Solid Model

The assembly and the motion study of the catapult were completed. During the creation of the assembly some problems were detected. Spencer Crane has made the assembly, and Gabriella Mastrogiuseppe added parts and did the motion study. The problem was with contacting bodies. In fact, the lever of the catapult would go over the bar even if in the contact group they were both inserted. Also we were uncertain if there should be a servo motor in the assembly. For the study motion I utilized a motor rotating counterclockwise.

Gabriella and Spencer 

Sourcing Servos and Additional Ideas

We had a small team discussion about acquiring the parts needed for the project.

The wooden components will be bought last, after the entire assembly has been completed and tested.  This will give us more flexibility in getting the electrical and coding side of the project done.

Of the 3 servos required for this project, 2 will likely need more strength than the small ones included in our 

Arduino kits.  The catapult release servo will not need as much torque, and can be supplied by the Arduino kit.  The 2 stronger servos in the design can come from my old RC stadium truck.  Since this truck is a 1/10th scale stadium truck requiring relatively strong servos for steering, these servos will provide us with enough size and torque for the project.

We also bounced around the idea of adding LED lights and an LCD panel to indicate the control setting of the catapult, but decided to put this off until we can get the catapult working properly.  Once the coding is done and controls are tested with the Arduino board, we will start working on adding these features in.

Rough Sketch

Here is a rough sketch of what the catapult will look like.
The baseboard and large arms will be made of construction wood bought from Lowes.
Laser-cut acrylic sheets and 3D-printed parts will make up the mounts for the servos and hinges used in the assembly.
The controls for the 3 servos will come from the potentiometers and push button switch included in our Arduino kits.

Servo Motors

The catapult will be utilizing 3 servo motors to achieve what we want. Servo 1 will control the tension in the springs setting the tension point. Servo 2 will be potentiometer controlled and will control the bar that stops the catapult arm for controling launch distance of the object. Servo 3 will be a simple button controlled servo to hold the arm down while it is under tension from the springs, when the button is pushed the servo arm will rotate 90-degrees letting go of the catapult arm and launching the projectile.

First Post

For our group project, we have decided to design and build an Arduino-controlled catapult.  The catapult will be made out of construction-grade wood, small springs, 3D-printed plastic parts (for mounting and assembling), and various parts out of our Arduino kits.  We will be able to control the release angle and velocity using the Arduino-controlled servos. Team members on this project will be Spencer Crane, Brian Ahn and Gabriella Mastrogiuseppe.