How do I turn this knob?!?

[swharden]

Help guys! I need ideas! Here's the basic concept. I have a microscope whose stage is controlled by twisting two knobs.

The knobs that need twisting are on the bottom and left side of the image. There is little resistance when turning the knobs by hand. It's just... tedious. Supposedly this is a robotic stage controller, but the controller box is lost so they have to be turned by hand.

I would love to use picaxe to automate the twisting of these knobs, but before I get into the details of the code I'm trying to figure out how to connect a motor to these knobs with minimal interference to the microscope... (it's worth over $100,000 and I'm just a grad student).

Any ideas?? All I've come up with is some type of rubber-band tied around a DC motor and these knobs. Perhaps there's something more elegant??

 

[slimplynth]

Hello

Mike did some good stuff with stepper motors to control a stage micrometer

http://www.picaxeforum.co.uk/showthread.php?t=11345

and

http://www.picaxeforum.co.uk/showthread.php?t=11665

 

[eclectic]

@swharden

Can the black knobs be (temporarily) removed?
If so, then connect to Stepper motors, via couplings.

e

 

[cvrwy]

Do I see a cable coming out of the housing behind the knob on the bottom of the picture? If that is a cable, it leads me to believe that a stepper motor may be buried behind the knob. All you have to add is the electronics (picaxe et all)......
Also looks like a connector on the left....(9-pin D-sub???????)

 

[hippy]

Supposedly this is a robotic stage controller, but the controller box is lost so they have to be turned by hand.

Perhaps try and find another controller box or clone one. As noted, there seem to be connectors already fitted so it may be a much easier option than adding mechanics.

As it's worth $100K, I would have presumed there might be some support or help available from the manufacturer ?

 

[boriz]

I forget where, maybe instructables website, but I remember seeing a neat solution to a similar problem. Guy wanted to remote control his stereo amplifier volume control. He used a Picaxe > Servo system, with the native IR commands. The servo ‘horn’ (Actually a disk I think) had Velcro on it, and so did the front face of the volume knob. Apparently it worked ok, and was easily removable.
Your knobs will need to turn much more than the normal servo swing range. So you can either hack the servo for continuous rotation, or replace the servo feedback pot with a multiturn version (maybe with some gearing also).

 

[boriz]

Or maybe direct friction drive? Like a rubber drive wheel pressed up against the outer edge of the knob?

 

[Dave E]

I agree with cvrwy, looks like the stepper motors are already there. The knobs are just attached to the shaft. All you have to do is remove a cover to get to the connections.

Dave E

 

[Technical]

A quick google on 'prior' takes you to this page

http://www.prioruk.com/downloadcentre/dc_software.html

It looks like all you have to do is download the free software, find the protocol and then connect to the 9 way serial port (if it is serial).
Or if it just the stepper motors connected to the connector you can drive them direct.

Absolutely no hardware hacking required at all!

 

[Rickharris]

A quick google on 'prior' takes you to this page

http://www.prioruk.com/downloadcentre/dc_software.html

It looks like all you have to do is download the free software, find the protocol and then connect to the 9 way serial port (if it is serial).
Or if it just the stepper motors connected to the connector you can drive them direct.

Absolutely no hardware hacking required at all!

Impressive detective work Tec _ I had to look 2 or 3 times before I found the name

 

[manuka]

swharden: This PICAXE productivity should now knock months off your course, & serves perhaps to show the sort of mental horsepower these darlings creators are capable of. In return a few kind words would be in order to your probably disdainful (-" Anything under $100k can't be any good" ) post grad. superiors.