We attached a large swivel wheel to the back to give it full mobility when turning and moving backwards. We chose the large wheel so that it would not stick or get caught on the back of the robot (like the smaller swivel wheel did) and also so that the bot could make it up the orange, foam mats without getting caught. We also attached a trapper contraption to the front of the robot in order to trap a ball while the robot retained the ability to move while the ball is trapped. The trapper moves up when a button on the game controller is pressed, moves down when another button is pressed, and stops when yet another button is pressed. It is important to remember to stop the trapper after it reaches the position we want, or else it will continue to move up or down and will interfere with other parts of the robots. Our robot design is succeeding. One complication is that when the robot reverses directly from going forward, it rises up because the back wheel is very large. It then moves backwards while elevated, seemingly balancing on its three wheels. This hasn't caused any problems yet, but we just have to be careful when it is in this elevated position because it is more tip-able, especially when riding onto the mat while moving backwards. On this note, a convenient feature of our robot is that the large back swivel wheel allows the robot to ride directly onto the game mat, although it is much more stable when moving forwards onto the mat. This is extremely helpful because it means that we do not have to use the ramp every time we want to get on to or leave the mat. This saves us time, especially useful during the timed Botball challenge. Our robot is controlled by a game controller. Each joystick controls a wheel motor (either left or right), and the buttons on the top of the controller, as mentioned before, operate the ball trapper.

Design & Building Process:
From the beginning, we knew that we wanted a robot that was low and wide, so that it would not be knocked over by the robots of our more violent classmates. As we said before, we used Constructopedia and chose the design that mounted the motors in the most stable way. Once we had this basic design, we tried to attach a small swivel wheel onto the back so that our robot had a wide range of motion and would not jerk when changing direction. But, when we tried to drive our robot with the small back wheel, it rubbed against the underside of the bottom of the robot and could not turn smoothly or move onto the mat without the help of one of the ramps. So to fix this problem, we exchanged the small swivel wheel for a much larger one. To attach the new wheel we used an angle beam that bends twice, to make sure that the robot was lifted far enough off the ground so that it wouldn't drag. After we changed the wheel, our robot drove nicely. We had known from the start that we would want to include some sort of contraption to grab or trap the balls, and we began to work on this. We knew that we could only add one more motor (because there is only space to connect 3 motors on the NXT brick), so at first, we tried to conceive a design in which we created a claw using gears to pick up the ball. We couldn't find a design online to help us though, so we decided to go with the idea of building a simpler ball trap that just moved up and down. By stacking many angle beams and "threading" an axle through them, we built a structure that could encase the ball. We mounted a third motor to the top of the NXT brick, and attached the trapper so that it could hang over the front of the robot. Finally, we attached a few straight beams to the inside of the trapper, so that it would (1) limit the space the trapped ball had, making it less likely that the ball would roll around in its trap and interfere with other things, and that it would (2) project the ball forward when the trap opened. Despite a few building and programming challenges, such as the width and programming of the trapper, we retained the basic design that we had wanted from the start--a low, stable robot (that elevates slightly when moving backwards) with a trap on the front.

In-Game performance:
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Here is our Lego Digital Designer model: Here is the code for the robot controlled by the game controller: