Wednesday, June 5, 2024

GPS-Enabled Automatic Access Point Placement

The Challenge of Indoor Navigation
Unlike outdoor environments, where GPS technology excels in providing precise location data, indoor spaces pose significant challenges. Traditional GPS signals struggle to penetrate buildings, leading to inaccuracies and poor performance. This has long been a hurdle for implementing efficient wireless networks in large, multi-level indoor spaces. The need for strategic placement of wireless access points (APs) to ensure optimal coverage and connectivity adds another layer of complexity. Achieving even 3 meters of location accuracy indoors has been accomplished with various methods of calibrating the wireless infrastructure or adding in Bluetooth beacons or Ultra Wide Band technology.

Once upon a time, you had to do pirouettes with your laptop in hopes of creating a calibration fingerprint for the wireless environment if you were attempting to get a semblance of location accuracy. See examples: LINK

Demand for indoor navigation has existed but has not always been feasible. Attempts at achieving indoor location awareness have been in place since the early 2000’s. From sprawling malls, hotels, to complex hospital layouts, the ability to accurately pinpoint locations and ensure robust wireless coverage indoors has been achieved in the past with a multitude of overlay networks. Things are finally changing. The latest innovation in this arena is GPS-enabled automatic access point placement, a cutting-edge development spearheaded by leading wireless hardware vendors. I heard about this in great detail at Mobility Field Day 11!
Recent advancements have enabled the integration of GPS technology with indoor positioning systems (IPS). Now GPS-enabled access points can auto place themselves on building floor plans. The management system still needs the scale set on the building floor plan and a few known locations to be defined for the GPS-enabled access points to auto-place their neighboring access points on the building floor plan. 

Currently, the Cisco automatic access point placement gives the end user the ability to rotate the access point layout to align with the boundaries of the building layouts within Cisco Catalyst Center. This video from Mobility Field Day 11 features Dave Benham from Cisco Systems explaining how this feature works
How It Works
1. GPS Integration: The access points have a GPS chip in it which helps each AP (access points) that can “hear” other access points figure out where they are in relation to each other.
2. Barometric Pressure Sensors: Some access point vendors can even place access points on the correct floor level of the building floor plan by utilizing the data detected by the barometric pressure sensor in the access point. Less barometric pressure is equated to being on a higher floor.
3. Accelerometer Sensor: This sensor can detect the angle at which the access point is physically installed. Ceilings inside buildings may not always be horizontal to the floor elevation, and this angle of installation (when known to the wireless infrastructure) will aide in accurate calculations in the wireless infrastructure system's location tracking algorithms.
4. Automatic Placement Algorithms: Leveraging AI (Artificial Intelligence) and machine learning, the system analyzes the digital map and the gathered location data to determine the most likely accurate placement of access points.
5. Deployment and Adjustment: Once the likely locations are identified, the access points are auto-placed on the digital floor plan within the wireless management system.
Leading wireless hardware vendors are integrating GPS-enabled automatic AP placement into their product offerings, providing businesses with advanced tools to enhance their wireless infrastructures’ location awareness.
The integration of GPS-enabled automatic access point placement on digital maps is a big deal for indoor navigation and context awareness. No more pirouettes!

As more wireless hardware vendors incorporate support for 802.11mc, further advancements in the accuracy of indoor location will become possible. 

802.11mc (Wi-Fi Round Trip Time) is an IEEE standard that enables devices to measure the distance to nearby Wi-Fi access points. This high-precision synchronization between peers and round-trip time calculation (Wi-Fi RTT (Round Trip Time)) for location estimation typically results in a reported location accuracy within one to two meters. Wi-Fi RTT has the potential to become a mainstream sub-meter-level indoor positioning technology as more vendors and client devices enable support for this functionality.

Splicing the Red Wire On Your Glowforge for less than $20

If your Glowforge laser suddenly stops emitting the laser but all the other functions seem to be normal (your laser powers on, the print head centers, focuses, moves back to home base, the print head goes through the motions of printing your project but no laser marks are being made), you may have a short in the high-voltage red wire that runs under the glass laser tube. Here is a link to a helpful video for locating the red wire in your Glowforge.

If you have a short in your red wire, it will look something like this:

The red wire runs under the glass laser tube, snug in an aluminum channel where the wire does not move, nor does it come into contact with anything else moving (that I can see). On the far right side of the laser tube (the side with the on/off button), the red wire is screwed to the metal laser tube "cap" with a 10m hex screw. Follow the disassembly instructions in the video above to remove the glass top side pieces from your Glowforge in order to access the attachment point of your red wire. Some Glowforge units ship with a black fiberglass protective sleeve over the red wire, but there have been reports of the red wire shorting out even through the protective sleeve.

Some users have reported success with using liquid electrical tape and a layer of heat shrink to repair the shorted wire. I used this repair method at first but only succeeded in 15 minutes of laser use before the wire shorted out through the repair in the same spot.

Steps to disassembly of the Glowforge to repair (splice) the red wire
  • Unplug your Glowforge Laser
  • Remove the three 10m hex screws from each of the glass top sides and remove the glass top sides
  • Remove the red silicone cap from the end of your laser tube
  • Remove the 10m hex screw from the red wire ring connector
  • Tie a sturdy piece of string/twine/curling ribbon to the ring connector on the end of your red wire.
  • Locate the red wire on the left side of your laser tube and slowly remove the red wire from the channel that runs under your glass laser tube
  • You may want to reroute your red wire under your glass laser tube someday. If you think you might want to do this, leave the twine in place and secure it so that you can pull another wire back through this channel without having to disassemble your whole laser.
  • Cut your red wire at the section where it shorted out. Remove small amounts of the wire until you reach a solid section of the wire and insulation.
  • Strip off 0.5 inches (half an inch) of insulation from your red wire.
  • Route your red wire through the aluminum hoop if possible (for cable management)
  • Slide one of the white plastic insulator pieces onto the left wire (tapered end of the white insulator to the left, threaded side to the right
  • Tin the end of the wire with a soldering gun and solder.
  • Loosen the screw on the small off-white connector piece
  • Insert the tinned wire into the small connector piece
  • Tighten the screw on the small off-white connector piece
  • Route the right hand side of your red wire as needed and affix the 10m hex screw to the end of the laser tube
  • Slide one of the white plastic insulator pieces onto the left wire (tapered end of the white insulator to the left, threaded side to the right
  • Tin the end of the wire with a soldering gun and solder.
  • Loosen the screw on the small off-white connector piece
  • Insert the tinned wire into the small connector piece
  • Tighten the screw on the small off-white connector piece
  • Thread the two larger insulated pieces together and tighten them by hand.
  • Ensure that the spliced wire is not making contact with the back of your laser unit by gently moving your laser tube assembly to the back of your unit with your hands.
There is a high-voltage splice kit available for purchase on Amazon (it is a two-pack of splice connectors even though you'll only need one splice connector assembly). If you want your kit fast, Amazon is the way to go—but you'll be paying $15 for the parts. If you have patience, you can order a similar kit from AliExpress for $2.

The center hole of the off-white hard plastic splice ends will need to be enlarged with a drill bit to accommodate the width of the Glowforge red wire. You will not need the black rubber end caps when you assemble your splice. The black rubber caps will not fit the Glowforge red wire and are extremely difficult to enlarge with a drill bit as they are made from rubber.

You can optionally apply two layers of heat shrink to the left side of your red wire where you have routed it through the aluminum "tray." When you reroute your red wire through the oval hole in the aluminum laser tube tray, you may desire a protective layer where the wire will rest against the somewhat sharp edge of the aluminum tray. We used two layers of heat shrink at this junction, just in case.

The aluminum "hoops" that run across the top of your glass laser tube DO NOT need to be removed for you to route your red wire through the rear side of the aluminum hoop. You'll use this hoop for your red wire cable management. Running your red wire through this area will ensure that your wire does not droop and possibly get in the way of your machine's running. The red wire will fit through the aluminum hoop in the space on the rear side of the glass laser tube.

If you have to repair your red wire again (if you get another short in the wire), you may find it better to replace the end of the red wire that screws to the right-hand side of your laser tube with a section of this wire. You'd have to recreate the ring connector end by stripping the insulation, tinning the wire, and crimping on a ring connector, and covering that in heat shrink tubing. Replacing the red wire would allow you to re-run your red wire back in the original channel under the glass laser tube and have the splice connectors tucked away, out of the way somewhere on the left side of your laser.

There will soon be a kit available with the replacement wire, splice kit, etc, and a how-to from a member of the Friendliest Glowforge Community on FB, but it is not available online at this moment.