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Senior Design

Phase 4

Microplate Loading System

Team Siemens

Maxime Dempah, Paul Masullo, Daniel McCarthy, Leah Putman, Daniel Russakow

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Contents

Project Details ...................................................................................................................................... 1 Final Deliverables ............................................................................................................................ 1

Benchmarking and Previous Concepts ........................................................................................ 1 Final Concept ....................................................................................................................................... 2

Door ................................................................................................................................................. 2 Loading Mechanism....................................................................................................................... 3 Transport (Not in Prototype) ........................................................................................................ 3

Electronics and Programming ...................................................................................................... 3 Operation ........................................................................................................................................ 4 Overall System View ...................................................................................................................... 4

Performance Validation ....................................................................................................................... 5 Testing Calibration ........................................................................................................................ 6

System Testing ................................................................................................................................ 6 Time of Operation ............................................................................................................................ 7

Accuracy of the System .................................................................................................................... 7 Cross-Contamination Testing .......................................................................................................... 8

Maintenance of the MicroScan Testing Environment ...................................................................... 8 Reliability ......................................................................................................................................... 8

Cost .................................................................................................................................................. 9 Path Forward ........................................................................................................................................ 9 Appendix ............................................................................................................................................ 11

Reliability Report ......................................................................................................................... 12 Figure 5: Sensor Location Diagram .............................................................................................. 16 Table 1: Input-Output Designations............................................................................................... 17

Figure 5: Process Flow Chart ......................................................................................................... 18

Table 2: Transportation System Evaluation ................................................................................... 19 Table 3: Pusher Evaluation ............................................................................................................ 20 Table 5: Initial corresponding Wants and Metrics ......................................................................... 21

Table 4: Door System Evaluation ................................................................................................... 21

Table 6 - Project Progress .............................................................................................................. 22

Table 7: Prototype Parts, Materials, and Cost ................................................................................ 24

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Project Details

Siemens is a worldwide supplier of medical and healthcare technology. One of their products includes the MicroScan WalkAway 96 Plus (MicroScan herein), which is used in hospitals to test microbiology samples from patients which are held in microplates. A microplate is a small container with 96 milliliter-sized wells for holding small amounts of microbiological content.

Currently, microplate filling and loading into the MicroScan are done manually. After pipetting a patient’s material for testing into a microplate, the operator needs to individually load the microplate into a tower which is then set into the MicroScan. Siemens, however, is in development of a station for automated microplate filling, (MicroFiller herein). Yet, without any other machinery, the microplates would still need to be loaded into the MicroScan by hand. The company has asked the design team to develop a method and prototype for automated loading of these microplates into the MicroScan.

Specifically, Siemens has asked for: i.) A transport system concept to deliver two microplates from MicroFiller to the MicroScan. ii.) A prototyped loading mechanism to load the bottom slot of a MicroScan tower. iii.) A prototyped access door to the back of the MicroScan. Automating the filling, transport and loading processes increases time efficiency, eliminates human

error and reduces exposure to germs and drugs commonly found in microbiology labs. Siemens plans on using this overall setup to rekindle market interest in the MicroScan and increase the potential value of the MicroFiller to customers.

Figures 1 and 2: The microplate MicroFiller (left) and MicroScan WalkAway 96 Plus (right)

Final Deliverables - Functional, light- tight access door to the back of the MicroScan - Functional mechanism for transporting microplates through the access door and into MicroScan

tower - Conceptual design of a transportation system from the MicroFiller(not yet commercially available)

to the MicroScan - An initial reliability report to develop a total system with a lifetime of seven-years continuous use. - A quality animation displaying proof of concept.

Benchmarking and Previous Concepts

To arrive with a prototype capable of accomplishing these tasks, the team performed extensive

benchmarking, brainstorming and calculations. Benchmarking included looking at numerous consumer

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products which perform pick and place motions, transportation of an item and various door styles. Cost

and unnecessary complexity proved to be the biggest factor in limiting the basis of our design technology.

Additionally, Siemens appreciated an effort to utilize technology similar to what is currently in use in any of

their products. From this information, the team generated concepts for three subsystems: a door, a

loading mechanism and a transportation system. Door concepts included garage door style door, linear

actuator driven door, a four bar link driven door and a direct drive door. Based on metrics derived from the

wants given and the driving metrics of size, weight, and speed the direct drive door was chosen. Loading

mechanism concepts included several passive concepts, a four bar, and an active gripping mechanism. The

active gripping mechanism was chosen for its positional control and ability to work best to prevent cross-

contamination. The team chose a THK belt actuator as the best choice for Siemens in the next phase of

production from among magnetic tracks, rack and pinion, ball screw and conveyor belt options due to its

high positional tolerance, service life, and simplicity.

Final Concept After performing the necessary calculations and going through several design iterations, the

following concepts were prototyped and tested for future use by Siemens.

Door

The concept selected is a

simple, actively-controlled door

mechanism. A stepper motor has

been directly attached to the hinge

and door via shaft coupling. As the

shaft on the motor turns, the door

is rotated at the same speed. The

door is very lightweight so only an

inexpensive, low-torque motor is

required for quick movement. Mounted bearings ensure smooth operation of the door. Insulation has

been added on the inside of the door to maintain temperature conditions inside the MicroScan. The

thermal insulation has been attached to the inside of the door, as well as sealing around the opening in the

cover of the MicroScan. All components are built on a mounting bracket so that the mechanism can easily

be installed onto the cover as well.

Figure 3: Door System Prototype and Model

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Figure 4 – Loading Arm Prototype and Model

Loading Mechanism

An actively-controlled pusher mechanism has been developed to maintain hold of the titer plate

and cover before moving the titer plate into the MicroScan tower. The mechanism involves using a

miniature linear actuator located on the top part of the grip to pull up the bottom part, on which the

microplate is resting. The action is much like a palette pickup by a forklift. This movement sandwiches the

microplate and cover in-between the grips. Then a rack and pinion, geared-stepper motor system (7.2:1) is

required for accurate placement of titer plate within the tower. When the titer plate has been located

within the tower, the actuator releases the microplate by extending and the geared stepper retracts the

grip out of the MicroScan, returning to a home position and for ready its next microplate. The rack length is

dependent upon the distance the pusher is away from the tower, which is constrained by the door

movement, grip and transportation mechanism dimensions, but it can be programmed for a variable

distances. A second guide shaft has been added to constrain rotational motion of the grip. Linear bearings

have been added to the rack and guide shaft to ensure smooth operation.

Transport

The THKGL15N transport concept uses a belt and pulley system inside of a track to pull the cart through specified positions. Positions are controlled by specifying a step count for the motor or by placing sensors along the track and using a feedback system. Travel speeds can cover the necessary range with modest accelerations, which prevent cross contamination in the microplates. This system offers simplicity, compatibility with current technology, and also exceeds continuous life standards Siemens requires in a lightweight package. For this prototype, a

manual slide functions as the transport system. A designed cart originally meant for use on the THK system has been modified for function on the manual slide.

Electronics and Programming

In order to automate the loading, the team programmed the miniature linear actuator and stepper motors as required for use with Siemens custom CAN boards and motor control programs. Wiring has been directed away from moving parts, and an e-chain has been added to the loading to avoid loose or pinching cables of the linear actuator between the grip and geared-stepper motor block. The prototype includes sensors for programming logic and is constrained to confirming the position of the access door (open or closed) and the loading mechanism (at home position next to the motor block) or in loading process.

Figure 2: THK GL15N Transportation Concept

(Not in prototype)

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Programming of the actual automation is discussed later.

Operation

The MicroFiller, when completed, will initially load two microplates onto the transportation system. Hence, the design team decided to start the operation cycle at this point. Two microplates will be placed onto the designed transportation cart and the following sequence will load them into the MicroScan:

1.) When microplates are in position on the transportation cart, the door will open. 2.) The transportation system moves cart in position aligned with door and the loading arm 3.) The loading arm grip opens; the loading arm moves into position to pick up the (first) microplate. 4.) The grip is closed; microplate is lifted from the cart and the lid is secured by the top grip. 5.) The MicroScan ensures that there is an empty bottom slot in the tower intended for loading. 6.) The loading arm moves the grip into the MicroScan, inserting the plate into empty tower slot. 7.) The grip opens to release the microplate; the loading arm returns to its original position (home). 8.) The transportation cart is repositioned for loading of the second plate. 9.) Steps 3 through 7 are repeated. 10.) The transportation cart returns to the MicroFiller in the ready position for two more microplates. 11.) The MicroScan access door is closed.

To account for using a manual transportation, the team added pauses at the proper steps and then

continued automatic motion by clicking a dialogue window button. Videos have been recorded from

external and internal perspectives for demonstration.

Overall System View

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Performance Validation After determining a project scope, the design team worked with Siemens to cultivate specific wants

of the overall system, as well as develop target metrics of the sub-systems. As the basis for concept generation and selection, these wants are explained in the context of the prototype and validated by passing a series of tests.

Wants Validation

Microplate Transportation: The system should provide a method of moving two microplates from the MicroFiller to the MicroScan via a conceptualized transport system. The design team has determined an existing product which will suit this want, providing repeatable microplate displacement with an accuracy of 0.00315 in. The THK LM Actuator Model GL15N has been designed well within the 0.04-in. window required for the positional tolerance of the microplate inside the MicroScan tower. This high positional accuracy relaxes the required tolerances in the designed system’s structural frame.

Full Automation: The prototype currently requires an operator to replace the role of the MicroFiller, in development, which will place two microplates onto the transportation system cart. After this, however, an operator can simply run a program will in turn output mechanical motion without any further operator involvement. Once implemented with MicroFiller and transportation system, there will be no need for operator intervention unless an error or failure has occurred. After microplate loading, all subsystems will return to their initial positions, ready for their next iteration.

RoHS Compliance: Siemens adheres to Restrictions of Hazardous Substances standards and approved parts to guarantee customer safety. The design team has kept these restrictions in mind when searching for and selecting parts and their providers to ease the transition from prototype to production.

Reduced Size and Weight: With the size constraints of medical testing laboratories in mind, all subsystems have been designed within the target dimensions discussed with Siemens, where the system will remain within the width of the MicroScan and a 2.5 ft. depth behind it. Small, lightweight components have been utilized to keep the total system weight under 50 lbs. allowing for reduced shipping costs, handling, and installation possible by a single person.

Use of English Measurements: Even with the necessary use of some metric-based warehouse components, the team designed and specified dimensions such that Standard US hardware and engineering drawing measurements are primarily used. This means any Siemens servicing technician needs fewer tools to install or repair the system.

Adjustable Height: Since each installation environment is different, the system frame has been manufactured with adjustable feet for height adjustability. This allows the system to compensate for unlevel surfaces while maintaining proper positioning between the MicroFillerand MicroScan, as well as keeping alignment of the loading system and the MicroScan.

Maintaining the MicroScan Testing Environment: The system must preserve testing conditions within the MicroScan during its operation. The access door designed implements thermal insulation and sealing to prevent light contamination and reduce heat loss. Quick operation of the access door and loading arm also means less loss of testing time.

Prevention of Cross-Contamination: Material from one well in a microplate must not touch material in another well. The system design has accounted for the possibility of cross-contamination of testing samples in the microplate between wells. This should also be considered through testing to ensure that the system will be reliable for a lifetime of 7 years.

Although not included in the prototype, eventual implementation of a plastic, molded safety shield will protect users from moving parts and protect the mechanisms themselves from accidental bumping and potential misalignment. The team will check electromechanical parts for function and safety before implementing them into the assemblies. Size and weight metrics will be checked by measuring and weighing as appropriate.

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While performance validation of each subsystem is still valuable, it is more imperative to test performance of the entire system together. Design features such as the structural frame of the transportation system and the loading arm, as well as sensor positioning and control board programming for automated motion, are dependent upon the subsystem designs. It is safe to say that without these components the total system would not satisfy all of Siemens’ wants. However, it is not safe to say that if all target metrics for the subsystems are met then the system will perform properly. Therefore, for the success of this project, tests of performance validation will involve the whole system and aren’t bound to analysis of a single target metric. If enough time remains after total system performance tests, the individual subsystems will be scrutinized to ensure all target metrics have been met as well. Testing Calibration

In order to perform all our tests, our full prototype needed to be programmed and be fully

automated. A LabView-based program (Motor Manager), which is used to interface a computer with

Siemens control boards, calibrates and tweaks the system to meet the expected target values. The first

part of the programming was establishing a relation between the motors and the various sensors mounted

on the system. The two home sensors were set up (sensor 1 connected to the gripper base, and sensor 2

on the carousel of the MicroScan. The home sensors are used to provide a high repeatability and accuracy

when sending the mechanism back to its starting point at the end of a full cycle (sensor 1: gripper ready to

load a plate back in the base, sensor 2: door closed), as well as program logic (confirmation that the proper

parts have been moved. The second part of the programming was to define the number of steps that each

motor connected would need in order to reach their proper working positions. This part was done by

manually setting each system in its final position and reading the encoder data. Once the positions were

found, the full loading of a microplate was done by manually entering the step counts for each part of the

cycle. To provide a repeatable motion, every step of the cycle was programmed into a uniquely. Using this

process also allowed the team to troubleshoot every step of the cycle instead of having to run a full cycle.

The final part was then to create a full sequence, which means combining all the steps of the loading cycle

into one command. It is very important to note that many more sensors will be needed to ensure the

reliability of future implementation of a transportation system and filling station.

System Testing

After calibration, the team performed testing to ensure constraints and wants were met. Table 1

below shows a summary of these goals, their metrics and the results with a full explanation of test

procedure and results analysis following.

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Table 1: Wants, Constraints and Test Results

Wants/Constraints Results Metrics

Cover must remain on plate yes y/n

No cross contamination yes y/n

Temperature/ Humidity control

Yes

Yes

<21s

Insulation?

Sealed? (Light test)

System cycle in under 30 seconds

Automated loading into MicroScan 2 Number of operator inputs: <10

Accompanying high quality animation yes y/n

Adhere to RoHS environment standards Yes Sealed to IP61: dust and water resistant

Interfacing with filler machine (concept) Yes y/n

Small transporter/loader size

4”x6” Area of existing machines, max.: 2 ft

Total weight under 50 lbs.

Maximum size of door opening: 4” x 7.5”

English hardware implementation Yes y/n

Adjustable transporter/loader height Yes Include leveling feet: y/n

Low cost < $5000 Maximum cost: $10,000

Time of Operation

Objective of Test: Determine whether a microplate can be loaded into the MicroScan in less than or equal to 30 seconds. Description of Test: The design team will test operation time for the following processes in their proper sequence: door opening and closing, microplate transportation from the starting point to the MicroScan, and microplate loading from the cart position into the tower. A simple stopwatch should suffice for recording. Experimental Plan: The system will run multiple times under normal conditions and time will be measured from the starting point on the manual slide to the point when all components have returned to home position after a microplate has been loaded. Motor speeds for the MicroScan access door and the loading arm will be adjusted if necessary. Since the cart requires manual movement, there will be some standard error in the average cycle time. Data Collection and Analysis: Readouts from the automation programming average 20.14 seconds per microplate loading, which is under the 30-second goal. Standard deviation is 1.22 seconds.

Accuracy of the System

Objective of Test: Ensure that a microplate is properly loaded into the MicroScan. Description of Test: Placement of the microplate with its cover through the access door of the MicroScan and properly into the loading tower will be checked by over multiple trials. This will also confirm:

a) Positional accuracy of the loading arm depth within 0.3 in. b) Full insertion of the microplate into the MicroScan. c) Cart control within a 0.04 in. tolerance window between the microplate and tower sides.

Experimental Plan: The system will run multiple times. A success/failure criterion will be designated after each run dependent upon the achievement of proper microplate loading. Data Collection and Analysis: Failure analysis and system adjustment is required for any unsuccessful microplate loading. Eventually, the system was run 10 times consecutively without failure.

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Cross-Contamination Testing

Objective of Test: Ensure no cross-contamination of testing samples within a microplate to prevent loss of test integrity within the MicroScan. Description of Test: To establish reliability and guarantee that no samples are cross-contaminated between wells of the microplate, the team will conduct multiple dye crossover tests. The wells of microplate will be filled alternating between three drops of water and three drops of dye will be placed in alternating wells. Inspection of the microplate will occur at three points during operation:

a) Cart arrival at MicroScan by the transportation system. b) Plate pick-up by the loading arm. c) Microplate loading into the MicroScan tower.

Experimental Plan: Visual inspection is required to determine success or failure after each point. Data Collection and Analysis: Failure analysis is required if any cross contamination occurs. The system was run 10 times without cross-contamination.

Maintenance of the MicroScan Testing Environment

Objective of Test: Ensure the MicroScan will be able to maintain its microplate incubation conditions for testing integrity. Description of Test: This test involves evaluating the sealing and insulation of the MicroScan access door. Incubation conditions of the MicroScan involve a dark, humid, and warm atmosphere, similar to that inside a human body. The designed door system needs to ensure that the MicroScan can maintain these conditions. The access door has been design with a light seal and thermal insulation. To test for a light contamination when the door is closed, the fully assembled prototype will be placed in a room with all ambient lights turned off. An above-natural intensity light source will be put against the door seal and a light diode will be put on the other side of the seal to determine the amount of light able to leak through the seal. Unfortunately, thermal testing is not possible at this point in time. Given only the frame components of the machine, creation of incubation temperatures requires an operating MicroScan. If an operating MicroScan were provided, a thermocouple could be placed on the outside of the door and compared to the surface temperature on other outside areas of the MicroScan. Experimental Plan: Experimental variables include the intensity of light used, as well as the sensitivity of the light diode for data collection. Data Collection and Analysis: Data collection will is based upon readouts from the light diode. Testing showed no readings above calibrated levels. This ensures no light leaking through the access door.

Reliability

A full reliability study under Siemens’ standards exceeds the time constraints of this project. The design

team suggests a Failure Modes & Effects Analysis. A full explanation and analysis of the appropriate testing

is available in the Appendix.

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Cost

The total cost of the prototype is $4,420, well under the initial budget of $10,000. A more

complete breakdown of this cost follows.

Given this general cost, a few notes should be considered when comparing it to the detailed cost

breakdown in the Appendix (Table 7).

1.) This price does not include cost of the electronics such as the wiring, control boards, computer

hardware or software, which were all provided by Siemens.

2.) This cost is an estimate if all parts needed to be ordered and manufactured. Many of the major

components of the built prototype were actually obtained directly from the Siemens warehouse,

and hence no actual cost to the company was incurred.

3.) This graph quotes the suggested THK transportation system when the system used for the

prototype cost less than $100.

4.) This cost does not include machinist costs for part fabrication.

5.) A rate for labor has not been factored into this chart. The design team estimates that at least 300

total man-hours of labor went into the design and fabrication of this prototype.

Path Forward

If Siemens intends to eventually bring this system to market with the filling station, many

adjustments and modifications need to be made to the current prototype. Firstly, a transportation system

capable of automation needs to be manufactured and integrated into the design of the MicroFiller as well

as the loading arm and MicroScan. The design team has suggested a pre-developed system from THK which

could be adapted for Siemens’ needs.

Secondly, Siemens needs to develop a way to index the loaded microplates. Currently, the loading

arm will only fill the bottom slot of a tower meant to hold 12 microplates. While the internal elevator of

the MicroScan is able to move around the microplates, the covers cannot be taken out unless done

manually. Hence, if the current design were implemented, the loading system would only be capable of

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inserting 8 microplates, as there are 8 towers within the MicroScan. If the loading arm could move

vertically and the access door be modified for microplate loading of any tower slot, the loading arm could

index the microplates instead of making adjustments to the MicroScan itself.

Thirdly, further reliability testing and analysis is required to guarantee the product’s lifetime of 7

years without servicing. A fully integrated system involves many different components and therefore is

susceptible to many different failure modes. Hence, the sooner quality control and reliability testing are

applied to subsystems, the easier testing becomes further down the production process.

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Appendix

Reliability Report Figure 4: Sensor Locations Table 1: Input-Output Designations Figure 5: Process Flow Chart Table 2: Transportation System Evaluation Table 3: Pusher System Evaluation Table 4: Door System Evaluation Table 5: Initial corresponding Wants and Metric Table 6: Project Plan Table 7: Prototype System Parts, Materials, and Cost Figure 6: Door Drawing Package Figure 7: Pusher Drawings Package

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Reliability Report

Failure Modes & Effects Analysis: Although there are multiple types of failure analysis, this report will focus

on a FMEA, or failure modes and effects analysis. This analysis focuses on the identification and

assessment of individual components. More specifically, this is a bottom-up, hardware and functional

approach. Not only will individual components be evaluated, but any loss of function or feature will also be

brainstormed.

Most relevant to this project, failure will be defined as any loss that interrupts the continuity of the

transportation/loading process. More generally, failure is not meeting target expectations of the plate

successfully being loading into the MicroScan. As actual testing is performed, ratings for how difficult

detection of failure was and how often each mode failed can be given. Then a Risk Priority Number (RPN)

can be assigned to each component:

Severity ratings are based upon the difficulty of mechanically repairing the system after a mode of failure.

Ideally, severity ratings should also be made with other difficulties encountered, such as expense and

machine downtime. Modes of failure with the highest RPN values should be addressed first to most

significantly improve reliability. A chart addressing individual part analysis is presented on the following

page.

The highest RPN values were calculated in the rack & pinion, the electrical wiring, and the

computer programming & control board. The probabilities in the calculations were estimated based on the

problems encountered and resolved during assembly and testing of the overall system. Please review the

chart on the next page for more specifics.

Failure Testing and Interpretation of Data

Siemens suggests using a Reliability Growth analysis for actual testing. Analysis includes the

collection, modeling, and interpretation of data from development testing. The prototyped machine is run

under a single acceleration factor until failure. The failure is recorded, fixed, and then tested again until the

next failure of any kind. This cycle is continued until sufficient data has been generated, which is

determined by the engineers. Actual develop testing spans a long period of time and is beyond the time

constraints given in Senior Design. However, should the prototype be developed further, failure testing

should be done early in the development process to avoid heavy setbacks down the line, such as re-

engineering manufactured parts or expensive repair.

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Part Description Failure Modes Effects Safeguards Actions Severity

Rating

(1-10)

Prob. of

Occurrence

(1-10)

Prob. Not

Detecting

(1-10)

RPN Corrective

Action

Cart Transports plate

from fi l l ing machine

Incomplete

travel

Plate incapable of loading

into MicroScan

Diagnostic communications

check prior to plate

transportation

Error message i f

diagnostics

check fa i l s

3 3 1 9 Cal ibration

of

transportatiMisa l ignment

w.r.t. loading

arm

Cart interferes with loading

arm travel

Diagnostic run of system

prior to plate

transportation

Acceptable as i s

Linear

Actuator

Actuates grip

mechanism on the

loading arm

Incomplete

actuation

Loading arm incapable of

gripping or releas ing plate

Diagnostic communications

check prior to plate

transportation

Error message i f

diagnostics

check fa i l s

4 1 1 4 Clear path of

travel

Diagnostic run of system

prior to plate

Acceptable as i s Replace

component

Geared

Stepper

Provide motion to

insert or retract grip

from MicroScan

Incomplete

travel

Plate not loaded properly

into MicroScan

Diagnostic communications

check prior to plate

transportation

Error message i f

diagnostics

check fa i l s

4 1 1 4 Clear path of

travel

Imprecise

displacement

Grip cannot be retracted Diagnostic run of system

prior to plate

transportation

Acceptable as i s Replace

component

Rack &

Pinion

Transforms rotary

motion of s tepper to

Misa l ignment

of gear

Excess ive gear wear Visual inspection Acceptable as i s 5 2 5 50 Al ign

gearing

Gear locking or vibration &

non-smoot motion

Diagnostic run of system

prior to plate

Replace

component

Shaft

Bearings

Ensures smooth

motion of loading

Improper or

excess ive

Excess ive wear & Increased

Slop

Visual inspection Acceptable as i s 4 1 1 4 Replace

component

Inefficient motion Diagnostic run of system

prior to plate

Door

Stepper

Opens and closes

MicroScan access

door

Incomplete

travel

Plate not loaded properly

into MicroScan

Diagnostic communications

check prior to plate

transportation

Error message i f

diagnostics

check fa i l s

4 1 1 4 Clear path of

travel

Testing conditions cannot

be mainta ined within

MicroScan

Diagnostic run of system

prior to plate

transportation

Acceptable as i s Replace

component

Door Seal Ensures testing

conditions in

MicroScan when

closed

Seal fa l l s off

Deterioration

of sea l

Testing conditions cannot

be mainta ined within

MicroScan

Visual inspection Acceptable as i s 2 3 5 30 Replace

component

Electrica l

Wiring

Provides connection

between system

program and parts

Loose

connection

Communication lost to

system parts

Diagnostic communications

check prior to plate

transportation

Error message i f

diagnostics

check fa i l s

3 4 4 48 Replace

component

Faulty wire Acceptable as i s

Computer

Program

Provides

communication to

automate motors

Buggy

software,

incorrect

programming

Mechanisms do not function

properly or at a l l

Diagnostic communications

check prior to plate

transportation

Acceptable as i s 8 7 1 56 Debug,

reprogram

& Control

Board

Board fa i lure Diagnostic run of system

prior to plate

transportation

Replace

board

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For this project’s acceleration factor, it would be ideal to increase the frequency of loads by the system.

Lifetime is determined by the time required to transport microplates from the MicroFiller to the MicroScan.

Hence by increasing the number of loads over time, the system’s lifetime is accelerated. In the simplest sense,

the test also demonstrates system function.

Figure 3 – Source: http://www.weibull.com/hotwire/issue21/ht21_1.gif Reliability engineers like to model failure rate by a “Bathtub Curve” displayed in Figure 1. Often, there

are frequent failures in the early stages of testing, known as infant mortality, and those devices or designs are

rejected. As testing continues and adjustments are made, a near constant failure rates span a majority of the

devices lifetime. The failure rate increases at the natural end of a device’s lifespan, where the most frequent

failure modes are simply due to wear-out. These individual devices are also rejected from further testing. The

constant failure rate in the middle section is can also be considered the mean failures per year (MFPY).

Siemens strives for their products to last 7 years of use before required servicing. The Bathtub Curve

should therefore span a 14 year period, which places a 7-year mark in the middle of the graph. Statistically, the

7-year lifespan should have a low failure rate with confidence in a similar rate a year before or after. Ideally, this

constant MFPY should be as near to zero as possible.*

For Reliability Growth analysis, engineers also like to plot Reliability Sequential Test Plans. An example is

displayed below:

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Figure 4 – Source: http://upload.wikimedia.org/wikipedia/en/4/41/Reliability_sequential_test_plan.png Starting from the origin, the engineer is able to plot a line of the number of failures over time or number

of cycles. When the failure rate is too high, the line crosses into the area of rejection and changes need to be

made. However, with enough testing, the mechanism can also cross over to the accepted region, where the

device can be deemed reliable. The engineer determines the slope of the threshold lines (for Siemens, usually

around 0.1 for both).

*Other Reliability Considerations

With any design, there are tradeoffs for wanted functionality, including reliability. These tradeoffs need

to be considered before future resource investment is made into the project. As efforts are made to increase

reliability, the machine’s cost of production typically increases as well. At some point, the device may cost too

much to redesign or to sell. Additionally, changes take time. Projected deadlines need to be weighed in

decision making so that the overall project completed in a timely manner. Lastly, it should be noted that at

some point modifications make little difference in the target value. For example, the MFPY of a device is 0.5,

where 0 is ideal. Making a modification is predicted to bring the value down to 0.2 and a further change

decreases it to 0.1. However, the first modification only took a month while the second spanned six months.

Engineers need to determine whether the second change is worthwhile. Such factors need to be evaluated

before further testing is completed.

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Figure 5: Sensor Location Diagram

Flag or slot sensors have a small light beam between its ends. When an object, “flag”, breaks the beam

within the slot, a different output is given by the sensor providing positional confirmation for the control

program.

Flags are the appendages that change the signal of the slot sensors.

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Table 3: Input-Output Designations

Step Input Output Location Direction Time

1 Slot sensor (1) broken Transport motor (1) stops Filler To Filler 2 Reflective sensor (1) intact Filler places plate on cart Filler

3 Reflective sensor (1) broken Transport motor (1) activates Filler To MicroScan 4 Slot sensor (1) broken by flag 2 Transport motor (1) stops Filler

5 Reflective sensor (1) beam intact Filler places plate on cart Filler 6 Reflective sensor (1) broken Transport motor (1) activates

To MicroScan 10

7 Slot sensor (2) broken by flag 1 Transport motor (1) stops MicroScan 8 Slot sensor (2) broken by flag 1;

Reflective sensor (2) intact Activate actuator MicroScan

1

9 Reflective sensor (3) intact Pusher motor (2) activates MicroScan To Internal 2

10

Reflective sensor (4) broken by grips Pusher motor (2) stops; Remove current from actuator MicroScan

2

11 Micro switch tripped by plate Door motor (3) activates MicroScan

1

12

Reflective sensor (5) broken by door Door motor (3) stops; Pusher motor (2) activates

MicroScan, Internal To Internal 4

13 Reflective sensor (2) broken

Pusher motor (2) stops; Activate actuator Internal

1

14 Reflective sensor (3) intact Pusher motor (2) activates (reverse) Internal To MicroScan 6

15

Slot sensor (3) broken by pusher flag Remove current from actuator; Door motor (3) activates reverse MicroScan

1

16 Slot sensor (4) broken by door flag Door motor (3) stops MicroScan

2

17 Slot sensor (4) broken by door flag Transport motor (1) activates MicroScan To MicroScan 18 Slot sensor (2) broken by flag 2 Transport motor (1) stops MicroScan

19

Repeat 9-16

MicroScan, Internal

20

20 Slot sensor (4) broken by door flag Transport motor (1) activates reverse MicroScan To Filler 10

Repeat from 1

60

18

Figure 5: Process Flow Chart

19

Table 4: Transportation System Evaluation

Transportation system

Target Max Rating Rating Actual Rating Actual Rating Actual Rating Actual Rating Actual Rating Actual

Automation

# inputs to move 2 plates 1 5 4 1 4 1 4 1 2 2 4 1 4 1

Serviceability

Tools needed to access 2 5 4 1 3 2 4 1 2 >2 3 2 2 3

Maintenance Cost

<20% of

manufacturin

g price

5 5 5% 4 20% 4 20% 2 >20%of price 4 20 % < 4 20 % <

Complexity

standard:custom ratio 2:01 5 4 2:01 1 2:02 2:01 1 2:24 5 3:01 2 2:04

built-in control system? Y 5 4 Y 2 N 4 Y 4 Y 2 N 4 Y

# hardware to software

connections< 2 5 4 1 3 2 4 1 4 1 4 1 4 1

# variables (pos, motion) < 3 5 4 1 (steps) 4 1 4 1 (steps) 4 1 4 1 2 2

Reliability

Life of parts/subsystems >2.5years 5 5 >2.5 3 2 4 >2.5 4 >2.5 years 4 > 2.5 year 4 >2.5 year

Max dynamic force capability >50lbf 5 4 100 2 30 4 100 3 n/a 5 > 100 lbf 2 34 lbf

Number of Pieces 5 4 3 3 4 5 2 1 24 4 3 4 3

Specifications 5

Cycle time <30secs 10 10 1s 7 15s 8 5s 8 30 sec << 6 30 sec < 8 30 sec <<

Weight <40lbs 5 5 11 5 10 4 38 5 12 lb 5 5lb 5 15 lbs

Footprint (area) 304in^2 5 5 130 4 192 3 288 3 304 3 256.8 3 304

Clearance: cover to transport .5in 5 5 0.03125 4 0.25 3 0.5 4 0.25 3 0.5 4 0.25

Cost < $2500 5 4 $750-$850 4 $450-600 3 $1-2000 1 $4-5,000 3 $1-2000 3 $1500-2000

Total Score 85 71 53 58 48 59 55

Linear MotorHidden Belt Rack and pinion Conveyor belt Magnet Power Screw

20

Table 3: Pusher Evaluation

Yes/No

Metrics Target Value Active Four-Bar Passive

Automated Yes Yes Yes Yes

Access to

mechatronics Yes Yes Yes Yes

Interference

with carousel No No No No

Cover

maintained

on titer plate

Yes Yes Yes Yes

English Units Yes Yes Yes Yes

Weighted

Metrics

Target

Value Priority

Theoretical

Value Rating

Theoretical

Value Rating

Theoretical

Value Rating

Plate

displacement

accuracy

< 0.3" 30

Stepper

Resolution:

1.8°/step

30

Step

Resolution

+ Gear

Ratio:

<1.8°/step

30

Stepper

Resolution:

1.8°/step

30

Size of

component

entering

MicroScan

< 3" x

7" 25 1.5" x 4.5" 20.7 1.5"x7" 18.75 2" x 5.5" 17.9

Stroke length

capability

2" to

24" 20 0" to 10" 15.5 0" to 10" 15.5 0" to 10" 15.5

Total system

depth 24" 15 20" 12.5 12" 7.5 20" 12.5

Ratio of

standard to

custom parts

2 to 1 10 5 to 3 8.3 4 to 1 10 4 to 1 10

Total

number of

parts

8 12 4

Total 87 81.75 85.9

21

Table 5: Initial corresponding Wants and Metrics

Wants Importance Metrics

Transportation of the titer plates 25 Maximum travel time: 30 sec

Cross-contamination between wells: y/n

Micro plate lid through whole cycle: y/n

Automated loading into MicroScan 25 Number of operator inputs: <10

Easy access to mechatronics 15 y/n

Performance reliability

13

Operating temp range: 18-35 °C

Operating humidity range: 20-80% (non-

condensing)

Door cycle in under 12 seconds

Accompanying high quality animation 11 y/n

Adhere to RoHS environment standards 8 Sealed to IP61: dust and water resistant

Interfacing with filler machine 8 y/n

Small transporter/loader size

5

Area of existing machines, max.: 2 ft

Total weight under 50 lbs.

Maximum size of door opening: 3” x 7.5”

English hardware implementation 4 y/n

Adjustable transporter/loader height 2 Include leveling feet: y/n

Low cost 1 Maximum cost: $10,000

Total 117

Yes/No Metrics Target Value

Automated Yes

Access to mechatronics Yes

Interference with carousel No

Light-tight seal Yes

Thermally insulated door Yes

Sealed to IP61: dust and water

resistantYes

English Units Yes

Weighted Metrics Target Value Priority Theoretical Value Rating Theoretical Value Rating

Door opening area < 3" x 7.5" 30 Variable, 2" x 7.5" 20 3" x 7.5" 15

Door opening/closing time < 2 sec. 30 Variable, 1 sec. 22.5 Variable, 1 sec 22.5

Approx. door system weight < 10 lbs. 20 1 lb. 19 0.4 lbs. 19.6

Distance microplate starts

away from system< 2 ft. 10 4 in. min. 9 4 in. min 9

Ratio of standard/custom parts

(complexity & cost)2 to 1 10 2 to 1 10 2 to 5 2

Total number of parts 6 7

Total 100 80.5 59.1

Yes

Yes

Yes

Yes

Yes

Yes

Four-Bar

Yes

Yes

No

Yes

Direct Drive

Yes

Yes

No

Yes

Table 4: Door System Evaluation

22

Table 6 - Project Progress

31-Aug 15-Sep 6-Oct 26-Oct

Phase 1 : Define Project

requirements

1.1 Define Wants , Needs and constraints

1.2 Benchmarking

1.2.1 Doors

Dan McCarthy & Dan Russakow

1.2.2 Transportation system

Leah Putman & Maxime Dempah

1.2.3 Existing devices

Team

1.2.4 Gears, actuators

Leah Putman & Paul Masullo

1.3 Define metrics

1.4 Metrics results

Phase 2 : Concept Proposal

2.1 Concepts

developments

Break into subsystems

Doors

Dan McCarthy & Dan Russakow

Pushers

Paul Masullo, Leah Putman, Dan

Russakow

Transportation system

Maxime Dempah & Leah Putman

2.2 Selection of a conceptual design

2.3 Development of project schedule

2.4 Project budget

23

6-Oct 26-Oct 23-Nov 7-Dec 10-Dec 17-Dec

Phase 3 : Concept Design

3.1 Design Details

3.2 Design Specifications

3.2.1 Engineering Drawings

3 people: Door/Tolerancing- Dan M,

Pusher- Dan R, Frame- Max,

Miscellaneous- Paul

3.2.2 Purchased parts

Leah, Max

3.2.3 Installation Drawings

Dan M,

3.2.4 System drawings

Door- Dan M, Pusher- Dan R,

Transport/Frame- Max, Explanations-

Team

3.3 Analysis

5 people: Pusher Arm- Paul, Motors-

Leah, Double check- Dan R

3.4 Update project plan

Leah

24

Table 7: Prototype Parts, Materials, and Cost

Part Description Manufacturer Part Number Supplier Quantity Price/Unit Total

Pusher

Zinc- Stl Button Head Torx Machine Screw 10-24 T,

1/2" L McMaster 90910A242 McMaster 1 Pack (of 100) $10.73 $10.73

18-8 Stainless Steel Machine Screw Hex Nut 10-24 Thr,

3/8" W, 1/8" H McMaster 91841A011 McMaster 1 Pack (of 100) $4.11 $4.11

24 DP, 24 Teeth, AGMA 10, Acetal gear with Pin type

hub SDP-SI

S1086Z-024DS024

SDP-SI 1 $23.13 $23.13

24 DP, 20° Pressure Angle, #416 Stainless Steel Rack

SDP-SI S1809Y-RA-1P SDP-SI 1 $60.58 $60.58

SAE 841 Bronze Flanged-Sleeve Bearing for 1/2"

Shaft Diam, 5/8" OD, 1/2" L McMaster 6362K101 McMaster 2 $1.11 $2.22

Rulon LR Sleeve Bearing for 1/8" Shaft Dia, 1/4" OD,

1/4" L McMaster 6362K101 McMaster 2 $1.25 $2.50

STA 3/4'' x 1-1/2'' Push Actuator

Ledex 195205-231 (20M1817)

Newark ( Part #)

1 (Minimum order of 50)

$26.20 $26.20

D2 Tool Steel Tight-Tolerance Rod 1/8" Diam, 1'

L McMaster 88565K35 McMaster 1 $7.08 $7.08

Multipurpose Aluminum (Alloy 6061) 2-1/2" Thick x

4" W x 1' L McMaster 8975K326 McMaster 1 $77.11 $77.11

Multipurpose Aluminum (Alloy 6061) 3/8" Thick, 6"

W, 1' L McMaster 8975K441 McMaster 1 $17.72 $17.72

High-Strength Aluminum (Alloy 2024) 5/8" Thick, 3/4"

W, 1' L McMaster 89215K489 McMaster 1

$ 18.50

$18.50

Hybrid Stepper Motor Minebea 23KM-K035-

49W (1000010100)

Siemens (Part #)

1 (In-House) $0

Door

Hybrid Stepper Motor Minebea 17PM-K406-

02W (1000010022)

Siemens (Part #)

1 (In-House) $0

Miniature Precision 12L14 Drive Steel Shaft 1/4" OD,

4" L McMaster 1327K114 McMaster 1 $3.34 $3.34

25

Miniature Al Base-Mnt SS Ball Bearing--ABEC-3 for

1/4" Diam McMaster 8600N3 McMaster 2 $14.48 $28.96

Multipurpose Aluminum (Alloy 6061) .190" Thick, 12"

X 12" McMaster 89015K31 McMaster 1 $35.19 $35.19

Corrosion-Resistant Aluminum (Alloy 5052) #4 Satin Finish, .100" T, 12" X

12"

McMaster 8199K15 McMaster 1 $17.18 $17.18

Multipurpose Aluminum (Alloy 6061) 1-1/4"T x 1-

1/2"W x 1 L McMaster 8975K671 McMaster 1 $17.06 $17.06

Shaft coupler 6mm to 1/4" Misumi USA U-CPRC20-L6-

R0.25 Misumi USA 1 $12.90 $12.90

Zn-Plated Stl Flat Head Socket Cap Screw 8-32 Thr,

1/2" L McMaster 91263A524 McMaster 1 box (25) $6.25 $6.25

Zn-Plated Alloy Steel Socket Head Cap Screw 4-40 Thr,

1" L McMaster 90128A115 McMaster 1 box(10) $5.29 $5.29

Titanium Hex Nut 4-40 Thread Size, 1/4" Width,

3/32" Ht McMaster 90545A005 McMaster 2 $4.90 $9.80

Pan Head Phillips Machine Screw Zn-Plated Stl, M3,

10mm L, .5mm P McMaster 92005A120 McMaster 1 box (100) $2.30 $2.30

Titanium Hex Nut 8-32 Thread, 11/32" W, 1/8" H

McMaster 90545A009 McMaster 2 $3.83 $7.66

Seal Strip McMaster 8694K16 McMaster 1 $5.13 $5.13

Insulation McMaster 86375K152 McMaster 1 $8.95 $8.95

Frame and Transport

Manual Slide Track 24inches 80/20 Inc 1001 Siemens 1 In-House 0

Floor Mount Base Plate 80/20 Inc 2380 Siemens 8 In-House 0

Deluxe Leveling feet 80/20 inc 2192 80/20 inc 9 In-House 0

Fractional T-Slots 17 inches 80/20 Inc 1010 80/20 inc 3 In-House 0

Fractional T-Slots 10 inches 80/20 Inc 1010 80/20 inc 4 In-House 0

Fractional T-Slots 22.62 inches

80/20 Inc 1010 80/20 inc 4 In-House 0

Fractional T-Slots 3.66 inches

80/20 Inc 1010 80/20 inc 2 In-House 0

Fractional T-Slots 2.75 inches

80/20 Inc 1010 80/20 inc 2 In-House 0

Fractional T-Slots 3.15 80/20 Inc 1010 80/20 inc 4 In-House 0

26

inches

2 Hole 1/8” Inside Corner Bracket

80/20 Inc 4108 80/20 Inc 18 In-House 0

Bolt Assembly Package 80/20 Inc 3386 80/20 Inc 18 In-House 0

Rounded Tri Corner Connector

80/20 Inc 4041 80/20 Inc 4 In-House 0

Electronics

Stepper Controllers Minebea 1000034460 Siemens 2 $288.00 $576.00

Computer with LabView Siemens 1 In-House $0.00

SENSOR REFLECTIVE SIDE ASSY

1000018996 Siemens 6 $8.99 $53.94

SENSOR PROXIMITY SHIELDED ASSY

1000027598 Siemens 3 $7.99 $23.97

PLC Unit Siemens 1 In-House $0.00

Machine Shop Rate

(per hr) 21.5 $75 $1,613

Electric Shop Rate (per Hr)

2 $75 $150

Grand Total $4,626.30