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(...) gradually depress the sensor. There is not a sharp cutoff like there is with a typical contact switch. I tried building a touch sensor multiplexor, but I was unable to reliably get even 3 to work because the minimum resistance is quite large (...) (25 years ago, 24-Aug-99, to lugnet.robotics)
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| | touch sensors aren't just switches (was Re: ideas for a RIS 2.0
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(...) Wow. That's pretty darn disappointing. I even bought extra touch sensors to use in multiplexed designs (but I haven't made the multiplexer yet). I guess I'll have to build some of my own touch sensors... I wonder why LEGO designed the touch (...) (25 years ago, 25-Aug-99, to lugnet.robotics)
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| | RE: touch sensors aren't just switches (was Re: ideas for a RIS 2.0
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(...) Many "buttons" in today's electronic devices are designed that way. Check your TV remote control, your key-chain remote control for your garage door opener or car alarm, the buttons on your phone etc. It eliminates the need for a physical (...) (25 years ago, 25-Aug-99, to lugnet.robotics)
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| | RE: touch sensors aren't just switches (was Re: ideas for a RIS 2.0
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(...) As you may guess, cost is the driving factor. In one project for a desk fan (it's the Brookstone Battery Operated Desk Fan in case you care) the rubber switch for three buttons and custom molding cost 8 cents! per switch in quantity 20,000. (...) (25 years ago, 25-Aug-99, to lugnet.robotics)
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| | Re: touch sensors aren't just switches (was Re: ideas for a RIS 2.0
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(...) I think it also removes the need to eliminate "keybounce", the annoying thing that happens with real switches due to dirt on the contact surfaces and tiny arcs (sparks) just before initial contact. Regardless, it seems to me that I'll do (...) (25 years ago, 25-Aug-99, to lugnet.robotics)
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| | RE: touch sensors aren't just switches (was Re: ideas for a RIS 2.0
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(...) The actual source of bounce is NOT the arc just before contact. It actually is the bouncing of the contact due to the action of the spring in the contact! Well, if you were switching a really high voltage through a small switch, you would get (...) (25 years ago, 25-Aug-99, to lugnet.robotics)
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| | Re: touch sensors aren't just switches (was Re: ideas for a RIS 2.0
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(...) You can still get keybounce on rubber buttons. Perhaps there is a special design that would eliminate keybounce entirely, but in my experience some degree of debouncing is still required. I believe the transition is a more gradual one since (...) (25 years ago, 25-Aug-99, to lugnet.robotics)
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| | Re: multiplexed touch sensors [was: Re ideas for a RIS 2.0]
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(...) Having revisited this entire sub-thread, it seems people started rambling on (constructively, I think) about switch times, debouncing, etc. Getting back to multiplexed touch sensors, I bet it's possible to get the Lego touch sensors to work (...) (25 years ago, 25-Aug-99, to lugnet.robotics)
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| | RE: multiplexed touch sensors [was: Re ideas for a RIS 2.0]
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(...) The problem with the LEGO touch sensors is that their resistance varies with the force on the plunger. To get the debouncing algorithm to work, you need to know how long the switch might be in the indeterminate state. (...) Typical switch (...) (25 years ago, 25-Aug-99, to lugnet.robotics)
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| | Re: touch sensors aren't just switches (was Re: ideas for a RIS 2.0
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(...) That obviously depends on what type of physical design is used for the switch. Some switches are not capable of bouncing the way you describe because there is no impact or acceleration during contact (example: slide switches that move leaf (...) (25 years ago, 25-Aug-99, to lugnet.robotics)
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| | Re: touch sensors aren't just switches (was Re: ideas for a RIS 2.0
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Any motion between two hard surfaces, including sliding metal on metal (often called contact wiping), creates intermittent contact that has to be "debounced". The only switches that don't bounce are mercury-wetted contacts, such as one used to find (...) (25 years ago, 25-Aug-99, to lugnet.robotics)
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| | Re: multiplexed touch sensors [was: Re ideas for a RIS 2.0]
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(...) It sounds like you're saying that the intermediate resistance values happen only for some period of time (short by human standards) while the touch sensor "switches" from "on" to "off" or vice versa. Other people writing in this thread have (...) (25 years ago, 25-Aug-99, to lugnet.robotics)
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| | Re: multiplexed touch sensors [was: Re ideas for a RIS 2.0]
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(...) I don't doubt that there are reasonable creations that e.g. press a touch sensor button halfway for extended periods of time, but I can't think of any off the top of my head. Can anybody help me out here? My point was that in what I would (...) (25 years ago, 26-Aug-99, to lugnet.robotics)
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| | Re: multiplexed touch sensors [was: Re ideas for a RIS 2.0] [DAT]
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(...) Okay, I felt like I had some time, so I looked into this a bit. I skipped the first part and jumped right into measuring a waveform. I measured a faster waveforms for now, but might give it another go with a longer waveforms and higher (...) (25 years ago, 26-Aug-99, to lugnet.robotics)
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| | Re: multiplexed touch sensors [was: Re ideas for a RIS 2.0]
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(...) (snip) (...) I managed to use this touch sensor "feature" as sort of a poor man's bend sensor to improve my wall-following robot. It's a torbot-type design with a left and right feeler-type bumpers in front. Using NQC (thanks, Dave) I set the (...) (25 years ago, 27-Aug-99, to lugnet.robotics)
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| | Re: multiplexed touch sensors [was: Re ideas for a RIS 2.0]
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Some corrections to my last post: (...) should be: turning LEFT when greater than 1000, the robot kept its left feeler against (...) should be: spent most of the time between 101 and 110. (Once TRACKING the wall, I never *saw* (...) should be: (...) (25 years ago, 27-Aug-99, to lugnet.robotics)
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| | Re: multiplexed touch sensors [was: Re ideas for a RIS 2.0]
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(...) I gather the lever arms of the feelers gave you enough control over the touch sensor to stay mostly in the 100 to 110 range? It would seem to be difficult to keep the touch sensor in that position for long periods of time, since the sensor is (...) (25 years ago, 28-Aug-99, to lugnet.robotics)
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