Author Topic: New Project (Read 5147 times)

RoBoTicS · « **on:** January 15, 2009, 07:24:29 AM »

Hey everybody I was thinking about somehow putting a sensor on my bedroom door and when I walked up to it it would open. Does this seem possible or is it out of my league also how would I control it?

Thanks,
Zach

airman00 · « **Reply #1 on:** January 15, 2009, 08:05:01 AM »

Simple to do

Get a sonar sensor and get the range of an object approaching your door , once the range is close enough then open the door.
By opening the door , do you mean unlocking it? or swinging open the door so you can walk in?

RoBoTicS · « **Reply #2 on:** January 15, 2009, 09:26:30 AM »

I wont have no lock or anything like that on it. It will swing open. Then once I make it though the door I want it to close shut.

I am guessing I will need a micrcontroller then hook the sonar sensor up to it and program it.

What will the door be moved with?

airman00 · « **Reply #3 on:** January 15, 2009, 09:33:23 AM »

Quote from: RoBoTicS on January 15, 2009, 09:26:30 AM

What will the door be moved with?

Thats the problem. I would go with some pulley system thats turned by a beefy motor ( controlled through relays by microcontroller)
Basically have a motor wind a rope which is connected to the door and it pulls open the door. Then the motor unwinds the rope and the door closes ( this assumes that the door closes by itself because of gravity OR there is a spring there that pushes the door shut and the motor pushes overcomes the spring force to shut it when opening the door.)

RoBoTicS · « **Reply #4 on:** January 15, 2009, 09:50:33 AM »

Okay this is what I am going to do.

First I am going to hook a spring at the top of the door to the outside door frame. So when I have the pulley on the other on the wall and connected to the door with a string. It will be activated with a sonar senser then it will stretch the spring, once it is open I will walk through then the pulley will retract and let the string out and the spring will go back to its normal stage closing the door at the same time.

The hardest part for me will be programming it.

Also I will probably use a strong servo instead of a motor

airman00 · « **Reply #5 on:** January 15, 2009, 10:20:02 AM »

Quote from: RoBoTicS on January 15, 2009, 09:50:33 AM

Also I will probably use a strong servo instead of a motor

I doubt a servo will have enough torque.

This is what you will have to do :
Calculate the spring force of the spring : Force of Spring = kx , where k is the springs constant and x is the spring's extension
Then you need to calculate how much force is needed with the pulley - you'll have to look at pulley equations
Then you'll have to translate how much force the pulleys need into torque of a motor.

RoBoTicS · « **Reply #6 on:** January 15, 2009, 06:53:04 PM »

Okay
I will just have to find a pulley and a spring somewhere around the house or I will go to the hardware store.
I will post up again if anything goes wrong

izaktj · « **Reply #7 on:** January 15, 2009, 07:02:36 PM »

Good luck mate

want2learn · « **Reply #8 on:** January 16, 2009, 01:10:44 PM »

Have you seen those soft close door things that mount to the top of a door and have a jointed arm assembly?

They do a motorised version. When I was at school (when dinosaurs roamed the earth

) a few of the doors had them, they were for disabled access.
I think you could find one of them easily in a salvage yard and convert it for your needs.

If you can't find a motorised one a geared down hobby grade R/C drive motor would suffice for the drive. You may need to use an H-Bridge with limit switches to prevent over-travel

RoBoTicS · « **Reply #9 on:** January 16, 2009, 07:38:47 PM »

Quote

Good luck mate

thanks

Quote

Have you seen those soft close door things that mount to the top of a door and have a jointed arm assembly?

Thats a good idea I will check that out

Metal Slug 2 · « **Reply #10 on:** February 08, 2009, 03:32:23 PM »

Hey

Ive always been interested in an idea like this. when i was 10 i built something like it...except everything was controlled from my bed, by strings (yes i did have to screw in 0-ring screws into my walls and ceilings, and yes my mom freaked out..but i still got to keep it

). i had everything controlled by strings. Even a bunch of boobie traps! (one would drop a bunch of jacks on your head, another roll bunch of marbles at your feet..etc.) I would simply pull the corresponding sting to make a boobie trap or other device work. But now, with the extremely useful help of this website, i think i can automate everything!

Quote from: airman00 on January 15, 2009, 09:33:23 AM

Thats the problem. I would go with some pulley system thats turned by a beefy motor ( controlled through relays by microcontroller)

Ive always wondered about that, i could never picture how you would hook up a high power consuming motor to a small MCU. apparently through 'relays' ...could someone please enlighten be on what they are and how to go about making or doing a relay type thing for lets say the $50 robot. or possible a couple resources?

Thanks

frodo · « **Reply #11 on:** February 08, 2009, 03:51:56 PM »

wow, metalslug, you sound creative. making a whole pulley system at 10. thats really cool.

Razor Concepts · « **Reply #12 on:** February 08, 2009, 05:49:50 PM »

Metal Slug what state do you live in? I heard of a story of a guy who got accepted into my school because he built a pully system to open a door.

frodo · « **Reply #13 on:** February 08, 2009, 05:53:08 PM »

someone got accepted into a school for building a pulley system? what school is this?

Razor Concepts · « **Reply #14 on:** February 08, 2009, 05:54:45 PM »

TJHSST - a magnet high school, you have to apply to get in.

frodo · « **Reply #15 on:** February 08, 2009, 05:55:47 PM »

magnet high school?

Metal Slug 2 · « **Reply #16 on:** February 08, 2009, 07:54:35 PM »

Quote from: Razor Concepts on February 08, 2009, 05:49:50 PM

Metal Slug what state do you live in? I heard of a story of a guy who got accepted into my school because he built a pully system to open a door.

I don't live in the states, I'm your neighbor to the north

I live in Ontario, Canada.
I'm also in Gr. 11 now, so University will be the next step.

Quote from: frodo on February 08, 2009, 03:51:56 PM

wow, metalslug, you sound creative. making a whole pulley system at 10. thats really cool.

Thanks. All my contraptions came in quite useful (although they were completely unpractical because you could only operate them from my bed). For example if my younger brothers would walk into my room and i would be for some reason lying on my bed, and i didn't want them in their, i would make them leave by the simple pull of a string which would set off an elastic band shooter or swing a large rubber ball into their face. It was very simple stuff though. Ive since build bigger and better contraptions and things...

cooldog · « **Reply #17 on:** February 08, 2009, 07:57:41 PM »

Quote from: Metal Slug 2 on February 08, 2009, 07:54:35 PM

I live in Ontario, Canada.

me to

Admin · « **Reply #18 on:** February 15, 2009, 06:58:56 AM »

Quote

Ive always wondered about that, i could never picture how you would hook up a high power consuming motor to a small MCU. apparently through 'relays' ...could someone please enlighten be on what they are and how to go about making or doing a relay type thing for lets say the $50 robot. or possible a couple resources?

Don't use a relay, use a MOSFET. A simply I/O pin on a microcontroller acts as the on/off switch, while the MOSFET handles the huge amounts of power.

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Author Topic: New Project (Read 5147 times)