DEWBOT IV 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
