In 2011, the main challenge was to hang inner tubes on a 10ft high rack segmented into 3 levels, and in a certain order for bonus points. Nearing the end of a 2 minute 15 second match, we would also have to deploy “mini-bots” to climb a 10ft vertical pole. Here’s the game animation for a better overview:
In six weeks (6) our team was able to design, build, and test our 2011 robot, named “Triangulation” after its side profile:
The robot itself featured:
- All wheel steering and all wheel drive geared for 14 feet per second or 4.2 metres per second
- Capable of “strafing” in all directions while maintaining full drive power and traction
- Full gear drive for maximum reliability with 2 stages of reduction and 4″ wheels
- Encoders to track steering angle and wheel position
- Limit switches for automatically aligning the drive modules and preventing damage due to over-rotation
- A motorized claw
- Capable of efficiently picking up inner tubes
- Able to rotate inner tubes for precise positioning on the scoring rack
- Round belts used to grab and compress inner tubes
- A single jointed, telescoping arm
- Pre-programmed positions for picking up and scoring inner tubes
- Automated cycle for hanging inner tubes
- Rotary stage driven by a worm gear motor for holding positions
- Telescoping stage driven through round belts
- Encoder used to track arm position and limit switches at end stops to prevent damage
- Minibot deployment
- Pneumatic cylinders coupled to drawer slides for linear deployment
Videos courtesy of Chris Choi:
Finger Lakes Regional:
Greater Toronto and Waterloo Regionals:
The general concept was to pickup tubes on one end of the robot, then hang tubes without having to turn around. This strategy was rather effective and the robot performed well in competition, finishing in 2nd, 3rd, and 4th in the official competition at the Greater Toronto Regional, Waterloo Regional, and Finger Lakes Regional respectively. In the off season the robot won 1st place at Brunswick Eruption hosted by Team 25.
With a swerve drive, design of the overall robot was extremely important. During the design process, there was argument over whether to use a simpler mecanum drive train instead of a swerve drive train. In the end it there was a compromise to design a chassis for both, adding another layer of complexity. I was largely responsible for the drive train and overall robot design, but unfortunately at the time of writing, I’ve lost the models and only have the following screenshots from early in the CAD-ing process.
In all, the robot was a great machine which taught me a lot about machine design and engineering in general. In essence it was a simple robot which was well thought out and well designed.
I have since revised the drive modules to be lighter and easier to manufacture, as well as cheaper. Since these drive modules never made it into production and shouldn’t be considered complete, they are completed to a point where another team could easily integrate the drive modules into a competition robot.
One intended for heavier duty applications and using VEXPro gears (Download here):
One Intended for lighter duty applications (Download here):
Feel free to contact me for any more details on swerve drives, and see the 2012 robot’s drive train for what not to do.