Week 3: Nailing Down the Concepts

The final proposed idea for the Pirate Arrrcade! was presented to the instructor and met with approval. A simulation of the mechanical properties was made in AutoCAD; to view this simulation of the model in greater detail, view the following promotional video:

     

Basic model (back)

     
The basic model shows the ramps, front panel with slots, space for the vertical conveyor belt, and figure movement mechanism. The vertical conveyor belt, attached to a servo, will carry the steel balls from a hopper at the bottom of the arcade to the top of the arcade and eject them down the ramps. The figure movement controls will enable the user to jump over balls and cease motion. The initial design calls for a magnetic sensor in the figure to detect magnetic ball collision; when the magnetic sensor reads a magnetic value (that is, a ball passes within proximity of the player and therefore the sensor) and results in a negative endgame.

Figure movement mechanism

The initial figure movement mechanism is comprised of two servo motors attached to a gear which climbs up two shafts. The bracket attached to the figure will be attached to a ball bearing within the slot of the horizontal beam. This will allow for x-direction movement as the beam moves upwards. As a result, the figure will move up the ramps.

Concept drawing

The concept drawing shows possible ideas for design.  The function of the game will be worked on, and then design will be considered, but the concept drawing illustrates the aesthetic ideas behind the arcade.

The toy concept was presented to children for their input. Its appeal was graded on a scale from 1 to 5. Furthermore, during this time, changes were made to the initial design of the game.  Plans were developed to acquire raw materials and tools, research the resources available for woodworking, and make a frame by next lab meeting. The group decided to meet every other night on Floor 15 of Millennium Hall to maintain accountability and project movement. The formal design proposal was started in Week 2, and will be completed by Friday. 

Modified collision detection

The initial plan for collision detection between magnetic balls and the figure was to use a magnetic sensor on the figure.  To simplify this mechanism, the figure will have an accelerometer attached to its axle (the blue box on the model).  This accelerometer will detect when the ball collides with the figure.

The initial design for the figure movement included two servos and gears to climb up two vertical shafts.  This will be modified to two servos connected to a pulley to lift the beam with the ball bearing and figure.  The new approach will be less complicated than fitting a gear to a vertical shaft.

Below is a tentative list of materials and a rough timeline for the project.  Several systems will be developed in conjunction to expedite the process and improve testing time.

Materials and Timeline

Process	Materials	Tools and Resources
Frame Week 4	24” x 20” x 9” frame with base Backdrop Hinges (2) Handle Lock Wooden ramps Plexiglas cover	Screws/screwdrivers Drill Wood glue Machine shop
Figure movement and jump Week 5	Servo motors (2) Cables Axle, pendulum, figure* Pulley Push buttons (2) Raspberry Pi Wires Connectors Battery 5-gram servo or piston Beam with slot Ball bearing	Soldering gun Pliers Solder
Cannon balls Week 7	10 steel balls Bike chain Ball platforms* 1 servo Gear Battery 1 piston 1 “door” (barrier between hopper and conveyor)*	Soldering gun Solder
Ball Detection Week 7	Accelerometer Wires	Soldering gun Solder
Testing Weeks 7-10	Miscellaneous; as needed

* denotes 3-D printing

Finally, testing was discussed. Testing will be performed with the individual systems listed in the first column, and then with the systems integrated together as each is developed. The core of the game should be built as soon as possible to assure enough time to fix errors. More research and planning will help decided where and how to build each system.