Computer Targeted Trebuchet Seth Katz and Matthew Leese, Rochester Institute of Technology Trebuchet Design Overview User Interface Medieval trebuchets were designed to throw large rocks in the general vicinity of a besieged castle. Because they were usually stationary in the siege, there was little need to change where it was aimed. The user interface is provided via the computer. The main screen consists of a targeting area. To select a target, the user clicks on the screen at the desired target location. The computer then commands the trebuchet to change the range and azimuth appropriately. At that point, the trebuchet can be armed, and then fired. If a different target is selected, the trebuchet must be rearmed before it can be fired. The Computer Targeted Trebuchet is a computerized version of the medieval siege weapon. A conventional trebuchet throws a projectile by the use of a counterweight. The counterweight is attached to pivoting arm. On the other end, a sling is attached. The projectile is placed inside the sling. In order to allow for computer targeting, two axes of movement were added to the trebuchet: the movement of the counterweight and the rotation of the trebuchet to change its direction. The movement of the counterweight allows for the range of the trebuchet to be modified. The rotation of the trebuchet allows for the azimuth of the trebuchet to be changed. Side View of Trebuchet The design of the Computer Targeted Trebuchet is very similar to those of medieval times, however much smaller. The only real modification from the classic design is the addition of a movable counterweight, which allows the range of the trebuchet to be changed. By attaching the counterweight to a linear actuator, the counterweight placement can be controlled very accurately. Computer GUI Interface Top View of Trebuchet Arm In order to control the azimuth of the device, the trebuchet is mounted upon a rotating base. This is driven by a stepper motor geared down to provide enough torque to turn the unit. The firing procedure is controlled by a release pin mounted to a servo. This allows the firing process to be repeated consistently for accuracy. Computer Targeted Trebuchet System Overview The Computer Targeted Trebuchet consists of three connected components: the trebuchet, the embedded controller, and the computer. The trebuchet is the device which actually launched the projectile. It also contains the components needed for the physical movement of the counterweight and the base. The embedded controller is responsible for controlling the movement of the actuators used to change the range and the azimuth. It also is responsible for controlling the firing pin on the trebuchet. Finally, the computer provides the user interface to the operator. The embedded controller and the computer communicate via RS-232. Trebuchet Embedded Controller Computer Detail of Firing Mechanism Trebuchet In Action Team Operational Specifications Seth Katz seth.m.katz@gmail.com Maximum Range 20’ Minimum Range 10’ Rotation -30 to 30 Accuracy 1’ radius Misfire Rate 25% Embedded Controller Trebuchet Computer Matthew Leese mleese@gmail.com System Block Diagram October 27, 2005