Activating Levers - Motor or Linear Actuator

Hi,

I am just starting out with Arduino and would like to start my very own project.

It would like to create something that would pull down on a lever/door handle and nothing else.

It would be a movement in a straight line.

I have done some research and it seems that what I need is a linear actuator.

Am I on the right track, will a linear actuator have enough strength to be able to push down on a common door handle?

Thank you and any help is greatly appreciated.

A linear actuator or geared motor and lead screw would be my choice. Measure the force that it takes to pull the lever with a fish scale and note the distance required. Those are the 2 most important things to know to choose or build an actuator. And the available supply voltage.

Am I on the right track, will a linear actuator have enough strength to be able to push down on a common door handle?

Yes, they come in different sizes/strengths/speeds.

How much force does the lever need? You can check it with a pull-gauge (or with weights if it works by pulling down). You'll probably want to use about double the required force to allow for "sticking" and so you don't over-stress the motor by running it at it's maximum.

Alternatives to a linear actuator are a a belt & pulley or worm/screw. These are common ways of converting rotational motion to linear motion. You'd have to do some calculations convert torque into linear force.

It would like to create something that would pull down on a lever/door handle and nothing else.

Typically, you'd replace the lock/latch with a [u]solenoid lock[/u] rather than rigging-up something to turn the handle/lever. [u]Here's are some[/u] for an entry doors.

mgsolid2010:
Am I on the right track, will a linear actuator have enough strength to be able to push down on a common door handle?

Of course. They can really powerful. A linear actuator could easily lift your door (even if it's really really heavy solid steel door: just go for a hydraulic cylinder, like they use to move the bucket of an excavator). Just get one that's got the force, displacement and speed needed for your project.

At some point you will need to think about how you will know that the handle is pulled far enough or released (limit switches?).

I wonder would a servo be suitable - it would make a lot of things much easier.

@mgsolid2010, can you post a diagram with dimensions showing what you want to do?

...R

Thanks all for the feedback - greatly appreciated.

@Robin2 I will post a picture of the lever that I would like to operate very shortly.

I though I had found a decent actuator, though from what I have seen, they may be too slow. This is the one I was I considering to get, but it is far too slow.(https://www.ebay.co.uk/itm/152577879468?var=451989176312)

What sort specification should I look for to get an actuator to perform as below or an high performing motor?

HI,
Look for electric auto door lock actutors, ebay has them, most are a motor and rack drive, rather than a solenoid type actuation.

Tom... :slight_smile:

TomGeorge:
Look for electric auto door lock actutors, ebay has them, most are a motor and rack drive, rather than a solenoid type actuation.

One thing to consider with that type is the throw is in the neighborhood of one inch.

Where is this device going to be sitting when it’s pushing down on the door handle? Is it bolted to the door?

If it’s a floor-standing robot, does the door open towards the robot? (difficult to back out of the way while holding the door) or does it open away from the robot? (now your robot is in the way of you going through the door and it can’t reach the door to close it behind you.)

MorganS:
Where is this device going to be sitting when it's pushing down on the door handle? Is it bolted to the door?

If it's a floor-standing robot, does the door open towards the robot? (difficult to back out of the way while holding the door) or does it open away from the robot? (now your robot is in the way of you going through the door and it can't reach the door to close it behind you.)

It will be bolted to the door

Are you allowed to do more than bolting to the door? An electronic lock is easy to buy and easy to interface to an Arduino. It doesn’t have to move the handle.

Ideally I wanted to re-use the actuator later and just wanted to experiment on understanding how it works.

The weight required to activate the handle/lever is up to 5kg and travel length is around 4 inches.

Though I have read somewhere that linear actuators can suffer from overheating issues, is this also the case for the slightly higher end ones? This would be interesting from an automation perspective.

Has anyone experienced this issue?

linear actuators can suffer from overheating issues,

If they are used outside their design limits or poorly designed for the job, sure. I have seen actuators that have a duty cycle specified, just don’t violate the spec and you should be OK.