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A project log for Pathfinder - Haptic Navigation

Wearable Navigation Assistance for the Blind

neilNeil 06/04/2015 at 09:450 Comments

Hey everyone, it's been quite a while since the last update! Development was intermittent over much of the past 9 months, but all those steps have added up to a new milestone revision, which has finally pulled all the parts together.
Pictures coming soon, but here are the major changes:

  1. Added H-bridge drive scheme for the motor, allowing more precise control over haptic patterns (active braking, for example)
  2. Integrated LiPo charging to the board, then took it off temporarily as I work out the more critical hardware
  3. Significant improvements to EMC and general grounding/signal integrity, thanks to greater accumulated knowledge. Not entirely necessary, but good to have!
  4. Added a micro-USB port for serial debug and charging (actually, the UART lines run directly on the TX/RX lines of the USB; they lead to a downstream FTDI board. Basically, I just like the micro-USB connector interface).
  5. Shrinks all around. Total dimensions are significantly reduced, making it cheaper to manufacture and hopefully easier to integrate, eventually.
  6. Full code cleanup, hopefully more readable than before. This isn't on Github yet, my sources are all kind of scattered and I need to redo my whole VCS setup. Everything, from HW to SW, will be up soon.

And onto the major, short term to-do list:

  1. Still gotta get that accelerometer online and verified. I've played with the MPU-6050 before, and have the basic code + some preliminary functions ready to go in the source, but haven't deployed yet since every board has a little defect that prevents use of the accel. I just lost another board to an unrelated power issue, so the new fixed boards should come in sometime this week, at which point we'll re-examine the IMU state of affairs. Certainly, it is the most complicated SW block in the project yet.
  2. Rebuild the full MVP and re-test usability characteristics, from user experience to battery life.
  3. Consider rolling my own ultrasonic sensor to enable a better form factor.
  4. And finally, start considering "wearable" integration more seriously. We have at least progressed to a less obstructive wristband, but actual ship-ready products can't have PCBs or components exposed, so I need to look into an enclosure or some other creative deployment scheme. Still a ways off though.

I'll also fix the lack of pictures soon. This is just, as the title states, a check in to confirm that Pathfinder is moving forward, but we're slowing down a bit as we move out of the barebones prototype phase. Additionally, I'll have much more time over these next few summer months, so progress is coming soon!

Neil

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