ZWave or Zigbee Controller for Linear Actuators? (Automated A/V Cabinet project)

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(Kyle Davis) #1

I’m looking to automate some cabinet doors, and this will be my first DIY project. I understand that I should rely on linear actuators for the mechanical half of the task, and as I understand it, I’ll need a power supply connected through a couple of relays: one wired to drive the actuator forward and one to reverse it. But the part I haven’t figured out is how to control that in a way that I can trigger from SmartThings.

Since most of these actuators appear to be driven by 12V DC, I assume the ideal scenario would be a ZWave device that also accepts 12V power and has at least two signal outputs, one for each relay. Or maybe there is a ZWave device that has the two relays built in? What am I looking for here? Can someone point me to a controller you’ve successfully integrated with SmartThings to control a linear actuator? Better yet, a link to the actuator and all the other pieces to build the whole thing?


#2

People have done this kind of thing on multiple size projects. I don’t recall one with cabinet doors, but that will be cool. :sunglasses:

There’s a prebuilt product for chicken coop doors called coop boss which is very nice, but has a lot of features that you aren’t likely to need. Still, it’s worth knowing about.

The ones which are likely to be likely to be a closer fit are probably the people who have automated a pet door. Those have all been DIY projects, and there have been a couple of different versions.

(there’s also at least one project with motorized windows, but because of the glass and the need to be able to stop the window in various positions I don’t think those are going to be as applicable for your needs as the pet door projects.)

All of that said, remember that there are safety issues with cabinet doors also. Not as bad as a door that a person or animal actually goes through from both sides, but still real. You don’t want to catch someone’s finger in the door. so that’s just something to think about.

(I myself am quadriparetic so I do pay attention to projects like this. At my house, we ended up just teaching my service dog to open the cabinet doors as it was less expensive all around given that I already had the dog. :sunglasses::dog:)

OK, as far as finding these project reports… There quick browse lists in the community – created wiki for projects of various types. As it happens, both the chicken coop project and the pet door projects are on the list marked “pets.” In the project report section of the quick browse lists.

Again, I think the dog door projects have the most applicable equipment, you may even be able to downsize from that depending on the type of doors you are using.

http://thingsthataresmart.wiki/index.php?title=How_to_Quick_Browse_the_Community-Created_SmartApps_Forum_Section#Quick_Browse_Links_for_Project_Reports.2FQuestions

Good luck, I look forward to hearing more about your project in the future!


(Alex) #3

@KyleDavis - You can find all available zwave devices by browsing the zwave alliance pages at:

http://products.z-wavealliance.org/regions/2/categories

This will not include viable Zigbee options though.

You are not providing enough information on the linear actuators to define what type of relays are needed however there are a number of zwave devices that have 2 relays switches in them.

One that you should check out (as it seems to match the few requirements you provided):

FortrezZ MIMO2+

User Manual:

Do the actuators have some way to determine end (where to stop for open and close) points? Do they sense blockage/resistance so they don’t cause harm or break forcing their way? Speed control? Do you have a way to prevent a cupboard door opening while an obstacle is approaching (kid/dog/other person walking by a cupboard door that is opening)?

I am really curious to see where this project leads you! Keep us posted!


(Kyle Davis) #4

If I don’t provide enough info on the electrical/hardware side, just assume it’s my ignorance there more than anything. I’ve been writing software for 20+ years and can build SmartApps and Device Handlers all day long, but I’m relatively inexperienced on the electrical and hardware side except for a few past side projects.

What more info do you need besides the 12V input rating on the actuator? Something like this is what I was thinking…

After a bit more research this morning, I think I could use the MonoPrice ZWave Curtain Module as a controller. If I understand correctly, I would need two relays, but I am lost on exactly what type I would be looking for. I would wire the signal line of the relays to the open/close lines on the curtain module. Then I would need 12V DC power for both the curtain module and both relays. Does that sound about right?


(Alex) #5

No worries, all I meant was that without more info, any suggestions you get are just guesses that need to be fully vetted out.

At a quick glance it appears what you found will work however you need to add 2 SPDT relays that can handle 10A @ 12V at least. The control module can only switch 100mA so it is meant to control the appropriate relay for the intended load. The actuator you found requires 6.5A (6500mA) - always give yourself some buffer - that is why for this device I would go with at least 10A. This applies to your power supply as well… 10A @ 12V should be enough to actuate this device. If you plan on powering more than one actuator at the same time, the power supply needs to handle combined power (plus safety margin).

I am assuming the actuator’s direction is controlled by reversing polarity - in which case - you can wire it up like this:

Wiring it this way will allow you to reverse polarity by switching one or the other relay. The motor will only ever run in one or the other direction when the motor’s terminals are connected to opposing polarities. If the motor is connected to minus or plus on both of its power terminals it will simply not move.

Only caution is to be careful not to wire it in a way you will cause a short between plus and minus.

The actuator you found seems to have a non adjustable internal limit switch. Not sure whether that is to stop itself from self destructing or else… so you likely still need to figure out how you will determine its stop points. If you are using run time, then it really needs to be on the device end as leaving that up to ST (non deterministic and with wide range of response time) might result in a door off its hinges ;-).


#6

How heavy are the doors, are they operated as vertical slides, horizontal slides, vertical lift, or horizontal swing?

And in particular, can you operate each door with one actuator or do you have to synchronize two?

I ask because there’s commonly a big difference between home theater cabinets and kitchen cabinets, with the home theater cabinets being much heavier and bigger and more likely to require two actuators.


(Mike Maxwell) #7

I used a thing shield with an arduino, to build this: https://youtu.be/5uyJuv1XU68


(Kyle Davis) #8

They’re very light. One actuator will be more than enough, thankfully. I need this to be a little easier on me as my first minor DIY.


(Mike Maxwell) #9

Check these guys out for actuators and how tos…


(Kyle Davis) #10

I’ve begun to try my best to understand your diagram by mocking up a circuit in Fritzing, but all that’s made me realize is that I definitely don’t completely understand what you mean. I’m sure I’m going to mess up terminology here, but aren’t the NO and NC pins on a relay related to the signal line coming from the (in this case) ZWave device, and are unrelated to the coil pins on the relay? Don’t the coil pins need to control the DC motor exclusively? I may have it all wrong, but I’m experimenting in Fritzing to try and understand how I’ve got it wrong.

Software comes so much easier to me, but I’m going to futz around with my circuit design until I either get it right or am completely lost.


(Alex) #11

The coil connections for the relays shown below are not shown in the diagram. The coils of the relays will be connected to the zwave device outputs. If the outputs provide +12V when on then the other side of each coil will be hardwired to negative… or the other way around if the output connect you to ground/negative when on (possible but less likely).

The connections shown below refer to the switching side of the (SPDT - single pull double throw) relay.

In basic terms, an SPDT relay has a common wire that is connected to one of two other wires. At rest (no power to relay coil) the common wire is normally connected to one of the two other wires generally refered to as NC - normally closed. The common wire is only connected to the other wire referred to as NO - normally open - when the coil is powered. The closed and open refer to a circuit where an open circuit is incomplete thus non operational while a closed circuit is complete thus operational.

In the diagram above, relay A (left) is powered given the COM is connected to NO, while relay B (right) is not powered given the COM is connected to NC.

Possibly helpful reading:


(Kyle Davis) #12

Got it. Or at least I realize one of my mistakes in understanding how it works. However, the Monoprice curtain controller that I plan to use has two separate signal lines with a timer I can set for each: one to open and one to close. So I’m unclear why I would connect any side of the DC motor to NC. Wouldn’t I want to connect each of those two signal lines to one of the two coil connections on each relay and connect each line of the DC motor to the NO on each relay? I have it somewhat mocked up in Fritzing now, so the diagram of what I thought I was supposed to do is pasted below.


(Alex) #13

In your diagram you show the negative lead from the power supply connected to both leads of the linear actuator. As soon as you actuate any of the two relays you will cause a short circuit. Say for example you remove the connection going to the linear actuator lead on the right… if you close the relay on the right the actuator will move in one direction, however if you close the relay on the left, you will cause a short circuit. In other words, if the direction of the actuator is controlled by reversing polarity, you cannot hardwire either of the leads from the power supply to the actuator. The actuator leads need to go to the commons on the relays and then NO and NC will have to be connected to + and - from the power supply. Doing this will allow you to control whether + or - is connected to any specific lead of the actuator. If - or + is connected to both leads then nothing moves, but if you have - to one and + to the other it will move in one direction and as soon as you invert this, it will move in the other direction.

This video might help however it takes this a bit further than what we are discussing. The video talks about limit switches (something you likely still have to consider) and shows the use of a DTDP switch. The switch he used in the video has 3 position… up, middle, down. The middles disconnects everything so the motor does not work, up and down causes the motor to move in one or the other direction. Although there are DTDP relays, you do NOT want to use one as it will result in your actuator never stopping… either going in one or the other direction. By using 2 SPDT relays you are achieving the same thing as the DPDT switch used in the video (both relays off will be equivalent to the middle position of the switch).


(Kyle Davis) #14

Oooohhhhhh. Ok. Yeah, I definitely see what you mean about shorting it out. I was thinking of it in my head as two completely different mutually exclusive circuits or something. Actually not sure what I was thinking. See what an electrical newbie I am at this? I modified my diagram. Does this look like what you mean? And thanks for all your assistance, btw.


(Kyle Davis) #15

Wait. I already realize that’s still not right. I think. I’m back to messing with it again.


(Kyle Davis) #16

Actually, I think that’s close. However, I’m realizing that I should probably connect the “STOP” pin 7 signal line as well or it can only go all the way one direction or the other. Is that correct? How would I go about wiring that in?


(Alex) #17

Getting closer :slight_smile: In your latest diagram you will end up with the actuator always moving in one direction unless you activate one of the relays. You need to have the same polarity on both relays so NC must have either + or - on both relays. This way, at rest (no power to either relay), the motor will be connected to both + or - and thus not move. Closing any one of the two relays will complete the circuit with both + and - being connected in one way or the other to the actuator.

I found a very basic user manual for the curtain module you picked and saw a Q&A that troubled me as it says “The Open, Close and Stop signals are about 1 second long.”. If this is the case then this setup will not work as you need something that keeps the relays actuated until the cabinet door has reached its correct position. In the first video I sent you, the presenter had 2 limit switches to stop the actuator at two specific positions. In another video I saw it looked like the actuator will stop once it has FULLY extended or retracted. Unless these built in limit stops are adjustable, you will not have much ability to calibrate the run… Some more complicated actuators provide analog (potentiometer) or digital (encoder) position feedback but then you need some electronics to handle that… An actuator with adjustable limit switches is likely your simplest and best choice. Once you find that you need to see what control it requires… a 1 second pulse will work with an actuator that has some electronics, not a bare motor.


(Kyle Davis) #18

Ok. That makes sense and answers my confusion over the “STOP” line, which I wouldn’t need in this case. Ok. I think I’ve got it right this time. :grinning:


(Alex) #19

Yes, your diagram now looks correct however please read my edited post above as this may not work with the control module you picked.


(Kyle Davis) #20

Regarding the 1-second comment, I saw that, but that’s just a user who didn’t know how to configure it properly. The manual at Monoprice indicates that it is configurable from 1-255 seconds.