Servo actuation questions

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minionhunter
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Joined: Fri Nov 04, 2016 5:36 pm

Servo actuation questions

Post by minionhunter »

Is there any way to get "two stops" out of the same servo?

I currently assume that you fire your servo and it moves to one position and either it either returns to starting position on its own or you fire it again or in reverse and it goes back to starting position.

The end position can be adjusted using various linkages.

Is there a way to set up a servo to go to either one of two final positions depending on the trigger you fire? Or would you need two servos each one set to a different final position?

minionhunter
Posts: 158
Joined: Fri Nov 04, 2016 5:36 pm

Re: Servo actuation questions

Post by minionhunter »

minionhunter wrote:
Tue Feb 04, 2020 4:23 pm
Is there any way to get "two stops" out of the same servo?

I currently assume that you fire your servo and it moves to one position and either it either returns to starting position on its own or you fire it again or in reverse and it goes back to starting position.

The end position can be adjusted using various linkages.

Is there a way to set up a servo to go to either one of two final positions depending on the trigger you fire? Or would you need two servos each one set to a different final position?
I hope this makes sense. I'm asking because I had the idea for two positions in how far the panel flips up for a flipper. With varying bar linkages I can figure out how to get the panel to go to the positions I want, but it seems like it would be limited to one specific position. What I want is to have two positions like 90 degrees and 120 degrees that it immediately moves to with the position based just on which button I push on the transmitter. Can the servo be told to only move so far based on the signal, or is it strictly set physically on the servo itself?

Also, if this is a failure on my part to read on this topic, I apologize and would be grateful for any links to reading or suggestions on books to read.

As always, thank you very much for your help.

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Kyro
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Re: Servo actuation questions

Post by Kyro »

the i6 has a 3 position switch... you may be able to do something with that...
position 1, fully closed
position 2, half open
position 3, full open for example...

never tried this though so i would need to confirm...

what i can say that works is having throttle hold set to say 50% so flicking that switch would open it to 50%, flicking it back would close... then using throttle stick you would have full range of motion...
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MarkR
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Re: Servo actuation questions

Post by MarkR »

Servos move to the position they're commanded, from "full left" to "full right", or whatever those positions are called, depending on the pulse width, typically 1000us / 2000us respectively (with 1500us being centre) - and anywhere in between, they are fully analogue.

You can do whatever your tx is set up to do. As Kyro said, some TXs have three-position switches (my tx are also Turnigy, and also have three position switches). The three-position switches generally by default, set full left, centre, and full right, I suppose fixed-wing aircraft pilots use them for things such as flaps or landing gear.

It's also possible to trim those channels so they don't do the full range, or centre in a different position.

SIDE NOTE: My ESC module uses the channel-6 switch for runtime firmware configuration,
Robots: Betsie - RaspberryPi controlled flipper bot with gyro stablisation - too clever for her own good?
Stacie - tidy flipper; 4wd driven by hair bands

minionhunter
Posts: 158
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Re: Servo actuation questions

Post by minionhunter »

Neat! Thank you guys!!!

minionhunter
Posts: 158
Joined: Fri Nov 04, 2016 5:36 pm

Re: Servo actuation questions

Post by minionhunter »

MarkR wrote:
Tue Feb 04, 2020 5:51 pm
Servos move to the position they're commanded, from "full left" to "full right", or whatever those positions are called, depending on the pulse width, typically 1000us / 2000us respectively (with 1500us being centre) - and anywhere in between, they are fully analogue.

You can do whatever your tx is set up to do. As Kyro said, some TXs have three-position switches (my tx are also Turnigy, and also have three position switches). The three-position switches generally by default, set full left, centre, and full right, I suppose fixed-wing aircraft pilots use them for things such as flaps or landing gear.

It's also possible to trim those channels so they don't do the full range, or centre in a different position.

SIDE NOTE: My ESC module uses the channel-6 switch for runtime firmware configuration,
What esc module is that one you use?

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MarkR
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Re: Servo actuation questions

Post by MarkR »

I made it myself, some info is here

https://github.com/MarkR42/malenki-esc

It's a little unconventional for Antweight robots because it uses a different interface to the RX, ibus or sbus, which is more commonly used on drones.

Basically it is a three-channel brushed ESC with mixing and a few optional features. The latest firmware implements fully automatic axe-mode and is used on my robot "Penelope" :) - you can see that on the video in the melee.
Robots: Betsie - RaspberryPi controlled flipper bot with gyro stablisation - too clever for her own good?
Stacie - tidy flipper; 4wd driven by hair bands

minionhunter
Posts: 158
Joined: Fri Nov 04, 2016 5:36 pm

Re: Servo actuation questions

Post by minionhunter »

MarkR wrote:
Tue Feb 04, 2020 10:19 pm
I made it myself, some info is here

https://github.com/MarkR42/malenki-esc

It's a little unconventional for Antweight robots because it uses a different interface to the RX, ibus or sbus, which is more commonly used on drones.

Basically it is a three-channel brushed ESC with mixing and a few optional features. The latest firmware implements fully automatic axe-mode and is used on my robot "Penelope" :) - you can see that on the video in the melee.
Sweet!

Do you have motor brake on it?

What does Penelope look like? I want to see her in the fight.

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MarkR
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Re: Servo actuation questions

Post by MarkR »

Does it have motor braking? Yes, see https://github.com/MarkR42/malenki-esc/ ... ing.c#L180

Here is a picture which I took just before the fights, in case it got broken (it didn't, despite fighting "Why Wait?")

Image
Robots: Betsie - RaspberryPi controlled flipper bot with gyro stablisation - too clever for her own good?
Stacie - tidy flipper; 4wd driven by hair bands

minionhunter
Posts: 158
Joined: Fri Nov 04, 2016 5:36 pm

Re: Servo actuation questions

Post by minionhunter »

MarkR wrote:
Tue Feb 04, 2020 10:40 pm
Does it have motor braking? Yes, see https://github.com/MarkR42/malenki-esc/ ... ing.c#L180

Here is a picture which I took just before the fights, in case it got broken (it didn't, despite fighting "Why Wait?")

Image
Cool! Thanks!

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