Using the UMass Xybernauts


Getting started in wearable computers is a very personal journey. Everyone has their own expectations for what the computer will provide, and their own constraints as to what they are willing to live with. This goes for both the software and hardware configurations. In some cases, getting into a system is just a matter of getting used to doing things in a different way, in other cases it is a matter of finding the right size and color for a font, the right way to mount the HUD, and the right way to wrap the cables around your body. You should take the time to experiment with many different configurations to see what fits you the best. Please make sure any changes to the hardware configuration are reversible, and please do not make any significant changes without asking first.


I strongly suggest that you learn to touch-type using the Twiddler keyboards. It will make your life a lot easier. The best way to learn is to spend 15 minutes every day with the keyboard in hand. It will take several weeks to get the raw motor skill down and to begin to learn the key mapping. Be patient. When your little finger cramps up, quit for the day.

Unallocated chords on the Twiddler can be programmed to produce any character or string that you want. You are welcome to add mappings, but please don't erase those that belong to others (we probably need some coordinated way of doing this).

For the faint of heart, we have a single wrist-mounted keyboard (which is impossible to touch-type on), as well as several small, standard-layout keyboards (which are not very portable). Simply detach the twiddler keyboard connector and replace it with the keyboard of your choice.

When you are developing code on the wearables, you will find it easiest to login to them remotely from a desktop machine (even while wearing the device).

Heads-Up Displays

The Xybernaut Heads-Up Displays are very versatile, but will take some getting used to.
  1. You need to decide whether you are left- or right-eye dominant (we will talk about a simple test for this in class). You want the mirror to be positioned over your dominant eye.

  2. Decide which mirror to use. For each HUD, a full and a half mirror is available. I have come to prefer the half mirror (but each has its strong points).

  3. Decide whether the mirror will be mounted on top of or below the LCD element. Again - each configuration has its own advantages.

  4. Position the mirror so you can see all of the screen. The LCD element has three adjustable axes with which you can play. In addition, there are three degrees-of-freedom in the mount point of the display (where it attaches to the head frame). This took a long time for me to get right. Have patience. Never position the mirror by grabbing the mirror itself, the arm that the mirror is mounted on, or the LCD element.

  5. Looking at the display will take some getting used to. The most common initial impression is that the image is out of focus. You simply have to train your eyes to focus at the right depth. In general, this problem goes away within a few minutes (although may repeat itself on the next few uses).

Booting the Xybernaut Wearables

Looking at connector side of the main unit (with the PCMCIA slot on top), the power button is located in the lower-right corner of the panel. Push briefly to turn the system on; you will see a brief flash of the power light, which will be followed by the Xybernaut logo on the display.

In general, you should only use this button to turn on the system. Pressing it when the system is already on potentially puts the machine in a bad state. There is one exception to this: if the machine is already on and in a funny state, the best thing to do is hold the button down for several seconds. This will turn the machine off and will be indicated by the power light going off. You can then reboot the machine by tapping the power button again (of course, the machine will have to perform disk repairs on reboot). Only use this technique if nothing else works. If you are able to login to the machine (either from the console or remotely), you are better off shutting down the system cleanly.

When you initially power up the computer and you are using the Twiddler keyboard, the bios will complain about not being able to see a keyboard (if you are using the HUD, look directly at the LCD element do not user the mirror - the image at this stage is not bright enough to see the reflection). I don't know whose fault this is, but the solution is to hit F1 on the twiddler (this is the NUM, ALT, and A keys all at once). This will bring up the linux lilo boot prompt. You then just need to wait for the login prompt.


For the instant, the APM driver is not working properly. Hence, the machines do not know when they are about to run out of power. As you should know, it is potentially damaging to simply cut power without properly shutting down the machine (primarily the problem is with the integrity of the disk). Please pay close attention to the power situation. If you experience problems with the machine losing power, please refrain from using it until you can contact Andy.

As a precaution on boot, the machines automatically schedule themselves to shut down after 3.5 hours. If you are not heavily loading the processor, then the machines will happily and cleanly shut themselves down. This also means that you should only boot a processor when it has a fresh battery (or is on shore power).

A heavily loaded processor drops the battery life to about 2 hours. If this is your situation, then you are responsible for monitoring the battery status yourself. You can do this by pulling the battery out of its pouch and punching the button on the front (all without disconnecting it from the power cable). The battery will light up a number of LEDs indicating the power remaining. If only one red LED comes on, please shut the machine down immediately.

To shutdown the machine, execute /sbin/shutdown -c to cancel the automatically-scheduled shutdown, and then a /sbin/shutdown -h now. Before doing this, make sure that no-one else is on the machine (via finger). Also - make sure you use the /sbin version of shutdown.

Once you run a battery down, please make sure that it gets on a charger. An alternative to running on batteries is to connect to shore power. The battery charger has a connector that can be used in place of the one for the battery (both connect to the main processor unit). To disengage, squeeze both sides of the connector and pull (gently). When you boot a machine on shore power, make sure that you cancel the automatically scheduled shutdown.

Equipment Access, Checkout and Allocation

By default, the machines will be housed in CS 144 (the robotics lab). In general, they will be left in a booted state, making it possible to login to these machines remotely. Because these machines utilize DHCP for IP address allocation, their apparent location on the net will change. You can find out what their current hostnames are from the machine tracker page.

The robotics lab will generally be occupied during the day (especially after 11 am). Please make yourself known to whomever is in the lab before you touch the wearable equipment. We will set up some specific times that the lab will be open. You are also welcome to find Andy or Jad in their offices for lab access. Note that there is a lot of other equipment in the lab space; please do not touch any of the robots or their components. If you need to borrow tools (for use in the lab) you are welcome to do so - but PLEASE ASK FIRST.

The wearables are available for checkout, as are the battery chargers, and extra keyboards (including the one wrist-mounted keyboard). You must sign out each piece of equipment before it leaves the room. For the time being, use of the equipment is restricted to the CS building, the 3rd floor of the LGRC, and the EdLab (in LGRT). You are personally responsible for any equipment that you check out. If a hardware problem develops while a machine is in your care, then YOU are responsible for making sure that it gets fixed. This does not necessarily mean that you have to personally solder things back together, but you need to take the steps to make sure that it is fixed by someone. Please do not do any hardware servicing without checking with Andy first.

Whenever you have the computers in public spaces (or private spaces with lots of foot traffic), please keep the computer attached to your body -- REALLY.

We will not have any formal means by which a machine is allocated to a particular group. As the homework assignments and projects begin, you should tend toward using one or two machines (hopefully with minimal overlap with other groups). This will make the process of keeping ones' files in sync much easier.

Each working group should only check out a single machine, unless the work explicitly calls for more than one. In the latter case, please give priority to groups without machines. Note that there are others not directly involved with the class who have work to do on these machines.

Three of our Xybernauts are equipped with Heads-Up Displays (sound works on two of these); two are equipped with wrist-mounted displays. Depending upon demand for the different configurations, it is conceivable that we can swap a wrist-mounted display for the HUD on neo to create a 3rd sound-capable HUDed machine. But - please ask first.


  1. Minimize the amount of wire that is hanging off of your body. Loops of wire have a tendency to catch on the world.

  2. If you are adding new wires to the wearable setup, make sure that all connections are strain-relieved properly. Soldered connections should not be subjected to constant bending or twisting.

  3. Don't drive while wearing a HUD.

  4. Make sure that the twiddler cable is not long enough that it can hit the ground if dropped while you are standing up.

  5. While conversing with someone (especially a person who is not used to the equipment), make sure that you move the HUD mirror so that you can make eye contact with both eyes.

Last modified: Tue Jan 30 18:55:44 2001