fma38 wrote:

And no, I don't manage the backlash. Be aware that it is not that simple, and mainly depends on the load. For example, on the pitch axis, you don't know if the load will put the backlash on the up direction, or on the down direction, depending how the camera/lens is balanced... The wind can also be a nice trap for the yaw axis

Hey Frédéric!

Yes - that´s a vital point. I suggest to keep the counter-screws (?) tightened - and not to move the head by hand.
I check that frequently - and have no problems regarding precision  any more.

best to you, Klaus

klausesser wrote:

fma38 wrote:

And no, I don't manage the backlash. Be aware that it is not that simple, and mainly depends on the load. For example, on the pitch axis, you don't know if the load will put the backlash on the up direction, or on the down direction, depending how the camera/lens is balanced... The wind can also be a nice trap for the yaw axis

Hey Frédéric!

Yes - that´s a vital point. I suggest to keep the counter-screws (?) tightened - and not to move the head by hand.
I check that frequently - and have no problems regarding precision  any more.

best to you, Klaus

And here we are, in that case I'm sure the Merlin compensates the backlash internally, as I expect such a low cost gear has at least 1.5° backlash.
I don't have a Merlin, but maybe one can confirm how far can you turn the head manually, before the encoder starts to rotate. You have to do this test in both directions.

fma38 wrote:

Yes, but you can't do anything if there is some backlash in the gearbox; every direction change will loose a few degres before the gears are again in contact...

Sure you could, but seems you don't have to in this case.
The only thing you need to know is the backlash in ° and then you add additional steps to the first goto command when ever the direction of the head is changing. This practice is used even in CNC machines.

panoguy wrote:

And here we are, in that case I'm sure the Merlin compensates the backlash internally, as I expect such a low cost gear has at least 1.5° backlash.
I don't have a Merlin, but maybe one can confirm how far can you turn the head manually, before the encoder starts to rotate. You have to do this test in both directions.

The very moment you move one of the head´s axis the encoders rotate. There´s no visible dead-time: it´s fixed at the gear´s axis.
Generally the precision seems to be very sufficient - it´s covered by the overlap of 25/30% anyway.

I use a 300mm sometimes - very narrow steps in portrait-mode. No problems so far.

best, Klaus

there is an easy way to visualize Merlins backlash

just define some driving patterns different in motion per axis
- steady going
- zig zaging

mount a laser pointer on Merlin bracket and do a long time exposure with a fixed cam while running the pattern

Merlins backlash is partly compensated via the inertia of the slipping clutch

I used a tele-lens, and glued some millimetered-paper on the wall... Very accurate! Then, atan() is your friend...

panoguy wrote:

fma38 wrote:

Ok, here is a first version. Just put it in your plugins dir:
linux: ~/.config/papywizard2/plugins:
windows: C:\Documents and settings\<user>\Application Data\papywizard2\plugins\

Just got my first N800 and managed to install Papywizard.
The only thing I did not find in hurry, where do I have to copy the plugin on the N800 ?

I just read the documentation and I guess I found it /home/user/.config/papywizard2/plugins

I installed the latest dev. version - 2.1.15-1 - this morning and it seems to include a 'panoguy' plugin:
http://www.papywizard.org/wiki/Download … ntversions

Which version did you install?

fma38 wrote:

Panogy, this is the correct path. But try the 2.1.15 release. As Andrew said, the plugin in now included.

Wow, Thank you, Frederic you always exceed my expectations...

Yes sure, I did install the latest version now ;-)
But how do I replace the plugin if I need to change anything?
For some reason the connection is not working with the included plugin, it fails on axis 1.
I made a copy of the 'old' plugin and saved it under a new name. With that plugin the connection works fine, but I can't open the Shoot window.

Is there and difference in the new plugin?

Last edited by panoguy (2010-02-03 16:54:14)

fma38 wrote:

There should not be any difference. Can you send me your version?
Can you also send me the logs when it fails (for both cases)?

Ok thank you, have send you an PM, is there a way to attach a file? I pasted all into the message body ...

Good Morning,
If you don't mind, you can name it GigaPanBot

just to inform you:

Gigapanbot is already in use by Traugott Emrich for his pano robot

see:
gigapanbot.com gigapanbot.de

IMO you should not kidnap his name but find another pretty one

Last edited by Paul (2010-02-04 11:03:23)

Paul wrote:

Gigapanbot is already in use by Traugott Emrich for his pano robot

Maybe it IS Traugot!?

best, Klaus

Hi Frédéric
your last advise was very helpful:

The additional LF may cause some problems. Is it possible for you to only send CR?

I have changed the code to send a CR only at EOL instead of CR / LF (which is the default as long it is not suppressed).
Papywizard connects fine now and the communication handshake is much better.
The timeout and retry parameters also works fine and it looks much more promising now.
Will need to test some more details during the weekend ...

Gigapanbot plugin description

The plugin is a simplified version of the Merin/Orion protocol as described on the developer page: http://www.papywizard.org/wiki/DevelopGuide
It uses a simple asynchronous, ASCII serial protocol.

All commands are always initiated by the master (Papywizard).
The controller of the Gigapanbot waits for incoming commands from the master and sends back a response to the last received command.
The slave controller could be busy with other tasks and in some circumstances not able to respond immediately to a command from the master.
In case the master does not receive a valid response from the slave, the master will repeat the last command for a predefined number of retries. The timeout value and the number of retries can be set in Papywizard, Hardware/Plugins communication tab.

There are 3 important parameters which controls the position and the movement of the motors.
1. The value of the encoder position at initial startup is set to 8388608 (this value is send to the master as HEX value = 800000)
2. The encoder or stepper motor (steps) the head will count for one 360° turn.
3. As we can have different encoders or gear types, the second parameter could be different for the tilt axis and the pan axis.

All commands send by the master starts with ':', and ends with '\r' (in Windows this is a CR only, no Line Feed)
The head controller response always starts with '=', and ends with '\r'. (CR only)

This is the structure of the protocol:
1. the first character is the command
2. the second character is the axis number, it is mandatory, 1=yaw, 2=pitch axis
3. the next characters (up to 6) are used only for some commands and are send as HEX value, optional but mandatory for some commands

Valid commands are:
j<axis> read axis position, return is a 6 char HEX value   
f<axis> read axis status, return is 0=ready or 1=busy
L<axis> stop motors,
a<axis> get encoder count (steps) needed for a 360° turn, value is 6 char HEX value

G<axis><direction> Start moving to left or right, 0=increments (up/right), 1=decrements (down/left), this command is used to manually turn the head into a initial position.

I<axis><speed> Set motor speed, 3 possible dec values 0,2,4  (0=high speed, 2=medium speed, 4=slow speed)

S<axis><position> Drive to position, the position value is again a HEX value (ie. 8000A0) This command moves the head from his actual position (j encoder value) to the requested position.
For example if your head is at the initial zero position (HEX 800000) and receives a request to move to new position 8000A0, it will turn the stepper motor by exactly 160 steps to the right.

O<axis><state> Release camera, Shutter on axis=1, Autofocus on axis=2, ON state=1, Off state=0

e<axis> ask firmware version during first connect, max 6 char

F<axis><state> Connection status, state 0=not connected,  1=connected. The command is used to maintain the connection status at the slave controller.

Following (Merlin) commands are not used by now:
D not used
J not used

Last edited by panoguy (2010-02-15 21:59:12)