Low-tech approach



  • My vision of the haptic compass would not provide constant reminder of north but rather it would provide a reminder when in motion and facing north. I imagined the device would be implanted in the leg. While walking the magnet would align north and when the user was also facing north the implant would provide a "tap" during footfalls. If the user spun 360 he or she would feel a "tap" when passing a northerly orientation. Rather than powering a vibrator or a zapper the implant would rely on the motion of entire compass. The implant would be filled with a liquid of low viscosity to allow quick movement but still dampened by a fluid denser than air. Not to mention the pitfalls of an air cavity under the skin. Eesh.

    My thoughts about a minimal electronic compass probably belong in a different southpaw thread. Back to business then. My current experiments are in testing a cone as a compass spinner which has its movement restricted by a rubber cap. The idea will be to have the whole device vibrate from metal-on-metal contact when facing north and gently shaking the unit. When facing any other direction the "tapping" will be severely dampened by the rubber restraining the cone.
  • Here is a picture without the rubber cap but the spinner is in action.
  • https://catalog.precisionmicrodrives.com/order-parts/product/304-103-4mm-vibration-motor-6mm-type

    I know this isn't really low tech but its low hanging haptic fruit. combine this with a resistor, a halls effect transistor, battery, diametrically magnetized disk, and bio proof casing and your in business 
  • @Osteth that makes about 4mA supply current for the hall sensor (permanent). And about 80mA for your vibration motor when active. This would drain even bigger coin cells (about 100mAh) in far less than a day. Also, you have to protect your transistor from reverse voltage spikes since the motor is an inductive load, so add a diode to your list.
  • very true, its not really optimal I would actually use a compass IC  microcontroller and NFC communication interface with a rechargeable battery (recharge via NFC)  if I were to build one for real but I was trying to stay at lease somewhat close to a low tech approach.  Honestly I think a High tech approach would be smaller, easier to build, and provide a lot of additional functionality.  my good idea fairy is kinda tapped out on a mechanical solution for this.
  • Is anyone still working on this?  I had an idea which may or may not be useful eventually.  I was reading through this (semi-old) thread and saw @McStuff post "I have tried to work with spherical magnets but they want to point DOWN
    of all things.  So weird.  If someone can explain that phenomenon I
    would be grateful."  Of course it could be a lot of things (the compass could be broken or pointing at your belt buckle) but it also might be acting as an inclination compass, which depends on the angle of the Earth's magnetic field relative to the force of gravity.  The closer you are to the equater the more 'even' it will be.  And this got me thinking.  Inclination compasses are theorized to be part of animal magnetoreception, which has to do with how homing pigeons and other birds are able to navigate and migrate.  As far as orientation (the point of this implant), a spherical compass can maybe help figure out location (and altitude?) in addition to the direction provided of a 'traditional' compass. 

    Obviously, it's been hard enough to get a traditional compass going, so this might be something to save for the next step.  It also might be hard to detect the inclination to any degree of accuracy that would be useful.  I guess it might make more sense to look to GPS implants rather than fooling around with this, but then we're getting back into the electronics solution McStuff was trying to avoid.  So my idea doesn't actually help in the specific design at all, but it might spur people much more capable than myself to keep trying or pursue other lines of thought, I hope! 
  • What are our options for a non implantable compass? The old bulky northpaw design is what - three or four years old? If we rebuild it with modern technology I bet we could come up with a design that could fit within a belt or something similar. 

    Having this implanted eventually would be really cool, but in the interim having perfect direction sense even if it meant wearing something is a win. 

    They are still selling NorthPaws on the website officially, but having spoken with people who used it I'm not super impressed. The size is huge, it needs to be frequently calibrated, it looks like a prison anklet. Totally fine as a proof of concept, but not something that's really that useable.  
  • edited April 2015
    I am still working on this project but I haven’t been giving it the attention it deserves. A 3D printer has accelerated the process but a lot of work remains.

    The only haptic compass I know of is the NorthPaw. It wouldn’t be too difficult to cobble one together with an Arduino and a vibrator, or eight. Haptic piezo pads would also be an option that hasn’t been done to my knowledge.

    I don’t think anyone has made a phone app which vibrates according to direction. That would be worth $0.99 to me. That could be a market to someone with mobile programming skills. I looked into it but I don’t have the skills to write that program. My thought is that a phone could be worn in a breast pocket facing north and it would vibrate with more intensity as the wearer faced a more southerly direction. Calibration should already be set by the phone itself and retained between resets. Later, a calibration could be added so the phone could be moved to a pocket or arm band, neither of which allow the phone to face directly ahead of the wearer as with a breast pocket.

    If anyone wants to start a mobile program like this I bet you could get some support in a new thread.
  • edited April 2023

    I cast Revive on this thread after eight years.

    I finally made a working haptic compass with no electronics. I used a laser cutter on 3mm thick plywood and assembled it with nylon hardware. Brass also worked.

    The device is huge, so it is a proof-of-concept, not an implant. I have a couple of stacks of square neodymium magnets pinned between wooden slats and spikes. The spikes point up and down, making that assembly a compass spinner. The pointy ends are low-friction and fit into 1/4" (6mm) bolts that I carved divots into. When the spinner points north, it rubs against a hanging brass washer, and you can feel the collision from the two metals impacting. The south-facing magnets are lower, so they miss the washer.

    I have a detailed write-up on my blog.

    GitHub files, if anyone wants to make one.

    Miniaturization is next, so any ideas or help is welcome.

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