Deliverables
The Breakdown
For this project, we needed to build an animatronic based around a specific theme, which is movies. This build has to have a minimum of three actuators, include an LED event, and have a coordinated event with either two motors or a motor and LED light.
In addition to these requirements, we will need to manage a website for the project, provide mechanical sketches, and supply the pseudocode for the project. For the control system for this project, we are to use the Arduino platform that was provided.
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Spherical Shell
The spherical shell will need to house all the components, except for a LED light or two of which will be placed in the head. The idea is to have it almost a full sphere, with a slightly flattened bottom, where the wheelbase will be. The challenging part for this will be the shape itself. We plan to make the skeleton out of corrugated board, with vertical sheets of corrugated board wrapped around the skeleton. By going this route, the shell will look spherical, but will have some flat spots on it. The design itself will look similar to the globe in Figure 1.
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Retractable Arm
BB-8 has a retractable hand from his body. For this we plan on using a basic snail gear with an arm that is pushed out as the gear turns and then drops back down after a full rotation giving the illusion of the arm ejecting out and popping back in. The basic workings of a snail gear can be seen in Figure 2. This can easily be cut from 3/8” dowel rod for the arm and corrugated board for the snail cam. Since the arm is more horizontal than it is vertical, the use of a counterweight or spring would be used to help pull the arm in after it has been pushed out by the snail cam. The snail cam itself can be attached to a handwheel, which in turn would be connected to a stepper motor. This device will be located just above the center of the sphere, as this is where the arm is located on the real BB-8
Hidden Wheelbase
Unlike the actual BB-8 ours will have wheels at the bottom that allows it to roam around. We chose this as it is much less complicated than to have a rotating sphere, where the head ‘floats’ above the body. By strategically placing the wheels at the bottom of the spherical shell we should be able to give the illusion that it is spinning on just its body. To further enhance this feature, the product will only use three wheels. Two of the wheels will be operated by their own DC motor. The third wheel will be a free moving swivel wheel in the rear to help keep the product from dragging, and to increase stability. With the two motorized wheels operating independently, the turning radius can be drastically reduced. The base for the wheels will also hold the Arduino boards, helping to keep the center of gravity low.
Programming Arduino
Winter term we learned python, so most students, including all of us, have little or no Arduino experience. This will be a challenge to program what we want as we must move along with the project while learning the code. We do have the advantage of Arduino have been out for a while and it is like C++. This will help us find solutions and to troubleshoot problems we may encounter. Granted there are online YouTube videos and other codes we can look at for help; it will still be a struggle. As of now, the plan is to program the Arduino to initiate from a button trigger. Once pressed, the program should run once, causing BB-8 to move around in directions we program, while having LED lights light up according to the movements. At the end, we plan to have BB-8 stop, and stick his arm out via the snail cam controlled by a stepper motor.
Budget
Our primary build plan will utilize the equipment given to us to help minimize cost. In addition to this equipment, we would need to purchase corrugated boards for the structural material. As for mechanical hardware, we will need to acquire a handwheel for the stepper motor and a dowel rod. These two will be used for the retractable arm on BB-8. We will also need to purchase a swivel caster to act as a support for the read of the device, which can be seen in the mechanical sketches in the project gallery. For electrical, we would need to purchase additional jump wires so that the LED lighting can reach throughout the body and head of BB-8. We have a secondary build that uses the same equipment with the addition of a kit from Amazon; however, it would have been dependent on timely delivery. With the current COVID_19 situation, we would not receive the material until after the term is over. This kit would have doubled the cost; however, it would allow the lead builder to keep a the final project since we have to return the material that was provided for us from the University.
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References
[1] Amazon, “Creative Easy DIY Assembly 3D Globe World Map Geographic Sphere,” https://www.amazon.com/Creative-Paper-Globe-Geographic-Sphere/dp/B07K5PL4DY (accessed Apr. 27, 2020)
[2] V. Ryan, “The Snail / Drop Cam,” http://www.technologystudent.com/cams/snail1.htm (accessed Apr. 27, 2020)
[3] Staples, “30" x 36" Staples Corrugated Sheet, 5/Bundle (SP3036),” https://www.staples.com/Partners-Brand-Corrugated-Sheet-30-x-36-5-Bundle-SP3036/product_946714 (accessed Apr. 27, 20 20)
[4] Amazon, “nema17 Hand Wheel,” https://www.amazon.com/nema17-Stepper-Diameter-Engraving-Machine/dp/B07PN6J6ND/ref=sr_1_1?dchild=1&keywords=nema17%2BHand%2BWheel&qid=1588032891&s=industrial&sr=1-1&th=1 (accessed Apr. 27, 20 20)
[5] Home Depot, “3/8 in. x 3/8 in. x 48 in. Basswood Round Dowel,” https://www.homedepot.com/p/Woodgrain-Millwork-3-8-in-x-3-8-in-x-48-in-Basswood-Round-Dowel-10001801/206016920 (accessed Apr. 27, 20 20)
[6] Home Depot, “1-1/2 in. Soft Rubber Swivel Plate Caster with 40 lb. Load Rating,” https://www.homedepot.com/p/Everbilt-1-1-2-in-Soft-Rubber-Swivel-Plate-Caster-with-40-lb-Load-Rating-49489/203661072 (accessed Apr. 27, 20 20)
[7] Amazon, “Solderless Flexible Breadboard Jumper Wires,” https://www.amazon.com/Solderless-Flexible-Breadboard-Jumper-Arduino/dp/B083DYQBVV/ref=sr_1_7?dchild=1&keywords=jump+wires+arduino&qid=1588033154&sr=8-7 (accessed Apr. 27, 20 20)
[8] Amazon, “LAFVIN Smart Robot Car 2WD Chassis Kit,” https://www.amazon.com/gp/product/B07YCHCQNK/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 (accessed Apr. 27, 20 20)
