Well, I set up a 2 tile programming challenge in my living room. I built a little A frame mockup that has the 14 degree tilt and the dimensions of the actual roundup ladder face.
See video of the 25 step programming challenge here:
A very simple autonomous script which is embedded in the RobotC code causes the robot to move forward while holding heading, pick up 4 tubes and head toward the movable base goal. It is allowed to bump into the goal since a special space bar is deployed by servo to keep the robot from over running the goal and maintain the exact spacing needed for a drop. A timer expires and the drop begins. The plunger or spike has a grip that is servo controlled to three positions: HOLD, DROP ALL, DROP ONE. The DROP ONE is done twice and the DROP ALL is performed last to let the remaining two tubes score. The robot then backs up a little and lowers the lift for a line tracking function that continues until it backs into the A frame. This is signaled by a bumper switch. The robot then does a 180 deg turn and raises the lift to clear the pick up mechanism from striking the 6 in high crossbar on the bottom of the A frame.
Ready for the finale: The robot must tilt 14 degs in order to grab the A frame. This is done using the robots momentum. A full speed burst forward followed by a sudden full speed reversal does the trick. The robot tilts against the A frame and then extends higher to allow the grippers to reach around the sides of the A frame. The lift is then lowered until the grippers grab the sides of the A frame and then the bottom is raised above 6 inches.
The lifts have a 36 tooth drive gear connected to the Vex 2 wire 393 motors. This allows quick movement of the lifts and yet retains enough torque to lift the full weight of the robot. Special lift geometry allows the lifts to travel over 19 inches so it can do the 18 in above ground high hang in theory.
More Roundup Mentor Bot:
Complete RobotC code in case you missed it.
Posted pictures on the vex site:
More blog stuff: