Spin It To Win It – Portable Charger And Game Controller

The goal of the project is to improve the existing Spin IT to Win IT device so that it is more complete, durable, reliable, fun, and easy to use, requiring only a short set of instructions. The project uses a hand crank generator to turn mechanical energy into electrical energy, and store it in a battery to charge devices like mobile phones. The crank also serves as the controller for a fishing themed game that is played wirelessly via bluetooth on an android phone, adding an entertainment aspect to the otherwise mundane task of charging a battery by hand.

=Background= The previous Spin IT to Win IT team had the goal of using a hand crank generator to turn mechanical energy into electrical energy, and store it in a battery to charge small devices like cell phones. An additional goal was to use the crank as a controller for a game, which also monitored the power generated. The team created a proof of concept device, which created power with a hand crank, stored it in a battery capable of charging phones, and sent rough crank voltage data to a phone.

=Problem Definition= Our problem was that the prototype was impractical. It was bulky, heavy, fragile, had no enclosure, and lacked a working game. The use of a heavy lead-acid battery and a large bulk of loose wires, PCB’s, and breadboarded circuits made moving and setting up the device difficult.

Design Task
The objective was to improve or re-design the Spin It To Win It device so that it is more complete, durable, reliable, portable, fun, and easy to use. The device needed to use the electrical energy generated by a hand crank to charge a battery, and also serve as a controller for a wireless smart phone game.

Early in the design process, we decided our best option was to use the existing crank, and rebuild the rest of the system, with the target of fitting the remaining components into a single enclosure.

Deliverables
Hand Crank Generator (Doubles As Game Controller) A durable handheld generator was required that could reliably generate enough power to charge a battery.

DC Converters & Battery Power electronics were needed to convert the range of voltages output by the crank to a single voltage level used to charge the battery. When the voltage is lower than the desired charging voltage, a boost converter is needed to increase the voltage. When the voltage is higher than the desired level, a buck converter is needed to drop the voltage. A rechargeable battery with USB outputs and the capacity to fully charge a smart phone at least three times was required.

Communications & Data Transfer Circuitry and a microcontroller were needed to interpret signals from the crank and button, and send useful data wirelessly via Bluetooth to a smart phone.

Game & Data Display An entertaining and functional game was required to display relevant data and make the mundane task of charging fun and engaging.

Durable Packaging & Connections The packaging and connections of the device and its components needed to be much smaller, simpler, and more durable than the previous team's prototype.

Project Learning
During our initial client interviews we were given some specific minimums and guidelines. We didn’t have to limit the device to one piece, and it just had to be smaller than the previous team’s. We could re-use the crank or purchase a different model, and it was ok to add buttons to the crank. The minimum battery capacity was one, but preferably two full charges for a modern smart phone.

The background research was done primarily by going through the previous team’s files and design report, as well as tinkering with the existing project parts. Some research was done online at websites selling components we were considering using. Websites detailing DC-DC converter design and electronics project enclosure design were also important in our research.

We did some experimenting with the crank and a dummy load to see how difficult the crank was to turn under different loads. This would help us get a better expectation of charging performance under varying conditions. The input impedance of the system would determine how fast we can crank, and how difficult turning the crank would be.

We brainstormed ideas based on our requirements and initial research as to how to implement the different parts of our system, and it’s overall design. We considered enclosing the entire project in the crank, or dividing it up into two or three enclosures, made of metal, wood or plastic. We considered whether to use a buck converter as well as a boost converter, or just use a single buck-boost converter. We had the option of buying an off-the-shelf model, or designing and building one ourselves. There were also almost limitless options for the microcontroller, each with advantages and disadvantages. As for the game design, we could do almost anything, with the main limitation being the number of possible inputs. There were many battery solutions available, but only a handful that fit our requirements closely.

Design Considerations
Our design decisions were made while taking a number of factors into consideration. These factors were different for each technical role, but generally consisted of the following: Size, Practicality, Durability, Reliability, Cost, Availability, Capacity, Complexity, Ease of use, Entertainment value, and how well it met team goals and existing specifications.

To objectively weigh and compare the different possible solutions to each project subsystem, a decision matrix was created for each. The decision matrices were used to score different solutions based on important criteria related to the subsystem, system as a whole, project scope, and overall goals. Each criterion is weighted, with the highest number being most important. The different options are then scored based on how well they meet the criteria from 1 to 5, with 5 being the best score. The score and weight for each option and criterion are multiplied, and the total scores for each option added up. The option with the highest overall score is chosen as the solution we implement.

Microcontroller Five options for microcontroller and Bluetooth solutions were considered. Using the existing setup, improving the existing setup, a Teensy microcontroller with separate bluetooth module, using a Firebeetle with integrated bluetooth, or using a beetle with integrated bluetooth. The criterion used were meeting team goals, within operational parameters, size, design complexity, and cost. After scoring the solutions, the Beetle ESP32 microcontroller was chosen. Microcontroller Decision Matrix

Buck-Boost Converter Three options for the buck-boost converter were considered. Designing a buck-boost, buying an off-the-shelf model, or using the existing converters. The criterion used were size, cost, and design complexity. After scoring the solutions, the option to buy an off the shelf model was chosen. Buck-Boost Decision Matrix

Enclosure Material Four options for the enclosure material were considered. Wood, plastic, 3D printing, and metal. The criterion used were cost, durability, aesthetic, and weight. After scoring the solutions, plastic was chosen. Enclosure Material Decision Matrix

Project Layout Four options were considered for the prototype layout. All components except battery within the crank, Buck-boost and microcontroller in enclosure with separate battery, Buck-boost and microcontroller in enclosure with battery in the crank, or all components except crank in one enclosure. Criterion were size, user friendly, design complexity, cost, and durability. After scoring the solutions, all component in one enclosure separate from the crank was chosen. Project Layout Decision Matrix

Game Five game ideas were considered, some based on existing games. The criterion used were fun, complexity, final goal, game UI, and innovativeness. After scoring the solutions, a fishing style game was chosen. Game Decision Matrix

=Specifications= System: Phone: Android OS Game Style: Fishing Wireless Protocol: Bluetooth Low Energy 4.2 Average Power Produced At Steady State: 7.14W Average Charging Current At Steady State: 1.4A DC System Charging Voltage: 5.1V DC Typical Speed While Charging System: 35 - 45 RPM Total System Weight: 2lb 6oz (1088g) Dimensions of System (Not Including Crank): 157mm x 94mm x 29mm

Generator: Model: Huaban Hand Crank Generator Rated Power: 30W Output Voltage: 0-28V DC Output Current: 0-2A Max Current: 3A Weight: 616g Dimensions: 106mm x 64mm x 39mm Maximum Rated Speed: 120 RPM

Buck-Boost Converter: Model: DROK 200234 Rated Power: 30W Input Voltage: 5-30V DC Input Current: Up to 5A Output Voltage: Adjusted to 5.1V DC Output Current: 3A Maximum Switching Frequency: 180KHZ Dimensions: 68mm x 29mm x 21mm

Battery: Model: Vancely K111 Capacity: 10,000 mAh Cell Type: Lithium Ion Input Voltage: 5V DC Input Current: 2.1A Output Voltage: 5V DC Output Current: 2.4A X 2 Dimensions: 124mm x 67mm x 15mm

Sampling Circuit: Operating Voltage: 3.63V - 4.17V (Directly from battery cell) Current Draw During Operation: 4.4mA Average Power Consumed: 18mW Voltage Divider Resistor Values: 963kOhm & 74.8kOhm Biasing Diodes: 2x 1N4733A In Series Op-Amp Buffer: AD817AN

Microcontroller: Model: Beetle ESP32 Operating Voltage: 3.63V - 4.17V (Directly from battery cell) Current Draw During Operation: 68mA Average Power Consumed: 272mW Programming Via Arduino IDE

=Circuit Diagrams=

=Final Design= The final project design consists of the crank generator connected to the device enclosure with a 4 foot cord, and weighing a total of 1.09kg. The enclosure is made of a durable black ABS plastic, and contains the battery, buck-boost converter, microcontroller, and sampling circuitry. The device is charged by turning the crank in either direction, or via the micro USB input on the front. There are two USB output ports on the device capable of powering or charging USB devices up to 2.4A. Pressing the button on the side activates the USB ports, and pressing twice disables them. The front panel also contains battery status indicator LED’s to show the charging status and current battery charge. Each of the 4 LED’s indicates 25% charge. There is an ON/OFF switch on the side which powers the microcontroller and sampling circuitry. At a maintainable steady speed, the battery is charged at 5.1V DC and 1.4A.

The game is opened on an Android phone. Upon launching, you are brought to a home screen, where the game automatically searches for and connects to the beetle microcontroller. The Bluetooth doesn’t need manually paired, the game handles the entire connection process. Pressing start begins the game, and at this point, the user presses the button on the crank to release the hook. The hook drops to the bottom, where a fish will eventually be caught. Once a fish is on the hook, the crank can be turned to reel it in. The goal is to reach the top without touching any of the sharks. The speed of the crank determines how fast the fish is reeled in. The voltage output by the crank is displayed in the upper left corner along with the score. Reeling a fish all the way to the top earns the player 10 points, and the opportunity to try again for more points. If the fish touches a shark, the game is over, and the user can try again or quit.

=Validation= All aspects of the game and system work as they were designed to, and the team goals were reached. The final device is more complete, durable, reliable, fun, and easy to use. A demonstration video showing the system in operation can be viewed HERE.

=Final Game Appearance=

=Evaluation= The final product met all of our original goals and performed to our expectations. The device was more complete, durable, reliable, fun, and easy to use than the previous team's design. The crank charges the battery at a rate that is acceptable for a human-powered device of its size, and only about 25% slower than charging the battery via USB. The game elements and movements are well calibrated to provide a fun challenge to the player, without being overly simple.

Our main challenges were often not of a technical nature, but in sourcing parts and building a prototype during a pandemic, when businesses and supply chains are closed or strained. The technical challenges we did face primarily centered on the battery charge control circuit built into the battery bank. On multiple occasions, the charge control integrated circuit failed due to an over-voltage situation caused by turning the crank from a dead stop too quickly. The likelihood of this situation was greatly reduced by adding a capacitor to the output node of the buck-boost converter to smooth out voltage spikes.

Suggested future improvements to the device would be adding more effective protection on the buck-boost output node. There may be more effective protection circuitry designs or methods that could increase the reliability. A different buck-boost converter may also provide faster voltage regulation than the model we used.

Additions and upgrades to the game such as adding different fish, more levels, or more hazards would make the game more engaging and entertaining. Additional buttons could also be added to the crank to control more features. The best upgrade might be to add a second crank so the game is multiplayer. The added competition would be fun, as well as doubling the charging capacity.

=Team Members=

=Additional Documentation=

Demonstration Video

Project Demonstration Video

Final Design Report

Design Report

Project Schedule

Spring Schedule Rev. Feb 25, 2020

Spring Schedule Rev. April 21, 2020

Fall Schedule Rev. September 15, 2020

Fall Schedule Rev. December 8, 2020

Budget

Final Project Budget

Action Items

Final Action Item Report December 8, 2020

Team Meeting Minutes

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