Mechanical Design

Robot Frame

The robot frame was entirely built of 1.5 inch Aluminum extrusion.

Catapult

The energy used to shoot the catapult arm came from the elastic bands. The elastic bands can be added or removed as needed to fine control the speed of the bean bag. Tests were conducted to see how far the catapult is able to shoot. The system is able to comfortably shoot upto 4 meters, which is a larger distance than the distance to the cornhole.

The catapult is actuated using the latching and winching mechanism.

Resetting (Winch)

The catapult is loaded using the winching mechanism where the string is connected at the bean bag holder end of the arm. As the string is reeled in, the elastic bands are tensioned (Yellow ellipse).

Launching (Latch)

The catapult arm is latched after it is pulled down all the way. Once the latch is opened, the arm launches the bean bag. This is achieved using a simple linear actuator (White Ellipse).

Bean Bag Loading

A hopper-like mechanism is used for loading the bean bag. It is a L-shaped inclined platform holding the bean bags in place until a linear actuator pushes it off the edge. The actuator is a simple servo motor and rack and pinion setup.

Movement

Chain and Sprocket

The robot has a two-wheel drive design with two driven wheels in the back and a castor ball wheel in the front. Power transmission was achieved using a simple chain and sprocket set up.

Changes from Initial Design

There were no major deviations in our design for the systems. But we did have to go through multiple iterations for the various mechanisms to find a solution that was functional and reliable.

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