Difference between revisions of "DEWBOT IV Lift-Catapult"
MaiKangWei (talk | contribs) |
MaiKangWei (talk | contribs) |
||
| Line 3: | Line 3: | ||
*When deployed, never extend beyond... | *When deployed, never extend beyond... | ||
*Knock Trackballs off the Overpass by driving directly underneath | *Knock Trackballs off the Overpass by driving directly underneath | ||
| − | *Pick Trackballs off the | + | *Pick Trackballs off the playing field |
| + | *Automatically capture Trackballs | ||
| + | *Possess Trackballs | ||
| + | *Hurdle Trackballs over the Overpass via the catapult | ||
| + | *Place Trackballs on the Overpass at the match end for bonus points | ||
| + | |||
| + | A double-extension lift was required to allow the Robot to both fit within the starting envelope and to reach a height sufficient to place the Trackball back onto the overpass. | ||
| + | |||
| + | The Fork itself needed to be as wide as possible (to securely cradle the Trackball) and needed to articulate to (3) discreet angles: 1) horizontal to capture Trackballs (and release them); 2) 20° raised to securely possess the Trackball; and 3) As close to 90° (which was 70°) raised to fit within the starting envelope. Since pneumatics are a good choice when 1 or 2 discreet are required, pneumatics were selected to control the Fork angle. | ||
| + | |||
| + | |||
| + | |||
| + | Very early in our design process, we identified (8) key "modes" for the Fork-Lift-Catapult. | ||
While air cylinders actuate the Fork and Catapult, a motorized winch controls the Lift elevation. The winch has a double spool with opposing winding and so pulls the Lift both up and down via a cable and pulley arrangement. This arrangement allows us to enjoy the elevation range of a double extension Lift while using only a single drive source and control. Lift elevation is controlled via PID (Proportional, Integral & Derivative) control using an encoder on the Winch drive shaft. A limit switch at the bottom of the lift travel zeros the encoder count. There is also a limit switch at the top of travel for safety. | While air cylinders actuate the Fork and Catapult, a motorized winch controls the Lift elevation. The winch has a double spool with opposing winding and so pulls the Lift both up and down via a cable and pulley arrangement. This arrangement allows us to enjoy the elevation range of a double extension Lift while using only a single drive source and control. Lift elevation is controlled via PID (Proportional, Integral & Derivative) control using an encoder on the Winch drive shaft. A limit switch at the bottom of the lift travel zeros the encoder count. There is also a limit switch at the top of travel for safety. | ||
Revision as of 00:30, 5 June 2009
A combination Fork-Lift / Catapult was designed for scoring. This lift was designed to:
- Start a match within the 28" x 38" x 60" envolope
- When deployed, never extend beyond...
- Knock Trackballs off the Overpass by driving directly underneath
- Pick Trackballs off the playing field
- Automatically capture Trackballs
- Possess Trackballs
- Hurdle Trackballs over the Overpass via the catapult
- Place Trackballs on the Overpass at the match end for bonus points
A double-extension lift was required to allow the Robot to both fit within the starting envelope and to reach a height sufficient to place the Trackball back onto the overpass.
The Fork itself needed to be as wide as possible (to securely cradle the Trackball) and needed to articulate to (3) discreet angles: 1) horizontal to capture Trackballs (and release them); 2) 20° raised to securely possess the Trackball; and 3) As close to 90° (which was 70°) raised to fit within the starting envelope. Since pneumatics are a good choice when 1 or 2 discreet are required, pneumatics were selected to control the Fork angle.
Very early in our design process, we identified (8) key "modes" for the Fork-Lift-Catapult.
While air cylinders actuate the Fork and Catapult, a motorized winch controls the Lift elevation. The winch has a double spool with opposing winding and so pulls the Lift both up and down via a cable and pulley arrangement. This arrangement allows us to enjoy the elevation range of a double extension Lift while using only a single drive source and control. Lift elevation is controlled via PID (Proportional, Integral & Derivative) control using an encoder on the Winch drive shaft. A limit switch at the bottom of the lift travel zeros the encoder count. There is also a limit switch at the top of travel for safety.
Five relays (spikes) are employed to operate the pneumatic system. One operates the compressor based on input from the pressure switch. The other four each operate one solenoid valve. Three of these solenoids actuate the Fork and Catapult system, while the last is used to shift the transmissions.
A restrictor valve in one exhaust port of the catapult solenoid provides asymmetric operating rates. As a result, we can “Arm” the catapult slowly (so that we don’t lose the Trackball) and fire it quickly.
category: DEWBOT IV
