Options Considered:options.doc
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ECE 403 Senior Design II
Options Considered October 21st, 2005
Automated Medicine Dispenser
Patrick Beaver Rachel Dorry Dan Bowen
Group #253 – Dr. Kavasseri
Introduction:
The idea of an automated medicine dispenser is a concept which has been developed in many different ways. The variety of dispensers available ranges from a box with presorted compartments and a basic timer to other dispensers that can automatically count and dispense any amount of pills. Some of these dispensers do not focus on the features that our clients would need. Our clients would like to see this dispenser be basic enough for a person with cognitive disabilities but also have technological features for the staff.
Our client for this project is SVEE Home. SVEE Home is a group home for people with cognitive disabilities such as Down Syndrome. The lifestyle of the residents is as independent as possible while having a staff member available at all times. This project should help to improve the efficiency of the daily activities of SVEE staff as well as gradually increase the resident’s independence in this area. Our plan to achieve this goal is through a user friendly interactive medicine dispenser.
Options for each Block:
Power Block:
• Option 1: For the power source for our project we intend to use a standard plug in as well as a battery backup system. The back up battery system is going to use a set of rechargeable batteries. The back up system that we would like to use is similar to that of a cellular telephone or a laptop computer. When the dispenser is plugged in the batteries would charge and when power is disconnected the unit would run off of the batteries. The advantage to this set up is having an efficient power source which is reliable in all circumstances such as power outages. However having the primary source being a plug in based unit limits the mobility of the device. • Option 2: Our second option for the power supply is just using a battery set up. This is a great option if you needed the medicine dispenser to be portable and compact for on the go use. A portable dispenser is very practical for the user because he or she would be able to travel with the dispenser as well as having the convenience of a reminder to take his or her pills. Even though the idea of a compact and mobile dispenser is a good one, we feel that some very important and necessary features would be compromised. First of all, the cost of the batteries will make the device seem very inefficient to the consumer. Secondly, the battery system does not have a back up power source which would prevent the loss of data. • Chosen Option: We have decided to use Option 1 based upon the design criteria and the overall reliability of the system. It is imperative to the consumer to have a system that will not lose power. The basis of the device to make sure that the consumer is taking medicine in appropriate dosages at proper times. Choosing Option 1 will prevent the device from losing power which will cause the system to reset information and could result in the patient missing doses of medication. For the safety of our consumers, we need to make a device that will be reliable in all situations. Another important reason for choosing Option 1 is the efficiency of the device. Having a plug in source will eliminate the cost of batteries to the consumer. Also, having the battery back up system recharge itself will allow the user to feel secure in a reliable back up system.
Microcontroller:
• Option 1: The PIC16F876a is a microcontroller that is familiar to all three of us. This processor will be easily accessible and is capable of perform the tasks needed for our project. The microcontroller has a low power consumption (< 2mA) which will help when the device is using the battery backup system. • Option 2: Our second option is the Phillips P89LPC930. This an 8 bit microcontroller with a two 16-bit counter/timers and 256-byte data RAM. The operating power range is 2.4V to 3.6V. One advantage to using this microcontroller is that it has a Real-Time clock that can also be used as a system timer. However, none of us have used the processor before. • Option 3: MC68HC11F1 was our third choice. This processor is comparable in price to the PIC16F876a. One feature that we like about this microcontroller is the power saving STOP and WAIT modes. This also has an Enhanced 16-bit timer. We did find that this processor has an 8-bit A/D converter while the PIC16F876a has a 10-bit A/D converter. • Chosen Option: We decided to use the PIC16F876a for the main reason that it is the only processor that we have any experience with. All of us have taken the ECE 376 Embedded Systems class that uses the PIC. Also, the Electrical Engineering Department already has the bootloader for this processor.
Dispensing:
• Option 1: We have considered many different types of mechanisms for the dispensing of the pills. One idea was to have a device that will count and sort the pills. This would have a funnel shaped apparatus that would align the pills one on top of the other at the bottom of the funnel. At the tip of the funnel, there would be a flap that would have a timed opening and closing which would release one pill at a time using gravity to drop the pill. This idea would eliminate presorting by the staff or nurse. However, we feel that this idea leaves a lot of room for error. This flap does not take into consideration the different sizes and shapes of pills. Also, there is no way to know when the flap is lodged open. The design of the funnel and flap would require the size of the device to be much larger than planned. • Option 2: The second idea was to have a presorted method. This method would decrease the error that could be made by the device. This option would have 3 compartments for each day of the week. The timer would release the hatch for one compartment of pills and this would distribute the pills through a slot. This idea was space saving. This option increased the need for different mechanical mechanisms in the device. Also, we were not sure how we would have the compartments reset with each weekly fill. • Option 3: The third idea was a circular, rotating presorted device. This would have pie shaped compartments that would be sorted in advance. A motor will rotate the sectioned device over a dispense aperture which will release one dose of pills at a time. The sectioned device will have 24 sections. 21 sections will hold a week supply of pills at a maximum of three doses a day, 7 days a week. One remaining section will be a neutral section that is over the slot when pills are being filled. The only disadvantage is having two extra compartments. • Chosen Option: We have decided to implement Option 3. This Option seems best suited for our design criteria. The rotating dispense aperture design greatly reduces the risk of mechanical malfunction. This is important because proper operation is vital to the reliability of the device. The presorted method reduces the risk of the patient overdosing or missing doses. The single dispensing hatch makes the process more efficient.
Motor:
• Option 1: The first motor we looked at was a 5 volt dual direction stepper motor. This motor could go both forward and backward. The step angle of this motor is 7.5° which allows us to have 48 compartments for pills. The size of this motor is 5mm x 66.7mm x 6.35mm. This motor does most the things that we are looking for; however, having a step angle of 7.5° makes our compartments much smaller. Also, we do not need this device to be dual directional. The fact that this motor runs on 5 volts could make the motor burn out easier. . • Option 2: The second motor is a 12V stepper motor. This motor is 42mmx 49.5mm x 3mm. Even though this motor is still relatively small, we are looking to keep the size of the motor as small as possible. Also, the step angle of this motor is 3.6°. Having a step angle of 3.6° makes the motor do more work to get the proper compartment capacity. It would take the motor 2 or 3 steps instead of 1 or 2 to get the compartment lined up to drop all of the pills. An advantage is the fact that this motor is rated at 12 volts, and should be able to supply enough power to work the mechanisms properly. • Option 3: The last choice is a 12V stepper motor as well. This motor has a step angle of 15° and is ideal for our rotating compartments. This will allow for us to have 24 compartments, which was our original idea. This motor is 26mm x 34.9mm x 2mm. This motor may be a little larger than a couple other ones we looked at, but still smaller than option 2. • Chosen Option: We found that Option 3 was the best choice for us to make. Option
