373 Project: Computer Aided Trebuchet
Team Members: Sachin Doshi, Robert Schroder and Kyle Williams
The trebuchet was the pinnacle of medieval siege engine technology. Our project consists of a trebuchet equipped with sensors and mechanized components that allow it to automatically detect and fire at targets.
Project Components:
Geared Motor A geared motor rotates the turntable the trebuchet and sensors are mounted on. The motor runs at a constant speed and deactivates when a target is detected within the range of the trebuchet.
Ultrasonic Sensors A pair of ultrasonic sensors determines the range of potential targets. Theses sensors are activated by sending them ten millisecond input pulses. The duration of the output pulse from the sensor indicates the targets range.
Servo Motor A servo motor adjusts the length of the firing string which controls how far the trebuchet projectile (a mouse ball) will travel.
Nintendo Controller A Nintendo Entertainment System Controller is used to control the trebuchet when it is not in automatic mode.
Trebuchet The trebuchet itself is approximately one-fiftieth the size of the largest trebuchets that were deployed to assault castles and other heavily fortified targets. While much smaller, our trebuchet manages to precisely and reliably strike unsuspecting civilian targets at distances ranging from seven to twelve feet.
Primary Project
Challenge:
By far the most challenging aspect of this project was setting up the ultrasonic sensors. Although the sensors measure distance accurately, they have a very wide angle of detection. This was a problem for us as we wanted the trebuchet to fire only at targets that were directly in front of it, and not thirty-five degrees off to one side. We ultimately solved this problem by using two ultrasonic sensors and positioning them so that their detection fields overlapped slightly. By comparing the ranging data from both sensors the trebuchet could determine if there was actually a potential target at its current heading.
Special Thanks: (in
no particular order)
Mark Brehob For allowing us to use a trebuchet as the basis for a 373 project (let it be known that no one was seriously injured during the development and testing of this project)
Matt Smith Without whom this project would never have reached a fully functional state
Ron Hagiz For highly useful debugging advice and servo motor control information
The French For providing the historical impetus to build a weapon capable of launching a 300 pound projectile a distance of 300 yards