Bluetooth Board Team 59 - Luke Staunton, Oluwatobi Ijose & Nikhil Mathews ​ TA: Jacob Bryan

Introduction Objective: We are designing and implementing a system that would allow us to successfully create the impression that are spiritual forces communicating specific messages to users of a ouija board. By creating an iPhone controlled, bluetooth ouija board, we will be able to perform this illusion by allowing the board to autonomously move the towards the desired characters and make any participants feel the presence of the . A person with the designated app would be able to input a string of choice, and the planchette on the board would maneuver to spell the word, guiding the users hand with the planchette which makes the illusion much more compelling, especially to non-believers.

Background: There are many people who genuinely believe that there are actually spirits controlling what is output by a ouija board, and that there are many unseen supernatural elements to our world. Historically, ouija boards have been operated purely by the end user by phenomenon called “ideomotor effect”[1]. With the added benefit of our electromagnet, we can further influence the end users perception. We hope to play on the of these people, in order to solve the problem of a ouija board that is not actually moving on its own. While there is not an outright need for this solution, it does provide a fun trick that you can show your friends and can be much more convincing than the original ouija board.

High-level requirements: · An iPhone application that reliably sends the required data string to the microcontroller. · An electromagnet that couples with the planchette and can recognize when it has become decoupled. · A functioning electromechanical system capable of moving the electromagnet’s housing around the inside of the Ouija Board

Design Block Diagram

Physical Design:

Figure 1 (Above): Cross sectional view of physical components

Figure 2 (Above): Secondary view of physical components

Figure 3 (Above): Top down view of physical system

Figures 1-3 show the physical components critical to the overall system, except for the actual Ouija board and planchette that will sit on top. The dimensions of the containing box (gray in all three figures) is 4’’ x 16’’ x 10’’. Although not shown in their entirety in this report, we have Creo files corresponding to all of theses components. As one can see in figures 1 and 2 the component in red is the electromagnet module, which will house the electromagnet and pressure sensor and has clearance holes to allow for the axles. The components that are blue and green in figures 1 and 2 are called the “rails.” These will hold the servo motors on their extrusions. The axles are depicted in black in figures 1 and 2, although they appear to have wheels on either end, in our implementation these will be gears that will mesh into raised rack gears. Although figure 3 has a slightly different color scheming, it offers a better perspective of where the components will connect. These drawings may be subject to slight change, depending on the manufacturing constraints of the machine shop.

iPhone App Functional Overview The iPhone app will be used to control the word that appears on Ouija Board. Because this is a “” trick, the user will input a word, and the app will communicate with the bluetooth module on the board. The app will be programmed using the Swift programming language, and will have a basic UI where the user can either input an entire word, or move a joystick so the planchette follows where the user goes.

Block Requirements ● The Swift programming language to create an iPhone application that reliably sends the required data string to the microcontroller. ● Subroutine for effective communication with the bluetooth module ● Determine if the magnet is coupled. Determine where in the sequence of characters is the magnet.

Electromagnet Module Functional Overview The electromagnet module encompasses the planchette, the underlying electromagnet used to move it, a pressure sensor to help prevent decoupling of the magnet, and a BJT amplifier. The planchette would contain hidden pieces of metal, so as to attract the electromagnet that is located under the board. When a word is input in the phone app and communicated to the microcontroller via bluetooth, the electromagnet would be “magically” repositioned by two moving rails. In order to prevent decoupling, a pressure sensor will be used to gauge the difference in pressure between when the planchette is directly overhead, or decoupled. Using some threshold value, we can determine if decoupling has occurred, and move the electromagnet accordingly. Also, we will need a transistor amplifier circuit to control the amount of current going through the electromagnet, and we may need an analog to digital converter (ADC) for our pressure sensor (provided it is an analog, not a digital sensor).

Block Requirements ● Detect decoupling with separation greater than 1.5cm ● Send data from pressure sensor at least every 400 ms to microcontroller via I2C protocol ● Pressure sensor to discern when the electromagnet has been coupled (.005N or higher resolution) ● 3D printed housing for the electromagnet and pressure sensor

Motor Module: Functional overview: Each motor module will be responsible for moving one of the positioning rails to the desired position, and will act as the interface between physical goals, and the DSP control algorithm loaded onto the microcontroller. Positioning of the rail moves the electromagnet module and in turn, moves the planchette. The motor module will receive its power from the power module. The module will also take in a PWM signal from the micro to actuate the servo motor and send digital data from the analog positional sensor back to the microcontroller. As of now we are expecting to do that with a I2C ADC device connected directly to the output of the distance sensor. The physical motor will be attached to each rail and have a gear that provides torque to a driving axel. That axel will be connected to two gears that will mesh with a rack gear inserted on the inside of the box containing the system.

Block Requirements: ● Sends positional data at a higher sampling rate than 80ms back to the microcontroller via I2C protocol ● Moves the rail within +/- 1cm of the desired position when properly connected to the micro running the control algorithm ● Capable of moving the electromagnet module faster than 1 cm/s

Bluetooth Module: Functional overview: This module will be purchased (HC-05 Arduino) and act as the means of Bluetooth ​ ​ communication to the iPhone application. It will use its TX and RX ports to communicate serially with the microcontroller. It will also be powered on the same rail as the microcontroller.

Block Requirements: ● Can properly communicate with the phone application from within 5 meters

Microcontroller Module: The role of the microcontroller module is to process information received by the various modules and use that to control them. Notably, receive and process the needed string from the Bluetooth module, activate the electromagnet and determine if it is coupled, and use the prior two sets of information to set the proper feedback loop parameters.

Block Requirements: ● Process information from the Bluetooth module and use that to create a queue of characters that need to be visited ● Receive information from via I2C from the motor module and send out an adjusted control signal without interference from other subroutines ● Process the decoupling signal and have it interrupt the general control loop within a 250ms of receiving the decoupling signal ● Have a high level “sweep function” that is able to find the planchette

Risk Analysis: The potential components of our project that may jeopardize our project are mostly constrained to the mechanical build of the Ouija board. Each physical component that is even slightly misconfigured can severely impact the functionality of the planchette by either not moving it at all or by moving it an undesired amount, which could impact how the user interprets the characters and therefore destroy the illusion. Additionally, if the electromagnet gets decoupled, the latency for the search algorithm to recouple the magnet could also hinder the effect of the illusion. Another potential problem is delay and failure on the Bluetooth module because similar to the above scenario, it removes the smooth effect of gliding between letters, which can break the illusion. If the bluetooth module faults and skips a character, it may be difficult to ensure that the characters are delivered to the board in the correct order as well. A possible source of problems are processing limitations of the microcontroller. More specifically, the processor not being able to handle the Bluetooth, control loop, and the pressure sensor all frequently enough. We intend to prevent this by determining all other necessary components and restrictions before selecting the correct microcontroller.

Ethics and Safety: The core safety concern of our project is the use of 120V AC power from a wall outlet. Although we plan on purchasing the proper step-down and rectifier devices, the presence of high voltage always creates safety concerns. Crises can be prevented by being cautious of when the system is plugged in, and being diligent of which traces are carrying high voltage current. Since the motors and electromagnets are all fairly low powered and low strength, they do not pose much risk. The primary ethical concern associated with our project is the potential for it to ruin one’s reputation. Our project can be described most simply as an illusion that a supernatural being is attempting to communicate with the user. Although it may sound laughable to some, others are easily convinced that such spirits may be trying to tell them things. This proposes the risk that the project we design could be used to maliciously deceive people in such a way that harms their reputation. We’ve reviewed the IEEE guidelines for ethics[2] and although we cannot fully prevent someone from misusing our project to deceive or hurt someone’s reputation, we have considered this in our design and thus plan to make it apparent that this product is purely for entertainment purposes.

References: [1] https://www.vox.com/2016/10/29/13301590/how-ouija-boards-work-debunked-ideomotor-effect [2] https://www.ieee.org/about/corporate/governance/p7-8.html