Medication Dispensing Device

Kevin Villani, Eva Marie Suarez, Jacquelyn MasseTeam 6

RERC ACCESSIBLE MEDICAL DEVICE COMPETITION 2005-2006Contact: John Enderle University of Connecticut 260 Glenbrook Road

Storrs, CT 06269-2247 Phone: (860) 486-5521,

TABLE OF CONTENTS

Abstract………………………………………………………………………...……2Introduction……………………………………………………………………...….3

Background……………………………………………………………….........3Clients……………………………………………………………………….…...3Market Research…………………………………………………………….....4Patents Published…………………………………………………………...…6Analysis…………………………………………………………………….……7

Discussion……………………………………………………………………….….9Design One……………………………………………………………….……..9Design Two………………………………………………………………....…10Design Three……………………………………………………………….....13Optimal Design Selection………………………………………………..…15Optimal Design Objective……………………………………………..……16Optimal Design Subunits…………………………………………………...17

Basic Components and Locations……………………………..…17Vacuum Fan Requirements……………………………………..….18Robotic Arm…………………………………………………………...19 Servo Operating Theory and Circuits……………………….19 Vacuum retrieval assembly……………………………………20Pill Capture and Cutter………………………………………………21Storage assembly……………………………………………...……..25PDA and LabVIEW……………………………………………….…...26Barcode Scanner……………………………………………………..28Dispensing Assembly…………………………………………….....30Pathway of the Pill……………………………………………….…...31

Budget………………………………………………………………………….…..32Timeline……………………………………………………………………….……33Conclusion…………………………………………………………………….…..36References…………………………………………………………………….…..37Acknowledgements……………………………………………………………...38Appendix……………………………………………………………………….….39

Specifications…………………………………………………………….39 Purchase Order Requisitions……………………………………..….41

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ABSTRACT

There are several devices available on the market that provide medication dispensing at a predetermined time and are also light and portable. The additional features on each of the products vary but none of them are as automated as some clients with disabilities require. The medication dispensing device will contain the same basic features several of the products on the market advertise, such as an alarm indicating when a dosage must be taken and a record of pills that need to be dispensed. In addition to these standard features, the medication dispensing device will also be capable of cutting pills and tablets of various shapes and sizes into halves and quarters. Another feature of this device is its easy loading, requiring no individual container per dose or cassette loading.

The medication dispenser’s innovative design consists of a robotic arm and cutting assembly which utilizes the symmetry of the pill to guide the position of the blade. The vacuum on the robotic arm provides a means of transporting the pill from the storage container, to the cutting assembly, and finally the dispensing assembly. This device also allows the user via the PDA to obtain information about the medication being dispensed, record of pills dispensed, and activate the dispensing process once the alarm has sounded. This fully automated system will satisfy the needs of clients with limited mobility, eye sight, and memory.

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INTRODUCTION

Background

The pharmaceutical industry is a major component of U.S. economy. Scientific, social, aging demographic, financial, and convenience factors all contribute to its growth. Scientific breakthroughs are fueling the development of medications for conditions that were previously untreatable with drugs. People are increasing their use of “lifestyle” drugs, such as Viagra and more medication is being taken by senior citizens, especially as the baby boomer generation is aging. The expensive costs of prescription drugs are being made more affordable by many health plans. Furthermore, medications are increasingly being used to treat chronic disease as a convenient alternative to waiting until the condition requires surgery.

With individuals taking a growing number of different drugs, the market has developed several ways of making medications easier to handle. Products range from simple containers to store pill dosages per day, hand held pill cutting tools, and medication reminder alarms to more expensive, complex devices. Many of these devices can be problematic for people with poor eyesight, limited fine motor skills or mobility, Parkinson’s Disease, or other physical ailments. The lack of existing products on the market to suit such clientele gives rise to the need for an automated medical device that will administer medication to the patient in an accurate, dependable manner.

The device will be cost-efficient and reliable. It must remain accessible and easy to use for individuals who lack fine motor control, are vision impaired, or are limited by unsupported vertical access. The size and portability should be suitable for residential or clinical settings. Automation will be the device’s most distinguishing feature. It will mechanically regulate medication of 1, ½, or ¼ pills of various sizes and shapes and will manage many different medications at once. Ideally, the device will have alarms to signify the time medication needs to be taken or refilled. Information regarding dosage amounts, times, and expiration dates will be internally stored and a tracking system will record a history of dosages dispensed.

Clients

Bruce was born in 1960. He is an aerospace engineer and vehicle enthusiast who lives with his wife and one cat. In 1999, he was involved in a serious motorcycle accident which resulted in the paralysis of his legs and now he uses a manual wheelchair. He experienced renal failure in 2003 and takes a large number of medications daily.

Mary was diagnosed with Multiple Sclerosis in 1994. Over the past 10 years her condition has declined steadily. Now age 50, she uses a walker and is able to stand without support for 1 minute. She also has poor eyesight.

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Sophia was born in 1970 and emigrated to the U.S. from Poland in 1987. In relatively good health, Sophia had several small strokes in 2003, and now takes heparin as a precautionary measure. Sophia has limited right arm function and walks using a cane, but she continues her job as a social worker and is very active in the community.

Arnold was born in 1952 and since his heart attack in 1999 has worked in the mailroom of a large manufacturing company. He has diabetes and Parkinson’s disease, and experiences slight to moderate tremors. He lives alone.

Rose was born in 1941. She is blind and was recently diagnosed with lung cancer. With the recent death of her husband, Rose is about to move in with her daughter and son-in-law and her granddaughter, Wanda, but wants to maintain her independence as well as help out around the house as much as she can.

Market Research

There are currently several products on the market that claim to be medicine dispensers. The three most popular items are the MedTime Device, the MD2, and CompuMed. Each device has different characteristics which may be beneficial to some clients but an annoyance to others. These characteristic are described below:

MedTime: The Medtime product is essentially a rotating disk that contains several compartments in which the pills are separated into to create the appropriate dosage. The MedTime device also contains a timer and an alarm which can be programmed to sound when the medication must be taken. Once this alarm goes off, the disk rotates to reveal the next dosage to be taken. The client then turns the product over so the pills fall into his/her hand. If a dosage is missed then the disk will continue to rotate so that the next dosage becomes available. The advantage of this device is that it is portable, so it can be taken with the client at all times. This product is also one of the least expensive medication dispensing devices at $232.95. The disadvantages of this product are its time consuming loading requirement, the lack of a cutting device, and minimal security. To load the device all the dosages must be pre-separated which will require the effort of a caretaker in most cases. The dispensing mechanism of the device is also inadequate for many elderly, since it requires one to tip the device over to expel the dosage. Not only is the method of dispensing not safe if there are children present since it is accessible to anyone, but it also provides the opportunity for the medication to fall on the ground easily. Those in a wheelchair would not be able to pick up the medication if it fell on the ground as well as those with poor vision.

MD2: The MD2 is a more sophisticated medication dispensing device than the MedTime. This product contains the same feature of a timed dispensing mechanism with an alarm to alert the client. The dosage is expelled in a small plastic container once the release button is pushed by the user which also turns off the alarm. When a dosage is released any medication instructions that was

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programmed into the device is then given orally, such as ‘take with food’. If a dosage is missed the device can call up to four individuals to alert them that a dose was not taken. The advantages of this device is that it alerts another individual of a missed dose rather than moving onto the next one, so the probability of a dosage not being taken is relatively small. Clients that forget to take their medication are also likely to forget the instructions or each medication, an error in consumption of the pills is prevented with this device via the oral instructions. The disadvantage of this product is mainly its cost. The dispenser costs $919.95 plus an additional $38.95 per month for the calling feature. The product also does not have a cutter and has minimal security since the dispensing of the medication is controlled by the push of a button, which can be done by any individual in the household including small children. Dispensing the dosage in a small container also requires the assistance of a caretaker to prepare. Opening this container once dispensed may also prove difficult for some individuals with limited mobility and poor vision.

CompuMed: The CompuMed shares some similarities with both the MedTime and the MD2. This device alerts the user that a dosage needs to be taken via an alarm. The dosage is deposited into a small drawer located on the front of the device. If a dosage is missed the drawer is withdrawn and the dosage is sent to another compartment. The machine keeps track of how many doses were missed but does not alert any caretaker as the MD2 does. It will also provide the medication instructions on the LCD screen when a dosage is dispensed as the MD2. The CompuMed has a higher level of security than the other two devices. Although the dosage is deposited into a drawer where others can access it, the rest of the medication stored in the product is locked inside with a key. This key is also needed to change the programming of the device and thus prevents any tampering that may otherwise occur. The main advantages of this device are its enhanced security, and lower cost when compared to the MD2. The CompuMed costs approximately $1045.00, but does not have any additional monthly fees. The disadvantage of this product is that the medication is loaded into cartridges which is a time consuming process and limits the amount of medication that can dispensed. The cartridges need to be changed weekly and are only capable of dispensing up to four dosages per day. This device also lacks a cutting mechanism and dispenses the medication into a drawer which may be difficult to extract from the small drawer for some individuals.

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A summary of these devices is seen in the table below:

Product Name

Image PRO CON

MedTime

- Timer with alarm- Portable- $232.95

- Difficult loading- No cutting device- No security feature

MD2 - Timer with alarm- Gives medication instructions- Calls caretaker if medication not dispensed or refill is needed

- Dispenses in small container- No cutting device- No security feature- $919.95 plus $38.95 per month

CompuMed - Timer with alarm- Gives medication instructions- Minimal security- Tracks number of missed doses

- Pills deposited into drawer- Only dispenses up to 4 times per day- Medicine cassette needs to be changed weekly- No cutting device- $1045.00

Patents Published

There are also several patents published for various types of medication dispensing devices. A brief summary of the products proposed by each patent is included below:

Medication Dispenser for Dispensing Flat Dosage Forms (6,527,138): This device is designed specifically for flat mediations that come on a roll similar to that of a stamp roll. The device then advances the roll when the next medication needs to be taken. The dispensing mechanism can be either manual activated, mechanical or automated. The machine also has the capability to record the number of doses dispensed.

Tamper Resistant Programmable Medicine Dispenser (6,163,736): This device prevents unauthorized movement of the indexing assembler to prevent untimely

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access to medications. It is a small and portable product, but requires the medications to be separated into the appropriate dosages beforehand.

Medicine Dispenser (5,947,329): This product also provides a security feature against unauthorized access to the medication by storing the medication in sealed containers that require deliberate steps to get the medication dispensed. This device is completely mechanical and includes a counter to track the dosages dispensed.

Timed Medicine Dispenser (4,207,992): As the title suggests, this a timed dispenser which alerts the patient when the medication needs to be taken. The pills need to be pre-separated into the correct dosages as with several of the other devices.

Medicine Dispensing Device (5,454,793): This device is made specifically for liquid medications. It dispenses metered quantities from an ampoule and can easily return to its original state.

Gravity Feeding Pill Medicine Dispenser (4,638,923): This is the only device that dispenses the medication from the container provided by the pharmacy. It uses gravity to release the pills from the container. It is economical and easy to use, but does not contain a system to verify that the pills were extracted from the container correctly.

Analysis

Analyzing the products that are available on the market and those described in the published patents, there are several undesirable characteristics that have been identified that will be address by our medication dispensing device. The first of these characteristics is the need to separate the pills into the appropriate dosage before loading the device. This is a time consuming task, which can be eliminated by developing a system in which the pills are simply poured into the apparatus. Several of the devices described also make it difficult to extract the medications once dispensed from the apparatus. This product needs to designed for those who have limited mobility and poor eyesight, not just those with a poor memory. Most importantly, none of the devices contain a cutting tool; therefore all cutting must be done before the machine is loaded. This is again a time consuming step when loading the device and is also one that is impossible to complete for several clients without the aid of a caretaker.

In order to meet these requirements a high level of mechanical, electrical, and biomedical engineering will need to be implemented. The mechanical components for the robotic arm and cutting assembly must be precise and reliable, while the electrical circuitry synchronizes the various components of the device to function in an assembly line manner, as well as provide power to the motors. Biomedical engineering skills are needed to ensure the device is easy to use for

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the clients with a variety of disabilities, providing them the independence they desire.

The following sections provide detail about the final design and each of its subunits. Preliminary designs are also provided to demonstrate other considerations and reasons for choosing each of the components used to construct the final design. The budget and expected completion date for each task involved in the development of the device are presented, culminating in a conclusion about the device.

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DISCUSSION

Design One

The first design featured a track system where the vacuum assembly and the cutter could move over to the necessary storage container. This design also featured a weight verification system, to ensure accurate dosages are dispensed. All these components are located within the case to allow for ease of access and ease of replacement

The vacuum retrieval assembly is tasked with the retrieval of pills from the storage module for delivery to the rejection assembly at dispensing set points. The assembly is made of four components; pill retrieval vacuum tubing, supply tubing,

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Figure 1: Basic Component locations within the case

vertical displacement control and the proportioning valves. A vacuum is drawn on unit through the primary proportioning valve causing the assembly to lower into the desired storage module, with spring assistance, where at a specified height the secondary proportioning valve is actuated. A vacuum is drawn on the retrieval tubes setting up a pressure differential across the medication. This pressure differential holds the medication in place for transport to the rejection assembly. This rejection assembly consists of a platform on which the pill will rest on top of a load cell. The voltage output from the load cell will be translated into the corresponding weight and compared to a standard to determine of the pill is acceptable or should be rejected. If I pill is to be dispensed the platform on which the pill rests will tilt in one direction, or tilt in the opposite direction if the pill is rejected. This tilting mechanism is controlled by a stepper motor which is connected to the platform via a belt. The dispensing assembly is simply a “trap door” with which the medication rests until requested by the user. The user coded input sets a register within the microprocessor to 1, or on, and signals the door to open, dropping the medication into the users hand or container.

Pills that are rejected from the weight verification system are most likely those that were not cut correctly. The cutter assembly cuts the pills into halves or quarters and consists of a loader device, cutting blades, template and rotating base. The template on which the pill is deposited from the loader is rotated clockwise or counterclockwise to engage either the ½ or ¼ cutter blade. The cutting blade is then engaged and projected down to the medication thereby segmenting the medication into the require number of segments. From here the medication is delivered and extracted into the storage module. The cutter assembly will continue this cycle until all medication is segmented and in storage.

A Microchip’s PIC16F877-20/P microcontroller is used to coordinate the inputs of the user with instructional outputs to an LCD display. It will also perform the logic functions needed to signal the device components to run properly at the user-designated times. A real time clock or RC external oscillator to keep track of time is used to control the function of the alarm to alert the user a dosage needs to be taken.

The user interface allows the user to control device functionality by establishing the medication contained in the unit and the dosage requirements of the medication. The user is allowed to interface with the device through a numeric keypad and an LCD screen. This set-up minimizes the information the user must input to the device by simply prompting the user to input numerical values.

Design Two

The second design drastically changes the manner in which the pills are moved from location to another in the first design by utilizing a robotic arm and contains a different cutting mechanism. The components are again all contained within a casing for safety and maintenance ease.

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The robotic arm was chosen not only for the “bells and whistle” quality it possesses but also because it has a wide margin of versatility, one to one control over medication through process, allows for verification of medication at point of acceptance and retrieval. This particular robotic arm is made of plexiglass, once again for aesthetics and strength. The arm serves to accept medication fro the user, transport for storage, retrieval from storage and transport to pill capture and cutter and finally for transport to dispensing tray. The arm is modeled around a lynxmotion 6 axis arm. The major change being the addition of vacuum assembly and linear gripper to the arm. This arm contains five servo motors for movement in all directions. For assembly of this parallel plate robotic arm changes to the inter-dimensions between servo motors allows for a smaller over all design. The gripper assembly contained two piezo electric sensors to determine the pressure exerted on the pill vail. The action provided by the gripper is in one dimension to either open or close the unit. To operate the gripper assembly a stepper motor coupled to a screw gear rotates, the moveable arm is coupled to the screw and is moved linearly outward. The vacuum assembly maintains the same concept behind its function but is now mounted on the robotic arm and is rotated into position to pickup by a servo motor attached to the assembly. Once the robotic arm withdraws the pill from the container it is deposited as before onto the platform of the weight verification system, whose design and function remain the same as in design 1.

Design limitations of design 1 are directly answered with the secondary design of the pill capture and cutting device. This design removes the need for the user to load pill manually while still retaining as high accuracy is segmenting the medication dosage. As seen in research pills and tablets do not need to be cut along a score line to remain consistently segmented correctly. If fact personal research was conducted to cut tablets lengthwise with high accuracy. With this in

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Figure 2: Overall Layout

mind the secondary design approach to pill capture and cutting is centered about geometry. Assuming all pills or tablets that shall be cut have a point of symmetry about them the capture swing arm shaped as an arc is capable of placing the point of contact between the pill and the swing arm about this center of symmetry. In the same motion align the cutter along this center of symmetry. This orientation allows a pill to be segmented in half, by repeating the process ¼ segments are achieved. With each smaller pill the arc is rotated by torsion spring tension against a slight axial spin tension thereby positioning the pill to the center point. Concurrently the underside to the arc acted against the cutter “feeler” and spring tension (of cutter assembly) to reposition the cutter assembly. With this set up any symmetrical medication can be centered across the cutter blade providing accurate non-approximated center points. The assembly consists of a stepper motor, three ball bearing linear tracks, worm gear and pinion, torsion spring, two axial springs (one for the swing arm and one for the cutter assembly), base, cutter arm, stage, and sliding secondary stage.

All these functions are again controlled by a microcontroller, and utilize the same user interface as in design 1.

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Figure 3: Cutter

Design Three

The third design featured alterations to the robotic arm, a different layout of all the components, a new storage assembly, introduction to a barcoding system and PDA device, and the removal of the weight verification system.

The robotic arm has been design to be constructed of high density polyethylene due to its strength and chemical resistance. However prototyping the

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Figure 4: Overhead View

arm will be conducted with the use of a LEGO® robotic arm kit to allow for modifications and operating sequences. This arm has two axis of motion. The first is a horizontal swing arm with a range of 180 degrees limited to 90 degrees for this

application. The orientation of the swing arm allows for the placement of the vacuum assembly above any assembly located along the swing arm arc. Control of the swing arm is via a servo motor and the main PIC controller. The second axis of movement for the robotic arm involves the translation of the vacuum tube in the vertical direction. This allows the vacuum tube to drip into storage containers and to gently place medication on subunits. Control over this action is given to the stepper motor controller slaved to the PIC controller. The stepper motor is geared to a worm gear which in turn is coupled to the vacuum pick up unit. By rotating the stepper motor the worm gear is rotated, this rotation is converted to linear movement through the threads in the coupling. Rotation of the unit is prevented by two guide posts toward the front of the unit.

The storage assembly from which the pills are taken by the robotic arm consists of a of a storage reel segmented into twelve containers, a storage reel cover, fill cover and stepper motor. The storage reel is designed based on a fishing tackle holder. The compartments within the storage reel are designed such that the outer edge of each compartment is deeper then the inner portion. Inner and outer depths are connected by a continual ramp. This allows the medication stored within the compartment to fall by gravity to the lowest position as medication is withdrawn. Pills taken from the storage assembly can then be either dispensed or taken to the cutter assembly which remains the same as design 2.

Using a PDA has many advantages over using just a micorcontroller. The dominating advantage is the storage capabilities. By incorporating a PDA into the

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Figure 5: Robotic Arm

dispensing device, a large amount of information can be stored without the risk of losing it if power outages occur. A microcontroller will still control the motors of the cutter and robotic arm however; the PDA allows a separate program to control the calendar, clock, timers, data storage, and initiation of the device’s actions.

The program for the device will be written in LabVIEW. It will act as the computational link between the data stored in Excel (also stored on the PDA) and the microcontroller. It will track the number of pills dispensed and remaining and will control the timing of the alarms for expiration date and dispensing. The alarm and displays will output through the existing PDA screen and speaker.

Since the keys on the PDA are very small, a separate keyboard will be connected to the system for the users to access when turning off the alarm or entering pill information. A barcode scanner also needs to be integrated into the system. These two items will be inputs into a USB hub that then directs the information through a USB port to the PDA, where the information will be stored and dealt with by Labview and Excel.

The barcoding system will be used to reduce errors during the loading process and to identify the stored data for each medication. When a prescription needs to be loaded the client will scan the prescription using the barcode scanner located on the device. This reference number will be compared to those stored in the excel spreadsheet. The user may then indicate via the PDA any changes they are making to the amount of pills in the container or obtain information about the pills already in the device, such as expiration date, number released, etc.

When pills need to be taken, the same dispensing system as in the previous designs will be implemented.

Optimal Design Selection

This device has several constraints that helped to determine the optimal design. Perhaps the most significant constraint was regarding health and safety. Since the device will be responsible for providing medications, malfunctions or inaccuracy in the device may be life-threatening to the patient. The pills must cut and deliver the right number of pills at the right time. Stored pills must not be exposed or dispensed before the user is ready to take them because of the risk of contamination or children taking them. Based on the clientele, the device has to be user friendly for the seeing impaired and for clients with limited mobility. Ease of use should allow clients to maintain their independence. The device has to accommodate enough different medications for the clients’ needs and must be small enough to use in a home setting. Economic constraints include a $2000 budget and limited time to complete the project. Dust from cut pills and the danger of light and heat degrading the pills’ effectiveness are environmental considerations. Manufacturability was another consideration when deciding parts and assembly.

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Objective

The optimal design features the use of a vacuum mounted upon a robotic arm that can tilt upward and swing in a horizontal arc to control the flow of pills between the user, cutter, storage, and dispensing funnel. The horizontal arc movement of the arm is controlled by a servo motor and the vertical movement by a stepper motor. The use of arc movement reduces space, parts, and I/O needed for the device. Both motors are controlled by a PIC controller. The stepper motor is geared to a worm gear which is coupled to the vacuum unit. The vacuum is composed of the pill retrieval tubing, proportioning valve and supply tubing. Using the vacuum eliminated the risk of retrieving the wrong number of pills, a major concern in the design of this project.

The cutter assembly uses our innovative technique that relies on the robotic arm and the geometry of the pill and capture arm to remove the need for manual loading of pre-cut pills into a cartridge. The robotic arm places the pill on the cutting zone where an arc shaped arm sweeps across the surface to pin the pill against a straight edge. The point of contact between the pill and the arc is a point of symmetry on the pill and is directly associated to the position of the cutter which can then slice the pills, regardless of the score line’s position. Utilizing the robotic arm again, pills can be set aside to be cut again into fourths. Besides being more automated than the previous design, this design takes up less space, less parts, is quicker, and is just as accurate. After being cut, the pills are moved to a compartment within the 12 slotted storage reel that has a cover to reduce contamination and a stepper motor to control rotation.

Another unique feature about our design is the use of a Tungsten E2 Palm PDA and LabVIEW to store data and initiate commands. The PDA has many features that save time and reduce the amount of programming we have to do. The enormous storage capabilities allow us to load Excel and LabVIEW onto the PDA and use these programs to store data about medication and VIs that will run the device. The PDA also has a built in clock, calendar, and alarm to use for notifications. The PDA will communicate with the motors via a data acquisition unit. With 12 I/O lines, the DAQ can communicate with the motors. The DAQ will be connected to a USB hub to communicate with the PDA, as will a keyboard and a barcode scanner. The keyboard will allow the user to manually input medication information if necessary and the barcode scanner can scan medications with previously stored data. Using the barcode scanner reduces the amount of setup the user has to go through when adding pills to the device and reduces errors that could otherwise occur if medication information had to be input manually every time. The scanner uses a laser, photo diode, and decoder to convert a barcode to a 12 digit reference number. The number is associated with a set of data that is stored in Excel on the PDA.

The outer casing will contain all of the components. Due to the arc shaped placement of the components, the device will be shaped like a quarter-circle, fitting nicely into countertop corners. The casing effectively protects the pills from exposure to light or other contaminants that could degrade the pills.

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All of the components of the medication dispensing device were chosen to suit the requirements and constraints associated with the project. Our optimal design has a competitive price, a high level of automation and accuracy, and suits the needs of our clients. With proper licensing rights from National Instruments, this project could be manufactured and marketed to the general population.

Subunits

Basic Components and Locations

Components are located within the case, located to allow for ease of access and ease of replacement. Above is a component breakdown of major assemblies within the device.

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Figure 6: Overhead View

Vacuum Fan Requirements

Based on the maximum pill weight and the minimum pill thickness a vacuum requirement is identified. This requirement provides the differential pressure across the medication to ensure the medication can be removed from the storage module and delivered to the rejection assembly. By using simple pressure and weight definitions a relationship for the required differential pressure is attained. By measuring several over-the counter and prescription medications a minimum thickness was found to be 4 mm, while the maximum mass was approximately 1000mg. Substituting these values into the equation below a net pressure difference required was found to be 6.4kPa. In more traditional units of vacuum this corresponds to 1.94 in Hg. Keeping in mind that traditional vacuum systems draw a vacuum of 27 to 29 in Hg. Centrifugal fans systems are evaluated in meters of water, the range of operating head is 0.5 to 1.5 meters of water. The corresponding required differential pressure is 0.0622 meters of water, well within expected operating head.

To satisfy this requirement we have selected a fan impeller from a dirt devil 6000 series battery vacuum. The vacuum sells on-line for approximately $55 however, the impeller is also available for sell for $4.95.

Using a centrifugal fan impeller has several advantages over other vacuum generating options. First the price centrifugal fans are lower. Secondly, a centrifugal fan reaches shut off head. This shutoff head prevents drawing too high of a vacuum while still maintaining the fan in operation. This means that for our application there is a requirement that a pill be held by the vacuum tube and moved. By reaching shutoff head the pump will continue to spill however moving no air unless air slips into the system either from leakage by the pill or across the pump. Third this pump weighs less and is far easier to construct than other vacuum assemblies.

The vacuum fan assembly will be driven by 120 VAC power source Fan and system characteristic curves are used to determine the flow rates and pressures within closed systems. By measuring the differential pressure across the fan at various speeds and volumetric flow rates, a graphical representation of the fan operating characteristics can be achieved. Coupling this operating characteristic curve and a system operating curve; specific system flow rates and operating pressures can be determined by the points of intersection between the various curves, commonly referred to as “fan laws”.

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Figure 7

P = F/AF =mgA= πr2

Therefore,P= mg/ πr2

(Equations)

Figure 8. Servo motor(Parallax)

Robotic Arm

The major transport method employed by this device is the use of a robotic arm. The robotic arm was chosen not only for the “bells and whistle” quality it possesses but also because it has a wide margin of versatility, one to one control over medication through process, allows for verification of medication at point of retrieval. The Robotic arm is used to move medication from storage to the cutting assembly and from storage to dispensing. Several additional actions are required from the arm as part of cutting sequences and loading sequences. The Robotic arm will be constructed of high density polyethylene due to its strength and chemical resistance. This arm has two axis of motion. The first is a horizontal swing arm with a range of 180 degrees limited to 95.5 degrees for this application. The orientation of the swing arm allows for the placement of the vacuum assembly above any assembly located along the swing arm arc. Control of the swing arm is via a servo motor and the PDA running LabVIEW through a data acquisition box(DAQ). This servo motor requires a command wire besides a ground and positive 6V power supply. The command wire requires the use of one analog channel from the DAQ box. Operating the servo motor requires the following knowledge.

Servo Operating Theory and Circuits-A servo is a geared microprocessor controlled DC motor. Generally servos sweep over a 180 degree arc. However, removing the stops within the servo and changing the programming allows for operation at arcs greater than 180 degrees. The servo controls of the robotic arm require only 90 degrees of rotation. A probable candidate for the servo required is Parallax 6 volt servo pictured to the left. The operating circuit for this servo is in Appendix I. Basic servo theory is centered on changing the pulse width of the control signal. This change in pulse width corresponds to a position of the servo motor. A 1.0 ms pulse

rotates the shaft all the way counter-clockwise.  A 1.5 ms pulse puts the rotor at neutral (0 degrees), and a 2.0 ms pulse will position the shaft all the way clockwise.  The pulse is sent to the servo at a frequency of approximately 50 Hz.  The relationship between the pulse width and the rotor position can be seen in the picture above.

The second axis of movement for the robotic arm involves the rotation of the vacuum tube and retainer about its axis. This allows the vacuum tube to drip into storage containers and to

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Figure 9 (Lyxnmotion)

gently place medication on subunits. Control over this action is given to the servo motor controller slaved to the PDA through the DAQ box on a single analog channel. The arm and second axis (containing the vacuum assembly) can be seen

in

the component breakdown illustration below. Further the action of the robotic arm unit is pictured below:

Vacuum Retrieval Assembly-This assembly is tasked with the retrieval of pills from the storage module for delivery to the pill capture and cutting station at dispensing set points. The assembly is made of five components; pill retrieval vacuum tubing, supply tubing, servo motor and the proportioning valve. A vacuum is drawn on unit through the proportioning valve setting up a pressure differential across the medication. This pressure differential holds the medication in place for

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Figure 10: Robotic arm

transport to the pill capture and cutting station. Pressure is passed back through the proportioning valve allowing a discharge pressure to release the medication from the pick up tube. The type of device was chosen to reduce the possibility of drawing multiple medications in a single pass. This single event can then be related more accurately to pill retrieval numbers.

From the discussion of vacuum fan requirements the area of the pill pickup tube is approximately 1.26e-5 m2 or a circle with a 4mm diameter. The proportioning valve is located at the rear of the robotic arm and controls flow into an out of the pill pick up tubing. The vacuum pick up tube and retainer is rotated into position by a servo motor, approximately a 45˚ change in retainer position.

The proportion valve is a Burkett (6012) 3-way valve operating with the following technical requirements. When deenergized the valve is positioned to relieve pressure to atmosphere. When energized to valve positions to permit vacuum pressure to be felt in pick up tube. The required operating voltage is 24V DC±10% or 24V AC. Maximum operating temperature is 130F at a maximum viscosity of 21 cSt. The response times for this valve are opening 7-10 ms and closing 7-12 ms (DC).

Pill Capture and Cutter

Design limitations of design 1 are directly answered with the secondary design of the pill capture and cutting device. This design removes the need for the user to load the pill manually while still retaining as high accuracy as segmenting the medication dosage. As seen in research pills and tablets do not need to be cut along a score line to remain consistently segmented correctly. In fact personal research was conducted to cut tablets lengthwise with high accuracy. With this in mind the secondary design approach to pill capture and cutting is centered about geometry. Assuming all pills or tablets that shall be cut have a point of symmetry about them the capture swing arm shaped as an arc is capable of placing the point of contact between the pill and the swing arm about this center of symmetry. In the same motion align the cutter along this center of symmetry. This orientation allows a pill to be segmented in half, by repeating the process ¼ segments are achieved.

To examine the operation of this device a closer look into the geometry of the argument is needed. By looking at the complete circle and taking into account the changes in the x direction of the circle, a cosine wave form can be produced. The portion of this waveform of interest is from 0-90 degrees. Where 90 degrees is the minimum pill size relates to the maximum negative adjustment of the cutter assembly. Conversely, 0 degrees relates to the maximum pill size and zero cutter adjustment. By mechanically and continuously sampling the x position of the arc a direct connection is made to the adjustment of the cutter assembly.

In this device the arc and cutter assembly are not linked but rather in contact with one another. The set up of the cutter assembly places the blade of the cutter at the center point of the arc and the “feeler” side of the cutter in contact with the arc. A plumb line is drawn from the innermost portion of the contact of the arc and cutter assembly. This plumb line extends a length slightly larger then the magnitude of the cutter adjustment. With each smaller pill the arc is rotated by

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torsion spring tension against a slight axial spin tension thereby positioning the pill to the center point. Concurrently the underside to the arc acted against the cutter “feeler” and spring tension (of cutter assembly) to reposition the cutter assembly. Note from previous discussion the changes in the x-direction of the arc are translated one for one to the cutter assembly. With this set up any symmetrical medication can be centered across the cutter blade providing accurate non-approximated center points.

While the positioning capability of this sub unit are key, this sub-unit contains or supports the major differentiating function of the overall device as well as provides a far superior design to design one. The functions of this assembly are to accept, capture, cut and deliver medication. Capture and cutting have already been covered in a preliminary seems. To evaluate the function of this sub assembly a complete sequence of operation should by addressed to understand the interconnection of devices. The assembly consists of a stepper motor, three ball bearing linear tracks, worm gear and pinion, torsion spring, two axial springs (one for the swing arm and one for the cutter assembly), base, cutter arm, stage, and sliding secondary stage.

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Figure 12

The base unit carries the weight of all components. The three ball bearing linear tracks are mounted parallel across the base perpendicular to the cutter arm. The main stage is mounted to the top two ball bearing linear tracks and is coupled to the worm gear shaft via treaded couplings. This permits the stage to project out from the base is the direction of the linear tracks by action of the pinion gears

coupled to the stepper motor. Noting the accuracy of the linear movement of the stage is not associated with the accuracy of the cuts. Rather the gearing is designed for higher rates of projection and retraction. Most important to this actuator is the ability to satisfy cutting conditions. Those conditions are that the stage is fully retracted and the arc is in contact with the cutter “feeler”. The base is also used to attach the cutter arm as well as routing power lines.

The main stage contains the swing arm and secondary stage. The action of the secondary stage is to slide open perpendicular to the motion of the main stage providing a means for removal of segmented medication. The action is provided through the main worm gear energy by coupling that energy to a slotted groove located at a hyper-extended region of the main stage. The hyper-extended range is at a distance equal to the maximum opening range of the secondary stage past to point of acceptance of medication. The most crucial component in the design is the swing arm. Balancing the load of three springs allows for the alignment of the cutter. To begin in the closed position the swing arm is at approximately 80 degrees (maximum negative adjustment). This position reduces the opening axial spring deformation while loading the cutter spring. The main stage is projected outward to the medication acceptance point where the opening spring force builds

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Figure 13: Cutter Operation cycle

(assisted by the cutter spring) to open the swing arm against the torsion spring tension. At the medication acceptance located the swing arm is in the minimum adjustment position, providing the maximum area for deposition of the medication. After deposition of the medication the main stage is retracted. Now the torsion spring overcomes the opening spring and cutter spring tension due to the relaxed nature of the opening spring. This positions the medication and forces the cutter into position. At the fully retracted position the cutter is engaged after conditions met. The cutter is operated through the use of a servo motor in contact with the cutter arm. Rotating of the servo forces the cutter arm shut against torsion spring

tension in order to put force on the tablet. The blade is shaped as to pass by the retention arm and in between the swing arm. This cutter will not cut completely through the pill. Penetration of approximately 1/3 of the tablet thickness is required to cause a cut segmentation (determined experimentally with the use of a commercially available pill cutter.) Below is illustration of the cutter component breakdown and operation. At this time the main stage is again projected past the acceptance region to the dispensing region. To prevent damage to the opening spring a secondary spring with a spring constant lowered than the elastic region of the primary opening spring begins to give way. At this point the swing arm is balanced in the open position allowing the medication to be forced against the swing arm and off the secondary stage. The pills fall into an intermediate storage bin which rotates to a position outside the stage assembly. This rotations position another identical storage bin below the secondary stage. This operation is preformed to prevent confusion of segment sizes during subsequent segmentation (¼ segmentation) as well as facilitation for transport to the rejection assembly. The secondary stage movement is provided by a channel and pin assembly. The pin engages the channel just past the acceptance region and provides the anchor point for the stage to slide outward using the primary stepper motor energy.

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Figure 14: Cutter Side View

Storage Assembly

The storage assembly consists of a of a storage reel segmented into twelve containers, a storage reel cover, fill cover and stepper motor. The storage reel is designed based on a fishing tackle holder. The compartments within the storage reel are designed such that the outer edge of each compartment is deeper then the inner portion. Inner and outer depths are connected by a continual ramp. This allows the medication stored within the compartment to fall by gravity to the lowest position as medication is withdrawn. A reference slot, in blue, will provide the PDA with a reference position so that compartments can accurately be determined. Possibly the use of a limit switch will provide sufficient control over the outer edges of the primary compartment allowing the PDA to have an indication of storage reel position for reference. Rotation of the storage reel is controlled via a stepper motor mounted to the outer edge of the storage reel. During storage reel rotation the storage reel cover remains stationary. The reel cover contains two openings, one for withdrawal of medication by the arm and one for filling storage locations. To cover the fill location during operations a user operated fill cover is positioned over the fill location sliding out from below the fill funnel when needed.

Control of the stepper motor is accomplished through the use of a stepper motor controller slaved to the PDA through the DAQ. This requires the use of 3-4 four digital pins of the DAQ. Compartments are determined as a number of turns from the reference slot, this allows the PIC controller to retain positive control over the position of the compartment relative to opening. A potential draw back to this type of control is in the case of power loss. The stepper motor position will be unknown. To combat this situation the PDA will return the storage reel to the reference position and then reposition the reel to the proper opening. The storage assembly is pictured below showing the component exploded view on top and a typical rotation of the unit below.

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Figure 15: Secondary Stage motion

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Figure 16: Storage Assembly

PDA and LabVIEW

Using a PDA has many advantages. The dominating advantage is the storage capabilities. By incorporating a PDA into the dispensing device, a large amount of information can be stored without the risk of losing it if power outages occur. A data acquisition box will control the cutter and robotic arm however; the PDA allows a separate program to control the calendar, clock, timers, data storage, and initiation of the device’s actions.

The program for the device will be written in LabVIEW. It will act as the computational link between the data stored in Excel (also stored on the PDA) and the data acquisition device. It will track the number of pills dispensed and remaining and will control the timing of the alarms for expiration date and dispensing. The alarm and displays will output through the existing PDA screen and speaker.

Since the keys on the PDA are very small, a separate keyboard will be connected to the system for the users to access when turning off the alarm or entering pill information. A barcode scanner also needs to be integrated into the system. These two items will be inputs into a USB hub that then directs the information through a USB port to the PDA, where the information will be stored and dealt with by LabVIEW and Excel. We can use TRENDnet's TU-400E, a highly integrated 4-port USB hub. It consists of one upstream and four downstream ports. It is compact, light-weight, requires no external power, and only costs $6.78.

The PDA chosen for this design is the Tungsten E2, made by Palm. It has non-volatile memory which means that the data will be safe even if the PDA runs completely out of battery power. Only palmOne models and the import Sharp Zaurus line of Linux PDAs are the only PDAs on the market to use 100% non-volatile memory. This feature is especially important because of the complicated process of storing and programming the dosage times and the need to keep a history of the pills dispensed. The Palm includes a calendar that we may incorporate into our timing and alarm functions. It saves energy by entering a sleeping mode, but will wake up to beep or vibrate. The PDA is also affordable at $150.

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Figure 17: 4-port USB Hub

In order for the PDA to communicate with the motors, a data acquisition unit is required that will be connected to the PDA via a USB hub. Using 12 digital I/O lines, 8 analog input lines, 2 analog output lines and full speed USB interface the DAQ made by National Instruments (model number NI USB-6008) has plenty of capability for our needs. Nine of the digital input/output lines will be used to control the motors. The motors that control the cutter, temporary storage stage, robotic arm, and storage tray consist of two stepper motors and three servo motors. Three of these lines will control the function of the three servo motors; the other 6 lines will control the function of each of the stepper motors, 3 lines for each motor to control the output enable, direction, and speed. The digital output from the data acquisition device will be connected to each of the motors via a buffer circuit that will protect the data acquisition device as well alter the signal to meet the signal requirements of each of the motors. The data acquisition box will also accept inputs from the switches used to indicate when the motors have reached a home position. These signals will be accepted by the data acquisition device via the analog input ports. The LabVIEW program will translate these signals into a digital signal utilizing Boolean expressions. The DAQ, as well as the USB HUB and the PDA are all compatible with Windows 2000.

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Figure 18: Tungsten E2 Palm PDA

Figure 19: Data Acquisition Device

Below is a flow diagram of data through the device.

Barcode Scanner

A barcoding system will be implemented to reduce errors during the loading process and to identify the stored data for each medication. Almost all prescriptions that come from the pharmacy utilize a barcode to link the medication to the patient's history, this ensures that the correct medication and dosage is being given to the patient. The medication dispenser will also utilize this UPC number provided by the pharmacy to store similar information on the PDA. The UPC number is simply a reference number that will correspond to a row of data in a Microsoft Word Excel spreadsheet that is stored in the PDA. This row of information will contain the UPC reference number, the number of pills stored in the module, the required dosage, the container number in which the pills will be stored, the number

29Figure 21 - IDAutomation USB Barcode Scanner

Figure 20: Flow of Information

of times per day the medication should be dispensed, the time at which each dosage should be dispensed, the size the medication needs to be cut down to if necessary, and the expiration date. The information stored in the excel spreadsheet can then be used to track the medication within the LabVIEW program. This data will be pre-programmed in the device to reduce the amount of effort required by the user for initial set-up. When a prescription needs to be loaded the client will scan the prescription using the barcode scanner located on the device. The scanner uses a laser to scan the bars and measures the intensity of the light reflected via a photo diode which generates a waveform corresponding to the width of the bars and spaces. The decoder receives this wave and converts it to the 12 digit number that will be used as a reference number in our application. The keyboard wedge scanner chosen for this application is the IDAutomation Plug 'n Play USB Barcode Scanner. This particular scanner was chosen based on its easy installation process, USB connection which is compatible with the PDA, and built-in decoder which transmits the data as if it were typed from the keyboard. This scanner also does not require the use of any additional software, thus reducing the overall cost of the device and the amount of memory needed for the PDA. The scanner automatically inserts the 12 digit number wherever the cursor lies regardless of the program being used. When a client needs to reload the device, the barcode on the prescription is scanned. This code is then entered into the LabVIEW program and compared to each reference number stored in the excel spreadsheet. When a match between the scanned number and the reference numbers stored in the spreadsheet has been located, the LabVIEW program will withdraw the number of the storage module for that medication from the spreadsheet, and then activate the microcontroller to send a signal which will turn the storage container apparatus until the container with that assigned number is in the loading position. After more pills are added the LabVIEW program will prompt the user to enter in the number of pills added and the new expiration date using the keypad provided, and will store this new count and date into the excel spreadsheet. The program will then use the data of the spreadsheet indicating the size the pills needs to be to either move the pills to the cutting assembly or leave the pills in the storage assembly. The number of pills added that was entered by the client is then used to indicate the number of loops the cutting assembly must complete in order to cut all the medication. The spreadsheet will also provide the necessary information for dispensing of the medication. Where the time that the medication needs to be dispensed will prompt the dispensing portion of the LabVIEW program to run. The number of pills to be dispensed is also extracted from the excel spreadsheet, indicating the number of loops the program must perform, one loop for each pill dispensed. The use of the barcode system allows for the device to become more automated, thus reducing the possibility of human error. This reference number provides the necessary link between the LabVIEW program and the excel spreadsheet containing the data about each medication. If a barcoding system were not used, the client could easily forget which pill is located in which storage container, possibly loading a medication into the wrong container which will then

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cause that medication to be cut and dispensed incorrectly since the data from the medication previously stored in that container is being applied to the new medication. If the medications have different dispensing times and dosages, an error in the loading process can severely affect the health of the client and may even prove fatal. The use of the barcode minimizes the possibility of these errors

occurring due to its high accuracy. The accurate reading of the barcode can be attributed to its start and stop characters as well as the checksum feature. The start and stop characters indicate where the code begins and ends which allows to machine to detect whether the code is being scanned forwards or backwards. This feature allows the user to scan the code without worrying the direction the code is facing, thus reducing human error. The 12 digit number read from the barcode is also verified using the checksum number, which is the last digit of the code. This number is calculated by a series of computations using each of the individual digits of the 12 digit code. If the number calculated from the 12 digit number read by the scanner does not match the last digit on the barcode, the number is discarded and the scanner re-reads the barcode. This feature again reduces error, ensuring that the number read by the scanner is the same number on the barcode.

Dispensing Assembly

The medication will be deposited into a container that is easily accessible to the client. Since the client must activate the device to begin the dispensing process after the alarm has sounded, a secondary guard, such as a trap door, against inadvertent exposure of the medication would be redundant and thus not necessary.

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Figure 22: UPC Barcode

Pathway of the Pill

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BUDGET

Below is the anticipated cost of the project based on the prices of the individual components:

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Component Quantity Unit Price Extended Price Supplier

vacuum pump motor (donated) 1 $15.00 $0.00 dirt devil

vacuum impeller

(donated)1 $4.95 $0.00 dirt devil

Lexan 1 $15.00 $15.00 lyxnmotionPower Cord 1 $3.00 $3.00 Digikey

Actuator 1 $10.00 $10.00 DigikeyTracks with

rollers 4 $6.00 $24.00 BTI Supply

Brail dots (self adhesive) 1 $5.00 $5.00

PDA 1 $199.00 $199.00 Palm

USB Hub 1 $6.78 $6.78 TrednetData

Acquisition for USB

1 $145.00 $145.00 National Instruments

Wires & Electrical

components1 $100.00 $100.00 (Several)

Servos motor/stepper

motors6 $12.00 $72.00 lyxnmotion

Servo controller unit 1 $50.00 $50.00 lyxnmotion

Keyboard 1 $25.34 $25.34 USB Gear

Barcode reader 1 $120.00 $120.00 IDAutomation

Mechanical Components 1 $100.00 $100.00 (Several)

TOTAL (development) $875.12

TIMELINE

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CONCLUSION

Clearly the elderly population is growing. This growth extends an obvious parallel to increased medication use coupled to regiments that become more stringent and confusing. Increased medication complexity and growth expands the current market for medication dispensing devices to minimize errors in medication dosing. The products currently on the market and those described by the published patents do not accommodate the needs of the clients requesting our automated medicine dispensing device. In addition to adding a cutting component, enhanced security and a barcode reader are also necessary components of this device for added capacity to minimize errors. Our product will not only meet these requirements but also provide the product at a reduced cost compared to those currently on the market.

The optimal design is currently underway and thus a finished prototype can be anticipated in April of 2006. Once the prototype is completed, a patent can be applied for, since this product is significantly different to those described in the published patents. With its additional features, this device can be expected to compete with those already on the market, if not replace them. This research and development is possible through the funding provided by the RERC National Competition.

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REFERENCES

e-pill Medication Reminders, Wellesley, MA, 2005.http://www.epill.com

Lynxmotion LLC., Pekin, IL, 2004.http://www.lynxmotion.com

National Instruments Corporation, Austin, TX, 2005.http://www.ni.com

Parallax Inc., Rocklin, California, 2002-2004.http://www.parallax.com

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ACKNOWLEDGEMENTS

Dave Kaputa - for guidance with LabVIEW application for our device

Chris Liebler - for assistance in incorporating PDA use and proper component selection

Allegro MicroSystems Inc. - for donating four stepper motor controllers

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APPENDIX

Specifications

Electrical Parameters

Power SourcesMain AC-DC converter

Voltage splitter (resistive network)PDA rechargeable lithium battery

DisplayNumber of Characters 320x320Height ~4.5 in.Width ~3.1 in.Illumination Transflective TFT color display (65,000 colors)

Touch screenBright display for elderly and vision impairedHigh contrast

MotorsStepper motors

Quantity 2Voltage 12V

Servo motorsQuantity 4Voltage 9V

User interface roll up keyboard, possibly w/brail Accuracy ¼ tablet – 100%

Mechanical Parameters

Material PlasticCompatible with chemical composition of Medications used

Weight <20 lbsVibration minimalSize easily transportable to a home or clinical settingAnchoring/Mounting System strap or screw plateGears screw and simpleBlade

Size 1” razor bladeMaterial metal with low reactivity, possibly stainless steel

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Security Case screwed shutMedication door with child safety

Environmental Parameters

Operating temperatures 0-100° CStorage temperature dependant on medication (will research)Storage humidity airtightLight level low

Hardware and Software Parameters

PDAProcessor Intel 200MHz XscaleOperating system Palm 0S garnet (v5.4) required for LabViewRequired program Microsoft Excel

Programming Programmed in LabViewMemory 32MB (26 MB actual storage)Barcode reader Plug n Play type, output to Excel spreadsheet file

Input Parameters

Alarm silence PDA front panelBarcode data Medication name

Dose Interval Expiration datesWarning

Medication reload User operated

Output Parameters

Alarm condition User input required for medication dispensingError condition Medication jamDose/Interval Change confirmationTime stamp dose Record dose and timeMedication Near empty warning (reload)

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Purchase Order Requisitions

Additional purchase order requisitions have been approved and ordered.

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