16.1 Project Proposal

Introduction

American Morse code is a simple yet powerful method of communication for transmitting messages with minimal outputs. It encodes the English alphanumeric system - consisting of 26 letters (A - Z) and 10 decimal numbers (0 - 9) - using only two symbols: a “dot” and a “dash”.

In this project, we propose constructing a mechanism that is capable of writing a  Morse Code message on a piece of paper. The device will handle both “dash” and “dot” characters for a preset phrase and use precise motion profiles to drive a marker to inscribe the corresponding symbols onto the paper.

Problem Statement

The goal of this project is to design, analyze, and construct a mechanism that uses simple driver inputs to generate a complex repeatable motion that inscribes a Morse Code message onto paper. Specifically, this should take a simple continuous input and generate a complex output.

The first component of the problem is figuring out a linkage design with a motion path that can create the “dot” and “dash” character. To achieve this, the input link to the system must take a continuous rotation, and the output link must follow a “mostly flat” motion profile. In addition, this motion profile must be able to be altered by adjusting the grounding or orientation of the mechanism to generate both a short and long stroke, resulting in the dot and dash characters, respectively. This adjustment can be performed by a separate input that simply dictates which profile is currently at play.

The second component deals with moving the writing surface to align sequential characters to be placed at appropriate distances from one another. To achieve this, an intermittent motion can be generated from the same continuous rotary input, resulting in dragging the paper along a specific distance in every rotation.

Proposed Mechanism

Our proposed mechanism consists of three integrated mechanical systems, all designed to operate on a single continuous rotary input and with minimal external controls.

The first component is a linkage system that generates the marker’s trajectory to inscribe “dot” and “dash” characters. This system must output mostly straight-line trajectories at the bottom part of its motion to ensure proper contact with the writing surface. We propose analyzing and adapting common wide motion 4-bars or a more complex walking mechanism, which have long strokes that could be used for writing. Some potential candidate mechanisms and their motions are shown below.

The second component is a switching mechanism that modifies the previous linkage system to select whether a dot or dash is inscribed. We propose using a cam follower and slider that adjusts the ground link’s position based on the linkage shape. Further analysis is necessary for this, but this custom-built component will encode a pre-programmed message as a series of characters: . . - - . - etc.

Lastly, the final component advances the paper forward after each symbol is inscribed. To achieve this, we propose a Geneva mechanism connected to a conveyor system that holds the paper. This mechanism will take a full continuous rotation and achieve intermittent linear motion of the page, aligning each subsequent character appropriately.

Scope of Work

The proposed project will follow these steps:

1. Create preliminary sketches of the mechanism design, defining expected inputs and outputs to identify potential manufacturing challenges and other considerations in proper design.

2. Evaluate the three main components of the system mathematically, using the concepts learned in lecture to ensure each system achieves the required motion and meets mobility and position criteria. Utilize programming tools when possible to confirm calculations and create plots of the expected motion profiles and linkage positions of our system.

3. Create initial CAD designs, adjusting the lengths and tolerances of every link and joint and keeping in mind manufacturability using the laser cutters and 3D printers. Design for laser cut components when possible as they’re faster and more reliable to prototype.

4. Manufacture and assemble the first hardware prototype to identify design errors, limitations, and adjustments that need to be made to the product. Take special consideration into having a smooth continuous input motion and achieving the desired output motion from the three main systems.

5. Take the lessons from the prototype and make design adjustments were needed. This may include reworking mathematical analysis, choosing different materials or a different method for assembling joints and linkage systems. Make only reasonable changes as to not change the overall design too much and slow down progress.

6. Manufacture and test a final prototype. Ensure each component meets expectations and the desired output motion profile is accomplished. Additionally, ensure there is enough contact and force to create solid characters using the marker.

7. At this point, based on timing and results, continue making informed refinements to obtain improved results as appropriate

Preliminary Design Ideas

As explained before, our design consists of three main components, each playing a crucial role in the Morse Code inscribing process.

The first and primary component is the linkage mechanism that transforms continuous input rotation from a motor into a motion profile with a mostly flat bottom trajectory. This mechanism is actuated by the second component , which shifts the ground link’s potions to alter the motion profile that contacts the page into one of two configurations. The first configuration has results in a long stroke of the marker on the page, creating a “dash”. The second configuration results in a much shorter stroke that creates a “dot”. The sketches below illustrate how the mechanisms described previously could be adjusted to accomplish this.

The final component is the Geneva mechanism that will generate intermittent motion to advance the paper after each symbol is written. A standard system, as shown before, should accomplish the desired intermittent motion, where the green pin is seen making a full rotation while the red link only moves a desired distance. This exact distance will dictate our design and will be used for a custom conveyor linkage that holds the page and drags it accordingly.