Servomotors split connection

Hitec robotics including ROBONOVA humanoid, HSR-8498HB servos, MR C-3024 Controllers and RoboBasic
11 postsPage 1 of 1
11 postsPage 1 of 1

Servomotors split connection

Post by Landy » Sun Dec 09, 2012 3:29 pm

Post by Landy
Sun Dec 09, 2012 3:29 pm

hello
I'm trying to connect two Hitec HSR5980SG in shared mode, through the Y connector.
The two servo motors must operate in opposition so I reprogrammed the firmware of the two servo (through the HMI servo programmer), so that one of the two turns normal and the other to reverse.
In this way, for example, when sending command MOVE G6A 150, both of the servos are positioned at the same angle.
The problem is that when I do a reset or turn on the MRC3024, for a moment, the two servo motors, literally splash in an area other than the standard (150).
This happens only when two servomotors are connected together.
If I do the same thing with a single servomotor, nothing happens and it is positioned evenly.

Is there a way to fix it?

sorry for my bad english
landyandy
hello
I'm trying to connect two Hitec HSR5980SG in shared mode, through the Y connector.
The two servo motors must operate in opposition so I reprogrammed the firmware of the two servo (through the HMI servo programmer), so that one of the two turns normal and the other to reverse.
In this way, for example, when sending command MOVE G6A 150, both of the servos are positioned at the same angle.
The problem is that when I do a reset or turn on the MRC3024, for a moment, the two servo motors, literally splash in an area other than the standard (150).
This happens only when two servomotors are connected together.
If I do the same thing with a single servomotor, nothing happens and it is positioned evenly.

Is there a way to fix it?

sorry for my bad english
landyandy
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Post by Landy » Sun Dec 09, 2012 4:07 pm

Post by Landy
Sun Dec 09, 2012 4:07 pm

IMAGE:


Image
IMAGE:


Image
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Post by Landy » Sat Dec 15, 2012 4:44 pm

Post by Landy
Sat Dec 15, 2012 4:44 pm

the datasheet for the servo Hitec HSR-5980SG exist?

my idea is to turn off the transistor of one of the two servo motors in order to prevent him from reading the HMI.
in this way the signals should not interfere with each other.

following the logic of the circuit diagram of 'HSR8498HB, I turn off the transistor q9, to prevent the response from the servo.

Image

any suggestions?

landyandy
the datasheet for the servo Hitec HSR-5980SG exist?

my idea is to turn off the transistor of one of the two servo motors in order to prevent him from reading the HMI.
in this way the signals should not interfere with each other.

following the logic of the circuit diagram of 'HSR8498HB, I turn off the transistor q9, to prevent the response from the servo.

Image

any suggestions?

landyandy
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Post by PaulL » Sun Dec 16, 2012 7:04 am

Post by PaulL
Sun Dec 16, 2012 7:04 am

The simple answer is to use separate channels off the MR-C3024 for each servo.

The mechanism in the picture isn't something I would recommend to do with servos. Aside from trims, servos themselves just aren't highly accurate - they'll fight each other, maybe only a little, maybe a lot, probably more at certain positions than others.

What happens if you connect both to the MR-C3024 after it has powered up? If this is OK, you might try inhibiting the PWM signal until after the board is powered up.
The simple answer is to use separate channels off the MR-C3024 for each servo.

The mechanism in the picture isn't something I would recommend to do with servos. Aside from trims, servos themselves just aren't highly accurate - they'll fight each other, maybe only a little, maybe a lot, probably more at certain positions than others.

What happens if you connect both to the MR-C3024 after it has powered up? If this is OK, you might try inhibiting the PWM signal until after the board is powered up.
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Post by i-Bot » Sun Dec 16, 2012 12:37 pm

Post by i-Bot
Sun Dec 16, 2012 12:37 pm

If you are prepared to modify the servo internals, you might also try connecting just the output h bridge of one servo to the processor of the other servo reversing the connections. This might stop them fighting over position, and not include variables from the potentiometers and any firmware setttings into play.
If you are prepared to modify the servo internals, you might also try connecting just the output h bridge of one servo to the processor of the other servo reversing the connections. This might stop them fighting over position, and not include variables from the potentiometers and any firmware setttings into play.
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Post by Landy » Sun Dec 16, 2012 4:22 pm

Post by Landy
Sun Dec 16, 2012 4:22 pm

in the meantime, thank you.

The simple answer is to use separate channels off the MR-C3024 for each servo.


you're absolutely right.
the problem is that I need to save pins on the MRC and also because in this way is much simpler command them.

they'll fight each other


in fact it was a little difficult to program them correctly.
the first servo-motor is set as a normal rotation while the other is in reverse.
the dead zone is set to the value 3 in the servo programmer and I reprogrammed the range of both (right, center, left), so as to be aligned as much as possible.
fiuuu!!

What happens if you connect both to the MR-C3024 after it has powered up?


a port for each servo?
In this case, if the command GETMOTORSET is set to 1, all goes well and the motor remains locked in position.
if I connect them together, after a reset or power up, they automatically place to move 100.

If you are prepared to modify the servo internals.................

Wow this is a super idea.

I think a little above and see how I can do.

however, today I did something crazy.
I tried to replace the original Atmel with that of a HSR8498HB.
currently seems to be going okay.

there are contraindications about?


always very kind
landyandy
in the meantime, thank you.

The simple answer is to use separate channels off the MR-C3024 for each servo.


you're absolutely right.
the problem is that I need to save pins on the MRC and also because in this way is much simpler command them.

they'll fight each other


in fact it was a little difficult to program them correctly.
the first servo-motor is set as a normal rotation while the other is in reverse.
the dead zone is set to the value 3 in the servo programmer and I reprogrammed the range of both (right, center, left), so as to be aligned as much as possible.
fiuuu!!

What happens if you connect both to the MR-C3024 after it has powered up?


a port for each servo?
In this case, if the command GETMOTORSET is set to 1, all goes well and the motor remains locked in position.
if I connect them together, after a reset or power up, they automatically place to move 100.

If you are prepared to modify the servo internals.................

Wow this is a super idea.

I think a little above and see how I can do.

however, today I did something crazy.
I tried to replace the original Atmel with that of a HSR8498HB.
currently seems to be going okay.

there are contraindications about?


always very kind
landyandy
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Post by Landy » Sun Dec 16, 2012 4:40 pm

Post by Landy
Sun Dec 16, 2012 4:40 pm

just to keep you informed, I made the change to the pin of the HMI.
I noticed that the wiring diagram of the two servo motors seems to be identical, (8498 and 5980), I simply disconnected the pin PD1 (TXT), but unfortunately not much has changed.
the problem remained.

stay tuned ....
landyandy
just to keep you informed, I made the change to the pin of the HMI.
I noticed that the wiring diagram of the two servo motors seems to be identical, (8498 and 5980), I simply disconnected the pin PD1 (TXT), but unfortunately not much has changed.
the problem remained.

stay tuned ....
landyandy
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Post by Landy » Sun Dec 16, 2012 5:22 pm

Post by Landy
Sun Dec 16, 2012 5:22 pm

ok, this is what I think I understood.

Looking at the data sheet in the post above.

I disconnect the control terminals of H-bridge PD6 and PD7 and reconnect them in parallel to the controller of the other servo-motor.
Because the two servo rotate in opposition, simply I reverse the connections.
The PD6 of the first servo-motor, to the PD7 of the second.
The PD7 of the first, to the PD6 of the second.

the signal wire of the second servo motor I disconnected completely.
Only +Vcc and ground from battery source.


is that correct?

greetings.
landyandy
ok, this is what I think I understood.

Looking at the data sheet in the post above.

I disconnect the control terminals of H-bridge PD6 and PD7 and reconnect them in parallel to the controller of the other servo-motor.
Because the two servo rotate in opposition, simply I reverse the connections.
The PD6 of the first servo-motor, to the PD7 of the second.
The PD7 of the first, to the PD6 of the second.

the signal wire of the second servo motor I disconnected completely.
Only +Vcc and ground from battery source.


is that correct?

greetings.
landyandy
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Post by i-Bot » Sun Dec 16, 2012 6:34 pm

Post by i-Bot
Sun Dec 16, 2012 6:34 pm

Yes, that's the idea.

Only the servo with the active signal wire will respond, and that will be the driver for both of the H bridges.

Obviously the outputs of the inactive ATMega must be disconnected from the slave H bridge.
Yes, that's the idea.

Only the servo with the active signal wire will respond, and that will be the driver for both of the H bridges.

Obviously the outputs of the inactive ATMega must be disconnected from the slave H bridge.
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Post by Landy » Sun Dec 16, 2012 7:31 pm

Post by Landy
Sun Dec 16, 2012 7:31 pm

First I must thank you for availability and idea.
Second, I finally finished the change and I can say that it works well.
I have not done many tests.

photos:

removal of the resistors of the transistors.Image

details of the two resistors.Image

repositioning of the resistors.Image

Addition of the connection wires.Image

connectorsImage

final connections to the board.Image


best regards
landyandy
First I must thank you for availability and idea.
Second, I finally finished the change and I can say that it works well.
I have not done many tests.

photos:

removal of the resistors of the transistors.Image

details of the two resistors.Image

repositioning of the resistors.Image

Addition of the connection wires.Image

connectorsImage

final connections to the board.Image


best regards
landyandy
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Post by PaulL » Mon Dec 17, 2012 9:39 am

Post by PaulL
Mon Dec 17, 2012 9:39 am

i-Bot wrote:If you are prepared to modify the servo internals, you might also try connecting just the output h bridge of one servo to the processor of the other servo reversing the connections. This might stop them fighting over position, and not include variables from the potentiometers and any firmware setttings into play.


Nice! Good call, more than one way to skin a cat. :)
i-Bot wrote:If you are prepared to modify the servo internals, you might also try connecting just the output h bridge of one servo to the processor of the other servo reversing the connections. This might stop them fighting over position, and not include variables from the potentiometers and any firmware setttings into play.


Nice! Good call, more than one way to skin a cat. :)
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