Also call ed haptics, I believe.
Anyone have any good app notes (URLs) on things like rotary controls where tuning nulls can be used to produce 'detents' in the knobs operation? I need some quick and dirty rules of thumb covering hardware, software and other consideration$ for some preliminary development and estimates
-- Paul Hovnanian mailto:Paul@Hovnanian.com ------------------------------------------------------------------ Sleep is for wimps. Happy, healthy, well-rested wimps, but wimps nonetheless.
You mean not fixed detents, but electrically controllable detents?
Interesting concept, if so. I haven't seen it in use anywhere!
One implementation I could think of is a stepper motor with phases energized to "hold". Combine with a shaft encoder and some smarts, of course, to turn off the hold except at the electronic detents.
Tim.
I've used stepper motors as shaft encoders. Power up one winding and look for pulses on the other one. Changing the current thru the powered winding could change the feel.
-- Luhan Monat: luhanis(at)yahoo(dot)com http://members.cox.net/berniekm "Any sufficiently advanced magick is indistinguishable from technology."
I think I remember a pro video machine, years ago that had a magnetic clutch on the jog/shuttle knob that changed the "feel" according to mode.
May be a (magnetised) ball that could be pushed into an idented disc
martin
Its called 'Haptics'. Google found me some good R&D stuff, but I'm looking for some quick and dirty rules of thumb to get an idea what sort of angular resolution, frequency response, etc.one needs to give a knob a good 'feel'.
Typical stepper motors (directly coupled to a knob) might not have sufficient angular resolution for good feel. I can feel them cogging, so unless some form of microstepping was used, they might be too rough.
Basically, I need some quick guidelines on which parameters are important and where corners can be cut to save a few $$.
-- Paul Hovnanian mailto:Paul@Hovnanian.com ------------------------------------------------------------------ Q: Why do mountain climbers rope themselves together? A: To prevent the sensible ones from going home.
Hello Paul,
Quite frankly, the marketing folks will be calling the shots, usually. This happened every time we finished a design. "This knob is too stiff, that one needs feedback" etc. I ended up marrying on of the marketeers that I met during such a session ;-)
I have seen some with 4096 (regular) steps but yes, they all cogged.
Talk to a marketeer. At the end of the day your solution is only as good as the customer says it is.
If it has to be rock bottom in cost I guess you'll need a plain old clutch and a DC driven solenoid, possibly spring-loading the whole thing. Solenoids are available cheaply for automotive use (may be too big though) but the clutch will most likely have to be a custom part. If space is an issue and you have to brake from the side that could be done via a bell crank.
For very long lifetimes look at spring loaded pool pump seals for clutch action. They have very long lasting friction surfaces but you have to make sure it is ok to operate under dry conditions with no stuff flaking off etc.
Regards, Joerg
I agree. It really depends on who this thing is built for. If you want to simulate the endoscopic instruments for heart surgery, you'll need an immense resulution. On the other end of the spectrum are thos Logitech mice that would 'click' or 'hop' when the user moved across a window border -
1-bit haptics ;-)The simple way is to start some motion (magnet, motor with weight, vibration) when something happens with the device. This is not really force feedback, but works in low dosage.
If you want real force feedback, you must measure the position of the manipulator and the force that is applied to it (many only measure the position!), and make some kind of actuator react as fast as possible. The human sense for touch is very hard to fool. So cutting corners is limited to what feels sufficient for you (or your client).
"Joerg" schrieb im Newsbeitrag news:ZI8ne.926$ snipped-for-privacy@newssvr13.news.prodigy.com...
ALPS - no doubt among a few others - have made DC motor controlled pots mainly for remote control audio applications. Less cogging than the stepper approach.
Wouldn't be too tricky to energise the motor so as provide resistance to movement ( feedback from the servo track ) when you found your null point.
Graham
Hello Paul,
It might pay to check out higher end joysticks. I guess high end in this category means over $20 or so.
I have never seen one myself but was told by a kid that there are tactile feedback joysticks. IOW the stick force changes according to some software parameter that the video game spits out. The same is true for aircraft controls but that would be very expensive stuff.
Regards, Joerg
What software? Join the knob to a DC motor, and energize the motor according to tuning.
The old FM discriminator curve:
/|
------/ | /------- |/
seems what should be the controlling element. And if there is not enough friction, it might become an autotune feature. Be sure to use a non-cogging motor.
Thomas
Golly, Ampex did electronically controlled detents on the VPR-3 1" video recorder back in '83. It is a shaft encoder with a magnetic clutch on the back. It feels remarkably 'mechanical'. Yes, I still work on these dinosaurs-- in fact, yesterday. Sony and Panasonic copied it in several models though I don't know if there are any consumer machines that use this (so you could play with it).
GG
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