Drivetrain
The drivetrain section was designed to provide high-torque, since the acrylic design made the robot much heavier than its counterparts. We decided on the smaller set of motors because they provided the same stall torque, though at a lower no-load speed. With the smaller profile, and lower weight, they appeared to be a better choice than the other motors. Unfortunately, their smaller shafts also made coupling the motors and wheels more difficult, as the spider coupler created off-center rotations.
These off-center rotations provided the biggest challenge to getting our robot to drive in a straight line. By adding shims to the shaft, we were largely able to offset the shaft enough to counteract the rotation problems. Some problems still existed, but they were minimized.
Another problem we faced was that the use of a coupler made the wheels largely unsupported. The caused large wheel camber and poor power transmission, so the system was redesigned to provide better support for the 1/4" shaft.
Fortunately, we were able to find hubs for the rollerblade wheels we used. Those allowed us to easily secure the wheels and drive them without needing to create special adapter pieces. The hubs were instrumental in simplifying the drivetrain assembly, since many previous and current robots had problems with securing the wheels.
Finally, the drivetrain was powered by an L298 so it was fully bidirectional, allowing the robot to translate forward and backward, as well as rotate.
These off-center rotations provided the biggest challenge to getting our robot to drive in a straight line. By adding shims to the shaft, we were largely able to offset the shaft enough to counteract the rotation problems. Some problems still existed, but they were minimized.
Another problem we faced was that the use of a coupler made the wheels largely unsupported. The caused large wheel camber and poor power transmission, so the system was redesigned to provide better support for the 1/4" shaft.
Fortunately, we were able to find hubs for the rollerblade wheels we used. Those allowed us to easily secure the wheels and drive them without needing to create special adapter pieces. The hubs were instrumental in simplifying the drivetrain assembly, since many previous and current robots had problems with securing the wheels.
Finally, the drivetrain was powered by an L298 so it was fully bidirectional, allowing the robot to translate forward and backward, as well as rotate.