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Participant

Join Date: Feb 2015
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College Design Project for Active Aging. Need Mechanical and Electrical Advice

02/04/2015 1:00 PM

Good Afternoon guys, I'm doing an engineering project as part of my 3rd year mechanical engineering degree, that involves designing a suitable innovative solution in aiding older people with their daily lives. As a group we came up with multiple ideas, but settled with a smart shelf design that would bring the shelf to the user's specified height.

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After some time deliberating what was the best design and screening all methods we chose the design seen in the cad model below (sorry its not very descriptive), where the basic design is that shelves sit in holders inside the cupboard and the user opens the doors which then lock in place, they specify a shelf number/name etc and the vertical shelf sliders attached via a nut to threaded bars and two stabilizer poles, move to the that shelf using light gates (probably read in by Arduino coding and software). Then the shelf is pushed out of its holder into the vertical slider once they are lined up correctly, and then the user can specify to the system (using up and down buttons) at what height they want the shelf.

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As i further researched this method it dawned on me that this is not so simple as i had once believed (or as i am put to believe after asking an electronic lecturer in my college, saying this would go into the thousands while our budget is only about €200). At first i believed that one powerful electronic motor connected to perhaps a MyDAQ component (controlling movements/motor speed and to deal with user input) and an Arduino for the light gates to read in each shelf number, and threaded bars each supported in the base and top of each door frame would be geared exactly the same and the motor would rotate these at the same speed (tolerances over multiple uses could be a problem). The stabilizers each side of the threaded bars could help in balancing the shelf between the two threaded bars as otherwise the friction might be quite off between both bars, causing unequal rotational speed and hence movement.

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I know this is quite a long winded question but i didn't know how to describe what we are trying to do. I'd really appreciate if someone could advise me in the right direction, in regards to the type of motor (what torque it would require with a load of about 15kg on the shelf), if this design is possible or am i better off going with a pulley type system with regards to the budget, what light gates i should choose and should i use an arduino to input that data or is the myDAQ sufficient?

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Please don't hesitate to ask me any related question to this, i'm not sure if i have supplied all the relevant information so if there is some variable or dimension i forgot to include that could help please let me know.

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Thanks in advance for any help!
P.S I saw this guys video on youtube and it basically describes how this method would work but im not sure if its possible for this model.

https://www.youtube.com/watch?v=hhxrNVKg0Sk&list=LLQOLrYmrpiWqoz9f4-diTfw

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#1

Re: College Design Project for active aging. Need Mechanical and Electrical advice

02/04/2015 1:20 PM

KISS.

This is far too complex for a shelf adjuster.

Take a look at your grandmother's ironing board and see how it is adjusted.

Do away with the electronics and keep it simple and mechanical.

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#2
In reply to #1

Re: College Design Project for active aging. Need Mechanical and Electrical advice

02/04/2015 1:29 PM

I wish it was all just mechanical, but it needs to be almost 100% automated because that is the aim of our project as we are aiming this project at elderly people who struggle reaching or bending down to the shelf and we don't want them to do any of the work unless its minimal and everyone can use it. Thanks for the suggestion though!

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#3
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Re: College Design Project for active aging.

02/04/2015 2:08 PM

Far to complicated, if it were me (and I am a product designer), I would simply design a set of shelves on say a chain drive (or similar) so the user pushes a single button, a drive motor turns a shaft that rotates bringing the shelves past the user one at a time. The user stops the motor when the selected shelf is at the right height. Have two buttons one for forward and one for reverse. Job done.

Think motorised tie rack, motorised rack they have in dry cleaning stores, etc but with shelves holding goods. This also greatly simplifies restocking the shelf which the elderly user still has to do also, don't forget that.

Additionally the project budget will be much cheaper, and in the real world no one will buy something that costs enormous amounts of money when something much simpler and cheaper will do the same job. A high-tech design may work in the end but if no one can afford it then the product is a failure.

This isn't an inventory pick system after all and there are only going to be a few shelves. This still isn't a simple project and there are plenty of mechanical and electrical challenges to make it a good 3rd year group project (such as shelf levelling and balancing to prevent the products falling off).

Also produce some simple designs (paper sketches, simple models, etc) and then TALK TO THE ELDERLY and ask them their opinion. You may find they have a different idea from you as to what would be user friendly to them. Include the feedback in your project as part of your development research.

Remember - there is no shame starting from scratch, so back to the drawing board !

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#5
In reply to #3

Re: College Design Project for active aging.

02/04/2015 2:29 PM

But that's too simple. You'll never impress the TA unless there is at least one feedback loop, digital display to at least four digits of resolution, WIFI and Ethernet protocols. This is a college design. The customer to impress is not the proposed nearly disabled elderly. The customer to impress is the post graduate, under employed Teaching Assistant that will be handing out the grade.

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#6
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Re: College Design Project for active aging.

02/04/2015 3:02 PM

This is a college design

This appears to be a MECHANICAL Engineering college design.

The customer to impress is the post graduate, under employed Teaching Assistant that will be handing out the grade.

Performing market research AND producing a simpler product design that is viable in the real world! I think that deserves a good grade, as long as you they show enough mechanical and electrical elements have been considered and incorporated.

This may all fall over if the group project also includes one of those pesky Engineers specialising in microcontrollers and hence complex control elements MUST be included as part of the project which requires the project to be overly complex to demonstrate concepts.

No reason however that a micro and sensors can't be included however for control of the moving shelves, safety features, programmed shelf settings (baking shelf, press selection 1), etc.

This is a college design. The customer to impress is not the proposed nearly disabled elderly.

Not true. My 3rd year University Engineering project of product developing an actual real-world product resulted in an impressed University lecturer asking me to do a favour for the University during my own time, performing real-world product development for a company which later gave me a job.

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#9
In reply to #6

Re: College Design Project for active aging.

02/04/2015 3:51 PM

CR4 really needs an agreed upon "tongue in cheek" aka sarcasm emoticon.

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#11
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Re: College Design Project for active aging.

02/04/2015 7:22 PM

It's this

Besides, I could tell you were being sarcastic but it gave me a chance to add a few other things and some more real-world knowledge and experiences I missed in my previous post that seemed relevant to this thread.

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#7
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Re: College Design Project for active aging.

02/04/2015 3:19 PM

I am elderly. In my opinion, I don't need all these complicated mechanisms and electronics. What I would really like to see is a young lady in a short skirt and a thong climb up a step ladder to get my bottle of Viagra from the top shelf.

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#12
In reply to #2

Re: College Design Project for active aging. Need Mechanical and Electrical advice

02/05/2015 12:25 AM

Am pushing 76, an active biomedical scientist (though into implants) and interested in the topic.

I agree completely with post #3 of JoAT.

One may not even remember what shelf the required item is on. Time is not of the essence (mostly). A single button that brings one shelf at a time to the chest level to help one inspect the content should suffice.

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#4

Re: College Design Project for active aging. Need Mechanical and Electrical advice

02/04/2015 2:24 PM

I agree with the others. While a clever idea, it seems rather involved.

I have been know to say "Why make it simply when it can be complicated and wonderful?", but it is usually said with tongue planted firmly in cheek.

What happens when, during the shelf shift, bottles or cans topple over?

Have you considered something more along the lines of a vertical carousel shelving system? http://storagemotion.com/autopantry/

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#8

Re: College Design Project for active aging. Need Mechanical and Electrical advice

02/04/2015 3:19 PM

As I agree with the others in the concept of the shelves rotating. I would also say with your idea the foot print of size need to operate. The rotating shelves give about twice the storage capacity.

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#10

Re: College Design Project for active aging. Need Mechanical and Electrical advice

02/04/2015 4:22 PM

Forget the Arduino and software, trust me!!!!! Just use the up and down buttons. (Make that a rocker switch. It's intuitave)

Keep your drive system SIMPLE.

Old people like a bargain far more than they do bells and whistles.

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#13

Re: College Design Project for Active Aging. Need Mechanical and Electrical Advice

02/05/2015 5:48 AM

A worm screw to activate your lift is;

1. overkill, even the senile don't put 0.83 tones of cans on their shelves

2. too complicated, who would maintain it?, who would grease it?

3. too slow, we oldies don't have long left, we won't wait.

4. If the shelf is loaded heavy at the front or back it will bind unless expensively made.

Dump the worm screws and put in two timing belts per door (inner and outer), idler shafts on the bottom and drive shafts at the top. Lock the timing belt pulleys so that the belts are always in sinc. Connect the top shafts with universal joints and and sliding splines to a common motor mounted out of the way at the back of the top shelf. A worm gear box allows standard cheap motor to run a sensible speed and also stops shelf weight driving the motor backwards. You have to put in two right angle crown gear sets but this allows you to counter reverse one shaft. One motor drives both door lifts (cheaper) also no canting of the shelf to compensate electronically. Belts inner and outer mean the shelf can be loaded off center without problems.

Control is two latching PBs ('up', 'down') with a few limit switches. Open cupboard doors and keep in open position with ball catches (trips two 'enable' limit switches). Pull out a shelf (trips an 'out' limit). You can use standard shelf slides modified so shelf sits on two cones each side. Press 'up' PB. Carriage raises from park position at bottom, collects whichever shelf is out and stops at 'top' limit switch (adjustable to individual height but must be above top shelf position). Retrieve/load goods. Press press 'down' PB. Carriage lowers and deposits shelf onto cones on shelf slide mechanism, then carries on to park at bottom.

You need to devise a method of pulling out/pushing in the shelves without bending.

You get more marks if you cite CR4 and me in the reference section of your write-up.

Good luck

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#14

Re: College Design Project for Active Aging. Need Mechanical and Electrical Advice

02/05/2015 6:14 AM

I am 75 yrs Sr.Citizen. I am glad that you have selected project for we people. I have following problems in day to day working:-

1.Changing tube light fixed near ceiling as I can not climb a stool.

2. I am worried about slipping in bathroom due skidding and breaking hip bone as my friends have already broken it.

3. While going for walk I some times loose balance as do not carry walking stick.

4.Back ache due to slip disc.

I think that is enough for your project you can select any of them.

God Bless You.

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#15

Re: College Design Project for Active Aging. Need Mechanical and Electrical Advice

02/05/2015 6:20 AM

The first question to ask is 'will it work in a practical way?', and I would suggest the answer is no.

There are several reasons, the main one being that only the lower shelf would be operable because (assuming all the shelves were used) the required shelf would have to move out far enough to clear the others before being lowered. This would seem to be a bit impractical and quite costly.

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#16

Re: College Design Project for Active Aging. Need Mechanical and Electrical Advice

02/05/2015 12:34 PM

hi, I hear your troubles. first, ur prof is probably trying to scare you, it shouldnt to too difficult to make, but he probably would like to incorporate new technologies. check this out for a screw type motor- 30bucksUS, links below, Im not sure how your design works, -are all the shelves vertical? how does anyone put anything on the shelf, does it rotate?

In selecting your motor size you need to determine the static weight amount needed to move including friction loss from compressive forces when all parts stationary and those lost by moving parts -screw screwing, hinges closing, and stopping a rotating shelf at a certain speed. then find a motor which can handle that force moment in torque, either rotating or linear -its a manufacturer specification, then get your electrical teammate to design a motor control system either through step control or H-bridge power flow, he'll need to be in the loop when selecting your motor as is it will impact his uP selection and components. Instead of using gates for height selection try IR(20$) or sound sensing(25$) for height measurement, see links, if the shelf is supposed to come out and rest above somebodys lap u could measure approx. 8in above then stop or if sits above eye level you could scan for pupil or head location and have the shelf come to rest 10in below eye level. but first I suggest some time in developing your function, both in drawing what your thinking and refining your description of your creation -including placement of key functional components and wires, try for nice and elegant, otherwise it'll come out beastie with parts that jam when your shelf comes out, sit uneven and be the size of truck!!..it's shelf that comes to you.. then eats you

oh, they used pulleys in the medieval ages, screw motors in the 1800s-today, today some use magnetic force levitation and inherent friction properties for stopping, like a solenoid or bullet train, still a motor though, just smaller more efficient

-http://www.banggood.com/JKM-42-Linear-Stepper-Motor-Trapezoidal-Screw-320MM-0_32NM-p-933434.html?currency=USD&refreshTmp=1&utm_source=google&utm_medium=shopping&utm_content=saul&utm_campaign=Industrial-us&gclid=CMCys4yjy8MCFY9ffgodNoAArA

http://www.newark.com/sharp/gp2y0a710k0f/sensor-distance-analog/dp/14N9319?mckv=sSk5WZhip|pcrid|57067535541|plid|&CMP=KNC-GPLA

http://www.robotmesh.com/vexiq-distance-sensor?gclid=CICAwZqmy8MCFYVffgodLBsA1g

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#17

Re: College Design Project for Active Aging. Need Mechanical and Electrical Advice

02/05/2015 12:40 PM

Why not have individual cabinets lower to the counter height instead of individual shelves. A bracket with arms or a drive system would mount to the wall and to the back of a cabinet. Press a rocker switch to lower or raise.

One could even use a switch actuated solenoid lock to release piston type struts to slowly lower the cabinet, and then a motor to pull it back up.

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#18
In reply to #17

Re: College Design Project for Active Aging. Need Mechanical and Electrical Advice

02/05/2015 2:30 PM

That's a pretty good idea!

Floor and/or counterspace will have to be sacrificed, but it is worthy of serious consideration.

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