Linear motion project

[gkhn]

Hi,

I am building a project which consists of the following requirements.

• Two linear motion system to lift and push weight
• Synchronization of two system (they can be lifted at the same time or independently (manual mode) )
• Collision detection(if the linear system is under pressure or forced, the system needs to stop)

I have got a few options:
1- Lead screw( I want to avoid this if possible)
2- Linear actuator motor( http://www.ebay.com/itm/DC12V-600mm-Linear-Actuator-Motor-Multifunction-24-1500N-For-Autos-Chairs-Boat-/272123036533?hash=item3f5bcc0375:g:8RUAAOSwv-NWapVn)
I am not sure if this also has a linear lead screw arrangement
3- Magnetic linear motion. This will be ideal but the price can be too high.
4- How can I synch two linear motion systems together? Lasers? Sensors?

Are there off-the-shelf solutions that will do these requirements?

Thank you.

[Robin2]

It sound like you need to make decisions about the mechanical system first and I suspect you will be more likely to get advice about that elsewhere (though I don't have any suggestions).

...R

[cbrum11]

Without a more detailed description of what you're trying to accomplish, it's really difficult to give advice. I also second Robin2... seems like you're still in the mechanical stage of things and not quite to the control stage yet.

With that said...

Power screws was my first thought. Why are you opposed to using them?

There's also the option of regular motors with fancy gearing directions.

But as stated earlier, it's hard to give any real advice without more specific information about how and what you want to accomplish.

-Chase

[gkhn]

Thanks for your replies.

I have an existing system with a weight & a counter weight attached to it. It can be moved up and down manually with ease.

I need a reliable linear system to lift this up and down automatically controlled by arduino.

I would appreciate some suggestions and options from you guys.

Robin2:
It sound like you need to make decisions about the mechanical system first and I suspect you will be more likely to get advice about that elsewhere (though I don't have any suggestions).

...R

Power screws need regular maintenance and lubrication. I had so much trouble with them over the years. They get stuck really easily.

Having said that, I am open to any product/solution that you may suggest.

cbrum11:
Without a more detailed description of what you're trying to accomplish, it's really difficult to give advice. I also second Robin2... seems like you're still in the mechanical stage of things and not quite to the control stage yet.

With that said...

Power screws was my first thought. Why are you opposed to using them?

There's also the option of regular motors with fancy gearing directions.

But as stated earlier, it's hard to give any real advice without more specific information about how and what you want to accomplish.

-Chase

[cbrum11]

I have an existing system with a weight & a counter weight attached to it. It can be moved up and down manually with ease.

Are you saying you just want to add an automatic mode to your existing system? Something that would move the weight and counterweight without human input force?

If this is not what you're saying...

How much weight needs to be lifted and moved?

How often does this weight need to be moved?

How far in each direction do you need to move the weight?

Are you trying to move around objects or is it a clear path?

What size are you trying to keep this device?

Will the device be functioning inside or outside?

What shape is the object that needs to be lifted?

...These are the types of more detailed answers we need before we can help.

[TomGeorge]

Hi,
I think we need to know what the complete application is that you are trying to describe.

Tom.....

[cbrum11]

Hi,
I think we need to know what the complete application is that you are trying to describe.

Tom.....

Yea...

What Tom said

[gkhn]

Yes. Automatic system to move it up and down. It already can be moved up and down as it has existing rails etc..
All I need is to attach a linear motor/rail system to the weight to.

Answering your questions.

How much weight needs to be lifted and moved?
I have the weight and the counter weight. They both weigh at about 40 kgs.

So I assume I don't need to get a heavy duty one as the counter weight will help the linear system.

How often does this weight need to be moved?
Pretty often. It needs to be moved up/down 100 times a day at least

How far in each direction do you need to move the weight?
About 1.50 meters max from bottom to top, and top to bottom. It needs to be flexible from 0 - 1.50 meters. The more resolution is better.

Are you trying to move around objects or is it a clear path?
Clear path but I need a collision detection so that if it hits something in the middle of moving up/down, it needs to stop.

What size are you trying to keep this device?
Doesnt matter.

Will the device be functioning inside or outside?
Inside.

What shape is the object that needs to be lifted?
Rectangle

cbrum11:
Are you saying you just want to add an automatic mode to your existing system? Something that would move the weight and counterweight without human input force?

If this is not what you're saying...

How much weight needs to be lifted and moved?

How often does this weight need to be moved?

How far in each direction do you need to move the weight?

Are you trying to move around objects or is it a clear path?

What size are you trying to keep this device?

Will the device be functioning inside or outside?

What shape is the object that needs to be lifted?

...These are the types of more detailed answers we need before we can help.

[Robin2]

I think you need to post a diagram of your machine to help us understand what you are saying and what options might exist for powering it.

I suspect the collision detection will be the most complex part.
How might a collision happen? Can those circumstances be avoided?

...R

[Grumpy_Mike]

The bit I don't get is, is there independent movement as well as the movement you want to make?
While the weight and the counterweight cancel out the momentum and inertia don't. Therefore you need a hefty motor to overcome that.

[gkhn]

I have just drawn a simple illustration of the existing system.

It basically shows the counter weight (front and rear view).

The rectangle area can be moved up(up to 1.7meters from floor) and down & I am interested to automate this.

[gkhn]

Please see the diagram of my machine.

The collision detection can be avoided by implementing a warning system. "Beep beep beep, the rectangle will be moving in 3 seconds. Stay within the safe zone of the device"

But accidents can happen.

A person can walk underneath and it will crash their head down...

So if an unusual counterforce is detected, i want it to stop.

Robin2:
I think you need to post a diagram of your machine to help us understand what you are saying and what options might exist for powering it.

I suspect the collision detection will be the most complex part.
How might a collision happen? Can those circumstances be avoided?

...R

Yes it can be moved manually independent( a person pushing it down) or it can be automated(automated linear motion driven) which I am trying to accomplish.

So if I use a power screw, how can i push it up/down manually?

Maybe a chain along the side on the stand and the motor attached on the rectangle load. Then when the motor turns, the teeth will contact the chain on the stand which will move it up or down.

If it is manual, the motor will be deactivated and it can still move up and down(motor will turn teeth will turn on the chain freely.

Grumpy_Mike:
The bit I don't get is, is there independent movement as well as the movement you want to make?
While the weight and the counterweight cancel out the momentum and inertia don't. Therefore you need a hefty motor to overcome that.

[Robin2]

Image from Reply #10 so we don't have to download it. See Image Guide

...R

[TomGeorge]

Hi,
So you will be moving in 2 axes, Vertical or Y axis, LIFT,which your diagram shows.
Plus Horizontal or X axis, PUSH, which your diagram doesn't.

That would explain this;

• Two linear motion system to lift and push weight

You seem obsessed with linear.
Why don't you drive the pulley at the top of your Y axis with a geared motor and encoder?
Using a toothed belt, or chain to drive the LOAD up and down so that you have no slippage,
Your X axis could be the same thing, geared motor and encoder. toothed belt, or chain, but mounted horizontally.
The encoders will give you position information for your automated system control.

OR use stepper motors, this all depends on the drive power needed.

Look at how the Horizontal plane bed of a 3D printer works.
Or Look at how a mechanical plotter works, all in 2D with X - Y axes.

What is your electronics, programming, arduino, hardware experience?
Is this a school/college/university project?

Tom...

[Robin2]

gkhn:
Please see the diagram of my machine.

It looks like there is a rope or wire running over a pulley. If so why not drive the pulley with a suitable motor.

A person can walk underneath and it will crash their head down...

So if an unusual counterforce is detected, i want it to stop.

Computer code should have NO part in preventing that risk. There should simply be a barrier around the machine.

Detecting a counterforce would not prevent injury - the injury would already have happened.

...R

[TomGeorge]

Hi, again.

I echo Robin2's concerns about safety, use barriers to prevent access to the area during operation.

You still have not told us the application, are you making an small automated warehouse storage system or a home automated library storage system for your DVDs?

If safety is involved, then tell us all.
If safety is that important, we need the full storage so we can advise you correctly.
If it is a commercial system you are building, then go to the equipment suppliers for professional industrial safety advise, I do.

Tom....

[gkhn]

Thank you for your replies and interest in the subject

Vertical only (LIFT DOWN AND LIFT UP) at this stage.But I will be thinking to move it horizontally as well..

I am not obsessed with linear.

Yes I also thought replacing the existing pulley which is probably the best solution.

Unfortunately, I cannot replace the pulley with a geared motor. I am not allowed to modify the existing pulley system. Only exterior mods I can do. Besides it is time consuming to replace the pulley and fit something suitable.

If I have a chain bolted on to the stand vertically and a motor attached to the load, will I be able to drive this without any drawback? Is there anything I need to be concerned of if I choose this route?

I have some electronic and programming experience and mechanical experience.

It is just a personal project.

TomGeorge:
Hi,
So you will be moving in 2 axes, Vertical or Y axis, LIFT,which your diagram shows.
Plus Horizontal or X axis, PUSH, which your diagram doesn't.

That would explain this;You seem obsessed with linear.
Why don't you drive the pulley at the top of your Y axis with a geared motor and encoder?
Using a toothed belt, or chain to drive the LOAD up and down so that you have no slippage,
Your X axis could be the same thing, geared motor and encoder. toothed belt, or chain, but mounted horizontally.
The encoders will give you position information for your automated system control.

OR use stepper motors, this all depends on the drive power needed.

Look at how the Horizontal plane bed of a 3D printer works.
Or Look at how a mechanical plotter works, all in 2D with X - Y axes.

What is your electronics, programming, arduino, hardware experience?
Is this a school/college/university project?

Tom...

Steel wire running over pulley.
Thanks for your suggestions but I cannot replace the pulley as I explained above.

Would it be at least stop the motor once such force is detected to prevent further injury?

Robin2:
It looks like there is a rope or wire running over a pulley. If so why not drive the pulley with a suitable motor.

Computer code should have NO part in preventing that risk. There should simply be a barrier around the machine.

Detecting a counterforce would not prevent injury - the injury would already have happened.

...R

[TomGeorge]

Hi,

If I have a chain bolted on to the stand vertically and a motor attached to the load, will I be able to drive this without any drawback? Is there anything I need to be concerned off if I choose this route?

It will work, or a rack with gear on the motor, a chain might have some backlash but if you can tolerate it, the chain would be the quickest and easiest to implement.
Backlash could be minimised if the chain went over/around the drive motor pulley, instead of using the chain like a rack.

Tom...

[gkhn]

Thank you for your advice regarding the safety.
Well noted.

You could say it is an automated equipment used in medical industry

TomGeorge:
Hi, again.

I echo Robin2's concerns about safety, use barriers to prevent access to the area during operation.

You still have not told us the application, are you making an small automated warehouse storage system or a home automated library storage system for your DVDs?

If safety is involved, then tell us all.
If safety is that important, we need the full storage so we can advise you correctly.
If it is a commercial system you are building, then go to the equipment suppliers for professional industrial safety advise, I do.

Tom....

[gkhn]

Thanks for this. Really appreciate it.

Could you please draw a digram of the the chain going over the drive motor pulley or an example picture somewhere online? I dont quiet understand how the linear motion would work with your suggestion

TomGeorge:
Hi,It will work, or a rack with gear on the motor, a chain might have some backlash but if you can tolerate it, the chain would be the quickest and easiest to implement.
Backlash could be minimised if the chain went over/around the drive motor pulley, instead of using the chain like a rack.

Tom...