Manufacturing Documentation
Introduction
The manufacturing document provides information about how to fabricate and assemble the various components of the device. For mechanincal components, this information may be in the form of CAD drawings or assembly diagrams. For electrical subsystems, schematics may be used to show how different components are connected. For software, pseudo code and other diagrams are used to show how the different parts of the software interract and how the software functions as a whole. Consequently, this page is divided into three sections:
Mechanical Components
In order to better convey the overall design of the device, SolidWorks was used to create detailed technical drawings of the device and its individual parts. The material used to create the internal parts is High Performance Composite Material produced by Z Corporation for use with their Z310 rapid prototyping device. We chose to use the rapid prototype material as opposed to plastic because of the intricacy of the parts, and the limited time span in which we have to complete this project. The material is fairly strong, and will be made stronger through the use of adding an additional hardener to the pieces once they are created.
Figure 1: SolidWorks Model of the Bottle Drum
Figure 1 represents the bottle cradle, which will open on its hinges so that the bottle may be loaded into the bottle drum. This piece is connected to the bottle drum at the hinge points, and it covers the compartment designed to hold the insulin bottles. In order to open the door, the button piece, shown in Figure 1 (red), will also be created. This piece will also be moving vertically in order to engage the syringe located below it. This is accomplished by connecting the bottle drum to two(2) shafts on which it may slide when driven by the DC motor. Figure 2 shows the pieces which will connect to the center shaft of the drum and then to the two vertical side shafts with the use of the piece also shown in Figure 2.
Figure 2: SolidWorks Model of Inner Components
In order to ensure proper alignment of the needle with the bottle being held in the drum, the two holes shown at the top of the bottle drum (Figure 1) will accept the two spikes extending out from the syringe case, shown in Figure 2. The bottom of this piece has a rectangular depression that will fit over the linear motion table and affixed using an epoxy. Also attached to the linear motion table will be the plunger holder shown in Figure 2. The two holes (red, Figure 2) shown on the plunger holder will allow the holder to be attached to the motion table by using a 0.2 inch diameter nut and bolt. This is the piece that will actually be moving vertically to allow for the dosing of the syringe.
Figure 3: Exterior of Complete Device
The complete exterior of the device is shown in Figure 3. While the interior pieces were rapid prototyped, the exterior will be made of plexiglass. The side panels will consist of ½ inch thick pieces, and the rest of the pieces will be ¼ inch thick pieces of the material. This will give us the strength and stability we need in the exterior to support our internal set-up. Finally, Figure 4 displays the final concept, with the internal pieces colored in order to better differentiate the pieces and to display their orientation.
Figure 4: Isometric View of Complete Device
Electrical Components
The overall powering of the device will consist of a DC power supply. A 12V supply will be utilized because the stepper motor requires a 12V supply. This supply will not only power the motors but also the microcontroller, interface circuit, and other digital components. Besides providing the necessary voltage, the supply must also provide adequate current to power each component. For this reason, a power supply was chosen that will provide up to 7 amperes.
The user interface consists of an optical encoder, which has a rotary shaft the user can turn clockwise or counterclockwise to increase or decrease the dose volume. The output of the encoder consists of two square waves that are 90 degrees out of phase. Cascaded to the encoder is an integrated circuit that senses the direction the encoder is turning and outputs separate pulses for clockwise and counterclockwise rotations. These pulses, in turn, are the inputs to a BCD (binary-coded decimal) counter. Clockwise pulses increment the counter, while counterclockwise pulses decrement the counter. Finally, a 7-segment display driver is used to convert the BCD output to the appropriate outputs to drive a 7-segment display. In order to transfer this information to the microcontroller, the 4-bit output of the BCD counter will be input to the controller's input pins. Finally, there will be three counter IC's, 7-segment displays drivers, and 7-segment displays because the input dosage can range from 0-100 units.
Figure 5: User Interface Block Diagram
Computer Components
The way the code is going to be integrated together is by having a main function that calls on several tasks. The reason making tasks rather then functions is because of the time it will take for some of the tasks to run. By having different tasks rather then having functions running in the main task, main will not get bogged down waiting for one of the functions to finish. Main will just tell the task what to do and it will do what was asked while the main can continue operating, which makes a more robust program. Below are links to a state table of the main function and pseudo code for the other primary functions. The reasoning for not having pseudo code for the main is because of the complexity that is involved in this process.
State Transition Table - state.xls
Pseudocode for Primary Functions - pseudocode.txt
Depending on the interactions of the user the way the device needs to do its tasks varies. Below are two use cases(diagrams and descriptions) to show the interactions that the user will go through and how it will change the actions of the device.
Figure 6: Mixed Dose Use Case Diagram
Mixed Dose Use Case Description - mixed_use_case.pdf
Figure 7: Single Dose Use Case Diagram
Single Dose Use Case Description - single_use_case.pdf