How to Control a DC Linear Actuator using input from an optical incremental encoder with Arduino?

@tckellogg Good information. Start with the servo sketch or the motor sketch you found and simply replace the servo or motor with the actuator. You will probably need to 'map' the servo signal to appropriate linear actuator signals. Look Here the DC motor example is probably your best bet. Both examples you mention however are fundamentally different in that they are limitless. Your actuator has a minimum and maximum extension so your trim wheel/encoder when it gets to the 'end' of it's input can either just continue to spin with NO effect on the actuator (see the map statement above) or build in mechanical stops. 

I have no idea how the actuator is wired, and subsequently what pins you need on an arduino so it might be more complicated than I think but the concept is not too difficult, the map function is your friend.

Here you can see the control columns and rudder pedals from an actual 737 I am using to build my simulator. I am using a DC Linear Actuator and springs to simulate changes in control forces similar to what an actual plane experiences in changing flight configurations. When the aircraft needs to be trimmed to alleviate control forces on the flight controls the trim is activated either manually or electrically which turns the trim wheels, (not Pictured above) this turns a shaft which is attached to the incremental optical encoder. I wish to take the input from the encoder and use it to activate a DC linear actuator to extend, stop, or retract based upon clockwise, stationary, or counter clockwise movement of the encoder. The extension or retraction of the actuator increases or decreases forces acting on the flight controls.

@tckellogg YUP, been to flight school, I know what you mean.

@tckellogg Does this help, all that is needed is to read the encoder and map it's values to the digital writes to the actuators. Since encoders are freewheeling, you will need to use program logic to assign map value inputs. What I mean is count the encoder signals but only untik a max value then no more, this might be 1 to 1024 for example. 

https://www.firgelliauto.com/blogs/tutorials/how-do-you-control-a-linear-actuator-with-an-arduino

Here is another good example, just needs to be modified to use the encoder as input.

https://arduinogetstarted.com/tutorials/arduino-actuator

@zander 

Thanks Ron. No need to worry about limits as I already have addressed this. The shaft the encoder is attached to has fittings attached to it that have limit switches that activate to stop the motor activating the trim wheels in either directions. So once they reach their limit the encoder stops. If I understand this correctly. Here is a picture of a throttle mockup I am using to test before I hookup my actual throttle. Next to it you can see the shaft with the encoder attached and the limit switches.

@zander 

Thanks for the advice. Hopefully I can work on it after work.

@tckellogg Excellent. This makes it easier. simply install the encoder (pot), hook up an arduino and analogue read sketch and print out the values from one extreme to the other. Now look up map, now determine the max and min numbers for the actuator motor drivers. Fill in the map statements with the results of those two exercises.

@tckellogg When you say encoder, do you mean what I call a potentiometer or a disk with slots in it. Both can work, the pot is a trivial modification to any actuator sketch with an L298 motor controller like this one.

https://arduinogetstarted.com/tutorials/arduino-actuator

In the examples they run the actuator to the limits, just replace the HIGH and LOW with values from the encoder that have been 'mapped' to actuator values.

@zander No its not a pot, it's an optical incremental rotary encoder

@tckellogg Ok, different device but similar function. I see there are YT vids on reading it so again, determine max and min values and put them in the map function in the input side.