Here are the artifacts from a project the Bumble Bees did a the start of this season. We provided instructions for each team to build a different type of drivetrain, and then tested and compared all of them. This project was really fun, the kids learned a lot, and it opened their minds to different design options. I’m hoping that other mentors can share projects or activities that they have done with their teams.
At the time we had five teams, so there are five different designs. Of course you could run the project with fewer teams. One other type of drivetrain that could be added is a crab drive. If there is interest I will create instructions for it.
The designs are fairly simple and are intended for participants without much experience. However, you should be able to build the clawbot before trying this. Each drivetrain should take about 2 or 4 hours to build, depending on experience. Take your time. Expect to make mistakes and have to do some rework. Don’t get frustrated, rework is part of the process.
Before you start make sure that you have all the needed parts. Some of the designs require more than the Super Kit. The additional parts you may need come in either the Competition Add-On Kit (for chains, tank treads, and omni wheels), the Foundation Add-on Kit (for more plates beams and corner connectors), or separately (additional omni wheels).
The instructions were made using last season’s parts. Consider using the new plastic shafts instead of the metal shafts in the instructions.
Hopefully you will find the instructions useful, but there is no claim that they are professional quality, and certainly not perfect. If you find an error feel free to go ahead and update the source document (they are editable to anyone with the link). Or send me a message and I’ll make the update.
Although it is possible to use the Driver Control program, it won’t be easy with the 4 motor drivetrains. Below is a link to sample Robot C code that will make driving much easier. To use the sample code you will need to have Robot C installed, click on the link to get a trial version.
Editable Design docs: https://drive.google.com/drive/u/0/#…EJwMFo5TnFIeEU
Robot C Download: http://www.robotc.net/download/vexrobotics/
Once you have the drivetrains built you are ready to run them through a series of tests. The following tests: Tug of War, Drag Race, Catch the Other Robot (round track), Obstacle Course, Mine Field. Ideally each test would show the strengths of a different drivetrain.
Tug of War: Connect two robots together back to back with Vex IQ chain or tank tread. On GO the robots pull in opposite directions. The first robot to pull past a predetermined finish line wins. Set the finish line so that one robot must pull the other about 2 ft or 1/2 meter. Use a bracket ranking system to determine which robot is the best.
Drag Race: Line up all robots behind a starting line facing the same direction. On GO all robots drive forward as fast as they can in a straight line to the finish line. Set the finish line 10 or 15 feet (~4 meters) from the starting line.
Catch the Other Robot: This is a round track race with 2 robots. They start directly opposite to each other on track and go around in the same direction. The robot that can catch the other robot wins. Use a bracket ranking system to determine which robot is best. Results will vary base on driver skill, especially for the slide drive.
Obstacle Course: Setup a course that requires robot to go around, over, under, or move objects to get through. Same course for all robots, so you must make something that can be reset. We used a Vex IQ field with different IQ parts stuck in the holes. Keep track of the best time. Results will vary base on driver skill.
Mine Field: Setup a course that robot must get through without bumping into anything. We used a field for this too and placed blocks so that it progressively harder to maneuver past them. Track how far each robot gets before it touches a block, and how long it takes to get to the end, if they get that far. Results may vary based on driver skill, especially for the slide drive. Note, that robots will a smaller foot print also have an advantage.
- Have the students compare their drivetrain design with the others. [LIST]
- How are they different? [LIST]
- Mechanically #motors, types of wheels, gear differences, wheel orientation, size, height, center of gravity...
- Let the students know before they start that the robot drivetrain that they will be building will be taken apart when the project is over. They will be proud of their work, and will want to keep it forever. However, the parts will be needed for other projects, and chances are that some other drivetrain is a better fit for this year’s competition. It is also an important lesson not stop striving to improve, and making changes is part of improving.
- Conversely, they shouldn't be disappointed if their robot does not perform well in some or many of the challenges. They can pick a better design for their own competition robot.
PowerTurtleDrivetrainBuildInstructions.pdf (1.59 MB)
DragsterDirvetrain.pdf (2.06 MB)
TankDriveBuildInstructions.pdf (1.8 MB)
SlideDriveBuildInstructions.pdf (8.67 MB)
6OmniWheelBuildInstructions.pdf (9.46 MB)