A little help, or guidance should i say?

[Nayyi]

Hi, im new here. Just visited this site and i found it amazing that people here help others eventhough the projects are for academics. I would like to ask for help for my elevator simulation project. the elevator is suppose to run by using a stepper motor. yet, as the cart reaches the floor you have pressed, the door must simultaneously open up, like a real elevator. The one that i will be building is needed to be 4-storey, no weighs will be applied to the cart, only the cart itself will be carried up and down. I have read the other posts here, and it says you would be needing limit switches, other says use optical sensors. I have merely no idea where to start from, can anybody help me...

a link below is the animation i have made on how the elevator should behave.
**broken link removed**

Note: no programmable logics may be applied.

 

[penoy_balut]

To make it simple, you can use limit switches and relays or limit switches and logic gates.

 

[ClydeCrashKop]

I would use an Allegro stepper driver chip to match your motor. It needs step pulses that can come from a 555 timer chip. Maybe an LM339 quad comparator chip wired like a bar graph (voltage dividers) to determine and supply the direction signal. Optical sensors won’t need de-bouncing but may need conditioning. I couldn’t see the animation. Do you need another stepper for the door?

 

[Nayyi]

oh well those ideas came to me too, using relays, limit switches but i tend to stay away from optical sensors, they are way too moody. can you guys help me build the circuit?

@clydecrashkop
needs flash player plugin to play it, uhm for the door i will just be using a reversible dc motor using relays again to reverse the direction the motor rotates, it would be of great help if you guys can help me build the circuit...

 

[penoy_balut]

application like that does not need stepper motor, a DC motor is enough for raising/lowering the cart, a simple mechanical switch for sensing cart presence in every level should be enough

 

[Nayyi]

but it is required for us to use stepper motor ^_^

 

[Hero999]

So this is for a school project?

Whilst we enjoy helping people; in order to help you we need to know how far you've progressed. Please post what you've already done, including any ideas you've had. If you need help that your lecturer should have provided, please tell us (and your lecturer) what you found was lacking. It is not right if you manage to attain a high grade from the help we have provided if your lecturer is negligent; it will make them appear to be better than they really are and put you at an unfair advantage to your classmates.

 

[richardv2]

Elevator

I teach a class where the final project is often an elevator using a Programmable Logic Controller. (Laddrer logic to run the elevator.)

In several years, I've only seen one that worked fully, and one that worked marginally. The problem is almost always the same. Not the electronics, not the programming, but the mechanics. So be warned this is the hardest part, if you do not have high mechanical aptitude.

My observations...

The second most often cause for failure is the use of stepper motors. Students don't realize that typical small stepper motors are very low torque devices. They will usually not lift the weight of the container. I did see one clever arrangement where the container had a counter-weight behind the elevator to offset the weight and make the job easier for the stepper motor.

The most successfull mechanical solution I saw was achieved by attaching the container to several really long, thin threaded shafts. A motor turned the shafts. Bolts on the shafts moved up or down depending on the direction. The container was connected to these bolts.

As to floor sensors, both optical and mechanical limit switches all seem to work fine, so I'd say go with switches if you are a novice and want the easiest solution, or try optical/IR sensors to play with that technology if you wish.

I'll probably put some photos of a good elevator on www.picrobots.com soon, and you can email me at rvannoy@itt-tech.edu if you have more questions.