proximity sensor controlling an actuator

Thread Starter

Aidan OToole

Joined May 4, 2021
5
I want to build a garage type housing (under kitchen units) for a robotic hoover.

I am looking at using a proximity senor to control a 4" stroke micro linear actuator 12v with a built in limit switch, to open a small door, max load 22lbs.

once to robot moves the door will open and wont close till the robot activates the senor when it returns to the base. I have attached some relays that may work with this set up.
This is the proximity senor I have
Twidec/M18 1-10mm Detecting Distance Measuring Capacitance Proximity Sensor Switch NPN NC(Normally Close) DC 6-36V 300mA 3-Wire LJC18A3-H-Z/AX



The 12v supply will taken off the hoovers changing base.

I am looking if someone can suggest wiring layout on how this might work.
 

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GetDeviceInfo

Joined Jun 7, 2009
1,879
does your robot communicate with Alexa? If not, how do you envision that interaction? The query is looking for distinctions between those two states. Your indicated sensor alone won’t know the difference.
 
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GetDeviceInfo

Joined Jun 7, 2009
1,879
Ok, so assuming your garage is large enough that the robot can move outside the field of detection, within the closed door garage, it should be simple. All you need now is to link the sensor and actuator pin outs.
 

Thread Starter

Aidan OToole

Joined May 4, 2021
5
Ok, so assuming your garage is large enough that the robot can move outside the field of detection, within the closed door garage, it should be simple. All you need now is to link the sensor and actuator pin outs.
Not sure if its as straight as that, linking the senor direct to the actuator will only open the actuator, to close the actuator the current will need to be reversed! this is where the relays may work, this is my main problem!
 

Yaakov

Joined Jan 27, 2019
3,523
Not sure if its as straight as that, linking the senor direct to the actuator will only open the actuator, to close the actuator the current will need to be reversed! this is where the relays may work, this is my main problem!
You could use the state of the door to decide motor direction. A limit switch to sense the door state connected to a simple DPDT relay to switch polarity.
 

Yaakov

Joined Jan 27, 2019
3,523
can you do a design for that?
I glossed over some details, you have to apply a bit of logic with a pair of time delay relay and a latching relay for your application.

Here is a picture of how a DPDT switch is wired to revers polarity at its output. A relay would have the same wiring, though the terminals might be differently arranged:

1620229023937.png

I found that illustration here: https://www.vegoilguy.co.uk/reverse_polarity_switching.php

In your application, When the door was closed, a limit switch would activate a latching relay like this one so that the polarity was in the open direction. This would be through a time delay relay like this one, providing a short pulse (e.g.: 1 second). Then when power was applied to operate the door, the effect would be to open it. When the door was fully open a limit switch would operate the latching relay again with another time delay relay so the next time the motor was operated it would close.

Obviously, control of the motor to stop at open and close is a separate thing, this just manages the direction. The result would be like the behavior of a garage door.

All the foregoing said, if I was doing this I would use a microcontroller which would simplify things and make adjustments and new behaviors much easier.
 

GetDeviceInfo

Joined Jun 7, 2009
1,879
Not sure if its as straight as that, linking the senor direct to the actuator will only open the actuator, to close the actuator the current will need to be reversed! this is where the relays may work, this is my main problem!
Misunderstanding. I was requesting a hyper link to the devices you were intending to use. For the sensor, I could only find sales, but need specs. Same for actuator. Can’t recommend a wiring diagram without knowing the specific devices utilized.

I’m suggesting it will be as easy as sensing the robot and closing the door, else the door is open. If that’s not what you want, say what you want.
 
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