AMC-AASD15A servo controller

Hey Thanos

I know that I can set the stroke length in your controller, but I would like to know if there is a parameter in the servo controller itself that allows me to set a max value as an additional layer of safety.
Also, I would like to use an end stop switch to stop the actuator in case of an over-extension. Do you know if there is a way to wire an end stop switch directly to the servo controller?

Your help is much appreciated!

Dirty

If you set the stroke correctly and the motor calibrates, its impossible for the motor to move beyond the stroke range no matter what the software commands are, the AMC simply won't provide pulses to move the motor further.

If you absolutely want to add limit switch to the top side of the actuator, you will have to splice the db25 cable and install a NC switch on the wire on the pin 6 (servo enable line). But you will have to move the motor back manually once the switch is open (or have a manual bypass switch). Be aware the AMC will have no control of the actuator at that point.

Great! Thank you very much! Perfect answer!

Reason I am asking is, I am cautiously considering to get a 6DOF certified by authorities for actual flight training and I have started to look into the different requirements. One of the points is operational safety.

- I know that my software will never command anything more than 100% stroke.
- On top, I know that your controller will never command anything more than 100% stroke.

...but that still leaves me with a scenario in which a single point of failure could lead to an over-extension: If the user plays around in your controllers menu and unintentionally sets the max stroke to 700mm, for example, on an actuator that can deliver only 400mm, then there will be nothing stopping the servo from destroying the actuator and all of the rig with it (in the inevitably ensuing collapse of the rig). That's why I was looking for an additional end stop switch or limit setting directly in the servocontroller.

Is there a way, to safeguard the AMC AASD-15A controller against modifications by the user? A jumper maybe?

Thanks for your help!!!

Dirty

I can add in the next firmware a lockout jumper on S2 to prevent altering parameters, but you can always just set the DIP switch1 to OFF position and it will disable the LCD user menu access.

I'd personally find the lockout jumper an interesting option to have, but at the same time I am well aware that this feature is pointless for the vast majority of users who buy an AMC AASD-15A controller solely for their own use.
It's really only relevant if you imagine you deliver a 6DOF product to a local flight school where your sim will be operated by someone who might be a professional flight instructor, but has absolutely no clue of anything that is going on "under the hood" of this thing.

The DIP switch is a method that would do the job just as well.

Thanks, Dirty

Even if the user sets wrong stroke or leadscrew values, the servo itself has the ability to detect malfunctions and disable itself... see this video where I intentionally use wrong parameters to make it fail. It won't exactly break the actuator mechanics...

Great, that's exactly the scenario I had in mind: User changes lead setting or stroke length.

So as long as the actuators mechanical construction can withstand the maximum torque from the servo it should survive the envelope excursion and trigger an overload alarm (AL-04) in the servo drive.

Guess I will have to beef up the upper bearing block of my design

Thanks for the great help!

Can you adjust the stroke length of each actuator individually, or is the stroke length setting constant across all outputs?

Also, is it possible to use the gear reduction function to enable compatibility with a 20mm lead ball screw?

Thanos, is there a way to implement like a safety offset for the bottom position of the actuator?
What i mean is let's say i have 500mm actuators. if i configure everything correct then it will have middle position o 250mm and work both ways. when it comes to max extension it's not an issue because those 500mm are actually less than what the hardware is (they can actually extend to 520mm) but there is no buffer at the bottom so when the actuator wants to lower to it's min position it will bump the bottom, right?
we could probably set it 500mm but start 10mm above "zero" so it won't hit bottom hard...
makes sense?

Currently, after calibration, the motor backtracks one rotation, so there is enough buffer distance from the hard stop calibration point.

You can adjust the actuators for different strokes, even different leadscrew types if you like.

I used the most common leadscrew settings 4mm, 5mm, 10mm and 25mm advance. I could add the 20mm setting in the next firmware release. No problem. I'll make a note of it. Maybe I'll try to change the calculation to be more efficient so you can select any in-between numbers...

Updating a few things in the LCD menu to improve the navigation for the users. See in the video what is new:

excellent!
one additional thought that i have - would it be worth adding possibility to define what "park" pose looks like? i understand that currently "park" is always "all actuators in their lowest position" but i would benefit from having the option to ie. move platform to it's "back" position so it is parked closer to the wall in the room...
what do you think about it?

Normally for rigs that have 4 vertical actuators and TL and Surge actuators, there is an option in the LCD menu, "Disable Park", which will park normally the 4 vertical actuators on their lowest position, but keep centered the TL and Surge actuators. I hope that helps.

Thanks
Thanos

i was actually thinking about 6DOF to be parked in a position that is as far back as possible (but really any position that can suit particular needs). normally it is on all 6 actuators minimums so in the center of the base if you will. i see value in ability to park it in either max left/right or front back positions to make more room in case you're not using the rig...

I see. It could be done but you would need servos with electronic brake for the actuators to be able to hold position once you power them off. Usually as soon you power off, the load on the platform can backdrive the actuators to retract all the way down from gravity...

another question, since there are some doubts how will my 6DOF behave (in build thread) i was thinking in starting by small steps.
my actuators have 500mm usable stroke. let's say that i would like to start with 100mm stroke but from the middle of initial 500mm stroke (250mm from the bottom of actuator) so that my actuator min position is 200mm from bottom and max position is 300mm from bottom.
how can i obtain that? should i set AMC as per actuators (length 500mm) and then limit stroke in FlyPT Mover? if so, how? setting 500mm in the definition of rig and then limit range in filters?

The best way is to set the actuators stroke as its normally is (500mm) in the AMC controller, so it can calibrate and allow full motion to the range of the actuator. Then in the FlyPT you can define the actuator travel and scale down the motion travel if you don't want it to travel full stroke. Actually on the 6DOF model the travel of each actuator is a combination of heave-pitch-roll-sway-surge-yaw, so it naturally limits the travel for each DOF to allow combined travel of the actuators to fulfill all DOF together when needed. And of course you can limit that total travel more around the center position of the actuator in the FlyPT software.

Thanks
Thanos

thanks Thanos. when playing with Mover i've seen lowering GAIN should be enough to limit the extent to which it moves. all other parameters should be ok even if left in a config that allows it to fully move.
waiting for servos and will start making some tests hopefully next week...

I need a explanation of the Spike filter. The videos are not helping me. I have found that the spike filter is causing the rotary actuators to jerk.. In Fs2020 this causes a thumping in the seat.
I believed I need the spike filter to prevent personal injury to myself (whiplash) when for example crashing the plane in DCS..