The servo command should work..

Code:

Servo(D0,180) # one direction fulll

Servo(D0,1) # the other direction (if the esc supports reverse) full

Servo(D0,90) # to stop... might be a little higher or lower, experiment

#the closer you get to 90 the slower the motor or in your case linear actuator will move

Richard,

thanx for the speedy reply and code. So, can I use any digital port on the EZ-B for the 7 ESC's?

Also, being the linear actuators do not provide any feedback, will I be able to control them other than 180 or 90 degrees? Basically, if I use different degrees will the actuator always be in those actual positions every time or would they eventually drift?

Yes... Unplug from your receiver and plug it into any digital port... send the esc servo commands as in my example... it should work

Without feedback you will be unable to use position control... I am guessing the actuator has end stops instead?

Yes, the actuator just has limit switches.

Do you by chance know of anyway to create feedback for linear actuator that don't have potentiometers?

I have seen some suggestions here on the forum to add potentiometer to linear actuators that don't have them, but nobody explains how to do it.

The linear actuators that come with feedback are outrageous priced, about 4 times the price of one without it.

Not in the actuator itself but if you are using an rotation joint (axis in conjunction with the actuator), maybe you can locate a pot there?... You can feed it back to the analog ports of the ezb4..

@Rob-bot,

I been tempted to buy cheap/affordable Chinese linear actuators without feedback, asfaik it's not easy/cheap to add a potentiometer to a linear actuator.

For a 12" linear actuator the difference between feedback and no feedback is only $25.
https://www.ez-robot.com/Community/Forum/Thread?threadId=11068 (Post #10)

A few hack/ideas:

Thread


Belt with a potentiometer

What I have been thinking of doing is either mounting wheel style potentiometers to them right where the shaft goes in and out of the body or mounting wheel potentiometers to the actual part of the robot that is moving. I read a post by DJ saying you can take the controller from a standard hobby servo and make the potentiometer remote to the controller via wires and use a wheel type on the linear actuator itself and plug the servo controller wires into an H bridge.

In my case where I am using ESC's instead of an H bridge, is there a way to make a servo controller work in conjunction?

"I been tempted to buy cheap/affordable Chinese linear actuators without feedback, asfaik it's not easy/cheap to add a potentiometer to a linear actuator.

For a 12" linear actuator the difference between feedback and no feedback is only $25.
https://www.ez-robot.com/Community/Forum/Thread?threadId=11068 (Post #10)"

PTP,

I thanks for posting those vids.

As far as the prices go, the sites you are referring to are charging 3x what you will pay for the same actuators without feedback and 4x for feedback on ebay and are made by chinese companies too. I found out the hard way a few years back when I ordered one for 3x times the amount, thinking the same thing, that they must be better. Even though they are all made in China the quality is actually pretty good as I have put a couple to the test to see if they can push/pull their listed weight and they have actually exceeded their rated weights before breaking on push test, but have failed the rated weight on pull tests and this is normal as all linear actuators can push more than they can pull by design. Better quality actuators have a push/pull rating on them, where the cheaper ones do not. Those sites do not sell in large quantities the way ebay sellers do and unfortunately have to charge these high prices in order to make a worthwhile profit.

Look at string potentiometers for feedback. Relativity cheap and easy to buy or make, and mount. There are 3d plans for making them.

@Rob-bot:
I searched the Ebay with $50 i can get 12" linear actuator but no feedback.
I still think is too risky to spend $50 and then spend extra bucks to add the feedback without guarantee of success.

@AndyRoid:

Good tip!

I found a DIY version: https://www.thingiverse.com/thing:1926226
(Potentiometer: $15, retractable: $6 plus shippings and 3d printing)

or a kit version: https://www.andymark.com/product-p/am-2674.htm ($40)

Yeah, I've seen that article before and would like to try it but dont have a 3D printer yet. I am going to get one, but need to know the minimum size required to print the INMOOV android. I have also been looking at linear potemtiometers, which come in different sizes.